CN117580385A

CN117580385A - Light emitting device, manufacturing method of light emitting device and display device

Info

Publication number: CN117580385A
Application number: CN202210934533.1A
Authority: CN
Inventors: 龚浩天; 庄锦勇
Original assignee: Guangdong Juhua Printing Display Technology Co Ltd
Current assignee: Guangdong Juhua Printing Display Technology Co Ltd
Priority date: 2022-08-04
Filing date: 2022-08-04
Publication date: 2024-02-20

Abstract

The application discloses a light emitting device, a preparation method of the light emitting device and a display device, wherein the light emitting device comprises an anode and a cathode which are oppositely arranged, and a light emitting layer arranged between the anode and the cathode, the light emitting device further comprises a first carrier transmission auxiliary layer arranged between the anode and the light emitting layer, the material of the first carrier transmission auxiliary layer comprises first quantum dots, the band gap energy of the first quantum dots is smaller than that of the material of the light emitting layer, and/or the light emitting device further comprises a second carrier transmission auxiliary layer arranged between the cathode and the light emitting layer, the material of the second carrier transmission auxiliary layer comprises second quantum dots, and the band gap energy of the second quantum dots is smaller than that of the material of the light emitting layer, so that the carrier injection difficulty is reduced, the carrier injection level of the light emitting device is improved, and the light emitting efficiency and the service life of the light emitting device are further improved.

Description

Light emitting device, manufacturing method of light emitting device and display device

Technical Field

The application relates to the technical field of photoelectricity, in particular to a light emitting device, a preparation method of the light emitting device and a display device.

Background

The Light Emitting device refers to a type of device made using a photoelectric effect of a semiconductor, and includes, but is not limited to, organic Light-Emitting Diode (OLED) and quantum dot Light-Emitting Diode (Quantum Dot Light Emitting Diodes, QLED). An OLED or QLED has a structure resembling a "sandwich", i.e. comprising an anode, a cathode, and a light-emitting layer, wherein the anode is arranged opposite the cathode, and the light-emitting layer is arranged between the anode and the cathode. The luminous principle of the photoelectric device is as follows: electrons are injected into the light-emitting area from the cathode of the device, holes are injected into the light-emitting area from the anode of the device, the electrons and the holes are combined in the light-emitting area to form excitons, and photons are released from the combined excitons in a radiation transition mode, so that light is emitted.

The technology of the light emitting device has been developed for many years, and the performance index has been greatly improved, and the application development potential is also great, but the carrier injection level of the light emitting device needs to be further improved, especially the QLED, and is one of key influencing factors of the light emitting efficiency and the service life of the light emitting device.

Therefore, how to increase the carrier injection level of the light emitting device has important significance to the application and development of the light emitting device.

Disclosure of Invention

The application provides a light emitting device, a preparation method of the light emitting device and a display device, so as to improve carrier injection level of the light emitting device.

The technical scheme of the application is as follows:

in a first aspect, the present application provides a light emitting device comprising:

an anode;

a cathode disposed opposite the anode; and

a light-emitting layer disposed between the anode and the cathode;

the light emitting device further includes:

the first carrier transmission auxiliary layer is arranged between the anode and the light-emitting layer, and the material of the first carrier transmission auxiliary layer comprises first quantum dots, and the band gap energy of the first quantum dots is smaller than that of the material of the light-emitting layer; and/or

The second carrier transmission auxiliary layer is arranged between the cathode and the light-emitting layer, and the material of the second carrier transmission auxiliary layer comprises second quantum dots, and the band gap energy of the second quantum dots is smaller than that of the material of the light-emitting layer.

Further, an absolute value of a difference between the band gap energy of the first quantum dot and the band gap energy of the material of the light emitting layer is not higher than 0.6eV;

and/or the absolute value of the difference between the band gap energy of the second quantum dot and the band gap energy of the material of the light emitting layer is not higher than 0.6eV.

Further, the light emitting device is in an operating state, the first carrier transport auxiliary layer does not emit light, and/or the second carrier transport auxiliary layer does not emit light.

Further, the first quantum dot is a quantum dot obtained after the first luminescent quantum dot is subjected to white light irradiation treatment;

and/or the second quantum dot is a quantum dot obtained after the second luminescent quantum dot is subjected to white light irradiation treatment.

Further, the thickness of the first carrier transport auxiliary layer is 3nm to 8nm, and/or the thickness of the second carrier transport auxiliary layer is 3nm to 8nm.

Further, the material of the light emitting layer is selected from an organic light emitting material or a third quantum dot;

the organic luminescent material is at least one selected from diaryl anthracene derivatives, stilbene aromatic derivatives, pyrene derivatives or fluorene derivatives, TBPe fluorescent material, TTPA fluorescent material, TBRb fluorescent material or DBP fluorescent material

The third quantum dot, the first quantum dot and/or the second quantum dot are selected from at least one of single component quantum dot, core-shell structure quantum dot, inorganic perovskite quantum dot or organic-inorganic hybrid perovskite quantum dot independently of each other;

The material of the single component quantum dot and the quantum dot with the core-shell structureThe material of the core and the material of the shell of the quantum dot with the core-shell structure are selected from at least one of II-VI compound, III-V compound, IV-VI compound or I-III-VI compound, wherein the II-VI compound is selected from at least one of CdS, cdSe, cdTe, znS, znSe, znTe, znO, hgS, hgSe, hgTe, cdSeS, cdSeTe, cdSTe, znSeS, znSeTe, znSTe, hgSeS, hgSeTe, hgSTe, cdZnS, cdZnSe, cdZnTe, cdHgS, cdHgSe, cdHgTe, hgZnS, hgZnSe, hgZnTe, cdZnSeS, cdZnSeTe, cdZnSTe, cdHgSeS, cdHgSeTe, cdHgSTe, hgZnSeS, hgZnSeTe or HgZnSTe, the III-V compound is selected from at least one 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 or InAlPSb, the IV-VI compound is selected from at least one of SnS, snSe, snTe, pbS, pbSe, pbTe, snSeS, snSeTe, snSTe, pbSeS, pbSeTe, pbSTe, snPbS, snPbSe, snPbTe, snPbSSe, snPbSeTe or SnPbSTe, and the I-III-VI compound is selected from CuInS ₂ 、CuInSe ₂ Or AgInS ₂ At least one of them.

Further, the material of the first carrier transmission auxiliary layer is a first quantum dot, and/or the material of the second carrier transmission auxiliary layer is a second quantum dot;

and the material of the light-emitting layer is a third quantum dot.

Further, the third quantum dot has a bandgap energy of 2.7eV to 2.9eV;

and, the band gap energy of the first quantum dot is 2.3eV to 2.5eV, and/or the band gap energy of the second quantum dot is 2.3eV to 2.5eV.

Further, for the light emitting device including the first carrier transport auxiliary layer and the second carrier transport auxiliary layer, an absolute value of a difference between the bandgap energy of the first quantum dot and the bandgap energy of the third quantum dot is smaller than an absolute value of a difference between the bandgap energy of the second quantum dot and the bandgap energy of the third quantum dot.

Further, the first carrier transport auxiliary layer is stacked with the light emitting layer, and the first carrier transport auxiliary layer is in contact with the light emitting layer;

and/or the second carrier transmission auxiliary layer is stacked with the light-emitting layer, and is in contact with the light-emitting layer.

Further, the light emitting device further includes: a hole function layer disposed between the anode and the light emitting layer;

when the light emitting device includes the first carrier transport auxiliary layer, the hole function layer is disposed between the anode and the first carrier transport auxiliary layer;

the hole functional layer includes a hole injection layer and/or a hole transport layer, and for the hole functional layer including the hole injection layer and the hole transport layer, the hole injection layer is closer to the anode than the hole transport layer, and the hole transport layer is closer to the light emitting layer than the hole injection layer.

Further, the hole transport layer is made of NiO _x 、WO _x 、MoO _x CuO, poly (9, 9-dioctylfluorene-CO-N- (4-butylphenyl) diphenylamine), 3-hexyl-substituted polythiophene, poly (9-vinylcarbazole), poly [ bis (4-phenyl) (4-butylphenyl) amine]At least one of poly (N, N '-bis (4-butylphenyl) -N, N' -diphenyl-1, 4-phenylenediamine-CO-9, 9-dioctylfluorene), 4',4 "-tris (carbazol-9-yl) triphenylamine, 4' -bis (9-carbazol) biphenyl, N '-diphenyl-N, N' -bis (3-methylphenyl) -1,1 '-biphenyl-4, 4' -diamine or N, N '-diphenyl-N, N' - (1-naphthyl) -1,1 '-biphenyl-4, 4' -diamine;

And/or the material of the hole injection layer is selected from poly (3, 4-ethylenedioxythiophene): poly (styrenesulfonic acid), copper phthalocyanine, 2,3,5, 6-tetrafluoro-7, 7', 8' -tetracyanodimethyl-p-benzoquinone, 2,3,6,7,10, 11-hexacyano-1, 4,5,8,9, 12-hexaazabenzophenanthrene, crO _x 、MoS _x 、MoSe _x 、WS _x 、WSe _x Or at least one of CuS.

Further, the light emitting device further includes: an electron functional layer disposed between the cathode and the light emitting layer;

when the light emitting device includes the second carrier transport auxiliary layer, the electron functional layer is disposed between the cathode and the second carrier transport auxiliary layer;

the electron functional layer includes an electron injection layer and/or an electron transport layer, and for the electron functional layer including the electron injection layer and the electron transport layer, the electron injection layer is closer to the cathode than the electron transport layer, and the electron transport layer is closer to the light emitting layer than the electron injection layer.

Further, the material of the electron transport layer comprises a metal oxide selected from ZnO and TiO ₂ 、SnO ₂ 、BaO、Ta ₂ O ₃ 、ZrO ₂ At least one of TiLiO, znGaO, znAlO, znMgO, znSnO, znLiO, inSnO, alZnO, znOCl, znOF or ZnMgLiO;

And/or the material of the electron injection layer includes at least one of an alkali metal halide, an alkali metal organic complex, or an organic phosphine compound.

In a second aspect, the present application provides a method for manufacturing a light emitting device, where the light emitting device is a front-mounted structure, and the method includes the following steps:

providing an anode;

forming a light emitting layer on one side of the anode; and

forming a cathode on a side of the light emitting layer away from the anode;

wherein, before the step of forming a light emitting layer on one side of the anode, the preparation method further comprises the steps of: providing a first quantum dot solution, applying the first quantum dot solution on one side of the anode, and then drying to obtain a first carrier transmission auxiliary layer, wherein the material of the first carrier transmission auxiliary layer comprises first quantum dots, and the light-emitting layer is formed on one side of the first carrier transmission auxiliary layer, which is far away from the anode, and the band gap energy of the first quantum dots is smaller than that of the material of the light-emitting layer;

and/or, before the step of forming a cathode on the side of the light-emitting layer away from the anode, the preparation method further comprises the steps of: providing a second quantum dot solution, applying the second quantum dot solution on one side of the light-emitting layer far away from the anode, and then drying to obtain a second carrier transmission auxiliary layer, wherein the material of the second carrier transmission auxiliary layer comprises second quantum dots, the cathode is formed on one side of the second carrier transmission auxiliary layer far away from the light-emitting layer, and the band gap energy of the second quantum dots is smaller than that of the material of the light-emitting layer.

In a third aspect, the present application provides a method for manufacturing a light emitting device, where the light emitting device has an inverted structure, and the method includes the following steps:

providing a cathode;

forming a light emitting layer on one side of the cathode; and

forming an anode on a side of the light emitting layer away from the cathode;

wherein, before the step of forming the light emitting layer on one side of the cathode, the preparation method further comprises the steps of: providing a second quantum dot solution, applying the second quantum dot solution on one side of the cathode, and then drying to obtain a second carrier transmission auxiliary layer, wherein the material of the second carrier transmission auxiliary layer comprises second quantum dots, and the light-emitting layer is formed on one side of the second carrier transmission auxiliary layer away from the cathode, and the band gap energy of the second quantum dots is smaller than that of the material of the light-emitting layer;

and/or, before the step of forming an anode on the side of the light-emitting layer away from the cathode, the preparation method further comprises the steps of: providing a first quantum dot solution, applying the first quantum dot solution on one side of the light-emitting layer far away from the cathode, and then drying to obtain a first carrier transmission auxiliary layer, wherein the material of the first carrier transmission auxiliary layer comprises first quantum dots, the anode is formed on one side of the first carrier transmission auxiliary layer far away from the light-emitting layer, and the band gap energy of the first quantum dots is smaller than that of the material of the light-emitting layer.

and/or the absolute value of the difference between the band gap energy of the second quantum dots and the band gap energy of the material of the light emitting layer is not higher than 0.6eV;

and/or the thickness of the first carrier transport auxiliary layer is 3nm to 8nm;

and/or the thickness of the second carrier transport auxiliary layer is 3nm to 8nm;

and/or the material of the light-emitting layer is a third quantum dot.

Further, the third quantum dot has an emission wavelength of 400nm to 480nm, and/or the third quantum dot has a band gap energy of 2.7eV to 2.9eV;

and/or the band gap energy of the first quantum dot is 2.3eV to 2.5eV;

and/or the band gap energy of the second quantum dot is 2.3eV to 2.5eV.

Further, the preparation method of the first quantum dot solution comprises the following steps: providing a first luminescent quantum dot solution, wherein a solute of the first luminescent quantum dot solution is a first luminescent quantum dot, and performing white light irradiation treatment on the first luminescent quantum dot solution to convert the first luminescent quantum dot into the first quantum dot, so as to obtain the first quantum dot solution;

And/or, the preparation method of the second quantum dot solution comprises the following steps: providing a second luminescent quantum dot solution, wherein the solute of the second luminescent quantum dot solution is a second luminescent quantum dot, and performing white light irradiation treatment on the second luminescent quantum dot solution to convert the second luminescent quantum dot into the second quantum dot, so as to obtain the second quantum dot solution.

Further, the light emitting wavelength of the first light emitting quantum dot is 500nm to 560nm;

and/or the second luminescent quantum dot has a luminescent wavelength of 500nm to 560nm.

Further, the white light irradiation treatment is performed under the conditions that the air humidity is 30% to 80% and the temperature is 5 ℃ to 40 ℃;

and/or the illumination intensity of the white light irradiation treatment is 100lx to 5000lx;

and/or the illumination time of the white light irradiation treatment is 1 to 10 hours;

and/or the illumination wavelength of the white light irradiation treatment is 400nm to 760nm.

In a fourth aspect, the present application provides a display apparatus comprising a light-emitting device according to any one of the first aspects, or a light-emitting device manufactured according to any one of the manufacturing methods according to the second aspects, or a light-emitting device manufactured according to any one of the manufacturing methods according to the third aspects.

The application provides a light emitting device, a preparation method of the light emitting device and a display device, and the preparation method has the following technical effects:

in the light-emitting device, the first carrier transmission auxiliary layer is arranged between the anode and the light-emitting layer, the material of the first carrier transmission auxiliary layer comprises the first quantum dots, the band gap energy of the first quantum dots is smaller than that of the material of the light-emitting layer, so that compared with a hole injection barrier between the anode and the light-emitting layer, the hole injection barrier between the anode and the first carrier transmission auxiliary layer is lower, holes are easier to inject, the level of injecting holes from the anode to the light-emitting layer is improved, and the hole injection level of the light-emitting device is effectively improved; and/or, a second carrier transmission auxiliary layer is arranged between the cathode and the light-emitting layer, the material of the second carrier transmission auxiliary layer comprises second quantum dots, the band gap energy of the second quantum dots is smaller than that of the material of the light-emitting layer, so that compared with an electron injection barrier between the cathode and the light-emitting layer, the electron injection barrier between the cathode and the second carrier transmission auxiliary layer is lower, electrons are easier to inject, the level of electrons injected from the cathode to the light-emitting layer is improved, the electron injection level of the light-emitting device is effectively improved, and the light-emitting efficiency and the service life of the light-emitting device are improved.

In the preparation method of the light-emitting device, the first carrier transmission auxiliary layer and/or the second carrier transmission auxiliary layer by adopting the solution method has the advantages of simple preparation procedure, controllable operation process conditions and capability of meeting the requirement of large-scale industrial production.

The light-emitting device or the light-emitting device manufactured by the manufacturing method is applied to the display device, and is beneficial to improving the display effect of the display device and prolonging the service life of the display device.

Drawings

Technical solutions and other advantageous effects of the present application will be made apparent from the following detailed description of specific embodiments of the present application with reference to the accompanying drawings.

Fig. 1 is a schematic structural view of a first light emitting device provided in an embodiment of the present application.

Fig. 2 is a schematic structural view of a second light emitting device provided in an embodiment of the present application.

Fig. 3 is a schematic structural view of a third light emitting device provided in an embodiment of the present application.

Fig. 4 is an electroluminescence spectrum of the light emitting devices of example 7, comparative examples 2 to 4 in experimental examples of the present application.

Reference numerals illustrate:

1: a light emitting device; 11: an anode; 12: a cathode; 13: a light emitting layer; 15: a hole functional layer; 16: an electronic functional layer; 141: a first carrier transport auxiliary layer; 142: a second carrier transport auxiliary layer; 151: a hole injection layer; 152: and a hole transport layer.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. It will be apparent that the described embodiments are only some, but not all, of the embodiments of the present application. All other embodiments, which can be made by those skilled in the art based on the embodiments herein without making any inventive effort, are intended to be within the scope of the present application.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In addition, any methods and materials similar or equivalent to those described herein can be used in the present invention. The preferred methods and materials described herein are illustrative only and should not be construed as limiting the scope of the present application.

The following description of the embodiments is not intended to limit the preferred embodiments. In addition, in the description of the present application, the term "comprising" means "including but not limited to". Various embodiments of the present application may exist in a range of forms; it should be understood that the description in a range format is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the invention; it is therefore to be understood that the range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that a description of a range from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the ranges, such as 1, 2, 3, 4, 5, and 6, wherever applicable. In addition, whenever a numerical range is referred to herein, it is meant to include any reference number (fractional or integer) within the indicated range.

In this application, "and/or" is used to describe a correlation between associated objects, meaning that there may be three relationships, e.g., a and/or B, which may be expressed as: a alone, a and B together, and B alone. Wherein A (B) may be singular or plural.

The embodiment provides a light emitting device, as shown in fig. 1 to 3, the light emitting device 1 includes an anode 11, a cathode 12, and a light emitting layer 13, wherein the anode 11 is disposed opposite to the cathode 12, and the light emitting layer 13 is disposed between the anode 11 and the cathode 12. The light emitting device 1 further includes a first carrier transport auxiliary layer 141, the first carrier transport auxiliary layer 141 being disposed between the anode 11 and the light emitting layer 13, a material of the first carrier transport auxiliary layer 141 including first quantum dots having a band gap energy smaller than a HOMO level of a material of the light emitting layer 13; and/or, the light emitting device 1 further includes a second carrier transport auxiliary layer 142, the second carrier transport auxiliary layer 142 is disposed between the cathode 12 and the light emitting layer 13, and a material of the second carrier transport auxiliary layer 142 includes second quantum dots, and a band gap energy of the second quantum dots is smaller than a HOMO energy level of a material of the light emitting layer 13.

As used herein, "band gap energy," also known as energy bandwidth, energy gap, etc., is used to characterize the ease with which a molecule is excited, the higher the band gap energy, the greater the difficulty with which the corresponding molecule is excited, in an inorganic semiconductor, the band gap energy refers to the energy difference between the valence and conduction bands; in an organic semiconductor, band gap energy refers to the energy difference between the HOMO energy level and the LUMO energy level.

In the light emitting device 1 of the embodiment of the present application, the materials of the anode 11 and the cathode 12 are selected from at least one of metal, carbon material, or metal oxide independently of each other, and the metal is selected from at least one of Al, ag, cu, mo, au, ba, ca or Mg; the carbon material is at least one of graphite, carbon nano tube, graphene or carbon fiber; the metal oxide may be a doped or undoped metal oxide, for example, at least one selected from Indium Tin Oxide (ITO), fluorine doped tin oxide (FTO), tin antimony oxide (ATO), aluminum doped zinc oxide (AZO), gallium doped zinc oxide (GZO), indium doped zinc oxide (IZO) or magnesium doped zinc oxide (MZO). Anode 11 or cathode 12 may also be selected from a composite electrode of doped or undoped transparent metal oxide sandwiching a metal, the composite electrode including but not limited to AZO/Ag/AZO, AZO/Al/AZO, ITO/Ag/ITO, ITO/Al/ITO, znO/Ag/ZnO, znO/Al/ZnO, tiO ₂ /Ag/TiO ₂ 、TiO ₂ /Al/TiO ₂ 、ZnS/Ag/ZnS、ZnS/Al/ZnS、TiO ₂ /Ag/TiO ₂ Or TiO ₂ /Al/TiO ₂ At least one of them. The thickness of the anode 11 may be, for example, 40nm to 200nm, and the thickness of the cathode 12 may be, for example, 20nm to 200nm.

The thickness of the light emitting layer 13 may be, for example, 10nm to 50nm. The material of the light emitting layer 13 is selected from an organic light emitting material or a third quantum dot.

Wherein the organic light emitting material includes, but is not limited to, at least one of a biaryl anthracene derivative, a stilbene aromatic derivative, a pyrene derivative or a fluorene derivative, a TBPe fluorescent material, a TTPA fluorescent material, a TBRb fluorescent material, or a DBP fluorescent material.

The third quantum dot includes, but is not limited to, at least one of a single component quantum dot, a core-shell structure quantum dot, an inorganic perovskite quantum dot, or an organic-inorganic hybrid perovskite quantum dot.

For single component quantum dots and core-shell structured quantum dots, the material of the single component quantum dot, the material of the core-shell structured quantum dot, or the material of the shell of the core-shell structured quantum dot includes, but is not limited to, at least one of a group II-VI compound selected from CdS, cdSe, cdTe, znS, znSe, znTe, znO, hgS, hgSe, hgTe, cdSeS, cdSeTe, cdSTe, znSeS, znSeTe, znSTe, hgSeS, hgSeTe, hgSTe, cdZnS, cdZnSe, cdZnTe, cdHgS, cdHgSe, cdHgTe, hgZnS, hgZnSe, hgZnTe, cdZnSeS, cdZnSeTe, cdZnSTe, cdHgSeS, cdHgSeTe, cdHgSTe, hgZnSeS, hgZnSeTe or HgZnSTe, a group IV-VI compound selected from GaN, gaP, gaAs, gaSb, alN, alP, alAs, alSb, inN, inP, inAs, inSb, gaNP, gaNAs, gaNSb, gaPAs, gaPSb, alNP, alNAs, alNSb, alPAs, alPSb, inNP, inNAs, inNSb, inPAs, inPSb, gaAlNP, gaAlNAs, gaAlNSb, gaAlPAs, gaAlPSb, gaInNP, gaInNAs, gaInNSb, gaInPAs, gaInPSb, inAlNP, inAlNAs, inAlNSb, inAlPAs or InAlPSb, a group III-VI compound selected from SnS, snSe, snTe, pbS, pbSe, pbTe, snSeS, snSeTe, snSTe, pbSeS, pbSeTe, pbSTe, snPbS, snPbSe, snPbTe, snPbSSe, snPbSeTe or SnPbSTe, or a group I-III-VI compound selected from CuInS ₂ 、CuInSe ₂ Or AgInS ₂ At least one of them.

For the inorganic perovskite quantum dots, the structural general formula of the inorganic perovskite quantum dots is AMX ₃ Wherein A is Cs ⁺ Ion, M is a divalent metal cation, M includes but is not limited to Pb ²⁺ 、Sn ²⁺ 、Cu ²⁺ 、Ni ²⁺ 、Cd ²⁺ 、Cr ²⁺ 、Mn ²⁺ 、Co ²⁺ 、Fe ²⁺ 、Ge ²⁺ 、Yb ²⁺ Or Eu ²⁺ X is a halogen anion including but not limited to Cl ^- 、Br ^- Or I ^- 。

For the organic-inorganic hybrid perovskite quantum dots, the structural general formula of the organic-inorganic hybrid perovskite quantum dots is BMX ₃ Wherein B is an organic amine cation including, but not limited to, CH ₃ (CH ₂ ) _n -2NH ³⁺ (n.gtoreq.2) or NH ₃ (CH ₂ ) _n NH ₃ ²⁺ (n.gtoreq.2), M is a divalent metal cation, M includes but is not limited to Pb ²⁺ 、Sn ²⁺ 、Cu ²⁺ 、Ni ²⁺ 、Cd ²⁺ 、Cr ²⁺ 、Mn ²⁺ 、Co ²⁺ 、Fe ²⁺ 、Ge ²⁺ 、Yb ²⁺ Or Eu ²⁺ X is a halogen anion including but not limited to Cl ^- 、Br ^- Or I ^- 。

It is understood that the surface of the third quantum dot may further have a ligand attached thereto, the ligand including, but not limited to, at least one of an amine ligand, such as at least one selected from the group consisting of oleylamine, n-butylamine, n-octylamine, octaamine, 1, 2-ethylenediamine, and octadecylamine, a carboxylic acid ligand, such as at least one selected from the group consisting of oleic acid, acetic acid, butyric acid, valeric acid, caproic acid, arachic acid, decanoic acid, undecylic acid, tetradecylic acid, and stearic acid, a thiol ligand, such as at least one selected from the group consisting of ethanethiol, propanethiol, mercaptoethanol, benzenethiol, octathiol, octaalkanethiol, dodecyl thiol, and octadecylthiol, and a (oxy) phosphine ligand selected from at least one of trioctylphosphine or trioctylphosphine oxide.

Specifically, the light emitting device 1 shown in fig. 1 includes the first carrier transport auxiliary layer 141 but does not include the second carrier transport auxiliary layer 142; the light emitting device 1 shown in fig. 2 includes the second carrier transport auxiliary layer 142 but does not include the first carrier transport auxiliary layer 141; the light emitting device 1 shown in fig. 3 includes a first carrier transport auxiliary layer 141 and a second carrier transport auxiliary layer 142.

In the light emitting device 1 shown in fig. 1 and 3, the structural composition of the first quantum dot refers to the description of the third quantum dot, since the band gap energy of the first quantum dot is smaller than that of the material of the light emitting layer 13, the hole injection barrier between the anode 11 and the first carrier transport auxiliary layer 141 is lower than the hole injection barrier between the anode 11 and the light emitting layer 13, so that holes are easier to inject, thereby improving the level of holes injected from the anode 11 to the light emitting layer 13, effectively improving the hole injection level of the light emitting device.

To further increase the hole injection level, in some embodiments of the present application, the absolute value of the difference between the bandgap energy of the first quantum dot and the bandgap energy of the light emitting layer 13 is not higher than 0.6eV, so that the hole injection barrier between the first carrier transport auxiliary layer 141 and the light emitting layer 13 is lower than the hole injection barrier between the first carrier transport auxiliary layer 141 and the anode 11, thereby forming a gradient hole injection barrier, further increasing the hole injection level.

In order to further increase the hole injection level, in some embodiments of the present application, the first quantum dot is a quantum dot obtained after the first luminescent quantum dot is subjected to white light irradiation treatment. It should be noted that, the applicant found that the electroluminescent performance of the first luminescent quantum dot is reduced or not after the white light irradiation treatment, the reason may be that: the first luminescent quantum dot can be subjected to white light irradiation to cause ligand (such as-NH) connected to the surface of the first luminescent quantum dot ₂ or-COOH) undergo a phenomenon of exfoliation and/or of radical modification.

In order to both enhance the compactness of the first carrier transport auxiliary layer 141 and facilitate injection of holes from the first carrier transport auxiliary layer 141 to the light emitting layer 13, the thickness of the first carrier transport auxiliary layer 141 is 3nm to 8nm in some embodiments of the present application. The thickness of the first carrier transport auxiliary layer 141 may be, for example, 3nm to 4nm, 4nm to 5nm, 5nm to 6nm, 6nm to 7nm, or 7nm to 8nm, and the thickness of the first carrier transport auxiliary layer 141 is exemplified by 3nm, 4nm, 5nm, 6nm, 7nm, or 8nm.

In some embodiments of the present application, the material of the first carrier transport auxiliary layer 141 is a first quantum dot, and the material of the light emitting layer 13 is a third quantum dot.

Further, the band gap energy of the third quantum dot is 2.7eV to 2.9eV, and the band gap energy of the first quantum dot is 2.3eV to 2.5eV.

In order to further increase the hole injection level, in some embodiments of the present application, the first carrier transport auxiliary layer 141 is stacked with the light emitting layer 13, and the first carrier transport auxiliary layer 141 is in contact with the light emitting layer 13. The first carrier transport auxiliary layer 141 and the light-emitting layer 13 are in direct contact such that the first carrier transport auxiliary layer 141 and the light-emitting layer 13 are stacked, and no other functional layer is provided between the first carrier transport auxiliary layer 141 and the light-emitting layer 13.

In the light emitting device 1 shown in fig. 2 and 3, the structural composition of the second quantum dot refers to the description of the third quantum dot, since the band gap energy of the second quantum dot is smaller than that of the material of the light emitting layer 13, the electron injection barrier between the cathode 12 and the second carrier transport auxiliary layer 142 is lower than that between the cathode 12 and the light emitting layer 13, so that electrons are easier to inject, thereby improving the level of electrons injected from the cathode 12 to the light emitting layer 13, effectively improving the electron injection level of the light emitting device.

To further increase the electron injection level, in some embodiments of the present application, the absolute value of the difference between the bandgap energy of the second quantum dot and the bandgap energy of the light emitting layer 13 is not higher than 0.6eV, so that the electron injection barrier between the second carrier transport auxiliary layer 142 and the light emitting layer 13 is lower than the electron injection barrier between the second carrier transport auxiliary layer 142 and the cathode 12, thereby forming a gradient electron injection barrier, further increasing the electron injection level.

In order to further increase the electron injection level, in some embodiments of the present application, the first quantum dot is a quantum dot obtained after the second luminescent quantum dot is subjected to white light irradiation treatment. The second luminescent quantum dot has reduced or no electroluminescent property after being irradiated by white light.

In order to both enhance the compactness of the second carrier transport auxiliary layer 142 and facilitate injection of electrons from the second carrier transport auxiliary layer 142 to the light emitting layer 13, the thickness of the second carrier transport auxiliary layer 142 is 3nm to 8nm in some embodiments of the present application. The thickness of the second carrier transport auxiliary layer 142 may be, for example, 3nm to 4nm, 4nm to 5nm, 5nm to 6nm, 6nm to 7nm, or 7nm to 8nm, and the thickness of the second carrier transport auxiliary layer 142 is exemplified by 3nm, 4nm, 5nm, 6nm, 7nm, or 8nm.

In some embodiments of the present application, the material of the second carrier transport auxiliary layer 142 is a second quantum dot, and the material of the light emitting layer 13 is a third quantum dot.

Further, the band gap energy of the third quantum dot is 2.7eV to 2.9eV, and the band gap energy of the second quantum dot is 2.3eV to 2.5eV.

To further increase the electron injection level, in some embodiments of the present application, the second carrier transport auxiliary layer 142 is stacked with the light emitting layer 13, and the second carrier transport auxiliary layer 142 is in contact with the light emitting layer 13. The second carrier transport auxiliary layer 142 is in direct contact with the light-emitting layer 13 so that the second carrier transport auxiliary layer 142 and the light-emitting layer 13 are stacked, and no other functional layer is provided between the second carrier transport auxiliary layer 142 and the light-emitting layer 13.

In the light emitting device 1 shown in fig. 3, when the material of the light emitting layer 13 is the third quantum dot, in order to promote electron-hole transport balance, in some embodiments of the present application, the absolute value of the difference between the bandgap energy of the first quantum dot and the bandgap energy of the third quantum dot is smaller than the absolute value of the difference between the bandgap energy of the second quantum dot and the bandgap energy of the third quantum dot, so that the hole injection level of the light emitting device 1 is raised more than the electron injection level.

It should be noted that, the comprehensive performance of the existing blue light QLED is far behind that of the red light QLED and the green light QLED, and the reason is that: the band gap energy of the blue quantum dot is higher than that of the red quantum dot and the green quantum dot, and compared with the red quantum dot and the green quantum dot, the blue quantum dot needs higher energy to emit light, so that the carrier injection of the blue light QLED is difficult, namely the hole injection and the electron injection are difficult, and the application and the development of the blue light QLED are limited. Based on the fact that the band gap energy of the green quantum dots is low, and the band gap energy difference between the green quantum dots and the blue quantum dots is smaller than the band gap energy difference between the red quantum dots and the blue quantum dots, the quantum dots obtained after the green quantum dots are subjected to white light irradiation treatment can be used as materials of the first carrier transmission auxiliary layer 141 and/or the second carrier transmission auxiliary layer 142, carrier injection difficulty of the blue light QLED can be reduced, carrier injection level of the blue light QLED is improved, and photoelectric performance and service life of the blue light QLED are improved.

It can be understood that the QLED may be a green QLED, and the corresponding third quantum dot is a green quantum dot, and the quantum dot obtained by white light irradiation treatment of the red quantum dot is used as the material of the first carrier transmission auxiliary layer 141 and/or the second carrier transmission auxiliary layer 142, so as to further improve the carrier injection level of the green QLED.

In order to obtain better photoelectric performance and service life, in some embodiments of the present application, with continued reference to fig. 1 to 3, the light emitting device 1 further includes a hole function layer 15, where the hole function layer 15 is disposed between the anode 11 and the light emitting layer 13. When the light emitting device 1 includes the first carrier transport auxiliary layer 141, the hole function layer 15 is disposed between the anode 11 and the first carrier transport auxiliary layer 141. The hole function layer 15 may have a single-layer structure or a stacked-layer structure, and the thickness of the hole function layer 15 is, for example, 10nm to 200nm.

With continued reference to fig. 1 to 3, when the hole functional layer 15 includes a hole injection layer and/or a hole transport layer, and the light emitting device 1 includes the first carrier transport auxiliary layer 141, for the hole functional layer 15 including the hole injection layer 151 and the hole transport layer 152, the hole injection layer 151 is closer to the anode 11 than the first carrier transport auxiliary layer 141, and the hole transport layer 152 is closer to the first carrier transport auxiliary layer 141 than the hole injection layer 151.

The thickness of the hole injection layer 151 may be, for example, 10nm to 100nm. The material of the hole injection layer 151 includes, but is not limited to, crO _x 、MoS _x 、MoSe _x 、WS _x 、WSe _x CuS, poly (3, 4-ethylenedioxythiophene): at least one of poly (styrenesulfonic acid) (CAS number 155090-83-8), copper phthalocyanine (abbreviated as CuPc, CAS number 147-14-8), 2,3,5, 6-tetrafluoro-7, 7', 8' -tetracyanodimethyl-p-benzoquinone (abbreviated as F4-TCNQ, CAS number 29261-33-4), or 2,3,6,7,10, 11-hexacyano-1, 4,5,8,9, 12-hexaazabenzophenanthrene (abbreviated as HATCN, CAS number 105598-27-4).

The thickness of the hole transport layer 152 may be, for example, 10nm to 100nm. The material of hole transport layer 152 includes, but is not limited to, poly (9, 9-dioctylfluorene-CO-N- (4-butylphenyl) diphenylamine) (abbreviated as TFB, CAS No. 220797-16-0), 3-hexyl-substituted polythiophene (CAS No. 104934-50-1), poly (9-vinylcarbazole) (abbreviated as PVK, CAS No. 25067-59-8), poly [ bis (4-phenyl) (4-butylphenyl) amine](abbreviated as Poly-TPD, CAS number 472960-35-3), poly (N, N '-bis (4-butylphenyl) -N, N' -diphenyl-1, 4-phenylenediamine-CO-9, 9-dioctylfluorene) (abbreviated as PFB, CAS number 223569-28-6), 4',4 "-tris (carbazol-9-yl) triphenylamine (abbreviated as TCTA, CAS number 139092-78-7), 4' -bis (9-carbazole) biphenyl (abbreviated as CBP, CAS number 58328-31-7), N '-diphenyl-N, N' -bis (3-methylphenyl) -1,1 '-biphenyl-4, 4' -diamine (abbreviated as TPD, CAS number 65181-78-4), N '-diphenyl-N, N' - (1-naphthyl) -1,1 '-biphenyl-4, 4' -diamine (abbreviated as NPB, CAS number 123847-85-8), niO) _x 、WO _x 、MoO _x Or CuO.

In order to further enhance the optoelectronic performance and the service life of the light emitting device, in some embodiments of the present application, please continue to refer to fig. 1 to 3, the light emitting device 1 further includes an electronic functional layer 16, and the electronic functional layer 16 is disposed between the cathode 12 and the light emitting layer 13. When the light emitting device 1 includes the second carrier transport auxiliary layer 142, the electron functional layer 16 is disposed between the cathode 12 and the second carrier transport auxiliary layer 142. The electron functional layer 16 may have a single-layer structure or a stacked-layer structure, and the thickness of the electron functional layer 16 is, for example, 10nm to 120nm.

The electron functional layer 16 comprises an electron injection layer and/or an electron transport layer, and for an electron functional layer 16 comprising an electron injection layer and an electron transport layer, and the light emitting device 1 comprises a second carrier transport auxiliary layer 142, the electron injection layer is closer to the cathode 12 than the electron transport layer, and the electron transport layer is closer to the second carrier transport auxiliary layer 142 than the electron injection layer.

The thickness of the electron transport layer may be, for example, 10nm to 100nm. The material of the electron transport layer includes, but is not limited to, metal oxide, which may be undoped nano metal oxide or doped nano metal oxide, and the average particle size of the nano metal oxide may be, for example, 2nm to 15nm. In some embodiments of the present application, the nano metal oxide is selected from ZnO, tiO ₂ 、SnO ₂ 、BaO、Ta ₂ O ₃ 、ZrO ₂ At least one of TiLiO, znGaO, znAlO, znMgO, znSnO, znLiO, inSnO, alZnO, znOCl or ZnOF, it should be noted that, for doped nano metal oxides, the chemical formulas provided only show the elemental composition and not the content of the individual elements, for example: znMgO is composed of three elements, zn, mg and O.

The thickness of the electron injection layer may be, for example, 10nm to 100nm. The material of the electron injection layer includes, but is not limited to, at least one of an alkali metal halide including, but not limited to, liF, an alkali metal organic complex including, but not limited to, lithium 8-hydroxyquinoline, or an organic phosphine compound including, but not limited to, at least one of an organic phosphorus oxide, an organic thiophosphine compound, or an organic selenophosphine compound.

The embodiment of the application also provides a preparation method of the light-emitting device, wherein the light-emitting device is of a positive structure and comprises the following steps:

s1, providing an anode;

s2, forming a light-emitting layer on one side of the anode;

and S3, forming a cathode on one side of the light-emitting layer away from the anode.

Wherein the forming method of the anode, the light-emitting layer and the cathode comprises, but is not limited to, a solution method and a deposition method, wherein the solution method comprises, but is not limited to, at least one of spin coating, ink-jet printing, knife coating, dip-coating, dipping, spraying, roll coating or casting; the deposition method includes a chemical method including, but not limited to, at least one of a chemical vapor deposition method, a continuous ion layer adsorption and reaction method, an anodic oxidation method, an electrolytic deposition method, or a coprecipitation method, and a physical method including, but not limited to, at least one of a thermal evaporation plating method, an electron beam evaporation plating method, a magnetron sputtering method, a multi-arc ion plating method, a physical vapor deposition method, an atomic layer deposition method, or a pulsed laser deposition method.

In some embodiments of the present application, before step S2, the method for manufacturing a light emitting device further includes the steps of: s is S _a Providing a first quantum dot solution, applying the first quantum dot solution on one side of the anode, and then drying to obtain a first carrier transmission auxiliary layer, wherein the material of the first carrier transmission auxiliary layer comprises first quantum dots, and the light-emitting layer is formed on one side of the first carrier transmission auxiliary layer away from the anode, and the band gap energy of the first quantum dots is smaller than that of the material of the light-emitting layer.

In step S _a The first quantum dot solution is applied by at least one of spin coating, ink-jet printing, knife coating, dip-coating, dipping, spray coating, roll coating or casting. The "drying treatment" includes all processes capable of obtaining higher energy of the first quantum dot solution located at one side of the anode to be converted into a solid film, including but not limited to vacuum drying treatment and/or heat treatment including but not limited to a constant temperature heat treatment process or a non-constant temperature heat treatment (e.g., temperature is changed in a gradient) process, the temperature of the heat treatment may be, for example, 40 to 150 ℃, the temperature of the heat treatment may be, for example, 40 to 60 ℃, 60 to 80 ℃, 80 to 100 ℃, or 100 to 150 ℃, the temperature of the heat treatment is exemplified as constant 100 ℃.

To further increase the hole injection level, in some embodiments of the present application, the absolute value of the difference between the bandgap energy of the first quantum dot and the bandgap energy of the material of the light emitting layer is not higher than 0.6eV.

In order to both enhance the compactness of the first carrier transport auxiliary layer and facilitate injection of holes from the first carrier transport auxiliary layer to the light emitting layer 13, in some embodiments of the present application, the thickness of the first carrier transport auxiliary layer is 3nm to 8nm.

In some embodiments of the present application, the material of the light emitting layer is a third quantum dot.

In some embodiments of the present application, the third quantum dot has an emission wavelength of 400nm to 480nm, and/or the third quantum dot has a bandgap energy of 2.7eV to 2.9eV; and/or the band gap energy of the first quantum dot is 2.3eV to 2.5eV.

In some embodiments of the present application, a method of preparing a first quantum dot solution includes the steps of: providing a first luminescent quantum dot solution, wherein a solute of the first luminescent quantum dot solution is the first luminescent quantum dot, and performing white light irradiation treatment on the first luminescent quantum dot solution to convert the first luminescent quantum dot into the first quantum dot, so as to obtain the first quantum dot solution. Solvents for the first luminescent quantum dot solution include, but are not limited to, n-octane and/or n-heptane.

In some embodiments of the present application, the first luminescent quantum dot has a luminescent wavelength of 500nm to 560nm.

In order to improve the stability of the first carrier transport auxiliary layer, in some embodiments of the present application, the white light irradiation treatment is performed under the condition that the air humidity is 30% to 80% and the temperature is 5 ℃ to 40 ℃. The air humidity of the white light irradiation treatment may be, for example, 30% to 40%, 40% to 50%, 50% to 60%, 60% to 70%, or 70% to 80%, exemplified by 30%, 40%, 50%, 60%, 70%, or 80%; the temperature of the white light irradiation treatment may be, for example, 5 ℃ to 10 ℃, 10 ℃ to 20 ℃, 20 ℃ to 30 ℃, or 30 ℃ to 40 ℃, with 5 ℃, 10 ℃, 15 ℃, 20 ℃, 25 ℃, 30 ℃, 35 ℃, or 40 ℃ being exemplified.

In some embodiments of the present application, the illumination intensity of the white light irradiation treatment is 100lx to 5000lx, for example, may be 100lx to 500lx, 500lx to 1000lx, 1000lx to 2000lx, 2000lx to 3000lx, 3000lx to 4000lx, or 4000lx to 5000lx.

In some embodiments of the present application, the illumination time of the white light irradiation treatment is 1h to 10h, for example, may be 1h to 2h, 2h to 3h, 3h to 4h, 4h to 5h, 5h to 6h, 6h to 7h, 7h to 8h, 8h to 9h, or 9h to 10h.

In some embodiments of the present application, the illumination wavelength of the white light illumination treatment is 400nm to 760nm.

In some embodiments of the present application, after step S2 and before step S3, the method for manufacturing a light emitting device further includes the steps of: s is S _b Providing a second quantum dot solution, applying the second quantum dot solution on one side of the light-emitting layer far away from the anode, and then drying to obtain a second carrier transmission auxiliary layer, wherein the material of the second carrier transmission auxiliary layer comprises second quantum dots, and a cathode is formed on one side of the second carrier transmission auxiliary layer far away from the light-emitting layer, and the band gap energy of the second quantum dots is smaller than that of the material of the light-emitting layer.

In step S _b The second quantum dot solution is applied by at least one of spin coating, ink-jet printing, knife coating, dip-coating, dipping, spray coating, roll coating or casting.

To further increase the electron injection level, in some embodiments of the present application, the absolute value of the difference between the bandgap energy of the second quantum dot and the bandgap energy of the material of the light emitting layer is not higher than 0.6eV.

In order to both enhance the compactness of the second carrier transport auxiliary layer and facilitate electron injection from the second carrier transport auxiliary layer to the light emitting layer 13, in some embodiments of the present application, the thickness of the second carrier transport auxiliary layer is 3nm to 8nm.

In some embodiments of the present application, the third quantum dot has an emission wavelength of 400nm to 480nm, and/or the third quantum dot has a bandgap energy of 2.7eV to 2.9eV; and/or the band gap energy of the second quantum dot is 2.3eV to 2.5eV.

In some embodiments of the present application, a method of preparing a second quantum dot solution includes the steps of: providing a second luminescent quantum dot solution, wherein the solute of the second luminescent quantum dot solution is the second luminescent quantum dot, and performing white light irradiation treatment on the second luminescent quantum dot solution to convert the second luminescent quantum dot into the second quantum dot, so as to obtain the second quantum dot solution. The solvent of the second luminescent quantum dot solution includes, but is not limited to, n-octane and/or n-heptane. Wherein, the technological condition parameters of the white light irradiation treatment are described in the foregoing.

In some embodiments of the present application, the second luminescent quantum dot has a luminescent wavelength of 500nm to 560nm.

The embodiment of the application also provides a preparation method of the light-emitting device, wherein the light-emitting device is of an inverted structure and comprises the following steps:

s10, providing a cathode;

s20, forming a light-emitting layer on one side of the cathode;

and S30, forming an anode on one side of the light-emitting layer away from the cathode.

Wherein the method of forming the anode, the light emitting layer and the cathode is described with reference to the foregoing.

In some embodiments of the present application, the method for manufacturing a light emitting device further includes, before step S20: s is S _a Providing a second quantum dot solution, applying the second quantum dot solution on one side of the cathode, and then drying to obtain a second carrier transmission auxiliary layer, wherein the material of the second carrier transmission auxiliary layer comprises second quantum dots, and the light-emitting layer is formed on one side of the second carrier transmission auxiliary layer away from the cathode, and the band gap energy of the second quantum dots is smaller than that of the material of the light-emitting layer. The preparation method of the second quantum dot solution, the thickness of the second carrier transport auxiliary layer, and the materials of the second quantum dot and the light emitting layer are all described with reference to the foregoing.

In some embodiments of the present application, between step S20 and step S30, the method for manufacturing a light emitting device further includes the steps of: s is S _b Providing a first quantum dot solution, applying the first quantum dot solution on one side of the light-emitting layer far from the cathode, and drying to obtain a first carrier transmission auxiliary layer, wherein the material of the first carrier transmission auxiliary layer comprisesAnd the anode is formed on one side of the first carrier transmission auxiliary layer away from the light-emitting layer, and the band gap energy of the first quantum dots is smaller than that of the material of the light-emitting layer. The preparation method of the first quantum dot solution, the thickness of the first carrier transmission auxiliary layer, and the materials of the first quantum dot and the light emitting layer are all described with reference to the foregoing.

It is understood that the method of manufacturing the light emitting device may further comprise a step of manufacturing other film layers including, but not limited to, a solution method and a deposition method, for example, forming a hole function layer between the anode and the first carrier transport auxiliary layer, and/or forming an electron function layer between the cathode and the second carrier transport auxiliary layer. For example, when the light emitting device is of a positive structure, a hole function layer, a first carrier transport auxiliary layer, a light emitting layer, a second carrier transport auxiliary layer, an electron function layer, and a cathode are sequentially formed on one side of the anode. For another example, when the light emitting device is of an inverted structure, an electron functional layer, a second carrier transport auxiliary layer, a light emitting layer, a first carrier transport auxiliary layer, a hole functional layer, and an anode are sequentially formed on one side of the cathode.

The embodiment of the application also provides a display device, which comprises the light-emitting device or the light-emitting device manufactured by any one of the manufacturing methods. The display device may be any electronic product with a display function, including but not limited to a smart phone, a tablet computer, a notebook computer, a digital camera, a digital video camera, a smart wearable device, a smart weighing electronic scale, a vehicle-mounted display, a television set or an electronic book reader, wherein the smart wearable device may be, for example, a smart bracelet, a smart watch, a Virtual Reality (VR) helmet, etc.

The technical solutions and technical effects of the present application are described in detail below by means of specific examples, comparative examples and experimental examples, and the following examples are only some examples of the present application and are not intended to limit the present application in any way.

Example 1

The embodiment provides a light emitting device and a preparation method thereof, wherein the light emitting device is a quantum dot light emitting diode with a forward structure, as shown in fig. 1, in a bottom-up direction, the light emitting device 1 includes a substrate 10, an anode 11, a hole functional layer 15, a first carrier transport auxiliary layer 141, a light emitting layer 13, an electron functional layer 16 and a cathode 12, which are sequentially arranged, wherein the hole functional layer 15 includes a hole injection layer 151 and a hole transport layer 152 which are stacked, the hole injection layer 151 is close to the anode 11, the hole transport layer 152 is close to the first carrier transport auxiliary layer 141, and the electron functional layer 16 is an electron transport layer.

The materials and thicknesses of the layers in the light emitting device 1 are respectively:

the material of the substrate 10 is glass with the thickness of 1mm;

the anode 11 is made of ITO and has a thickness of 80nm;

the cathode 12 is made of Ag and has a thickness of 100nm;

the hole injection layer 151 is made of PEDOT: PSS with thickness of 25nm;

the hole transport layer 152 is made of TFB and has a thickness of 20nm;

the material of the first carrier transport auxiliary layer 141 is CdSe/ZnS quantum dots, the average particle diameter of the CdSe/ZnS quantum dots is 10nm, and the thickness of the first carrier transport auxiliary layer 141 is 4nm;

the luminescent layer 13 is made of CdZnSe/ZnS blue quantum dots, each 1mg of CdZnSe/ZnS blue quantum dots are correspondingly connected with 0.01mmol of oleic acid ligand, the average particle size of the CdZnSe/ZnS blue quantum dots is 8nm, the luminescent wavelength of the CdZnSe/ZnS blue quantum dots is 470nm, the peak width of the CdZnSe/ZnS blue quantum dots is 35nm, and the thickness of the luminescent layer 13 is 20nm;

the material of the electron functional layer 16 was nano ZnO having an average particle diameter of 5nm and a thickness of 50nm.

The preparation method of the light-emitting device in the embodiment comprises the following steps:

s1.1, providing a substrate, evaporating ITO on one side of the substrate to obtain an ITO layer, then sequentially ultrasonically cleaning the substrate containing the ITO by using acetone for 15min, a cleaning agent for 15min, deionized water for 15min and isopropanol for 15min, and performing surface treatment by using ultraviolet-ozone for 5min after drying to obtain the substrate containing an anode;

S1.2, spin coating PEDOT on one side of the anode far away from the substrate in an air environment at normal temperature and normal pressure: PSS aqueous solution (CAS number 155090-83-8), then heat-treating at 150deg.C for 15min to obtain hole injection layer;

s1.3, spin-coating TFB (CAS number 223569-31-1) -chlorobenzene solution on one side of the hole injection layer far away from the anode in the step S1.2 under the nitrogen environment of normal temperature and normal pressure, and then performing constant temperature heat treatment for 15min at 150 ℃ to obtain a hole transport layer;

s1.4, dispersing CdSe/ZnS green quantum dots (with the luminescence wavelength of 538nm and the half-width of 35 nm) with the average particle size in n-octane to prepare a first luminescence quantum dot solution with the concentration of 25mg/mL, then placing the first luminescence quantum dot solution in an environment with the air humidity of 50% and the temperature of 25 ℃ for white light irradiation treatment to obtain the first quantum dot solution, wherein the illumination intensity of the white light irradiation treatment is 1000lx, the illumination time is 24 hours, then spin-coating the first quantum dot solution on one side of the hole transmission layer far from the hole injection layer in the step S1.3 in a nitrogen environment with normal temperature and normal pressure, and then placing the first luminescence quantum dot solution in a constant temperature heat treatment for 5 minutes at 100 ℃ to obtain a first carrier transmission auxiliary layer;

s1.5, spin-coating a CdZnSe/ZnS blue quantum dot-n-octane solution with the concentration of 25mg/mL on one side of the first carrier transmission auxiliary layer far away from the hole transmission layer in the step S1.4 under the nitrogen environment of normal temperature and normal pressure, and then performing constant temperature heat treatment for 5min at 100 ℃ to obtain a luminescent layer;

S1.6, spin-coating a nano ZnO-ethanol solution with the concentration of 40mg/mL on one side of the luminescent layer far away from the first carrier transmission auxiliary layer in the step S1.5 under the nitrogen environment of normal temperature and normal pressure, and then performing constant temperature heat treatment for 10min at 80 ℃ to obtain an electron transmission layer;

s1.7, evaporating Ag on one side of the electron transport layer far away from the light-emitting layer in the step S1.6 to obtain a cathode, and packaging to obtain the light-emitting device.

Example 2

The present embodiment provides a light emitting device and a method for manufacturing the same, which are different from the light emitting device of embodiment 1 only in that: the thickness of the first carrier transport auxiliary layer was replaced with "8nm" from "4 nm".

The method of manufacturing the light-emitting device in this embodiment was performed with reference to embodiment 1.

Example 3

The present embodiment provides a light emitting device and a method for manufacturing the same, which are different from the light emitting device of embodiment 1 only in that: the thickness of the first carrier transport auxiliary layer was replaced with "10nm" from "4 nm".

Example 4

The present embodiment provides a light emitting device and a method for manufacturing the same, which are different from the light emitting device of embodiment 1 only in that: the thickness of the first carrier transport auxiliary layer was replaced with "2nm" from "4 nm".

Example 5

The present embodiment provides a light emitting device and a method of manufacturing the same, and the structural composition of the light emitting device in the present embodiment is the same as that of embodiment 1.

The manufacturing method of the light emitting device in this embodiment differs from that of embodiment 1 only in that: dispersing CdSe/ZnS green quantum dots (light emission wavelength 538nm and half-width 35 nm) having an average particle size of 10nm in n-octane to obtain a first light emission quantum dot solution having a concentration of 25mg/mL, then subjecting the first light emission quantum dot solution to white light irradiation treatment in an atmosphere having an air humidity of 50% and a temperature of 25 ℃ to obtain a first quantum dot solution, wherein the light intensity of the white light irradiation treatment is 1000lx, the light irradiation time is 24 hours "instead of" dispersing CdSe/ZnS green quantum dots (light emission wavelength 538nm and half-width 35 nm) having an average particle size of 10nm in n-octane to obtain a first light emission quantum dot solution having a concentration of 25mg/mL, and then subjecting the first light emission quantum dot solution to white light irradiation treatment in an atmosphere having an air humidity of 90% and a temperature of 60 ℃ to obtain a first quantum dot solution, wherein the light intensity of the white light irradiation treatment is 1000lx, and the light irradiation time is 24 hours.

Example 6

The present embodiment provides a light emitting device and a method for manufacturing the same, as shown in fig. 2, in a bottom-up direction, the light emitting device 1 includes a substrate 10, an anode 11, a hole function layer 15, a light emitting layer 13, a second carrier transport auxiliary layer 142, an electron function layer 16, and a cathode 12, which are sequentially disposed, wherein the hole function layer 15 includes a hole injection layer 151 and a hole transport layer 152 that are stacked, the hole injection layer 151 is close to the anode 11, the hole transport layer 152 is close to the light emitting layer 13, and the electron function layer 16 is an electron transport layer. The material and thickness of the second carrier transport auxiliary layer 142 are the same as those of the first carrier transport auxiliary layer in embodiment 1, and the material and thickness of the other layers are the same as those of embodiment 1.

s5.1, referring to the step S1.1;

s5.2, referring to the step S1.2;

s5.3, referring to the step S1.3;

s5.4, spin-coating a CdZnSe/ZnS blue quantum dot-n-octane solution with the concentration of 25mg/mL on one side of the hole transmission layer far away from the hole injection layer in the step S5.3 under the nitrogen environment of normal temperature and normal pressure, and then placing the solution in a constant temperature heat treatment for 5min at 100 ℃ to obtain a luminescent layer;

s5.5, dispersing CdSe/ZnS green quantum dots (with the luminescence wavelength of 538nm and the half-width of 35 nm) with the average particle size in n-octane to prepare a second luminescence quantum dot solution with the concentration of 25mg/mL, then placing the second luminescence quantum dot solution in an environment with the air humidity of 50% and the temperature of 25 ℃ for white light irradiation treatment to obtain the second quantum dot solution, wherein the illumination intensity of the white light irradiation treatment is 1000lx, the illumination time is 24 hours, then spin-coating the second quantum dot solution on one side of the luminescence layer far away from the hole transport layer in the step S5.4 in a nitrogen environment with normal temperature and normal pressure, and then placing the second luminescence quantum dot solution in a constant temperature heat treatment for 5 minutes at 100 ℃ to obtain a second carrier transport auxiliary layer;

S5.6, spin-coating a nano ZnO-ethanol solution with the concentration of 40mg/mL on one side of the second carrier transmission auxiliary layer far away from the light-emitting layer in the step S5.5 under the nitrogen environment of normal temperature and normal pressure, and then performing constant-temperature heat treatment for 10min at 80 ℃ to obtain an electron transmission layer;

s5.7, refer to step S1.7.

Example 7

The embodiment provides a light emitting device and a preparation method thereof, wherein the light emitting device is a quantum dot light emitting diode with a forward structure, as shown in fig. 3, in a bottom-up direction, the light emitting device 1 includes a substrate 10, an anode 11, a hole functional layer 15, a first carrier transport auxiliary layer 141, a light emitting layer 13, a second carrier transport auxiliary layer 142, an electron functional layer 16 and a cathode 12, which are sequentially disposed, wherein the hole functional layer 15 includes a hole injection layer 151 and a hole transport layer 152 which are stacked, the hole injection layer 151 is close to the anode 11, the hole transport layer 152 is close to the first carrier transport auxiliary layer 141, and the electron functional layer 16 is an electron transport layer. The material of the first carrier transport auxiliary layer 141 is the same as that of embodiment 1, and the thickness of the first carrier transport auxiliary layer 141 is 3nm; the material of the second carrier transport auxiliary layer 142 is the same as that of the first carrier transport auxiliary layer in embodiment 1, and the thickness of the second carrier transport auxiliary layer 142 is 3nm; the other layers were the same as in example 1 in material and thickness.

The manufacturing method of the light emitting device in this embodiment differs from that of embodiment 1 only in that: a step of dispersing CdSe/ZnS green quantum dots having an average particle diameter of 10nm (light emission wavelength of 538nm and a half-width of 35 nm) in n-octane to obtain a second light emission quantum dot solution having a concentration of 25mg/mL, then subjecting the second light emission quantum dot solution to a white light irradiation treatment in an atmosphere having an air humidity of 50% and a temperature of 25 ℃ to obtain a second quantum dot solution, the white light irradiation treatment having an irradiation intensity of 1000lx and an irradiation time of 24 hours, then spin-coating the second quantum dot solution on a side of the light emission layer of step S5.4 remote from the hole transport layer in a nitrogen atmosphere at normal temperature and normal pressure, and then subjecting to a constant temperature heat treatment at 100 ℃ for 5 minutes to obtain a second carrier transport auxiliary layer was added between step S1.6 and step S1.7.

Example 8

The present embodiment provides a light emitting device and a method for manufacturing the same, which are different from the light emitting device of embodiment 7 only in that: the material of the light-emitting layer is replaced by 'ZnSe blue quantum dots', 0.01mmol of oleic acid ligand is correspondingly connected to each 1mg of ZnSe blue quantum dots, the average grain diameter of the ZnSe blue quantum dots is 9nm, the light-emitting wavelength of the ZnSe blue quantum dots is 470nm and the peak width is 35nm ', and the materials of the first carrier transmission auxiliary layer and the second carrier transmission auxiliary layer are replaced by' CdSe (inner core)/CdS (middle shell)/ZnS quantum dots (outer shell), and the average grain diameter of the CdSe/CdS/ZnS quantum dots is 12 nm.

The manufacturing method of the light emitting device in this embodiment differs from that of embodiment 1 only in that: replacing step S1.4 with "dispersing CdSe/CdS/ZnS green quantum dots with average particle diameter of 12nm (light emitting wavelength of 538nm and half-width of 35 nm) in n-octane to obtain a first luminescent quantum dot solution with concentration of 25mg/mL, then subjecting the first luminescent quantum dot solution to white light irradiation treatment in an atmosphere with air humidity of 50% and temperature of 25 ℃ to obtain a first quantum dot solution, irradiating with light with an irradiation intensity of 1000lx for 24 hours, then spin-coating the first quantum dot solution on a side of the hole transporting layer of step S1.3 away from the hole injecting layer in nitrogen atmosphere at normal temperature and normal pressure, then subjecting to constant temperature heat treatment at 100 ℃ for 5min to obtain a first carrier transporting auxiliary layer", and adding step "dispersing CdSe/CdS/ZnS green quantum dots with average particle diameter of 12nm in n-octane between step S1.6 and step S1.7, to prepare a second luminescent quantum dot solution with the concentration of 25mg/mL, then placing the second luminescent quantum dot solution in an environment with the air humidity of 50% and the temperature of 25 ℃ for white light irradiation treatment to obtain the second quantum dot solution, wherein the illumination intensity of the white light irradiation treatment is 1000lx, the illumination time is 24 hours, then spin-coating the second quantum dot solution on one side of the luminescent layer of the step S5.4 far away from the hole transmission layer in a nitrogen environment with normal temperature and normal pressure, then placing the second quantum dot solution in a heat treatment with the constant temperature of 100 ℃ for 5 minutes to obtain a second carrier transmission auxiliary layer, and replacing the step S1.5 with the step S1.5 to spin-coating the ZnSe blue quantum dot-n-octane solution with the concentration of 25mg/mL on one side of the first carrier transmission auxiliary layer of the step S1.4 far away from the hole transmission layer in a nitrogen environment with normal temperature and normal pressure, then placing the second quantum dot solution in a heat treatment with the constant temperature of 100 ℃ for 5 minutes, a light-emitting layer was obtained.

Comparative example 1

The present comparative example provides a light emitting device and a method of manufacturing the same, which differs from the light emitting device of example 1 only in that: the first carrier transport auxiliary layer is omitted.

The preparation method of this comparative example differs from that of example 1 only in that: step S1.5 is omitted.

Comparative example 2

The present comparative example provides a light emitting device and a method of manufacturing the same, in which the structural composition of the light emitting device is the same as that of example 7.

The preparation method of this comparative example differs from that of example 7 only in that: the preparation step of the first carrier transmission auxiliary layer is replaced by spin coating CdSe/ZnS green quantum dot-n-octane solution with the concentration of 25mg/mL on one side of the hole transmission layer far away from the hole injection layer under the nitrogen environment of normal temperature and normal pressure, and then placing the solution in a constant temperature heat treatment for 5min at 100 ℃ to obtain the first carrier transmission auxiliary layer; and replacing the preparation step of the second carrier transmission auxiliary layer with spin-coating CdSe/ZnS green quantum dot-n-octane solution with the concentration of 25mg/mL on one side of the light-emitting layer far away from the hole transmission layer under the nitrogen environment of normal temperature and normal pressure, and then placing the solution in the constant temperature heat treatment for 5min at the temperature of 100 ℃ to obtain the second carrier transmission auxiliary layer.

Comparative example 3

The preparation method of this comparative example differs from that of example 7 only in that: and replacing the preparation step of the second carrier transmission auxiliary layer with spin-coating a CdSe/ZnS green quantum dot-n-octane solution with the concentration of 25mg/mL on one side of the light-emitting layer far away from the hole transmission layer in a nitrogen environment at normal temperature and normal pressure, and then placing the solution in a constant-temperature heat treatment mode at 100 ℃ for 5 minutes to obtain the second carrier transmission auxiliary layer.

Comparative example 4

The preparation method of this comparative example differs from that of example 7 only in that: the preparation step of the first carrier transmission auxiliary layer is replaced by 'spin coating CdSe/ZnS green quantum dot-n-octane solution with the concentration of 25mg/mL on one side of the hole transmission layer far away from the hole injection layer under the nitrogen environment at normal temperature and normal pressure', and then placing the solution in a constant temperature heat treatment for 5min at 100 ℃ to obtain the first carrier transmission auxiliary layer.

Experimental example

The performance of the light emitting devices of examples 1 to 8 and comparative examples 1 to 4 was tested using a friedel-crafts FPD optical property measuring device, which is an efficiency test system constructed by LabView controlled QE-PRO spectrometer, keithley 2400, and Keithley 6485, capable of measuring parameters such as voltage, current, luminance, light emission spectrum, etc. of the obtained light emitting device, and obtaining key parameters such as external quantum dot efficiency, power efficiency, etc. by calculation, and testing the service lives of the above-mentioned respective light emitting devices using a life test device.

The current efficiency testing method comprises the following steps: the light emitting area was set to 2mm×2mm=4mm ² The method comprises the steps of intermittently collecting the brightness value of a light-emitting device with the driving voltage in the range of 0V to 8V, collecting the brightness value at intervals of 0.2V at the initial brightness collecting voltage value of 3V, dividing the brightness value collected each time by the corresponding current density to obtain the current efficiency of the light-emitting device under the collecting condition, and obtaining the current efficiency under the brightness of 1000 nit. The service life testing method comprises the following steps: under the drive of constant current (2 mA), 128-path QLED life test system is adopted to perform electroluminescence on each light-emitting device The light lifetime analysis gave the time required for each light emitting device to decay from 100% to 95% at a luminance of 1000nit (t95@1000 nit, h). The electroluminescence patterns of the light emitting devices in example 7, comparative example 2 to comparative example 4 are shown in fig. 4.

The performance test data of each light emitting device is shown in table 1 below:

table 1 results of performance tests of light emitting devices of examples 1 to 8 and comparative examples 1 to 4

As can be seen from table 1, the overall performance of the light emitting devices of examples 1 to 8 has significant advantages over the light emitting devices of comparative examples 1 to 4, taking example 7 and comparative example 1 as examples, ce@1000mit of the light emitting device of example 7 is 1.8 times that of the light emitting device of comparative example 1, and t95@1000nit of the light emitting device of example 7 is 5.4 times that of the light emitting device of comparative example 1, thereby illustrating that: and a first carrier transmission auxiliary layer is additionally arranged between the anode of the QLED and the light-emitting layer, and/or a second carrier transmission auxiliary layer is additionally arranged between the cathode of the QLED and the light-emitting layer, so that the light-emitting efficiency and the service life of the QLED are improved.

As is clear from the performance test data of the light emitting devices in examples 1 to 4, the overall performance of the light emitting devices in examples 3 and 4 is inferior to that of the light emitting devices in examples 1 and 2, and therefore, the first carrier transport auxiliary layer has a suitable thickness to further improve the light emitting efficiency and the service life of the light emitting device, because: on the premise of ensuring that the first carrier transmission auxiliary layer has ideal compactness, the injection difficulty of carriers is reduced as much as possible. As is clear from examples 1 to 7, the thicknesses of the first carrier transport auxiliary layer and the second carrier transport auxiliary layer are selected from 3nm to 8nm independently of each other.

As can be seen from the performance test data of the light emitting devices in example 1 and example 5, the overall performance of the light emitting device in example 5 is inferior to that of the light emitting device in example 1, thereby explaining: in the preparation process of the blue QLED, the environment conditions for processing the CdSe/ZnS green quantum dot-n-octane solution by white light irradiation to obtain the first quantum dot solution are different, the comprehensive performance of the finally prepared blue QLED is greatly different, and the light-emitting efficiency and the service life of the blue QLED can be further improved by performing white light irradiation under the conditions that the air humidity is 30-80% and the temperature is 5-40 ℃.

As can be seen from the performance detection data of the light emitting devices in embodiments 1 to 8, the light emitting device in embodiment 7 has the optimal overall performance, and the light emitting device in embodiment 8 further has the improved light emitting efficiency and the improved service life compared to the light emitting device only including the first carrier transport auxiliary layer or the second carrier transport auxiliary layer.

As can be seen from the performance detection data of the light emitting devices in example 7 and comparative examples 2 to 4 and fig. 4, omitting the white light irradiation treatment step during the preparation process of the blue QLED results in a green light emission peak during the operation of the blue QLED, which negatively affects the light emission quality of the blue QLED, and in addition, reduces the carrier transmission performance of the first carrier transmission auxiliary layer and/or the second carrier transmission auxiliary layer, which further makes the overall performance of the blue QLED undesirable.

The light emitting device, the method for manufacturing the light emitting device and the display device provided in the embodiments of the present application are described in detail above. The principles and embodiments of the present application are described herein with reference to specific examples, the description of which is only for aiding in understanding the technical solution of the present application and its core ideas; those of ordinary skill in the art will appreciate that: the technical scheme described in the foregoing embodiments can be modified or some technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the scope of the corresponding technical solutions of the embodiments of the present application.

Claims

1. A light emitting device, comprising:

an anode;

a cathode disposed opposite the anode; and

a light-emitting layer disposed between the anode and the cathode;

the light emitting device further includes:

2. The light-emitting device according to claim 1, wherein an absolute value of a difference between a band gap energy of the first quantum dot and a band gap energy of a material of the light-emitting layer is not higher than 0.6eV;

3. The light-emitting device according to claim 1, wherein the first carrier transport auxiliary layer does not emit light and/or the second carrier transport auxiliary layer does not emit light in an operation state of the light-emitting device.

4. The light-emitting device according to claim 1, wherein the first quantum dot is a quantum dot obtained by subjecting a first light-emitting quantum dot to white light irradiation treatment;

5. The light-emitting device according to claim 1, wherein a thickness of the first carrier transport auxiliary layer is 3nm to 8nm, and/or a thickness of the second carrier transport auxiliary layer is 3nm to 8nm.

6. The light-emitting device according to claim 1, wherein the material of the light-emitting layer is selected from an organic light-emitting material or a third quantum dot;

the organic luminescent material is at least one selected from a diaryl anthracene derivative, a stilbene aromatic derivative, a pyrene derivative or a fluorene derivative, a TBPe fluorescent material, a TTPA fluorescent material, a TBRb fluorescent material or a DBP fluorescent material;

the material of the single component quantum dot, the material of the core-shell structure quantum dot and the material of the shell of the core-shell structure quantum dot are selected from at least one of II-VI compound, III-V compound, IV-VI compound or I-III-VI compound independently of each other, wherein the II-VI compound is selected from at least one of CdS, cdSe, cdTe, znS, znSe, znTe, znO, hgS, hgSe, hgTe, cdSeS, cdSeTe, cdSTe, znSeS, znSeTe, znSTe, hgSeS, hgSeTe, hgSTe, cdZnS, cdZnSe, cdZnTe, cdHgS, cdHgSe, cdHgTe, hgZnS, hgZnSe, hgZnTe, cdZnSeS, cdZnSeTe, cdZnSTe, cdHgSeS, cdHgSeTe, cdHgSTe, hgZnSeS, hgZnSeTe or HgZnSTe, and the III-V compound is selected from GaN, gaP, gaAs, gaSb, alN, alP, alAs, alSb, inN, inP, inAs, inSb, gaNP, gaNAs, gaNSb, gaPAs, gaPSb, alNP, alNAs, alNSb, alPAs, alPSb, inNP, inNAs, inNSb, inPAs, inPSb, gaAlNP, gaAlNAs, gaAlNSb, gaAlPAs, gaAlPSb, gaInNP, gaInNAs, gaInNS b. GaInPAs, gaInPSb, inAlNP, inAlNAs, inAlNSb, inAlPAs or InAlPSb, the IV-VI compound is selected from SnS, snSe, snTe, pbS, pbSe, pbTe, snSeS, snSeTe, snSTe, pbSeS, pbSeTe, pbSTe, snPbS, snPbSe, snPbTe, snPbSSe, snPbSeTe or SnPbSTe, and the I-III-VI compound is selected from CuInS ₂ 、CuInSe ₂ Or AgInS ₂ At least one of them.

7. The light-emitting device according to claim 6, wherein a material of the first carrier transport auxiliary layer is a first quantum dot and/or a material of the second carrier transport auxiliary layer is a second quantum dot;

and the material of the light-emitting layer is a third quantum dot.

8. The light-emitting device according to claim 7, wherein the third quantum dot has a band gap energy of 2.7eV to 2.9eV;

9. The light-emitting device according to claim 7, wherein for the light-emitting device including the first carrier transport auxiliary layer and the second carrier transport auxiliary layer, an absolute value of a difference between band gap energy of the first quantum dot and band gap energy of the third quantum dot is smaller than an absolute value of a difference between band gap energy of the second quantum dot and band gap energy of the third quantum dot.

10. The light-emitting device according to claim 1, wherein the first carrier-transporting auxiliary layer is provided in a stacked manner with the light-emitting layer, and wherein the first carrier-transporting auxiliary layer is in contact with the light-emitting layer;

11. A light-emitting device according to any one of claims 1 to 10, further comprising: a hole function layer disposed between the anode and the light emitting layer;

12. The light-emitting device according to claim 11, wherein the hole transport layer is made of a material selected from NiO _x 、WO _x 、MoO _x CuO, poly (9, 9-dioctylfluorene-CO-N- (4-butylphenyl) diphenylamine), 3-hexyl-substituted polythiophene, poly (9-vinylcarbazole), poly [ bis (4-phenyl) (4-butylphenyl) amine]At least one of poly (N, N '-bis (4-butylphenyl) -N, N' -diphenyl-1, 4-phenylenediamine-CO-9, 9-dioctylfluorene), 4',4 "-tris (carbazol-9-yl) triphenylamine, 4' -bis (9-carbazol) biphenyl, N '-diphenyl-N, N' -bis (3-methylphenyl) -1,1 '-biphenyl-4, 4' -diamine or N, N '-diphenyl-N, N' - (1-naphthyl) -1,1 '-biphenyl-4, 4' -diamine;

13. A light-emitting device according to any one of claims 1 to 10, further comprising: an electron functional layer disposed between the cathode and the light emitting layer;

when the second carrier transmission auxiliary layer is arranged between the cathode and the light-emitting layer, the electronic function layer is arranged between the cathode and the second carrier transmission auxiliary layer;

14. The light-emitting device according to claim 13, wherein the material of the electron transport layer comprises a metal oxide selected from ZnO, tiO ₂ 、SnO ₂ 、BaO、Ta ₂ O ₃ 、ZrO ₂ At least one of TiLiO, znGaO, znAlO, znMgO, znSnO, znLiO, inSnO, alZnO, znOCl, znOF or ZnMgLiO;

15. The preparation method of the light-emitting device is characterized in that the light-emitting device is of a positive structure and comprises the following steps:

providing an anode;

forming a light emitting layer on one side of the anode; and

forming a cathode on a side of the light emitting layer away from the anode;

16. The preparation method of the light-emitting device is characterized in that the light-emitting device is of an inverted structure and comprises the following steps:

providing a cathode;

forming a light emitting layer on one side of the cathode; and

forming an anode on a side of the light emitting layer away from the cathode;

17. The method of manufacturing according to claim 15 or 16, wherein an absolute value of a difference between the band gap energy of the first quantum dot and the band gap energy of the material of the light emitting layer is not higher than 0.6eV;

and/or the material of the light-emitting layer is a third quantum dot.

18. The method of claim 17, wherein the third quantum dot has a light emission wavelength of 400nm to 480nm and/or the third quantum dot has a band gap energy of 2.7eV to 2.9eV;

and/or the band gap energy of the first quantum dot is 2.3eV to 2.5eV;

and/or the band gap energy of the second quantum dot is 2.3eV to 2.5eV.

19. The method of preparing the first quantum dot solution according to claim 15 or 16, comprising the steps of: providing a first luminescent quantum dot solution, wherein a solute of the first luminescent quantum dot solution is a first luminescent quantum dot, and performing white light irradiation treatment on the first luminescent quantum dot solution to convert the first luminescent quantum dot into the first quantum dot, so as to obtain the first quantum dot solution;

20. The method of claim 19, wherein the first luminescent quantum dot has a luminescence wavelength of 500nm to 560nm;

21. The method according to claim 19, wherein the white light irradiation treatment is performed under conditions of an air humidity of 30% to 80% and a temperature of 5 ℃ to 40 ℃;

22. A display device characterized in that it comprises the light-emitting device according to any one of claims 1 to 14 or the light-emitting device produced by the production method according to any one of claims 15 to 21.