Air environment preparation method of perovskite blue light emitting diode

Abstract

The invention discloses an air environment preparation method of a perovskite blue light emitting diode. The air environment preparation method comprises the following steps: S1, preparing a hole injection layer on the surface of an ITO anode; s2, preparing an interface modification layer on the upper surface of the hole injection layer to obtain an intermediate substance; s3, preparing a perovskite blue light emitting layer on the interface modification layer to obtain a substrate with a light emitting layer; s4, evaporating an electron injection layer on the surface of the light-emitting layer; and S5, evaporating a cathode on the surface of the electron injection layer. An alkane anti-solvent (isooctane, n-octane and n-hexane) is introduced for treatment in the process of processing a light-emitting layer by a solution, so that the brightness and the electroluminescent external quantum efficiency of the device are improved, and compared with the traditional process of preparing blue light PELEDs in an air environment by adopting diethyl ether as a treatment solvent, the electroluminescent external quantum efficiency of the device is improved by about one time. The electroluminescent spectrum of the perovskite blue light PeLEDs disclosed by the invention can show relatively good stability under the driving of different voltages and time.

Description

Technical Field

[0001] The present invention belongs to the technical field of light-emitting diodes, and in particular relates to a method for preparing a perovskite blue light-emitting diode in an air environment. Background Art

[0002] Perovskite light-emitting diodes (PeLEDs) have made rapid progress in just a few years. They have the advantages of being economical, easily adjustable in luminescent color, high in color purity, and solution-processable. In the future, they are expected to show great potential in cheap, high-quality, large-size, flexible display and lighting applications.

[0003] In addition to the light-emitting layer material, the structure of PeLEDs is the same as that of organic light-emitting diodes and quantum dot light-emitting diodes, and is divided into upright structure and inverted structure. The upright structure usually adopts anode / hole injection layer / light-emitting layer / electron injection layer / cathode, and the inverted structure usually adopts a sandwich structure of cathode / electron injection layer / light-emitting layer / hole injection layer / anode. Electrode materials usually use indium-doped tin dioxide conductive glass (ITO), aluminum (Al) silver (Ag), gold (Au), etc. The hole injection layer usually uses poly (3,4-ethylenedioxythiophene): poly (styrene sulfonate) (PEDOT:PSS), nickel oxide (NiO x ), molybdenum oxide (MoO x ) etc. The electron injection layer is usually made of 1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene (TPBi), 1,3,5-tris[(3-pyridyl)-3-phenyl]benzene (TmPyPb), zinc oxide, etc.

[0004] Blue light is one of the three primary colors and plays an irreplaceable role in the future application of PeLEDs in flat panel displays and white light lighting. In the existing technology, the electroluminescence external quantum efficiency of blue light PeLEDs prepared in a non-air environment has exceeded 20%. However, blue light PeLEDs prepared in an air environment usually use ether or alcohol as a processing solvent, and the electroluminescence external quantum efficiency is only 3.02% (Adv. Sci. 2024, 2414499.), which is far behind in performance. Compared with a non-air environment, an air environment is more conducive to the large-scale preparation of PeLEDs and reduces manufacturing costs. In view of this, the preparation method of blue light PeLEDs in an air environment has important scientific significance and practical application value. Summary of the Invention

[0005] In order to solve the technical problems of low luminous efficiency and unstable luminous color of blue light PeLEDs prepared in an air environment in the prior art, the present invention provides an air environment preparation method for perovskite blue light emitting diodes.

[0006] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0007] The present invention provides an air environment preparation method for a perovskite blue light-emitting diode. The light-emitting diode has an upright structure and includes an anode, a hole injection layer, a light-emitting layer, an electron injection layer, and a cathode arranged in sequence from bottom to top. The method comprises the following steps:

[0008] S1. Preparation of hole injection layer on the surface of ITO anode

[0009] The patterned ITO anode was cleaned with alkali solution, deionized water, and alcohol in sequence, dried with nitrogen, and then cleaned with UV ozone for 400 seconds. The surface was then placed on the support of the spin coater. x ) aqueous solution is evenly coated on the ITO anode, the spin coating speed is 4000 rpm, the spin coating time is 40 seconds, and then 100 microliters of deionized water is evenly dropped on the nickel oxide (NiO x ) on the substrate, the spin coating rate was 5000 rpm, the spin coating time was 30 seconds, and a 10 nm thick hole injection layer was obtained; wherein nickel oxide (NiO x ) concentration was 30 mg / ml.

[0010] S2. Prepare an interface modification layer on the upper surface of the hole injection layer to obtain an intermediate substance

[0011] The filtered polyvinyl pyrrolidone solution was dissolved in N,N-dimethylformamide (DMF) solution, and the mixed solution was then evenly coated on the hole injection layer at a spin coating rate of 5000 rpm for 30 seconds. The mixture was then annealed on a hot plate at 120 degrees Celsius for 4 minutes to obtain an intermediate material, which, from top to bottom, consisted of an interface modification layer, a hole injection layer, and an ITO anode. The concentration of the polyvinyl pyrrolidone solution was 6 mg / ml.

[0012] S3. Prepare a perovskite blue light emitting layer on the interface modification layer to obtain a substrate with a light emitting layer

[0013] The intermediate material prepared in S2 was placed back on the spin coater, and the filtered perovskite precursor solution was immediately evenly coated on the interface modification layer at a spin coating rate of 4000 rpm for 110 seconds. Immediately after the 110th second, an antisolvent was added to the coating surface and the coating continued for another 40 seconds, for a total of 150 seconds. This was then annealed on a hot plate at 85°C for 40 seconds to obtain a 30-40nm thick perovskite blue light-emitting layer.

[0014] S4. Evaporating an electron injection layer on the surface of the light-emitting layer

[0015] The substrate with the light-emitting layer is placed in a vacuum coating machine, and TPBi is evaporated on the light-emitting layer at a certain rate under a certain vacuum degree as an electron injection layer.

[0016] S5. Evaporating a cathode on the surface of the electron injection layer

[0017] When LiF is deposited on the electron injection layer at a certain rate under a certain vacuum degree, and then Al is evaporated on LiF at a certain rate as the cathode under the same vacuum degree, the device structure is finally obtained as ITO / NIO x / Perovskite blue light emitting layer / TPBiP / LiF / Al blue light PeLEDs.

[0018] Furthermore, the anti-solvent in S3 is one of isooctane, n-octane or n-hexane, and the amount of the anti-solvent added is 200 μL.

[0019] Furthermore, the blue-light-emitting perovskite precursor solution is a dimethyl sulfoxide (DMSO) mixed solution of RbCl, CF3COOCs, CsBr, PbBr2, 18-crown-6, and triphenylphosphine oxide (TPPO). The molar ratio of RbCl, CF3COOCs, CsBr, and PbBr2 is 1:0.3:0.7:1, the concentration of 18-crown-6 is 5 mg / mL, and the concentration of triphenylphosphine oxide (TPPO) is 5 mg / mL. The mixed solution is stirred overnight at 65°C.

[0020] Furthermore, the ITO anode 1 has a square resistance of ≤15Ω / □, a transmittance of ≥86%, and a thickness of 135nm.

[0021] Furthermore, the vacuum degree of S4 is less than 5×10 -4 Pascal, the evaporation rate is 1-3 angstroms / second, and the thickness of the electron injection layer is 40-45 nm.

[0022] Furthermore, in S5 , during the Al evaporation process, the area of ​​the cathode is controlled by using a mask so that the effective light-emitting area of ​​the blue PeLEDs is 2×2 square millimeters.

[0023] Furthermore, the vacuum degree in S5 is lower than 5×10 -4 Pascal, the evaporation rate of LiF is 0.1-0.3 angstroms / second, the thickness of LiF is 1-5 nm, the evaporation rate of Al is 4-6 nanometers / minute, and the thickness of Al is 80-100 nm.

[0024] Furthermore, steps S1-S3 are all performed in an air environment with a humidity of 10-20%.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] 1. The present invention prepares perovskite blue light-emitting diodes in an air environment. By introducing alkane antisolvents (isooctane, n-octane, and n-hexane) during the solution processing of the light-emitting layer, the brightness and electroluminescence external quantum efficiency of the device are improved. Compared with the traditional process of preparing blue light PELEDs in an air environment using ether as a processing solvent, the electroluminescence external quantum efficiency of the device is increased by about one-fold.

[0027] 2. The electroluminescence spectrum of the perovskite blue light PeLEDs of the present invention can show good stability under different voltage and time driving. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the specific embodiments of the present invention, the following briefly introduces the drawings required for use in the specific embodiments. Obviously, the drawings described below are only some specific embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 This is a schematic structural diagram of the high-efficiency, color-stable perovskite blue light-emitting diode of the present invention.

[0030] Figure 2 1 is a graph showing the current density-voltage-brightness characteristics of the light-emitting devices in Comparative Example 1, Example 1, Example 2 and Example 3 of the present invention.

[0031] Figure 3 1 is a current efficiency-voltage characteristic diagram of the light-emitting devices in Comparative Example 1, Example 1, Example 2 and Example 3 of the present invention.

[0032] Figure 4 1 is a graph showing the electroluminescent external quantum efficiency-brightness characteristics of the light-emitting devices in Comparative Example 1, Example 1, Example 2 and Example 3 of the present invention.

[0033] Figure 5 Graphs showing normalized electroluminescence spectra of the light-emitting devices in Comparative Example 1, Example 1, Example 2, and Example 3 of the present invention.

[0034] Figure 6 These are electroluminescence spectra of the light-emitting devices in Comparative Example 1, Example 1, Example 2 and Example 3 of the present invention driven at different voltages.

[0035] Figure 7 These are electroluminescence spectra of the light-emitting devices in Comparative Example 1, Example 1, Example 2 and Example 3 of the present invention at different driving times.

[0036] In the figure, 1, anode, 2, hole injection layer, 3, interface modification layer, 4, light-emitting layer, 5, electron injection layer, 6, cathode. DETAILED DESCRIPTION

[0037] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with specific implementation methods.

[0038] The present invention presents a blue perovskite light-emitting diode structure prepared in an air environment. As shown in the figure, the diode has an upright structure, comprising, from bottom to top, an anode 1, a hole injection layer 2, an interface modification layer 3, a light-emitting layer 4, an electron injection layer 5, and a cathode 6. The light-emitting layer 4 is made of a blue perovskite material treated with different antisolvents, and the interface modification layer is made of polyvinyl pyrrolidone.

[0039] In the following examples, various processes and methods not described in detail are conventional methods known in the art. Unless otherwise specified, the materials, reagents, devices, instruments, equipment, etc. used in the following examples can be obtained from commercial sources.

[0040] Comparative Example 1

[0041] A method for preparing an air environment for a perovskite blue light-emitting diode comprises the following steps:

[0042] S1. Prepare a hole injection layer 2 on the surface of the ITO anode 1

[0043] The patterned ITO anode 1 was cleaned sequentially with alkaline solution, deionized water, and alcohol, dried with nitrogen, and then cleaned with UV-ozone for 400 seconds. The anode was then placed on a spin coater. A filtered nickel oxide (NiOx) aqueous solution was evenly spin-coated onto the anode at a speed of 4000 rpm for 40 seconds. 100 μL of deionized water was then evenly dropped onto the anode. The nickel oxide (NiOx) aqueous solution was then spin-coated onto the anode at a speed of 5000 rpm for 30 seconds, resulting in a 10 nm thick hole injection layer 2. The nickel oxide (NiOx) concentration was 30 mg / mL.

[0044] S2, prepare the interface modification layer 3 on the upper surface of the hole injection layer 2, thereby obtaining the intermediate material

[0045] The filtered polyvinyl pyrrolidone solution was dissolved in N,N-dimethylformamide (DMF) solution, and the mixed solution was then evenly coated on the hole injection layer 2 at a spin coating rate of 5000 rpm for 30 seconds. The mixture was then annealed on a hot plate at 120 degrees Celsius for 4 minutes to obtain an intermediate material, which, from top to bottom, consisted of an interface modification layer 3, a hole injection layer 2, and an ITO anode 1; wherein the concentration of the polyvinyl pyrrolidone solution was 6 mg / ml;

[0046] S3, preparing a perovskite blue light emitting layer 4 on the interface modification layer 3, thereby obtaining a substrate with a light emitting layer 4

[0047] The intermediate material prepared in S2 was placed back on the spin coater, and the filtered perovskite precursor solution was immediately evenly coated on the interface modification layer 3 at a spin coating rate of 4000 rpm for 110 seconds. Immediately after the 110th second, 200 μL of ether was added to the coated surface for solvent treatment. Spin coating continued for 40 seconds, for a total of 150 seconds. This was then annealed on a hot plate at 85°C for 40 seconds to obtain a 40 nm thick perovskite blue light-emitting layer 4.

[0048] S4, evaporating the electron injection layer 5 on the surface of the light-emitting layer 4

[0049] The substrate with the light-emitting layer 4 was placed in a vacuum coating machine at 5×10 -4 Below the Pascal vacuum, 45 nm TPBi was evaporated on the light-emitting layer 4 at a rate of 1 angstrom / second to form the electron injection layer 5 .

[0050] S5, evaporating the cathode 6 on the surface of the electron injection layer 5

[0051] When 5×10 -4 A 1 nm layer of LiF was evaporated onto the electron injection layer 5 at a rate of 0.1 angstroms / second under a vacuum below Pascal's degree. Then, a 100 nm layer of Al was evaporated onto the LiF at a rate of 4 nm / minute under the same vacuum, ultimately resulting in a blue PeLED with the structure of ITO / NIOx / perovskite blue light-emitting layer / TPBiP / LiF / Al. This is referred to as device 1. During the Al cathode deposition process, a mask was used to control the cathode area, resulting in an effective light-emitting area of ​​2 × 2 mm².

[0052] Wherein, steps S1-S3 are all performed in an air environment with a humidity of 10-20%.

[0053] The performance indicators of the blue light PeLEDs prepared in Comparative Example 1 are shown in Table 1, and the related current density-voltage-brightness characteristic diagram, current efficiency-voltage characteristic diagram, electroluminescence external quantum efficiency-brightness characteristic diagram, normalized electroluminescence spectrum diagram and electroluminescence spectrum diagrams under different driving voltages and times are shown in the attached figures. Figures 2 to 7 The device 1 curve is shown.

[0054] Example 1

[0055] A method for preparing an air environment for a perovskite blue light-emitting diode comprises the following steps:

[0056] S1. Prepare a hole injection layer 2 on the surface of the ITO anode 1

[0057] The patterned ITO anode 1 was cleaned sequentially with alkaline solution, deionized water, and alcohol, dried with nitrogen, and then cleaned with UV-ozone for 400 seconds. The anode was then placed on a spin coater. A filtered nickel oxide (NiOx) aqueous solution was evenly spin-coated onto the anode at a speed of 4000 rpm for 40 seconds. 100 μL of deionized water was then evenly dropped onto the anode. The nickel oxide (NiOx) aqueous solution was then spin-coated onto the anode at a speed of 5000 rpm for 30 seconds, resulting in a 10 nm thick hole injection layer 2. The nickel oxide (NiOx) concentration was 30 mg / mL.

[0058] S2, prepare the interface modification layer 3 on the upper surface of the hole injection layer 2, thereby obtaining the intermediate material

[0059] The filtered polyvinyl pyrrolidone solution was dissolved in N,N-dimethylformamide (DMF) solution, and the mixed solution was then evenly coated on the hole injection layer 2 at a spin coating rate of 5000 rpm for 30 seconds. The mixture was then annealed on a hot plate at 120 degrees Celsius for 4 minutes to obtain an intermediate material, which, from top to bottom, consisted of an interface modification layer 3, a hole injection layer 2, and an ITO anode 1; wherein the concentration of the polyvinyl pyrrolidone solution was 6 mg / ml;

[0060] S3, preparing a perovskite blue light emitting layer 4 on the interface modification layer 3, thereby obtaining a substrate with a light emitting layer 4

[0061] The intermediate material prepared in S2 was placed back on the spin coater, and the filtered perovskite precursor solution was immediately evenly coated on the interface modification layer 3 at a spin coating rate of 4000 rpm for 110 seconds. Immediately after the 110th second, 200 μL of isooctane was added to the spin-coated surface for solvent treatment. Spin coating continued for 40 seconds, for a total of 150 seconds. This was then annealed on a hot plate at 85°C for 40 seconds to obtain a 40 nm thick perovskite blue light-emitting layer 4.

[0062] S4, evaporating the electron injection layer 5 on the surface of the light-emitting layer 4

[0063] The substrate with the light-emitting layer 4 was placed in a vacuum coating machine at 5×10 -4 Below the Pascal vacuum, 45 nm TPBi was evaporated on the light-emitting layer 4 at a rate of 1 angstrom / second to form the electron injection layer 5 .

[0064] S5, evaporating the cathode 6 on the surface of the electron injection layer 5

[0065] When 5×10 -4 Below a Pascal vacuum, 1 nm of LiF was evaporated onto the electron injection layer 5 at a rate of 0.1 angstroms / second. Then, under the same vacuum, 100 nm of Al was evaporated onto the LiF as the cathode 6 at a rate of 4 nm / minute. This resulted in a blue PeLED with a device structure of ITO / NIOx / perovskite blue light-emitting layer / TPBiP / LiF / Al. This is referred to as device 2. During the Al cathode deposition process, a mask was used to control the cathode area, resulting in an effective light-emitting area of ​​2 × 2 mm².

[0066] Wherein, steps S1-S3 are all performed in an air environment with a humidity of 10-20%.

[0067] The performance indicators of the blue light PeLEDs prepared in Example 1 are shown in Table 1, and the related current density-voltage-brightness characteristic diagram, current efficiency-voltage characteristic diagram, electroluminescence external quantum efficiency-brightness characteristic diagram, normalized electroluminescence spectrum diagram and electroluminescence spectrum diagrams under different driving voltages and times are shown in the attached figures. Figures 2 to 7 The device 2 curve is shown.

[0068] Example 2

[0069] A method for preparing an air environment for a perovskite blue light-emitting diode comprises the following steps:

[0070] S1. Prepare a hole injection layer 2 on the surface of the ITO anode 1

[0071] The patterned ITO anode 1 was cleaned sequentially with alkaline solution, deionized water, and alcohol, dried with nitrogen, and then cleaned with UV-ozone for 400 seconds. The anode was then placed on a spin coater. A filtered nickel oxide (NiOx) aqueous solution was evenly spin-coated onto the anode at a speed of 4000 rpm for 40 seconds. 100 μL of deionized water was then evenly dropped onto the anode. The nickel oxide (NiOx) aqueous solution was then spin-coated onto the anode at a speed of 5000 rpm for 30 seconds, resulting in a 10 nm thick hole injection layer 2. The nickel oxide (NiOx) concentration was 30 mg / mL.

[0072] S2, prepare the interface modification layer 3 on the upper surface of the hole injection layer 2, thereby obtaining the intermediate material

[0073] The filtered polyvinyl pyrrolidone solution was dissolved in N,N-dimethylformamide (DMF) solution, and the mixed solution was then evenly coated on the hole injection layer 2 at a spin coating rate of 5000 rpm for 30 seconds. The mixture was then annealed on a hot plate at 120 degrees Celsius for 4 minutes to obtain an intermediate material, which, from top to bottom, consisted of an interface modification layer 3, a hole injection layer 2, and an ITO anode 1; wherein the concentration of the polyvinyl pyrrolidone solution was 6 mg / ml;

[0074] S3, preparing a perovskite blue light emitting layer 4 on the interface modification layer 3, thereby obtaining a substrate with a light emitting layer 4

[0075] The intermediate material prepared in S2 was placed back on the spin coater, and the filtered perovskite precursor solution was immediately evenly coated on the interface modification layer 3 at a spin coating rate of 4000 rpm for 110 seconds. Immediately after the 110th second, 200 μL of n-octane was added to the spin-coated surface for solvent treatment. Spin coating was continued for 40 seconds, for a total spin coating time of 150 seconds. This was then annealed on a hot plate at 85°C for 40 seconds to obtain a 40 nm thick perovskite blue light-emitting layer 4.

[0076] S4, evaporating the electron injection layer 5 on the surface of the light-emitting layer 4

[0077] The substrate with the light-emitting layer 4 was placed in a vacuum coating machine at 5×10 -4 Below the Pascal vacuum, 45 nm TPBi was evaporated on the light-emitting layer 4 at a rate of 1 angstrom / second to form the electron injection layer 5 .

[0078] S5, evaporating the cathode 6 on the surface of the electron injection layer 5

[0079] When 5×10 -4Below a Pascal vacuum, 1 nm of LiF was evaporated onto the electron injection layer 5 at a rate of 0.1 angstroms / second. Then, under the same vacuum, 100 nm of Al was evaporated onto the LiF as the cathode 6 at a rate of 4 nm / minute. This resulted in a blue PeLED with a device structure of ITO / NIOx / perovskite blue light-emitting layer / TPBiP / LiF / Al. This is referred to as device 3. During the Al cathode deposition process, a mask was used to control the cathode area, resulting in an effective light-emitting area of ​​2 × 2 mm².

[0080] Wherein, steps S1-S3 are all performed in an air environment with a humidity of 10-20%.

[0081] The performance indicators of the blue PeLEDs prepared in Example 2 are shown in Table 1, and the related current density-voltage-brightness characteristic diagram, current efficiency-voltage characteristic diagram, electroluminescence external quantum efficiency-brightness characteristic diagram, normalized electroluminescence spectrum diagram and electroluminescence spectrum diagrams under different driving voltages and times are shown in the attached figures. Figures 2 to 7 The device 3 curve is shown.

[0082] Example 3

[0083] A method for preparing an air environment for a perovskite blue light-emitting diode comprises the following steps:

[0084] S1. Prepare a hole injection layer 2 on the surface of the ITO anode 1

[0085] The patterned ITO anode 1 was cleaned sequentially with alkaline solution, deionized water, and alcohol, dried with nitrogen, and then cleaned with UV-ozone for 400 seconds. The anode was then placed on a spin coater. A filtered nickel oxide (NiOx) aqueous solution was evenly spin-coated onto the anode at a speed of 4000 rpm for 40 seconds. 100 μL of deionized water was then evenly dropped onto the anode. The nickel oxide (NiOx) aqueous solution was then spin-coated onto the anode at a speed of 5000 rpm for 30 seconds, resulting in a 10 nm thick hole injection layer 2. The nickel oxide (NiOx) concentration was 30 mg / mL.

[0086] S2, prepare the interface modification layer 3 on the upper surface of the hole injection layer 2, thereby obtaining the intermediate material

[0087] The filtered polyvinyl pyrrolidone solution was dissolved in N,N-dimethylformamide (DMF) solution, and the mixed solution was then evenly coated on the hole injection layer 2 at a spin coating rate of 5000 rpm for 30 seconds. The mixture was then annealed on a hot plate at 120 degrees Celsius for 4 minutes to obtain an intermediate material, which, from top to bottom, consisted of an interface modification layer 3, a hole injection layer 2, and an ITO anode 1; wherein the concentration of the polyvinyl pyrrolidone solution was 6 mg / ml;

[0088] S3, preparing a perovskite blue light emitting layer 4 on the interface modification layer 3, thereby obtaining a substrate with a light emitting layer 4

[0089] The intermediate material prepared in S2 was placed back on the spin coater, and the filtered perovskite precursor solution was immediately evenly coated on the interface modification layer 3 at a spin coating rate of 4000 rpm for 110 seconds. Immediately after the 110th second, 200 μL of n-hexane was added dropwise to the coated surface for solvent treatment. Spin coating continued for 40 seconds, for a total of 150 seconds. This was then annealed on a hot plate at 85°C for 40 seconds to obtain a 40 nm thick perovskite blue light-emitting layer 4.

[0090] S4, evaporating the electron injection layer 5 on the surface of the light-emitting layer 4

[0091] The substrate with the light-emitting layer 4 was placed in a vacuum coating machine at 5×10 -4 Below the Pascal vacuum, 45 nm TPBi was evaporated on the light-emitting layer 4 at a rate of 1 angstrom / second to form the electron injection layer 5 .

[0092] S5, evaporating the cathode 6 on the surface of the electron injection layer 5

[0093] When 5×10 -4 Below Pascal vacuum, 1 nm of LiF was evaporated on the electron injection layer 5 at a rate of 0.1 angstroms / second, and then 100 nm of Al was evaporated on the LiF as the cathode 6 at the same vacuum degree at a rate of 4 nanometers / minute, finally obtaining a device structure of ITO / NIOx / perovskite blue light emitting layer / TPBiP / LiF / Al blue light PeLEDs.

[0094] This is referred to as device 4. During the process of evaporating Al as the cathode, a mask was used to control the area of ​​the cathode, so that the effective light-emitting area of ​​the blue PeLEDs was 2×2 square millimeters.

[0095] Wherein, steps S1-S3 are all performed in an air environment with a humidity of 10-20%.

[0096] The performance indicators of the blue PeLEDs prepared in Example 3 are shown in Table 1, and the related current density-voltage-brightness characteristic diagram, current efficiency-voltage characteristic diagram, electroluminescence external quantum efficiency-brightness characteristic diagram, normalized electroluminescence spectrum diagram and electroluminescence spectrum diagrams under different driving voltages and times are shown in the attached figures. Figures 2 to 7 The device 4 curve is shown.

[0097] Table 1

[0098]

[0099] As can be seen from Table 1, the brightness, current efficiency, and electroluminescent external quantum efficiency of the device obtained by treating the light-emitting layer 2 with an alkane antisolvent (Example 3) of the high-efficiency and stable perovskite blue light-emitting diode prepared in an air environment of the present invention are nearly doubled compared to the untreated device (Comparative Example 3).

[0100] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a perovskite blue light emitting diode in an air environment, characterized in that: The steps include: S1, preparing a hole injection layer (2) on the surface of an ITO anode (1); S2, preparing an interface modification layer (3) on the upper surface of the hole injection layer (2), thereby obtaining an intermediate substance; S3, preparing a perovskite blue light emitting layer (4) on the interface modification layer (3), thereby obtaining a substrate with the light emitting layer (4); S4, evaporating an electron injection layer (5) on the surface of the light-emitting layer (4); S5. Vapor-depositing a cathode (6) on the surface of the electron injection layer (5).

2. The method for preparing an air environment of a perovskite blue light emitting diode according to claim 1, wherein: The antisolvent in S3 is one of isooctane, n-octane or n-hexane, and the amount of the antisolvent added is 200 μL.

3. The method for preparing an air environment of a perovskite blue light emitting diode according to claim 1, wherein: The blue-light-emitting perovskite precursor solution is a dimethyl sulfoxide (DMSO) mixed solution of RbCl, CF3COOCs, CsBr, PbBr2, 18-crown-6 and triphenylphosphine oxide (TPPO). The molar ratio of RbCl, CF3COOCs, CsBr and PbBr2 is 1:0.3:0.7:1, the concentration of 18-crown-6 is 5 mg / ml, and the concentration of triphenylphosphine oxide (TPPO) is 5 mg / ml. The mixed solution needs to be stirred overnight at 65 degrees Celsius.

4. The method for preparing an air environment of a perovskite blue light emitting diode according to claim 1, wherein: The ITO anode 1 has a square resistance of ≤15Ω / □, a transmittance of ≥86%, and a thickness of 135nm.

5. The method for preparing an air environment of a perovskite blue light emitting diode according to claim 1, wherein: S4 vacuum degree is less than 5×10 -4 Pascal, the evaporation rate is 1-3 angstroms / second, and the thickness of the electron injection layer (5) is 40-45 nm.

6. The method for preparing an air environment of a perovskite blue light emitting diode according to claim 1, wherein: In S5 , during the Al evaporation process, a mask is used to control the area of ​​the cathode so that the effective light-emitting area of ​​the blue PeLEDs is 2×2 square millimeters.

7. The method for preparing an air environment of a perovskite blue light emitting diode according to claim 1, wherein: The vacuum degree in S5 is less than 5×10 -4 Pascal, the evaporation rate of LiF is 0.1-0.3 angstroms / second, the thickness of LiF is 1-5 nm, the evaporation rate of Al is 4-6 nanometers / minute, and the thickness of Al is 80-100 nm.

8. The method for preparing an air environment of a perovskite blue light emitting diode according to claim 1, wherein: Steps S1-S3 are all performed in an air environment with a humidity of 10-20%.

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