Quantum dot light-emitting diode, two-dimensional material and preparation method thereof

Abstract

The present invention relates to a quantum dot light-emitting diode, a two-dimensional material and a preparation method thereof. The device comprises an anode, a cathode, a quantum dot light-emitting layer disposed between the anode and the cathode, an electron transport layer disposed between the quantum dot light-emitting layer and the cathode, and an interface modification layer disposed between the cathode and the electron transport layer and in contact with the cathode; the interface modification layer comprises a metal sulfide two-dimensional material or a metal selenide two-dimensional material. The surface of the cathode is passivated by using a metal sulfide two-dimensional material or a metal selenide two-dimensional material, the cathode work function is reduced, the electron injection barrier is reduced, the electron injection and transmission are increased, the electron injection of the QLED device is promoted, and the device performance is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electroluminescence, and in particular to a quantum dot light emitting diode, a two-dimensional material and a preparation method thereof. Background Art

[0002] In recent years, with the rapid development of display technology, quantum dot light-emitting diodes (QLEDs) using semiconductor quantum dot materials as the light-emitting layer have received widespread attention. Their excellent characteristics such as high color purity, high luminous efficiency, adjustable luminous color and stable device make quantum dot light-emitting diodes have broad application prospects in the fields of flat panel display and solid-state lighting.

[0003] Although QLED has many advantages, it also has some disadvantages. For example, the cathode work function is too high, and it is difficult to extract and inject electrons from the cathode into the electron injection layer. Its surface needs to be modified to improve the mobility of electrons. In addition, the electron transport layer material in QLED is usually metal oxide. As the use time increases, the defects at the interface between the metal oxide and the cathode will increase, further increasing the electron injection barrier, thereby affecting the life of the device. Summary of the invention

[0004] Based on this, the present invention provides a technical solution that can reduce the cathode work function.

[0005] The technical solution is as follows:

[0006] A quantum dot light-emitting diode, comprising an anode, a cathode, a quantum dot light-emitting layer disposed between the anode and the cathode, an electron transport layer disposed between the quantum dot light-emitting layer and the cathode, and an interface modification layer disposed between the cathode and the electron transport layer and in contact with the cathode;

[0007] The interface modification layer comprises metal sulfide two-dimensional materials and / or metal selenide two-dimensional materials.

[0008] The present invention also provides a method for preparing a two-dimensional material, comprising the following steps:

[0009] Dissolving a first metal halide and an organic compound in a first organic solvent to prepare a first mixed solution, and preparing the two-dimensional material by a solvothermal method;

[0010] The organic compound is an organic sulfur compound, and the corresponding two-dimensional material prepared is a metal sulfide two-dimensional material; the organic compound is an organic selenium compound, and the corresponding two-dimensional material prepared is a metal selenide two-dimensional material.

[0011] The present invention also provides a method for preparing a quantum dot light-emitting diode, comprising the step of preparing an interface modification layer containing a two-dimensional material between a cathode and an electron transport layer, wherein the preparation of the interface modification layer containing the two-dimensional material comprises the following steps:

[0012] The two-dimensional material is prepared by the method for preparing the two-dimensional material as described above;

[0013] The two-dimensional material is a metal sulfide two-dimensional material and / or a metal selenide two-dimensional material.

[0014] The present invention has the following beneficial effects:

[0015] In the present invention, metal sulfide or metal selenide two-dimensional materials are used to passivate the surface of the cathode, reduce the cathode work function, lower the electron injection barrier, increase the injection and transmission of cathode electrons, promote electron injection of QLED devices, and improve device performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of an inverted QLED device according to an embodiment of the present invention;

[0017] Figure 2 is a schematic structural diagram of an inverted QLED device according to another embodiment of the present invention;

[0018] Figure 3 is a schematic structural diagram of an inverted QLED device according to another embodiment of the present invention;

[0019] Figure 4 is a schematic structural diagram of an inverted QLED device according to another embodiment of the present invention;

[0020] Figure 5 is a schematic structural diagram of an inverted QLED device according to another embodiment of the present invention;

[0021] Figure 6 is a schematic structural diagram of an inverted QLED device according to another embodiment of the present invention;

[0022] Figure 7 is a schematic structural diagram of an inverted QLED device according to another embodiment of the present invention;

[0023] Figure 8 is a schematic structural diagram of an inverted QLED device according to another embodiment of the present invention;

[0024] Fig. 9 is a schematic structural diagram of a normal QLED device according to an embodiment of the present invention;

[0025] Fig.10is a flow chart of a method for preparing a metal sulfide two-dimensional material according to an embodiment of the present invention;

[0026] Fig.11 is a flow chart of a method for preparing a metal selenide two-dimensional material according to an embodiment of the present invention;

[0027] Fig.12 An embodiment of the present invention is about Figure 5 A flow chart of a method for preparing an inverted QLED device;

[0028] Fig.13 An embodiment of the present invention is about Figure 6 A flow chart of a method for preparing an inverted QLED device;

[0029] Fig.14 An embodiment of the present invention is about Figure 7 A flow chart of a method for preparing an inverted QLED device;

[0030] Fig.15 An embodiment of the present invention is about Figure 8 A flow chart of a method for preparing an inverted QLED device;

[0031] Fig.16 An embodiment of the present invention is about Fig. 9 Flow chart of the preparation method of an upright QLED device. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and effect of the present invention clearer and more specific, the present invention is further described in detail below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0034] When describing positional relationships, unless otherwise specified, when an element such as a layer, film, or substrate is referred to as being "on" another film layer, it can be directly on the other film layer or there can be an intermediate film layer. Further, when a layer is referred to as being "under" another layer, it can be directly below or there can be one or more intermediate layers. It is also understood that when a layer is referred to as being "between" two layers, it can be the only layer between the two layers, or there can be one or more intermediate layers.

[0035] Where “including,” “having,” and “comprising” are used herein, it is intended to cover a non-exclusive inclusion, and another component may also be added unless explicit limiting terms such as “only,” “consisting of,” etc. are used.

[0036] Unless mentioned to the contrary, terms in the singular may include plural forms and should not be construed as being one in number.

[0037] In addition, the drawings are not drawn in a 1:1 ratio, and the relative sizes of the elements are drawn in the drawings only as examples to facilitate understanding of the present invention, but are not necessarily drawn in true proportion. The proportions in the drawings do not constitute a limitation to the present invention.

[0038] The invention provides a technical solution capable of reducing the cathode work function.

[0039] The technical solution is as follows:

[0040] The quantum dot light-emitting diode provided by the present invention comprises an anode, a cathode, a quantum dot light-emitting layer arranged between the anode and the cathode, an electron transport layer arranged between the quantum dot light-emitting layer and the cathode, and an interface modification layer arranged between the cathode and the electron transport layer and in contact with the cathode; the interface modification layer comprises metal sulfide and / or metal selenide two-dimensional materials.

[0041] The present invention uses metal sulfide two-dimensional materials and / or metal selenide two-dimensional materials to passivate the surface of the cathode, reduce the cathode work function, lower the electron injection barrier, increase the injection and transmission of cathode electrons, promote electron injection of QLED devices, and improve device performance.

[0042] In one embodiment, the metal sulfide is tin disulfide or tungsten disulfide, and the metal selenide is tin diselenide or indium selenide. The use of such metal sulfides or metal selenides can better reduce the cathode work function, reduce the electron injection barrier, increase the injection and transmission of electrons, promote the electron injection of QLED devices, and improve device performance. In addition, these two-dimensional materials have a large specific surface area and a large contact surface at the interface. A suitable heterojunction interface system can be constructed through the metal oxides of these metals, which further promotes the migration of carriers, is conducive to enhancing the electrical properties of these metal oxides, and improving device performance; if a hollow microsphere layer containing perovskite composite metal oxides is added, the heterojunction interface system constructed by the metal oxides is also conducive to enhancing the electrical properties of the perovskite composite metal oxides, and further improving device performance.

[0043] In one embodiment, the metal sulfide is tin disulfide; the metal selenide is tin diselenide or indium selenide.

[0044] It can be understood that in the present invention, the quantum dot light emitting diode can be an upright QLED or an inverted QLED.

[0045] In one embodiment of the present invention, the quantum dot light-emitting diode is an inverted QLED. At present, the preparation of QLED screens can be mainly prepared by inkjet printing and evaporation. The preparation of inverted QLED devices only requires printing an electron transport layer (such as ZnO) and a QD light-emitting layer on a cathode (such as ITO). Other hole transport layers, hole injection layers, and anode layers can all be prepared using mature evaporation conditions in the preparation of OLED devices, which makes inverted QLED devices have great commercial prospects.

[0046] Taking the inverted QLED as an example, the schematic diagram of the QLED structure including an interface modification layer is shown in FIG. Figure 1 The inverted QLED includes a cathode 101, an interface modification layer 102, an electron transport layer 103, a quantum dot light-emitting layer 104 and an anode 105; the interface modification layer 102 includes a metal sulfide or metal selenide two-dimensional material.

[0047] In one embodiment, the interface modification layer of the quantum dot light-emitting diode of the present invention includes a first interface modification layer and a second interface modification layer stacked, the first interface modification layer is close to the cathode, and the second interface modification layer is close to the electron transport layer; the first interface modification layer contains a metal sulfide two-dimensional material or a metal selenide two-dimensional material; the second interface modification layer contains a metal oxide, and the metal element in the metal oxide is the same as the metal element in the metal sulfide or metal selenide. The use of a specific first interface modification layer and a metal oxide to construct a heterojunction interface system can further reduce the electron injection barrier, suppress excess holes, and further promote the migration of carriers, which is conducive to enhancing the electrical properties of these metal oxides.

[0048] In one embodiment, the metal oxide is tin oxide, tungsten trioxide, tungsten pentoxide or indium oxide.

[0049] Taking the inverted QLED as an example, the schematic diagram of the QLED structure including two layers of interface modification layers can be found in Figure 2 The inverted QLED includes a cathode 201, a first interface modification layer 2021, a second interface modification layer 2022, an electron transport layer 203, a quantum dot light-emitting layer 204 and an anode 205, wherein the first interface modification layer 2021 comprises a metal sulfide two-dimensional material or a metal selenide two-dimensional material; the second interface modification layer 2022 comprises a metal oxide, and the metal element in the metal oxide is the same as the metal element in the metal sulfide or the metal selenide.

[0050] In one embodiment, the interface modification layer of the quantum dot light-emitting diode of the present invention includes a first interface modification layer and a second interface modification layer which are stacked, the first interface modification layer is close to the cathode, and the second interface modification layer is close to the electron transport layer; the first interface modification layer comprises a metal sulfide two-dimensional material or a metal selenide two-dimensional material; the second interface modification layer comprises a perovskite composite metal oxide hollow microsphere. The use of a specific first interface modification layer, coupled with a perovskite composite metal oxide hollow microsphere interlayer, can reduce the defects of the first interface modification layer and the electron transport layer, can effectively shorten the carrier transmission path, and make the electron transport layer fully contact with the first interface modification layer, improve the extraction and transmission of electrons, and thus can improve the efficiency and carrier balance of the device, and improve the life and stability of the device.

[0051] In one embodiment, the perovskite composite metal oxide is zinc metastannate, zinc titanate, barium titanate or zinc cobaltate.

[0052] Taking the inverted QLED as an example, the schematic diagram of the QLED structure including two layers of interface modification layers can be found in Figure 3 The inverted QLED includes a cathode 301, a first interface modification layer 3021, a second interface modification layer 3022, an electron transport layer 303, a quantum dot light-emitting layer 304 and an anode 305. The first interface modification layer 3021 contains a metal sulfide two-dimensional material or a metal selenide two-dimensional material; the second interface modification layer 3022 contains perovskite composite metal oxide hollow microspheres.

[0053] In one embodiment, the interface modification layer of the quantum dot light-emitting diode of the present invention includes a first interface modification layer, a second interface modification layer and a third interface modification layer which are stacked, wherein the first interface modification layer is close to the cathode, and the third interface modification layer is close to the electron transport layer; the first interface modification layer comprises a metal sulfide or metal selenide two-dimensional material; the second interface modification layer comprises a metal oxide, and the metal element in the metal oxide is the same as the metal element in the metal sulfide or metal selenide; the third interface modification layer comprises a perovskite composite metal oxide hollow microsphere. The use of a specific first interface modification layer and a metal oxide to construct a heterojunction interface system can further promote the migration of carriers, which is conducive to enhancing the electrical properties of metal oxides and perovskite composite metal oxides, and the perovskite composite metal oxide hollow microsphere interlayer can reduce the defects of the second interface modification layer and the electron transport layer, can effectively shorten the carrier transmission path, and make the electron transport layer fully contact with the second interface modification layer, improve the extraction and transmission of electrons, and thus improve the efficiency and carrier balance of the device, and improve the life and stability of the device.

[0054] Taking the inverted QLED as an example, the schematic diagram of the QLED structure including the three layers of interface modification layers can be found in Figure 4 The inverted QLED includes a cathode 401, a first interface modification layer 4021, a second interface modification layer 4022, a third interface modification layer 4023, an electron transport layer 403, a quantum dot light-emitting layer 404 and an anode 405, wherein the first interface modification layer comprises a metal sulfide or metal selenide two-dimensional material; the second interface modification layer comprises a metal oxide, and the metal element in the metal oxide is the same as the metal element in the metal sulfide or metal selenide; the third interface modification layer comprises perovskite composite metal oxide hollow microspheres.

[0055] In one embodiment, the anode of the present invention is selected from at least one of ITO, Ag or Al.

[0056] In one embodiment, the cathode in the present invention is selected from at least one of ITO, IZO, FTO (fluorine-doped tin oxide), and Al. The cathode is passivated with a two-dimensional material to reduce the cathode work function. Taking ITO as an example, according to the scheme of the present invention, the ITO electrode is passivated with a two-dimensional material to reduce the ITO work function, so that the ITO work function is reduced from 4.6eV to about 4.4eV.

[0057] The electron transport layer material in QLED is usually metal oxide. As the use time increases, the defects at the interface between the metal oxide and the cathode will increase, further increasing the electron injection barrier, thereby affecting the life of the device.

[0058] In one embodiment, the electron transport material of the present invention is selected from at least one of zinc oxide, barium oxide or titanium oxide.

[0059] In one embodiment, the cathode of the present invention comprises an ITO layer, the electron transport layer is zinc oxide, and the ITO layer and the zinc oxide are arranged close to each other. According to the scheme of the present invention, the ITO work function can be reduced from 4.6eV to about 4.4eV, which is closer to the LUMO energy level of 3.5eV of the zinc oxide electron transport layer, thereby promoting the injection of electrons and improving the device performance.

[0060] In one embodiment, the quantum dot light-emitting layer described in the present invention is a quantum dot light-emitting material with a core-shell structure, such as one or more of Group II-VI compounds, Group III-V compounds, Group II-V compounds, Group III-VI compounds, Group IV-VI compounds, Group I-III-VI compounds, Group II-IV-VI compounds or Group IV elements, the core material may be but is not limited to at least one selected from CdSe, CdS, ZnSe, ZnS, CdTe, CdZnS, CdZnSe, ZnSeS, ZnSeTe, ZnTeS, CdSeS, CdSeTe, CdTeS, CdZnSeS, CdZnSeTe, CdZnSTe, CdSeSTe, ZnSeSTe, CdZnSeSTe, InP, InAs, InAsP, and the shell material may be but is not limited to at least one selected from CdS, ZnSe, ZnS, CdSeS and ZnSeS. The use of such quantum dots has higher luminescence performance, but is not limited to core-shell quantum dots such as CdSe / ZnS, CdS / ZnSe, CdZnS / ZnSe, or quantum dot materials based on gradient shells.

[0061] In one embodiment, the quantum dot light-emitting diode of the present invention further includes a hole transport layer and a hole injection layer. The addition of these two layers is more conducive to carrier balance and further improves device performance.

[0062] In one embodiment, the materials used to prepare the hole injection layer include but are not limited to: PEDOT:PSS, NiOx, WO3, CuPc, HATCN, m-MTDATA, F4-TCQN and MoO3.

[0063] In one embodiment, the material used to prepare the hole transport layer includes but is not limited to: TPD, poly-TPD, PVK, CBP, NPB, TCTA, mCP, TAPC NiOx and TFB and their composites.

[0064] The schematic diagram of the inverted QLED structure including an interface modification layer, a hole transport layer and a hole injection layer is shown in FIG. Figure 5 The inverted QLED of the present invention includes a cathode 501, an interface modification layer 502, an electron transport layer 503, a quantum dot light-emitting layer 504, a hole transport layer 505, a hole injection layer 506 and an anode 507 which are stacked in sequence, and the interface modification layer 502 contains a metal sulfide or metal selenide two-dimensional material.

[0065] The schematic diagram of the inverted QLED structure including two interface modification layers, a hole transport layer and a hole injection layer is shown in Figure 6The inverted QLED of the present invention includes a cathode 601, a first interface modification layer 6021, a second interface modification layer 6022, an electron transport layer 603, a quantum dot light-emitting layer 604, a hole transport layer 605, a hole injection layer 606 and an anode 607 which are stacked in sequence. The first interface modification layer 6021 includes a metal sulfide or metal selenide two-dimensional material, and the second interface modification layer 6022 includes a metal oxide, and the metal element in the metal oxide is the same as the metal element in the metal sulfide or metal selenide.

[0066] The schematic diagram of the inverted QLED structure including two interface modification layers, a hole transport layer and a hole injection layer is shown in Figure 7 The inverted QLED of the present invention includes a cathode 701, a first interface modification layer 7021, a second interface modification layer 7022, an electron transport layer 703, a quantum dot light-emitting layer 704, a hole transport layer 705, a hole injection layer 706 and an anode 707 which are stacked in sequence. The first interface modification layer 7021 includes a metal sulfide or metal selenide two-dimensional material, and the second interface modification layer 7022 includes perovskite composite metal oxide hollow microspheres.

[0067] The schematic diagram of the inverted QLED structure including three layers of interface modification layer, hole transport layer and hole injection layer is shown in Figure 8 The inverted QLED of the present invention includes a cathode 801, a first interface modification layer 8021, a second interface modification layer 8022, a third interface modification layer 8023, an electron transport layer 803, a quantum dot light-emitting layer 804, a hole transport layer 805, a hole injection layer 806 and an anode 807 which are stacked in sequence, the first interface modification layer 8021 includes a metal sulfide or metal selenide two-dimensional material, the second interface modification layer 8022 includes a metal oxide, the metal element in the metal oxide is the same as the metal element in the metal sulfide or metal selenide, and the third interface modification layer 8023 includes perovskite composite metal oxide hollow microspheres.

[0068] The schematic diagram of the structure of the upright QLED including three layers of interface modification layer, hole transport layer and hole injection layer is shown in Fig. 9 The upright QLED of the present invention includes an anode 901, a hole injection layer 902, a hole transport layer 903, a quantum dot light-emitting layer 904, an electron transport layer 905, a third interface modification layer 9063, a second interface modification layer 9062, a first interface modification layer 9061 and a cathode 907 which are stacked in sequence. The first interface modification layer 9061 includes a metal sulfide or metal selenide two-dimensional material, the second interface modification layer 9062 includes a metal oxide, the metal element in the metal oxide is the same as the metal element in the metal sulfide or metal selenide, and the third interface modification layer 9063 includes perovskite composite metal oxide hollow microspheres.

[0069] In one embodiment, the thickness ratio of the first interface modification layer of the present invention and the second interface modification layer containing the metal oxide is (0.6-5):1. Controlling the thickness of the two can not only reduce the cathode work function, but also help the interface modification layer to suppress excess holes. If the second interface modification layer containing the metal oxide is too thick, the first interface modification layer containing the two-dimensional material will be too thin, which will not be able to reduce the cathode work function and cover the roughness of the cathode film. Furthermore, the thickness ratio of the first interface modification layer of the present invention and the second interface modification layer containing the metal oxide is (1.5-5):1.

[0070] In one embodiment, the thickness of the first interface modification layer is 4nm to 10nm, and the thickness of the second interface modification layer containing the metal oxide is 2nm to 6nm. Further, the thickness of the first interface modification layer is 6nm to 10nm, and the thickness of the second interface modification layer containing the metal oxide is 2nm to 4nm.

[0071] In one embodiment, the thickness of the second interface modification layer containing the perovskite composite metal oxide hollow microspheres is 10nm to 15nm, or the thickness of the third interface modification layer containing the perovskite composite metal oxide hollow microspheres is 10nm to 15nm. By controlling the thickness of the perovskite composite metal oxide interlayer, the purpose of controlling the carrier transmission path and the contact surface between the electron transport layer and the first interface modification layer, or the purpose of the contact surface between the electron transport layer and the second interface modification layer containing the metal oxide is achieved, so as to achieve the effect of improving the extraction and transmission of electrons.

[0072] In one embodiment, the outer diameter of the perovskite composite metal oxide hollow microspheres is 5 nm to 8 nm, and the inner diameter is 3 nm to 4 nm.

[0073] In one embodiment, the thickness of the cathode in the upright QLED and / or the inverted QLED is 20-200 nm.

[0074] In one embodiment, the thickness of the electron transport layer in the upright QLED and / or the inverted QLED is 20-100 nm.

[0075] In one embodiment, the thickness of the quantum dot light-emitting layer in the upright QLED and / or the inverted QLED is 10 to 100 nm.

[0076] In one embodiment, the thickness of the hole transport layer in the upright QLED and / or the inverted QLED is 30-40 nm.

[0077] In one embodiment, the thickness of the hole injection layer in the upright QLED and / or the inverted QLED is 20-40 nm.

[0078] In one embodiment, the thickness of the anode in the upright QLED and / or the inverted QLED is 20-200 nm.

[0079] The present invention also provides a method for preparing a two-dimensional material, comprising the following steps:

[0080] Dissolving a first metal halide and an organic compound in a first organic solvent to prepare a first mixed solution, and preparing a two-dimensional material by a solvothermal method;

[0081] The organic compound is an organic sulfur compound, and the corresponding two-dimensional material is a metal sulfide two-dimensional material;

[0082] The organic compound is an organic selenium compound, and the corresponding two-dimensional material is a metal selenide two-dimensional material.

[0083] Specifically, the preparation method of the metal sulfide two-dimensional material provided by the present invention is as follows: Fig.10 , including the following steps:

[0084] A first metal halide and an organic sulfur compound are dissolved in a first organic solvent to prepare a first mixed solution, and a metal sulfide two-dimensional material is prepared by a solvothermal method.

[0085] In one embodiment, the first metal halide is a metal chloride, and the organic sulfur compound is an amide sulfide. Furthermore, the organic sulfur compound is thioacetamide.

[0086] In one embodiment, the molar ratio of the first metal halide to the organic sulfur compound is 1:(1-5).

[0087] In one embodiment, the first organic solvent is an alcohol organic solvent.

[0088] Specifically, the preparation method of the metal selenide two-dimensional material provided by the present invention is as follows Fig.11 , including the following steps:

[0089] The first metal halide and the organic selenium compound are dissolved in a first organic solvent to prepare a second mixed solution, and the metal selenide two-dimensional material is prepared by a solvothermal method.

[0090] In one embodiment, the first metal halide is a metal chloride, and the organic selenium compound is an amide selenide. Furthermore, the organic selenium compound is selenoacetamide.

[0091] In one embodiment, the molar ratio of the first metal halide to the organic selenium compound is 1:(1-5).

[0092] In one embodiment, the first organic solvent is an alcohol organic solvent.

[0093] It can be understood that if the metal sulfide two-dimensional material or metal selenide two-dimensional material prepared by the present invention is applied to a quantum dot light-emitting device, the above-mentioned two-dimensional material can be prepared first, and then the above-mentioned two-dimensional material can be deposited between the cathode and the electron transport layer by vapor deposition (such as evaporation or sputtering) or solution method (inkjet printing, spin coating). The two-dimensional material can also be prepared directly between the cathode and the electron transport layer by a solvothermal method during the preparation of the quantum dot light-emitting device.

[0094] The present invention also provides a method for preparing the metal oxide contained in the second interface modification layer, referring to the following two methods.

[0095] (1) The method for preparing the metal oxide of the present invention comprises the following steps:

[0096] First, a metal sulfide two-dimensional material or a metal selenide two-dimensional material is prepared by the preparation method of the metal sulfide two-dimensional material or the metal selenide two-dimensional material provided by the present invention, and then the two-dimensional material is annealed and oxidized at 400°C to 500°C in an oxygen-containing, protective gas atmosphere to obtain a metal oxide.

[0097] In one embodiment, the flow rate of oxygen is 5 sccm to 10 sccm, the oxidation time is 2 h to 3 h, and the thickness ratio of the unoxidized two-dimensional material to the oxidized two-dimensional material is (1.5 to 5):1.

[0098] (2) The third metal chloride is hydrolyzed at 120° C. to 250° C. under alkaline conditions to obtain a metal oxide. Further, the metal element in the third metal chloride is tin, tungsten or indium.

[0099] In one embodiment, the hydrolysis treatment time is 10 hours to 20 hours, and the pH value of the reaction system is 8 to 11. Furthermore, the reagent for adjusting the pH of the system is hexadecyltrimethylammonium bromide.

[0100] It can be understood that if the metal oxide prepared by the present invention is applied to a quantum dot light-emitting device, 1) the metal oxide can be deposited on the electron transport layer or the third interface modification layer containing the hollow microspheres of the perovskite composite metal oxide by vapor deposition (such as evaporation or sputtering) or solution method (inkjet printing, spin coating). 2) If it is an inverted QLED device, and the first interface modification layer containing the two-dimensional material is first prepared, the two-dimensional material in the first interface modification layer can be directly annealed and oxidized, without the need to use additional vapor deposition or solution method to deposit the metal oxide.

[0101] The present invention also provides a method for preparing perovskite composite metal oxide hollow microspheres, comprising the following steps:

[0102] Dissolving several different metal compounds and a first base in a first solvent to prepare a first base solution;

[0103] dissolving a second base in a second solvent to prepare a second base solution;

[0104] The second alkaline solution is added to the first alkaline solution for reflux reaction.

[0105] In one embodiment, the metal compound is at least two of tin disulfide, indium disulfide and dock disulfide.

[0106] In one embodiment, the first base is selected from at least one of zinc nitrate, tin chloride, indium chloride and sodium hydroxide.

[0107] In one embodiment, the second base is selected from at least one of sodium hydroxide, sodium methoxide and potassium hydroxide.

[0108] In one embodiment, the first base and the second base are of the same type, both sodium hydroxide.

[0109] In one embodiment, the first solvent and the second solvent are both a mixed solvent of alcohol and water. The reflux reaction temperature is related to the solvent composition and can be adjusted according to the solvent composition.

[0110] In one embodiment, in the first solvent, the volume ratio of alcohol to water is (0.1-10):1.

[0111] In one embodiment, in the second solvent, the volume ratio of alcohol to water is (0.1-10):1.

[0112] It can be understood that if the perovskite composite metal oxide hollow microspheres prepared by the present invention are applied to quantum dot light-emitting devices, they can be deposited on the electron transport layer, or on the second interface modification layer containing metal oxide, or on the first interface modification layer containing two-dimensional materials by a solution method (such as inkjet printing, spin coating).

[0113] The present invention also provides a method for preparing a quantum dot light-emitting diode, comprising the step of preparing an interface modification layer containing a metal sulfide between a cathode and an electron transport layer, wherein the preparation of the interface modification layer containing a metal sulfide two-dimensional material comprises the following steps:

[0114] The metal sulfide two-dimensional material is prepared by the method for preparing the metal sulfide two-dimensional material as described above; and / or

[0115] The method for preparing a quantum dot light-emitting diode comprises the steps of preparing an interface modification layer containing a metal selenide two-dimensional material between a cathode and an electron transport layer, and the preparation of the interface modification layer containing a metal selenide two-dimensional material comprises the following steps:

[0116] The metal sulfide two-dimensional material is prepared by the preparation method of the metal sulfide two-dimensional material as described above.

[0117] See also Fig.12 , for structures such as Figure 5 The inverted structure QLED device shown in the figure has a preparation method comprising the following steps:

[0118] providing a cathode;

[0119] On the cathode, a metal sulfide two-dimensional material or a metal selenide two-dimensional material is prepared according to the preparation method of the metal sulfide two-dimensional material and / or the metal selenide two-dimensional material of the present invention to prepare an interface modification layer;

[0120] preparing an electron transport layer on the interface modification layer;

[0121] preparing a quantum dot light-emitting layer on the electron transport layer;

[0122] preparing a hole transport layer on the quantum dot light-emitting layer;

[0123] preparing a hole injection layer on the hole transport layer;

[0124] An anode is prepared on the hole injection layer.

[0125] In one embodiment, the Figure 5The hole transport layer, hole injection layer, quantum dot light-emitting layer and electron transport layer in the inverted structure QLED device shown, the solution method is inkjet printing, dip coating or spin coating, the vapor deposition method is evaporation or magnetron sputtering, and the evaporation rate is 0.1nm / s~0.3nm / s; the anode is prepared by a vapor deposition method, such as evaporation, and the evaporation rate is 1nm / s~3nm / s.

[0126] In one embodiment, for a structure such as Figure 5 The inverted structure QLED device shown in the figure has a preparation method comprising the following steps:

[0127] providing a cathode;

[0128] On the cathode, a metal sulfide two-dimensional material or a metal selenide two-dimensional material is prepared according to the preparation method of the metal sulfide two-dimensional material or the metal selenide two-dimensional material of the present invention to prepare an interface modification layer;

[0129] preparing an electron transport layer on the interface modification layer by inkjet printing;

[0130] preparing a quantum dot light-emitting layer on the electron transport layer by inkjet printing;

[0131] preparing a hole transport layer on the quantum dot light-emitting layer by inkjet printing;

[0132] preparing a hole injection layer on the hole transport layer by inkjet printing;

[0133] The anode was prepared on the hole transport layer by evaporation.

[0134] It can be understood that for an inverted QLED device in which the first interface modification layer comprises a metal sulfide two-dimensional material and / or a metal selenide two-dimensional material; and the second interface modification layer adjacent thereto comprises a metal oxide, and the metal element in the metal oxide is the same as the metal element in the metal sulfide or metal selenide, the first interface modification layer is prepared first, and then the second interface modification layer is prepared, so the metal oxide can be directly prepared using the two-dimensional material in the first interface modification layer as the starting material.

[0135] See also Fig.13 , for structures such as Figure 6 The inverted structure QLED device shown in the figure has a preparation method comprising the following steps:

[0136] providing a cathode;

[0137] On the cathode, a metal sulfide two-dimensional material or a metal selenide two-dimensional material is prepared according to the preparation method of the metal sulfide two-dimensional material or the metal selenide two-dimensional material of the present invention to prepare a first interface modification layer;

[0138] Under the conditions of 400° C. to 500° C. and an oxygen-containing, protective gas atmosphere (such as argon or nitrogen), the two-dimensional material in the first interface modification layer is annealed, and a portion of the two-dimensional material is exposed to oxygen for oxidation treatment, so as to prepare a second interface modification layer containing a metal oxide on the first interface modification layer;

[0139] preparing an electron transport layer on the second interface modification layer;

[0140] preparing a quantum dot light-emitting layer on the electron transport layer;

[0141] preparing a hole transport layer on the quantum dot light-emitting layer;

[0142] preparing a hole injection layer on the hole transport layer;

[0143] An anode is prepared on the hole injection layer.

[0144] In one embodiment, the Figure 6 The hole transport layer, hole injection layer, quantum dot light-emitting layer and electron transport layer in the inverted structure QLED device shown, the solution method is inkjet printing, dip coating or spin coating, the vapor deposition method is evaporation or sputtering, and the evaporation rate is 0.1nm / s~0.3nm / s; the anode is prepared by a vapor deposition method, such as evaporation, and the evaporation rate is 1nm / s~3nm / s.

[0145] In one embodiment, for a structure such as Figure 6 The inverted structure QLED device shown in the figure has a preparation method comprising the following steps:

[0146] providing a cathode;

[0147] On the cathode, a metal sulfide two-dimensional material or a metal selenide two-dimensional material is prepared according to the preparation method of the metal sulfide two-dimensional material or the metal selenide two-dimensional material of the present invention to prepare a first interface modification layer;

[0148] Under the conditions of 400° C. to 500° C. and an oxygen-containing, protective gas atmosphere (such as argon or nitrogen), the two-dimensional material in the first interface modification layer is annealed, and a portion of the two-dimensional material is exposed to oxygen for oxidation treatment, so as to prepare a second interface modification layer containing a metal oxide on the first interface modification layer;

[0149] preparing an electron transport layer on the second interface modification layer by inkjet printing;

[0150] preparing a quantum dot light-emitting layer on the electron transport layer by inkjet printing;

[0151] preparing a hole transport layer on the quantum dot light-emitting layer by inkjet printing;

[0152] preparing a hole injection layer on the hole transport layer by inkjet printing;

[0153] The anode was prepared on the hole transport layer by evaporation.

[0154] See also Fig.14 , for structures such as Figure 7 The inverted structure QLED device shown in the figure has a preparation method comprising the following steps:

[0155] providing a cathode;

[0156] On the cathode, a metal sulfide two-dimensional material or a metal selenide two-dimensional material is prepared according to the preparation method of the metal sulfide two-dimensional material or the metal selenide two-dimensional material of the present invention to prepare a first interface modification layer;

[0157] Dissolving several different metal compounds and a first base in a first solvent to prepare a first base solution;

[0158] dissolving a second base in a second solvent to prepare a second base solution;

[0159] Adding the second alkaline solution to the first alkaline solution, refluxing the solution to prepare hollow microspheres containing perovskite composite metal oxides, and depositing the hollow microspheres containing perovskite composite metal oxides on the first interface modification layer by a solution method to prepare a second interface modification layer;

[0160] preparing an electron transport layer on the second interface modification layer;

[0161] preparing a quantum dot light-emitting layer on the electron transport layer;

[0162] preparing a hole transport layer on the quantum dot light-emitting layer;

[0163] preparing a hole injection layer on the hole transport layer;

[0164] An anode is prepared on the hole injection layer.

[0165] In one embodiment, the Figure 7 The hole transport layer, hole injection layer, quantum dot light-emitting layer and electron transport layer in the inverted structure QLED device shown, the solution method is inkjet printing, dip coating or spin coating, the vapor deposition method is evaporation or magnetron sputtering, and the evaporation rate is 0.1nm / s~0.3nm / s; the anode is prepared by a vapor deposition method, such as evaporation, and the evaporation rate is 1nm / s~3nm / s.

[0166] In one embodiment, for a structure such as Figure 7 The inverted structure QLED device shown in the figure has a preparation method comprising the following steps:

[0167] providing a cathode;

[0168] On the cathode, a metal sulfide two-dimensional material or a metal selenide two-dimensional material is prepared according to the preparation method of the metal sulfide two-dimensional material or the metal selenide two-dimensional material of the present invention to prepare a first interface modification layer;

[0169] Dissolving several different metal compounds and a first base in a first solvent to prepare a first base solution;

[0170] dissolving a second base in a second solvent to prepare a second base solution;

[0171] Adding the second alkaline solution to the first alkaline solution, refluxing the solution to prepare hollow microspheres containing perovskite composite metal oxides, and depositing the hollow microspheres containing perovskite composite metal oxides on the first interface modification layer by a solution method to prepare a second interface modification layer;

[0172] preparing an electron transport layer on the second interface modification layer by inkjet printing;

[0173] preparing a quantum dot light-emitting layer on the electron transport layer by inkjet printing;

[0174] preparing a hole transport layer on the quantum dot light-emitting layer by inkjet printing;

[0175] preparing a hole injection layer on the hole transport layer by inkjet printing;

[0176] The anode was prepared on the hole transport layer by evaporation.

[0177] See also Fig.15 , for structures such as Figure 8 The inverted structure QLED device shown in the figure has a preparation method comprising the following steps:

[0178] providing a cathode;

[0179] On the cathode, a metal sulfide two-dimensional material or a metal selenide two-dimensional material is prepared according to the preparation method of the metal sulfide two-dimensional material or the metal selenide two-dimensional material of the present invention to prepare a first interface modification layer;

[0180] Under the conditions of 400° C. to 500° C. and an oxygen-containing, protective gas atmosphere (such as argon or nitrogen), the two-dimensional material in the first interface modification layer is annealed, and a portion of the two-dimensional material is exposed to oxygen for oxidation treatment, so as to prepare a second interface modification layer containing a metal oxide on the first interface modification layer;

[0181] Dissolving several different metal compounds and a first base in a first solvent to prepare a first base solution;

[0182] dissolving a second base in a second solvent to prepare a second base solution;

[0183] adding the second alkaline solution to the first alkaline solution, refluxing the solution to prepare hollow microspheres containing perovskite composite metal oxides, and depositing the hollow microspheres containing perovskite composite metal oxides on the second interface modification layer by a solution method to prepare a third interface modification layer;

[0184] preparing an electron transport layer on the third interface modification layer;

[0185] preparing a quantum dot light-emitting layer on the electron transport layer;

[0186] preparing a hole transport layer on the quantum dot light-emitting layer;

[0187] preparing a hole injection layer on the hole transport layer;

[0188] An anode is prepared on the hole injection layer.

[0189] In one embodiment, the Figure 8 The hole transport layer, hole injection layer, quantum dot light-emitting layer and electron transport layer in the inverted structure QLED device shown, the solution method is inkjet printing, dip coating or spin coating, the vapor deposition method is evaporation or magnetron sputtering, and the evaporation rate is 0.1nm / s~0.3nm / s; the anode is prepared by a vapor deposition method, such as evaporation, and the evaporation rate is 1nm / s~3nm / s.

[0190] In one embodiment, for a structure such as Figure 8 The inverted structure QLED device shown in the figure has a preparation method comprising the following steps:

[0191] providing a cathode;

[0192] On the cathode, a metal sulfide two-dimensional material or a metal selenide two-dimensional material is prepared according to the preparation method of the metal sulfide two-dimensional material or the metal selenide two-dimensional material of the present invention to prepare a first interface modification layer;

[0193] Under the conditions of 400° C. to 500° C. and an oxygen-containing, protective gas atmosphere (such as argon or nitrogen), the two-dimensional material in the first interface modification layer is annealed, and a portion of the two-dimensional material is exposed to oxygen for oxidation treatment, so as to prepare a second interface modification layer containing a metal oxide on the first interface modification layer;

[0194] Dissolving several different metal compounds and a first base in a first solvent to prepare a first base solution;

[0195] dissolving a second base in a second solvent to prepare a second base solution;

[0196] adding the second alkaline solution to the first alkaline solution, refluxing the solution to prepare hollow microspheres containing perovskite composite metal oxides, and depositing the hollow microspheres containing perovskite composite metal oxides on the second interface modification layer by a solution method to prepare a third interface modification layer;

[0197] preparing an electron transport layer on the third interface modification layer;

[0198] preparing a quantum dot light-emitting layer on the electron transport layer by inkjet printing;

[0199] preparing a hole transport layer on the quantum dot light-emitting layer by inkjet printing;

[0200] preparing a hole injection layer on the hole transport layer by inkjet printing;

[0201] The anode was prepared on the hole transport layer by evaporation.

[0202] It can be understood that for a first interface modification layer comprising a metal sulfide-type two-dimensional material and / or a metal selenide-type two-dimensional material; and an adjacent second interface modification layer comprising a metal oxide, and the metal element in the metal oxide is the same as the metal element in the metal sulfide or metal selenide, for a positive QLED device, the second interface modification layer is prepared first, and then the first interface modification layer is prepared, so it is difficult to prepare the metal oxide directly using the two-dimensional material in the first interface modification layer as the starting material. Therefore, the metal oxide can be prepared separately first and then deposited on the electron transport layer or on the third interface modification layer comprising perovskite composite metal oxide hollow microspheres by vapor deposition (such as evaporation) or solution method (inkjet printing, spin coating).

[0203] See also Fig.16 , for structures such as Fig. 9 The QLED device with an upright structure shown in the figure has a preparation method comprising the following steps:

[0204] providing an anode;

[0205] preparing a hole injection layer on the anode;

[0206] preparing a hole transport layer on the hole injection layer;

[0207] Preparing a quantum dot light-emitting layer on the hole transport layer;

[0208] preparing an electron transport layer on the quantum dot light-emitting layer;

[0209] Dissolving several different metal compounds and a first base in a first solvent to prepare a first base solution;

[0210] dissolving a second base in a second solvent to prepare a second base solution;

[0211] Adding the second alkaline solution to the first alkaline solution, refluxing the solution to prepare hollow microspheres containing perovskite composite metal oxides, and depositing the hollow microspheres containing perovskite composite metal oxides on the electron transport layer by a solution method to prepare a third interface modification layer;

[0212] hydrolyzing the third metal chloride at 120° C. to 250° C. under alkaline conditions to obtain a target metal oxide, and depositing the target metal oxide on the third interface modification layer by a solution method or a vapor deposition method to prepare a second interface modification layer;

[0213] The metal sulfide two-dimensional material and / or metal selenide two-dimensional material preparation method of the present invention is used to prepare the metal sulfide two-dimensional material or the metal selenide two-dimensional material respectively, and the target two-dimensional material is deposited on the second interface modification layer by a solution method or a vapor deposition method to prepare the first interface modification layer;

[0214] A cathode is prepared on the first interface modification layer.

[0215] In one embodiment, the Fig. 9 The hole transport layer, hole injection layer, quantum dot light-emitting layer and electron transport layer in the upright structure QLED device shown, the solution method is inkjet printing, dip coating or spin coating, the vapor deposition method is evaporation or magnetron sputtering, and the evaporation rate is 0.1nm / s~0.3nm / s; the anode is prepared by a vapor deposition method, such as evaporation, and the evaporation rate is 1nm / s~3nm / s.

[0216] In one embodiment, for a structure such as Fig. 9 The QLED device with an upright structure shown in the figure has a preparation method comprising the following steps:

[0217] providing an anode;

[0218] preparing a hole injection layer on the anode by inkjet printing;

[0219] preparing a hole transport layer on the hole injection layer by inkjet printing;

[0220] preparing a quantum dot light-emitting layer on the hole transport layer by inkjet printing;

[0221] preparing a quantum dot light-emitting layer on the hole transport layer by inkjet printing;

[0222] preparing an electron transport layer on the quantum dot light-emitting layer by inkjet printing;

[0223] Dissolving several different metal compounds and a first base in a first solvent to prepare a first base solution;

[0224] dissolving a second base in a second solvent to prepare a second base solution;

[0225] adding the second alkaline solution to the first alkaline solution, refluxing the solution to prepare hollow microspheres containing perovskite composite metal oxides, and depositing the hollow microspheres containing perovskite composite metal oxides on the electron transport layer by inkjet printing to prepare a third interface modification layer;

[0226] hydrolyzing the third metal chloride at 120° C. to 250° C. under alkaline conditions to obtain a target metal oxide, and depositing the target metal oxide on the third interface modification layer by inkjet printing to prepare a second interface modification layer;

[0227] The metal sulfide two-dimensional material and / or metal selenide two-dimensional material preparation method of the present invention is used to prepare the metal sulfide two-dimensional material or the metal selenide two-dimensional material respectively, and the above-mentioned target two-dimensional material is deposited on the second interface modification layer by inkjet printing to prepare the first interface modification layer;

[0228] A cathode is prepared on the first interface modification layer by magnetron sputtering.

[0229] The technical solution of the present invention is further described in detail below in conjunction with specific embodiments.

[0230] Unless otherwise specified, all raw materials in the present invention are from commercially available products. The solvent used for cleaning ITO is acetone.

[0231] Example 1

[0232] This embodiment provides an inverted QLED device and a preparation method thereof. The structure of the inverted QLED device is: cathode: ITO (15nm), Ag (140nm), ITO (15nm) / first interface modification layer: SnS2 (4nm) / second interface modification layer: SnO2 modification layer (2nm) / third interface modification layer: ZnSnO3 hollow microspheres (thickness 10nm) / electron transport layer: zinc oxide (50nm) / quantum dot light-emitting layer: CdSe / CdS (20nm) / hole transport layer: poly-TPD (30nm) / hole injection layer: PEDOT:PSS (20nm) / anode: Ag (20nm) / encapsulation layer (100nm).

[0233] The preparation method is as follows:

[0234] (1) A cathode electrode including a substrate is provided, wherein the cathode electrode includes ITO (15 nm), Ag (140 nm), and ITO (15 nm) stacked in sequence, and the cathode electrode is cleaned with a solvent.

[0235] (2) Two-dimensional SnS2 thin film was directly prepared on ITO by solvothermal method. The specific operation is as follows:

[0236] Weigh 6mmol of thioacetamide and 2mmol of SnCl4·5H2O respectively, add them into 40ml of anhydrous ethanol, and stir for 30min to prepare a mixed solution;

[0237] Transfer the mixed solution to a water heating tank, and place the cathode electrode into the water heating tank (ITO conductive surface facing downward), and place it in a drying oven at 180°C for 13 hours. Allow it to cool naturally to room temperature, so that a uniform SnS2 film with a thickness of about 6 nm is formed on the surface of the ITO. Wash it with anhydrous ethanol several times, and dry it for use.

[0238] (3) Preparation of SnO2, the specific operation is as follows:

[0239] The SnS2 film prepared on ITO was placed in a vacuum chamber for annealing. The vacuum chamber was filled with N2 protective gas to the standard pressure, and then annealed at 450°C for 2.5 hours. During the annealing process, 10 sccm of N2 was maintained at the air inlet, the air outlet was kept open, and 6 sccm of oxygen was maintained to prepare SnO2 with a thickness of about 2 nm. The thickness of the unoxidized SnS2 film was about 4 nm.

[0240] (4) Prepare a ZnSnO3 film layer, the outer diameter of the microsphere is 6nm and the inner diameter is 3nm. The specific operation is as follows:

[0241] 6mmolZn(NO3)2·6H2O, 6mmolSnCl4·5H2O and 60mmolNaOH were dissolved in 140ml water-ethanol solution (volume ratio of 5:5) to prepare a first alkaline solution; then 150mmolNaOH was dispersed in 40ml water-ethanol (volume ratio of 5:5) to prepare a second alkaline solution, and the second alkaline solution was slowly dripped into the first alkaline solution to form a suspension, stirred for 12min, and refluxed at 80°C for 2h, a white precipitate was collected, washed and dried, dissolved in ethanol to form an ink of 4mg / ml, and 8 drops were printed to form a ZnSnO3 film with a thickness of 10nm on the second interface modification layer.

[0242] (5) The zinc oxide electron transport layer was prepared on the ZnSnO3 film layer by inkjet printing method.

[0243] (6) The quantum dot light-emitting layer is prepared on the electron transport layer by inkjet printing.

[0244] (7) The hole transport layer is prepared on the quantum dot light-emitting layer by inkjet printing.

[0245] (8) The hole injection layer is prepared on the hole transport layer by inkjet printing.

[0246] (9) An anode is prepared on the hole injection layer by evaporation at a rate of 2 nm / s.

[0247] Example 2

[0248] This embodiment provides an inverted QLED device and a preparation method thereof. The structure of the inverted QLED device is: cathode: ITO (15nm), Ag (140nm), ITO (15nm) / first interface modification layer: SnS2 (5nm) / second interface modification layer: SnO2 modification layer (3nm) / third interface modification layer: ZnSnO3 hollow microspheres (thickness 10nm) / electron transport layer: zinc oxide (50nm) / quantum dot light-emitting layer: CdSe / CdS (20nm) / hole transport layer: poly-TPD (30nm) / hole injection layer: PEDOT:PSS (20nm) / anode: Ag (20nm) / encapsulation layer (100nm).

[0249] The preparation method is as follows:

[0250] (1) A cathode electrode including a substrate is provided, wherein the cathode electrode includes ITO (15 nm), Ag (140 nm), and ITO (15 nm) stacked in sequence, and the cathode electrode is cleaned with a solvent.

[0251] (2) Two-dimensional SnS2 thin film was directly prepared on ITO by solvothermal method. The specific operation is as follows:

[0252] Weigh 7mmol of thioacetamide and 5mmol of SnCl4·5H2O respectively, add them into 40ml of anhydrous ethanol, and stir for 30min to prepare a mixed solution;

[0253] Transfer the mixed solution to a water heating tank, and place the cathode electrode into the water heating tank (ITO conductive surface facing downward), and place it in a drying oven at 180°C for 15 hours. Allow it to cool naturally to room temperature, so that a uniform SnS2 film with a thickness of about 8nm is formed on the surface of the ITO. Wash it with anhydrous ethanol several times, and dry it for use.

[0254] (3) Preparation of SnO2, the specific operation is as follows:

[0255] The SnS2 film prepared on ITO was placed in a vacuum chamber for annealing. The vacuum chamber was filled with N2 protective gas to the standard pressure, and then annealed at 450°C for 3 hours. During the annealing process, 10 sccm of N2 was maintained at the air inlet, the air outlet was kept open, and 6 sccm of oxygen was maintained to prepare SnO2 with a thickness of about 3 nm. The thickness of the unoxidized SnS2 film was about 5 nm.

[0256] (4) Prepare a ZnSnO3 film layer, the outer diameter of the microsphere is 6nm and the inner diameter is 3nm. The specific operation is as follows:

[0257] 6mmolZn(NO3)2·6H2O, 6mmolSnCl4·5H2O and 60mmolNaOH were dissolved in 140ml water-ethanol solution (volume ratio of 5:5) to prepare a first alkaline solution; then 150mmolNaOH was dispersed in 40ml water-ethanol (volume ratio of 5:5) to prepare a second alkaline solution, and the second alkaline solution was slowly dripped into the first alkaline solution to form a suspension, stirred for 12min, and refluxed at 80°C for 2h, a white precipitate was collected, washed and dried, dissolved in ethanol to form an ink of 4mg / ml, and 8 drops were printed to form a ZnSnO3 film with a thickness of 10nm on the second interface modification layer.

[0258] (5) A zinc oxide electron transport layer is prepared on the ZnSnO3 film layer by an evaporation method with an evaporation rate of 0.2 nm / s.

[0259] (6) The quantum dot light-emitting layer is prepared on the electron transport layer by inkjet printing.

[0260] (7) The hole transport layer is prepared on the quantum dot light-emitting layer by inkjet printing.

[0261] (8) The hole injection layer is prepared on the hole transport layer by inkjet printing.

[0262] (9) An anode is prepared on the hole injection layer by evaporation at a rate of 2 nm / s.

[0263] Example 3

[0264] This embodiment provides an inverted QLED device and a preparation method thereof. The structure of the inverted QLED device is: cathode: ITO (15nm), Ag (140nm), ITO (15nm) / first interface modification layer: InS (5nm) / second interface modification layer: InO modification layer (5nm) / third interface modification layer: ZnSnO3 hollow microspheres (thickness 15nm) / electron transport layer: zinc oxide (50nm) / quantum dot light-emitting layer: CdSe / CdS (20nm) / hole transport layer: poly-TPD (30nm) / hole injection layer: PEDOT:PSS (20nm) / anode: Ag (20nm) / encapsulation layer (100nm).

[0265] The preparation method is as follows:

[0266] (1) A cathode electrode including a substrate is provided, wherein the cathode electrode includes ITO (15 nm), Ag (140 nm), and ITO (15 nm) stacked in sequence, and the cathode electrode is cleaned with a solvent.

[0267] (2) Two-dimensional InS thin film was directly prepared on ITO by solvothermal method. The specific operation is as follows:

[0268] Weigh 6mmol of thioacetamide and 2mmol of InCl2·5H2O respectively, add them into 50ml of anhydrous ethanol, stir for 20min, and prepare a mixed solution;

[0269] Transfer the mixed solution to a hydrothermal tank, and place the cathode electrode into the hydrothermal tank (ITO conductive surface facing downward), and place it in a drying oven at 180°C for 20 hours. Allow it to cool naturally to room temperature, so that a uniform InS film is formed on the surface of the ITO with a thickness of about 10 nm. Wash it with anhydrous ethanol several times, and dry it for use.

[0270] (3) Preparation of InO, the specific operation is as follows:

[0271] The InS film prepared on ITO was placed in a vacuum chamber for annealing. The vacuum chamber was filled with N2 protective gas to the standard pressure, and then annealed at 400°C for 4 hours. During the annealing process, 10 sccm of N2 was maintained at the air inlet, the air outlet was kept open, and 8 sccm of oxygen was maintained to flow in. InO with a thickness of about 5 nm was prepared, and the thickness of the unoxidized InS film was about 5 nm.

[0272] (4) Prepare a ZnSnO3 film layer, the outer diameter of the microsphere is 8nm and the inner diameter is 3nm. The specific operation is as follows:

[0273] 6mmolZn(NO3)2·6H2O, 6mmolSnCl4·5H2O and 60mmolNaOH were dissolved in 140ml water-ethanol solution (volume ratio of 5:5) to prepare a first alkaline solution; then 150mmolNaOH was dispersed in 40ml water-ethanol (volume ratio of 5:5) to prepare a second alkaline solution, and the second alkaline solution was slowly dripped into the first alkaline solution to form a suspension, stirred for 20min, and refluxed at 80°C for 2h, a white precipitate was collected, washed and dried, dissolved in ethanol to form an ink of 4mg / ml, and 12 drops were printed to form a ZnSnO3 film with a thickness of 15nm on the second interface modification layer.

[0274] (5) The zinc oxide electron transport layer was prepared on the ZnSnO3 film layer by inkjet printing method.

[0275] (6) The quantum dot light-emitting layer is prepared on the electron transport layer by inkjet printing.

[0276] (7) A hole transport layer is prepared on the quantum dot light-emitting layer by evaporation at a rate of 0.2 nm / s.

[0277] (8) The hole injection layer is prepared on the hole transport layer by inkjet printing.

[0278] (9) An anode is prepared on the hole injection layer by evaporation at a rate of 2 nm / s.

[0279] Example 4

[0280] This embodiment provides an inverted QLED device and a preparation method thereof. The structure of the inverted QLED device is: cathode: ITO (15nm), Ag (140nm), ITO (15nm) / interface modification layer: SnS2 (6nm) / electron transport layer: zinc oxide (50nm) / quantum dot light-emitting layer: CdSe / CdS (20nm) / hole transport layer: poly-TPD (30nm) / hole injection layer: PEDOT: PSS (20nm) / anode: Ag (20nm) / encapsulation layer (100nm).

[0281] The preparation method is as follows:

[0282] (1) A cathode electrode including a substrate is provided, wherein the cathode electrode includes ITO (15 nm) + Ag (140 nm) + ITO (15 nm) stacked in sequence, and the cathode electrode is cleaned with a solvent.

[0283] (2) Two-dimensional SnS2 thin film was prepared on ITO by solvothermal method. The specific operation is as follows:

[0284] Weigh 6mmol of thioacetamide and 2mmol of SnCl4·5H2O respectively, add them into 40ml of anhydrous ethanol, and stir for 30min to prepare a mixed solution;

[0285] Transfer the mixed solution to a water heating tank, and place the cathode electrode into the water heating tank (ITO conductive surface facing downward), and place it in a drying oven at 180°C for 13 hours. Allow it to cool naturally to room temperature, so that a uniform SnS2 film with a thickness of about 6 nm is formed on the surface of the ITO. Wash it with anhydrous ethanol several times, and dry it for use.

[0286] (3) The zinc oxide electron transport layer was prepared on the SnS2 film layer by inkjet printing method.

[0287] (4) The quantum dot light-emitting layer is prepared on the electron transport layer by inkjet printing.

[0288] (5) A hole transport layer is prepared on the quantum dot light-emitting layer by inkjet printing.

[0289] (6) The hole injection layer is prepared on the hole transport layer by inkjet printing.

[0290] (7) An anode is prepared on the hole injection layer by evaporation at a rate of 2 nm / s.

[0291] Example 5

[0292] This embodiment provides an inverted QLED device and a preparation method thereof. The structure of the inverted QLED device is: cathode: ITO (15nm), Ag (140nm), ITO (15nm) / first interface modification layer: SnS2 (4nm) / second interface modification layer: SnO2 modification layer (2nm) / electron transport layer: zinc oxide (50nm) / quantum dot light-emitting layer: CdSe / CdS (20nm) / hole transport layer: poly-TPD (30nm) / hole injection layer: PEDOT: PSS (20nm) / anode: Ag (20nm) / encapsulation layer (100nm).

[0293] The preparation method is as follows:

[0294] (1) A cathode electrode including a substrate is provided, wherein the cathode electrode includes ITO (15 nm), Ag (140 nm), and ITO (15 nm) stacked in sequence, and the cathode electrode is cleaned with a solvent.

[0295] (2) Two-dimensional SnS2 thin film was directly prepared on ITO by solvothermal method. The specific operation is as follows:

[0296] Weigh 6 mmol of thioacetamide and 2 mmol of SnCl4·5H2O respectively, add them into 40 ml of anhydrous ethanol, and stir for 30 minutes to prepare a first mixed solution;

[0297] Transfer the first mixed solution to a hydrothermal tank, and place the cathode electrode into the hydrothermal tank (ITO conductive surface facing downward), and place it in a drying oven at 180°C for 13 hours. Allow it to cool naturally to room temperature, so that a uniform SnS2 film with a thickness of about 6 nm is formed on the surface of the ITO. Wash it with anhydrous ethanol several times, and dry it for use.

[0298] (3) Preparation of SnO2, the specific operation is as follows:

[0299] The SnS2 film prepared on ITO was placed in a vacuum chamber for annealing. The vacuum chamber was filled with N2 protective gas to the standard pressure, and then annealed at 450°C for 2.5 hours. During the annealing process, 10 sccm of N2 was maintained at the air inlet, the air outlet was kept open, and 6 sccm of oxygen was maintained to prepare SnO2 with a thickness of about 2 nm. The thickness of the unoxidized SnS2 film was about 4 nm.

[0300] (4) The zinc oxide electron transport layer was prepared on the SnO2 film layer by inkjet printing method.

[0301] (5) The quantum dot light-emitting layer is prepared on the electron transport layer by inkjet printing.

[0302] (6) A hole transport layer is prepared on the quantum dot light-emitting layer by inkjet printing.

[0303] (7) The hole injection layer is prepared on the hole transport layer by inkjet printing.

[0304] (8) An anode is prepared on the hole injection layer by evaporation at a rate of 0.2 nm / s.

[0305] Example 6

[0306] This embodiment provides an inverted QLED device and a preparation method thereof. The structure of the inverted QLED device is: cathode: ITO (15nm), Ag (140nm), ITO (15nm) / first interface modification layer: SnS2 (6nm) / second interface modification layer: ZnSnO3 hollow microspheres (thickness 15nm) / electron transport layer: zinc oxide (50nm) / quantum dot light-emitting layer: CdSe / CdS (20nm) / hole transport layer: poly-TPD (30nm) / hole injection layer: PEDOT: PSS (20nm) / anode: Ag (20nm) / encapsulation layer (100nm).

[0307] The preparation method is as follows:

[0308] (1) A cathode electrode including a substrate is provided, wherein the cathode electrode includes ITO (15 nm) + Ag (140 nm) + ITO (15 nm) stacked in sequence, and the cathode electrode is cleaned with a solvent.

[0309] (2) A two-dimensional SnS2 thin film was directly prepared on an ITO electrode using a solvothermal method. The specific operation is as follows:

[0310] Weigh 6mmol of thioacetamide and 2mmol of SnCl4·5H2O respectively, add them into 40ml of anhydrous ethanol, and stir for 30min to prepare a mixed solution;

[0311] Transfer the mixed solution to a water heating tank, and place the cathode electrode into the water heating tank (ITO conductive surface facing downward), and place it in a drying oven at 180°C for 13 hours. Allow it to cool naturally to room temperature, so that a uniform SnS2 film with a thickness of about 6 nm is formed on the surface of the ITO. Wash it with anhydrous ethanol several times, and dry it for use.

[0312] (3) Prepare a ZnSnO3 film layer, the outer diameter of the microsphere is 8nm and the inner diameter is 3nm. The specific operation is as follows:

[0313] 6mmolZn(NO3)2·6H2O, 6mmolSnCl4·5H2O and 60mmolNaOH were dissolved in 140ml water-ethanol solution (volume ratio of 5:5) to prepare a first alkaline solution; then 150mmolNaOH was dispersed in 40ml water-ethanol (volume ratio of 5:5) to prepare a second alkaline solution, and the second alkaline solution was slowly dripped into the first alkaline solution to form a suspension, stirred for 20min, and refluxed at 80°C for 2h, a white precipitate was collected, washed and dried, dissolved in ethanol to form an ink of 4mg / ml, and 12 drops were printed to form a ZnSnO3 film with a thickness of 15nm on the first interface modification layer.

[0314] (5) The zinc oxide electron transport layer was prepared on the ZnSnO3 film layer by inkjet printing method.

[0315] (6) The quantum dot light-emitting layer is prepared on the electron transport layer by inkjet printing.

[0316] (7) The hole transport layer is prepared on the quantum dot light-emitting layer by inkjet printing.

[0317] (8) The hole injection layer is prepared on the hole transport layer by inkjet printing.

[0318] (9) An anode is prepared on the hole injection layer by evaporation at a rate of 2 nm / s.

[0319] Example 7

[0320] This embodiment provides an inverted QLED device and a preparation method thereof. The structure of the inverted QLED device is: cathode: IZO (15nm), Ag (140nm), IZO (15nm) / first interface modification layer: InS (5nm) / second interface modification layer: InO modification layer (5nm) / third interface modification layer: BaTiO3 hollow microspheres (thickness 15nm) / electron transport layer: titanium oxide (50nm) / quantum dot light-emitting layer: CdSe / CdS (20nm) / hole transport layer: poly-TPD (30nm) / hole injection layer: PEDOT:PSS (20nm) / anode: Ag (20nm) / encapsulation layer (100nm).

[0321] The preparation method is as follows:

[0322] (1) A cathode electrode including a substrate is provided. The cathode electrode includes IZO (15 nm), Ag (140 nm), and IZO (15 nm) stacked in sequence. The cathode electrode is cleaned with a solvent.

[0323] (2) Two-dimensional InS thin film was directly prepared on IZO by solvothermal method. The specific operation is as follows:

[0324] Weigh 6mmol of thioacetamide and 2mmol of InCl2·5H2O respectively, add them into 50ml of anhydrous ethanol, stir for 20min, and prepare a mixed solution;

[0325] Transfer the mixed solution to a hydrothermal tank, and place the cathode electrode into the hydrothermal tank (with the IZO conductive surface facing downward), and place it in a drying oven at 180°C for 20 hours. Allow it to cool naturally to room temperature, so that a uniform InS film is formed on the surface of the IZO with a thickness of about 10 nm. Wash it with anhydrous ethanol several times, and dry it for later use.

[0326] (3) Preparation of InO, the specific operation is as follows:

[0327] The InS film prepared on IZO was placed in a vacuum chamber for annealing. The vacuum chamber was filled with N2 protective gas to the standard pressure, and then annealed at 400°C for 4 hours. During the annealing process, 10 sccm of N2 was maintained at the gas inlet, the outlet was kept open, and 8 sccm of oxygen was maintained to prepare InO with a thickness of about 5 nm. The thickness of the unoxidized InS film was about 5 nm.

[0328] (4) Prepare a BaTiO3 film layer, the outer diameter of the microsphere is 8nm and the inner diameter is 3nm. The specific operation is as follows:

[0329] 6mmolBa(C2O4)2·4H2O, 6mmolTiCl4·5H2O and 60mmolNaOH were dissolved in 140ml water-ethanol solution (volume ratio of 5:5) to prepare a first alkaline solution; then 150mmolNaOH was dispersed in 40ml water-ethanol (volume ratio of 5:5) to prepare a second alkaline solution, and the second alkaline solution was slowly dripped into the first alkaline solution to form a suspension, stirred for 20min, and refluxed at 90°C for 1h, a white precipitate was collected, washed and dried, dissolved in ethanol to form an ink of 4mg / ml, and 12 drops were printed to form a BaTiO3 film with a thickness of 15nm on the second interface modification layer.

[0330] (5) The titanium oxide electron transport layer was prepared on the BaTiO3 film layer by inkjet printing method.

[0331] (6) The quantum dot light-emitting layer is prepared on the electron transport layer by inkjet printing.

[0332] (7) A hole transport layer is prepared on the quantum dot light-emitting layer by evaporation at a rate of 0.2 nm / s.

[0333] (8) The hole injection layer is prepared on the hole transport layer by inkjet printing.

[0334] (9) An anode is prepared on the hole injection layer by evaporation at a rate of 2 nm / s.

[0335] Example 8

[0336] This embodiment provides a positive QLED device and a preparation method thereof. The structure of the positive QLED device is: anode: ITO (15nm), Ag (140nm), ITO (15nm) / hole injection layer: PEDOT: PSS (20nm) / hole transport layer: poly-TPD (30nm) / quantum dot light-emitting layer: CdSe / CdS (20nm) / electron transport layer: zinc oxide (50nm) / third interface modification layer: ZnSnO3 hollow microspheres (thickness 15nm) / second interface modification layer SnO2 modification layer (2nm) / first interface modification layer: SnS2 (6nm) / cathode is ITO (20nm)) / encapsulation layer (100nm).

[0337] The preparation method is as follows:

[0338] (1) An anode electrode including a substrate is provided. The anode electrode includes ITO (15 nm), Ag (140 nm), and ITO (15 nm) stacked in sequence. The anode electrode is cleaned with a solvent.

[0339] (2) The hole injection layer was prepared on ITO by inkjet printing method.

[0340] (3) The hole transport layer is prepared on the hole injection by inkjet printing method.

[0341] (4) The quantum dot light-emitting layer was prepared on the hole transport layer using inkjet printing method.

[0342] (5) The zinc oxide electron transport layer is prepared on the quantum dot light-emitting layer by inkjet printing method.

[0343] (6) Prepare the corresponding modified layer, the specific operation is as follows:

[0344] 6.1) Prepare ZnSnO3 film layer, the outer diameter of microspheres is 8nm, and the inner diameter is 3nm. The specific operation is as follows:

[0345] 6mmolZn(NO3)2·6H2O, 6mmolSnCl4·5H2O and 60mmolNaOH were dissolved in 140ml water-ethanol solution (volume ratio of 5:5) to prepare a first alkaline solution; then 150mmolNaOH was dispersed in 40ml water-ethanol (volume ratio of 5:5) to prepare a second alkaline solution, and the second alkaline solution was slowly dripped into the first alkaline solution to form a suspension, stirred for 20min, and refluxed at 80°C for 2h, a white precipitate was collected, washed and dried, dissolved in ethanol to form an ink of 4mg / ml, and 12 drops were printed to form a ZnSnO3 film with a thickness of 15nm on the zinc oxide electron transport layer.

[0346] 6.2) Preparation of SnO2 thin film:

[0347] First, SnO2 particles were prepared. 0.01 mol SnCl2·5H2O was dissolved in 50 ml methanol and ultrasonically shaken for 30 min to fully dissolve. Then, hexadecyltrimethylammonium bromide was added to adjust the pH to 9. The mixture was reacted at 180°C for 12 h to obtain powder. The powder was taken out and washed to prepare 2 mg / ml SnO2-ethanol printing ink. Four drops were printed to form a SnO2 thin film modification layer with a thickness of 2 nm on the ZnSnO3 film layer.

[0348] 6.3) Preparation of SnS2 (6nm) thin film

[0349] 6 mmol of thioacetamide and 2 mmol of SnCl4·5H2O were weighed separately and added into 40 ml of anhydrous ethanol, and stirred for 30 min to prepare a mixed solution; the mixed solution was kept at 180°C in a drying oven for 13 h, cooled naturally to room temperature, and dried to obtain SnS2 powder, which was then configured into 2 mg / ml SnS2-ethanol ink, and 6 drops were inkjet printed to form a 6 nm thick SnS2 film.

[0350] (7) The cathode was prepared by magnetron sputtering, wherein: the sputtering power was 80 W, the sputtering pressure was 1 Pa, the sputtering rate was 1 nm / s, and the sputtering time was 20 min. A 20 nm ITO film was obtained on the SnS2 film, which was used as the cathode.

[0351] Comparative Example 1

[0352] This comparative example provides an inverted QLED device and a preparation method thereof. The structure of the inverted QLED device is: cathode: ITO (15nm), Ag (140nm), ITO (15nm) / electron transport layer: zinc oxide (50nm) / quantum dot light-emitting layer: CdSe / CdS (20nm) / hole transport layer: poly-TPD (30nm) / hole injection layer: PEDOT:PSS (20nm) / anode: Ag (20nm) / encapsulation layer (100nm).

[0353] The preparation method is as follows:

[0354] (1) A cathode electrode including a substrate is provided, wherein the cathode electrode includes ITO (15 nm) + Ag (140 nm) + ITO (15 nm) stacked in sequence, and the cathode electrode is cleaned with a solvent.

[0355] (2) The zinc oxide electron transport layer was prepared on ITO by inkjet printing method.

[0356] (3) The quantum dot light-emitting layer is prepared on the electron transport layer by inkjet printing.

[0357] (4) The hole transport layer is prepared on the quantum dot light-emitting layer by inkjet printing.

[0358] (5) The hole injection layer is prepared on the hole transport layer by inkjet printing.

[0359] (6) An anode is prepared on the hole injection layer by evaporation at a rate of 2 nm / s.

[0360] Comparative Example 2

[0361] This comparative example provides an inverted QLED device and a preparation method thereof. The structure of the inverted QLED device is: cathode: IZO (15nm), Ag (140nm), IZO (15nm) / electron transport layer: titanium oxide (50nm) / quantum dot light-emitting layer: CdSe / CdS (20nm) / hole transport layer: poly-TPD (30nm) / hole injection layer: PEDOT:PSS (20nm) / anode: Ag (20nm) / encapsulation layer (100nm).

[0362] The preparation method is as follows:

[0363] (1) A cathode electrode including a substrate is provided. The cathode electrode includes IZO (15 nm), Ag (140 nm), and IZO (15 nm) stacked in sequence. The cathode electrode is cleaned with a solvent.

[0364] (2) The titanium oxide electron transport layer was prepared on IZO by inkjet printing method.

[0365] (3) The quantum dot light-emitting layer is prepared on the electron transport layer by inkjet printing.

[0366] (4) The hole transport layer is prepared on the quantum dot light-emitting layer by inkjet printing.

[0367] (5) The hole injection layer is prepared on the hole transport layer by inkjet printing.

[0368] (6) An anode is prepared on the hole injection layer by evaporation at a rate of 2 nm / s.

[0369] Comparative Example 3

[0370] This comparative example provides a positive QLED device and a preparation method thereof. The structure of the positive QLED device is: anode: ITO (15nm), Ag (140nm), ITO (15nm) / hole injection layer PEDOT: PSS (20nm) / hole transport layer: poly-TPD (30nm) / quantum dot light-emitting layer: CdSe / CdS (20nm) / electron transport layer: zinc oxide (50nm) / cathode: ITO (20nm) / encapsulation layer (100nm).

[0371] The preparation method is as follows:

[0372] (1) An anode electrode including a substrate is provided. The anode electrode includes ITO (15 nm), Ag (140 nm), and ITO (15 nm) stacked in sequence. The anode electrode is cleaned with a solvent.

[0373] (2) The hole injection layer was prepared on the anode using an inkjet printing method.

[0374] (3) The hole transport layer is prepared on the hole injection by inkjet printing method.

[0375] (4) The quantum dot light-emitting layer was prepared on the hole transport layer using inkjet printing method.

[0376] (5) The zinc oxide electron transport layer is prepared on the quantum dot light-emitting layer by inkjet printing method.

[0377] (6) The cathode was prepared by magnetron sputtering, wherein: the sputtering power was 80 W, the sputtering pressure was 1 Pa, the sputtering rate was 1 nm / s, and the sputtering time was 20 min. A 20 nm thick ITO film was obtained on the electron transport layer as the cathode.

[0378] test

[0379] The inverted QLED device embodiments 1 to 7 and the inverted QLED device comparative examples 1 to 2 were subjected to performance tests, and the results are shown in Table 1. The upright QLED device embodiment 8 and comparative example 3 were subjected to performance tests, and the results are shown in Table 2. RQD refers to a red quantum dot device, and EQE refers to external quantum efficiency, which is generally used to characterize the efficiency of a device:

[0380] Table 1

[0381] Test subjects Cathode work function (eV) EQE(RQD) Device Example 1 4.2 7.7％ Device Example 2 4.2 6.4％ Device Example 3 4.18 8.5％ Device Example 4 4.2 6％ Device Example 5 4.2 6.2％ Device Example 6 4.2 6.6％ Device Example 7 4.5 5.4％ Device Comparison Example 1 4.6 5.3％ Device Comparison Example 2 5 4.8％

[0382] Table 2

[0383] Test subjects Cathode work function (eV) EQE(RQD) Device Example 8 4.4 5.5％ Device Comparison Example 3 4.6 5.3％

[0384] It can be seen from Tables 1 and 2 that the device efficiency of the device with modified ITO or IZO in the cathode is significantly improved. This is mainly because the cathode electrode is modified, which makes it easier for electrons to be injected and carriers to align in the light-emitting area, thereby increasing the device's luminous efficiency.

[0385] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0386] The above-described embodiments only express several implementation methods of the present invention, which are convenient for understanding the technical solutions of the present invention in detail, but they cannot be understood as limiting the scope of protection of the invention patent. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, several modifications and improvements can be made, which all belong to the protection scope of the present invention. It should be understood that the technical solutions obtained by ordinary technicians in this field through logical analysis, reasoning or limited experiments on the basis of the technical solutions provided by the present invention are all within the protection scope of the claims attached to the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the contents of the attached claims, and the description and drawings can be used to explain the contents of the claims.

Claims

1. A quantum dot light emitting diode, characterized in that: The invention comprises an anode, a cathode, a quantum dot light-emitting layer disposed between the anode and the cathode, an electron transport layer disposed between the quantum dot light-emitting layer and the cathode, and an interface modification layer disposed between the cathode and the electron transport layer and in contact with the cathode; The interface modification layer comprises a first interface modification layer and a second interface modification layer which are stacked, wherein the first interface modification layer is close to the cathode and the second interface modification layer is close to the electron transport layer; The first interface modification layer comprises a metal sulfide two-dimensional material and / or a metal selenide two-dimensional material; The second interface modification layer comprises perovskite composite metal oxide hollow microspheres; Or, the interface modification layer comprises a first interface modification layer, a second interface modification layer and a third interface modification layer which are stacked, the first interface modification layer is close to the cathode, and the third interface modification layer is close to the electron transport layer; The first interface modification layer comprises a metal sulfide two-dimensional material and / or a metal selenide two-dimensional material; The second interface modification layer comprises a metal oxide, and the metal element in the metal oxide is the same as the metal element in the metal sulfide or metal selenide; The third interface modification layer comprises perovskite composite metal oxide hollow microspheres.

2. The quantum dot light emitting diode according to claim 1, characterized in that: The metal sulfide is tin disulfide or tungsten disulfide, and the metal selenide is tin diselenide or indium selenide; The metal oxide is tin oxide, tungsten trioxide, tungsten pentoxide or indium oxide; The perovskite composite metal oxide is zinc metastannate, zinc titanate, barium titanate or zinc cobaltate.

3. The quantum dot light emitting diode according to claim 2, characterized in that: The thickness ratio of the first interface modification layer to the second interface modification layer containing the metal oxide is (0.5-5):

1.

4. The quantum dot light emitting diode according to claim 2, characterized in that: The thickness of the first interface modification layer is 4 nm to 10 nm, and the thickness of the second interface modification layer containing the metal oxide is 2 nm to 6 nm.

5. The quantum dot light emitting diode according to claim 2, characterized in that: The thickness of the second interface modification layer containing the perovskite composite metal oxide hollow microspheres is 10 nm to 15 nm; or The thickness of the third interface modification layer is 10 nm to 15 nm.

6. A method for preparing a quantum dot light-emitting diode according to any one of claims 1 to 5, characterized in that: The method comprises the steps of preparing an interface modification layer containing hollow microspheres of perovskite composite metal oxides between a cathode and an electron transport layer, wherein the preparation of the interface modification layer containing hollow microspheres of perovskite composite metal oxides comprises the following steps: Perovskite composite metal oxide hollow microspheres are provided to prepare the interface modification layer containing the perovskite composite metal oxide hollow microspheres.

7. The method for preparing a quantum dot light-emitting diode according to claim 6, characterized in that: The interface modification layer comprises a first interface modification layer and a second interface modification layer which are stacked, wherein the first interface modification layer is close to the cathode and the second interface modification layer is close to the electron transport layer; The first interface modification layer comprises the metal sulfide two-dimensional material and / or the metal selenide two-dimensional material; The second interface modification layer comprises perovskite composite metal oxide hollow microspheres.

8. The method for preparing a quantum dot light-emitting diode according to claim 6, characterized in that: The interface modification layer comprises a first interface modification layer, a second interface modification layer and a third interface modification layer which are stacked, wherein the first interface modification layer is close to the cathode, and the third interface modification layer is close to the electron transport layer; The first interface modification layer comprises the metal sulfide two-dimensional material and / or the metal selenide two-dimensional material; The second interface modification layer comprises a metal oxide, and the metal element in the metal oxide is the same as the metal element in the metal sulfide or metal selenide; The third interface modification layer comprises perovskite composite metal oxide hollow microspheres.

9. The method for preparing a quantum dot light-emitting diode according to claim 7 or 8, characterized in that: The preparation method of the metal oxide comprises the following steps: Annealing and oxidation treatment of the two-dimensional material at 400°C to 500°C in an oxygen-containing, protective gas atmosphere; The two-dimensional material is a metal sulfide two-dimensional material and / or a metal selenide two-dimensional material.

10. The method for preparing a quantum dot light-emitting diode according to claim 9, characterized in that: The flow rate of oxygen is 5 sccm to 10 sccm, the oxidation time is 2h to 3h, and the thickness ratio of the unoxidized two-dimensional material to the oxidized two-dimensional material is (1.5 to 5):

1.

11. The method for preparing a quantum dot light-emitting diode according to claim 7 or 8, characterized in that: The preparation method of the metal oxide comprises the following steps: The third metal chloride is hydrolyzed at 120° C. to 250° C. under alkaline conditions.

12. The method for preparing a quantum dot light-emitting diode according to claim 11, characterized in that: The hydrolysis treatment time is 10h to 20h, and the pH value of the reaction system is 8 to 11.

13. The method for preparing a quantum dot light-emitting diode according to claim 7 or 8, characterized in that: The preparation method of the perovskite composite metal oxide hollow microspheres comprises the following steps: Dissolving several different metal compounds and a first base in a first solvent to prepare a first base solution; dissolving a second base in a second solvent to prepare a second base solution; The second alkaline solution is added to the first alkaline solution for reflux reaction.

14. The method for preparing a quantum dot light-emitting diode according to claim 13, characterized in that: The metal compound is at least two of tin disulfide, indium disulfide and dock disulfide.

15. The method for preparing a quantum dot light-emitting diode according to claim 13, characterized in that: The first alkali includes sodium hydroxide, and the first alkali also includes at least one of zinc nitrate, tin chloride and indium chloride; The second alkali is selected from at least one of sodium hydroxide, sodium methoxide and potassium hydroxide.

16. The method for preparing a quantum dot light-emitting diode according to claim 13, characterized in that: The first solvent and the second solvent are both mixed solvents of alcohol and water.

17. The method for preparing a quantum dot light-emitting diode according to claim 7 or 8, characterized in that: The metal sulfide is tin disulfide or tungsten disulfide, and the metal selenide is tin diselenide or indium selenide; The metal oxide is tin oxide, tungsten trioxide, tungsten pentoxide or indium oxide; The perovskite composite metal oxide is zinc metastannate, zinc titanate, barium titanate or zinc cobaltate.

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