Light emitting diode and method of manufacturing the same

Abstract

The embodiment of the application discloses a light emitting diode and a preparation method thereof, and relates to the field of optoelectronic technology. The light emitting diode comprises an anode, a cathode, a light emitting layer arranged between the anode and the cathode, a composite electron transport layer arranged between the cathode and the light emitting layer, and a metal layer arranged between the cathode and the composite electron transport layer. The material of the composite electron transport layer comprises a first material and a second material. The first material is a first electron transport material, and the second material is a metal salt. The metal element in the metal salt is 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. The composite electron transport layer of the light emitting diode has good transmittance, and the light emitting diode has high brightness and efficiency.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic technology, specifically to a light-emitting diode and its fabrication method. Background Technology

[0002] As a novel display and lighting technology, light-emitting diode (LED) technology possesses excellent energy efficiency, reliability, safety, and environmental friendliness, thus enjoying broad development prospects and remaining one of the important research directions in display and lighting.

[0003] Currently, the main structure of a light-emitting diode (LED) includes a cathode, anode, hole transport layer, electron transport layer, and emissive layer. However, this structure has not yet achieved ideal values ​​in terms of brightness, efficiency, and lifespan. Because the transmittance of each film layer material (such as the electron transport layer) is relatively low, light emitted from the emissive layer suffers non-dissipative loss in its emission direction due to light absorption by the thin film, resulting in a decrease in the LED's brightness and efficiency. Summary of the Invention

[0004] This application provides a light-emitting diode (LED) with high efficiency.

[0005] This application also provides a method for fabricating a light-emitting diode.

[0006] This application provides a light-emitting diode, including:

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

[0008] A composite electron transport layer is disposed between the cathode and the light-emitting layer. The composite electron transport layer is made of a first material and a second material; wherein the first material is a first electron transport material; and the second material is a metal salt, wherein the metal element in the metal salt is selected from group VIII elements; and

[0009] A metal layer is disposed between the cathode and the composite electron transport layer. The material of the metal layer is a doped or undoped elemental metal, and the metal element in the elemental metal is selected from group VIII elements.

[0010] Optionally, in some embodiments of this application, the molar ratio of the second material to the first material in the composite electron transport layer is 0.04 to 0.1; and / or

[0011] The molar ratio of the metallic element to the first material is 0.02 to 0.033.

[0012] Optionally, in some embodiments of this 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.

[0013] Optionally, in some embodiments of this application, the metallic element is selected from one or more of nickel, palladium, and platinum; and / or

[0014] The doping elements of metallic elements are selected from group VIII elements, and the doping elements are different from the metallic elements in the metallic element.

[0015] Optionally, in some embodiments of this application, the first electron transport material is selected from one or more of doped or undoped metal oxides, doped or undoped semiconductor nanoparticles, and organic electron transport materials; and / or

[0016] The first electron transport material is selected from one or more of the following: doped or undoped TiO2, ZnO, ZrO, SnO2, WO3, Ta2O3, HfO3, Al2O3, ZrSiO4, BaTiO3, BaZrO3, CdS, ZnSe, and ZnS; the doping element is selected from one or more of the following: Al, Mg, In, Li, Ga, Cd, Cs, and Cu.

[0017] Optionally, in some embodiments of this application, the light-emitting diode is a normally positioned or inverted light-emitting diode; and / or

[0018] A light-emitting diode (LED) is one of three types: quantum dot LED, organic LED, or micron LED.

[0019] Optionally, in some embodiments of this 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 one or more of CdSe, CdS, ZnSe, ZnS, CdTe, ZnTe, CdZnS, CdZnSe, CdZnTe, ZnSeS, ZnSeTe, ZnTeS, CdSeS, CdSeTe, CdTeS, CdZnSeS, CdZnSeTe, CdZnSeTe, CdZnSTe, CdSeSTe, ZnSeSTe, CdZnSeSTe, CdSe / ZnS, CdZnSe / ZnS, CdS / CdZnS, InP, InAs, InAsP, InP / InAsP, PbS, PbSe, PbTe, PbSeS, PbSeTe, PbSTe, and PbSe / PbS.

[0020] In addition, a method for fabricating a light-emitting diode includes:

[0021] An anode is provided, a light-emitting layer is formed on the anode, a stacked composite electron transport layer and a metal layer are deposited on the light-emitting layer, and a cathode is formed on the metal layer; or

[0022] A cathode is provided, and a stacked metal layer and a composite electron transport layer are deposited on the cathode. A light-emitting layer is formed on the composite electron transport layer, and an anode is formed on the light-emitting layer.

[0023] The composite electron transport layer comprises a first material and a second material; the first material is a first electron transport material; the second material is a metal salt, wherein the metal element in the metal salt is selected from group VIII elements.

[0024] The material of the metal layer is a doped or undoped elemental metal, and the metal element in the elemental metal is selected from group VIII elements.

[0025] Optionally, in some embodiments of this application, the step of depositing the above-described composite electron transport layer and metal layer includes:

[0026] A first electron transport material is deposited on the light-emitting layer, and a metal salt is deposited on the first electron transport material before the film layer of the first electron transport material is cured, and then cured to form a composite electron transport layer.

[0027] Depositing a metallic element onto a composite electron transport layer to form a metallic layer; or

[0028] The steps described above for depositing and forming a stacked metal layer and a composite electron transport layer include:

[0029] A metallic layer is formed by depositing elemental metal on the cathode.

[0030] A metal salt is deposited on a metal layer, and a first electron transport material is deposited on the metal salt film before the metal salt film is cured, and then cured to form a composite electron transport layer.

[0031] Optionally, in some embodiments of this application, the above-described curing to form the composite electron transport layer is achieved by exposing the first electron transport material to air and / or by ultraviolet light irradiation;

[0032] Exposure to air includes placing the first electron transport material in an air environment for 0.25 to 1 minute;

[0033] The ultraviolet irradiation method includes irradiating the first electron transport material with ultraviolet light for 0.25 to 30 minutes.

[0034] Compared to existing technologies, the light-emitting diode (LED) provided by this invention comprises a metal salt of a group VIII metal and a first electron transport material. The resulting composite electron transport layer has high film transmittance and fewer defects, effectively reducing the probability of emitted light being absorbed by defects, thereby enhancing the device transmittance of the LED. Furthermore, the LED of this invention includes a metal layer comprising group VIII elements stacked with the aforementioned composite electron transport layer. This metal layer has high conductivity, effectively balancing the increased film resistance caused by the introduction of the group VIII metal salt, which is beneficial for carrier transport and improves device efficiency. The composite electron transport layer and the metal layer in the LED of this invention complement each other, resulting in high brightness and efficiency for the LED. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of the structure of the quantum dot light-emitting diode provided in Embodiment 1 of the present invention;

[0037] Figure 2 This is a schematic diagram of the structure of the quantum dot light-emitting diode provided in Embodiment 7 of the present invention.

[0038] The following are explanations of the reference numerals in the attached figures:

[0039] Substrate 110; Anode 120; Hole injection layer 130; Hole transport layer 140; Quantum dot light-emitting layer 150; Composite electron transport layer 160; First electron transport material 161; Metal salt 162; Metal layer 170; Cathode 180. Detailed Implementation

[0040] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0041] This application provides a light-emitting diode and a method for fabricating the same. Detailed descriptions are provided below. It should be noted that the order of description of the following embodiments is not intended to limit the preferred order of the embodiments. Furthermore, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc., are used merely as illustrative and do not impose numerical requirements or establish an order. Various embodiments of the present invention may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a rigid limitation on the scope of the present invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single values ​​within that range. For example, it should be considered that the range description from 0.04 to 0.1 has 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., and single numbers within the range, such as 0.04, 0.05, and 0.06, regardless of the range. Additionally, whenever a numerical range is specified in this document, it means that any referenced number (fraction or integer) within the range is included.

[0042] This application provides a light-emitting diode, including:

[0043] Anode, cathode, and light-emitting layer disposed between the anode and cathode;

[0044] A composite electron transport layer is disposed between the cathode and the light-emitting layer. The composite electron transport layer is made of a first material and a second material; wherein the first material is a first electron transport material; and the second material is a metal salt, wherein the metal element in the metal salt is selected from group VIII elements; and

[0045] A metal layer is disposed between the cathode and the composite electron transport layer. The material of the metal layer is a doped or undoped elemental metal, and the metal element in the elemental metal is selected from group VIII elements.

[0046] The composite electron transport layer containing metal salts in this invention has high transmittance, thereby enabling the light-emitting diode (LED) to have high brightness. Simultaneously, the metal layer stacked with the composite electron transport layer effectively balances the thin-film resistance, improving the efficiency of the LED. The stacking configuration of the composite electron transport layer and the light-emitting layer is a generalized configuration; that is, the composite electron transport layer can be in direct contact with the light-emitting layer and stacked thereon, or it can be stacked with other film layers between the composite electron transport layer and the light-emitting layer.

[0047] Furthermore, in this invention, the metal element in the metal layer and the metal element in the metal salt are elements of the same group (Group VIII), so that the metal atoms in the metal layer and the metal atoms in the metal salt can have similar electronic orbitals.

[0048] In some embodiments, in the composite electron transport layer, the molar ratio of the second material to the first material is 0.04 to 0.1; and / or

[0049] The molar ratio of the metallic element to the first material is 0.02 to 0.033.

[0050] When the ratio of the amount of the second material to the first material is within the above-mentioned range, it is possible to effectively improve the transmittance of the composite electron transport layer without excessively increasing the thin film resistance of the composite electron transport layer. Furthermore, the range of the ratio of the amount of the second material to the first material can also be a sub-range of the above-mentioned range. For example, in some embodiments, the ratio of the amount of the second material to the first material can be 0.05 to 0.1, or 0.04 to 0.067.

[0051] When the molar ratio of the metallic element to the first material is within the aforementioned range, the thin-film resistance of the composite electron transport layer can be effectively reduced without significantly decreasing the transmittance of the composite electron transport layer. In some embodiments, the molar ratio can be approximated by the film thickness ratio.

[0052] 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 ferric acetate can be ferric acetate monohydrate, and the cobalt acetate can be cobalt acetate tetrahydrate.

[0053] In some embodiments, the metallic element may be selected from one or more of nickel, palladium, and platinum. The doping element of the metallic element is selected from group VIII elements, and the doping element is different from the metallic element in the metallic element.

[0054] In some embodiments, the first electron transport material is selected from one or more of doped or undoped metal oxides, doped or undoped semiconductor nanoparticles, and organic electron transport materials.

[0055] Furthermore, the first electron transport material may be selected from one or more of doped or undoped TiO2, ZnO, ZrO, SnO2, WO3, Ta2O3, HfO3, Al2O3, ZrSiO4, BaTiO3, BaZrO3, CdS, ZnSe, and ZnS; the doping element may be selected from one or more of Al, Mg, In, Li, Ga, Cd, Cs, and Cu.

[0056] In some embodiments, the light-emitting diode is a light-emitting diode with an upright structure or an inverted structure.

[0057] In some embodiments, the light-emitting diode (LED) is one of a quantum dot LED (QLED), an organic light-emitting diode (OLED), or a microLED. Further, the LED in this invention can be a quantum dot LED with an upright or inverted structure, an organic light-emitting diode with an upright or inverted structure, or a microLED with an upright or inverted structure. Preferably, the LED is an upright LED. Further, the device structure of the LED in this invention can be one of a three-layer device, a multilayer device, a top-emitter device, a bottom-emitter device, or a double-sided emitting device.

[0058] 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 one or more of 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, PbSTe, and PbSe / PbS. In the above descriptions of CdSe / ZnS, the " / " indicates that the material following the " / " (as a shell) covers the material preceding the " / " (as a core). Preferably, the material of the quantum dot luminescent layer is selected from one or more of the following: group II-VI semiconductor nanocrystals CdSe, CdS, ZnSe, CdS, PbS, PbS, and core-shell structure materials composed of the above-mentioned group II-VI semiconductor nanocrystals.

[0059] This application also provides a method for fabricating a light-emitting diode (LED). When fabricating a positively positioned LED, the above-mentioned fabrication method includes:

[0060] An anode is provided, a light-emitting layer is formed on the anode, a stacked composite electron transport layer and a metal layer are deposited on the light-emitting layer, and a cathode is formed on the metal layer;

[0061] The composite electron transport layer comprises a first material and a second material; the first material is a first electron transport material; the second material is a metal salt, wherein the metal element in the metal salt is selected from group VIII elements.

[0062] The material of the metal layer is a doped or undoped elemental metal, and the metal element in the elemental metal is selected from group VIII elements.

[0063] When fabricating an inverted light-emitting diode, the above-mentioned fabrication method includes:

[0064] A cathode is provided, and a stacked metal layer and a composite electron transport layer are deposited on the cathode. A light-emitting layer is formed on the composite electron transport layer, and an anode is formed on the light-emitting layer.

[0065] The composite electron transport layer comprises a first material and a second material; the first material is a first electron transport material; the second material is a metal salt, wherein the metal element in the metal salt is selected from group VIII elements.

[0066] The material of the metal layer is a doped or undoped elemental metal, and the metal element in the elemental metal is selected from group VIII elements.

[0067] In the above description of depositing another film layer on the film layer (e.g., "forming a stacked composite electron transport layer and a metal layer on the light-emitting layer"), "on" is used in a broad sense, meaning above or above. That is, another film layer can be deposited directly on the film layer, or other film layers can be formed on the film layer, and then another film layer can be formed on those other film layers. Further, when depositing the composite electron transport layer using the above-described method for fabricating a light-emitting diode, the first electron transport material and the metal salt can be mixed and directly deposited to form the composite electron transport layer, or the first electron transport material and the metal salt can be deposited separately to form the composite electron transport layer. Preferably, the composite electron transport layer is formed by depositing the first electron transport material and the metal salt separately.

[0068] When forming a composite electron transport layer by separately depositing the first electron transport material and the metal salt, the deposition method varies slightly depending on the structure of the light-emitting diode (LED) device. For example, when the LED device structure is a positive-position structure,

[0069] The steps described above for depositing and forming a stacked composite electron transport layer and a metal layer include:

[0070] A first electron transport material is deposited on the light-emitting layer, and a metal salt is deposited on the first electron transport material before the film layer of the first electron transport material is cured, and then cured to form a composite electron transport layer.

[0071] A metal layer is formed by depositing a metallic element on the composite electron transport layer. When the light-emitting diode (LED) device structure is an inverted structure, the steps of depositing the stacked metal layer and the composite electron transport layer include:

[0072] A metallic layer is formed by depositing elemental metal on the cathode.

[0073] A metal salt is deposited on a metal layer, and a first electron transport material is deposited on the metal salt film before the metal salt film is cured, and then cured to form a composite electron transport layer.

[0074] However, regardless of whether a light-emitting diode with a positive or negative structure is being fabricated, regarding the deposition of the first electron transport material and the metal salt, the material to be deposited later should be deposited on top of the material before the material is completely cured and forms a separate film. In this way, the material to be deposited later can penetrate into the thin film of the material to be deposited earlier, thereby introducing group VIII metal elements during the crystallization stage of the first electron transport material to form a composite electron transport layer, reducing the probability of emitted light being absorbed by defects, and improving transmittance.

[0075] When a composite electron transport layer is formed by separately depositing a first electron transport material and a metal salt, the deposited first electron transport material layer and the metal salt layer are not completely independent layers. At the interface between the two layers, the lower layer contains material from the upper layer that has permeated into it. The group VIII metal salt deposited between the first electron transport material layer and the elemental metal layer effectively separates the metal layer from the independent first electron transport material layer, providing a protective barrier. This makes the lattice gaps between the materials at the layer interface closer, resulting in fewer defects at the interface. Consequently, most light can pass through the layer interface without being absorbed, improving the final brightness of the device.

[0076] In some embodiments, to ensure that the material deposited earlier has not fully cured when the material deposited later is deposited, a non-high-temperature crosslinking operation can be used to cure and crosslink the material deposited earlier. For example, in the fabrication of a positive-position light-emitting diode, the above-mentioned curing to form a composite electron transport layer can be achieved by exposing the first electron transport material to air and / or by ultraviolet light irradiation;

[0077] Exposure to air includes placing the first electron transport material in an air environment for 0.25 to 1 minute;

[0078] The ultraviolet irradiation method includes irradiating the first electron transport material with ultraviolet light for 0.25 to 30 minutes.

[0079] When fabricating an inverted light-emitting diode, the aforementioned curing to form a composite electron transport layer can be achieved by exposing the metal salt to air and / or by irradiating it with ultraviolet light.

[0080] Exposure to air can be achieved by placing the metal salt in the air for 0.25 to 1 minute.

[0081] Ultraviolet light irradiation methods include irradiating metal salts with ultraviolet light for 0.25 to 30 minutes.

[0082] The above-mentioned ultraviolet irradiation method can be carried out in a protective gas atmosphere (such as nitrogen or inert gas); the ultraviolet light source can vertically irradiate the thin film of the device; the wavelength of the ultraviolet light can be 240-260 nm, preferably, the wavelength of the ultraviolet light is 254 nm.

[0083] Furthermore, the first electron transport material film can be cured by simply exposing it to air, by simply irradiating it with ultraviolet light, or by exposing it to air and irradiating it with ultraviolet light simultaneously. However, when curing the first electron transport material film by simultaneously exposing it to air and irradiating it with ultraviolet light, the exposure time should be appropriately shortened. For example, when curing the first electron transport material film by simultaneously exposing it to air and irradiating it with ultraviolet light, the exposure time can be 0.25–0.5 min; while when curing the first electron transport material film by simply exposing it to air, the exposure time can be 0.5–1 min; and when curing the first electron transport material film by simply irradiating it with ultraviolet light, the ultraviolet light irradiation time can be 20–30 min. Furthermore, 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 can be fabricated using the above-described method for fabricating a light-emitting diode.

[0084] When fabricating a quantum dot light-emitting diode (LED) with a structure of anode / hole injection layer / hole transport layer / quantum dot emitting layer / electron transport layer / cathode, the fabrication method of the LED may include:

[0085] A hole injection layer is deposited on a substrate with an anode.

[0086] Deposit a hole transport layer on the hole injection layer;

[0087] Deposit a quantum dot luminescent layer on the hole transport layer;

[0088] Deposit the first electron transport material on the quantum dot luminescent layer;

[0089] A metal salt is deposited before the first electron transport material film is cured to form a composite electron transport layer;

[0090] After the deposited metal salt film has solidified, a metal layer is deposited on the metal salt film.

[0091] A cathode is fabricated on the aforementioned metal layer; and

[0092] Encapsulation.

[0093] The anode material can be selected from doped or undoped metal oxides, such as ITO, IZO, ITZO, ICO, SnO2, In2O3, Cd:ZnO, F:SnO2, In:SnO2, Ga:SnO2, AZO, etc.; it can also be selected from metallic materials, such as Ni, Pt, Au, Ag, Cu, Al, Ir; or it can be a metallic material containing CNTs, etc. The colon ":" in the above descriptions of Cd:ZnO, etc., indicates doping. Preferably, the anode is an anode with an ITO / metal / ITO structure, wherein the ITO is preferably indium-doped ITO, and the metal can be selected from one or more of Au, Ag, Al, and Cu.

[0094] The hole injection layer material can be selected from the above-mentioned hole injection layer materials, including but not limited to 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'-tetra(4-methoxyphenyl)-benzidine (TPD), 4-bis[N-(1-naphthyl)-N-phenyl-amino]biphenyl (α-NPD), 4,4',4”-tris[phenyl(m-tolyl)amino]tris[...]. The material is selected from one or more of the following: phenylamine (m-MTDATA), 4,4',4”-tris(N-carbazolyl)-triphenylamine (TCTA), 1,1-bis[(di-4-tolylamino)phenylcyclohexane (TAPC), 4,4',4”-tris(diphenylamino)triphenylamine (TDATA) doped with tetrafluoro-tetracyanoquinone dimethylane (F4-TCNQ), 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-NPD), and hexaazabenzanphenanthrene-hexanonitrile (HAT-CN). Preferably, the material of the hole layer can be selected from PEDOT:PSS or PEDOT:PSS:s-MoO3.

[0095] The material for the hole transport layer can be selected from 4,4'-N,N'-dicarbazolyl-biphenyl (CBP), N,N'-diphenyl-N,N'-bis(1-naphthyl)-1,1'-biphenyl-4,4”-diamine (α-NPD), polyN,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-T) PD), 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 vinylidene and its derivatives such as poly(phenylene vinylidene) (PPV), poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylene vinylidene] (MEH-PPV), poly[2-methoxy-5-(3',7'-dimethyloctyloxy)-1,4-phenylene vinylidene] (MOMO-PPV), copper phthalocyanine (CuPc), aromatic tertiary amines or polynuclear aromatics Tertiary amines, 4,4'-bis(p-carbazolyl)-1,1'-biphenyl compounds, N,N,N',N'-tetraarylbenzidine (TPB), PEDOT:PSS and its derivatives, poly(N-vinylcarbazole) (PVK) and its derivatives, polymethyl methacrylate (PMMA) and its derivatives, poly(9,9-octylfluorene) (PFO) and its derivatives, poly(spirofluorene) and its derivatives, and N,N'-di(naphthyl-1-yl)-N,N'-diphenylbenzidine (NPB). Preferably, the hole transport layer can be selected from one or more of TFB, PVK, Poly-TPD, and NPB.

[0096] The cathode material can be selected from one or more of Ca, Ba, Ca:Al, LiF:Ca, LiF:Al, BaF2:Al, CsF:Al, CaCO3:Al, BaF2:Ca:Al, Al, Mg, Au:Mg, and Ag:Mg. Preferably, the cathode material can be selected from Al and / or Ag.

[0097] Example 1

[0098] See Figure 1This embodiment provides a quantum dot light-emitting diode (LED). The device structure of this quantum dot LED is a positive-position structure, comprising: a substrate 110, an anode 120, a hole injection layer 130, a hole transport layer 140, a quantum dot light-emitting layer 150, a composite electron transport layer 160, a metal layer 170, and a cathode 180, sequentially stacked. The composite electron transport layer 160 is made of a first electron transport material 161 and a metal salt 162. The first electron transport material 161 is infiltrated with (… Figure 1 (Represented in the form of a curve) contains metal salt 162.

[0099] This embodiment also provides a method for fabricating the above-mentioned quantum dot light-emitting diode, including:

[0100] S11: Provide a substrate 110, and fabricate an anode 120 having an ITO / Ag / ITO structure on the substrate 110;

[0101] S12: PEDOT:PSS:s-MoO3 is spin-coated onto anode 120 to prepare hole injection layer 130 with a thickness of 20nm. Hole injection layer 130 is annealed in air at 180°C for 15 minutes.

[0102] S13: In a nitrogen atmosphere, poly-TPD is spin-coated onto the hole injection layer 130 to prepare a hole transport layer 140 with a thickness of 15 nm and then annealed at 150 °C for 15 minutes.

[0103] S14: Spin-coat CdSe / ZnS onto hole transport layer 140 to prepare quantum dot light-emitting layer 150 with a thickness of 50 nm and anneal at 85 °C for 15 minutes;

[0104] S15: Spin-coat LZO onto the quantum dot light-emitting layer 150 to prepare a film layer of the first electron transport material 161 with a thickness of 60 nm. The obtained device is then subjected to vertical irradiation with 254 nm UV in a nitrogen atmosphere for 20 minutes.

[0105] S16: Before the film layer of the first electron transport material 161 is completely cured, FeCl3 is spin-coated on the film layer of the first electron transport material 161 to prepare a film layer of metal salt 162 with a thickness of 3 nm, and then annealed at 80°C for 15 minutes.

[0106] S17: After the metal salt 162 film is completely cured, Ni is deposited on the metal salt 162 film to prepare a metal layer 170 with a thickness of 2 nm.

[0107] S18: Ag is vapor-deposited on metal layer 170 to form cathode 180 with a thickness of 80 nm;

[0108] S19: Package.

[0109] Furthermore, this embodiment provides an optical transmittance testing device and its fabrication method. The fabrication method of the optical transmittance testing device includes:

[0110] LZO was spin-coated onto ITO to prepare a first electron transport material 161 film with a thickness of 60 nm. The device was then vertically irradiated with 254 nm UV in a nitrogen environment for 20 minutes. Before the first electron transport material 161 film was completely cured, FeCl3 was spin-coated onto the first electron transport material 161 film to prepare a metal salt 162 film with a thickness of 3 nm. The metal salt 162 film was then annealed at 80 °C for 15 minutes. After the metal salt 162 film was completely cured and a composite electron transport layer 160 was formed together with the first electron transport material 161 film, Ni was vapor-deposited onto the metal salt 162 film to prepare a metal layer with a thickness of 2 nm.

[0111] Example 2

[0112] This application provides a quantum dot light-emitting diode and its fabrication method. The quantum dot light-emitting diode is based on Example 1, except that the material FeCl3 of the metal salt film layer in the quantum dot light-emitting diode provided in Example 1 is replaced with CoCl2.

[0113] In addition, this embodiment provides an optical transmittance testing device and its preparation method. The optical transmittance testing device is based on the optical transmittance testing device of embodiment 1, except that the material FeCl3 of the metal salt film layer in the optical transmittance testing device of embodiment 1 is replaced with CoCl2.

[0114] Example 3

[0115] This application provides a quantum dot light-emitting diode and its fabrication method. The quantum dot light-emitting diode is based on Example 1, except that the material Ni of the metal layer in the quantum dot light-emitting diode provided in Example 1 is replaced with Pd.

[0116] In addition, this embodiment provides an optical transmittance testing device and its preparation method. The optical transmittance testing device is based on Embodiment 1, except that the material Ni of the metal layer in the optical transmittance testing device provided in Embodiment 1 is replaced with Pd.

[0117] Example 4

[0118] This application provides a quantum dot light-emitting diode and its fabrication method. Based on Example 1, the material FeCl3 of the metal salt film layer in the quantum dot light-emitting diode provided in Example 1 is replaced with CoCl2, and the material Ni of the metal layer is replaced with Pd.

[0119] In addition, this embodiment provides an optical transmittance testing device and its preparation method. Based on the optical transmittance testing device of embodiment 1, the material FeCl3 of the metal salt film layer in the optical transmittance testing device of embodiment 1 is replaced with CoCl2, and the material Ni of the metal layer is replaced with Pd.

[0120] Example 5

[0121] This application provides a quantum dot light-emitting diode and its fabrication method. The quantum dot light-emitting diode is based on Example 1, except that the material Ni of the metal layer in the quantum dot light-emitting diode provided in Example 1 is replaced with Pt.

[0122] In addition, this embodiment provides an optical transmittance testing device and its preparation method. The optical transmittance testing device is based on Embodiment 1, except that the material Ni of the metal layer in the optical transmittance testing device provided in Embodiment 1 is replaced with Pt.

[0123] Example 6

[0124] This application provides a quantum dot light-emitting diode and its fabrication method. Based on Example 1, the material FeCl3 of the metal salt film layer in the quantum dot light-emitting diode provided in Example 1 is replaced with CoCl2, and the material Ni of the metal layer is replaced with Pt.

[0125] In addition, this embodiment provides an optical transmittance testing device and its preparation method. Based on the optical transmittance testing device of embodiment 1, the material FeCl3 of the metal salt film layer in the optical transmittance testing device of embodiment 1 is replaced with CoCl2, and the material Ni of the metal layer is replaced with Pt.

[0126] Example 7

[0127] See Figure 2 This embodiment provides a quantum 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, a quantum dot light-emitting layer 150, a composite electron transport layer 160, a metal layer 170, and a cathode 180, which are stacked sequentially.

[0128] This embodiment also provides a method for fabricating the above-mentioned quantum dot light-emitting diode, including:

[0129] S11: Provide a substrate 110, and fabricate an IZO / Ag / IZO anode 120 on the substrate 110;

[0130] S12: m-MTDATA is spin-coated onto anode 120 to prepare hole injection layer 130 with a thickness of 18 nm. Hole injection layer 130 is annealed in air at 185 °C for 17 minutes.

[0131] S13: In an argon atmosphere, spin-coat PVK onto 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.

[0132] S14: Spin-coat CdSe / ZnS onto hole transport layer 140 to prepare quantum dot light-emitting layer 150 with a thickness of 50 nm and anneal at 85 °C for 15 minutes;

[0133] S15: A mixture of LZO and FeCl3 (the molar ratio of FeCl3 metal salt to LZO in the mixture is 0.04) is spin-coated onto the quantum dot light-emitting layer 150 to form a composite electron transport layer 160 with a thickness of 63 nm, and then annealed at 80 °C for 15 minutes.

[0134] S17: After the composite electron transport layer 160 is completely cured, Ni is deposited on the composite electron transport layer 160 to prepare a metal layer 170 with a thickness of 2nm.

[0135] S18: Ag is vapor-deposited on metal layer 170 to form cathode 180 with a thickness of 75 nm;

[0136] S19: Package.

[0137] Example 8

[0138] This embodiment provides a quantum light-emitting diode (LED). The device structure of the quantum dot LED is an inverted structure, including: a substrate, a cathode, a metal layer, a composite electron transport layer, a quantum dot light-emitting layer, a hole transport layer, a hole injection layer, and an anode, which are stacked sequentially.

[0139] This embodiment also provides a method for fabricating the above-mentioned quantum dot light-emitting diode, including:

[0140] S11: Provide a substrate and deposit Al on the substrate to form a cathode with a thickness of 75 nm;

[0141] S12: Pt is deposited on the cathode to prepare a metal layer with a thickness of 3 nm;

[0142] S13: After the above metal layer is completely cured, FeCl3 is spin-coated on the metal layer to prepare a metal salt film with a thickness of 4 nm and the device is vertically irradiated with 254 nm UV in a nitrogen environment for 20 minutes.

[0143] S14: Before the above metal salt film is completely cured, spin-coat AZO onto the metal salt film to prepare a first electron transport material film with a thickness of 60 nm and anneal at 80 °C for 15 minutes.

[0144] S15: After the first electron transport material film layer is completely cured, CdZnSe / ZnS is spin-coated on the first electron transport material film layer to prepare a quantum dot light-emitting layer with a thickness of 50nm and annealed at 85°C for 15 minutes.

[0145] S16: In a nitrogen atmosphere, spin-coat TFB onto the quantum dot light-emitting layer to prepare a hole transport layer with a thickness of 17 nm and anneal at 150 °C for 15 minutes.

[0146] S17: Spin-coat PEDOT:PSS onto the hole transport layer to prepare a hole injection layer with a thickness of 22nm, and anneal the hole injection layer in air at 180°C for 15 minutes.

[0147] S18: An anode with an ITZO / Ag / ITZO structure is prepared on the hole injection layer;

[0148] S19: Package.

[0149] Comparative Example 1 (Standard Device)

[0150] This comparative example provides a quantum light-emitting diode (LED). The device structure of the quantum dot LED is a positive 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, which are stacked sequentially.

[0151] This comparative example also provides a method for fabricating the aforementioned quantum dot light-emitting diode, including:

[0152] S11: Provide a substrate and fabricate an anode with an ITO / Ag / ITO structure on the substrate;

[0153] S12: PEDOT:PSS:s-MoO3 was spin-coated onto the anode to prepare a hole injection layer with a thickness of 20 nm. The hole injection layer was then annealed in air at 180 °C for 15 minutes.

[0154] S13: In a nitrogen atmosphere, poly-TPD was spin-coated onto the hole injection layer to prepare a hole transport layer with a thickness of 15 nm and then annealed at 150 °C for 15 minutes.

[0155] S14: Spin-coat CdSe / ZnS onto 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;

[0156] S15: Spin-coat LZO onto 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;

[0157] S16: Ag is deposited on the electron transport layer to form a cathode with a thickness of 80 nm;

[0158] S17: Package.

[0159] In addition, this comparative example provides an optical transmittance testing device and its fabrication method. The fabrication method of the optical transmittance testing device includes:

[0160] LZO was spin-coated onto ITO to prepare an electron transport layer with a thickness of 60 nm and annealed at 80 °C for 15 minutes.

[0161] Comparative Example 2 (device without metal layer)

[0162] This comparative example provides a quantum light-emitting diode (LED). The device structure of the quantum dot LED is a positive structure, including: a substrate, an anode, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, a composite electron transport layer, and a cathode, which are stacked sequentially.

[0163] This comparative example also provides a method for fabricating the aforementioned quantum dot light-emitting diode, including:

[0164] S11: Provide a substrate and fabricate an anode with an ITO / Ag / ITO structure on the substrate;

[0165] S12: PEDOT:PSS:s-MoO3 was spin-coated onto the anode to prepare a hole injection layer with a thickness of 20 nm. The hole injection layer was then annealed in air at 180 °C for 15 minutes.

[0166] S13: In a nitrogen atmosphere, poly-TPD was spin-coated onto the hole injection layer to prepare a hole transport layer with a thickness of 15 nm and then annealed at 150 °C for 15 minutes.

[0167] S14: Spin-coat CdSe / ZnS onto 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;

[0168] S15: Spin-coat LZO onto the quantum dot light-emitting layer to prepare a 60nm thick film of the first electron transport material. The resulting device is then subjected to vertical irradiation with 254nm UV in a nitrogen atmosphere for 20 minutes.

[0169] S16: Before the first electron transport material film layer is completely cured, FeCl3 is spin-coated on the first electron transport material film 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.

[0170] S17: Ag is deposited on the composite electron transport layer to form a cathode with a thickness of 80 nm;

[0171] S18: Package.

[0172] In addition, this comparative example provides an optical transmittance testing device and its fabrication method. The fabrication method of the optical transmittance testing device includes:

[0173] LZO was spin-coated onto ITO to prepare a first electron transport material film with a thickness of 60 nm. The device was then irradiated vertically with 254 nm UV in a nitrogen atmosphere for 20 minutes. Before the first electron transport material film was completely cured, FeCl3 was spin-coated onto the first electron transport material film to prepare a metal salt film with a thickness of 3 nm. The film was then annealed at 80 °C for 15 minutes to form a composite electron transport layer.

[0174] Comparative Example 3

[0175] This comparative example provides a quantum light-emitting diode and its fabrication method. The quantum dot light-emitting diode is based on Comparative Example 2, except that the material FeCl3 in the metal salt film layer of the quantum dot light-emitting diode provided in Comparative Example 2 is replaced with CoCl2.

[0176] In addition, this comparative example provides an optical transmittance testing device and its preparation method. The optical transmittance testing device is based on Comparative Example 2, except that the material FeCl3 in the metal salt film layer of the optical transmittance testing device provided in Comparative Example 2 is replaced with CoCl2.

[0177] Comparative Example 4 (excluding metal salts)

[0178] This comparative example provides a quantum light-emitting diode (LED). The device structure of the quantum dot LED is a positive 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, which are stacked sequentially.

[0179] This comparative example also provides a method for fabricating the aforementioned quantum dot light-emitting diode, including:

[0180] S11: Provide a substrate and fabricate an anode with an ITO / Ag / ITO structure on the substrate;

[0181] S12: PEDOT:PSS:s-MoO3 was spin-coated onto the anode to prepare a hole injection layer with a thickness of 20 nm. The hole injection layer was then annealed in air at 180 °C for 15 minutes.

[0182] S13: In a nitrogen atmosphere, poly-TPD was spin-coated onto the hole injection layer to prepare a hole transport layer with a thickness of 15 nm and then annealed at 150 °C for 15 minutes.

[0183] S14: Spin-coat CdSe / ZnS onto 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;

[0184] S15: Spin-coat LZO onto 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;

[0185] S16: Ni is deposited on the electron transport layer to prepare a metal layer with a thickness of 2 nm;

[0186] S17: Ag is deposited on the electron transport layer to form a cathode with a thickness of 80 nm;

[0187] S18: Package.

[0188] In addition, this comparative example provides an optical transmittance testing device and its fabrication method. The fabrication method of the optical transmittance testing device includes:

[0189] LZO was spin-coated onto ITO to prepare an electron transport layer with a thickness of 60 nm, and then annealed at 80 °C for 15 minutes. Ni was then deposited on the electron transport layer to prepare a metal layer with a thickness of 2 nm.

[0190] Comparative Example 5

[0191] This comparative example provides a quantum light-emitting diode and its fabrication method. The quantum dot light-emitting diode is based on Comparative Example 4, except that the material Ni of the metal layer in the quantum dot light-emitting diode provided in Comparative Example 4 is replaced with Pd.

[0192] In addition, this comparative example provides an optical transmittance testing device and its preparation method. The optical transmittance testing device is based on Comparative Example 4, except that the material Ni of the metal layer in the optical transmittance testing device provided in Comparative Example 4 is replaced with Pd.

[0193] Comparative Example 6

[0194] This comparative example provides a quantum light-emitting diode and its fabrication method. The quantum dot light-emitting diode is based on Comparative Example 4, except that the material Ni of the metal layer in the quantum dot light-emitting diode provided in Comparative Example 4 is replaced with Pt.

[0195] In addition, this comparative example provides an optical transmittance testing device and its preparation method. The optical transmittance testing device is based on Comparative Example 4, except that the material Ni of the metal layer in the optical transmittance testing device provided in Comparative Example 4 is replaced with Pt.

[0196] Comparative Example 7 (excluding the non-high-temperature crosslinking operation of the film layer of the first electron transport material)

[0197] This comparative example provides a quantum dot light-emitting diode (LED) with a positive-position device structure, comprising: a substrate, an anode, a hole injection layer, a hole transport layer, a quantum dot light-emitting layer, a composite electron transport layer, a metal layer, and a cathode, which are sequentially stacked. The composite electron transport layer is made of a first electron transport material and a metal salt.

[0198] This embodiment also provides a method for fabricating the above-mentioned quantum dot light-emitting diode, including:

[0199] S11: Provide a substrate and fabricate an anode with an ITO / Ag / ITO structure on the substrate;

[0200] S12: PEDOT:PSS:s-MoO3 was spin-coated onto the anode to prepare a hole injection layer with a thickness of 20 nm. The hole injection layer was then annealed in air at 180 °C for 15 minutes.

[0201] S13: In a nitrogen atmosphere, poly-TPD was spin-coated onto the hole injection layer to prepare a hole transport layer with a thickness of 15 nm and then annealed at 150 °C for 15 minutes.

[0202] S14: Spin-coat CdSe / ZnS onto 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;

[0203] S15: Spin-coat 60nm LZO onto the quantum dot light-emitting layer to prepare a film layer of the first electron transport material;

[0204] S16: Instead of curing the film layer of the first electron transport material, FeCl3 is directly spin-coated onto the first electron transport material to prepare a metal salt film layer with a thickness of 3 nm, and then annealed at 80°C for 15 minutes.

[0205] S17: After the above metal salt film is completely cured, Ni is evaporated onto the deposited metal salt film to prepare a metal layer with a thickness of 2 nm.

[0206] S18: Deposit Ag onto the metal layer to form a cathode with a thickness of 80 nm;

[0207] S19: Package.

[0208] The optical transmittance testing devices in Examples 1 to 6 and Comparative Examples 1 to 6 were subjected to UV-VIS testing to calculate the thin film transmittance of the optical transmittance testing devices for light with wavelengths of 380 to 720 nm. The results are shown in Table 1.

[0209] Table 1. UV-VIS thin film transmittance test data (test range 380–720 nm)

[0210]

[0211] As can be seen from the data in the table, compared with most existing optical transmittance testing devices such as those provided in Comparative Example 1, the average transmittance and maximum transmittance of the optical transmittance testing devices including the composite electron transport layer and the metal layer provided in Examples 1 to 6 are increased.

[0212] Furthermore, the thin-film resistance of the quantum dot light-emitting diodes (LEDs) in Examples 2, 4, 6, Comparative Examples 1, and 3 was tested. The results showed that the thin-film resistance of the quantum dot LED prepared in Comparative Example 1 was around 100 Ω, the thin-film resistance of the quantum dot LED in Comparative Example 3 including a composite electron transport layer was 200–250 Ω, while the thin-film resistance of the quantum dot LEDs in Examples 2, 4, and 6, which simultaneously included a composite electron transport layer and a metal layer, was around 50–60 Ω. Therefore, the quantum dot LEDs that simultaneously included a composite electron transport layer and a metal layer had lower thin-film resistance, which was more conducive to carrier transport.

[0213] The brightness L and external quantum efficiency (EQE) performance values ​​of the quantum dot light-emitting diodes in Examples 1-6 and Comparative Examples 1-6 were tested and calculated using a JVL (current-voltage-luminance) tester. The results are shown in Table 2.

[0214] Table 2 Performance test data for devices 1-12

[0215]

[0216]

[0217] As can be seen from the data in Table 2, compared to most existing quantum dot light-emitting diodes (LEDs) such as those provided in Comparative Example 1, the external quantum efficiency and brightness of the quantum dot LEDs (including a composite electron transport layer and a metal layer as alternative electron transport layers) provided in Examples 1-6 are both improved. Furthermore, compared to the quantum dot LEDs provided in Comparative Example 1, the brightness of the quantum dot LEDs provided in Comparative Examples 2 and 3, which include a composite electron transport layer but no metal layer, is improved, but the external quantum efficiency does not change significantly, indicating that quantum dot LEDs with only a composite electron transport layer and no metal layer do not significantly improve the external quantum efficiency of the device. Compared to the quantum dot LEDs provided in Comparative Example 1, the external quantum efficiency of the quantum dot LEDs provided in Comparative Examples 4-6, which include a composite electron transport layer but no alternative electron transport layer, is significantly increased, but the brightness decreases, indicating that quantum dot LEDs with only a metal layer and no alternative electron transport layer do not significantly improve the brightness of the device. The quantum dot LEDs provided in Examples 1-6 of this invention exhibit superior performance in both external quantum efficiency and brightness.

[0218] In summary, the composite electron transport layer and the metal layer in the light-emitting diode provided by this invention complement each other and work together to give the light-emitting diode of this invention better performance in terms of transmittance, carrier transport, brightness and efficiency compared with the prior art, resulting in a better overall effect.

[0219] The above provides a detailed description of a light-emitting diode and its fabrication method according to the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A light-emitting diode, characterized in that, include: Anode, cathode, and light-emitting layer disposed between the anode and cathode; A composite electron transport layer is disposed between the cathode and the light-emitting layer. The composite electron transport layer is made of a first material and a second material; wherein the first material is a first electron transport material; and the second material is a metal salt, wherein the metal element in the metal salt is selected from group VIII elements; the metal salt is selected from one or more of cobalt chloride, ferric acetate, cobalt acetate, ferric stearate, ferric nitrate, and cobalt nitrate; in the composite electron transport layer, the first material and the second material are each independently formed into films and stacked together. A metal layer is disposed between the cathode and the composite electron transport layer, wherein a film layer of the second material is disposed close to the metal layer, and the material of the metal layer is a doped or undoped elemental metal, wherein the metal element in the elemental metal is selected from group VIII elements.

2. The light-emitting diode according to claim 1, characterized in that, In the composite electron transport layer, the molar ratio of the second material to the first material is 0.04 to 0.1; and / or The molar ratio of the metallic element to the first material is 0.02 to 0.

033.

3. The light-emitting diode according to claim 1, characterized in that, The metallic element is selected from one or more of nickel, palladium, and platinum; and / or The doping element of the metallic element is selected from group VIII elements, and the doping element is different from the metallic element in the metallic element.

4. The light-emitting diode according to claim 1, characterized in that, The first electron transport material is selected from one or more of doped or undoped metal oxides, doped or undoped semiconductor nanoparticles, and organic electron transport materials.

5. The light-emitting diode according to claim 1, characterized in that, The first electron transport material is selected from one or more of doped or undoped TiO2, ZnO, ZrO, SnO2, WO3, Ta2O3, HfO3, Al2O3, ZrSiO4, BaTiO3, BaZrO3, CdS, ZnSe, and ZnS; the doped element is selected from one or more of Al, Mg, In, Li, Ga, Cd, Cs, and Cu.

6. The light-emitting diode according to claim 1, characterized in that, The light-emitting diode is a normally positioned or inverted light-emitting diode; and / or The light-emitting diode is one of quantum dot light-emitting diodes, organic light-emitting diodes, or micron-sized light-emitting diodes.

7. The light-emitting diode according to claim 6, characterized in that, 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 one or more of 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, PbSTe, and PbSe / PbS.

8. A method for fabricating a light-emitting diode, characterized in that, include: An anode is provided, a light-emitting layer is formed on the anode, a stacked composite electron transport layer and a metal layer are deposited on the light-emitting layer, and a cathode is formed on the metal layer; or A cathode is provided, and a stacked metal layer and a composite electron transport layer are deposited on the cathode. A light-emitting layer is formed on the composite electron transport layer, and an anode is formed on the light-emitting layer. The composite electron transport layer comprises a first material and a second material; the first material is a first electron transport material; the second material is a metal salt, wherein the metal element in the metal salt is selected from group VIII elements; the metal salt is selected from one or more of cobalt chloride, ferric acetate, cobalt acetate, ferric stearate, ferric nitrate, and cobalt nitrate; in the composite electron transport layer, the first material and the second material are each independently formed into films and stacked, wherein the film layer of the second material is disposed close to the metal layer; The metal layer is made of a doped or undoped elemental metal, and the metal element in the elemental metal is selected from group VIII elements.

9. The method for preparing a light-emitting diode according to claim 8, characterized in that, The step of depositing the composite electron transport layer and the metal layer includes: The first electron transport material is deposited on the light-emitting layer, and the metal salt is deposited on the film layer of the first electron transport material before the film layer of the first electron transport material is cured, and the composite electron transport layer is formed by curing. Depositing the elemental metal on the composite electron transport layer to form a metal layer; or The step of depositing to form a stacked metal layer and a composite electron transport layer includes: A metal layer is formed by depositing the elemental metal on the cathode; The metal salt is deposited on the metal layer, and the first electron transport material is deposited on the metal salt film before the metal salt film is cured, and then cured to form a composite electron transport layer.

10. The method for fabricating a light-emitting diode according to claim 9, characterized in that, The curing of the composite electron transport layer is achieved by exposing the first electron transport material to air and / or by irradiation with ultraviolet light. Exposure to air includes placing the first electron transport material in an air environment for 0.25 to 1 minute; The ultraviolet irradiation method includes irradiating the first electron transport material with ultraviolet light for 0.25~30 minutes.

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