WO2022252608A1 - Quantum dot light-emitting diode and preparation method therefor - Google Patents

Abstract

The present application discloses a quantum dot light-emitting diode and a preparation method therefor. The preparation method comprises: forming a quantum dot film on a bottom electrode, then applying a mixed solution formed by an interface modification material, an electron transport material and an organic solvent to the surface of the quantum dot film, and drying to obtain a light-emitting layer and an electron transport layer. Thus, a contact mode between quantum dots and the electron transport material can be changed from conventional point contact to surface contact, thereby facilitating electron transport between the light-emitting layer and the electron transport layer.

Description

A quantum dot light-emitting diode and its preparation method

This application claims the priority of the Chinese patent application with the application number 202110622011.3 and the application title "A Quantum Dot Light-Emitting Diode and Its Preparation Method" filed at the China Patent Office on June 4, 2021, the entire contents of which are incorporated by reference incorporated in this application.

technical field

The present application relates to the field of display technology, in particular to a method for preparing a quantum dot light-emitting diode and a quantum dot light-emitting diode prepared by applying the method.

Background technique

QLED (Quantum Dots Light-Emitting Diode, quantum dot light-emitting device) is a new display device, its structure is similar to that of OLED (Organic Light-Emitting Diode, organic light-emitting device) is a new technology between liquid crystal and OLED. The core of QLED technology is quantum dots. Quantum dots are particles with a particle diameter of less than 10nm, mainly composed of zinc, cadmium, sulfur, and selenium atoms. When the quantum dot is stimulated by light, it will emit colored light. The color of the light is determined by the material of the quantum dot and the size and shape of the quantum dot. The unique quantum size effect, macroscopic quantum tunneling effect, quantum size effect and surface effect of quantum dots make them exhibit excellent physical properties, especially optical properties, such as adjustable spectrum, high luminous intensity, high color purity, long fluorescence lifetime, A single light source can excite multicolor fluorescence and other advantages.

At present, the luminous efficiency of QLED has basically met the needs of commercialization. In addition, QLED has a long lifespan and simple or no packaging process. It is expected to become the next generation of flat panel displays and has broad development prospects. However, in fact, the working life of the quantum dot light-emitting diodes prepared at this stage is far from the theoretical length, and the phenomenon of fluorescence quenching often occurs during the test process, which greatly restricts the quantum dot light-emitting devices. development progress. The main reason for such problems is that the transport rate of hole carriers and electron carriers in the quantum dot light-emitting diode is unbalanced, which makes the quantum dot charging and fluorescence quenching.

technical problem

Therefore, the balance of the transmission rate of hole carriers and electron carriers in the quantum dot light-emitting diodes in the prior art needs to be further improved.

technical solution

Therefore, the present application provides a method for preparing a quantum dot light-emitting diode and a quantum dot light-emitting diode prepared by using the method.

The embodiment of the present application provides a method for preparing a quantum dot light-emitting diode, which includes the following steps:

providing a substrate on which a bottom electrode is formed;

Provide interface modification materials, electron transport materials and organic solvents, and mix them to obtain a mixed solution;

Provide a quantum dot material, arrange the quantum dot material on the bottom electrode to form a quantum dot film, then place the mixed solution on the surface of the quantum dot film, and dry 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;

A top electrode is formed on the electron transport layer.

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 modifying material in the layer fills 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 materials.

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

Optionally, in some embodiments of the present application, a quantum dot material is provided, the quantum dot material is disposed on the bottom electrode to form a quantum dot film, and then the mixed solution is disposed on the quantum dot film surface, specifically:

Provide quantum dot material, arrange quantum dot material on the bottom electrode, form quantum dot dry film, after obtaining quantum dot light-emitting layer, add the mixed solution on the quantum dot light-emitting layer.

Optionally, in some embodiments of the present application, a quantum dot material is provided, the quantum dot material is disposed on the bottom electrode to form a quantum dot film, and then the mixed solution is disposed on the quantum dot film surface, specifically:

The quantum dot material is provided, and the quantum dot material is arranged on the bottom electrode to form a quantum dot wet film, and then the mixed solution is arranged on the surface of the quantum dot wet film by a solution method.

Optionally, in some embodiments of the present application, a quantum dot material is provided, the quantum dot material is disposed on the bottom electrode to form a quantum dot film, and then the mixed solution is disposed on the quantum dot film surface, specifically:

The quantum dot material is provided, and the quantum dot material is spin-coated on the bottom electrode to form a quantum dot wet film, and the mixed solution is added within a few seconds after the spin coating starts, and the spin coating is stopped after the addition is completed.

Optionally, in some embodiments of the present application, the rotational speed of the spin coating is 2000-3000 r/.

Optionally, in some embodiments of the present application, the number of seconds is 2-10 seconds.

Optionally, in some embodiments of the present application, the interface modification material is selected from polyethyleneimine, polyethoxyethyleneimine, poly[9,9-bis(3'-(N,N-di One of methylamino)propyl)-2,7-fluorene]-2,7-(9,9-dioctylfluorene))], polyethylene glycol, conjugated polyelectrolyte or polyethylene oxide or Several kinds.

Optionally, in some embodiments of the present application, the electron transport material is selected from metal oxides, doped metal oxides, 2-6 group semiconductor materials, 3-5 group semiconductor materials and 1-3-6 group One or more of semiconductor materials, the metal oxide is selected from one or more of ZnO, TiO ₂ , SnO ₂ ; the metal oxide in the doped metal oxide is selected from ZnO, TiO ₂ , SnO ₂ or more, the doping element is selected from one or more of aluminum, magnesium, indium, gallium; the 2-6 semiconductor group material is selected from one of ZnS, ZnSe, CdS or several; the 3-5 group semiconductor material is selected from at least one of InP and GaP; the 1-3-6 group semiconductor material is selected from at least one of CuInS and CuGaS.

Optionally, in some embodiments of the present application, the organic solvent is selected from one or more of ethylene glycol monomethyl ether, isopropanol or ethanol.

Optionally, in some embodiments of the present application, in the mixed solution, the concentration of the interface modification material ranges from 0.1wt% to 10wt%.

Optionally, in some embodiments of the present application, the concentration range of the electron transport material in the mixed solution is 10-30 mg/mL.

Correspondingly, the 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, the quantum dot light-emitting layer contains quantum dots, and the electrons The transport layer contains an electron transport material, wherein the gap between adjacent quantum dots and the electron transport material is filled with an interface modification material.

Optionally, in some embodiments of the present application, in the gap between the quantum dots on the side adjacent to the electron transport layer of the quantum dot light-emitting layer, and in the gap between the electron transport materials of the electron transport layer Also filled with the interface modifying material.

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, and the transition layer contains quantum dots, interface modification materials, and electrons. The transport material, the interface modifying material in the transition layer is filled in 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.

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.

Optionally, in some embodiments of the present application, the interface modification material is selected from polyethyleneimine, polyethoxyethyleneimine, poly[9,9-bis(3'-(N,N-di One of methylamino)propyl)-2,7-fluorene]-2,7-(9,9-dioctylfluorene))], polyethylene glycol, conjugated polyelectrolyte or polyethylene oxide or Several kinds.

Optionally, in some embodiments of the present application, the electron transport material is selected from metal oxides, doped metal oxides, 2-6 group semiconductor materials, 3-5 group semiconductor materials and 1-3-6 group One or more of semiconductor materials, the metal oxide is selected from one or more of ZnO, TiO ₂ , SnO ₂ ; the metal oxide in the doped metal oxide is selected from ZnO, TiO ₂ , SnO ₂ or more, the doping element is selected from one or more of aluminum, magnesium, indium, gallium; the 2-6 semiconductor group material is selected from one of ZnS, ZnSe, CdS or several; the 3-5 group semiconductor material is selected from at least one of InP and GaP; the 1-3-6 group semiconductor material is selected from at least one of CuInS and CuGaS.

Beneficial effect

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 arranged on the surface of the quantum dot light-emitting layer, the interface modification material will penetrate with the organic solvent into the gap between the quantum dots. 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, the gap between the electron transport materials of the electron transport layer, and the adjacent quantum dots. In the gap between the dots and the electron transport material. In this way, the contact mode between the quantum dots and the electron transport material is changed from the conventional point contact to the surface contact, which can effectively increase the effective contact area between the quantum dot light-emitting layer and the electron transport layer, and promote the quantum dot light-emitting layer and electron transport. Electron transport between layers reduces or even avoids the problem of unbalanced transport rates of hole carriers and electron carriers, thereby avoiding quantum dot charging and fluorescence quenching.

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 arranges the mixed solution on the surface of the quantum dot wet film, so that the interface modification material will As the organic solvent penetrates into the gaps of the quantum dots, and the quantum dots on the surface of the quantum dot wet film and the electron transport material will be mixed due to factors such as gravity, the effective contact area between the quantum dot light-emitting layer and the electron transport layer can be further increased. Promote electron transport between the quantum dot light-emitting layer and the electron transport layer.

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 dot and the electron transport material, it has a regulating effect on the material interface, which can Reduce the interfacial barrier of the material, thereby facilitating the transport of charges. In addition, due to the small particle size of quantum dots and electron transport materials, both of which are nanostructures, the materials have a large specific surface area and a high content of surface defects, which will have a strong capture effect on free charges, resulting in non-fluorescence recombination, resulting in device Poor performance. However, under the coating effect of interface modification materials, the surface defects of nanoparticles will be passivated, which can reduce non-fluorescence recombination and improve device performance.

Description of drawings

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

Fig. 1 is the flow chart of the preparation method of the quantum dot light-emitting diode provided by the embodiment of the present application;

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

Fig. 3 is a schematic diagram of another quantum dot light-emitting diode provided by the embodiment of the present application;

Fig. 4 is the graph that the current density of the quantum dot light-emitting diode of the application embodiment 1 and comparative example 1 changes with the voltage;

Fig. 5 is the graph that the brightness of the quantum dot light-emitting diode of the application embodiment 1 and comparative example 1 changes with voltage;

Fig. 6 is the external quantum efficiency-voltage curve diagram of the quantum dot light-emitting diode of embodiment 1 and comparative example 1 of the present application;

Fig. 7 is the current efficiency-voltage curve diagram of the quantum dot light-emitting diode of embodiment 1 and comparative example 1 of the present application;

Fig. 8 is the luminance-time graph of the quantum dot light-emitting diodes of Example 1 and Comparative Example 1 of the present application;

FIG. 9 is a graph of the lifespan of the quantum dot light-emitting diode in Example 1 extrapolated by the present application through an empirical formula.

Embodiment of this application

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

The embodiment of the present application provides a quantum dot light-emitting diode and a preparation method thereof. Each will be described in detail below. It should be noted that the description sequence of the following embodiments is not intended to limit the preferred sequence of the embodiments. In addition, in the description of the present application, the term "including" means "including but not limited to". The expressions "one or more" and "at least one" in this application refer to one or more of the listed items, and "multiple" refers to any of two or more of these items. Combinations, including any combination of single or plural terms (species), for example, "at least one (species) of a, b, or c" or "at least one (species) of a, b, and c" , can represent: a, b, c, a-b (that is, a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple. Various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the application; therefore, the described range should be regarded as The description has specifically disclosed all possible subranges as well as individual values within that range. For example, a description of a range from 1 to 6 should be considered to have specifically disclosed subranges, 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., and Single numbers within the stated ranges, eg 1, 2, 3, 4, 5 and 6, apply regardless of the range. Additionally, whenever a numerical range is indicated herein, it is meant to include any cited numeral (fractional or integral) within the indicated range.

Please refer to FIGS. 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:

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

Step S2: Provide the interface modification material 3, the electron transport material 51 and an organic solvent, mix them, 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;

Step S3: providing a quantum dot material, placing the quantum dot material on the bottom electrode 2 to form a quantum dot film, and then placing the mixed solution on the surface of the quantum dot film by a solution method, forming a film, drying, Obtain the quantum dot luminescent layer 4 and the electron transport layer 5 combined with the quantum dot luminescent layer 4;

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

In the step S3, the method for disposing the quantum dot material on the bottom electrode 2 may be a chemical film-forming method or a physical film-forming method known in the art. The chemical film-forming methods include: chemical vapor deposition, continuous ion layer adsorption and reaction, anodic oxidation, electrolytic deposition, and co-precipitation. Physical film forming methods include physical coating methods and solution processing methods. Specifically, physical coating methods include: thermal evaporation coating method, electron beam evaporation coating method, magnetron sputtering method, multi-arc ion coating method, physical vapor deposition method, atomic Layer deposition method, pulsed laser deposition method, etc.; solution processing methods include spin coating method, printing method, inkjet printing method, scraping method, printing method, dipping and pulling method, soaking method, spraying method, roll coating method, casting method , Slit coating method, strip coating method.

The quantum dot film may be a dried quantum dot film or an undried quantum dot wet film. Wherein, the quantum dot dry film is the quantum dot light-emitting layer 4 .

Please refer to Fig. 2, in one embodiment, described step S3 is S03: provide quantum dot material, quantum dot material is arranged on the bottom electrode 2, forms quantum dot dry film, after obtaining quantum dot light-emitting layer 4, the The mixed solution is added to the quantum dot light-emitting layer 4, so that the interface modification material 3 penetrates at least into the gap of 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 to form a film, and dried to obtain the electron transport layer 5. The interface modification material 3 is filled in the gaps between the quantum dots 41 of the quantum dot luminescent layer 4, in the gaps between the electron transport materials 51 of the electron transport layer 5, and between the adjacent quantum dots 41 and In the gap between electron transport materials 51 . In this way, the contact mode between the quantum dots 41 and the electron transport material 51 is changed from the conventional point contact to the surface contact, which can effectively increase the effective contact area between the quantum dot method light-emitting layer 4 and the electron transport layer 5, and promote the quantum dot method. The electron transport between the light-emitting layer 4 and the electron transport layer 5 reduces or even avoids the problem of unbalanced transport rates of hole carriers and electron carriers, thereby avoiding charging of quantum dots 41 and quenching of fluorescence.

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

Please refer to Fig. 3, in another embodiment, described step S3 is S13: provide quantum dot material, described quantum dot material is arranged on the bottom electrode 2, forms quantum dot wet film, then described mixed solution passes through The solution method is arranged on the surface of the quantum dot wet film, the quantum dots on the surface of the quantum dot wet film are mixed with the electron transport material, and dried after film formation to obtain the quantum dot light-emitting layer 4, which is combined with the quantum dot light-emitting layer 4 The transition layer 10, and the electron transport layer 5 combined with the transition layer 10. The transition layer 10 includes quantum dots 41 , an interface modification material 3 and an electron transport material 51 . The interface modification material 3 in the transition layer 10 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 materials 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 between the quantum dot luminescent layer 4 and the transition layer 10, between the transition layer 10 and the electron transport layer 5, and the quantum dots of the quantum dot luminescent layer 4 41 , and in the gap between the electron transport materials 51 of the electron transport layer 5 . The mixed solution is arranged on the surface of the quantum dot wet film by a solution method, so that the quantum dots 41 on the surface of the quantum dot wet film can be mixed with the electron transport material 51, and the quantum dots 41 and the electron transport material 51 can be mutually mixed. A mixed transition layer can further increase the effective contact area between the quantum dot light-emitting layer 4 and the electron transport layer 5, and promote the electron transport between the quantum dot light-emitting layer 4 and the electron transport layer 5.

In a preferred embodiment, said S13 is: provide the quantum dot material, spin coat the quantum dot material on the bottom electrode 2 to form a quantum dot wet film, and within a few seconds after the spin coating starts (that is, the spin coating starts and before the quantum dot material forms a dry film), add the mixed solution, stop the spin coating after the addition, and dry after film formation to obtain the quantum dot light-emitting layer 4, the transition layer 10 combined with the quantum dot light-emitting layer 4, and Electron transport layer 5 bonded to transition layer 10 . Add the mixed solution dropwise within a few seconds after the start of the spin-coating quantum dot material, the interface modification material 3 will penetrate into the quantum dot gap of the quantum dot wet film along with the organic solvent, and in the spin coating process, the surface of the quantum dot wet film The quantum dots and electron transport materials can be better intermixed.

It can be understood that, in one embodiment, the interstices of all quantum dots in the quantum dot light-emitting layer 4 are filled with the interface modification material 3 . In yet another embodiment, the gap between the quantum dots 41 in the region of the quantum dot light-emitting layer 4 adjacent to the side of the electron transport layer 5 is filled with the interface modification material 3, away from the electron transport layer 5 The gap between the quantum dots 41 in the region on one side is not filled with the interface modification material 3 .

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

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

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-dimethyl (amino)propyl)-2,7-fluorene]-2,7-(9,9-dioctylfluorene))]), PEG (polyethylene glycol), CPE (conjugated polyelectrolyte), PEO ( One or more of polyethylene oxide). 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 between the quantum dot 41 and the electron transport material 51, it can regulate the interface of the material, and can reduce the interface barrier of the material. thereby facilitating the transport of charges. In addition, due to the small particle size of the quantum dots 41 and the electron transport material 51, both of which are nanostructures, the materials have a large specific surface area and a high content of surface defects, which will have a strong trapping effect on free charges, resulting in non-fluorescent recombination. result 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-fluorescence recombination and improve device performance.

In some embodiments, in the mixed solution, the concentration of the interface modification material 3 ranges from 0.1 wt% to 10 wt%. Under this concentration condition, the viscosity of the mixed solution is moderate, and the interface modification material 3 can effectively penetrate into the gaps of the quantum dots 41 of the quantum dot light-emitting layer 4 . If the concentration is too high, the viscosity of the solution mixed solution will be greatly increased, increasing the difficulty of the interface modification material 3 infiltrating into the gap of the quantum dot 41, increasing the thickness of the interface modification material between the quantum dot light-emitting layer 4 and the electron transport layer 5, thereby Increased resistance to charge transfer.

In the mixed solution, the concentration range of the electron transport material 51 is 10-30 mg/mL. The electron transport material 51 is a material conventionally used in the field of 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 (TiO ₂ ), tin oxide (SnO ₂ ); the metal in the doped metal oxide The oxide is selected from but not limited to at least one of ZnO, TiO ₂ , and SnO ₂ , and the doping element is selected from but not limited to one or more of aluminum, magnesium, indium, and gallium; the 2-6 semiconductor group The material is selected from but not limited to one or more of ZnS, ZnSe, and CdS; the 3-5 semiconductor group material is selected from but not limited to at least one of InP and GaP; the 1-3-6 group semiconductor The material is selected from but not limited to at least one of CuInS and CuGaS. In some embodiments, the electron transport material 51 is nano-ZnO, nano-TiO ₂ or nano-SnO ₂ . In at least one specific embodiment, the particle size of the nano ZnO is less than 20nm.

The organic solvent is a conventionally used solvent in this field. The organic solvent is a high-viscosity solvent or a low-viscosity solvent. The high-viscosity solvent may be ethylene glycol monomethyl ether (EGME, viscosity 1.7 mPa•s), isopropanol (viscosity 2.4 mPa•s), and the like. The low-viscosity solvent may be ethanol (viscosity 1.2 mPa·s) or the like. In some embodiments, the organic solvent is a low-viscosity solvent, which facilitates the penetration of the interface modification material 3 into the gaps of the quantum dots 41 .

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

In the step S03, after adding the mixed solution to the quantum dot luminescent layer 4, it also includes a step of standing still, so that the interface modification material 3 can fully penetrate into the vicinity of the quantum dot luminescent layer 4 In the gap between the quantum dots 41 on the side of the electron transport layer 5 . In some embodiments, the resting time is 5-10 seconds. In some embodiments, the method for forming the quantum dot film is spin coating film formation, the spin coating film formation speed ranges from 2000-3000r/s, and the time range is 20-30s.

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

In the step S4, the method of forming the top electrode 6 on the electron transport layer 5 is a conventional method in the field, such as evaporation and the like. The top electrode 6 is a cathode, and the cathode is a cathode commonly used in this field, such as Al, Ag, Al/Ag, Cu, Au and alloy electrodes. In at least one embodiment, the vapor deposition method is as follows: by thermal evaporation, the vacuum degree is not higher than 3×10 ^-4 Pa, and the vapor deposition is performed for 1000-2000 seconds at a speed of 0.5-1 angstroms/second.

It can be understood that before forming the quantum dot light-emitting layer 4 on the bottom electrode 2, a step of forming at least one of a hole transport layer and a hole injection layer on the bottom electrode 2 is also included. The method for forming the hole transport layer and the hole injection layer is a conventional method in the field, such as evaporation and the like.

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

In at least one embodiment, the method of forming the hole transport layer is: spin-coat the material of the hole transport layer on the bottom electrode 2 or the hole injection layer, and then bake. The rotating speed of the spin coating is 3000r/s, and the time is 30 seconds. The baking temperature is 80° C., and the baking time is 10-30 minutes. The material of the hole transport layer is a material conventionally used in the field of the hole transport layer, such as TFB (nickel etchant).

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 also be included.

The embodiment of the present application also provides a quantum dot light-emitting diode 100 , which includes 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 sequentially stacked. 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 LED 100 also includes an interface modification material 3 . The interface modification material 3 is filled in the gaps between the quantum dots 41 of the quantum dot luminescent layer 4, in the gaps between the electron transport materials 51 of the electron transport layer 5, and between the adjacent quantum dots 41 and In the gap between electron transport materials 51 .

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

In one embodiment, the gaps of all the quantum dots 41 in the quantum dot light-emitting layer 4 are filled with the interface modification material 3 . In yet another embodiment, the gap between the quantum dots 41 in the region of the quantum dot luminescent layer 4 adjacent to the electron transport layer 5 is filled with an interface modification material 3, and the quantum dot luminescent layer 4 The gap between the quantum dots 41 in the region on the side away from the electron transport layer 5 is not filled with the interface modification material 3 .

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 .

It can be understood that the quantum dot LED 100 also includes an electron injection layer located between the electron transport layer 5 and the top electrode 6 .

The embodiment of the present application 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 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 LED 100 also includes an interface modification material 3 . The transition layer 10 includes quantum dots 41 , electron transport materials 51 and interface modification materials 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 materials 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 between the quantum dot luminescent layer 4 and the transition layer 10, between the transition layer 10 and the electron transport layer 5, and between the quantum dots 41 of the quantum dot luminescent layer 4 In the gap between, and in the gap between the electron transport material 51 of the electron transport layer 5 .

In one embodiment, the gaps of all the quantum dots 41 in the quantum dot light-emitting layer 4 are filled with the interface modification material 3 . In yet another embodiment, the gap between the quantum dots 41 in the region of the quantum dot luminescent layer 4 adjacent to the transition layer 10 is filled with the interface modification material 3, and the quantum dot luminescent layer 4 The gap between the quantum dots 41 in the region away from the transition layer 10 is not filled with the interface modification material 3 .

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 .

It can be understood that the quantum dot LED 100 also includes an electron injection layer located between the electron transport layer 5 and the top electrode 6 .

The following examples will be used to describe the present application in detail. The following examples are only partial implementations of the present application, and are not intended to limit the present application.

Example 1

Preparation of Quantum Dot Light-Emitting Diode 100

A substrate 1 with an ITO bottom electrode 2 bonded to its surface is provided;

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

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

Provide interface modification material PEI, electron transport material nano-ZnO and organic solvent ethylene glycol monomethyl ether, add PEI and nano-ZnO to ethylene glycol monomethyl ether, and mix well to obtain a mixed solution of PEI:nano-ZnO, wherein, The concentration of PEI is 0.1wt%;

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;

Print the mixed solution on the quantum dot light-emitting layer 4, and after standing for 5 seconds, bake at 80° C. for 5 minutes to obtain an electron transport layer 5;

Under the condition of vacuum degree of 3×10 ^-4 Pa, evaporate the Al electrode at a speed of 1 Angstrom/second for 100 seconds, and the thickness of Al is 10nm;

Under the condition of a vacuum degree of 3×10 ⁻⁴ Pa, an Ag electrode was vapor-deposited at a rate of 1 Å/sec for 200 seconds, and the thickness of Ag was 20 nm to obtain a quantum dot light-emitting diode 100 .

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

Example 2

Preparation of Quantum Dot Light-Emitting Diode 100

A substrate 1 with an ITO bottom electrode 2 bonded to its surface is provided;

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

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

Provide interface modification material PEI, electron transport material nano-ZnO and organic solvent ethylene glycol monomethyl ether, add PEI and nano-ZnO to ethylene glycol monomethyl ether, and mix well to obtain a mixed solution of PEI:nano-ZnO, wherein, The concentration of PEI is 0.1wt%;

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

Add the mixed solution dropwise on the quantum dot luminescent layer 4, and let it stand for 5 seconds. After the interface modification material 3 penetrates into the gaps of the quantum dots 41 of the quantum dot luminescent layer 4, start the process at a speed of 3000r/s. Spin coating at a rotational speed for 30 seconds, and then bake at 80° C. for 5 minutes to obtain an electron transport layer 5;

Under the condition of a vacuum degree of 3×10 ⁻⁴ Pa, the Ag electrode was vapor-deposited at a rate of 1 angstrom/second for 1000 seconds, and the Ag thickness was 100 nm to obtain a quantum dot light-emitting diode 100 .

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

Example 3

Preparation of Quantum Dot Light-Emitting Diode 100

A substrate 1 with an ITO bottom electrode 2 bonded to its surface is provided;

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

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

Provide interface modification material PEI, electron transport material nano-ZnO and organic solvent ethylene glycol monomethyl ether, add PEI and nano-ZnO to ethylene glycol monomethyl ether, and mix well to obtain a mixed solution of PEI:nano-ZnO, wherein, The concentration of PEI is 0.1wt%;

The surface of the hole transport layer is spin-coated with a concentration of 20mg/mL quantum dot material for 30 seconds at a speed of 2000r/s, and the mixed solution is added dropwise within 2 seconds after the start of the spin coating. Baking at ℃ for 5 minutes to obtain the quantum dot light-emitting layer 4, the transition layer 10 combined with the quantum dot light-emitting layer 4, and the electron transport layer 5 combined with the transition layer 10;

Under the condition of vacuum degree of 3×10 ^-4 Pa, evaporate the Al electrode at a speed of 1 Angstrom/second for 100 seconds, and the thickness of Al is 10nm;

Under the condition of a vacuum degree of 3×10 ⁻⁴ Pa, an Ag electrode was vapor-deposited at a rate of 1 Å/sec for 200 seconds, and the thickness of Ag was 20 nm to obtain a quantum dot light-emitting diode 100 .

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

Example 4

Preparation of Quantum Dot Light-Emitting Diode 100

A substrate 1 with an ITO bottom electrode 2 bonded to its surface is provided;

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

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

Provide interface modification material PEI, electron transport material nano-ZnO and organic solvent ethylene glycol monomethyl ether, add PEI and nano-ZnO to ethylene glycol monomethyl ether, and mix well to obtain a mixed solution of PEI:nano-ZnO, wherein, The concentration of PEI is 0.1wt%;

The surface of the hole transport layer is spin-coated with a concentration of 20mg/mL quantum dot material for 30 seconds at a speed of 2000r/s, and the mixed solution is added dropwise within 2 seconds after the start of the spin coating. Baking at ℃ for 5 minutes to obtain the quantum dot light-emitting layer 4, the transition layer 10 combined with the quantum dot light-emitting layer 4, and the electron transport layer 5 combined with the transition layer 10;

Under the condition of a vacuum degree of 3×10 ⁻⁴ Pa, the Ag electrode was vapor-deposited at a rate of 1 angstrom/second for 1000 seconds, and the Ag thickness was 100 nm to obtain a quantum dot light-emitting diode 100 .

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

Example 5

Preparation of Quantum Dot Light-Emitting Diode 100

A substrate 1 with an ITO bottom electrode 2 bonded to its surface is provided;

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

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

Provide interface modification material PEI, electron transport material nano-ZnO and organic solvent ethanol, add PEI and nano-ZnO to ethanol, after mixing evenly, obtain PEI:nano-ZnO mixed solution, wherein, the concentration of PEI is 0.1wt%;

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;

Add the mixed solution dropwise on the quantum dot luminescent layer 4, and let it stand for 5 seconds. After the interface modification material 3 penetrates into the gaps of the quantum dots 41 of the quantum dot luminescent layer 4, a film is formed, and then Bake at 80°C for 5 minutes to obtain electron transport layer 5;

Under the condition of vacuum degree of 3×10 ^-4 Pa, evaporate the Al electrode at a speed of 1 Angstrom/second for 100 seconds, and the thickness of Al is 10nm;

Under the condition of a vacuum degree of 3×10 ⁻⁴ Pa, an Ag electrode was vapor-deposited at a rate of 1 Å/sec for 200 seconds, and the thickness of Ag was 20 nm to obtain a quantum dot light-emitting diode 100 .

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

Example 6

Preparation of Quantum Dot Light-Emitting Diode 100

A substrate 1 with an ITO bottom electrode 2 bonded to its surface is provided;

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

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

Provide interface modification material PEI, electron transport material nano-ZnO and organic solvent ethanol, add PEI and nano-ZnO to ethanol, after mixing evenly, obtain PEI:nano-ZnO mixed solution, wherein, the concentration of PEI is 0.1wt%;

Printing quantum dot materials on the surface of the hole transport layer to obtain a quantum dot light-emitting layer 4;

Add the mixed solution dropwise on the quantum dot luminescent layer 4, and let it stand for 5 seconds. After the interface modification material 3 penetrates into the gaps of the quantum dots 41 of the quantum dot luminescent layer 4, it is coated to form a film. Then bake at 80° C. for 5 minutes to obtain the electron transport layer 5;

Under the condition of a vacuum degree of 3×10 ⁻⁴ Pa, the Ag electrode was vapor-deposited at a rate of 1 angstrom/second for 1000 seconds, and the Ag thickness was 100 nm to obtain a quantum dot light-emitting diode 100 .

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

Example 7

Preparation of Quantum Dot Light-Emitting Diode 100

A substrate 1 with an ITO bottom electrode 2 bonded to its surface is provided;

Print the PEDOT:PSS mixed material on the ITO bottom electrode 2, and then bake at 150°C for 15 minutes to obtain the hole injection layer;

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

Provide interface modification material PEI, electron transport material nano-ZnO and organic solvent ethanol, add PEI and nano-ZnO to ethanol, after mixing evenly, obtain PEI:nano-ZnO mixed solution, wherein, the concentration of PEI is 0.1wt%;

Print quantum dot materials on the surface of the hole transport layer to obtain a quantum dot wet film, then drop the mixed solution on the surface of the quantum dot wet film, and bake at 80°C for 5 minutes after film formation to obtain a quantum dot wet film. The dot light-emitting layer 4, the transition layer 10 combined with the quantum dot light-emitting layer 4, and the electron transport layer 5 combined with the transition layer 10;

Under the condition of vacuum degree of 3×10 ^-4 Pa, evaporate the Al electrode at a speed of 1 Angstrom/second for 100 seconds, and the thickness of Al is 10nm;

Under the condition of a vacuum degree of 3×10 ⁻⁴ Pa, an Ag electrode was vapor-deposited at a rate of 1 Å/sec for 200 seconds, and the thickness of Ag was 20 nm to obtain a quantum dot light-emitting diode 100 .

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

Example 8

Preparation of Quantum Dot Light-Emitting Diode 100

A substrate 1 with an ITO bottom electrode 2 bonded to its surface is provided;

Spin-coat the PEDOT:PSS hybrid material on the ITO bottom electrode 2 at a speed of 5000r/s for 30 seconds, and then bake at 150°C for 15 minutes to obtain a hole injection layer;

Spin-coat TFB with a concentration of 8 mg/mL on the hole injection layer at a speed of 3000 r/s for 30 seconds, and then bake at 80° C. for 10 minutes to obtain a hole transport layer;

Provide interface modification material PEI, electron transport material nano-ZnO and organic solvent ethanol, add PEI and nano-ZnO to ethanol, after mixing evenly, obtain a mixed solution of PEI:nano-ZnO, wherein the concentration of PEI/PEIE is 0.1wt%;

The surface of the hole transport layer is spin-coated with a concentration of 20mg/mL quantum dot material for 30 seconds at a speed of 2000r/s, and the mixed solution is added dropwise within 2 seconds after the start of the spin coating. Baking at ℃ for 5 minutes to obtain the quantum dot light-emitting layer 4, the transition layer 10 combined with the quantum dot light-emitting layer 4, and the electron transport layer 5 combined with the transition layer 10;

Under the condition of a vacuum degree of 3×10 ⁻⁴ Pa, the Ag electrode was vapor-deposited at a rate of 1 angstrom/second for 1000 seconds, and the Ag thickness was 100 nm to obtain a quantum dot light-emitting diode 100 .

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

Comparative example 1

Fabrication of Conventional Quantum Dot Light-Emitting Diodes

A substrate with an ITO bottom electrode bonded to its surface is provided;

Print the PEDOT:PSS hybrid material on the ITO bottom electrode, and then bake at 150°C for 15min to obtain the hole injection layer;

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

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;

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

Under the condition of vacuum degree of 3×10 ^-4 Pa, evaporate the Al electrode at a speed of 1 Angstrom/second for 100 seconds, and the thickness of Al is 10nm;

Under the condition of a vacuum degree of 3×10 ^-4 Pa, an 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.

Comparative example 2

Fabrication of Conventional Quantum Dot Light-Emitting Diodes

A substrate with an ITO bottom electrode bonded to its surface is provided;

Print the PEDOT:PSS hybrid material on the ITO bottom electrode, and then bake at 150°C for 15min to obtain the hole injection layer;

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

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;

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

Under the condition of a vacuum degree of 3×10 ^-4 Pa, an Ag electrode was evaporated at a rate of 1 angstrom/second for 1000 seconds, and the Ag thickness was 20 nm to obtain a conventional quantum dot light-emitting diode.

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

The QLED JVL test method is: use Keithley2400 to apply a voltage to the quantum dot light-emitting diode from -0.6V, where the voltage step is 0.2V, and the voltage application range is -0.6V to 8V; with the application of the voltage, record the device current density and The change of luminance with voltage, the graph of the change of current density with voltage (refer to Figure 4), the graph of the change of luminance with voltage (refer to Fig. 5); the external quantum efficiency and current efficiency of the device can be obtained by calculation, and the external quantum efficiency can be obtained Efficiency-voltage curve (see Figure 6), current efficiency-voltage curve (see Figure 7).

It can be seen from Figures 5-7 that when the quantum dot light-emitting diode is prepared using the scheme of Example 1, the turn-on voltage of the device will be reduced due to the modification of PEI, and the brightness, external quantum efficiency, and current efficiency of the device will be greatly improved.

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

How QLED life test works:

The 128-channel QLED life test system controls the digital IO card of NI (National Instruments) through the PCI bus communication of the central processing computer to realize the chip selection of the number of channels and the output of digital signals, and the corresponding digital signals are converted to analog through the D/A chip. signal, complete the current output (I), and realize data acquisition through the data acquisition card. The acquisition of brightness converts the optical signal into an electrical signal through the sensor, and uses the electrical signal to simulate the brightness change (L).

QLED life test method:

Select 3-4 different constant current densities (such as 100mA/cm ² , 50mA/cm ² , 20mA/cm ² , 10mA/cm ² ), and test the initial brightness under corresponding conditions; maintain a constant current and record the brightness and the change of device voltage with time to obtain the brightness-time curve (refer to Figure 8); record the time T95, T80, T75 and T50; calculate the acceleration factor by curve fitting; extrapolate the time T for the brightness of the device to decay from 1000 nits to 95% by empirical formula, that is, the life of the device.

The empirical formula is: T=(LMA×/1000)A*T95.

Among them, LMAX is the highest brightness, and A is the acceleration factor.

The lifetime curve of the quantum dot light-emitting diode in Example 1 extrapolated by the above empirical formula is shown in FIG. 9 .

It can be seen from FIG. 9 that when the quantum dot light-emitting diode is prepared using the scheme of Example 1, the lifetime (T95) of the device will be greatly improved.

The preparation method of the quantum dot light-emitting diode provided by the embodiment of the present application has been introduced in detail above. In this paper, specific examples are used to illustrate the principle and implementation of the present application. The description of the above embodiment is only used to help understand the present application. method and its core idea; at the same time, for those skilled in the art, according to the idea of this application, there will be changes in the specific implementation and application scope. Application Restrictions.

Claims (20)

1. A method for preparing a quantum dot light-emitting diode, comprising the steps of:

   providing a substrate on which a bottom electrode is formed;

   Provide interface modification materials, electron transport materials and organic solvents, and mix them to obtain a mixed solution;

   Provide a quantum dot material, arrange the quantum dot material on the bottom electrode to form a quantum dot film, then place the mixed solution on the surface of the quantum dot film, and dry to obtain a quantum dot light-emitting layer and electron transport layer, wherein the quantum dot film is a quantum dot dry film or a quantum dot wet film;

   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 a transition layer is formed between the quantum dot luminescent layer and the electron transport layer, and the transition layer includes quantum dots, an interface modification material and an electron transport material , the interface modifying material in the transition layer is filled in 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.
3. The method for preparing quantum dot light-emitting diodes according to claim 1, wherein after disposing the mixed solution on the surface of the quantum dot film, it further includes a step of standing, and the standing time is 5-10 seconds.
4. The preparation method of quantum dot light-emitting diode as claimed in claim 1, wherein, provide quantum dot material, described quantum dot material is arranged on the described bottom electrode, forms quantum dot film, then described mixed solution is arranged on the said bottom electrode The surface of the quantum dot film, including:

   Provide quantum dot material, arrange quantum dot material on the bottom electrode, form quantum dot dry film, after obtaining quantum dot light-emitting layer, add the mixed solution on the quantum dot light-emitting layer.
5. The preparation method of quantum dot light-emitting diode as claimed in claim 1, wherein, provide quantum dot material, described quantum dot material is arranged on the described bottom electrode, forms quantum dot film, then described mixed solution is arranged on the said bottom electrode The surface of the quantum dot film, including:

   The quantum dot material is provided, and the quantum dot material is arranged on the bottom electrode to form a quantum dot wet film, and then the mixed solution is arranged on the surface of the quantum dot wet film by a solution method.
6. The preparation method of quantum dot light-emitting diode as claimed in claim 1, wherein, provide quantum dot material, described quantum dot material is arranged on the described bottom electrode, forms quantum dot film, then described mixed solution is arranged on the said bottom electrode The surface of the quantum dot film, including:

   Quantum dot material is provided, the quantum dot material is spin-coated on the bottom electrode to form a quantum dot wet film, and the mixed solution is added after the spin coating starts and before the quantum dot material forms a dry film, and the spin coating is stopped after the addition .
7. The method for preparing quantum dot light-emitting diodes according to claim 6, wherein the rotation speed of the spin coating is 2000-3000r/s, and the time range is 20-30s.
8. The method for preparing a quantum dot light-emitting diode as claimed in claim 6, wherein the time after the start of the spin coating and before the quantum dot material forms a dry film is 2-10 seconds.
9. The preparation method of quantum dot light-emitting diode as claimed in claim 1, wherein, the concentration of quantum dot in the said quantum dot material is 10-20mg/mL, and said quantum dot material is selected from CdSeZnS, CdSeCdS/ZnS or ZnCdS/ZnS .
10. The preparation method of quantum dot light-emitting diode as claimed in claim 1, wherein, said interface modification material is selected from 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 one or more of.
11. The preparation method of quantum dot light-emitting diodes as claimed in claim 1, wherein, the electron transport material is selected from metal oxides, doped metal oxides, 2-6 group semiconductor materials, 3-5 group semiconductor materials and 1- One or more of Group 3-6 semiconductor materials, the metal oxide is selected from one or more of ZnO, TiO ₂ , SnO ₂ ; the metal oxide in the doped metal oxide is selected from One or more of ZnO, TiO ₂ , SnO ₂ , the doping element is selected from one or more of aluminum, magnesium, indium, gallium; the 2-6 semiconductor group materials are selected from ZnS, ZnSe, CdS One or more of them; the 3-5 group semiconductor materials are selected from at least one of InP and GaP; the 1-3-6 group semiconductor materials are selected from at least one of CuInS and CuGaS.
12. The method for preparing quantum dot light-emitting diodes according to claim 1, wherein the organic solvent is selected from one or more of ethylene glycol monomethyl ether, isopropanol or ethanol.
13. The method for preparing quantum dot light-emitting diodes according to claim 1, wherein, in the mixed solution, the concentration range of the interface modification material is 0.1wt%-10wt%.
14. The method for preparing quantum dot light-emitting diodes according to claim 1, wherein, in the mixed solution, the concentration range of the electron transport material is 10-30 mg/mL.
15. 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 includes quantum dots, and the electron transport layer includes an electron transport material, wherein, The gaps between adjacent quantum dots and electron transport materials are filled with interface modification materials.
16. The quantum dot light-emitting diode according to claim 15, wherein, in the gap between the quantum dots on the side of the quantum dot light-emitting layer adjacent to the electron transport layer, and the gap between the electron transport materials of the electron transport layer is also filled with the interface modifying material.
17. The quantum dot light-emitting diode according to claim 15, wherein the quantum dot light-emitting diode further comprises a transition layer between the quantum dot light-emitting layer and the electron transport layer, and the transition layer includes quantum dots, interface modification materials and Electron transport material, the interface modifying material in the transition layer is 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 materials .
18. The quantum dot light-emitting diode according to claim 17, 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.
19. The quantum dot light-emitting diode according to claim 15, wherein the interface modification material is selected from polyethyleneimine, polyethoxyethyleneimine, poly[9,9-bis(3'-(N,N- One of dimethylamino)propyl)-2,7-fluorene]-2,7-(9,9-dioctylfluorene))], polyethylene glycol, conjugated polyelectrolyte or polyethylene oxide or several.
20. The quantum dot light-emitting diode according to claim 15, wherein the electron transport material is selected from metal oxides, doped metal oxides, 2-6 group semiconductor materials, 3-5 group semiconductor materials and 1-3-6 One or more of the group semiconductor materials, the metal oxide is selected from one or more of ZnO, TiO ₂ , SnO ₂ ; the metal oxide in the doped metal oxide is selected from ZnO, TiO _2. One or more of SnO ₂ , the doping element is selected from one or more of aluminum, magnesium, indium, and gallium; the 2-6 semiconductor group material is selected from one or more of ZnS, ZnSe, and CdS one or several kinds; the 3-5 semiconductor group materials are selected from at least one of InP and GaP; the 1-3-6 group semiconductor materials are selected from at least one of CuInS and CuGaS.