Quantum dot light-emitting diode and preparation method thereof

Abstract

The embodiment of the present application discloses a method for preparing a quantum dot light-emitting diode, comprising the following steps: providing a substrate and forming a bottom electrode on the substrate; providing an interface modification material, an electron transport material and an organic solvent, mixing them to obtain a mixed solution; providing a quantum dot material, disposing the quantum dot material on the bottom electrode to form a quantum dot film, and then disposing the mixed solution on the surface of the quantum dot film, drying to obtain a quantum dot light-emitting layer and an electron transport layer, wherein the quantum dot film is a quantum dot dry film or a quantum dot wet film; and forming a top electrode on the electron transport layer. The preparation method can change the contact mode between the quantum dots and the electron transport material from conventional point contact to surface contact, which can effectively increase the effective contact area between the quantum dot light-emitting layer and the electron transport layer, and promote electron transport between the quantum dot light-emitting layer and the electron transport layer. The present application also provides a quantum dot light-emitting diode prepared by the preparation method.

Description

Technical Field

[0001] The present application relates to the field of display technology, and in particular to a method for preparing a quantum dot light-emitting diode and a quantum dot light-emitting diode prepared using the method. Background Art

[0002] QLED (Quantum Dots Light-Emitting Diode) is an emerging display device with a structure similar to OLED (Organic Light-Emitting Diode). It is a new technology between liquid crystal and OLED. The core of QLED technology is quantum dots. Quantum dots are particles with a diameter of less than 10nm, mainly composed of zinc, cadmium, sulfur, and selenium atoms. When quantum dots are photoelectrically stimulated, they emit colored light. The color of the light is determined by the material that makes up the quantum dots and the size and shape of the quantum dots. The unique quantum size effect, macroscopic quantum tunneling effect, quantum size effect and surface effect of quantum dots enable them to exhibit excellent physical properties, especially optical properties, such as tunable spectrum, high luminous intensity, high color purity, long fluorescence lifetime, and the ability of a single light source to excite multi-color fluorescence.

[0003] Currently, the luminous efficiency of QLEDs has essentially reached commercialization requirements. Furthermore, QLEDs have a long lifespan and simple or no packaging is required, making them promising candidates for the next generation of flat-panel displays. However, the actual operating lifespan of currently manufactured quantum dot light-emitting diodes falls far short of their theoretical lifetime, and fluorescence quenching often occurs during testing. This significantly restricts the development of quantum dot light-emitting devices. The primary reason for this problem is the imbalance in the transmission rates of hole and electron carriers in quantum dot light-emitting diodes, which results in quantum dot charging and fluorescence quenching. Summary of the Invention

[0004] The embodiments of the present application provide a method for preparing a quantum dot light-emitting diode, which aims to improve the problem caused by the imbalance in the transmission rates of hole carriers and electron carriers in the quantum dot light-emitting diode.

[0005] The present invention provides a method for preparing a quantum dot light-emitting diode, which comprises the following steps:

[0006] providing a substrate, and forming a bottom electrode on the substrate;

[0007] Providing an interface modification material, an electron transport material and an organic solvent, mixing them to obtain a mixed solution;

[0008] Providing a quantum dot material, disposing the quantum dot material on a bottom electrode to form a quantum dot film, then disposing the mixed solution on the surface of the quantum dot film, and drying to obtain a quantum dot light-emitting layer and an electron transport layer, wherein the quantum dot film is a quantum dot dry film or a quantum dot wet film;

[0009] A top electrode is formed on the electron transport layer.

[0010] Optionally, in some embodiments of the present application, a transition layer is formed between the quantum dot light-emitting layer and the electron transport layer, and the transition layer contains quantum dots, interface modification materials and electron transport materials. The interface modification materials in the transition layer fill the gaps between the quantum dots in the transition layer, the gaps between the electron transport materials, and the gaps between the quantum dots and the electron transport materials.

[0011] Optionally, in some embodiments of the present application, after the mixed solution is disposed on the surface of the quantum dot film, a step of standing is further included, and the standing time is 5-10 seconds.

[0012] Optionally, in some embodiments of the present application, the interface modification material is selected from one or more of polyethyleneimine, polyethoxyethyleneimine, poly[9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene]-2,7-(9,9-dioctylfluorene))], polyethylene glycol, conjugated polyelectrolyte or polyethylene oxide; and / or

[0013] The electron transport material is selected from one or more of metal oxides, doped metal oxides, Group 2-6 semiconductor materials, Group 3-5 semiconductor materials and Group 1-3-6 semiconductor materials, the metal oxide is selected from one or more of ZnO, TiO2 and SnO2; the metal oxide in the doped metal oxide is selected from one or more of ZnO, TiO2 and SnO2, and the doping element is selected from one or more of aluminum, magnesium, indium and gallium; the Group 2-6 semiconductor materials are selected from one or more of ZnS, ZnSe and CdS; the Group 3-5 semiconductor materials are selected from at least one of InP and GaP; the Group 1-3-6 semiconductor materials are selected from at least one of CuInS and CuGaS; and / or

[0014] The organic solvent is selected from one or more of ethylene glycol monomethyl ether, isopropyl alcohol or ethanol.

[0015] Optionally, in some embodiments of the present application, in the mixed solution, the concentration range of the interface modification material is 0.1 wt%-10 wt%, and the concentration range of the electron transport material is 10-30 mg / mL.

[0016] Correspondingly, an embodiment of the present application also provides a quantum dot light-emitting diode, which includes a stacked bottom electrode, a quantum dot light-emitting layer, an electron transport layer and a top electrode, wherein the quantum dot light-emitting layer contains quantum dots, the electron transport layer contains electron transport material, and the gaps between adjacent quantum dots and electron transport materials are filled with interface modification materials.

[0017] Optionally, in some embodiments of the present application, the interface modification material is also filled in the gaps between the quantum dots on the side of the quantum dot light-emitting layer adjacent to the electron transport layer, and in the gaps between the electron transport materials of the electron transport layer.

[0018] Optionally, in some embodiments of the present application, the quantum dot light-emitting diode further includes a transition layer located between the quantum dot light-emitting layer and the electron transport layer, the transition layer containing quantum dots, interface modification materials and electron transport materials, and the interface modification materials in the transition layer fill the gaps between the quantum dots in the transition layer, the gaps between the electron transport materials, and the gaps between the quantum dots and the electron transport materials.

[0019] Optionally, in some embodiments of the present application, the interface modification material is also filled between the quantum dot light-emitting layer and the transition layer, and between the transition layer and the electron transport layer.

[0020] Optionally, in some embodiments of the present application, the interface modification material is selected from one or more of polyethyleneimine, polyethoxyethyleneimine, poly[9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene]-2,7-(9,9-dioctylfluorene))], polyethylene glycol, conjugated polyelectrolyte or polyethylene oxide;

[0021] The electron transport material is selected from one or more of metal oxides, doped metal oxides, Group 2-6 semiconductor materials, Group 3-5 semiconductor materials and Group 1-3-6 semiconductor materials, the metal oxide is selected from one or more of ZnO, TiO2, and SnO2; the metal oxide in the doped metal oxide is selected from one or more of ZnO, TiO2, and SnO2, and the doping element is selected from one or more of aluminum, magnesium, indium, and gallium; the Group 2-6 semiconductor material is selected from one or more of ZnS, ZnSe, and CdS; the Group 3-5 semiconductor material is selected from at least one of InP and GaP; the Group 1-3-6 semiconductor material is selected from at least one of CuInS and CuGaS.

[0022] Compared with the prior art, this application has the following advantages:

[0023] The preparation method of the quantum dot light-emitting diode of the present application first mixes the interface modification material with the electron transport material and the organic solvent to obtain a mixed solution, and then when the mixed solution is set on the surface of the quantum dot light-emitting layer, the interface modification material will penetrate into the gaps between the quantum dots along with the organic solvent. In this way, the interface modification material of the prepared quantum dot light-emitting diode is filled in the gaps between the quantum dots of the quantum dot light-emitting layer, in the gaps between the electron transport materials of the electron transport layer, and in the gaps between adjacent quantum dots and electron transport materials. In this way, the contact mode between the quantum dots and the electron transport materials is changed from conventional point contact to surface contact, which can effectively increase the effective contact area between the quantum dot light-emitting layer and the electron transport layer, promote electron transport between the quantum dot light-emitting layer and the electron transport layer, reduce or even avoid the problem of imbalance in the transmission rate of hole carriers and electron carriers, and thus avoid the phenomenon of quantum dot charging and fluorescence quenching.

[0024] The preparation method of the quantum dot light-emitting diode of the present application first mixes the interface modification material with the electron transport material and the organic solvent to obtain a mixed solution, and then sets the mixed solution on the surface of the quantum dot wet film. In this way, the interface modification material will penetrate into the gaps between the quantum dots along with the organic solvent, and the quantum dots and the electron transport material on the surface of the quantum dot wet film will be mixed due to factors such as gravity, which can further increase the effective contact area between the quantum dot light-emitting layer and the electron transport layer, and promote electron transport between the quantum dot light-emitting layer and the electron transport layer.

[0025] The interface modification material used in the preparation method of the quantum dot light-emitting diode of the present application has the effect of reducing the work function of the material and passivating the surface defects of the material. When it penetrates into the interface between the quantum dots and the electron transport material, it has a regulating effect on the material interface, which can reduce the interface barrier of the material, thereby promoting the transmission of charge. In addition, since the particle size of the quantum dots and the electron transport material is small and both are nanostructured, the specific surface area of ​​the material is large and the surface defect content is high, this will have a strong capture effect on the free charge, thereby causing non-fluorescent recombination and poor device performance. However, under the coating effect of the interface modification material, the surface defects of the nanoparticles will be passivated, which can reduce non-fluorescent recombination and improve device performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 This is a flow chart of a method for preparing a quantum dot light-emitting diode provided in an embodiment of the present application;

[0028] Figure 2 is a schematic diagram of a quantum dot light-emitting diode provided in an embodiment of the present application;

[0029] Figure 3 is a schematic diagram of another quantum dot light-emitting diode provided in an embodiment of the present application;

[0030] Figure 4 is a graph showing the change in current density versus voltage of the quantum dot light-emitting diodes of Example 1 and Comparative Example 1 of the present application;

[0031] Figure 5 is a graph showing the change in brightness of the quantum dot light-emitting diodes of Example 1 and Comparative Example 1 of the present application as a function of voltage;

[0032] Figure 6 1 is an external quantum efficiency-voltage curve of the quantum dot light-emitting diodes of Example 1 and Comparative Example 1 of the present application;

[0033] Figure 7 1 is a current efficiency-voltage curve of the quantum dot light-emitting diodes of Example 1 and Comparative Example 1 of the present application;

[0034] Figure 8 1 is a brightness-time curve diagram of the quantum dot light-emitting diodes of Example 1 and Comparative Example 1 of the present application;

[0035] Figure 9 This is a life curve diagram of the quantum dot light-emitting diode of Example 1 extrapolated by an empirical formula of the present application. DETAILED DESCRIPTION

[0036] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making creative efforts are within the scope of protection of this application.

[0037] The embodiments of the present application provide a method for preparing a quantum dot light-emitting diode. The following are detailed descriptions. It should be noted that the order of description of the following embodiments does not limit the preferred order of the embodiments. In addition, in the description of this application, the term "including" means "including but not limited to". Various embodiments of the present invention may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the invention; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the numbered range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated in this article, it is meant to include any cited number (fraction or integer) within the indicated range.

[0038] See also Figure 1-3 An embodiment of the present application provides a method for preparing a quantum dot light-emitting diode 100, which includes the following steps:

[0039] Step S1: providing a substrate 1, and forming a bottom electrode 2 on the substrate 1;

[0040] Step S2: providing an interface modification material 3, an electron transport material 51, and an organic solvent, and mixing them to dissolve the interface modification material 3 in the organic solvent and disperse the electron transport material 51 in the organic solvent to obtain a mixed solution;

[0041] Step S3: providing a quantum dot material, disposing the quantum dot material on the bottom electrode 2 to form a quantum dot film, and then disposing the mixed solution on the surface of the quantum dot film by a solution method, forming a film, and drying to obtain a quantum dot light-emitting layer 4 and an electron transport layer 5 combined with the quantum dot light-emitting layer 4;

[0042] Step S4: forming a top electrode 6 on the electron transport layer 5 .

[0043] In step S3, the method for setting the quantum dot material on the bottom electrode 2 can be a chemical film forming method or a physical film forming method known in the art. The chemical film forming method includes: chemical vapor deposition, continuous ion layer adsorption and reaction, anodic oxidation, electrolytic deposition, and co-precipitation. The physical film forming method includes physical plating and solution processing. Specifically, the physical plating method includes: thermal evaporation coating, electron beam evaporation coating, magnetron sputtering, multi-arc ion plating, physical vapor deposition, atomic layer deposition, pulsed laser deposition, etc.; the solution processing method includes spin coating, printing, inkjet printing, doctor blade coating, printing, dip-coating, immersion, spraying, roller coating, casting, slit coating, and strip coating.

[0044] The quantum dot film can be a dried quantum dot dry film or an undried quantum dot wet film, wherein the quantum dot dry film is the quantum dot light-emitting layer 4 .

[0045] See also Figure 2 In one embodiment, the step S3 is S03: providing a quantum dot material, disposing the quantum dot material on the bottom electrode 2 to form a quantum dot dry film, and obtaining a quantum dot light-emitting layer 4; then, adding the mixed solution to the quantum dot light-emitting layer 4, allowing the interface modification material 3 to penetrate at least into the gaps between the quantum dots 41 on the side of the quantum dot light-emitting layer 4 adjacent to the electron transport layer 5 along with the organic solvent; forming a film, and drying to obtain the electron transport layer 5. The interface modification material 3 fills the gaps between the quantum dots 41 of the quantum dot light-emitting layer 4, the gaps between the electron transport materials 51 of the electron transport layer 5, and the gaps between adjacent quantum dots 41 and electron transport materials 51. In this way, the contact mode between the quantum dots 41 and the electron transport material 51 is changed from conventional point contact to surface contact, which can effectively increase the effective contact area between the quantum dot light-emitting layer 4 and the electron transport layer 5, promote electron transport between the quantum dot light-emitting layer 4 and the electron transport layer 5, reduce or even avoid the problem of imbalance in the transmission rate of hole carriers and electron carriers, and thus avoid the phenomenon of charging of the quantum dots 41 and fluorescence quenching.

[0046] In at least one embodiment, an interface modification material 3 is filled between the quantum dot light-emitting layer 4 and the electron transport layer 5 .

[0047] See also Figure 3In another embodiment, step S3 is S13: providing a quantum dot material, disposing the quantum dot material on the bottom electrode 2 to form a quantum dot wet film, and then disposing the mixed solution on the surface of the quantum dot wet film by a solution method, so that the quantum dots on the surface of the quantum dot wet film are mixed with the electron transport material, and drying after film formation to obtain a quantum dot light-emitting layer 4, a transition layer 10 bonded to the quantum dot light-emitting layer 4, and an electron transport layer 5 bonded to the transition layer 10. The transition layer 10 contains quantum dots 41, an interface modification material 3, and an electron transport material 51. The interface modification material 3 in the transition layer 10 fills the gaps between the quantum dots 41 in the transition layer 10, the gaps between the electron transport materials 51, and the gaps between the quantum dots 41 and the electron transport material 51. In other words, the quantum dots 41 and the electron transport material 51 in the transition layer 10 are randomly embedded in the interface modification material 3. The interface modification material 3 is also filled in the gaps between the quantum dot light-emitting layer 4 and the transition layer 10, between the transition layer 10 and the electron transport layer 5, between the quantum dots 41 of the quantum dot light-emitting layer 4, and between the electron transport materials 51 of the electron transport layer 5. The mixed solution is disposed on the surface of the quantum dot wet film by a solution method, so that the quantum dots 41 and the electron transport material 51 on the surface of the quantum dot wet film can be mixed, thereby obtaining a transition layer in which the quantum dots 41 and the electron transport material 51 are mixed. This can further increase the effective contact area between the quantum dot light-emitting layer 4 and the electron transport layer 5, thereby promoting electron transport between the quantum dot light-emitting layer 4 and the electron transport layer 5.

[0048] In a preferred embodiment, the step S13 comprises providing a quantum dot material, spin-coating the quantum dot material on the bottom electrode 2 to form a quantum dot wet film, adding the mixed solution within a few seconds after the start of spin coating, stopping the spin coating after the addition is completed, and drying the film after film formation to obtain a quantum dot light-emitting layer 4, a transition layer 10 bonded to the quantum dot light-emitting layer 4, and an electron transport layer 5 bonded to the transition layer 10. By dropwise adding the mixed solution within a few seconds after the start of spin coating of the quantum dot material, the interface modification material 3 will penetrate into the gaps between the quantum dots of the quantum dot wet film along with the organic solvent, and during the spin coating process, the quantum dots on the surface of the quantum dot wet film and the electron transport material can be better mixed with each other.

[0049] It can be understood that, in one embodiment, the gaps between all quantum dots in the quantum dot light-emitting layer 4 are filled with the interface modification material 3. In another embodiment, the gaps between the quantum dots 41 in the region of the quantum dot light-emitting layer 4 adjacent to the electron transport layer 5 are filled with the interface modification material 3, while the gaps between the quantum dots 41 in the region away from the electron transport layer 5 are not filled with the interface modification material 3.

[0050] The drying method is a method known in the art for drying quantum dot films, such as baking.

[0051] In step S1, the choice of substrate 1 is not limited, and a flexible substrate or a rigid substrate can be selected. The method for forming the bottom electrode 2 on the substrate 1 is a conventional method in the art, such as evaporation. The bottom electrode 2 is an anode. The anode is an anode commonly used in the art. In at least one embodiment, the anode 2 is ITO (tin-indium oxide).

[0052] In the step S2, the interface modification material has a permanent dipole moment. The interface modification material can be selected from but not limited to PEI (polyethyleneimine), PEIE (polyethoxyethyleneimine), PFN (poly [9,9-bis (3'- (N, N-dimethylamino) propyl) -2,7-fluorene] -2,7- (9,9-dioctylfluorene))]), PEG (polyethylene glycol), CPE (conjugated polyelectrolyte), PEO (polyethylene oxide) one or more. The interface modification material 3 has the effect of reducing the work function of the material and passivating the surface defects of the material. When it penetrates into the interface of the quantum dots 41 and the electron transport material 51, it has a regulating effect on the material interface, can reduce the interface barrier of the material, thereby promoting the transmission of charge. In addition, since the particle size of the quantum dots 41 and the electron transport material 51 is small and both are nanostructured, the specific surface area of ​​the material is large and the surface defect content is high, this will have a strong capture effect on the free charge, thereby causing non-fluorescent recombination, resulting in poor device performance. However, under the coating effect of the interface modification material 3, the surface defects of the nanoparticles will be passivated, which can reduce non-fluorescent recombination and improve device performance.

[0053] In the mixed solution, the concentration of the interface modification material 3 is preferably in the range of 0.1 wt% to 10 wt%. At this concentration, the viscosity of the mixed solution is moderate, allowing the interface modification material 3 to effectively penetrate the gaps between the quantum dots 41 of the quantum dot light-emitting layer 4. Excessively high concentrations significantly increase the viscosity of the mixed solution, making it more difficult for the interface modification material 3 to penetrate the gaps between the quantum dots 41, and increasing the thickness of the interface modification material between the quantum dot light-emitting layer 4 and the electron transport layer 5, thereby increasing the resistance to charge transfer.

[0054] In the mixed solution, the concentration of the electron transport material 51 is in the range of 10-30 mg / mL. The electron transport material 51 is a material commonly used in the art for electron transport. The electron transport material 51 is selected from, but not limited to, one or more of metal oxides, doped metal oxides, Group 2-6 semiconductor materials, Group 3-5 semiconductor materials, and Group 1-3-6 semiconductor materials. Specifically, the metal oxide is selected from, but not limited to, one or more of zinc oxide (ZnO), titanium oxide (TiO2), and tin oxide (SnO2); the metal oxide in the doped metal oxide is selected from, but not limited to, at least one of ZnO, TiO2, and SnO2, and the doping element is selected from, but not limited to, one or more of aluminum, magnesium, indium, and gallium; the Group 2-6 semiconductor material is selected from, but not limited to, one or more of ZnS, ZnSe, and CdS; the Group 3-5 semiconductor material is selected from, but not limited to, at least one of InP and GaP; and the Group 1-3-6 semiconductor material is selected from, but not limited to, at least one of CuInS and CuGaS. Preferably, the electron transport material 51 is nano-ZnO, nano-TiO or nano-SnO 2. More preferably, the particle size of the nano-ZnO is less than 20 nm.

[0055] The organic solvent is a solvent commonly used in the art. The organic solvent is a high-viscosity solvent or a low-viscosity solvent. The high-viscosity solvent can be ethylene glycol monomethyl ether (EGME, viscosity 1.7 mPa·s), isopropyl alcohol (viscosity 2.4 mPa·s), etc. The low-viscosity solvent can be ethanol (viscosity 1.2 mPa·s), etc. Preferably, the organic solvent is a low-viscosity solvent, which is conducive to the penetration of the interface modification material 3 into the gaps between the quantum dots 41.

[0056] In step S3, the quantum dot material is a conventionally used quantum dot material in the art, such as CdSeZnS, CdSeCdS / ZnS, or ZnCdS / ZnS. The concentration of the quantum dots in the quantum dot material is 10-20 mg / mL. The baking temperature is 80-120° C., and the baking time is 5-30 minutes.

[0057] In step S03, after adding the mixed solution to the quantum dot light-emitting layer 4, a further step of standing is included to allow the interface modification material 3 to fully penetrate the gaps between the quantum dots 41 on the side of the quantum dot light-emitting layer 4 adjacent to the electron transport layer 5. The standing time is preferably 5-10 seconds. The method for forming the quantum dot light-emitting layer 4 is preferably spin coating, with a spin coating speed range of 2000-3000 r / s and a time range of 20-30 seconds.

[0058] In step S13, when the quantum dot material is spin-coated on the bottom electrode 2, the spin-coating speed is 2000-3000 r / s and the time is 25-35 seconds. The mixed solution is added dropwise within 2-10 seconds after the start of spin-coating.

[0059] In step S4, the method for forming the top electrode 6 on the electron transport layer 5 is a conventional method in the art, such as evaporation. The top electrode 6 is a cathode, and the cathode is a cathode conventionally used in the art, such as Al, Ag, Al / Ag, Cu, Au, and alloy electrodes. In at least one embodiment, the evaporation method is: by thermal evaporation, with a vacuum degree of no more than 3x10 - 4 Pa, evaporate at a rate of 0.5-1 angstrom / second for 1000-2000 seconds.

[0060] It is understood that before forming the quantum dot light-emitting layer 4 on the bottom electrode 2, the process also includes forming at least one of a hole transport layer and a hole injection layer on the bottom electrode 2. The methods for forming the hole transport layer and the hole injection layer are conventional methods in the art, such as evaporation.

[0061] In at least one embodiment, the method for forming the hole injection layer is: spin coating the hole injection layer material on the bottom electrode 2, and then baking. The spin coating speed is 4000-5000 r / s, and the time is 30 seconds. The baking temperature is 150°C, and the time is 15-30 minutes. The hole injection layer material is a material conventionally used in the field for hole injection layers, such as a mixed material of PEDOT (polymer of (3,4-ethylenedioxythiophene monomer)): PSS (sodium polystyrene sulfonate).

[0062] In at least one embodiment, the hole transport layer is formed by spin-coating a hole transport layer material onto the bottom electrode 2 or the hole injection layer, followed by baking. The spin coating is performed at a speed of 3000 r / s for 30 seconds. The baking temperature is 80° C. for 10-30 minutes. The hole transport layer material is a material commonly used in the art for hole transport layers, such as TFB (nickel etchant).

[0063] It can be understood that before forming the top electrode 6 on the electron transport layer 5 , a step of forming an electron injection layer on the electron transport layer 5 may be further included.

[0064] An embodiment of the present invention further provides a quantum dot light-emitting diode 100, comprising a substrate 1, a bottom electrode 2, a quantum dot light-emitting layer 4, an electron transport layer 5, and a top electrode 6, which are stacked in sequence. The quantum dot light-emitting layer 4 includes quantum dots 41, and the electron transport layer 5 includes an electron transport material 51. The quantum dot light-emitting diode 100 further includes an interface modification material 3. The interface modification material 3 fills the gaps between the quantum dots 41 in the quantum dot light-emitting layer 4, the gaps between the electron transport materials 51 in the electron transport layer 5, and the gaps between adjacent quantum dots 41 and electron transport materials 51.

[0065] In at least one embodiment, an interface modification material 3 is filled between the quantum dot light-emitting layer 4 and the electron transport layer 5 .

[0066] In one embodiment, the gaps between all quantum dots 41 of the quantum dot light-emitting layer 4 are filled with the interface modification material 3. In another embodiment, the gaps between the quantum dots 41 in the region of the quantum dot light-emitting layer 4 adjacent to the electron transport layer 5 are filled with the interface modification material 3, while the gaps between the quantum dots 41 in the region of the quantum dot light-emitting layer 4 away from the electron transport layer 5 are not filled with the interface modification material 3.

[0067] In one embodiment, the quantum dot light-emitting diode 100 further includes a hole transport layer and a hole injection layer sequentially stacked on the bottom electrode 2 .

[0068] It can be understood that the quantum dot light-emitting diode 100 further includes an electron injection layer located between the electron transport layer 5 and the top electrode 6 .

[0069] The embodiment of the present invention also provides another quantum dot light-emitting diode 100, which includes a substrate 1, a bottom electrode 2, a quantum dot light-emitting layer 4, a transition layer 10, an electron transport layer 5, and a top electrode 6, which are stacked in sequence. The quantum dot light-emitting layer 4 contains quantum dots 41, and the electron transport layer 5 contains an electron transport material 51. The quantum dot light-emitting diode 100 also includes an interface modification material 3. The transition layer 10 contains quantum dots 41, electron transport material 51, and interface modification material 3. The gaps between the quantum dots 41 in the transition layer 10, the gaps between the electron transport materials 51, and the gaps between the quantum dots 41 and the electron transport material 51 are filled with the interface modification material 3. In other words, the quantum dots 41 and the electron transport material 51 in the transition layer 10 are randomly embedded in the interface modification material 3. The interface modification material 3 is also filled in the gaps between the quantum dot light-emitting layer 4 and the transition layer 10 , between the transition layer 10 and the electron transport layer 5 , between the quantum dots 41 of the quantum dot light-emitting layer 4 , and between the electron transport materials 51 of the electron transport layer 5 .

[0070] In one embodiment, the gaps between all quantum dots 41 of the quantum dot light-emitting layer 4 are filled with the interface modification material 3. In another embodiment, the gaps between the quantum dots 41 in the region of the quantum dot light-emitting layer 4 adjacent to the transition layer 10 are filled with the interface modification material 3, while the gaps between the quantum dots 41 in the region of the quantum dot light-emitting layer 4 away from the transition layer 10 are not filled with the interface modification material 3.

[0071] In one embodiment, the quantum dot light-emitting diode 100 further includes a hole transport layer and a hole injection layer sequentially stacked on the bottom electrode 2 .

[0072] It can be understood that the quantum dot light-emitting diode 100 further includes an electron injection layer located between the electron transport layer 5 and the top electrode 6 .

[0073] The present invention will be described in detail below through specific examples. The following examples are only some implementation methods of the present invention and are not intended to limit the present invention.

[0074] Example 1

[0075] Preparation of quantum dot light-emitting diodes 100

[0076] Providing a substrate 1 with an ITO bottom electrode 2 bonded to its surface;

[0077] Print the PEDOT:PSS hybrid material on the ITO bottom electrode 2 and bake it at 150°C for 15 minutes to obtain the hole injection layer;

[0078] Printing TFB with a concentration of 8 mg / mL on the hole injection layer, and then baking at 80° C. for 10 min to obtain a hole transport layer;

[0079] Providing an interface modification material PEI, an electron transport material nano ZnO and an organic solvent ethylene glycol monomethyl ether, adding PEI and nano ZnO to the ethylene glycol monomethyl ether and mixing them evenly to obtain a PEI: nano ZnO mixed solution, wherein the concentration of PEI is 0.1 wt%;

[0080] Printing a quantum dot material with a concentration of 20 mg / mL on the surface of the hole transport layer to obtain a quantum dot light-emitting layer 4;

[0081] Printing the mixed solution on the quantum dot light-emitting layer 4, letting it stand for 5 seconds, and then baking it at 80° C. for 5 minutes to obtain the electron transport layer 5;

[0082] At a vacuum degree of 3x10 -4 Pa, an Al electrode was evaporated at a rate of 1 Å / s for 100 seconds, with an Al thickness of 10 nm;

[0083] At a vacuum degree of 3x10 -4 Under the condition of Pa, an Ag electrode was evaporated at a rate of 1 angstrom / second for 200 seconds, and the thickness of Ag was 20 nm, thereby obtaining a quantum dot light-emitting diode 100.

[0084] The interface modification material 3 of the quantum dot light-emitting diode 100 of this embodiment is filled in the gaps between the quantum dot light-emitting layer 4 and the electron transport layer 5, in the gaps between the quantum dots 41 in the area of ​​the quantum dot light-emitting layer 4 adjacent to the electron transport layer 5, and in the gaps between the electron transport materials 51 of the electron transport layer 5.

[0085] Example 2

[0086] Preparation of quantum dot light-emitting diodes 100

[0087] Providing a substrate 1 with an ITO bottom electrode 2 bonded to its surface;

[0088] Print the PEDOT:PSS hybrid material on the ITO bottom electrode 2 and bake it at 150°C for 15 minutes to obtain the hole injection layer;

[0089] Printing TFB with a concentration of 8 mg / mL on the hole injection layer, and then baking at 80° C. for 10 min to obtain a hole transport layer;

[0090] Providing an interface modification material PEI, an electron transport material nano ZnO and an organic solvent ethylene glycol monomethyl ether, adding PEI and nano ZnO to the ethylene glycol monomethyl ether and mixing them evenly to obtain a PEI: nano ZnO mixed solution, wherein the concentration of PEI is 0.1 wt%;

[0091] Spin coating a quantum dot material with a concentration of 20 mg / mL on the surface of the hole transport layer at a rotation speed of 2000 r / s for 30 seconds to obtain a quantum dot light-emitting layer 4;

[0092] The mixed solution was dropped onto the quantum dot light-emitting layer 4 and allowed to stand for 5 seconds. After the interface modification material 3 penetrated into the gaps between the quantum dots 41 of the quantum dot light-emitting layer 4, the mixture was spin-coated at a speed of 3000 r / s for 30 seconds, and then baked at 80° C. for 5 minutes to obtain the electron transport layer 5.

[0093] At a vacuum degree of 3x10 -4 Under the condition of Pa, an Ag electrode was evaporated at a rate of 1 angstrom / second for 1000 seconds, and the thickness of Ag was 100 nm, thereby obtaining a quantum dot light-emitting diode 100.

[0094] The interface modification material 3 of the quantum dot light-emitting diode 100 of this embodiment is filled in the gaps between the quantum dot light-emitting layer 4 and the electron transport layer 5, in the gaps between the quantum dots 41 in the area of ​​the quantum dot light-emitting layer 4 adjacent to the electron transport layer 5, and in the gaps between the electron transport materials 51 of the electron transport layer 5.

[0095] Example 3

[0096] Preparation of quantum dot light-emitting diodes 100

[0097] Providing a substrate 1 with an ITO bottom electrode 2 bonded to its surface;

[0098] Print the PEDOT:PSS hybrid material on the ITO bottom electrode 2 and bake it at 150°C for 15 minutes to obtain the hole injection layer;

[0099] Printing TFB with a concentration of 8 mg / mL on the hole injection layer, and then baking at 80° C. for 10 min to obtain a hole transport layer;

[0100] Providing an interface modification material PEI, an electron transport material nano ZnO and an organic solvent ethylene glycol monomethyl ether, adding PEI and nano ZnO to the ethylene glycol monomethyl ether and mixing them evenly to obtain a PEI: nano ZnO mixed solution, wherein the concentration of PEI is 0.1 wt%;

[0101] A quantum dot material with a concentration of 20 mg / mL was spin-coated on the surface of the hole transport layer at a rotation speed of 2000 r / s for 30 seconds, and the mixed solution was added dropwise within 2 seconds after the start of spin coating. After the film was formed, it was baked at 80° C. for 5 minutes to obtain a quantum dot light-emitting layer 4, a transition layer 10 bonded to the quantum dot light-emitting layer 4, and an electron transport layer 5 bonded to the transition layer 10;

[0102] At a vacuum degree of 3x10 -4 Pa, an Al electrode was evaporated at a rate of 1 Å / s for 100 seconds, with an Al thickness of 10 nm;

[0103] At a vacuum degree of 3x10 -4 Under the condition of Pa, an Ag electrode was evaporated at a rate of 1 angstrom / second for 200 seconds, and the thickness of Ag was 20 nm, thereby obtaining a quantum dot light-emitting diode 100.

[0104] In the quantum dot light-emitting diode 100 of this embodiment, the interface modification material 3 is filled in the gaps between the quantum dots 41 in the transition layer 10, the gaps between the electron transport materials 51, and the gaps between the quantum dots 41 and the electron transport material 51. The interface modification material 3 is also filled in the gaps between the quantum dot light-emitting layer 4 and the transition layer 10, between the transition layer 10 and the electron transport layer 5, in the gaps between the quantum dots 41 in the region of the quantum dot light-emitting layer 4 on the side adjacent to the transition layer 10, and in the gaps between the electron transport materials in the electron transport layer 5.

[0105] Example 4

[0106] Preparation of quantum dot light-emitting diodes 100

[0107] Providing a substrate 1 with an ITO bottom electrode 2 bonded to its surface;

[0108] Print the PEDOT:PSS hybrid material on the ITO bottom electrode 2 and bake it at 150°C for 15 minutes to obtain the hole injection layer;

[0109] Printing TFB with a concentration of 8 mg / mL on the hole injection layer, and then baking at 80° C. for 10 min to obtain a hole transport layer;

[0110] Providing an interface modification material PEI, an electron transport material nano ZnO and an organic solvent ethylene glycol monomethyl ether, adding PEI and nano ZnO to the ethylene glycol monomethyl ether and mixing them evenly to obtain a PEI: nano ZnO mixed solution, wherein the concentration of PEI is 0.1 wt%;

[0111] A quantum dot material with a concentration of 20 mg / mL was spin-coated on the surface of the hole transport layer at a rotation speed of 2000 r / s for 30 seconds, and the mixed solution was added dropwise within 2 seconds after the start of spin coating. After the film was formed, it was baked at 80° C. for 5 minutes to obtain a quantum dot light-emitting layer 4, a transition layer 10 bonded to the quantum dot light-emitting layer 4, and an electron transport layer 5 bonded to the transition layer 10;

[0112] At a vacuum degree of 3x10 -4 Under the condition of Pa, an Ag electrode was evaporated at a rate of 1 angstrom / second for 1000 seconds, and the thickness of Ag was 100 nm, thereby obtaining a quantum dot light-emitting diode 100.

[0113] In the quantum dot light-emitting diode 100 of this embodiment, the interface modification material 3 is filled in the gaps between the quantum dots 41 in the transition layer 10, the gaps between the electron transport materials 51, and the gaps between the quantum dots 41 and the electron transport material 51. The interface modification material 3 is also filled in the gaps between the quantum dot light-emitting layer 4 and the transition layer 10, between the transition layer 10 and the electron transport layer 5, in the gaps between the quantum dots 41 in the region of the quantum dot light-emitting layer 4 on the side adjacent to the transition layer 10, and in the gaps between the electron transport materials in the electron transport layer 5.

[0114] Example 5

[0115] Preparation of quantum dot light-emitting diodes 100

[0116] Providing a substrate 1 with an ITO bottom electrode 2 bonded to its surface;

[0117] Print the PEDOT:PSS hybrid material on the ITO bottom electrode 2 and bake it at 150°C for 15 minutes to obtain the hole injection layer;

[0118] Printing TFB with a concentration of 8 mg / mL on the hole injection layer, and then baking at 80° C. for 10 min to obtain a hole transport layer;

[0119] Providing an interface modification material PEI, an electron transport material nano ZnO and an organic solvent ethanol, adding PEI and nano ZnO into the ethanol, and mixing them evenly to obtain a PEI: nano ZnO mixed solution, wherein the concentration of PEI is 0.1 wt%;

[0120] Printing a quantum dot material with a concentration of 20 mg / mL on the surface of the hole transport layer to obtain a quantum dot light-emitting layer 4;

[0121] The mixed solution is dropped onto the quantum dot light-emitting layer 4 and allowed to stand for 5 seconds. After the interface modification material 3 penetrates into the gaps between the quantum dots 41 of the quantum dot light-emitting layer 4, a film is formed. The film is then baked at 80° C. for 5 minutes to obtain the electron transport layer 5.

[0122] At a vacuum degree of 3x10 -4 Pa, an Al electrode was evaporated at a rate of 1 Å / s for 100 seconds, with an Al thickness of 10 nm;

[0123] At a vacuum degree of 3x10 -4 Under the condition of Pa, an Ag electrode was evaporated at a rate of 1 angstrom / second for 200 seconds, and the thickness of Ag was 20 nm, thereby obtaining a quantum dot light-emitting diode 100.

[0124] The interface modification material 3 of the quantum dot light-emitting diode 100 of this embodiment is filled in the gaps between the quantum dot light-emitting layer 4 and the electron transport layer 5, in the gaps between the quantum dots 41 in the area of ​​the quantum dot light-emitting layer 4 adjacent to the electron transport layer 5, and in the gaps between the electron transport materials 51 of the electron transport layer 5.

[0125] Example 6

[0126] Preparation of quantum dot light-emitting diodes 100

[0127] Providing a substrate 1 with an ITO bottom electrode 2 bonded to its surface;

[0128] Print the PEDOT:PSS hybrid material on the ITO bottom electrode 2 and bake it at 150°C for 15 minutes to obtain the hole injection layer;

[0129] Printing TFB with a concentration of 8 mg / mL on the hole injection layer, and then baking at 80° C. for 10 min to obtain a hole transport layer;

[0130] Providing an interface modification material PEI, an electron transport material nano ZnO and an organic solvent ethanol, adding PEI and nano ZnO into the ethanol, and mixing them evenly to obtain a PEI: nano ZnO mixed solution, wherein the concentration of PEI is 0.1 wt%;

[0131] Printing quantum dot material on the surface of the hole transport layer to obtain a quantum dot light-emitting layer 4;

[0132] The mixed solution is dropped onto the quantum dot light-emitting layer 4 and allowed to stand for 5 seconds. After the interface modification material 3 penetrates into the gaps between the quantum dots 41 of the quantum dot light-emitting layer 4, the mixed solution is coated into a film, and then baked at 80° C. for 5 minutes to obtain the electron transport layer 5.

[0133] At a vacuum degree of 3x10 -4 Under the condition of Pa, an Ag electrode was evaporated at a rate of 1 angstrom / second for 1000 seconds, and the thickness of Ag was 100 nm, thereby obtaining a quantum dot light-emitting diode 100.

[0134] The interface modification material 3 of the quantum dot light-emitting diode 100 of this embodiment is filled in the gaps between the quantum dot light-emitting layer 4 and the electron transport layer 5, in the gaps between the quantum dots 41 in the area of ​​the quantum dot light-emitting layer 4 adjacent to the electron transport layer 5, and in the gaps between the electron transport materials 51 of the electron transport layer 5.

[0135] Example 7

[0136] Preparation of quantum dot light-emitting diodes 100

[0137] Providing a substrate 1 with an ITO bottom electrode 2 bonded to its surface;

[0138] A PEDOT:PSS mixed material was printed on the ITO bottom electrode 2 and then baked at 150°C for 15 minutes to obtain a hole injection layer;

[0139] Printing TFB with a concentration of 8 mg / mL on the hole injection layer, and then baking at 80° C. for 10 min to obtain a hole transport layer;

[0140] Providing an interface modification material PEI, an electron transport material nano ZnO and an organic solvent ethanol, adding PEI and nano ZnO into the ethanol, and mixing them evenly to obtain a PEI: nano ZnO mixed solution, wherein the concentration of PEI is 0.1 wt%;

[0141] Printing quantum dot material on the surface of the hole transport layer to obtain a quantum dot wet film, then dripping the mixed solution on the surface of the quantum dot wet film, baking at 80° C. for 5 minutes after film formation, to obtain a quantum dot light-emitting layer 4, a transition layer 10 bonded to the quantum dot light-emitting layer 4, and an electron transport layer 5 bonded to the transition layer 10;

[0142] At a vacuum degree of 3x10 -4 Pa, an Al electrode was evaporated at a rate of 1 Å / s for 100 seconds, with an Al thickness of 10 nm;

[0143] At a vacuum degree of 3x10 -4 Under the condition of Pa, an Ag electrode was evaporated at a rate of 1 angstrom / second for 200 seconds, and the thickness of Ag was 20 nm, thereby obtaining a quantum dot light-emitting diode 100.

[0144] In the quantum dot light-emitting diode 100 of this embodiment, the interface modification material 3 is filled in the gaps between the quantum dots 41 in the transition layer 10, the gaps between the electron transport materials 51, and the gaps between the quantum dots 41 and the electron transport material 51. The interface modification material 3 is also filled in the gaps between the quantum dot light-emitting layer 4 and the transition layer 10, between the transition layer 10 and the electron transport layer 5, in the gaps between the quantum dots 41 in the region of the quantum dot light-emitting layer 4 on the side adjacent to the transition layer 10, and in the gaps between the electron transport materials in the electron transport layer 5.

[0145] Example 8

[0146] Preparation of quantum dot light-emitting diodes 100

[0147] Providing a substrate 1 with an ITO bottom electrode 2 bonded to its surface;

[0148] The PEDOT:PSS mixed material was spin-coated on the ITO bottom electrode 2 at a rotation speed of 5000 r / s for 30 seconds, and then baked at 150°C for 15 minutes to obtain a hole injection layer;

[0149] The hole injection layer was spin-coated with 8 mg / mL TFB at a rotation speed of 3000 r / s for 30 seconds, and then baked at 80° C. for 10 minutes to obtain a hole transport layer;

[0150] Providing an interface modification material PEI, an electron transport material nano ZnO and an organic solvent ethanol, adding PEI and nano ZnO into ethanol and mixing them evenly to obtain a PEI: nano ZnO mixed solution, wherein the concentration of PEI / PEIE is 0.1 wt%;

[0151] A quantum dot material with a concentration of 20 mg / mL was spin-coated on the surface of the hole transport layer at a rotation speed of 2000 r / s for 30 seconds, and the mixed solution was added dropwise within 2 seconds after the start of spin coating. After the film was formed, it was baked at 80° C. for 5 minutes to obtain a quantum dot light-emitting layer 4, a transition layer 10 bonded to the quantum dot light-emitting layer 4, and an electron transport layer 5 bonded to the transition layer 10;

[0152] At a vacuum degree of 3x10 -4 Under the condition of Pa, an Ag electrode was evaporated at a rate of 1 angstrom / second for 1000 seconds, and the thickness of Ag was 100 nm, thereby obtaining a quantum dot light-emitting diode 100.

[0153] In the quantum dot light-emitting diode 100 of this embodiment, the interface modification material 3 is filled in the gaps between the quantum dots 41 in the transition layer 10, the gaps between the electron transport materials 51, and the gaps between the quantum dots 41 and the electron transport material 51. The interface modification material 3 is also filled in the gaps between the quantum dot light-emitting layer 4 and the transition layer 10, between the transition layer 10 and the electron transport layer 5, in the gaps between the quantum dots 41 in the region of the quantum dot light-emitting layer 4 on the side adjacent to the transition layer 10, and in the gaps between the electron transport materials in the electron transport layer 5.

[0154] Comparative Example 1

[0155] Preparation of conventional quantum dot light-emitting diodes

[0156] Providing a substrate with an ITO bottom electrode bonded to its surface;

[0157] Print the PEDOT:PSS hybrid material on the ITO bottom electrode and bake it at 150°C for 15 minutes to obtain the hole injection layer;

[0158] Printing TFB with a concentration of 8 mg / mL on the hole injection layer, and then baking at 80° C. for 10 min to obtain a hole transport layer;

[0159] Printing a quantum dot material with a concentration of 20 mg / mL on the surface of the hole transport layer to obtain a quantum dot light-emitting layer;

[0160] Printing nano ZnO with a concentration of 30 mg / mL on the quantum dot light-emitting layer, and then baking at 80° C. for 30 min to obtain an electron transport layer;

[0161] At a vacuum degree of 3x10 -4 Pa, an Al electrode was evaporated at a rate of 1 Å / s for 100 seconds, with an Al thickness of 10 nm;

[0162] At a vacuum degree of 3x10 -4 Under the condition of Pa, Ag electrode was evaporated at a rate of 1 angstrom / second for 200 seconds, and the thickness of Ag was 20 nm to obtain a conventional quantum dot light-emitting diode.

[0163] Comparative Example 2

[0164] Preparation of conventional quantum dot light-emitting diodes

[0165] Providing a substrate with an ITO bottom electrode bonded to its surface;

[0166] Print the PEDOT:PSS hybrid material on the ITO bottom electrode and bake it at 150°C for 15 minutes to obtain the hole injection layer;

[0167] Printing TFB with a concentration of 8 mg / mL on the hole injection layer, and then baking at 80° C. for 10 min to obtain a hole transport layer;

[0168] Printing a quantum dot material with a concentration of 20 mg / mL on the surface of the hole transport layer to obtain a quantum dot light-emitting layer;

[0169] Printing nano ZnO with a concentration of 30 mg / mL on the quantum dot light-emitting layer, and then baking at 80° C. for 30 min to obtain an electron transport layer;

[0170] At a vacuum degree of 3x10 -4 Under the condition of Pa, Ag electrode was evaporated at a rate of 1 angstrom / second for 1000 seconds, and the thickness of Ag was 20 nm to obtain a conventional quantum dot light-emitting diode.

[0171] The JVL data of the quantum dot light-emitting diodes prepared in Example 1 and Comparative Example 1 were tested.

[0172] The QLEDJVL test method is: use Keithley2400 to apply voltage to the quantum dot light-emitting diode starting from -0.6V, where the voltage step is 0.2V and the voltage application range is -0.6V to 8V; as the voltage is applied, the device current density and brightness change with voltage are recorded, and a curve diagram of current density change with voltage is obtained (see Figure 4 ), the curve of brightness changing with voltage (refer to Figure 5 ); By calculating the external quantum efficiency and current efficiency of the device, the external quantum efficiency-voltage curve is obtained (refer to Figure 6 ), current efficiency-voltage curve (refer to Figure 7 ).

[0173] Depend on Figure 5-7 It can be seen that when the quantum dot light-emitting diode is prepared using the solution of Example 1, the turn-on voltage of the device will decrease due to the modification of PEI, while the device brightness, external quantum efficiency and current efficiency will be greatly improved.

[0174] The working life of the quantum dot light-emitting diodes prepared in Example 1 and Comparative Example 1 was tested.

[0175] How QLED lifespan testing works:

[0176] The 128-channel QLED lifespan test system communicates via the central processing computer's PCI bus, controlling a National Instruments (NI) digital I / O card to select channels and output digital signals. The corresponding digital signals are converted to analog signals via a D / A chip, resulting in current output (I), which is then collected via a data acquisition card. Luminance is collected by converting optical signals into electrical signals using sensors, which are then used to simulate brightness changes (L).

[0177] QLED life test method:

[0178] Select 3-4 different constant current densities (e.g. 100 mA / cm 2 , 50mA / cm 2 , 20mA / cm 2 , 10mA / cm 2 ), test the initial brightness under the corresponding conditions; maintain a constant current, record the changes in brightness and device voltage over time, and obtain a brightness-time curve (refer to Figure 8 ); record the time T95, T80, T75, and T50 for the device brightness to decay to 95%, 80%, 75%, and 50% at different constant currents; calculate the acceleration factor by curve fitting; and extrapolate the time T for the device brightness to decay from 1000 nits to 95%, i.e., the device lifetime, using an empirical formula.

[0179] The empirical formula is: T = (L MAX / 1000) A*T95 .

[0180] Among them, L MAX is the maximum brightness, and A is the acceleration factor.

[0181] The life curve of the quantum dot light emitting diode of Example 1 extrapolated by the above empirical formula is shown in FIG. Figure 9 .

[0182] Depend on Figure 9 It can be seen that when the quantum dot light-emitting diode is prepared using the solution of Example 1, the lifespan (T95) of the device will be greatly improved.

[0183] The above is a detailed introduction to the preparation method of the quantum dot light-emitting diode provided in the examples of the present application. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above examples is only used to help understand the method of the present application and its core ideas. At the same time, for those skilled in the art, based on the ideas of the present application, there may be changes in the specific implementation methods and application scopes. In summary, the contents of this specification should not be understood as limiting the present application.

Claims

1. A method for preparing a quantum dot light-emitting diode, comprising the following steps: providing a substrate, and forming a bottom electrode on the substrate; Providing an interface modification material, an electron transport material and an organic solvent, mixing them to obtain a mixed solution; A quantum dot material is provided, the quantum dot material is disposed on a bottom electrode to form a quantum dot wet film, the mixed solution is then disposed on the surface of the quantum dot wet film by a solution method, the quantum dots on the surface of the quantum dot wet film are mixed with the electron transport material, and the film is dried after formation to obtain a quantum dot light-emitting layer, a transition layer bonded to the quantum dot light-emitting layer, and an electron transport layer bonded to the transition layer, wherein the transition layer contains quantum dots, an interface modification material, and an electron transport material, the quantum dots in the transition layer are derived from the quantum dot wet film, and the interface modification material in the transition layer is filled in gaps between the quantum dots, gaps between the electron transport material, and gaps between the quantum dots and the electron transport material in the transition layer; A top electrode is formed on the electron transport layer.

2. The method for preparing a quantum dot light-emitting diode according to claim 1, wherein: The quantum dot material is arranged on the bottom electrode to form a quantum dot wet film, and the mixed solution is arranged on the surface of the quantum dot wet film by a solution method, including: providing quantum dot material, spin-coating the quantum dot material on the bottom electrode to form a quantum dot wet film, and adding the mixed solution within a few seconds after the start of spin coating, and stopping the spin coating after the addition is completed.

3. The method for preparing a quantum dot light-emitting diode according to claim 1, wherein: The interface modification material is selected from one or more of polyethyleneimine, polyethoxyethyleneimine, poly[9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene]-2,7-(9,9-dioctylfluorene))], polyethylene glycol, conjugated polyelectrolyte or polyethylene oxide.

4. The method for preparing a quantum dot light-emitting diode according to claim 1, wherein: The electron transport material is selected from one or more of metal oxides, doped metal oxides, Group 2-6 semiconductor materials, Group 3-5 semiconductor materials and Group 1-3-6 semiconductor materials, the metal oxide is selected from one or more of ZnO, TiO2, and SnO2; the metal oxide in the doped metal oxide is selected from one or more of ZnO, TiO2, and SnO2, and the doping element is selected from one or more of aluminum, magnesium, indium, and gallium; the Group 2-6 semiconductor material is selected from one or more of ZnS, ZnSe, and CdS; the Group 3-5 semiconductor material is selected from at least one of InP and GaP; the Group 1-3-6 semiconductor material is selected from at least one of CuInS and CuGaS.

5. The method for preparing a quantum dot light-emitting diode according to claim 1, wherein: The organic solvent is selected from one or more of ethylene glycol monomethyl ether, isopropyl alcohol or ethanol.

6. The method for preparing a quantum dot light-emitting diode according to claim 1, wherein: In the mixed solution, the concentration range of the interface modification material is 0.1 wt%-10 wt%, and the concentration range of the electron transport material is 10-30 mg / mL.

7. A quantum dot light-emitting diode comprising a stacked bottom electrode, a quantum dot light-emitting layer, an electron transport layer, and a top electrode, wherein the quantum dot light-emitting layer comprises quantum dots, and the electron transport layer comprises an electron transport material, characterized in that: The gaps between adjacent quantum dots and electron transport materials are filled with interface modification materials. A transition layer is formed between the quantum dot light-emitting layer and the electron transport layer. The transition layer contains quantum dots, interface modification materials and electron transport materials. The interface modification materials in the transition layer are filled in the gaps between the quantum dots in the transition layer, in the gaps between the electron transport materials, and in the gaps between the quantum dots and the electron transport material.

8. The quantum dot light-emitting diode according to claim 7, wherein: The interface modification material is also filled in the gaps between the quantum dots on the side of the quantum dot light-emitting layer adjacent to the electron transport layer and in the gaps between the electron transport materials of the electron transport layer.

9. The quantum dot light-emitting diode according to claim 7, wherein: The interface modification material is also filled between the quantum dot light-emitting layer and the transition layer, and between the transition layer and the electron transport layer.

10. The quantum dot light-emitting diode according to claim 7, wherein: The interface modification material is selected from one or more of polyethyleneimine, polyethoxyethyleneimine, poly[9,9-bis(3'-(N,N-dimethylamino)propyl)-2,7-fluorene]-2,7-(9,9-dioctylfluorene))], polyethylene glycol, conjugated polyelectrolyte or polyethylene oxide; The electron transport material is selected from one or more of metal oxides, doped metal oxides, Group 2-6 semiconductor materials, Group 3-5 semiconductor materials and Group 1-3-6 semiconductor materials, the metal oxide is selected from one or more of ZnO, TiO2, and SnO2; the metal oxide in the doped metal oxide is selected from one or more of ZnO, TiO2, and SnO2, and the doping element is selected from one or more of aluminum, magnesium, indium, and gallium; the Group 2-6 semiconductor material is selected from one or more of ZnS, ZnSe, and CdS; the Group 3-5 semiconductor material is selected from at least one of InP and GaP; the Group 1-3-6 semiconductor material is selected from at least one of CuInS and CuGaS.

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