Light emitting diode and method of manufacturing the same

Abstract

The application discloses a light emitting diode and a preparation method thereof. The light emitting diode comprises an anode, a light emitting layer, an electron transport layer and a cathode which are sequentially stacked, wherein an electron transport transition layer is arranged between the electron transport layer and the cathode; the electron transport layer contains metal oxide, and the electron transport transition layer contains a nucleophilic reagent. A layer of electron transport transition layer containing a nucleophilic reagent is deposited between the electron transport layer and the cathode, the nucleophilic reagent has an unshared electron pair which can form a shared electron pair with oxide at the interface of the electron transport layer, can change the crystal structure of the oxide, can reduce the electron transport efficiency of the light emitting diode, achieves the effect of balancing the electron transport rate and the hole transport rate, and further improves the light emitting efficiency and service life of the light emitting diode.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of QLED, in particular to a light-emitting diode and a preparation method thereof. BACKGROUND

[0002] Electroluminescence is a new type of solid-state lighting technology, which has the advantages of low cost, light weight, fast response speed, high color saturation, etc., and has broad development prospects, and has become one of the important research directions of new generation LED display devices.

[0003] The light-emitting diode (QLED) based on semiconductor has better monochromaticity, color saturation and lower preparation cost, and has broad application prospects in display and lighting fields. After rapid development in recent years, the main performance indicators such as luminous brightness, external quantum efficiency (EQE) and service life have been greatly improved. How to make the QLED device have high brightness while maintaining high efficiency, long service life and high stability is a difficult problem to be solved in the QLED field, and is also a key technical bottleneck restricting its application in display and lighting fields.

[0004] Therefore, the prior art still needs to be improved and developed. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a light-emitting diode and a preparation method thereof, aiming at solving the problem of low luminous efficiency of the existing light-emitting diode.

[0006] A light-emitting diode comprises an anode, a light-emitting layer, an electron transport layer and a cathode which are sequentially stacked, wherein an electron transport transition layer is arranged between the electron transport layer and the cathode.

[0007] The electron transport layer contains metal oxide, and the electron transport transition layer contains nucleophilic reagent.

[0008] The light-emitting diode, wherein the material of the electron transport layer is metal oxide, and the material of the electron transport transition layer is nucleophilic reagent.

[0009] The light-emitting diode, wherein the structure formula of the nucleophilic reagent is wherein R1, R2 and R3 are independently selected from hydrocarbyl;

[0010] or, the structure formula of the nucleophilic reagent is wherein R4, R5 and R6 are independently selected from hydrocarbyl.

[0011] The light-emitting diode, wherein N or P in the nucleophilic reagent penetrates into the electron transport layer.

[0012] The light emitting diode, wherein the hydrocarbon group of the nucleophile is adsorbed on the cathode.

[0013] The light emitting diode, wherein the number of carbon atoms of the hydrocarbon group is greater than 5.

[0014] The light emitting diode, wherein the nucleophile is selected from one or more of trioctylamine, triphenylamine, trioctylphosphine, triphenylphosphine.

[0015] The light emitting diode, wherein the thickness of the electron transport transition layer is 1-5 nm.

[0016] The light emitting diode, wherein the material of the electron transport layer is selected from one or more of ZnO, TiO2, SnO2, Ta2O3, ZrO2, NiO, TiLiO, ZnAlO, ZnMgO, ZnSnO, ZnLiO, InSnO; and / or

[0017] The material of the light emitting layer is a quantum dot; and / or

[0018] The material of the light emitting layer is one or more of a II-VI compound quantum dot material, a III-V compound quantum dot material, a II-V compound quantum dot material, a III-VI compound quantum dot material, a IV-VI compound quantum dot material, a I-III-VI compound quantum dot material, a II-IV-VI compound quantum dot material, a IV monovalent quantum dot material; and / or

[0019] The material of the light emitting layer is one or more of a CdS quantum dot material, a CdSe quantum dot material, a CdTe quantum dot material, a ZnS quantum dot material, a ZnSe quantum dot material, a ZnTe quantum dot material, a HgS quantum dot material, a HgSe quantum dot material, a HgTe quantum dot material, a PbS quantum dot material, a PbSe quantum dot material, a PbTe quantum dot material, a GaP quantum dot material, a GaAs quantum dot material, a InP quantum dot material, a InAs quantum dot material.

[0020] A method for preparing a light emitting diode, comprising:

[0021] Providing an anode;

[0022] Forming a light emitting layer on the anode;

[0023] Forming an electron transport layer and an electron transport transition layer in sequence on the light emitting layer;

[0024] Forming a cathode on the electron transport transition layer;

[0025] Alternatively, providing a cathode;

[0026] forming an electron transport transition layer on the cathode;

[0027] forming a light emitting layer on the electron transport layer;

[0028] forming an anode on the light emitting layer;

[0029] wherein the electron transport layer contains metal oxide and the electron transport transition layer contains nucleophilic reagent.

[0030] the method for preparing the light emitting diode, wherein forming an electron transport layer and an electron transport transition layer on the light emitting layer comprises:

[0031] depositing an electron transport layer material and an electron transport transition layer material on the light emitting layer;

[0032] simultaneously annealing the deposited electron transport layer material and the electron transport transition layer material to form the electron transport layer and the electron transport transition layer.

[0033] the method for preparing the light emitting diode, wherein the annealing temperature is 60-100℃.

[0034] the method for preparing the light emitting diode, wherein the nucleophilic reagent has the structural formula wherein R1, R2, R3 are independently selected from hydrocarbon group;

[0035] or, the nucleophilic reagent has the structural formula wherein R4, R5, R6 are independently selected from hydrocarbon group.

[0036] the method for preparing the light emitting diode, wherein after depositing the electron transport layer material and the electron transport transition layer material, before the annealing, further comprising: treating the deposited electron transport transition layer material with ultraviolet light.

[0037] Beneficial effects: the present application deposits an electron transport transition layer containing nucleophilic reagent between the electron transport layer and the cathode, the nucleophilic reagent has unshared electron pair which can form shared electron pair with the metal oxide at the interface of the electron transport layer, can change the crystal structure of the metal oxide, reduce the electron transport rate, achieve the effect of balancing the electron transport rate and the hole transport rate, thereby improving the light emitting efficiency and the life of the light emitting diode. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a structural schematic diagram of the light emitting diode of the present application.

[0039] Figure 2 is another structural schematic diagram of the light emitting diode of the present application.

[0040] Figure 3 The flowchart illustrates the fabrication process of the light-emitting diode according to the present invention. Detailed Implementation

[0041] This invention provides a light-emitting diode and a method for fabricating the same. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0042] In the research process, balancing the injection of electrons and holes is an effective way to obtain high-efficiency QLED devices. In the currently mass-produced QLED devices, the electron transport layer material is made of metal oxide particles, such as nano-inorganic zinc oxide nanoparticles. The above-mentioned electron transport layer materials have high charge mobility and very low electron injection barriers. However, for holes, organic polymer materials are usually used as hole transport layer materials. Not only do they have lower mobility, but they also have relatively large injection barriers, thus leading to an imbalance between electron and hole transport rates.

[0043] The imbalance between electron and hole transport rates leads to unstable carrier recombination in the light-emitting layer. Excessive electron injection causes self-emission in functional layers of QLED devices, such as the hole transport layer, thus affecting the luminescence purity and recombination efficiency of the device. Furthermore, if the transport of excessively injected electrons is hindered in the light-emitting layer, charge will accumulate, severely impacting luminescence characteristics and the lifespan of the device.

[0044] To balance electron and hole transport rates, insulating polymer materials are used as electron transport transition layers. However, these materials only act as electron blocking agents and cannot reduce the electron transport rate. Furthermore, polymer materials have poor film-forming properties, poor thermal stability, and are prone to aging and degradation, thus affecting device lifespan.

[0045] like Figure 1 As shown, an embodiment of the present invention provides a light-emitting diode, comprising: an anode 1, a light-emitting layer 4, an electron transport layer 5, and a cathode 7 stacked sequentially, wherein an electron transport transition layer 6 is disposed between the electron transport layer 5 and the cathode 7;

[0046] The electron transport layer 5 contains a metal oxide, and the electron transport transition layer 6 contains a nucleophile.

[0047] The present application deposits an electron transport transition layer 6 containing a nucleophile between the electron transport layer 5 and the cathode 7, wherein the nucleophile has an unshared electron pair capable of forming a shared electron pair with the metal oxide at the interface of the electron transport layer 5, which can change the crystal structure of the metal oxide and reduce the electron transport rate, so as to balance the electron transport rate and the hole transport rate, thereby improving the luminous efficiency and the service life of the light emitting diode.

[0048] The nucleophile described in the present embodiment is a neutral molecule or a negative ion having an unshared electron pair, which is an electron pair donor. Specifically, the nucleophile can donate an electron or a shared electron to bond with other molecules or ions. The electron transport layer 5 uses a metal oxide as the electron transport material, and the oxygen atom itself is short of one pair of electrons. The extra electron in the nucleophile can form a shared electron pair with O, that is, the oxygen atom at the interface of the electron transport layer 5 and the electron transport transition layer 6 forms an electron pair with the nucleophile, which can partially change the crystal structure of the electron transport material and reduce the electron transport efficiency in the electron transport layer 5.

[0049] In an embodiment of the present application, the material of the electron transport layer is a metal oxide, and the material of the electron transport transition layer is a nucleophile. That is, the electron transport layer can be formed of a metal oxide, and the electron transport transition layer can be formed of a nucleophile.

[0050] The present embodiment can use a nucleophile with moderate reactivity as the material of the electron transport transition layer 6, such as a nitrogen-containing nucleophile and a phosphorus-containing nucleophile. In an embodiment of the present application, the nucleophile has the structural formula wherein R1, R2, R3, R4, R5, and R6 are each independently selected from a hydrocarbon group.

[0051] The nucleophile has the structural formula which is a claw-shaped nucleophile (cone-shaped nucleophile), and specifically, the three claw chains are hydrocarbon groups, which can be the same or different, and are electron-donating groups. The electron density tends to accumulate on the N and P atoms, and the N and P atoms themselves have an unshared electron pair, so the claw-shaped nucleophile has strong electron pair donating ability. The unshared electron pair in the nucleophile attempts to pair with the O atom in the electron transport material to form an N---O---Zn structure or a P---O---Zn structure, so that the crystal structure of the oxide electron transport material is slightly destroyed, thereby reducing the electron transport rate of the electron transport material to a certain extent, promoting the balance between electron and hole transport, and improving the luminous efficiency and the service life of the QLED.

[0052] In the embodiment of the present application, the claw-shaped nucleophile and the metal oxide material of the electron transport layer 5 can realize self-assembly. Specifically, the N or P atom is automatically attracted to the electron transport layer 5, while the three claw chains are repelled from the electron transport layer 5. That is, the light-emitting diode, wherein the hydrocarbon group of the nucleophile is directed toward the cathode 7, and the N or P is directed toward the electron transport layer 5. The nucleophile is a claw-shaped nucleophile, and the spatial configuration is a cone shape, wherein the N or P corresponds to one vertex of a triangular pyramid, and the three hydrocarbon groups correspond to the other three vertices of the triangular pyramid. The N or P atom has a strong electron pair supply capability, and can be automatically attracted to the electron-deficient atom in the oxide in the electron transport layer 5, so that the N or P is automatically directed toward the electron transport layer 5, and the hydrocarbon group of the nucleophile is directed toward the cathode 7. In other words, the N or P directed toward the electron transport layer 5 means that the N or P in the nucleophile is closer to the electron transport layer 5 than the hydrocarbon group.

[0053] In the embodiment of the present application, the N or P in the nucleophile penetrates into the electron transport layer 5, thereby reducing the film-forming interface defects between the cathode and the electron transport layer 5. Specifically, the claw-shaped nucleophile has an inverted triangular pyramid structure, and the N or P atom can penetrate into the electron transport layer 5 to fill the film-forming defects of the electron transport material, thereby improving the light-emitting efficiency of the QLED device. At the same time, the claw-shaped nucleophile electron transport material has good dielectric properties, and has the same electron blocking effect as the existing polymer electron transport material.

[0054] In the embodiment of the present application, the hydrocarbon group in the nucleophile is adsorbed on the cathode. Specifically, after the electron cloud in the nucleophile tends to be close to the N or P atom, the hydrocarbon group branch itself is electron-deficient, and the mutual attraction force to the metal cathode is increased, thereby exhibiting a certain viscosity to make the hydrocarbon group adsorbed on the cathode. In an embodiment of the present application, the hydrocarbon group branch itself in the nucleophile has a similar flexibility of a polymer, and can also produce a certain viscosity to the cathode.

[0055] In an embodiment of the present application, the number of C atoms in the hydrocarbon group is greater than 5. Specifically, the electron transport transition layer material is a claw-shaped nucleophile based on a long straight-chain hydrocarbon group, that is, the hydrocarbon group is a straight-chain hydrocarbon group and the number of C atoms in the hydrocarbon group is greater than 5, such as trioctylamine, trioctylphosphine, etc., which can make the nucleophile in the electron transport transition layer 6 have a certain degree of orientation. The orientation can increase the delocalization of the charge, reduce the potential barrier in the charge transfer, and improve the light-emitting efficiency of the QLED device.

[0056] In one embodiment of the present invention, the hydrocarbon group can be a hydrocarbon group with high steric hindrance, such as the nucleophile selected from one or more of triphenylphosphine and triphenylamine. The presence of a hydrocarbon group with high steric hindrance in the aforementioned nucleophile can improve the compactness of the electron transport transition layer 6, and to a certain extent prevent water and oxygen from entering other functional layers of the device, thus providing a certain degree of protection.

[0057] In one embodiment of the present invention, the claw-shaped nucleophile molecules in the claw-shaped nucleophile electron transition transport layer are arranged in a single layer. Specifically, the thickness of the electron transport transition layer 6 is 1 nm to 5 nm.

[0058] like Figure 2 As shown, in one embodiment of the present invention, the light-emitting diode further includes a hole functional layer disposed between the anode 1 and the light-emitting layer 4. Further, the hole functional layer may be composed of a hole injection layer and a hole injection layer. The QLED structure described in this embodiment, from bottom to top, consists of an anode (bottom electrode) 1, a hole injection layer 2, a hole transport layer 3, a light-emitting layer 4, an electron transport layer 5, an electron transport transition layer 6, and a cathode (top electrode) 7.

[0059] In one embodiment of the present invention, the material of the anode 1 may be selected from one or more of indium-doped tin oxide (ITO), fluorine-doped tin oxide (FTO), antimony-doped tin oxide (ATO), and aluminum-doped zinc oxide (AZO).

[0060] In one embodiment of the present invention, the hole injection layer 2 is made of one or more of poly(3,4-ethylenedioxythiophene)-polystyrene sulfonic acid (PEDOT:PSS), undoped transition metal oxides, doped transition metal oxides, metal sulfides, and doped metal sulfides.

[0061] In one embodiment of the present application, the material of the hole transport layer 3 can be selected from organic materials having hole transport ability, including but not limited to poly(9,9-dioctylfluorene-CO-N-(4-butylphenyl)diphenylamine) (TFB), polyvinylcarbazole (PVK), poly(N,N'bis(4-butylphenyl)-N,N'-bis(phenyl)benzidine) (poly-TPD), poly(9,9-dioctylfluorene-co-bis-N,N-phenyl-1,4-phenylenediamine) (PFB), 4,4',4"-tris(carbazol-9-yl)triphenylamine (TCTA), 4,4'-bis(9-carbazolyl) biphenyl (CBP), N,N'-diphenyl-N,N'-di(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD), N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), or mixtures thereof; the material of the hole transport layer 3 can also be selected from inorganic materials having hole transport ability, such as selected from but not limited to doped or undoped NiO, WO3, MoO3, CuO, doped graphene, undoped graphene, C60, and mixtures of the above inorganic materials.

[0062] In one embodiment of the present application, the quantum dot light emitting layer 4 employs quantum dot materials including but not limited to one or more of II-VI compound quantum dot materials, III-V compound quantum dot materials, II-V compound quantum dot materials, III-VI compound quantum dot materials, IV-VI compound quantum dot materials, I-III-VI compound quantum dot materials, II-IV-VI compound quantum dot materials, or IV monometallic quantum dot materials.

[0063] In one embodiment of the present application, the material of the light emitting layer is a quantum dot. That is, the light emitting layer of the present application can be a quantum dot light emitting layer, and the light emitting device is a quantum dot light emitting diode (QLED).

[0064] In one embodiment of the present application, the material used in the light-emitting layer 4 includes, but is not limited to, nanocrystals of II-VI semiconductors, such as CdS quantum dot material, CdSe quantum dot material, CdTe quantum dot material, ZnS quantum dot material, ZnSe quantum dot material, ZnTe quantum dot material, HgS quantum dot material, HgSe quantum dot material, HgTe quantum dot material, PbS quantum dot material, PbSe quantum dot material, PbTe quantum dot material, and other binary, ternary, quaternary II-VI compound materials; nanocrystals of III-V semiconductors, such as GaP quantum dot material, GaAs quantum dot material, InP quantum dot material, InAs quantum dot material, and other binary, ternary, quaternary III-V compound quantum dot materials; the semiconductor material for electroluminescence is not limited to II-V compound quantum dot materials, III-V compound quantum dot materials, IV-VI compound quantum dot materials, I-III-VI compound quantum dot materials, II-IV-VI compound quantum dot materials, IV monovalent quantum dot materials, etc.

[0065] In one embodiment of the present application, the electron transport layer 5 includes oxide semiconductor nanoparticle materials with electron transport capability and a band gap greater than that of the light-emitting material, including but not limited to one or more of ZnO, TiO2, SnO2, Ta2O3, ZrO2, NiO, TiLiO, ZnAlO, ZnMgO, ZnSnO, ZnLiO, InSnO.

[0066] In one embodiment of the present application, the material of the cathode 7 described in this embodiment includes one or more of metal materials, carbon materials, and metal oxides. The metal materials include one or more of Al, Ag, Cu, Mo, Au, Ba, Ca, and Mg. The carbon materials include one or more of graphite, carbon nanotubes, graphene, and carbon fibers. The metal oxides can be doped or undoped metal oxides, including one or more of ITO, FTO, ATO, AZO, GZO, IZO, MZO, and AMO, and also include composite electrodes with a metal sandwiched between doped or undoped transparent metal oxides, wherein the composite electrodes include one or more of AZO / Ag / AZO, AZO / Al / AZO, ITO / Ag / ITO, ITO / Al / ITO, ZnO / Ag / ZnO, ZnO / Al / ZnO, TiO2 / Ag / TiO2, TiO2 / Al / TiO2, ZnS / Ag / ZnS, ZnS / Al / ZnS, TiO2 / Ag / TiO2, and TiO2 / Al / TiO2.

[0067] The unshared electron pair of the nucleophile and the oxide of the interface of the electron transport layer 5 form a shared electron pair, which reduces the electron transport rate, improves the light emitting efficiency and the service life of the light emitting diode; and the self-assembly rearrangement of the nucleophile and the oxide of the electron transport layer 5 also forms a grafted mosaic structure, specifically, the N\P atom can penetrate into the electron transport layer 5 and fill the film defect of the electron transport material, thereby improving the light emitting effect and the service life of the light emitting diode; meanwhile, the nucleophile with high steric hindance hydrocarbon group can improve the compactness of the electron transport transition layer 6, which can isolate water and oxygen from entering other functional layers of the device to a certain extent, thereby further improving the efficiency and the service life of the light emitting diode.

[0068] The embodiment of the present application provides a preparation method of the light emitting diode.

[0069] S101, providing an anode 1;

[0070] S102, forming a light emitting layer 4 on the anode 1;

[0071] S103, sequentially forming an electron transport layer 5 and an electron transport transition layer 6 on the light emitting layer 4;

[0072] S104, forming a cathode 7 on the electron transport transition layer 6;

[0073] Alternatively, S201, providing a cathode 7;

[0074] S202, sequentially forming an electron transport transition layer 6 and an electron transport layer 5 on the cathode 7;

[0075] S203, forming a light emitting layer 4 on the electron transport layer 5;

[0076] S204, forming an anode 1 on the light emitting layer 4;

[0077] The electron transport layer 5 contains metal oxide, and the electron transport transition layer 6 contains a nucleophile.

[0078] The embodiment is a preparation scheme of the light emitting diode in which a layer of the electron transport transition layer 6 containing the nucleophile is deposited on the electron transport layer 5. Specifically, a layer of the electron transport transition layer containing the nucleophile is deposited between the electron transport layer and the cathode, the nucleophile has an unshared electron pair which can form a shared electron pair with the oxide at the interface of the electron transport layer, can change the crystal structure of the oxide, reduce the electron transport rate, achieve the effect of balancing the electron transport rate and the hole transport rate, thereby improving the efficiency and the service life of the light emitting diode.

[0079] In the embodiment, the S103 specifically includes:

[0080] S1031, depositing an electron transport layer material and an electron transport transition layer material on the light emitting layer 4 in sequence;

[0081] S1032, annealing the deposited electron transport layer material and the electron transport transition layer material simultaneously to form an electron transport layer 5 and an electron transport transition layer 6.

[0082] The embodiment of the present application simultaneously anneals the deposited electron transport layer material and the electron transport transition layer material, that is, after depositing the metal electron transport layer material, the metal electron transport layer material is not annealed first, and then the transition transport layer material containing the claw-shaped nucleophilic reagent electron is deposited, and then one step of annealing is performed. By not annealing after depositing the electron transport layer material, the electron transport layer material has not been annealed into shape at this time, which is beneficial to the penetration of the claw-shaped nucleophilic reagent P or N into the electron transport layer 5, so that the nucleophilic reagent and the oxide in the electron transport layer material fully perform electron pairing.

[0083] In the embodiment, the S203 specifically includes:

[0084] S2031, depositing an electron transport transition layer material and an electron transport layer material on the cathode 7 in sequence;

[0085] S2032, annealing the deposited electron transport transition layer material and the electron transport layer material simultaneously to form an electron transport transition layer 6 and an electron transport layer 5.

[0086] In the S203, the oxide electron transport material should be deposited immediately (such as within 0.2-10 minutes) after depositing the electron transport transition layer material, and then annealing treatment is performed immediately, which is beneficial to ensuring the integrity of the electron transport transition layer.

[0087] In the embodiment, the structure formula of the nucleophilic reagent is wherein R1, R2, R3 are independently selected from a hydrocarbon group;

[0088] Alternatively, the structure formula of the nucleophilic reagent is wherein R4, R5, R6 are independently selected from a hydrocarbon group. In the embodiment, a layer of electron transport transition layer 6 containing a claw-shaped nucleophilic reagent is deposited between the electron transport layer 5 and the cathode 7, a sandwich structure film is formed through electron pairing self-assembly, which plays a role of reducing the electron transport efficiency, reducing the interface defects, and improving the light emitting efficiency and the service life of the light emitting diode.

[0089] In one embodiment of the present application, before depositing the light emitting layer 4 on the anode 1, it further includes depositing a hole functional layer on the anode 1. Optionally, the hole functional layer includes a hole injection layer 2 and a hole transport layer 3.

[0090] Specifically, the preparation method of the light emitting diode comprises:

[0091] S101, providing an anode 1;

[0092] S105, sequentially depositing a hole injection layer 2 and a hole transport layer 3 on the anode 1;

[0093] S102, depositing a light emitting layer 4 on the hole transport layer 3;

[0094] S103, sequentially depositing an electron transport layer material and an electron transport transition layer material on the light emitting layer 4, and forming an electron transport layer 5 and an electron transport transition layer 6 after annealing;

[0095] S104, depositing a cathode 7 on the electron transport transition layer 6.

[0096] In the S101, the anode 1 is a transparent anode substrate (anode substrate).

[0097] In the S105, the hole functional layer comprises a hole injection layer 2 and a hole transport layer 3.

[0098] Specifically, the S105 comprises: depositing a hole injection layer 2 on the transparent anode substrate 1; and depositing a hole transport layer 3 on the hole injection layer 2.

[0099] In the S102, a light emitting layer material (such as a quantum dot material) is deposited on the hole transport layer 3 to obtain the light emitting layer 4.

[0100] In the S103, the electron transport layer material is a metal oxide nanomaterial. The deposition of the electron transport layer material is specifically performed by using a solution method, and an alcohol solvent is used in the deposition process. After the deposition of the electron transport layer material, a layer of electron transport transition layer material is deposited, and finally annealing is performed to form the electron transport layer 5 and the electron transport transition layer 6.

[0101] Specifically, the S103 comprises: depositing an electron transport layer 5 on the light emitting layer 4 by using a solution method; depositing an electron transport transition material on the electron transport layer 5, annealing, removing excess gas and solvent, and fully self-assembling the electron transport transition layer 6.

[0102] In this embodiment, after the solution method is used to deposit the metal electron transport layer 5 solution, annealing is not performed first, and the electron transition transport layer 6 of the claw-shaped nucleophilic reagent is deposited and then annealed, so that a small amount of claw-shaped nucleophilic reagent P and N penetrates into the electron transport layer 5, so that it is fully electron-paired self-assembled. The molecules of the claw-shaped nucleophilic reagent in the electron transition transport layer are arranged in a single layer, and the thickness is in the range of 1-5 nm.

[0103] In one embodiment of the present application, the annealing temperature is 60-100℃, which can effectively remove excess gas and solvent.

[0104] In one embodiment of the present application, the annealing time is 20-90min, which ensures the claw-shaped nucleophile has sufficient time to complete self-assembly.

[0105] In S104, the metal cathode 7 is vacuum evaporated on the claw-shaped electron transport transition material.

[0106] In one embodiment of the present application, after the deposition of the electron transport layer material and the electron transport transition layer material, the deposited electron transport transition layer material is subjected to ultraviolet light irradiation treatment before the annealing. The ultraviolet light irradiation treatment can provide a certain driving force for the self-assembly of the nucleophile and the oxide, i.e., it is conducive to the formation of a common electron pair between the nucleophile and the metal oxide of the electron transport layer.

[0107] The preparation method of the light-emitting diode further comprises:

[0108] S106, encapsulating the light-emitting diode.

[0109] The encapsulation adhesive material in this embodiment is a resin material, such as epoxy resin, which includes its monomer, prepolymer, polymer, initiator and other additives. The encapsulation method includes one of frame adhesive and point adhesive.

[0110] The technical solutions of the present application will be described below through specific embodiments.

[0111] Embodiment 1

[0112] Preparation method of QLED containing claw-shaped nucleophile electron transport transition layer:

[0113] Step 1: deposit PEDOT:PSS as a hole injection layer 2 on a transparent ITO anode substrate 1;

[0114] Step 2: deposit TFB as a hole transport layer 3 on the hole injection layer 2;

[0115] Step 3: deposit CdS quantum dot material on the hole transport layer 3 to form a light-emitting layer 4;

[0116] Step 4: deposit ZnO ethanol solution on the light-emitting layer 4 without annealing to form a zinc oxide ethanol solution substrate;

[0117] Step 5: On the above ZnO ethanol solution substrate, deposit a layer of trioctylphosphine, then anneal at 80°C for 30 min, so that the trioctylphosphine is fully rearranged to form a common electron pair with the ZnO, forming a ZnO electron transport layer 5 and a claw-shaped nucleophile electron transport transition layer 6;

[0118] Step 6: On the above nucleophile electron transport transition layer 6, deposit a silver metal cathode 7 by evaporation;

[0119] Step 7: Package.

[0120] Example 2

[0121] Preparation method of QLED containing a claw-shaped nucleophile electron transport transition layer:

[0122] Step 1: On a transparent ITO anode substrate 1, deposit PEDOT:PSS as a hole injection layer 2;

[0123] Step 2: On the hole injection layer 2, deposit TFB as a hole transport layer 3;

[0124] Step 3: On the hole transport layer 3, deposit CdS quantum dot material to form a light-emitting layer 4;

[0125] Step 4: On the light-emitting layer 4, deposit a ZnO ethanol solution without annealing, forming a ZnO ethanol solution substrate;

[0126] Step 5: On the above ZnO ethanol solution substrate, deposit a layer of trioctylphosphine, then anneal at 80°C for 30 min, so that the trioctylphosphine is fully rearranged to form a common electron pair with the ZnO, forming a ZnO electron transport layer 5 and a claw-shaped nucleophile electron transport transition layer 6;

[0127] Step 6: On the above nucleophile electron transport transition layer 6, deposit a silver metal cathode 7 by evaporation;

[0128] Step 7: Package.

[0129] Example 3

[0130] Preparation method of QLED containing a claw-shaped nucleophile electron transport transition layer:

[0131] Step 1: On a transparent ITO anode substrate 1, deposit PEDOT:PSS as a hole injection layer 2;

[0132] Step 2: On the hole injection layer 2, deposit TFB as a hole transport layer 3;

[0133] Step 3: On the hole transport layer 3, deposit CdS quantum dot material to form a light-emitting layer 4;

[0134] Step 4: On the light emitting layer 4, deposit ZnO ethanol solution, without annealing, to form a zinc oxide ethanol solution substrate;

[0135] Step 5: On the above zinc oxide ethanol solution substrate, deposit a layer of triphenylphosphine, anneal at 80°C for 30 min, so that the triphenylphosphine is fully rearranged to form a common electron pair with the zinc oxide, to form a zinc oxide electron transport layer 5 and a claw-shaped nucleophile electron transport transition layer 6;

[0136] Step 6: On the above nucleophile electron transport transition layer 6, deposit a silver metal cathode 7 by evaporation;

[0137] Step 7: Package.

[0138] Example 4

[0139] Method for preparing a QLED containing a claw-shaped nucleophile electron transport transition layer:

[0140] Step 1: Deposit a layer of triphenylphosphine on the silver metal cathode 7, without annealing;

[0141] Step 2: Deposit ZnO ethanol solution on the triphenylphosphine, anneal at 80°C for 30 min, so that the triphenylphosphine is fully rearranged to form a common electron pair with the zinc oxide electron transport layer 5, to form a claw-shaped nucleophile electron transport transition layer 6 and an electron transport layer 5;

[0142] Step 3: On the electron transport 5, deposit CdS quantum dot material to form a light emitting layer 4;

[0143] Step 4: On the light emitting layer 4, deposit TFB as a hole transport layer 3;

[0144] Step 5: On the hole transport layer 3, deposit PEDOT:PSS as a hole injection layer 2;

[0145] Step 6: Form an ITO anode 1 on the hole injection layer 2;

[0146] Step 7: Package.

[0147] It should be understood that the application of the present application is not limited to the above examples, and can be improved or modified according to the above description by those of ordinary skill in the art, and all such improvements and modifications shall fall within the scope of protection of the appended claims of the present application.

Claims

1. A light emitting diode comprising: The anode, the light-emitting layer, the electron transport layer and the cathode are sequentially stacked, characterized in that an electron transport transition layer is arranged between the electron transport layer and the cathode, the electron transport layer contains metal oxide, and the electron transport transition layer contains nucleophilic reagent. The structure of the nucleophile is wherein R1, R2, R3are each independently selected from hydrocarbyl groups; Alternatively, the nucleophile has the structural formula wherein R4, R5, R6are each independently selected from a hydrocarbyl group; The hydrocarbon group is a linear hydrocarbon group, and the number of carbon atoms of the hydrocarbon group is greater than 5.

2. The light emitting diode of claim 1, wherein, The material of the electron transport layer is metal oxide, and the material of the electron transport transition layer is nucleophilic reagent.

3. The light emitting diode of claim 1, wherein, N or P in the nucleophilic reagent penetrates into the electron transport layer.

4. The light emitting diode of claim 1, wherein, The hydrocarbon group in the nucleophilic reagent is adsorbed on the cathode.

5. The light emitting diode of claim 1, wherein, The nucleophilic reagent is selected from one or more of trioctylamine, triphenylamine, trioctylphosphine and triphenylphosphine.

6. The light emitting diode of claim 1, wherein, The thickness of the electron transport transition layer is 1 nm to 5 nm.

7. The light emitting diode of claim 1, wherein, The metal oxide is selected from one or more of ZnO, TiO2, SnO2, Ta2O3, ZrO2, NiO, TiLiO, ZnAlO, ZnMgO, ZnSnO, ZnLiO and InSnO; or The material of the light-emitting layer is one or more of II-VI compound quantum dot material, III-V compound quantum dot material, II-V compound quantum dot material, III-VI compound quantum dot material, IV-VI compound quantum dot material, I-III-VI compound quantum dot material, II-IV-VI compound quantum dot material and IV compound single quantum dot material; or The material of the light-emitting layer is one or more of CdS quantum dot material, CdSe quantum dot material, CdTe quantum dot material, ZnS quantum dot material, ZnSe quantum dot material, ZnTe quantum dot material, HgS quantum dot material, HgSe quantum dot material, HgTe quantum dot material, PbS quantum dot material, PbSe quantum dot material, PbTe quantum dot material, GaP quantum dot material, GaAs quantum dot material, InP quantum dot material and InAs quantum dot material.

8. A method for fabricating a light-emitting diode, characterized in that, Comprising: providing an anode; forming a light-emitting layer on the anode; forming an electron transport layer and an electron transport transition layer on the light-emitting layer in sequence; forming a cathode on the electron transport transition layer; Alternatively, providing a cathode; forming an electron transport transition layer and an electron transport layer on the cathode in sequence; forming a light-emitting layer on the electron transport layer; forming an anode on the light-emitting layer; The electron transport layer contains metal oxide, and the electron transport transition layer contains nucleophilic reagent. The structure of the nucleophile is wherein R1, R2, R3are each independently selected from hydrocarbyl groups; Alternatively, the nucleophile has the structural formula wherein R4, R5, R6are each independently selected from a hydrocarbyl group; The hydrocarbon group is a linear hydrocarbon group, and the number of carbon atoms of the hydrocarbon group is greater than 5.

9. The method of claim 8, wherein the substrate is a sapphire substrate. Forming an electron transport layer and an electron transport transition layer on the light-emitting layer in sequence specifically includes: depositing electron transport layer material and electron transport transition layer material on the light-emitting layer in sequence; simultaneously annealing the deposited electron transport layer material and electron transport transition layer material to form the electron transport layer and the electron transport transition layer.

10. The method of claim 9, wherein the LED is formed on a substrate. The annealing temperature is 60°C to 100°C.

11. The method of claim 9, wherein the substrate is a sapphire substrate. After depositing the electron transport layer material and the electron transport transition layer material, the process further includes, before the annealing, ultraviolet irradiation treatment of the deposited electron transport transition layer material.

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