Composite nanoparticles, quantum dot light-emitting diodes and preparation methods

Abstract

The present invention discloses a composite nanoparticle, a quantum dot light-emitting diode, and a preparation method. The composite nanoparticles include oxide nanoparticles containing hydroxyl groups on their surfaces and a passivating agent containing a phosphorus-oxygen double bond. The hydroxyl groups on the surfaces of the oxide nanoparticles form hydrogen bonds with the phosphorus-oxygen double bonds in the passivating agent. In the present invention, the phosphorus-oxygen double bonds in the passivating agent easily interact with the hydroxyl groups on the surfaces of the oxide nanoparticles to form hydrogen bonds, thereby passivating the oxide nanoparticles and reducing surface defects.

Description

Technical Field

[0001] The present invention relates to the field of quantum dots, and in particular to composite nanoparticles, quantum dot light-emitting diodes and preparation methods. Background Art

[0002] Quantum dots (QLEDs) have recently attracted widespread attention due to their advantages, including high color purity, high quantum efficiency, tunable emission color, and high quantum yield, as well as their ability to be fabricated using printing processes. Their performance metrics have also rapidly improved. In QLED devices, N-type oxide nanoparticles are widely used as electron transport layer materials due to their high transmittance, high electron mobility, low cost, environmental compatibility, and simple fabrication process. This has significantly improved device efficiency, but it still cannot address the issue of short device lifetime. This is because most N-type oxide nanoparticles have a large number of hydroxyl groups on their surfaces. These hydroxyl groups are easily oxidized under prolonged power supply and environmental influences, generating highly oxidizing OH radicals. These reactive OH radicals can oxidize a wide range of organic compounds, leading to ligand shedding on the quantum dot surface, increased surface defects in the oxide nanoparticles, and increased carrier transport barriers, significantly reducing the lifetime of QLED devices.

[0003] Therefore, the existing technology still needs to be improved and developed. Summary of the Invention

[0004] In view of the above-mentioned deficiencies in the prior art, the object of the present invention is to provide a composite nanoparticle, a quantum dot light-emitting diode and a preparation method, aiming to solve the problem of surface defects in existing oxide nanoparticles.

[0005] The technical solutions of the present invention are as follows:

[0006] A composite nanoparticle comprises an oxide nanoparticle containing hydroxyl groups on the surface and a passivator containing a phosphorus-oxygen double bond. The hydroxyl groups on the surface of the oxide nanoparticle form hydrogen bonds with the phosphorus-oxygen double bonds in the passivator.

[0007] The composite nanoparticles, wherein the passivating agent is triphenylphosphine oxide.

[0008] The composite nanoparticles, wherein the passivating agent is a triphenylphosphine oxide derivative, and the triphenylphosphine oxide derivative is One of the above, wherein R1, R2 and R3 are large π bond groups; the large π bond group is directly connected to the triphenylphosphine oxide, or the large π bond group is connected to the triphenylphosphine oxide through a group containing a π bond.

[0009] In the composite nanoparticles, the large π bond group is a benzene ring or a butadiene vinyl group; and / or the group containing a π bond is a vinyl group or an acetylene group.

[0010] The composite nanoparticles, wherein the oxide nanoparticles are one or more of ZnO, TiO2, SnO2, Ta2O3, ZnMgO, ZnAlO and SnInO.

[0011] The composite nanoparticles are ZnO containing hydroxyl groups on the surface and triphenylphosphine oxide forming hydrogen bonds with the hydroxyl groups.

[0012] A quantum dot light-emitting diode comprises an electron transport layer, wherein the material of the electron transport layer is the composite nanoparticles described in the present invention.

[0013] The quantum dot light-emitting diode further comprises a cathode, an anode, and a quantum dot light-emitting layer arranged between the cathode and the anode, and the electron transport layer is arranged between the cathode and the quantum dot light-emitting layer.

[0014] A method for preparing a quantum dot light-emitting diode, comprising the steps of:

[0015] providing a substrate;

[0016] A composite nanoparticle solution is deposited on the substrate to prepare an electron transport layer. The composite nanoparticle solution includes organic alcohol and the composite nanoparticles according to the present invention dispersed in the organic alcohol.

[0017] In the method for preparing the quantum dot light-emitting diode, the mass fraction of the composite nanoparticle solution is 0.1-10%.

[0018] Beneficial effects: In the composite nanoparticles provided by the present invention, the phosphorus-oxygen double bond in the passivator can easily interact with the hydroxyl groups on the surface of the oxide nanoparticles to form hydrogen bonds, thereby passivating the oxide nanoparticles and reducing their surface defects. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a structural schematic diagram of a preferred embodiment of a positive-type quantum dot light-emitting diode of the present invention.

[0020] Figure 2 This is a structural schematic diagram of a preferred embodiment of an inversion structure quantum dot light emitting diode of the present invention.

[0021] Figure 3 The present invention is a flow chart of a preferred embodiment of a method for preparing a positive-type quantum dot light-emitting diode.

[0022] Figure 4 The present invention is a flowchart of a preferred embodiment of a method for preparing an inversion structure quantum dot light-emitting diode. DETAILED DESCRIPTION

[0023] The present invention provides a composite nanoparticle, a quantum dot light-emitting diode, and a preparation method. To clarify the objectives, technical solutions, and effects of the present invention, the present invention is described in further detail below. It should be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention.

[0024] There are a large number of -OH (hydroxyl) groups on the surface of oxide nanoparticles. These -OH groups are easily oxidized under long-term power-on conditions and the influence of the surrounding environment, generating highly oxidizing OH free radicals. Active OH free radicals can oxidize many organic substances, resulting in the shedding of ligands on the surface of quantum dots, increased surface defects of oxide nanoparticles, and increased carrier transfer barriers, thereby seriously reducing the luminous efficiency and service life of QLED devices.

[0025] Based on the problems existing in the prior art, an embodiment of the present invention provides a nanocomposite particle, which includes oxide nanoparticles containing hydroxyl groups on the surface and a passivator containing phosphorus-oxygen double bonds. The hydroxyl groups on the surface of the oxide nanoparticles form hydrogen bonds with the phosphorus-oxygen double bonds in the passivator.

[0026] In this embodiment, the oxygen atom in the phosphorus-oxygen double bond of the passivating agent can interact with the hydroxyl groups on the surface of the oxide nanoparticles to form hydrogen bonds, thereby passivating the surface of the oxide nanoparticles and reducing surface defects.

[0027] In some embodiments, the passivating agent is triphenylphosphine oxide, which has the chemical formula The oxygen atoms in the phosphorus-oxygen double bonds of the triphenylphosphine oxide interact with hydroxyl groups on the surface of the oxide nanoparticles to form hydrogen bonds, thereby passivating the oxide nanoparticles. In addition, the triphenylphosphine oxide can realize a superstructure or form a periodic, tightly stacked, interconnected structure through π-π conjugated self-assembly, thereby improving the passivation stability of the oxide nanoparticle surface, stabilizing the passivated oxide nanoparticle surface, and more effectively reducing its surface defects.

[0028] In some embodiments, the passivating agent is a triphenylphosphine oxide derivative, and the triphenylphosphine oxide derivative is One of the above, wherein R1, R2 and R3 are large π bond groups; the large π bond group is directly connected to the triphenylphosphine oxide, or the large π bond group is connected to the triphenylphosphine oxide through a group containing a π bond.

[0029] In this embodiment, the oxygen atoms in the phosphorus-oxygen double bonds of the triphenylphosphine oxide derivatives can interact with the hydroxyl groups on the surface of the oxide nanoparticles to form hydrogen bonds, thereby passivating the oxide nanoparticles. The triphenylphosphine oxide derivatives can also form superstructures or periodic, tightly packed, interconnected structures through π-π conjugated self-assembly, thereby improving the passivation stability of the oxide nanoparticle surfaces, stabilizing the passivated oxide nanoparticle surfaces, and more effectively reducing surface defects. When R1, R2, and R3 are large π-bond groups directly connected to the triphenylphosphine oxide, the large π-bond groups directly connected to the triphenylphosphine oxide can, on the one hand, avoid increasing the steric effect, thereby avoiding weakening the interaction between the phosphorus-oxygen double bond and the hydroxyl group. On the other hand, the large π-bond groups can also form conjugation with the π bonds on the triphenylphosphine oxide, thereby achieving a wider range of conjugation, expanding the conjugated area of ​​the triphenylphosphine oxide derivatives, and facilitating the formation of periodic, tightly packed, interconnected structures, thereby improving the stability of the passivated N-type oxide nanoparticles.

[0030] In some embodiments, R1, R2, and R3 are large π-bond groups, and the large π-bond groups are connected to the triphenylphosphine oxide via a group containing a π-bond. For example, the large π-bond group is connected to the triphenylphosphine oxide via a vinyl group or an acetylene group. The large π-bond group in this embodiment can also form conjugation with the π bond on the triphenylphosphine oxide, thereby achieving a wider range of conjugation, expanding the conjugated area of ​​the triphenylphosphine oxide derivative, and facilitating the formation of a periodic, tightly packed, interconnected structure, thereby improving the stability of the passivated N-type oxide nanoparticles.

[0031] In some embodiments, the large π bond group is one of a butadiene vinyl group or a benzene ring, but is not limited thereto. Specifically, in a molecule composed of multiple atoms, if there are p orbitals parallel to each other, they overlap coherently to form a whole, and p electrons move between multiple atoms to form a π-type chemical bond. This π bond that is not limited to between two atoms is called a delocalized π bond, or a conjugated large π bond, or simply a large π bond. A large π bond is a π bond formed by overlapping the p orbitals of 3 or more atoms parallel to each other from the side. Taking a benzene ring as an example, the molecular structure of a benzene ring is that six carbon atoms are combined into a regular hexagon in the same plane with sp2 hybrid orbitals. The remaining p orbitals that do not participate in hybridization on each carbon atom are parallel to the plane formed by the benzene molecule, so all p orbitals can overlap with each other; the large π bond of benzene is evenly distributed on six carbon atoms, so the bond length and bond energy of each carbon-carbon bond in the benzene molecule are equal. Taking 1,3-butadiene as an example, its four carbon atoms are adjacent to three atoms, so sp hybridization is adopted. These hybrid orbitals overlap with each other to form a molecular σ skeleton, so all atoms are in the same plane; each carbon atom also has a p orbital that does not participate in hybridization, perpendicular to the molecular plane, and each p orbital contains an electron, so there is a "4 orbitals 4 electrons" pp large π bond in the butadiene molecule.

[0032] In some embodiments, the group containing a π bond is a vinyl group or an acetylene group. Specifically, when the orbitals (p orbitals) of two atoms approach each other perpendicular to the internuclear line of the bonding atoms, the electron clouds overlap to form a bond, and the covalent bond formed in this way is called a π bond.

[0033] In some embodiments, the oxide nanoparticles are N-type oxide nanoparticles. For example, the N-type oxide nanoparticles are one or more of ZnO, TiO2, SnO2, Ta2O3, ZnMgO, ZnAlO, and SnInO, but are not limited thereto.

[0034] In some specific embodiments, the composite nanoparticles comprise ZnO with hydroxyl groups on their surfaces and triphenylphosphine oxide hydrogen-bonded with the hydroxyl groups. In this embodiment, the oxygen atoms in the triphenylphosphine oxide interact with the hydroxyl groups on the surface of the N-type oxide nanoparticles to form hydrogen bonds, and the triphenylphosphine oxide molecules self-assemble through π-π conjugation to form a superstructure, thereby improving passivation stability. This stabilizes the surface of the passivated N-type oxide nanoparticles, reduces surface defects, and eliminates dangling hydroxyl groups on the surface, thereby maintaining and effectively exerting the electron transport properties of the composite nanoparticles.

[0035] In some embodiments, a quantum dot light-emitting diode is also provided, which includes an electron transport layer, wherein the electron transport layer material is a composite nanoparticle, and the composite nanoparticle includes oxide nanoparticles containing hydroxyl groups on the surface and a passivator containing phosphorus-oxygen double bonds, and the hydroxyl groups on the surface of the oxide nanoparticles form hydrogen bonds with the phosphorus-oxygen double bonds in the passivator.

[0036] In this embodiment, the hydroxyl groups on the surface of the oxide nanoparticles in the composite nanoparticles can interact with the oxygen atoms in the phosphorus-oxygen double bonds in the passivating agent to form hydrogen bonds, thereby passivating the surface of the oxide nanoparticles and effectively reducing surface defects. The hydroxyl groups on the surface of the oxide nanoparticles participate in the hydrogen bonding, preventing the dangling hydroxyl groups from being oxidized to form highly oxidizing OH radicals under prolonged power-on conditions and the influence of the surrounding environment. This prevents the active OH radicals from oxidizing organic matter, thereby reducing the shedding of ligands on the quantum dot surface and effectively utilizing the electron transport properties of the oxide nanoparticles. Therefore, using the composite nanoparticles as the electron transport layer material for quantum dot light-emitting diodes can effectively improve the luminous efficiency and service life of quantum dot light-emitting diodes.

[0037] In some embodiments, a quantum dot light-emitting diode is also provided, which includes an electron transport layer, wherein the electron transport layer material is a composite nanoparticle, and the composite nanoparticle includes oxide nanoparticles containing hydroxyl groups on the surface and triphenylphosphine oxide, and the hydroxyl groups on the surface of the oxide nanoparticles form hydrogen bonds with the phosphorus-oxygen double bonds in the triphenylphosphine oxide.

[0038] In this embodiment, the oxygen atoms in the phosphorus-oxygen double bonds of the triphenylphosphine oxide interact with the hydroxyl groups on the surface of the oxide nanoparticles to form hydrogen bonds, thereby passivating the oxide nanoparticles. In addition, the triphenylphosphine oxide can realize a superstructure or form a periodic, tightly stacked, interconnected structure through π-π conjugated self-assembly, thereby improving the passivation stability of the oxide nanoparticle surface, stabilizing the passivated oxide nanoparticle surface, and more effectively reducing its surface defects. After the surface of the oxide nanoparticles is passivated, the suspended hydroxyl groups can be prevented from being oxidized to generate highly oxidizing OH radicals under long-term power-on conditions and the influence of the surrounding environment. This can prevent the active OH radicals from oxidizing organic matter, thereby reducing the shedding of ligands on the quantum dot surface, and effectively exerting the electron transport performance of the oxide nanoparticles. Therefore, using the composite nanoparticles as the electron transport layer material of the quantum dot light-emitting diode can effectively improve the luminous efficiency and service life of the quantum dot light-emitting diode.

[0039] In some embodiments, a quantum dot light-emitting diode is further provided, which includes an electron transport layer, wherein the electron transport layer material is a composite nanoparticle, wherein the composite nanoparticle includes oxide nanoparticles containing hydroxyl groups on the surface and a triphenylphosphine oxide derivative, wherein the hydroxyl groups on the surface of the oxide nanoparticles form hydrogen bonds with the phosphorus-oxygen double bonds in the triphenylphosphine oxide derivative, and the passivating agent is a triphenylphosphine oxide derivative. One of the above, wherein R1, R2 and R3 are large π bond groups; the large π bond group is directly connected to the triphenylphosphine oxide, or the large π bond group is connected to the triphenylphosphine oxide through a group containing a π bond.

[0040] In this embodiment, the oxygen atoms in the phosphorus-oxygen double bonds of the triphenylphosphine oxide derivative can interact with the hydroxyl groups on the surface of the oxide nanoparticles to form hydrogen bonds, thereby passivating the oxide nanoparticles. Furthermore, the triphenylphosphine oxide derivative can form a superstructure or a periodic, tightly packed, interconnected structure through π-π conjugation self-assembly, thereby improving the passivation stability of the oxide nanoparticle surface, stabilizing the passivated oxide nanoparticle surface, and more effectively reducing its surface defects. Furthermore, because R1, R2, and R3 are large π-bond groups directly connected to the triphenylphosphine oxide, on the one hand, they can avoid increasing the steric effect and thus preventing the weakening of the interaction between the phosphorus-oxygen double bond and the hydroxyl group. On the other hand, the large π-bond groups can also form conjugation with the π bond on the triphenylphosphine oxide, thereby achieving a wider range of conjugation, expanding the conjugated area of ​​the triphenylphosphine oxide derivative, and facilitating the formation of a periodic, tightly packed, interconnected structure, thereby improving its stability in passivating N-type oxide nanoparticles. After the oxide nanoparticles have undergone stable passivation, their surfaces can more effectively prevent the oxidation of suspended hydroxyl groups to form highly oxidizing OH radicals under prolonged power-on conditions and the influence of the surrounding environment. This prevents the active OH radicals from oxidizing organic matter, thereby reducing ligand shedding from the quantum dot surface and effectively utilizing the electron transport properties of the oxide nanoparticles. Therefore, using these composite nanoparticles as the electron transport layer material for quantum dot light-emitting diodes can effectively improve the luminous efficiency and service life of quantum dot light-emitting diodes.

[0041] In some embodiments, R1, R2, and R3 are large π-bond groups, and the large π-bond groups are connected to the triphenylphosphine oxide via a group containing a π-bond. For example, the large π-bond groups are connected to the triphenylphosphine oxide via a vinyl group. The large π-bond groups in this embodiment can also form conjugation with the π bond on the triphenylphosphine oxide, thereby achieving a wider range of conjugation, expanding the conjugated area of ​​the triphenylphosphine oxide derivative, and facilitating the formation of a periodic, tightly packed, interconnected structure, thereby improving the stability of the passivated N-type oxide nanoparticles.

[0042] In some specific embodiments, a quantum dot light-emitting diode is provided, comprising an electron transport layer (ETL), wherein the ETL material is ZnO having hydroxyl groups on its surface and triphenylphosphine oxide hydrogen-bonded with the hydroxyl groups. In this embodiment, the oxygen atoms in the triphenylphosphine oxide interact with the hydroxyl groups on the surface of the N-type oxide nanoparticles to form hydrogen bonds, and the triphenylphosphine oxide molecules form a superstructure through π-π conjugated self-assembly, thereby improving passivation stability, stabilizing the passivated N-type oxide nanoparticle surface, reducing surface defects, and eliminating hydroxyl groups suspended on the surface, thereby continuously and effectively exerting the electron transport performance of the ETL material.

[0043] In some embodiments, a quantum dot light-emitting diode is provided, which includes a cathode, an anode, and a quantum dot light-emitting layer arranged between the cathode and the anode, an electron transport layer is arranged between the cathode and the quantum dot light-emitting layer, and a hole functional layer is arranged between the anode and the quantum dot light-emitting layer, wherein the electron transport layer material is N-type oxide nanoparticles containing hydroxyl groups on the surface and triphenylphosphine oxide or a triphenylphosphine oxide derivative that forms a hydrogen bond with the hydroxyl groups, and the hole functional layer is one or more of an electron blocking layer, a hole injection layer, and a hole transport layer, but is not limited thereto.

[0044] In some specific embodiments, a positive-type quantum dot light-emitting diode is provided, such as Figure 1 As shown, it includes an anode arranged on the surface of a substrate, a hole injection layer arranged on the surface of the anode, a hole transport layer arranged on the surface of the hole injection layer, a quantum dot light-emitting layer arranged on the surface of the hole transport layer, an electron transport layer arranged on the surface of the quantum dot light-emitting layer and a cathode arranged on the surface of the electron transport layer, wherein the electron transport layer material is N-type oxide nanoparticles containing hydroxyl groups on the surface and triphenylphosphine oxide or a triphenylphosphine oxide derivative that forms a hydrogen bond with the hydroxyl groups.

[0045] In some embodiments, a quantum dot light emitting diode with an inversion structure is also provided, such as Figure 2As shown, it includes a cathode arranged on the surface of a substrate, an electron transport layer arranged on the surface of the cathode, a quantum dot light-emitting layer arranged on the surface of the electron transport layer, a hole transport layer arranged on the surface of the quantum dot light-emitting layer, a hole injection layer arranged on the surface of the hole transport layer and an anode arranged on the surface of the hole injection layer, wherein the electron transport layer material is N-type oxide nanoparticles containing hydroxyl groups on the surface and triphenylphosphine oxide or a triphenylphosphine oxide derivative that forms a hydrogen bond with the hydroxyl groups.

[0046] In various embodiments of the present invention, the materials of the functional layers are commonly used in the art, for example:

[0047] In some embodiments, the substrate may be a rigid substrate (glass) or a flexible substrate.

[0048] In some embodiments, the anode may be ITO, FTO, or ZTO.

[0049] In some embodiments, the hole injection layer material may be water-soluble PEDOT:PSS, or other materials with good hole injection properties, such as NiO, MoO3, WO3, or V2O5.

[0050] In some specific embodiments, the hole injection layer material is PEDOT:PSS, and its thickness is 10-100 nm.

[0051] In some embodiments, the hole transport layer material can be commonly used poly (9,9-dioctylfluorene-co-N-(4-butylphenyl) diphenylamine) (TFB), 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-carbazole)biphenyl (CBP), N,N'-diphenyl-N,N'-bis(3-methylphenyl)-1,1'-biphenyl-4,4'-diamine (TPD), N,N'-diphenyl-N,N'-(1-naphthyl)-1,1'-biphenyl-4,4'-diamine (NPB), or one or more of other high-performance hole transport materials, such as MoO3, WoO3, NiO, CuO, V2O5, CuS, etc.

[0052] In some specific embodiments, the hole transport layer has a thickness of 1-100 nm.

[0053] In some specific embodiments, the quantum dot light-emitting layer material can be one or more of common red light quantum dots, green light quantum dots and blue light quantum dots.

[0054] In some embodiments, the cathode can be Au, Ag, Al, Cu, Mo, or alloys thereof.

[0055] In some specific embodiments, the thickness of the cathode is 60-120 nm.

[0056] In some embodiments, a method for preparing a positive structure quantum dot light emitting diode is also provided, such as Figure 3 As shown, it includes the steps of:

[0057] S10, providing an anode substrate, and preparing a hole injection layer on the surface of the anode substrate;

[0058] S20, preparing a hole transport layer on the surface of the hole injection layer;

[0059] S30, preparing a quantum dot light-emitting layer on the surface of the hole transport layer;

[0060] S40, depositing a composite material solution on the surface of the quantum dot light-emitting layer to prepare an electron transport layer, wherein the composite material solution includes an organic alcohol, N-type oxide nanoparticles with hydroxyl groups on the surface dispersed in the organic alcohol, and triphenylphosphine oxide or a triphenylphosphine oxide derivative that forms a hydrogen bond with the hydroxyl groups, wherein the triphenylphosphine oxide derivative is One of the above, wherein R1, R2 and R3 are large π bond groups; the large π bond group is directly connected to the triphenylphosphine oxide, or the large π bond group is connected to the triphenylphosphine oxide through a group containing a π bond;

[0061] S50, preparing a cathode on the electron transport layer to obtain the quantum dot light emitting diode.

[0062] In each embodiment of the present invention, the preparation method of each layer can be a chemical method or a physical method, wherein the chemical method includes but is not limited to one or more of chemical vapor deposition, continuous ion layer adsorption and reaction, anodization, electrolytic deposition, and co-precipitation; the physical method includes but is not limited to one or more of solution method (such as spin coating, printing, doctor blade coating, dip pulling, immersion, spraying, roll coating, casting, slit coating or strip coating, etc.), evaporation method (such as thermal evaporation, electron beam evaporation, magnetron sputtering or multi-arc ion plating, etc.), deposition method (such as physical vapor deposition, atomic layer deposition, pulsed laser deposition, etc.).

[0063] In some embodiments, the composite material solution is prepared by adding triphenylphosphine oxide or a triphenylphosphine oxide derivative to an organic alcohol solution of N-type oxide nanoparticles containing surface hydroxyl groups, and performing ultrasonic dispersion to obtain the composite material solution. In this embodiment, the organic alcohol is one of ethanol, propanol, or butanol, but is not limited thereto; the mass fraction of the composite material solution is 0.1-10%.

[0064] In some specific embodiments, the thickness of the electron transport layer is 10-60 nm.

[0065] In some embodiments, a method for preparing an inversion structure quantum dot light emitting diode is also provided, such as Figure 4 As shown, it includes the steps of:

[0066] S100, providing a cathode substrate, depositing a composite material solution on the surface of the cathode substrate to prepare an electron transport layer, wherein the composite material solution includes an organic alcohol, N-type oxide nanoparticles with hydroxyl groups on the surface dispersed in the organic alcohol, and triphenylphosphine oxide or a triphenylphosphine oxide derivative that forms a hydrogen bond with the hydroxyl groups, wherein the triphenylphosphine oxide derivative is One of the above, wherein R1, R2 and R3 are large π bond groups; the large π bond group is directly connected to the triphenylphosphine oxide, or the large π bond group is connected to the triphenylphosphine oxide through a group containing a π bond;

[0067] S200, preparing a quantum dot light-emitting layer on the surface of the electron transport layer;

[0068] S300, preparing a hole transport layer on the surface of the quantum dot light-emitting layer;

[0069] S400, preparing a hole injection layer on the surface of the hole transport layer;

[0070] S500 , preparing an anode on the surface of the hole injection layer to obtain the quantum dot light emitting diode.

[0071] The following is a further explanation of the method for preparing a quantum dot light-emitting diode according to the present invention through specific examples:

[0072] Example 1

[0073] A method for preparing a positive-structure quantum dot light-emitting diode comprises the following steps:

[0074] First, the patterned ITO substrate was ultrasonically cleaned in acetone, detergent, deionized water, and isopropyl alcohol in sequence. Each ultrasonic step lasted about 15 minutes. After the ultrasonic cleaning was completed, the ITO was placed in a clean oven for drying. After the ITO substrate was dried, the ITO surface was treated with ultraviolet ozone for 5 minutes to further remove organic matter attached to the ITO surface and improve the work function of the ITO.

[0075] Then, a layer of PEDOT:PSS was spin-coated on the surface of the treated ITO substrate with a thickness of 20 nm. The substrate was placed on a hot plate at 150°C for 30 minutes to remove moisture. This step must be completed in air.

[0076] Next, the dried substrate coated with the hole injection layer was placed in a nitrogen atmosphere and a layer of hole transport layer material TFB was spin-coated to a thickness of 20 nm. The substrate was then heated on a heating plate at 150°C for 30 minutes to remove the solvent.

[0077] After the wafer treated in the previous step cools down, green quantum dot luminescent material is spin-coated on the surface of the hole transport layer to a thickness of 20nm. After this deposition step is completed, the wafer is placed on a heating table at 80℃ for 10 minutes to remove residual solvent;

[0078] Subsequently, 14 mg of triphenylphosphine oxide was added to 10 ml of an ethanol solution of ZnO nanoparticles with a concentration of 30 mg / ml, and then deposited on the quantum dot layer as an electron transport layer with a thickness of 30 nm. After deposition, the wafer was placed on a heating table at 80°C for 10 minutes to remove residual solvent.

[0079] Finally, the wafer after depositing each functional layer is placed in a vapor deposition chamber and a layer of aluminum is thermally evaporated through a mask plate as a cathode with a thickness of 100 nm. The device is then prepared to obtain the quantum dot light-emitting diode.

[0080] The efficiency and service life of the quantum dot light-emitting diode prepared in Example 1 were tested. Compared with ZnO nanoparticles as the electron transport layer, the external quantum efficiency did not change much, from 16.8% to 16.9%, and the device life T95@1000nits increased from 1100 hours to 2300 hours, a significant improvement.

[0081] Example 2

[0082] A method for preparing an inversion structure quantum dot light-emitting diode comprises the following steps:

[0083] First, the patterned ITO substrate was ultrasonically cleaned in acetone, detergent, deionized water, and isopropyl alcohol, sequentially. Each ultrasonic cleaning step lasted approximately 15 minutes. After the ultrasonic cleaning was complete, the ITO substrate was dried in a clean oven. After drying, the surface was treated with UV-ozone for 5 minutes to further remove organic matter adhering to the ITO surface.

[0084] Then, 28 mg of triphenylphosphine oxide was added to 10 ml of an ethanol solution of ZnO nanoparticles with a concentration of 30 mg / ml. After mixing evenly, the mixture was spin-coated on the ITO as an electron transport layer with a thickness of 25 nm. After deposition, the wafer was placed on a heating table at 80°C for 10 minutes to remove the residual solvent.

[0085] After the wafer cools, red quantum dot luminescent material is spin-coated onto the electron transport layer to a thickness of 20 nm. After this deposition step, the wafer is heated on a heating plate at 80°C for 10 minutes to remove any residual solvent.

[0086] Then, a layer of hole transport layer material NPB is evaporated, and the thickness of this layer is 10 nm.

[0087] Subsequently, a layer of hole injection layer material MoO3 is evaporated, and the thickness of this layer is 30nm.

[0088] Finally, the wafer after depositing each functional layer is placed in a vapor deposition chamber and a layer of silver is thermally evaporated through a mask plate as an anode with a thickness of 80 nm. The device is then prepared to obtain the quantum dot light-emitting diode.

[0089] The efficiency and service life of the quantum dot light-emitting diode prepared in Example 2 were tested. Compared with ZnO nanoparticles as the electron transport layer, the external quantum efficiency did not change much, from 18.1% to 19.2%, and the device life T95@1000nits increased from 4400 hours to 6500 hours, a significant improvement.

[0090] Example 3

[0091] A method for preparing a positive-structure quantum dot light-emitting diode comprises the following steps:

[0092] First, the patterned ITO substrate was ultrasonically cleaned in acetone, detergent, deionized water, and isopropyl alcohol in sequence. Each ultrasonic step lasted about 15 minutes. After the ultrasonic cleaning was completed, the ITO was placed in a clean oven for drying. After the ITO substrate was dried, the ITO surface was treated with ultraviolet ozone for 5 minutes to further remove organic matter attached to the ITO surface and improve the work function of the ITO.

[0093] Then, a layer of PEDOT:PSS was spin-coated on the surface of the treated ITO substrate with a thickness of 20 nm. The substrate was placed on a hot plate at 150°C for 30 minutes to remove moisture. This step must be completed in air.

[0094] Next, the dried substrate coated with the hole injection layer was placed in a nitrogen atmosphere, and a layer of hole transport layer material PFB was spin-coated to a thickness of 20 nm. The substrate was then placed on a heating plate at 150°C for 30 minutes to remove the solvent.

[0095] After the wafer treated in the previous step cools down, green quantum dot luminescent material is spin-coated on the surface of the hole transport layer to a thickness of 20nm. After this deposition step is completed, the wafer is placed on a heating table at 80℃ for 10 minutes to remove residual solvent;

[0096] Then, 18 mg of triphenylphosphine oxide derivative was added to 10 ml of ethanol solution of ZnO nanoparticles with a concentration of 30 mg / ml. Among them, R1 is a butadiene vinyl group, which is then deposited on the quantum dot layer as an electron transport layer with a thickness of 30 nm. After deposition, the wafer is placed on a heating table at 80°C and heated for 10 minutes to remove residual solvent.

[0097] Finally, the wafer after depositing each functional layer is placed in a vapor deposition chamber and a layer of aluminum is thermally evaporated through a mask plate as a cathode with a thickness of 100 nm. The device is then prepared to obtain the quantum dot light-emitting diode.

[0098] The efficiency and service life of the quantum dot light-emitting diode prepared in Example 3 were tested. Compared with ZnO nanoparticles as the electron transport layer, the external quantum efficiency did not change much, from 16.8% to 17.5%, and the device life T95@1000nits increased from 1200 hours to 3500 hours, a significant improvement.

[0099] Example 4

[0100] A method for preparing a positive-structure quantum dot light-emitting diode comprises the following steps:

[0101] First, the patterned ITO substrate was ultrasonically cleaned in acetone, detergent, deionized water, and isopropyl alcohol in sequence. Each ultrasonic step lasted about 15 minutes. After the ultrasonic cleaning was completed, the ITO was placed in a clean oven for drying. After the ITO substrate was dried, the ITO surface was treated with ultraviolet ozone for 5 minutes to further remove organic matter attached to the ITO surface and improve the work function of the ITO.

[0102] Then, a layer of PEDOT:PSS was spin-coated on the surface of the treated ITO substrate with a thickness of 20 nm. The substrate was placed on a hot plate at 150°C for 30 minutes to remove moisture. This step must be completed in air.

[0103] Next, the dried substrate coated with the hole injection layer was placed in a nitrogen atmosphere, and a layer of hole transport layer material PFB was spin-coated to a thickness of 20 nm. The substrate was then placed on a heating plate at 150°C for 30 minutes to remove the solvent.

[0104] After the wafer treated in the previous step cools down, green quantum dot luminescent material is spin-coated on the surface of the hole transport layer to a thickness of 20nm. After this deposition step is completed, the wafer is placed on a heating table at 80℃ for 10 minutes to remove residual solvent;

[0105] Subsequently, 18 mg of triphenylphosphine oxide derivative was added to 10 ml of ethanol solution of ZnO nanoparticles with a concentration of 30 mg / ml. Among them, R2 is a benzene ring, which is connected to the triphenylphosphine oxide through a vinyl group, and then deposited on the quantum dot layer as an electron transport layer with a thickness of 30nm. After the deposition is completed, the wafer is placed on a heating table at 80°C and heated for 10 minutes to remove the residual solvent.

[0106] Finally, the wafer after depositing each functional layer is placed in a vapor deposition chamber and a layer of aluminum is thermally evaporated through a mask plate as a cathode with a thickness of 100 nm. The device is then prepared to obtain the quantum dot light-emitting diode.

[0107] The efficiency and service life of the quantum dot light-emitting diode prepared in Example 4 were tested. Compared with ZnO nanoparticles as the electron transport layer, the external quantum efficiency did not change much, from 16.8% to 17.3%, and the device life T95@1000nits increased from 1200 hours to 3300 hours, a significant improvement.

[0108] In summary, the quantum dot light-emitting diode provided by the present invention includes an electron transport layer, wherein the electron transport layer material is an oxide nanoparticle containing hydroxyl groups on the surface and triphenylphosphine oxide or a triphenylphosphine oxide derivative that forms a hydrogen bond with the hydroxyl groups. The oxygen atoms in the phosphorus-oxygen double bonds of the triphenylphosphine oxide and its derivatives can easily interact with the hydroxyl groups on the surface of the oxide nanoparticles to form hydrogen bonds, thereby passivating the oxide nanoparticles, and triphenylphosphine oxide or its derivatives can realize a superstructure or form a periodic, tightly stacked, interconnected structure through π-π conjugated self-assembly, thereby improving the passivation stability, stabilizing the passivated oxide nanoparticle surface, reducing surface defects, and eliminating the hydroxyl groups hanging on the surface of the oxide nanoparticles, thereby avoiding the oxidation of the hanging hydroxyl groups to generate highly oxidizing OH radicals, thereby reducing the shedding of ligands on the quantum dot surface and effectively exerting the electron transport performance of the electron transport material, thereby greatly improving the luminous efficiency and service life of the quantum dot light-emitting diode.

[0109] It should be understood that the application of the present invention is not limited to the above examples. For those skilled in the art, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A composite nanoparticle, characterized in that: The invention comprises oxide nanoparticles containing hydroxyl groups on the surface and a passivating agent containing a phosphorus-oxygen double bond, wherein the hydroxyl groups on the surface of the oxide nanoparticles form hydrogen bonds with the phosphorus-oxygen double bond in the passivating agent; the passivating agent is a triphenylphosphine oxide derivative, and the triphenylphosphine oxide derivative is , , , or One of the above, wherein R1, R2 and R3 are large π bond groups; the large π bond group is directly connected to the triphenylphosphine oxide, or the large π bond group is connected to the triphenylphosphine oxide through a group containing a π bond.

2. The composite nanoparticles according to claim 1, characterized in that The large π bond group is one of a benzene ring or a butadiene vinyl group; and / or the group containing a π bond is one of a vinyl group or an acetylene group.

3. The composite nanoparticles according to claim 1, characterized in that The oxide nanoparticles are one or more of ZnO, TiO2, SnO2, Ta2O3, ZnMgO, ZnAlO and SnInO.

4. A quantum dot light-emitting diode, characterized in that: It comprises an electron transport layer, wherein the material of the electron transport layer is the composite nanoparticles according to any one of claims 1 to 3.

5. The quantum dot light emitting diode according to claim 4, characterized in that: The invention also includes a cathode, an anode and a quantum dot light-emitting layer arranged between the cathode and the anode, and the electron transport layer is arranged between the cathode and the quantum dot light-emitting layer.

6. A method for preparing a quantum dot light-emitting diode, characterized in that: Including steps: providing a substrate; A composite nanoparticle solution is deposited on the substrate to prepare an electron transport layer, wherein the composite nanoparticle solution comprises organic alcohol and the composite nanoparticles according to any one of claims 1 to 3 dispersed in the organic alcohol.

7. The method for preparing a quantum dot light-emitting diode according to claim 6, wherein: The mass fraction of the composite nanoparticle solution is 0.1-10%.

Images