WO2023125072A1 - Light-emitting diode and preparation method therefor - Google Patents

Abstract

The present application relates to the field of optoelectronic technology and discloses a light-emitting diode and a preparation method therefor. The light-emitting diode comprises: a composite electron transport layer, materials thereof comprising an electron transport material and a metal salt, and a metal element in the metal salt being selected from the Group VIII elements; and a metal layer; a material of the metal layer being a doped or undoped metal elementary substance, and a metal element in the metal elementary substance being selected from the Group VIII elements. The light-emitting diode has a higher brightness and efficiency.

Description

A kind of light-emitting diode and its preparation method

This application claims the priority of the Chinese patent application with the application number 202111640141.6 and the application title "A Light-Emitting Diode and Its Preparation Method" filed at the China Patent Office on December 29, 2021, the entire contents of which are hereby incorporated by reference In this application.

technical field

The present application relates to the field of optoelectronic technology, in particular to a light emitting diode and a preparation method thereof.

Background technique

As a new type of display lighting technology, light-emitting diode technology has good energy saving, reliability, safety and environmental friendliness, so it has broad development prospects and is still one of the important research directions of display lighting.

Under the current technology, the main structure of a light emitting diode includes a cathode, an anode, a hole transport layer, an electron transport layer and a light emitting layer. The light-emitting diode with cathode, anode, hole transport layer, electron transport layer and light-emitting layer structure has not yet reached an ideal value in terms of brightness, efficiency and lifetime.

Due to the low transmittance of each film layer material (such as the electron transport layer material) of the light-emitting diode, the light emitted by the light-emitting layer will cause non-dissipative loss due to the light absorption of the film in the direction of its exit, resulting in the brightness of the light-emitting diode and Efficiency drops.

technical solution

The application provides a light emitting diode and a preparation method thereof.

The application provides a light emitting diode, including:

an anode, a cathode, and a light-emitting layer arranged between the anode and the cathode;

A composite electron transport layer, the composite electron transport layer is arranged between the cathode and the light-emitting layer, the material of the composite electron transport layer includes an electron transport material and a metal salt, and the metal elements in the metal salt are selected from group VIII elements; and

A metal layer, the metal layer is arranged between the cathode and the composite electron transport layer, the material of the metal layer is doped or undoped metal element, and the metal elements in the metal element are selected from group VIII elements.

Optionally, in some embodiments of the present application, in the composite electron transport layer, the ratio of the amount of the metal salt to the electron transport material is 0.04˜0.1.

Optionally, in some embodiments of the present application, the ratio of the amount of the metal element to the amount of the electron transport material is 0.02-0.033.

Optionally, in some embodiments of the present application, the metal salt is selected from one or more of ferric chloride, cobalt chloride, ferric acetate, cobalt acetate, ferric stearate, ferric nitrate, and cobalt nitrate.

Optionally, in some embodiments of the present application, the metal element is selected from one or more of nickel, palladium, and platinum.

Optionally, in some embodiments of the present application, the doping element in the doped metal element is selected from group VIII elements, and the doping element is different from the metal element in the metal element.

Optionally, in some embodiments of the present application, the electron transport material is selected from one or more of doped or undoped semiconductor nanoparticles and organic electron transport materials.

Optionally, in some embodiments of the present application, the electron transport material is selected from doped or undoped TiO ₂ , ZnO, ZrO, SnO ₂ , WO ₃ , Ta ₂ O ₃ , HfO ₃ , Al ₂ O _3. One or more of ZrSiO ₄ , BaTiO ₃ , BaZrO ₃ , CdS, ZnSe, and ZnS.

Optionally, in some embodiments of the present application, the doping elements of the electron transport material are selected from one or more of Al, Mg, In, Li, Ga, Cd, Cs, and Cu.

Optionally, in some embodiments of the present application, the light emitting diode is one of a light emitting diode with an upright structure and a light emitting diode with an inverted structure.

Optionally, in some embodiments of the present application, the light emitting diode is one of quantum dot light emitting diodes, organic light emitting diodes, and micron light emitting diodes.

Optionally, in some embodiments of the present application, the quantum dot light-emitting diode includes a quantum dot light-emitting layer; the material of the quantum dot light-emitting layer is selected from CdSe, CdS, ZnSe, ZnS, CdTe, ZnTe, CdZnS, CdZnSe, CdZnTe, ZnSeS, ZnSeTe, ZnTeS, CdSeS, CdSeTe, CdTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdSeSTe, ZnSeSTe, CdZnSeSTe, CdSe/ZnS, CdZnSe/ZnS, CdS/CdZnS, InP, InAs, InAsP, InP/InAsP, PbS, Pb Se, One or more of PbTe, PbSeS, PbSeTe, PbSTe, PbSe/PbS.

In addition, a method for preparing a light-emitting diode, comprising:

provide the anode;

forming a light-emitting layer on the anode;

Depositing and forming a laminated composite electron transport layer and metal layer on the light emitting layer;

forming a cathode on the metal layer;

Wherein, the material of the composite electron transport layer includes an electron transport material and a metal salt, and the metal elements in the metal salt are selected from group VIII elements;

The material of the metal layer is doped or undoped metal element, and the metal element in the metal element is selected from group VIII elements.

Optionally, in some embodiments of the present application, the above steps of depositing and forming a laminated composite electron transport layer and metal layer include:

Deposit the electron transport material on the light-emitting layer, and before the film layer of the electron transport material is solidified, deposit the metal salt on the film layer of the electron transport material, obtain the film layer of the electron transport material deposited with the metal salt, and solidify to form a composite electron transport layer ;

A metal layer is formed by depositing a metal element on the composite electron transport layer.

Optionally, in some embodiments of the present application, the above curing to form the composite electron transport layer is achieved by exposing the film layer of the electron transport material deposited with the metal salt to the air, and the way of exposure to the air includes exposing the film layer of the electron transport material deposited with the metal salt to the air. The electron transport material film layer is placed in the air environment for 0.25~1min.

Optionally, in some embodiments of the present application, the above-mentioned curing to form a composite electron transport layer is realized by ultraviolet light irradiation, and the ultraviolet light irradiation method includes utilizing ultraviolet light to irradiate an electron transport material film layer deposited with a metal salt for 0.25~ 30min.

In addition, a method for preparing a light-emitting diode, comprising:

provide the cathode;

Depositing a laminated metal layer and composite electron transport layer on the cathode;

forming a light emitting layer on the composite electron transport layer;

forming an anode on the light-emitting layer;

Wherein, the material of the composite electron transport layer includes an electron transport material and a metal salt, and the metal elements in the metal salt are selected from group VIII elements;

The material of the metal layer is doped or undoped metal element, and the metal element in the metal element is selected from group VIII elements.

Optionally, in some embodiments of the present application, the above steps of depositing and forming the stacked metal layer and the composite electron transport layer include:

Depositing a metal element on the cathode to form a metal layer;

Metal salt is deposited on the metal layer, and before the film layer of the metal salt is solidified, an electron transport material is deposited on the film layer of the metal salt to obtain a film layer of the metal salt deposited with the electron transport material, which is cured to form a composite electron transport layer.

Optionally, in some embodiments of the present application, the above-mentioned curing to form a composite electron transport layer is achieved by exposing the metal salt film layer deposited with the electron transport material to the air. The metal salt film layer of the material is placed in the air environment for 0.25~1min.

Optionally, in some embodiments of the present application, the above-mentioned curing to form the composite electron transport layer is realized by ultraviolet light irradiation, and the ultraviolet light irradiation method includes 0.25~ 30min.

Compared with the prior art, the light-emitting diode provided by this application includes a composite electron transport layer formed by metal salts of Group VIII metals and electron transport materials. The composite electron transport layer has a higher film transmittance, and the defects in the film layer Less, can effectively reduce the probability of the outgoing light being absorbed by defects, thereby enhancing the device transmittance of the light emitting diode. In addition, in the light-emitting diode of the present application, a metal layer including Group VIII elements laminated with the above-mentioned composite electron transport layer is provided. The metal layer has high electrical conductivity, and can effectively balance the increase caused by the introduction of the metal salt of the above-mentioned Group VIII metal. High sheet resistance is conducive to the transport of carriers and improves device efficiency. The composite electron transport layer and the metal layer in the light-emitting diode of the present application complement each other and cooperate with each other, so that the light-emitting diode of the present application has higher brightness and efficiency.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings that need to be used in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, other drawings can also be obtained based on these drawings without any creative effort.

FIG. 1 is a schematic structural view of a quantum dot light-emitting diode provided in Example 1 of the present application;

2 is a schematic flow diagram of a method for manufacturing a quantum dot light-emitting diode with an upright structure provided in Example 1 of the present application;

FIG. 3 is a schematic structural diagram of a quantum dot light-emitting diode provided in Embodiment 7 of the present application;

4 is a schematic flow diagram of a method for manufacturing a quantum dot light-emitting diode with an upright structure provided in Embodiment 7 of the present application;

Fig. 5 is a schematic structural diagram of a quantum dot light-emitting diode provided in Embodiment 8 of the present application;

FIG. 6 is a schematic flowchart of a method for manufacturing an inverted quantum dot light-emitting diode provided in Embodiment 8 of the present application.

Wherein, the reference numerals explain:

Substrate 110; anode 120; hole injection layer 130; hole transport layer 140; quantum dot light emitting layer 150; composite electron transport layer 160; electron transport material 161; metal salt 162; metal layer 170;

Embodiment of this application

The following will clearly and completely describe the technical solutions in the embodiments of the application with reference to the drawings in the embodiments of the application. Apparently, the described embodiments are only some of the embodiments of the application, not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts belong to the scope of protection of this application.

Embodiments of the present application provide a light emitting diode and a manufacturing method thereof. Each will be described in detail below. It should be noted that the description sequence of the following embodiments is not intended to limit the preferred sequence of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". The terms first, second, third, etc. are used for designation only and do not impose numerical requirements or establish an order.

In this application, expressions such as "one or more" refer to one or more of the listed items, and "multiple" refers to any combination of two or more of these items, including single items (species) ) or any combination of plural items (species), for example, “at least one (species) of a, b, or c” or “at least one (species) of a, b, and c” can mean: a ,b,c,a-b (that is, a and b),a-c,b-c, or a-b-c, where a,b,c can be single or multiple.

Various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the application; therefore, the described range should be regarded as The description has specifically disclosed all possible subranges as well as individual values within that range. For example, a description of a range from 0.04 to 0.1 should be considered to have specifically disclosed sub-ranges, such as from 0.04 to 0.05, from 0.05 to 0.06, from 0.06 to 0.07, from 0.07 to 0.09, etc., as well as a single number within the enumerated range, such as 0.04 , 0.05 and 0.06, this applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range.

The application provides a light emitting diode, including:

an anode, a cathode, and a light-emitting layer arranged between the anode and the cathode;

A composite electron transport layer, the composite electron transport layer is arranged between the cathode and the light-emitting layer, the material of the composite electron transport layer includes an electron transport material and a metal salt, and the metal elements in the metal salt are selected from group VIII elements; and

A metal layer, the metal layer is arranged between the cathode and the composite electron transport layer, the material of the metal layer is doped or undoped metal element, and the metal elements in the metal element are selected from group VIII elements.

In the present application, the composite electron transport layer containing the metal salt has higher transmittance, thereby making the light-emitting diode have higher brightness. At the same time, the metal layer stacked with the composite electron transport layer can effectively balance the sheet resistance and improve the efficiency of the light emitting diode. The above-mentioned stacking arrangement of the composite electron transport layer and the light-emitting layer is a stacking arrangement in a broad sense, that is, the composite electron transport layer can be directly in contact with the light-emitting layer and stacked, or there can be other film layers between the composite electron transport layer and the light-emitting layer. Case cascading settings.

Further, in the present application, the metal elements in the metal layer and the metal elements in the metal salt are elements of the same group (Group VIII), so the metal atoms in the metal layer and the metal atoms in the metal salt can have similar electron orbits.

In some embodiments, in the composite electron transport layer, the ratio of the amount of the metal salt to the electron transport material is 0.04˜0.1.

When the ratio of the amount of the metal salt to the electron transport material is within the above range, the transmittance of the composite electron transport layer can be effectively improved without excessively increasing the sheet resistance of the composite electron transport layer. Further, the ratio range of the amount of the metal salt to the electron transport material may also be a sub-range of the above range, for example, in some embodiments, the ratio of the amount of the metal salt to the electron transport material may be 0.05-0.1, or Can be 0.04~0.067.

In some embodiments, the ratio of the amount of the simple metal to the electron transport material is 0.02-0.033.

When the ratio of the amount of the simple metal to the electron transport material is within the above range, the sheet resistance of the composite electron transport layer can be effectively reduced while ensuring that the transmittance of the composite electron transport layer is not significantly reduced. In some embodiments, the ratio of the thickness of the film can be used to approximate the ratio of the amount of the substance.

Preferably, the metal salt is selected from one or more of ferric chloride, cobalt chloride, ferric acetate, cobalt acetate, ferric stearate, ferric nitrate and cobalt nitrate. Further, the above-mentioned iron acetate may be iron acetate monohydrate, and the above-mentioned cobalt acetate may be cobalt acetate tetrahydrate.

In some embodiments, the metal element may be selected from one or more of nickel, palladium, and platinum.

In some embodiments, the doping element of the doped metal element is selected from group VIII elements, and the doping element is different from the metal element in the metal element.

In some embodiments, the electron transport material is selected from one or more of doped or undoped semiconductor nanoparticles and organic electron transport materials. In at least some embodiments, the doped or undoped semiconductor nanoparticles are doped or undoped metal oxides.

Further, the electron transport material can be selected from doped or undoped TiO ₂ , ZnO, ZrO, SnO ₂ , WO ₃ , Ta ₂ O ₃ , HfO ₃ , Al ₂ O ₃ , ZrSiO ₄ , BaTiO ₃ , BaZrO _3. One or more of CdS, ZnSe, and ZnS.

In some embodiments, the doping elements of the electron transport material may be selected from one or more of Al, Mg, In, Li, Ga, Cd, Cs, and Cu.

In some embodiments, the light emitting diode is one of a light emitting diode with an upright structure and a light emitting diode with an inverted structure.

In some embodiments, the light emitting diode is one of quantum dot light emitting diode (QLED), organic light emitting diode (OLED), and micron light emitting diode (Micro LED). Further, the light-emitting diodes in this application can be quantum dot light-emitting diodes with upright or inverted structures, organic light-emitting diodes with upright or inverted structures, or micron light-emitting diodes with upright or inverted structures. . Preferably, the light emitting diode is a light emitting diode with a vertical structure. Further, the device structure of the light emitting diode in the present application may be one of a three-layer device, a multi-layer device, a top emitter device, a bottom emitter device, and a double-sided emitter device.

In some embodiments, the quantum dot light-emitting diode includes a quantum dot light-emitting layer; the material of the quantum dot light-emitting layer is selected from CdSe, CdS, ZnSe, ZnS, CdTe, ZnTe, CdZnS, CdZnSe, CdZnTe, ZnSeS, ZnSeTe, ZnTeS, CdSeS , CdSeTe, CdTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdSeSTe, ZnSeSTe, CdZnSeSTe, CdSe/ZnS, CdZnSe/ZnS, CdS/CdZnS, InP, InAs, InAsP, InP/InAsP, PbS, PbSe, PbTe, PbSeS, PbSeTe, Pb STe , one or more of PbSe/PbS. The "/" in the above expressions such as CdSe/ZnS means that the substance after the "/" (as the shell layer) covers the substance before the "/" (as the core layer). Preferably, the material of the quantum dot light-emitting layer is selected from one of II-VI group semiconductor nanocrystals CdSe, CdS, ZnSe, CdS, PbS, PbS and a core-shell structure material composed of the above-mentioned II-VI group semiconductor nanocrystals or more.

The embodiment of the present application also provides a method for preparing a light-emitting diode. When preparing a light-emitting diode with a vertical structure, the above-mentioned preparation method includes:

provide the anode;

forming a light-emitting layer on the anode;

Depositing and forming a laminated composite electron transport layer and metal layer on the light emitting layer;

A cathode is formed on the metal layer.

Wherein, the material of the composite electron transport layer includes an electron transport material and a metal salt; the metal elements in the metal salt are selected from Group VIII elements.

The material of the metal layer is doped or undoped metal element, and the metal element in the metal element is selected from group VIII elements.

When preparing a light-emitting diode with an inverted structure, the above-mentioned preparation method includes:

provide the cathode;

Depositing a laminated metal layer and composite electron transport layer on the cathode;

forming a light emitting layer on the composite electron transport layer;

An anode is formed on the light emitting layer.

Wherein, the material of the composite electron transport layer includes an electron transport material and a metal salt; the metal elements in the metal salt are selected from group VIII elements.

The material of the metal layer is doped or undoped metal element, and the metal element in the metal element is selected from group VIII elements.

The above expression of depositing another film layer on the film layer (such as "forming a laminated composite electron transport layer and metal layer on the light-emitting layer") is a broad sense, meaning above or above, which can be on the film layer Another film layer can be directly deposited on the film layer, and another film layer can be formed on the film layer, and another film layer can be formed on the other film layer. Further, when the composite electron transport layer is deposited and formed by using the above preparation method of light-emitting diodes, the electron transport material and the metal salt can be mixed and deposited directly to form a composite electron transport layer, or the electron transport material and the metal salt can be deposited separately to form a composite electron transport layer. layer. Preferably, the composite electron transport layer is formed by separately depositing the electron transport material and the metal salt.

When the composite electron transport layer is formed by separately depositing the electron transport material and the metal salt, the deposition method is slightly different according to the structure of the light emitting diode device.

For example, when the device structure of the light emitting diode is an upright structure, the steps of depositing and forming the stacked composite electron transport layer and the metal layer include:

Deposit the electron transport material on the light-emitting layer, and before the film layer of the electron transport material is solidified, deposit the metal salt on the film layer of the electron transport material, obtain the film layer of the electron transport material deposited with the metal salt, and solidify to form a composite electron transport layer ;

A metal layer is formed by depositing a metal element on the composite electron transport layer.

And when the device structure of the light-emitting diode is an inverted structure, the steps of depositing and forming the stacked metal layer and the composite electron transport layer include:

Depositing a metal element on the cathode to form a metal layer;

Metal salt is deposited on the metal layer, and before the film layer of the metal salt is solidified, an electron transport material is deposited on the film layer of the metal salt to obtain a film layer of the metal salt deposited with the electron transport material, which is cured to form a composite electron transport layer.

However, whether it is to prepare a light-emitting diode with an upright structure or an light-emitting diode with an inverted structure, regarding the deposition of electron transport materials and metal salts, the materials deposited later should be deposited before the materials deposited earlier are not completely cured and formed into a separate film. On top of the deposited material, in this way, the later deposited material can penetrate into the thin film of the first deposited material, so that Group VIII metal elements can be introduced into the electron transport material crystallization stage to form a composite electron transport layer, reducing the probability of the outgoing light being absorbed by defects , to increase the transmittance.

When the composite electron transport layer is formed by separately depositing the electron transport material and the metal salt, the film layer of the deposited electron transport material and the film layer of the metal salt are not two completely independent film layers, and the film interface between the two There is material in the lower film layer that penetrates into the upper film layer. The metal salt of group VIII metal deposited between the electron transport material film layer and the metal elemental film layer can separate the metal layer from the independent electron transport material film layer, and play a role of interval protection, so that the material at the film layer interface The lattice gap between them is closer, and there are fewer defects at the film interface, so that most of the light can pass through the film interface without being absorbed, and the final brightness of the device is improved.

In some embodiments, in order to ensure that the first-deposited material is not fully cured when the later-deposited material is deposited, a non-high-temperature cross-linking operation may be used to cure and cross-link the first-deposited material. For example, when preparing a light-emitting diode with an upright structure, the above-mentioned curing to form a composite electron transport layer can be achieved by exposing the film layer of the electron transport material deposited with the metal salt to air and/or by irradiating ultraviolet light. Wherein, the manner of exposing the film layer of the electron transport material deposited with the metal salt to the air includes placing the film layer of the electron transport material deposited with the metal salt in an air environment for 0.25-1 min. The method of irradiating with ultraviolet light includes irradiating the film layer of the electron transport material deposited with the metal salt by ultraviolet light for 0.25-30 minutes.

When preparing a light-emitting diode with an inverted structure, the above-mentioned curing to form a composite electron transport layer can be achieved by exposing the metal salt film layer deposited with the electron transport material to air and/or by irradiating ultraviolet light. Among them, the method of exposing the metal salt to the air includes placing the metal salt film layer deposited with the electron transport material in the air environment for 0.25~1min; the method of ultraviolet light irradiation includes using ultraviolet light to irradiate the metal salt film deposited with the electron transport material Layer 0.25~30min.

The above-mentioned ultraviolet light irradiation method can be carried out under a protective gas (such as nitrogen, inert gas) atmosphere; the ultraviolet light source can vertically irradiate the device film; the wavelength of the above-mentioned ultraviolet light can be 240~260nm, preferably, the above-mentioned ultraviolet light The wavelength is 254nm.

Further, the film layer of the electron transport material deposited with the metal salt can be cured only by exposure to the air, or the film layer of the electron transport material deposited with the metal salt can be cured only by ultraviolet light irradiation, or exposed The film layer of the electron transport material deposited with the metal salt is solidified by irradiating ultraviolet light in the air. However, when the film layer of the electron transport material deposited with the metal salt is cured by exposing to air while irradiating with ultraviolet light, the time for exposing to air and irradiating with ultraviolet light should be appropriately shortened. For example, when the film layer of the electron transport material deposited with metal salt is cured by exposing to the air and irradiating ultraviolet light at the same time, the time for exposing to air and irradiating ultraviolet light can be 0.25~0.5min; When the film layer of the electron transport material deposited with the metal salt is cured in the air, the exposure time to the air can be 0.5~1min. When the film layer of the electron transport material deposited with the metal salt is cured only by ultraviolet light irradiation, The time of ultraviolet light irradiation can be 20~30min. Further, a quantum dot light emitting diode having a structure of anode/hole injection layer/hole transport layer/quantum dot light emitting layer/electron transport layer/cathode can be prepared by the above method for preparing light emitting diodes.

When preparing a quantum dot light-emitting diode with a structure of anode/hole injection layer/hole transport layer/quantum dot light-emitting layer/electron transport layer/cathode, the preparation method of the light-emitting diode may include:

depositing a hole injection layer on the substrate formed with the anode;

depositing a hole transport layer on the hole injection layer;

Depositing a quantum dot luminescent layer on the hole transport layer;

Depositing electron transport materials on the quantum dot light-emitting layer;

Depositing a metal salt before the film layer of the electron transport material is solidified to form a composite electron transport layer;

After the film layer of the metal salt to be deposited is solidified, a metal layer is deposited on the film layer of the metal salt;

forming a cathode on said metal layer; and

encapsulation.

Among them, the material of the anode can be selected from doped or undoped metal oxides, such as ITO, IZO, ITZO, ICO, SnO ₂ , In ₂ O ₃ , Cd:ZnO, F:SnO ₂ , In:SnO ₂ , Ga: SnO ₂ , AZO, etc.; can also be selected from metal materials, such as Ni, Pt, Au, Ag, Cu, Al, Ir; can also be metal materials containing CNT, etc. The ":" in the above expressions such as Cd:ZnO means doping. Preferably, the above-mentioned anode is an anode with an ITO/metal/ITO structure, the above-mentioned ITO is preferably indium-doped ITO, and the above-mentioned metal can be selected from one or more of Au, Ag, Al, and Cu.

The material of the hole injection layer can be selected from poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonic acid) (PEDOT:PSS) and its derivatives doped with s-MoO3 (PEDOT:PSS :s-MoO3), poly[9,9-dioctyl-fluorene-co-N-(4-butylphenyl)-diphenylamine] (TFB), poly(N-vinylcarbazole)( PVK), N,N,N',N'-tetrakis(4-methoxyphenyl)-benzidine (TPD), 4-bis[N-(1-naphthyl)-N-phenyl-amino] Biphenyl (α-NPD), 4,4',4''-tris[phenyl(m-tolyl)amino]triphenylamine (m-MTDATA), 4,4',4''-tris( N-carbazolyl)-triphenylamine (TCTA), 1,1-bis[(di-4-tolylamino)phenylcyclohexane (TAPC), doped with tetrafluoro-tetracyano-quinone 4,4',4''-tris(diphenylamino)triphenylamine (TDATA), p-doped phthalocyanine (e.g., F4-TCNQ-doped zinc phthalocyanine ( ZnPc)), F4-TCNQ doped N,N′-diphenyl-N,N′-di(1-naphthyl)-1,1′-biphenyl-4,4″-diamine (α- One or more of NPD), hexaazatriphenylene-hexanonitrile (HAT-CN). Preferably, the material of the hole layer can be selected from PEDOT:PSS or PEDOT:PSS:s-MoO ₃ One of.

The material of the hole transport layer can be selected from 4,4'-N,N'-dicarbazolyl-biphenyl (CBP), N,N'-diphenyl-N,N'-bis(1-naphthalene base)-1,1'-biphenyl-4,4''-diamine (α-NPD), poly N,N'-diphenyl-N,N'-bis(3-methylphenyl)- (1,1'-biphenyl)-4,4'-diamine (Poly-TPD), N,N'-bis(3-methylphenyl)-N,N'-bis(phenyl)- Spiro(spiro-TPD), N,N'-bis(4-(N,N'-diphenyl-amino)phenyl)-N,N'-diphenylbenzidine (DNTPD), 4,4' ,4'-tris(N-carbazolyl)-triphenylamine (TCTA), 4,4',4''-tris[phenyl(m-tolyl)amino]triphenylamine (m-MTDATA), Poly[(9,9'-dioctylfluorene-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl)diphenylamine))](TFB), Poly(4-butylphenyl-diphenylamine) (poly-TPD), poly(p-)phenylene vinylene and derivatives thereof such as poly(phenylene vinylene) (PPV), poly[ 2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene](MEH-PPV), poly[2-methoxy-5-(3',7 '-Dimethyloctyloxy)-1,4-phenylene vinylene] (MOMO-PPV), copper phthalocyanine (CuPc), aromatic tertiary amine or polynuclear aromatic tertiary amine, 4,4'-bis (p-carbazolyl)-1,1'-biphenyl compound, N,N,N',N'-tetraarylbenzidine (TPB), PEDOT:PSS and its derivatives, poly(N-vinylcarba azole) (PVK) and its derivatives, polymethacrylate (PMMA) and its derivatives, poly(9,9-octylfluorene) (PFO) and its derivatives, poly(spirofluorene) and its derivatives , N,N'-bis(naphthalen-1-yl)-N,N'-diphenylbenzidine (NPB). Preferably, the above-mentioned hole transport layer can be selected from one or more of TFB, PVK, Poly-TPD, and NPB.

The cathode material may be selected from Ca, Ba, Ca:Al, LiF:Ca, LiF:Al, BaF ₂ :Al, CsF:Al, CaCO ₃ :Al, BaF ₂ :Ca:Al, Al, Mg, Au:Mg , one or more of Ag:Mg. Preferably, the material of the cathode can be selected from Al and/or Ag.

The present application will be described in detail through specific examples below, and the following examples are only part of the examples of the present application, and are not intended to limit the present application.

Example 1

Referring to Fig. 1, the present embodiment provides a quantum dot light emitting diode, the device structure of the quantum dot light emitting diode is an upright structure, including: a substrate 110, an anode 120, a hole injection layer 130, a hole transport layer stacked in sequence layer 140 , quantum dot light emitting layer 150 , composite electron transport layer 160 , metal layer 170 and cathode 180 . Wherein, the material of the composite electron transport layer 160 includes an electron transport material 161 and a metal salt 162 , and the metal salt 162 is infiltrated into the electron transport material 161 (shown in the form of a curve in FIG. 1 ).

Referring to Fig. 2, the present embodiment also provides the preparation method of the above-mentioned quantum dot light-emitting diode, including:

S111: providing a substrate 110, and preparing an anode 120 having an ITO/Ag/ITO structure on the substrate 110;

S112: Spin-coat PEDOT:PSS:s-MoO ₃ on the anode 120 to prepare a hole injection layer 130 with a thickness of 20 nm, and anneal the hole injection layer 130 in air at 180° C. for 15 minutes;

S113: In a nitrogen atmosphere, spin-coat poly-TPD on the hole injection layer 130 to prepare a hole transport layer 140 with a thickness of 15 nm, and anneal at 150° C. for 15 minutes;

S114: Spin-coat CdSe/ZnS on the hole transport layer 140 to prepare a quantum dot light-emitting layer 150 with a thickness of 50 nm, and anneal at 85° C. for 15 minutes;

S115: Spin-coat LZO on the quantum dot light-emitting layer 150 to prepare a film layer of the electron transport material 161 with a thickness of 60 nm, and irradiate the obtained device vertically with 254 nm UV for 20 minutes in a nitrogen environment;

S116: before the film layer of the electron transport material 161 is completely cured, spin-coat FeCl ₃ on the film layer of the electron transport material 161 to prepare a film layer of the metal salt 162 with a thickness of 3 nm, and anneal at 80° C. for 15 minutes;

S117: After the film layer of the metal salt 162 is completely cured, evaporate Ni on the deposited film layer of the metal salt 162 to prepare a metal layer 170 with a thickness of 2 nm;

S118: evaporating Ag on the metal layer 170 to form a cathode 180 with a thickness of 80 nm;

S119: Encapsulation.

In addition, this embodiment provides an optical transmittance testing device and a preparation method thereof. Wherein, the preparation method of the optical transmittance test device includes:

Spin-coat LZO on ITO to prepare a film layer of electron transport material 161 with a thickness of 60nm and irradiate the device vertically with 254nm UV for 20 minutes in a nitrogen environment. Spin-coat FeCl ₃ on the film layer of 161 to prepare a film layer of metal salt 162 with a thickness of 3nm and anneal at 80°C for 15 minutes, then completely solidify the film layer of metal salt 162, and combine with the film layer of electron transport material 161 After the composite electron transport layer 160 is formed, Ni is vapor-deposited on the film layer of the metal salt 162 to prepare a metal layer with a thickness of 2 nm.

Example 2

The embodiment of the present application provides a quantum dot light-emitting diode and a preparation method thereof. On the basis of embodiment 1, the quantum dot light-emitting diode is only made of the material FeCl ₃ was replaced by _CoCl2 .

In addition, this embodiment provides an optical transmittance testing device and a preparation method thereof. On the basis of Example 1, only the metal salt film in the optical transmittance testing device provided in Example 1 is used for the optical transmittance testing device. The layer material FeCl ₃ is replaced by CoCl ₂ .

Example 3

The embodiment of the present application provides a quantum dot light emitting diode and a preparation method thereof. The quantum dot light emitting diode is based on embodiment 1, only the material of the metal layer in the quantum dot light emitting diode provided in embodiment 1 is replaced with Pd.

In addition, this embodiment provides an optical transmittance testing device and a preparation method thereof. On the basis of Example 1, the optical transmittance testing device only uses the material of the metal layer in the optical transmittance testing device provided in Example 1 Ni is replaced by Pd.

Example 4

The embodiment of the present application provides a quantum dot light-emitting diode and a preparation method thereof. On the basis of embodiment 1, the quantum dot light-emitting diode is replaced by _FeCl3 , which is the material of the film layer of the metal salt in the quantum dot light-emitting diode provided in embodiment 1. is CoCl ₂ , and the material Ni of the metal layer is replaced with Pd.

In addition, this embodiment provides an optical transmittance testing device and a preparation method thereof. The optical transmittance testing device is based on Example 1, and the film layer of the metal salt in the optical transmittance testing device provided in Example 1 is The material FeCl ₃ is replaced by CoCl ₂ , and the material Ni of the metal layer is replaced by Pd.

Example 5

The embodiment of the present application provides a quantum dot light emitting diode and a preparation method thereof. The quantum dot light emitting diode is based on embodiment 1, only the material of the metal layer in the quantum dot light emitting diode provided in embodiment 1 is replaced with Pt.

In addition, this embodiment provides an optical transmittance testing device and a preparation method thereof. On the basis of Example 1, the optical transmittance testing device only uses the material of the metal layer in the optical transmittance testing device provided in Example 1 Ni is replaced by Pt.

Example 6

The embodiment of the present application provides a quantum dot light-emitting diode and a preparation method thereof. On the basis of embodiment 1, the quantum dot light-emitting diode is replaced by _FeCl3 , which is the material of the film layer of the metal salt in the quantum dot light-emitting diode provided in embodiment 1. is CoCl ₂ , and the material of the metal layer is replaced by Pt from Ni.

In addition, this embodiment provides an optical transmittance testing device and a preparation method thereof. The optical transmittance testing device is based on Example 1, and the film layer of the metal salt in the optical transmittance testing device provided in Example 1 is The material FeCl ₃ is replaced by CoCl ₂ , and the material Ni of the metal layer is replaced by Pt.

Example 7

Referring to FIG. 3 , the present embodiment provides a quantum dot light-emitting diode. The device structure of the quantum dot light-emitting diode includes a substrate 110, an anode 120, a hole injection layer 130, a hole transport layer 140, and a quantum dot light-emitting layer that are sequentially stacked. layer 150 , composite electron transport layer 160 , metal layer 170 and cathode 180 .

Referring to FIG. 4, this embodiment also provides a method for preparing the above-mentioned quantum dot light-emitting diode, including:

S121: providing a substrate 110, and preparing an IZO/Ag/IZO anode 120 on the substrate 110;

S122: Spin-coat m-MTDATA on the anode 120 to prepare a hole injection layer 130 with a thickness of 18 nm, and anneal the hole injection layer 130 in air at 185° C. for 17 minutes;

S123: In an argon atmosphere, spin-coat PVK on the hole injection layer 130 to prepare a hole transport layer 140 with a thickness of 17 nm, and anneal at 155° C. for 15 minutes;

S124: Spin-coat CdSe/ZnS on the hole transport layer 140 to prepare a quantum dot light-emitting layer 150 with a thickness of 50 nm, and anneal at 85° C. for 15 minutes;

S125: Spin-coat a mixture of LZO and FeCl ₃ on the quantum dot light-emitting layer 150 (the ratio of the amount of FeCl ₃ metal salt to LZO species in the mixture is 0.04) to form a composite electron transport layer 160 with a thickness of 63 nm, and ℃ annealing for 15 minutes;

S126: After the composite electron transport layer 160 is completely cured, evaporate Ni on the composite electron transport layer 160 to prepare a metal layer 170 with a thickness of 2 nm;

S127: evaporating Ag on the metal layer 170 to form a cathode 180 with a thickness of 75 nm;

S128: Encapsulation.

Example 8

Referring to FIG. 5 , this embodiment provides a quantum dot light emitting diode. The device structure of the quantum dot light emitting diode is an inverted structure, including: a substrate 110, a cathode 180, a metal layer 170, a composite electron transport layer 160, Quantum dot light emitting layer 150 , hole transport layer 140 , hole injection layer 130 and anode 120 . Wherein, the material of the composite electron transport layer 160 includes the electron transport material 161 and the metal salt 162 , and the electron transport material 161 penetrates into the metal salt 162 (shown in the form of a curve in FIG. 5 ).

Referring to FIG. 6, this embodiment also provides a method for preparing the above-mentioned quantum dot light-emitting diode, including:

S131: providing a substrate 110, and evaporating Al on the substrate to form a cathode 180 with a thickness of 75 nm;

S132: evaporating Pt on the cathode 180 to prepare a metal layer 170 with a thickness of 3 nm;

S133: After the metal layer 170 is completely cured, spin-coat FeCl ₃ on the metal layer 170 to prepare a film layer of the metal salt 162 with a thickness of 4 nm, and irradiate the device vertically with 254 nm UV for 20 minutes in a nitrogen environment;

S134: before the film layer of the metal salt 162 is completely cured, spin-coat AZO on the film layer of the metal salt 162 to prepare a film layer of the electron transport material 161 with a thickness of 60 nm, and anneal at 80° C. for 15 minutes;

S135: After the film layer of the electron transport material 161 is completely cured, spin-coat CdZnSe/ZnS on the film layer of the electron transport material 161 to prepare a quantum dot light-emitting layer 150 with a thickness of 50 nm, and anneal at 85° C. for 15 minutes;

S136: In a nitrogen atmosphere, spin-coat TFB on the quantum dot light-emitting layer 150 to prepare a hole transport layer 140 with a thickness of 17 nm, and anneal at 150° C. for 15 minutes;

S137: Spin-coat PEDOT:PSS on the hole transport layer 140 to prepare a hole injection layer 130 with a thickness of 22 nm, and anneal the hole injection layer 130 at 180° C. for 15 minutes in air;

S138: Prepare an anode 120 having an ITZO/Ag/ITZO structure on the hole injection layer 130;

S139: Encapsulation.

Comparative example 1 (standard device)

This comparative example provides a quantum dot light-emitting diode. The device structure of the quantum dot light-emitting diode is an upright structure, including: a substrate, an anode, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, An electron transport layer, and a cathode.

This comparative example also provides the preparation method of the above-mentioned quantum dot light-emitting diode, including:

S211: providing a substrate, and preparing an anode with an ITO/Ag/ITO structure on the substrate;

S212: Spin-coat PEDOT:PSS:s-MoO3 on the anode to prepare a hole injection layer with a thickness of 20 nm, and anneal the hole injection layer at 180° C. for 15 minutes in air;

S213: In a nitrogen atmosphere, spin-coat poly-TPD on the hole injection layer to prepare a hole transport layer with a thickness of 15 nm, and anneal at 150° C. for 15 minutes;

S214: Spin-coat CdSe/ZnS on the hole transport layer to prepare a quantum dot light-emitting layer with a thickness of 50 nm, and anneal at 85° C. for 15 minutes;

S215: Spin-coat LZO on the quantum dot light-emitting layer to prepare an electron transport layer with a thickness of 60 nm, and anneal at 80° C. for 15 minutes;

S216: evaporating Ag on the electron transport layer to form a cathode with a thickness of 80 nm;

S217: encapsulation.

In addition, this comparative example provides an optical transmittance testing device and a preparation method thereof. Wherein, the preparation method of the optical transmittance test device includes:

LZO was spin-coated on ITO to prepare an electron transport layer with a thickness of 60 nm and annealed at 80 °C for 15 min.

Comparative example 2 (device without metal layer)

This comparative example provides a quantum dot light-emitting diode. The device structure of the quantum dot light-emitting diode is an upright structure, including: a substrate, an anode, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, Composite electron transport layer, and cathode.

This comparative example also provides the preparation method of the above-mentioned quantum dot light-emitting diode, including:

S221: providing a substrate, and preparing an anode with an ITO/Ag/ITO structure on the substrate;

S222: Spin-coat PEDOT:PSS:s-MoO ₃ on the anode to prepare a hole injection layer with a thickness of 20 nm, and anneal the hole injection layer at 180° C. for 15 minutes in air;

S223: In a nitrogen atmosphere, spin-coat poly-TPD on the hole injection layer to prepare a hole transport layer with a thickness of 15 nm, and anneal at 150° C. for 15 minutes;

S224: Spin-coat CdSe/ZnS on the hole transport layer to prepare a quantum dot light-emitting layer with a thickness of 50 nm, and anneal at 85° C. for 15 minutes;

S225: Spin-coat LZO on the quantum dot light-emitting layer to prepare a film layer of an electron transport material with a thickness of 60 nm, and irradiate the obtained device vertically with 254 nm UV for 20 minutes in a nitrogen environment;

S226: Before the film layer of the above-mentioned electron transport material is completely cured, spin-coat FeCl3 on the film layer of the electron transport material to prepare a film layer of metal salt with a thickness of 3nm, and anneal at 80°C for 15 minutes to form a composite electron transport layer;

S227: Evaporating Ag on the composite electron transport layer to form a cathode with a thickness of 80 nm;

S228: encapsulation.

In addition, this comparative example provides an optical transmittance testing device and a preparation method thereof. Wherein, the preparation method of the optical transmittance test device includes:

Spin-coat LZO on ITO to prepare a film layer of electron transport material with a thickness of 60nm and irradiate the device vertically with 254nm UV for 20 minutes in a nitrogen environment. FeCl ₃ was spin-coated on the layer to prepare a metal salt film layer with a thickness of 3 nm and annealed at 80° C. for 15 minutes to form a composite electron transport layer.

Comparative example 3

This comparative example provides a quantum dot light-emitting diode and a preparation method thereof. On the basis of comparative example 2, the quantum dot light-emitting diode only uses the material _FeCl in the film layer of the metal salt in the quantum dot light-emitting diode provided in comparative example 2. Replaced by CoCl ₂ .

In addition, this comparative example provides an optical transmittance testing device and a preparation method thereof. On the basis of comparative example 2, the optical transmittance testing device only uses the film of the metal salt in the optical transmittance testing device provided in comparative example 2 The material FeCl ₃ in the layer was replaced by CoCl ₂ .

Comparative example 4 (does not contain metal salt)

This comparative example provides a quantum dot light-emitting diode. The device structure of the quantum dot light-emitting diode is an upright structure, including: a substrate, an anode, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, An electron transport layer, and a cathode.

This comparative example also provides the preparation method of the above-mentioned quantum dot light-emitting diode, including:

S231: providing a substrate, and preparing an anode with an ITO/Ag/ITO structure on the substrate;

S232: Spin-coat PEDOT:PSS:s-MoO ₃ on the anode to prepare a hole injection layer with a thickness of 20 nm, and anneal the hole injection layer at 180° C. for 15 minutes in air;

S233: In a nitrogen atmosphere, spin-coat poly-TPD on the hole injection layer to prepare a hole transport layer with a thickness of 15 nm, and anneal at 150° C. for 15 minutes;

S234: Spin-coat CdSe/ZnS on the hole transport layer to prepare a quantum dot light-emitting layer with a thickness of 50 nm, and anneal at 85° C. for 15 minutes;

S235: Spin-coat LZO on the quantum dot light-emitting layer to prepare an electron transport layer with a thickness of 60 nm, and anneal at 80° C. for 15 minutes;

S236: Evaporating Ni on the electron transport layer to prepare a metal layer with a thickness of 2 nm;

S237: Evaporating Ag on the electron transport layer to form a cathode with a thickness of 80 nm;

S238: Encapsulation.

In addition, this comparative example provides an optical transmittance testing device and a preparation method thereof. Wherein, the preparation method of the optical transmittance test device includes:

Spin-coat LZO on ITO to prepare an electron transport layer with a thickness of 60 nm and anneal at 80° C. for 15 minutes, and evaporate Ni on the above electron transport layer to prepare a metal layer with a thickness of 2 nm.

Comparative example 5

This comparative example provides a quantum dot light-emitting diode and a preparation method thereof. The quantum dot light-emitting diode is based on comparative example 4, only the material of the metal layer in the quantum dot light-emitting diode provided in comparative example 4 is replaced with Pd.

In addition, this comparative example provides an optical transmittance testing device and a preparation method thereof. On the basis of comparative example 4, the optical transmittance testing device only uses the material of the metal layer in the optical transmittance testing device provided in comparative example 4 Ni is replaced by Pd.

Comparative example 6

This comparative example provides a quantum dot light-emitting diode and its preparation method. On the basis of comparative example 4, the quantum dot light-emitting diode only replaces Ni with Pt as the material of the metal layer in the quantum dot light-emitting diode provided in comparative example 4.

In addition, this comparative example provides an optical transmittance testing device and a preparation method thereof. On the basis of comparative example 4, the optical transmittance testing device only uses the material of the metal layer in the optical transmittance testing device provided in comparative example 4 Ni is replaced by Pt.

Comparative Example 7 (excluding the non-high-temperature cross-linking operation on the film layer of the electron transport material)

This comparative example provides a quantum dot light-emitting diode. The device structure of the quantum dot light-emitting diode is an upright structure, including: a substrate, an anode, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, Composite electron transport layer, metal layer and cathode. Wherein, the materials of the composite electron transport layer include electron transport materials and metal salts.

This comparative example also provides the preparation method of the above-mentioned quantum dot light-emitting diode, including:

S241: providing a substrate, and preparing an anode with an ITO/Ag/ITO structure on the substrate;

S242: Spin-coat PEDOT:PSS:s-MoO ₃ on the anode to prepare a hole injection layer with a thickness of 20 nm, and anneal the hole injection layer at 180° C. for 15 minutes in air;

S243: In a nitrogen atmosphere, spin-coat poly-TPD on the hole injection layer to prepare a hole transport layer with a thickness of 15 nm, and anneal at 150° C. for 15 minutes;

S244: Spin-coat CdSe/ZnS on the hole transport layer to prepare a quantum dot light-emitting layer with a thickness of 50 nm, and anneal at 85° C. for 15 minutes;

S245: Spin-coat 60nm LZO on the quantum dot light-emitting layer to prepare a film layer of electron transport material;

S246: without curing the film layer of the above-mentioned electron transport material, directly spin-coat FeCl ₃ on the electron transport material to prepare a film layer of metal salt with a thickness of 3 nm, and anneal at 80° C. for 15 minutes;

S247: After the film layer of the metal salt is completely cured, evaporate Ni on the film layer of the deposited metal salt to prepare a metal layer with a thickness of 2 nm;

S248: evaporating Ag on the metal layer to form a cathode with a thickness of 80 nm;

S249: Encapsulation.

Carry out UV-VIS test to the optical transmittance test device in listed embodiment 1～6, comparative example 1～6, to measure the film transmittance of optical transmittance test device for the light of wavelength 380～720nm, the result See Table 1.

Table 1 UV-VIS film transmittance test data (test range 380~720nm)

Optical transmittance test device	Average transmittance (Avg)	Highest transmittance (Max)
Example 1	89.20%	93.3% @ 457nm
Example 2	84.80%	86.5% @ 466nm
Example 3	86.70%	90.1% @ 493nm
Example 4	81.10%	83.8% @ 519nm
Example 5	83.90%	86.2% @ 558nm
Example 6	80.20%	81.9% @ 544nm
Comparative example 1	76.90%	79.7% @ 434nm
Comparative example 2	91.50%	95.1% @ 440nm
Comparative example 3	87.60%	90.4% @ 447nm
Comparative example 4	71.40%	73.5% @ 720nm
Comparative example 5	65.80%	69.2% @ 720nm
Comparative example 6	60.90%	62.3% @ 720nm

As can be seen from the data in the table, compared with the existing optical transmittance test device provided by most such as comparative example 1, the optical transmittance test comprising the composite electron transport layer and the metal layer provided by embodiments 1 to 6 The average transmittance and maximum transmittance of the device increased.

In addition, the sheet resistance of the quantum dot light-emitting diodes in Example 2, Example 4, Example 6, Comparative Example 1, and Comparative Example 3 was tested, and the results showed that the sheet resistance of the quantum dot light-emitting diodes prepared in Comparative Example 1 was within 100Ω Left and right, the sheet resistance of the quantum dot light-emitting diode that includes the composite electron transport layer in Comparative Example 3 is 200~250Ω, while the sheet resistance of the quantum dot light-emitting diode that includes the composite electron transport layer and the metal layer in Examples 2, 4, and 6 is 50~60Ω. Therefore, the quantum dot light-emitting diode including the composite electron transport layer and the metal layer has lower sheet resistance and is more conducive to the transport of carriers.

The luminance L and external quantum efficiency EQE performance values of the quantum dot light-emitting diodes in the above-mentioned Examples 1-6 and Comparative Examples 1-6 were tested and calculated by using JVL (current-voltage-luminance) testing equipment, and the results are shown in Table 2.

Table 2 Device performance test data prepared in Examples 1-6 and Comparative Examples 1-6

quantum dot light emitting diode	EQE (%)	L (nit)
Example 1	12.1	7109
Example 2	12.6	6957
Example 3	12.9	6522
Example 4	13.1	6475
Example 5	14.1	6631
Example 6	14.9	6398
Comparative example 1	6.9	4882
Comparative example 2	6.4	5315
Comparative example 3	6.7	5209
Comparative example 4	11.4	3153
Comparative example 5	11.8	2892
Comparative example 6	14.3	2017

As can be seen from the data in Table 2, compared to most of the existing quantum dot light emitting diodes such as those provided in Comparative Example 1, the quantum dot light emitting diodes provided in Examples 1 to 6 (including composite electron transport materials that replace the electron transport layer) layers and metal layers) have increased external quantum efficiency and brightness. In addition, compared with the quantum dot light-emitting diodes provided in Comparative Example 1, the brightness of the quantum dot light-emitting diodes provided in Comparative Examples 2 and 3, which include a composite electron transport layer and no metal layer, is improved, but the external quantum efficiency does not change much. It shows that the quantum dot light-emitting diodes that only include the composite electron transport layer but not the metal layer have a poor effect on the improvement of the external quantum efficiency of the device. Compared with the quantum dot light-emitting diodes provided in Comparative Example 1, the external quantum efficiency of the quantum dot light-emitting diodes provided in Comparative Examples 4-6 that included a metal layer and did not have a composite electron transport layer that replaces the electron transport layer was significantly increased, but The decrease in brightness shows that the quantum dot light-emitting diode including only the metal layer but not the composite electron transport layer replacing the electron transport layer has a poor effect on improving the brightness of the device. However, the quantum dot light-emitting diodes provided by Examples 1-6 of the present application have better performance in terms of external quantum efficiency and brightness.

In summary, the composite electron transport layer and the metal layer in the light-emitting diode provided by the application complement each other and cooperate with each other, so that the light-emitting diode of the present application has higher transmittance, carrier transport, brightness, and efficiency than the prior art. Excellent performance, good overall effect.

A light-emitting diode provided by the embodiment of the present application and its preparation method have been introduced in detail above. In this paper, the principle and implementation of the present application have been explained by using specific examples. The description of the above embodiment is only used to help understand the present application. The method of application and its core idea; at the same time, for those skilled in the art, according to the idea of this application, there will be changes in the specific implementation and scope of application. In summary, the content of this specification should not be understood as Limitations on this Application.

Claims (20)

1. A light emitting diode, comprising:

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

   A composite electron transport layer, the composite electron transport layer is arranged between the cathode and the light-emitting layer, the material of the composite electron transport layer includes an electron transport material and a metal salt, and the metal element in the metal salt is selected from Group VIII elements; and

   A metal layer, the metal layer is arranged between the cathode and the composite electron transport layer, the material of the metal layer is a doped or undoped metal element, and the metal element in the metal element is selected from VIII family elements.
2. The light emitting diode according to claim 1, wherein, in the composite electron transport layer, the ratio of the amount of the metal salt to the electron transport material is 0.04˜0.1.
3. The light emitting diode according to claim 1, wherein the ratio of the amount of the simple metal to the electron transport material is 0.02-0.033.
4. The light-emitting diode according to claim 1, wherein the metal salt is selected from one or more of iron chloride, cobalt chloride, iron acetate, cobalt acetate, iron stearate, iron nitrate, and cobalt nitrate .
5. The light emitting diode according to claim 1, wherein the metal element is selected from one or more of nickel, palladium and platinum.
6. The light emitting diode according to claim 1, wherein the doping element in the doped metal element is selected from Group VIII elements, and the doping element is different from the metal element in the metal element.
7. The light emitting diode according to claim 1, wherein the electron transport material is selected from one or more of doped or undoped semiconductor nanoparticles and organic electron transport materials.
8. The light emitting diode according to claim 7, wherein the electron transport material is selected from doped or undoped TiO ₂ , ZnO, ZrO, SnO ₂ , WO ₃ , Ta ₂ O ₃ , HfO ₃ , Al ₂ One or more of O ₃ , ZrSiO ₄ , BaTiO ₃ , BaZrO ₃ , CdS, ZnSe, and ZnS.
9. The light emitting diode according to claim 7, wherein the doping element of the electron transport material is selected from one or more of Al, Mg, In, Li, Ga, Cd, Cs, Cu.
10. The light emitting diode according to claim 1, wherein the light emitting diode is one of a light emitting diode with an upright structure and a light emitting diode with an inverted structure.
11. The light emitting diode according to claim 1, wherein the light emitting diode is one of quantum dot light emitting diodes, organic light emitting diodes, and micron light emitting diodes.
12. The light emitting diode according to claim 11, wherein the quantum dot light emitting diode comprises a quantum dot light emitting layer, and the material of the quantum dot light emitting layer is selected from CdSe, CdS, ZnSe, ZnS, CdTe, ZnTe, CdZnS, CdZnSe , CdZnTe, ZnSeS, ZnSeTe, ZnTeS, CdSeS, CdSeTe, CdTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdSeSTe, ZnSeSTe, CdZnSeSTe, CdSe/ZnS, CdZnSe/ZnS, CdS/CdZnS, InP, InAs, InAsP, InP/InAs P, PbS One or more of , PbSe, PbTe, PbSeS, PbSeTe, PbSTe, PbSe/PbS.
13. A method of manufacturing a light emitting diode, comprising:

    provide the anode;

    forming a light-emitting layer on the anode;

    Depositing and forming a laminated composite electron transport layer and metal layer on the light-emitting layer;

    forming a cathode on the metal layer;

    Wherein, the material of the composite electron transport layer includes an electron transport material and a metal salt, and the metal elements in the metal salt are selected from group VIII elements;

    The material of the metal layer is a doped or undoped metal element, and the metal element in the metal element is selected from group VIII elements.
14. The method for preparing a light-emitting diode according to claim 13, wherein the step of depositing and forming a stacked composite electron transport layer and a metal layer comprises:

    The electron transport material is deposited on the light-emitting layer, and before the film layer of the electron transport material is cured, the metal salt is deposited on the film layer of the electron transport material, so that the electron transport deposited with the metal salt is obtained. The material film layer is cured to form a composite electron transport layer;

    Depositing the simple metal substance on the composite electron transport layer forms a metal layer.
15. The method for preparing a light-emitting diode according to claim 14, wherein said curing to form a composite electron transport layer is realized by exposing the electron transport material film layer deposited with the metal salt to the air, and said exposed to the air The method includes placing the film layer of the electron transport material deposited with the metal salt in the air environment for 0.25-1 min.
16. The method for preparing a light-emitting diode according to claim 14, wherein the formation of the composite electron transport layer by curing is realized by ultraviolet light irradiation, and the ultraviolet light irradiation method includes irradiating the metal salt-deposited layer with ultraviolet light. Electron transport material film layer 0.25~30min.
17. A method of manufacturing a light emitting diode, comprising:

    provide the cathode;

    Depositing a laminated metal layer and composite electron transport layer on the cathode;

    forming a light emitting layer on the composite electron transport layer;

    forming an anode on the light-emitting layer;

    Wherein, the material of the composite electron transport layer includes an electron transport material and a metal salt, and the metal elements in the metal salt are selected from group VIII elements;

    The material of the metal layer is a doped or undoped metal element, and the metal element in the metal element is selected from group VIII elements.
18. The method for preparing a light emitting diode according to claim 17, wherein the step of depositing and forming a laminated metal layer and a composite electron transport layer comprises:

    Depositing the metal element on the cathode to form a metal layer;

    Depositing the metal salt on the metal layer, and depositing the electron transport material on the film layer of the metal salt before the film layer of the metal salt is solidified, to obtain a metal salt film deposited with the electron transport material layer, cured to form a composite electron transport layer.
19. The method for preparing a light-emitting diode according to claim 18, wherein said curing to form a composite electron transport layer is realized by exposing the metal salt film layer deposited with electron transport materials to the air, and said exposed to the air The method includes placing the metal salt film layer deposited with the electron transport material in an air environment for 0.25-1 min.
20. The method for preparing a light-emitting diode according to claim 18, wherein said curing to form a composite electron transport layer is realized by means of ultraviolet light irradiation, and said means of ultraviolet light irradiation includes using ultraviolet light to irradiate said deposited electron transport material The metal salt film layer is 0.25~30min.