Perovskite quantum dot miniature light-emitting diode device and preparation method thereof

Abstract

The invention relates to the technical field of semiconductor photoelectrons, and provides a perovskite quantum dot micro light-emitting diode device and a preparation method thereof. The perovskite quantum dot micro light-emitting diode device comprises a first electrode layer, an interface regulation and control layer, a perovskite array layer, an electron transport layer and a second electrode layer which are stacked in sequence, the interface regulation and control layer is one of a first interface regulation and control layer, a second interface regulation and control layer and a third interface regulation and control layer; the perovskite array layer comprises a red perovskite quantum dot layer, a green perovskite quantum dot layer and a blue perovskite quantum dot layer which are arranged in parallel. According to the invention, large-area full-color display can be realized under the condition that a chip mass transfer technology is not used, and the problem that full-color display is difficult to realize due to the fact that chip mass transfer is difficult in the prior art is solved.

Description

Technical Field

[0001] The present application relates to the field of semiconductor optoelectronic technology, and in particular to a perovskite quantum dot micro light emitting diode device and a preparation method thereof. Background Art

[0002] Self-luminous diodes with pixels smaller than 50 microns are called micro-light-emitting diodes (Micro-LEDs). Compared with liquid crystal displays (LCDs) and organic light-emitting diodes (OLEDs), micro-LEDs have advantages such as high contrast, fast response, wide color gamut, and low power consumption. They have broad application prospects in display fields such as virtual reality (VR), augmented reality (AR), wearable devices, smart phones, and high-definition televisions (HDTVs).

[0003] At present, the technology of micro-LED is not mature yet, so it is difficult to realize the large-scale commercial application of micro-LED. Among them, full-color technology is one of the technical difficulties of micro-LED.

[0004] Existing micro-LEDs are usually III-V semiconductor micro-LEDs, whose red light-emitting chips are usually made of indium gallium phosphide (InGaP), and blue and green light-emitting chips are usually made of indium gallium nitride (InGaN) semiconductors. Full color is usually achieved through mass transfer of chips. For displays with higher resolution requirements (such as 8K displays), the number of chips to be transferred is very large (tens of millions or even more than 100 million), and the difficulty of chip transfer is very large, so it is difficult to achieve large-area full-color display, and the cost is also extremely high. In addition, the current full-color technology mainly focuses on the color conversion film of the blue backlight micro-LED, and this color conversion full-color solution still faces the problems of difficulty in mass transfer of chips and cumbersome processes.

[0005] It can be seen that traditional micro-light-emitting diodes still have problems such as difficulty in transferring large quantities of chips, complicated processes, difficulty in achieving large-area full-color display, large limitations in application scenarios, and high costs. Summary of the invention

[0006] In view of this, the purpose of the present application is to provide a perovskite quantum dot micro light emitting diode device and a preparation method thereof, so as to solve the problems in the prior art that micro light emitting diodes still have difficulties in mass chip transfer, complicated processes, difficulty in achieving large-area full-color display, large limitations in application scenarios, and high costs.

[0007] In order to achieve the above-mentioned invention object, the present application provides the following technical solutions:

[0008] In a first aspect, the present application provides a perovskite quantum dot micro light emitting diode device, which is prepared according to the preparation method of the perovskite quantum dot micro light emitting diode device of the first aspect;

[0009] The perovskite quantum dot micro-light-emitting diode device comprises a first electrode layer, an interface control layer, a perovskite array layer, an electron transport layer and a second electrode layer which are stacked in sequence;

[0010] Among them, the interface regulation layer is one of the first interface regulation layer, the second interface regulation layer or the third interface regulation layer; the perovskite array layer includes a red perovskite quantum dot layer, a green perovskite quantum dot layer and a blue perovskite quantum dot layer arranged in parallel.

[0011] In a second aspect, the present application provides a method for preparing a perovskite quantum dot micro light emitting diode device, comprising the following steps:

[0012] Prepare a first solution, a second solution, a surface modification solution and a perovskite quantum dot ink respectively and set them aside;

[0013] sequentially coating a first solution and a surface modification solution on the surface of the first electrode layer to form a first interface regulation layer on the first electrode layer, or sequentially coating a second solution and a surface modification solution on the surface of the first electrode layer to form a second interface regulation layer on the first electrode layer; or sequentially coating a first solution, a second solution, and a surface modification solution on the surface of the first electrode layer to form a third interface regulation layer on the first electrode layer;

[0014] The perovskite quantum dot ink is inkjet printed onto the first interface regulation layer to form a perovskite array layer on the first interface regulation layer; or the perovskite quantum dot ink is inkjet printed onto the second interface regulation layer to form a perovskite array layer on the second interface regulation layer; or the perovskite quantum dot ink is inkjet printed onto the third interface regulation layer to form a perovskite array layer on the third interface regulation layer; wherein the perovskite array layer includes a red perovskite quantum dot layer, a green perovskite quantum dot layer and a blue perovskite quantum dot layer arranged in parallel;

[0015] Evaporating an electron transport material onto the surface of the perovskite array layer to form an electron transport layer on the perovskite array layer;

[0016] The electrode material is evaporated onto the surface of the electron transport layer to form a second electrode layer on the electron transport layer, thereby obtaining a perovskite quantum dot micro light emitting diode device.

[0017] The perovskite quantum dot micro light emitting diode device and its preparation method provided in this application have the following characteristics:

[0018] Beneficial effects:

[0019] The preparation method of the perovskite quantum dot micro light-emitting diode device provided in the embodiment of the present application is to first apply the first solution and the surface modification solution, or the second solution and the surface modification solution, or the first solution, the second solution and the surface modification solution on the surface of the first electrode layer to form a first interface regulation layer or a second interface regulation layer or a third interface regulation layer, and then inkjet print the perovskite quantum dot ink onto the first interface regulation layer or the second interface regulation layer or the third interface regulation layer. In this way, the perovskite quantum dot ink can be accurately deposited onto the first interface regulation layer or the second interface regulation layer or the third interface regulation layer to form a micro-sized emission pixel array (i.e., the perovskite array layer) with uniform brightness, and large-area full-color display can be achieved without using chip mass transfer technology, thereby overcoming the problem in the prior art that it is difficult to achieve full-color display due to the difficulty of chip mass transfer, and breaking the limitations of the application scenarios of traditional micro light-emitting diodes. At the same time, the preparation method provided in the present application has a simple process, and the light-emitting layer is a perovskite array layer. The materials used to prepare the perovskite array layer are widely available and inexpensive, which can greatly reduce the material and preparation costs and is conducive to the large-scale commercial application of micro light-emitting diodes.

[0020] The perovskite quantum dot micro-light-emitting diode device prepared by the perovskite quantum dot micro-light-emitting diode device preparation method provided in the embodiment of the present application has a pixel size that can be reduced to less than 30 microns, has excellent luminescence performance, and can achieve large-area full-color display without using chip mass transfer technology, and has a wide range of application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 It is a schematic structural diagram of the first perovskite quantum dot micro light-emitting diode device provided in an embodiment of the present application;

[0023] Figure 2 It is a schematic structural diagram of a second perovskite quantum dot micro light-emitting diode device provided in an embodiment of the present application;

[0024] Figure 3 It is a schematic structural diagram of a third perovskite quantum dot micro light-emitting diode device provided in an embodiment of the present application;

[0025] Figure 4It is a schematic diagram of carrier injection of the perovskite quantum dot micro light-emitting diode device prepared in Example 1 of the present application;

[0026] Figure 5 This is a schematic diagram of a perovskite quantum dot micro-pixel of a green perovskite quantum dot layer in a perovskite quantum dot micro-light-emitting diode device prepared in Example 1 of the present application;

[0027] Figure 6 This is an electroluminescence spectrum of the perovskite quantum dot micro-light-emitting diode device prepared in Example 1 of the present application;

[0028] Figure 7 This is an external quantum efficiency-voltage curve of the perovskite quantum dot micro light-emitting diode device prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, but the implementation methods of the present application are not limited thereto.

[0030] The words "preferably", "more preferably" and the like in this application refer to embodiments of the present invention that may provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or in other circumstances. In addition, the statement of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of this application.

[0031] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.

[0032] It should be noted that when a component is referred to as being "on another component," "connected to another component," "coupled to another component," or "contacting another component," it may be directly on, connected to, coupled to, or contacting the other component, or there may be intervening components. In contrast, when a component is referred to as being "directly on another component," "directly connected to," "directly coupled to," or "directly contacting" another component, there are no intervening components. Similarly, when a first component is referred to as being "electrically in contact with" or "electrically coupled to" a second component, there is an electrical path between the first component and the second component that allows current to flow. The electrical path may include capacitors, coupled inductors, and / or other components that allow current to flow, even without direct contact between conductive components.

[0033] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which this application belongs. The experimental reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the amounts of experimental reagents, unless otherwise specified, are all the amounts of reagents used in conventional experimental operations; and the experimental methods, unless otherwise specified, are all conventional methods.

[0034] The CdSe / ZnSe / ZnS core-shell quantum dot ink used in Comparative Example 1 is selected from Suzhou Xingshuo Nanotechnology Co., Ltd.

[0035] In the first aspect, an embodiment of the present application also provides a perovskite quantum dot micro light-emitting diode device, which includes a first electrode layer, an interface regulation layer, a perovskite array layer, an electron transport layer and a second electrode layer stacked in sequence; wherein the interface regulation layer is one of the first interface regulation layer, the second interface regulation layer or the third interface regulation layer; the perovskite array layer includes a red perovskite quantum dot layer, a green perovskite quantum dot layer and a blue perovskite quantum dot layer arranged in parallel.

[0036] Figure 1 It is a schematic structural diagram of the first perovskite quantum dot micro light-emitting diode device provided in an embodiment of the present application.

[0037] See also Figure 1 The perovskite quantum dot micro-light-emitting diode device of the embodiment of the present application includes a first electrode layer 101, an interface regulation layer 102, a perovskite array layer 103, an electron transport layer 104 and a second electrode layer 105 which are stacked in sequence; wherein the interface regulation layer 102 is a first interface regulation layer, wherein the first interface regulation layer includes a hole injection layer 1021 and a surface modification layer 1022. The perovskite array layer 103 includes a red perovskite quantum dot layer 1031, a green perovskite quantum dot layer 1032 and a blue perovskite quantum dot layer 1033 which are arranged in parallel.

[0038] Figure 2 It is a schematic diagram of the structure of the second perovskite quantum dot micro light-emitting diode device provided in the embodiment of the present application.

[0039] See also Figure 2 The perovskite quantum dot micro-light-emitting diode device of the embodiment of the present application includes a first electrode layer 101, an interface regulation layer 102, a perovskite array layer 103, an electron transport layer 104 and a second electrode layer 105 which are stacked in sequence; wherein the interface regulation layer 102 is a second interface regulation layer, wherein the second interface regulation layer includes a hole transport layer 1023 and a surface modification layer 1022. The perovskite array layer 103 includes a red perovskite quantum dot layer 1031, a green perovskite quantum dot layer 1032 and a blue perovskite quantum dot layer 1033 which are arranged in parallel.

[0040] Figure 3 It is a schematic structural diagram of the third perovskite quantum dot micro light-emitting diode device provided in an embodiment of the present application.

[0041] See also Figure 3 The perovskite quantum dot micro-light-emitting diode device of the embodiment of the present application includes a first electrode layer 101, an interface regulation layer 102, a perovskite array layer 103, an electron transport layer 104 and a second electrode layer 105 which are stacked in sequence; wherein the interface regulation layer 102 is a third interface regulation layer, wherein the third interface regulation layer includes a hole injection layer 1021, a hole transport layer 1023 and a surface modification layer 1022. The perovskite array layer 103 includes a red perovskite quantum dot layer, a green perovskite quantum dot layer and a blue perovskite quantum dot layer which are arranged in parallel.

[0042] In some embodiments, the first electrode layer is any one of ITO glass, FTO conductive glass substrate, ITO / FTO polyethylene naphthalate flexible substrate or ITO / FTO polyethylene terephthalate flexible substrate.

[0043] In some embodiments, the first electrode layer has a thickness of 0.1 to 3 mm and a resistance of 10 to 150 Ω. For example, the first electrode layer may have a thickness of 0.1, 1, 2, 3 nm, etc., and a resistance of 10, 20, 50, 100, 150 Ω, etc.

[0044] In some embodiments, the thickness of the electron transport layer is 2 to 200 nm. For example, the thickness of the electron transport layer can be 2, 10, 20, 50, 100, 150, 200 nm, etc.

[0045] In some embodiments, the thickness of the second electrode layer is 10-200 nm. For example, the thickness of the second electrode layer can be 10, 20, 30, 50, 100, 150, 200 nm, etc.

[0046] In some embodiments, the thickness of the perovskite array layer is 1 to 200 nm. For example, the thickness of the perovskite array layer can be 1, 5, 10, 20, 50, 100, 150, 200 nm, etc.

[0047] In a second aspect, this embodiment provides a method for preparing a perovskite quantum dot micro light emitting diode device, comprising the following steps:

[0048] S1. Prepare a first solution, a second solution, a surface modification solution and a perovskite quantum dot ink respectively and set them aside;

[0049] S2. sequentially coating the first solution and the surface modification solution on the surface of the first electrode layer to form a first interface regulation layer on the first electrode layer, or sequentially coating the second solution and the surface modification solution on the surface of the first electrode layer to form a second interface regulation layer on the first electrode layer; or sequentially coating the first solution, the second solution and the surface modification solution on the surface of the first electrode layer to form a third interface regulation layer on the first electrode layer;

[0050] S3, inkjet printing the perovskite quantum dot ink onto the first interface regulation layer to form a perovskite array layer on the first interface regulation layer; or, inkjet printing the perovskite quantum dot ink onto the second interface regulation layer to form a perovskite array layer on the second interface regulation layer; or, inkjet printing the perovskite quantum dot ink onto the third interface regulation layer to form a perovskite array layer on the third interface regulation layer; wherein the perovskite array layer includes a red perovskite quantum dot layer, a green perovskite quantum dot layer and a blue perovskite quantum dot layer arranged in parallel;

[0051] S4, evaporating an electron transport material onto the surface of the perovskite array layer to form an electron transport layer on the perovskite array layer;

[0052] S5. Evaporating the electrode material onto the surface of the electron transport layer to form a second electrode layer on the electron transport layer, thereby obtaining a perovskite quantum dot micro light emitting diode device.

[0053] The traditional method of preparing MicroLED (micro light-emitting diode) requires transferring a large number of three-color chips to the target display substrate through laser peeling and other methods. This process has extremely high requirements, and the speed of traditional mechanical transfer equipment can only reach dozens of chips per second. If you need to make a 4K TV, you need 26 million chips. Obviously, the traditional preparation method is difficult to meet mass production requirements.

[0054] The preparation method of the perovskite quantum dot micro light-emitting diode device provided in the embodiment of the present application is to first apply the first solution and the surface modification solution, or the second solution and the surface modification solution, or the first solution, the second solution and the surface modification solution on the surface of the first electrode layer to form a first interface regulation layer or a second interface regulation layer or a third interface regulation layer, and then inkjet print the perovskite quantum dot ink onto the first interface regulation layer or the second interface regulation layer or the third interface regulation layer. In this way, the perovskite quantum dot ink can be accurately deposited onto the first interface regulation layer or the second interface regulation layer or the third interface regulation layer to form a micro-sized emission pixel array (i.e., the perovskite array layer) with uniform brightness, and large-area full-color display can be achieved without using chip mass transfer technology, thereby overcoming the problem in the prior art that it is difficult to achieve full-color display due to the difficulty of chip mass transfer, and breaking the limitations of the application scenarios of traditional micro light-emitting diodes. At the same time, the preparation method provided in the present application has a simple process, and the light-emitting layer is a perovskite array layer. The materials used to prepare the perovskite array layer are widely available and inexpensive, which can greatly reduce the material and preparation costs and is conducive to the large-scale commercial application of micro light-emitting diodes.

[0055] The uniformity of the film (perovskite quantum dot micro-light-emitting diode device) will affect its luminous efficiency and luminous display effect. If the film is not uniform, there will be many bright and dark areas after lighting, and the luminous efficiency and luminous display effect will be poor. The embodiment of the present application can improve the uniformity of the film by setting the first interface regulation layer or the second interface regulation layer or the third interface regulation layer, thereby improving the luminous efficiency and luminous display effect of the device.

[0056] In some embodiments, in step S1, preparing a first solution specifically includes: dissolving a hole injection material in a first solvent to prepare a first solution with a mass concentration of 0.5 to 40 mg / mL; wherein the hole injection material is nickel oxide (NiO x ) precursor or at least one of a PEDOT:PSS aqueous solution with a mass fraction of 1% to 1.3%; the first solvent is at least one of water, ethanol, chlorobenzene or toluene. PEDOT:PSS is an aqueous solution of a high molecular polymer with high conductivity. According to different formulations, aqueous solutions with different conductivity can be obtained. PEDOT is a polymer of EDOT (3,4-ethylenedioxythiophene monomer) and PSS is polystyrene sulfonate.

[0057] In some embodiments, in step S1, preparing a second solution specifically includes: dissolving a hole transport material in a second solvent to prepare a second solution with a mass concentration of 0.5 to 40 mg / mL; wherein the hole transport material is CBP ((4,4'-di(9-carbazole)biphenyl), F8T2 (poly[[2,2'-bithiophene]-5,5'-diyl(9,9-dioctyl-9H-fluorene-2,7-diyl)]), TFB (poly[(9,9-dioctylfluorene The second solvent is at least one of chlorobenzene or toluene.

[0058] In some embodiments, in step S1, preparing a surface modification solution specifically includes:

[0059] The surface modification material is dissolved in a third solvent to prepare a surface modification solution with a mass concentration of 0.5 to 40 mg / mL; wherein the surface modification material is at least one of sodium dodecyl sulfate, ethoxylated polyethyleneimine, polyvinyl alcohol, polyethylene glycol, polyethyleneimine or sodium oleate; and the third solvent is at least one of N,N-dimethylformamide, dimethyl sulfoxide or ethanol.

[0060] In some embodiments, the first interface regulation layer includes a hole injection layer and a surface modification layer. In step S2, the first solution and the surface modification solution are sequentially coated on the surface of the first electrode layer to form the first interface regulation layer on the first electrode layer, specifically comprising:

[0061] Performing ultrasonic cleaning pretreatment on the first electrode layer to obtain a pretreated first electrode layer;

[0062] After coating the first solution on the surface of the pretreated first electrode layer, a first annealing treatment is performed to form a hole injection layer on the first electrode layer;

[0063] A second annealing treatment is performed after coating the surface modification solution on the surface of the hole injection layer to form a surface modification layer on the hole injection layer.

[0064] In some embodiments, the process conditions of the first annealing treatment are: heating at a temperature of 110-170° C. for 10-30 minutes. The process conditions of the second annealing treatment are: heating at a temperature of 100-150° C. for 10-30 minutes.

[0065] In some preferred embodiments, the process conditions of the first annealing treatment are: heating at a temperature of 140° C. for 15 minutes. The process conditions of the second annealing treatment are: heating at a temperature of 100° C. for 15 minutes.

[0066] In some embodiments, the first electrode layer (usually a transparent conductive substrate) can be ultrasonically cleaned using a cleaning agent, acetone, isopropanol, and anhydrous ethanol in sequence; the first electrode layer can also be ultrasonically cleaned multiple times using a cleaning agent and then ultrasonically cleaned using ethanol. After the ultrasonic cleaning is completed, the first electrode layer is placed in anhydrous ethanol for storage and standby use. When it is needed, the first electrode layer can be taken out of the anhydrous ethanol and placed in an oven for drying to remove the anhydrous ethanol on the surface of the first electrode layer, and then the dried first electrode layer is plasma cleaned for 5 to 40 minutes.

[0067] The above-mentioned cleaning agent can be detergent water, Deli cleaning agent aqueous solution or other optical glass cleaning agents.

[0068] By performing ultrasonic cleaning pretreatment on the first electrode layer, dust, grease and other stains on the surface of the first electrode layer can be removed.

[0069] In some other embodiments, the second interface regulation layer includes a hole transport layer and a surface modification layer. In step S2, the second solution and the surface modification solution are sequentially coated on the surface of the first electrode layer to form the second interface regulation layer on the first electrode layer, specifically comprising:

[0070] Performing ultrasonic cleaning pretreatment on the first electrode layer to obtain a pretreated first electrode layer;

[0071] After coating the second solution on the surface of the pretreated first electrode layer, a third annealing treatment is performed to form a hole transport layer on the first electrode layer;

[0072] The fourth annealing treatment is performed after the surface modification solution is applied on the surface of the hole transport layer to form a surface modification layer on the hole transport layer.

[0073] In some embodiments, the process conditions of the third annealing treatment are: heating at a temperature of 100-150° C. for 10-30 minutes. The process conditions of the fourth annealing treatment are: heating at a temperature of 100-150° C. for 10-30 minutes.

[0074] In some preferred embodiments, the process condition of the third annealing treatment is: heating at a temperature of 120° C. for 15 minutes. The process condition of the fourth annealing treatment is: heating at a temperature of 100° C. for 15 minutes.

[0075] In some other embodiments, the third interface regulation layer includes a hole injection layer, a hole transport layer and a surface modification layer. In step S2, the first solution, the second solution and the surface modification solution are sequentially coated on the surface of the first electrode layer to form a third interface regulation layer on the first electrode layer, comprising:

[0076] Performing ultrasonic cleaning pretreatment on the first electrode layer to obtain a pretreated first electrode layer;

[0077] After coating the first solution on the surface of the pretreated first electrode layer, a fifth annealing treatment is performed to form a hole injection layer on the first electrode layer;

[0078] After coating the second solution on the surface of the hole injection layer, a sixth annealing treatment is performed to form a hole transport layer on the hole injection layer;

[0079] The seventh annealing treatment is performed after the surface modification solution is applied on the surface of the hole transport layer to form a surface modification layer on the hole transport layer.

[0080] The process conditions of the fifth annealing treatment are: heating at a temperature of 140° C. for 15 minutes. The process conditions of the sixth annealing treatment are: heating at a temperature of 120° C. for 15 minutes. The process conditions of the seventh annealing treatment are: heating at a temperature of 100° C. for 15 minutes.

[0081] In some embodiments, the perovskite quantum dot ink includes red perovskite quantum dot ink, green perovskite quantum dot ink and blue perovskite quantum dot ink; the first interface regulation layer includes a first interface region, a second interface region and a third interface region arranged in parallel. In step S3, the perovskite quantum dot ink is inkjet printed on the first interface regulation layer to form a perovskite array layer on the first interface regulation layer, including:

[0082] inkjet printing a red perovskite quantum dot ink into the first interface region to form a red perovskite quantum dot layer on the first interface region;

[0083] inkjet printing a green perovskite quantum dot ink into the second interface region to form a green perovskite quantum dot layer on the second interface region;

[0084] The blue perovskite quantum dot ink is inkjet printed into the third interface region to form a blue perovskite quantum dot layer on the third interface region.

[0085] In a specific example, the preparation method of red perovskite quantum dots is as follows:

[0086] 800 mg Cs2CO3, 2.5 mL oleic acid (OA) and 40 mL 1-octadecene (1-ODE) were added to a four-necked flask, heated to 110°C under vacuum for 30 minutes, and then heated to 150°C in a nitrogen atmosphere for 2 hours to form a transparent cesium precursor solution. PbBr2 (23 mg) and PbI2 (58 mg) were added to another flask, mixed with 0.5 mL oleylamine (Oam), 0.5 mL oleic acid (OA), and 5 mL 1-octadecene (1-ODE), and vacuum dried at 120°C for 60 minutes to obtain a lead halide precursor. Maintaining a nitrogen atmosphere, 0.5 mL of cesium precursor solution was quickly injected into the flask containing the lead halide precursor. After reacting at a reaction temperature of 160°C for 10 seconds, a reaction solution was obtained. The reaction solution was then cooled to room temperature with an ice water bath, and then centrifuged at a speed of 7800 rpm for 5 minutes to remove unreacted precursors. The precipitate was collected and dispersed in toluene. The solution was centrifuged at a speed of 3000 rpm for 5 minutes, and the supernatant was collected to obtain red perovskite quantum dots.

[0087] In a specific example, the preparation method of blue perovskite quantum dots is as follows:

[0088] 800mg Cs2CO3, 2.5mL oleic acid (OA) and 40mL 1-octadecene (1-ODE) were added to a four-necked flask, heated to 110°C under vacuum for 30 minutes, and then heated to 150°C in a nitrogen atmosphere for 2h to form a transparent cesium precursor solution. PbBr2 (33mg), PbCl2 (27mg) were added to another flask, mixed with 0.5mL oleylamine (Oam), 0.5mL oleic acid (OA), and 5mL 1-octadecene (1-ODE), and vacuum dried at 120°C for 60 minutes to obtain a lead halide precursor. Maintaining a nitrogen atmosphere, 0.5 mL of cesium precursor solution was quickly injected into the flask containing the lead halide precursor. After reacting at a reaction temperature of 160°C for 10 seconds, a reaction solution was obtained. The reaction solution was then cooled to room temperature with an ice water bath, and then centrifuged at a speed of 7800 rpm for 5 minutes to remove unreacted precursors. The precipitate was collected and dispersed in toluene. The solution was centrifuged at a speed of 3000 rpm for 5 minutes, and the supernatant was collected to obtain blue perovskite quantum dots.

[0089] In a specific example, the preparation method of green perovskite quantum dots is as follows:

[0090] 800 mg Cs2CO3, 2.5 mL oleic acid (OA) and 40 mL 1-octadecene (1-ODE) were added to a four-necked flask, heated to 110°C under vacuum for 30 minutes, and then heated to 150°C in a nitrogen atmosphere for 2 hours to form a transparent cesium precursor solution. PbBr2 (69 mg) was added to another flask, mixed with 0.5 mL oleylamine (Oam), 0.5 mL oleic acid (OA), and 5 mL 1-octadecene (1-ODE), and vacuum dried at 120°C for 60 minutes to obtain a lead halide precursor. Maintaining a nitrogen atmosphere, 0.5 mL of cesium precursor solution was quickly injected into the flask containing the lead halide precursor. After reacting at a reaction temperature of 160°C for 10 seconds, a reaction solution was obtained. The reaction solution was then cooled to room temperature with an ice water bath, and then centrifuged at a speed of 7800 rpm for 5 minutes to remove unreacted precursors. The precipitate was collected and dispersed in toluene. The solution was centrifuged at a speed of 3000 rpm for 5 minutes, and the supernatant was collected to obtain green perovskite quantum dots.

[0091] In some embodiments, the red perovskite quantum dots prepared above can be purified. Specifically, the red perovskite quantum dots prepared above can be dispersed in 1 mL of toluene, and then 3 mL of ethyl acetate (EA) is added and vortexed for 1 minute to obtain a mixture; the mixture is centrifuged at a speed of 7800 rpm for 3 minutes, the first precipitate is collected and resuspended in 1 mL of toluene, and the above operation is repeated twice to obtain a second precipitate. The second precipitate is suspended in 1 mL of cyclohexylbenzene for ligand exchange to obtain a red perovskite quantum dot solution. 5 mg of PEABr (phenylethylamine bromide) and PEAI (phenylethylamine iodide) are dissolved in 0.5 mL of dimethylformamide (DMF) at a mass ratio of 1:2, and then diluted with 0.5 mL of cyclohexylbenzene to obtain a ligand solution. Take 100 μL of the ligand solution and add it to 1 mL of the red perovskite quantum dot solution. After vortexing for 1 minute, centrifuge at a speed of 4000 rpm for 2 minutes to remove any insoluble solids to obtain purified red perovskite quantum dots. Before storage or use, the purified red perovskite quantum dots can be centrifuged at 4000 rpm for 3 minutes to remove insoluble particles.

[0092] The green perovskite quantum dots and blue perovskite quantum dots prepared above can be purified by referring to the purification steps for the red perovskite quantum dots to obtain purified green perovskite quantum dots and purified blue perovskite quantum dots. The difference is that the ligand solution is 5 mg of PEABr (phenylethylamine bromide) dissolved in 0.5 mL of dimethylformamide (DMF).

[0093] In some embodiments, the steps of preparing red perovskite quantum dot ink are as follows: the purified red perovskite quantum dots are passivated using short-chain ligands, and then the passivated red perovskite quantum dots are dissolved in a perovskite ink solvent to obtain red perovskite quantum dot ink. Among them, the short-chain ligand is at least one of phenethylammonium bromide, ionic liquid surface ligands (such as hexafluorophosphoric acid, bistrifluoromethanesulfonyl imide, bistrifluoromethanesulfonyl imide), and short-chain chelating ligands (such as citric acid, etc.). The perovskite ink solvent is at least one of cyclohexylbenzene, o-dichlorobenzene, toluene, hexane, octane or dodecane.

[0094] Green perovskite quantum dot ink and blue perovskite quantum dot ink can be prepared by referring to the preparation steps of the red perovskite quantum dot ink.

[0095] In some embodiments, in step S2, the first solution can be coated on the surface of the first electrode layer by spin coating, blade coating, inkjet printing, spraying or vacuum evaporation, and then annealing is performed to form a hole injection layer on the first electrode layer.

[0096] In some embodiments, in step S2, the second solution can be coated on the surface of the first electrode layer by spin coating, blade coating, inkjet printing, spraying or vacuum evaporation, and then annealing is performed to form a hole transport layer on the first electrode layer.

[0097] In some embodiments, in step S2, the surface modification solution can be coated on the surface of the hole injection layer or the hole transport layer by spin coating, blade coating, inkjet printing, spraying or vacuum evaporation, and then annealing is performed to form a surface modification layer.

[0098] In some embodiments, the first electrode layer is any one of ITO glass, FTO conductive glass substrate, ITO / FTO polyethylene naphthalate flexible substrate or ITO / FTO polyethylene terephthalate flexible substrate.

[0099] In some embodiments, in step S3, the perovskite quantum dot ink may be inkjet printed onto the first interface regulation layer, the second interface regulation layer, or the third interface regulation layer using a piezoelectric inkjet method or an electrofluidic inkjet method.

[0100] In some embodiments, in step S4, the electron transport material is evaporated onto the surface of the perovskite array layer to form an electron transport layer on the perovskite array layer, comprising:

[0101] In an etching gas atmosphere, the device obtained after the inkjet printing process is subjected to ultraviolet-ozone plasma etching for 0.1 to 300 seconds to obtain an etched device; wherein the etching gas is at least one of air, oxygen, nitrogen, argon or helium;

[0102] The electron transport material is evaporated onto the surface of the etched device to form an electron transport layer on the perovskite array layer of the etched device.

[0103] By subjecting the device obtained after inkjet printing to ultraviolet-ozone plasma etching, the redundant interface regulation layer (the first interface regulation layer or the second interface regulation layer or the third interface regulation layer) can be removed to avoid the recombination of excitons in the hole transport layer, thereby eliminating the non-radiative recombination caused by the contact between the hole transport layer and the electron transport layer.

[0104] If the step of plasma etching the printed device is omitted, the entire surface of the device will emit light after it is lit, and individual pixels cannot be seen to emit light, which affects the light-emitting display effect of the device.

[0105] In some embodiments, the electron transport material is TPBi (1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene), BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), ZnO (zinc oxide), Mg:ZnO, B3PYMPM (4,6-bis(3,5-di(3-pyridyl)phenyl)-2-methylpyrimidine), BPhen (badophenanthroline), PBD (2-(4-tert- At least one of poly((1,2-butylphenyl)-5-biphenyloxadiazole), PFN (poly[(9,9-dioctyl-2,7-fluoro-naphthalene)-(9,9-bis(3-(N,N-dimethylamino)propyl))-2,7-fluorene)]), Ca(acac)2 (calcium acetylacetonate) or TmPyPB (3,3'-[5'-[3-(3-pyridyl)phenyl][1,1':3',1"-terphenyl]-3,3"-diyl]bipyridine).

[0106] In some embodiments, the electrode material is at least one of Al, LiF / Al, LiF / Ag, silver nanowires, In-Ga, copper, or gold.

[0107] In some embodiments, the first electrode layer has a thickness of 0.1 to 3 mm and a resistance of 10 to 150 Ω. For example, the first electrode layer may have a thickness of 0.1, 1, 2, 3 nm, etc., and a resistance of 10, 20, 50, 100, 150 Ω, etc.

[0108] In some embodiments, the thickness of the electron transport layer is 2 to 200 nm. For example, the thickness of the electron transport layer can be 2, 10, 20, 50, 100, 150, 200 nm, etc.

[0109] In some embodiments, the thickness of the second electrode layer is 10-200 nm. For example, the thickness of the second electrode layer can be 10, 20, 30, 50, 100, 150, 200 nm, etc.

[0110] In some embodiments, the thickness of the perovskite array layer is 1-200 nm. For example, the thickness of the perovskite array layer can be 1, 5, 10, 20, 50, 100, 150, 200 nm, etc.

[0111] The present application has been subjected to multiple tests, and part of the test results are now cited as references to further describe the invention in detail, which is described in detail below in conjunction with specific embodiments.

[0112] Example 1

[0113] The perovskite quantum dot micro-light emitting diode device of the embodiment of the present application is prepared by the following steps:

[0114] (1) Cleaning of the transparent conductive substrate (first electrode layer): The commercially etched 3.2 cm × 3.2 cm ITO glass was subjected to the following ultrasonic cleaning treatment: it was sequentially cleaned with an aqueous detergent solution for 30 min, acetone for 30 min, isopropanol for 30 min, deionized water for 30 min, and anhydrous ethanol for 30 min. The first electrode layer was then placed in an oven for drying to remove the anhydrous ethanol remaining on the surface of the first electrode layer. The dried first electrode layer was then plasma cleaned for 5 minutes and dried to obtain the pretreated ITO glass.

[0115] (2) Preparation of the third interface control layer: The hole injection material (PEDOT:PSS aqueous solution with a mass fraction of 1.3-1.7) is filtered through a 0.22 μm (or 0.45 μm) filter head, and the filtered first solution is spin-coated on the surface of the ITO glass pretreated in the above step (1). The spin coating parameters are a spin coating speed of 4000 rpm for 30 seconds; after spin coating, the solution is heated at a temperature of 140° C. for 15 minutes for annealing to form a hole injection layer on the ITO glass. The hole transport material PVK is dissolved in chlorobenzene to prepare a second solution with a mass concentration of 5 mg / mL. The second solution is filtered through a 0.22 μm (or 0.45 μm) filter head, and the filtered second solution is spin-coated on the above The surface of the hole injection layer is coated with a spin coating speed of 3000 rpm for 30 seconds; after the coating, the coating is heated at 120°C for 15 minutes for annealing to form a hole transport layer on the hole injection layer. The surface modification material (sodium dodecyl sulfate) is dissolved in dimethyl sulfoxide to prepare a surface modification solution with a mass concentration of 3 mg / mL; the surface modification solution is filtered using a 0.22 micron (or 0.45 micron) filter head to obtain a filtered surface modification solution; the filtered surface modification solution is then spin coated on the surface of the hole transport layer, and the spin coating parameters are 3000 rpm for 30 seconds; after the coating, the coating is heated at 100°C for 15 minutes for annealing to form a surface modification layer on the hole transport layer.

[0116] (3) Preparation of perovskite array layer: using a piezoelectric inkjet printer to inkjet print a pre-prepared red perovskite quantum dot ink into the first interface region of the third interface regulation layer to form a red perovskite quantum dot layer; using a piezoelectric inkjet printer to inkjet print a pre-prepared green perovskite quantum dot ink into the second interface region of the third interface regulation layer to form a green perovskite quantum dot layer; using a piezoelectric inkjet printer to inkjet print a pre-prepared blue perovskite quantum dot ink into the third interface region of the third interface regulation layer to form a blue perovskite quantum dot layer, thereby obtaining a printed device.

[0117] (4) Plasma etching treatment: The printed device obtained after the inkjet printing in the above step (3) is subjected to UV-ozone plasma etching treatment to obtain an etched device. The etching gas introduced is oxygen and the etching time is 10 s.

[0118] (5) Preparation of electron transport layer: The electron transport layer material TPBi is evaporated onto the surface of the perovskite array layer of the device after etching to form an electron transport layer. The thickness of the electron transport layer is 60 nm.

[0119] (6) Preparation of the second electrode layer: LiF was first evaporated on the electron transport layer in the above step (5) to a thickness of 1 nm, and then Al was evaporated on the LiF layer to a thickness of 150 nm to form a second electrode layer.

[0120] Figure 4 Schematic diagram of carrier injection of the perovskite quantum dot micro-light emitting diode device prepared in Example 1 of the present application. Figure 4 The electroluminescence principle of the perovskite quantum dot micro-LED device in the embodiment of the present application is as follows: holes and electrons enter the device from the positive and negative electrodes of the LED respectively, and are transported to the light-emitting layer through the carrier transport layer. Subsequently, holes and electrons are injected into the light-emitting layer from both sides, and finally the two carriers are combined in the light-emitting layer to form excitons, which undergo radiative recombination in the light-emitting layer, i.e., emit light.

[0121] Figure 5 This is a schematic diagram of the perovskite quantum dot micro-pixel of the green perovskite quantum dot layer in the perovskite quantum dot micro-light-emitting diode device prepared in Example 1 of the present application.

[0122] Figure 6 This is an electroluminescence spectrum of the perovskite quantum dot micro-LED device prepared in Example 1 of the present application. The electroluminescence spectrum was obtained by testing in a nitrogen glove box using an electroluminescence test system integrating a Keithley 2400 source meter, a PMA-12 spectrometer and an integrating sphere (Hamamatsu Photonics Co., Ltd, C9920-12). The full-color perovskite quantum dot micro-LED device has an electroluminescence spectrum half-peak width of less than 36nm, high color purity, and a color gamut coverage of 135% of the National Television Standards Committee (NTSC) standard, which is much wider than the color gamut of the color conversion micro-LED (114.4% NTSC).

[0123] Figure 7 This is the external quantum efficiency-voltage curve of the perovskite quantum dot micro-light-emitting diode device prepared in Example 1 of the present application. The external quantum efficiency was obtained by testing in a nitrogen glove box using an electroluminescence test system integrating a Keithley 2400 source meter, a PMA-12 spectrometer and an integrating sphere (Hamamatsu Photonics Co., Ltd, C9920-12). In addition, the maximum external quantum efficiencies of the red, green and blue perovskite quantum dot micro-light-emitting diode devices are 0.832%, 0.419% and 0.052%, respectively, and the external quantum efficiency of the red perovskite quantum dot micro-light-emitting diode device is much higher than that of red InGaN (0.18%) and AlInGaP (0.42%).

[0124] from Figure 6 and Figure 7It can be seen that the blue perovskite quantum dot layer in the perovskite quantum dot micro-light-emitting diode device prepared in Example 1 of the present application emits blue light with a main wavelength of 460nm under a DC power supply voltage of 4V, a half-width of 17.6nm, and a maximum external quantum efficiency of 0.052%; the green perovskite quantum dot layer emits green light with a main wavelength of 513nm under a DC power supply voltage of 5V, a half-width of 19nm, and a maximum external quantum efficiency of 0.419%; the red perovskite quantum dot layer emits green light with a main wavelength of 655nm under a DC power supply voltage of 6V, a half-width of 36nm, and a maximum external quantum efficiency of 0.832%.

[0125] Example 2

[0126] The preparation steps of the perovskite quantum dot micro-light-emitting diode device in the embodiment of the present application are basically the same as those in the above-mentioned embodiment 1, except that the transparent conductive substrate ITO glass in step (1) is replaced by FTO glass with a thickness of 2 mm.

[0127] Example 3

[0128] The preparation steps of the perovskite quantum dot micro-light-emitting diode device of the embodiment of the present application are basically the same as those of the above-mentioned embodiment 1, except that the hole transport material PVK in step (2) is replaced by Poly-TPD.

[0129] Comparative Example 1

[0130] The preparation steps of the micro-light emitting diode device of Comparative Example 1 are basically the same as those of the above-mentioned Example 1, except that the red perovskite quantum dot ink in step (3) is replaced by CdSe / ZnSe / ZnS core-shell quantum dot ink.

[0131] In summary, the preparation method provided in the embodiment of the present application has a simple process and can realize large-area full-color display without using chip mass transfer technology, which overcomes the problem of difficulty in realizing full-color display due to the difficulty of chip mass transfer in the prior art, and breaks the limitations of the application scenarios of traditional micro-light-emitting diodes. The prepared perovskite quantum dot micro-light-emitting diode device has high color purity and luminous efficiency, can realize large-area ultra-clear full-color flexible display, and has low cost, which is conducive to large-scale commercial application.

[0132] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A perovskite quantum dot micro light emitting diode device, characterized in that: The perovskite quantum dot micro light-emitting diode device comprises a first electrode layer, an interface regulation layer, a perovskite array layer, an electron transport layer and a second electrode layer which are stacked in sequence; Among them, the interface regulation layer is one of the first interface regulation layer, the second interface regulation layer or the third interface regulation layer; the perovskite array layer includes a red perovskite quantum dot layer, a green perovskite quantum dot layer and a blue perovskite quantum dot layer arranged in parallel.

2. The perovskite quantum dot micro light emitting diode device according to claim 1, characterized in that: The first electrode layer is any one of ITO glass, FTO conductive glass substrate, ITO / FTO polyethylene naphthalate flexible substrate or ITO / FTO polyethylene terephthalate flexible substrate.

3. The perovskite quantum dot micro light emitting diode device according to claim 1, characterized in that: The thickness of the first electrode layer is 0.1 to 3 mm, and the resistance is 10 to 150 Ω; The thickness of the electron transport layer is 2 to 200 nm; The thickness of the second electrode layer is 10 to 200 nm; The thickness of the perovskite array layer is 1-200 nm.

4. The method for preparing a perovskite quantum dot micro light emitting diode device according to claim 1, characterized in that: The steps include: Prepare a first solution, a second solution, a surface modification solution and a perovskite quantum dot ink respectively and set them aside; sequentially coating the first solution and the surface modification solution on the surface of the first electrode layer to form a first interface regulation layer on the first electrode layer, or sequentially coating the second solution and the surface modification solution on the surface of the first electrode layer to form a second interface regulation layer on the first electrode layer; or coating the first solution, the second solution and the surface modification solution on the surface of the first electrode layer in sequence to form a third interface regulation layer on the first electrode layer; Inkjet printing the perovskite quantum dot ink onto the first interface regulation layer to form a perovskite array layer on the first interface regulation layer; Alternatively, the perovskite quantum dot ink is inkjet printed onto the second interface regulation layer to form a perovskite array layer on the second interface regulation layer; Alternatively, the perovskite quantum dot ink is inkjet printed onto the third interface regulation layer to form a perovskite array layer on the third interface regulation layer; wherein the perovskite array layer comprises a red perovskite quantum dot layer, a green perovskite quantum dot layer and a blue perovskite quantum dot layer arranged in parallel; Evaporating an electron transport material onto the surface of the perovskite array layer to form an electron transport layer on the perovskite array layer; The electrode material is evaporated onto the surface of the electron transport layer to form a second electrode layer on the electron transport layer, thereby obtaining the perovskite quantum dot micro light emitting diode device.

5. The method for preparing a perovskite quantum dot micro light emitting diode device according to claim 4, characterized in that: Prepare a first solution, comprising: The hole injection material is dissolved in a first solvent to prepare a first solution with a mass concentration of 0.5 to 40 mg / mL; wherein the hole injection material is at least one of nickel oxide or a PEDOT:PSS aqueous solution with a mass fraction of 1% to 1.3%; and the first solvent is at least one of water, ethanol, chlorobenzene or toluene.

6. The method for preparing a perovskite quantum dot micro light emitting diode device according to claim 4, characterized in that: Prepare a second solution, comprising: The hole transport material is dissolved in a second solvent to prepare a second solution with a mass concentration of 0.5 to 40 mg / mL; wherein the hole transport material is at least one of CBP, F8, TFB, PVK, Poly-TPD, TAPC or TCTA; and the second solvent is at least one of chlorobenzene or toluene.

7. The method for preparing a perovskite quantum dot micro light emitting diode device according to claim 4, characterized in that: Prepare a surface modification solution including: The surface modification material is dissolved in a third solvent to prepare a surface modification solution with a mass concentration of 0.5 to 40 mg / mL; wherein the surface modification material is at least one of sodium dodecyl sulfate, ethoxylated polyethyleneimine, polyvinyl alcohol, polyethylene glycol, polyethyleneimine or sodium oleate; and the third solvent is at least one of N,N-dimethylformamide, dimethyl sulfoxide or ethanol.

8. The method for preparing a perovskite quantum dot micro light emitting diode device according to claim 4, characterized in that: The first interface regulation layer includes a hole injection layer and a surface modification layer; The first solution and the surface modification solution are sequentially coated on the surface of the first electrode layer to form a first interface regulation layer on the first electrode layer, comprising: Performing ultrasonic cleaning pretreatment on the first electrode layer to obtain a pretreated first electrode layer; After coating the first solution on the surface of the pretreated first electrode layer, a first annealing treatment is performed to form a hole injection layer on the first electrode layer; After the surface modification solution is applied on the surface of the hole injection layer, a second annealing treatment is performed to form a surface modification layer on the hole injection layer.

9. The method for preparing a perovskite quantum dot micro light emitting diode device according to claim 4, characterized in that: The perovskite quantum dot ink includes red perovskite quantum dot ink, green perovskite quantum dot ink and blue perovskite quantum dot ink; the first interface regulation layer includes a first interface region, a second interface region and a third interface region arranged in parallel; Inkjet printing the perovskite quantum dot ink onto the first interface regulation layer to form a perovskite array layer on the first interface regulation layer, comprising: Inkjet printing the red perovskite quantum dot ink onto the first interface region to form a red perovskite quantum dot layer on the first interface region; inkjet printing the green perovskite quantum dot ink onto the second interface region to form a green perovskite quantum dot layer on the second interface region; The blue perovskite quantum dot ink is inkjet printed onto the third interface region to form a blue perovskite quantum dot layer on the third interface region.

10. The method for preparing a perovskite quantum dot micro light emitting diode device according to claim 4, characterized in that: The method comprises: evaporating an electron transport material on the surface of the perovskite array layer to form an electron transport layer on the perovskite array layer, comprising: In an etching gas atmosphere, the device obtained after the inkjet printing process is subjected to ultraviolet-ozone plasma etching for 0.1 to 300 seconds to obtain an etched device; wherein the etching gas is at least one of air, oxygen, nitrogen, argon or helium; Evaporating an electron transport material on the surface of the etched device to form an electron transport layer on the perovskite array layer of the etched device; the electron transport material is at least one of TPBi, BCP, ZnO, Mg:ZnO, B3PYMPM, BPhen, PBD, PFN, Ca(acac)2 or TmPyPB; The electrode material is at least one of Al, LiF / Al, LiF / Ag, silver nanowires, In-Ga, copper or gold; The thickness of the first electrode layer is 0.1 to 3 mm, and the resistance is 10 to 150 Ω; The thickness of the electron transport layer is 2 to 200 nm; The thickness of the second electrode layer is 10 to 200 nm; The thickness of the perovskite array layer is 1-200 nm.

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