A method for preparing a perovskite light-emitting diode by a low-pressure auxiliary solution method

Abstract

The application discloses a method for preparing a perovskite light-emitting diode by a low-pressure auxiliary solution method and belongs to the technical field of light-emitting diodes. ‑1 The perovskite light-emitting diode structure with an interface layer comprises an anode substrate, a hole transport layer, a perovskite light-emitting layer, an interface layer, an electron transport layer, a cathode modification layer and a cathode which are sequentially arranged on the anode substrate. The application introduces a low-pressure treated polymer interface layer, optimizes the interface layer under a low pressure of 1*10 ‑1 mbar by using different treatment times, thereby successfully avoiding a traditional high-temperature annealing process. The method not only solves the problem of film solidification but also effectively prevents the erosion of the upper solvent on the light-emitting layer, thereby inhibiting the interface loss, significantly improving the electron transport efficiency and the recombination light-emitting performance, and obtaining the enhanced electro-optical conversion efficiency and the stable perovskite light-emitting device.

Description

Technical Field

[0001] The invention belongs to the technical field of photoelectric materials and relates to a method for preparing a perovskite light-emitting diode using a low-pressure assisted solution method. Background Art

[0002] Perovskite light-emitting diodes (PeLEDs) are a novel electro-optical conversion technology based on perovskite luminescent layers. With their high extinction coefficient, high carrier mobility, high quantum efficiency, tunable bandgap, low material cost, and compatibility with roll-to-roll processing, they hold great potential for applications in near-infrared displays, communications, and biology. However, most PeLEDs utilize an electron transport layer (ETL) deposited on top of the perovskite layer via thermal deposition. To achieve low-cost PeLEDs and scalable fabrication, a fully solution-based device process is a pressing challenge.

[0003] While the solution-based method for preparing perovskite light-emitting diodes offers numerous advantages, it also inevitably encounters challenges. For example, the difficulty in manipulating the morphology and structure of perovskite nanocrystals directly impacts device performance. The large amount of organic solvents required in the preparation process not only increases costs but also poses environmental risks. Certain solvents can corrode the perovskite layer, causing severe photoluminescence quenching, which in turn impairs device performance and stability, severely limiting widespread application of PeLEDs.

[0004] Furthermore, research on improving effective carrier injection and transport, designing efficient light-emitting layer structures, and optimizing interface energy levels provides valuable scientific guidance for improving PeLED device performance. Because the perovskite light-emitting layer is crucial for device electro-optical conversion, achieving effective composite luminescence by suppressing crystal defects in the light-emitting layer and improving the balanced transport of carriers in the semiconductor functional layer is crucial for the development of low-cost PeLEDs. Summary of the Invention

[0005] The present invention aims to address the problems and deficiencies of the aforementioned prior art. It provides a method for preparing perovskite light-emitting diodes using a low-pressure-assisted solution process. This method addresses the luminescence quenching caused by internal defects and non-radiative losses due to carrier imbalance in the prior art solution-processed perovskite light-emitting diodes. It also improves the energy relationships between the functional layers, thereby enhancing the device's luminous efficiency.

[0006] In a first aspect, the present invention provides a method for preparing a perovskite light-emitting diode by a low-pressure assisted solution process, comprising: providing an interface layer between a perovskite light-emitting layer and an electron transport layer of the perovskite light-emitting diode;

[0007] The PEI organic solution was spin-coated on the perovskite light-emitting layer, so that the gas pressure was reduced to 1×10 -1mbar or less, maintain the air pressure, and let it stand and dry to obtain the interface layer.

[0008] Furthermore, the present invention dissolves PEI in isopropanol to obtain the PEI organic solution, and the concentration of the PEI organic solution is 0.2 mg / mL;

[0009] The spin coating has a rotation speed of 2000 to 5000 rpm / min and a spin coating time of 50 to 60 s;

[0010] The static drying time is 0.5 to 1 hour.

[0011] Furthermore, the present invention adopts a solution method to sequentially spin-coat a hole transport layer, a perovskite light-emitting layer, an interface layer and an electron transport layer on an anode substrate;

[0012] Then, a cathode modification layer and a cathode are sequentially vacuum-evaporated on the electron transport layer.

[0013] Furthermore, the anode substrate of the present invention is sequentially ultrasonically cleaned with deionized water, anhydrous ethanol, acetone, and isopropyl alcohol for at least 20 to 30 minutes each;

[0014] Then, the anode substrate is subjected to surface treatment;

[0015] The surface treatment is any one of plasma bombardment surface treatment and ultraviolet light treatment.

[0016] Furthermore, the hole transport layer of the present invention is prepared by spin coating PEDOT:PSS and then annealing;

[0017] The PEDOT:PSS solution was ultrasonically mixed with water in a volume ratio of 1:1 for 2 hours.

[0018] The spin coating speed is 2000-4000 rpm / min, and the spin coating time is 50-60 s;

[0019] The annealing temperature is 130-150° C., the annealing time is 15-20 minutes, and the annealing environment is air.

[0020] Furthermore, the perovskite light-emitting layer of the present invention is prepared by spin coating a perovskite precursor solution and then heat treating it;

[0021] The perovskite precursor solution is prepared by dissolving CsBr, PbBr2 and P123 in DMF or DMSO;

[0022] The spin coating speed is 2000-4000 rpm / min, the spin coating time is 50-60 s, and the spin coating environment is nitrogen;

[0023] The heat treatment temperature is 50-80° C., the heat treatment time is 1-3 minutes, and the heat treatment environment is nitrogen.

[0024] The mass ratio of the CsBr, PbBr2 and P123 is 8.33:8.3:0.3.

[0025] Furthermore, the electron transport layer of the present invention is prepared by spin coating of TPBi solution;

[0026] The TPBi solution is TPBi dissolved in DMF or DMSO, and the concentration of the TPBi solution is 3-5 mg / mL;

[0027] The spin coating has a rotation speed of 1000 to 3000 rpm / min, and the spin coating time is 50 to 65 s.

[0028] Furthermore, the cathode modification layer of the present invention is LiF, and the thickness of the cathode modification layer is 0.3 to 1 nm;

[0029] The cathode is made of any one of metal silver and aluminum, and the thickness of the cathode is 80-150 nm.

[0030] Furthermore, the present invention provides a method for preparing a perovskite light-emitting diode using a low-pressure assisted solution method, the specific steps of which are as follows:

[0031] S1. The anode substrate is an ITO substrate or an FTO substrate. The anode substrate is placed in deionized water, anhydrous ethanol, acetone, and isopropanol for ultrasonic cleaning in sequence. Each ultrasonic cleaning time is 20 to 30 minutes. After the ultrasonic cleaning is completed, the anode substrate is dried. The dried anode substrate is then surface treated, i.e., plasma bombardment surface treatment or ultraviolet light treatment, to achieve further cleaning.

[0032] S2. Ultrasonic mix the PEDOT:PSS solution with water at a volume ratio of 1:1 for 2 hours. Filter the mixed PEDOT:PSS solution through a 0.22 μm aqueous filter and apply it dropwise to the anode substrate. Then, spin coat the solution to form a hole transport layer thin film at a speed of 2000–4000 rpm / min for 50–60 seconds. After spin coating, anneal the film in air at 130–150°C for 15–20 minutes.

[0033] S3. Prepare a perovskite precursor solution by dissolving CsBr, PbBr2, and P123 in N,N-dimethylformamide or dimethyl sulfoxide in a mass ratio of 8.33:8.3:0.3. In a nitrogen atmosphere in a glove box, spin-coat the perovskite precursor solution at a speed of 2000–4000 rpm / min for 50–60 seconds. After spin-coating, heat-treat the substrate in a nitrogen atmosphere at 50–80°C for 1–3 minutes.

[0034] S4. PEI organic solution is PEI dissolved in isopropanol at a concentration of 0.2 mg / mL. The PEI organic solution is spin-coated at a speed of 2000-5000 rpm / min for 50-65 s. After spin-coating, vacuum treatment is performed for 5-30 min to a pressure of 1×10 -1 mbar, and then let it stand in a vacuum environment for 0.5 to 1 hour.

[0035] S5. TPBi solution is prepared by dissolving TPBi in DMF or DMSO, with a TPBi solution concentration of 3-5 mg / mL. The TPBi solution is spin-coated at a speed of 1000-3000 rpm / min for 50-60 s.

[0036] S6. Vacuum-deposit a cathode modification layer of LiF with a thickness of 0.3-1 nm. Vacuum-deposit a cathode of metallic silver or aluminum with a thickness of 80-150 nm.

[0037] In a second aspect, the present invention provides a perovskite light emitting diode.

[0038] Furthermore, the perovskite light-emitting diode of the present invention includes a hole transport layer, a perovskite light-emitting layer, an interface layer, an electron transport layer, a cathode modification layer and a cathode, which are sequentially arranged on an anode substrate.

[0039] Compared with the prior art, the technical solution provided by the present invention has at least the following beneficial effects or advantages:

[0040] The present invention introduces a low-pressure processed polymer interface layer technology to achieve a 1×10 -1In a low-pressure environment of 100 mbar, the low-pressure treatment time is finely regulated and optimized. This method effectively avoids the high-energy-consuming high-temperature annealing treatment step in the traditional process, solves the technical problem of thin film curing, and effectively prevents the electron transport layer from eroding the perovskite light-emitting layer. In addition, the method described in the present invention also suppresses the interface loss phenomenon, significantly improves the electron transport efficiency and composite luminescence performance. The perovskite light-emitting device prepared by the method described in the present invention not only has high electro-optical conversion efficiency, but also has excellent stability. The present invention achieves precise optimization of the interface layer performance by precisely controlling the treatment time and low-pressure environment, simplifies the preparation process of perovskite light-emitting diodes, and reduces the preparation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the structure of a perovskite light-emitting diode.

[0042] Figure 2 Schematic diagram of the structure of PEI molecule.

[0043] Figure 3 This is the JV curve of the perovskite light-emitting diode.

[0044] Figure 4 This is the LV curve of the perovskite light-emitting diode. DETAILED DESCRIPTION

[0045] The technical solutions of the present invention are described below with reference to the following examples. However, the present invention is not limited to the following examples. The experimental methods and detection methods described in each example are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified.

[0046] Example 1

[0047] This embodiment provides a method for preparing a perovskite light-emitting diode using a low-pressure assisted solution method.

[0048] This embodiment provides a perovskite light emitting diode, such as Figure 1 As shown, the structure of the perovskite light-emitting diode includes: a hole transport layer, a perovskite light-emitting layer, an interface layer, an electron transport layer, a cathode modification layer and a cathode sequentially arranged on the anode substrate; each functional layer of the perovskite light-emitting diode described in this embodiment is made by solution spin coating.

[0049] The method for preparing the perovskite light-emitting diode described in this embodiment includes the following steps:

[0050] (1) Cleaning and drying the anode substrate;

[0051] (2) spin coating PEDOT:PSS on the surface of the anode substrate described in step (1) and annealing to obtain a hole transport layer;

[0052] (3) spin-coating a perovskite precursor solution on the hole transport layer described in step (2), and obtaining a perovskite light-emitting layer after heat treatment;

[0053] (4) spin coating the PEI organic solution on the perovskite light-emitting layer described in step (3), and then vacuum drying to obtain an interface layer;

[0054] (5) spin coating the TPBi solution on the interface layer described in step (4) to prepare an electron transport layer;

[0055] (6) Vacuum evaporating a cathode modification layer and a cathode on the electron transport layer described in step (5).

[0056] The anode substrate in step (1) is an ITO substrate or an FTO substrate, and the anode substrate is placed in deionized water, anhydrous ethanol, acetone and isopropanol in sequence for ultrasonic cleaning, with each ultrasonic cleaning time being 20 to 30 minutes. After the ultrasonic cleaning is completed, the anode substrate is dried, and then the dried anode substrate is surface treated, i.e., plasma bombardment surface treatment or ultraviolet light treatment, to achieve further cleaning.

[0057] The PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate)) in step (2) is a PEDOT:PSS solution and water in a volume ratio of 1:1, which is ultrasonically mixed for 2 hours. The mixed PEDOT:PSS solution is filtered through a 0.22 μm aqueous filter and then dripped onto the anode substrate. A hole transport layer film is then formed by spin coating at a rotation speed of 2000 to 4000 rpm / min for 50 to 60 seconds. After the spin coating is completed, the film is annealed at 130 to 150° C. in an air environment for 15 to 20 minutes.

[0058] The perovskite precursor solution in step (3) is prepared by dissolving CsBr, PbBr2, and P123 (polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer) in N,N-dimethylformamide (DMF) or dimethyl sulfoxide (DMSO) in a mass ratio of 8.33:8.3:0.3. The perovskite precursor solution is spin-coated in a nitrogen environment in a glove box at a speed of 2000-4000 rpm / min for 50-60 seconds. After spin coating, heat treatment is continued in a nitrogen environment at a temperature of 50-80°C for 1-3 minutes.

[0059] The PEI (polyethyleneimine) organic solution in step (4) is PEI dissolved in isopropanol at a concentration of 0.2 mg / mL, wherein the molecular structure of PEI is as follows: Figure 2 The spin coating speed of PEI organic solution is 2000~5000rpm / min, and the spin coating time is 50~65s. After the spin coating is completed, vacuum treatment is carried out for 5~30min to make the pressure 1×10 - 1 mbar, and then let it stand in a vacuum environment for 0.5 to 1 hour.

[0060] The TPBi (1,3,5-tris(1-phenyl-1H-benzimidazol-2-yl)benzene) solution in step (5) is TPBi dissolved in DMF or DMSO, and the TPBi solution concentration is 3 to 5 mg / mL. The TPBi solution is spin-coated at a speed of 1000 to 3000 rpm / min for 50 to 60 seconds.

[0061] The vacuum-evaporated cathode modification layer in step (6) is LiF, and the thickness of the cathode modification layer is 0.3-1 nm. The vacuum-evaporated cathode is metallic silver or aluminum, and the thickness of the cathode is 80-150 nm.

[0062] Example 2

[0063] This embodiment provides a method for preparing a perovskite light-emitting diode using a low-pressure assisted solution method.

[0064] The structure of the perovskite light-emitting diode device provided in this embodiment is the same as that in Example 1, namely, anode (ITO) / hole transport layer (PEDOT:PSS:deionized water) / perovskite light-emitting layer / interface layer (PEI organic solution) / electron transport layer (TPBi) / / cathode modification layer (LiF) / cathode (Ag).

[0065] 1. Cleaning of anode ITO substrate

[0066] The ITO substrate was ultrasonically cleaned in deionized water, anhydrous ethanol, acetone, and isopropyl alcohol, sequentially for 20 minutes each time. After the ultrasonic cleaning, the ITO substrate was dried in an oven for at least 2 hours to ensure complete drying before use. The cleaned and dried ITO substrate was then treated with ultraviolet light for 5 minutes to ensure uniform distribution of the hole transport layer solution across the substrate.

[0067] 2. Preparation of Hole Transport Layer

[0068] (1) Preparation of hole transport layer solution: Take out the PEDOT:PSS solution from the 4°C refrigerator, let it stand for half an hour until the solution returns to room temperature, and then mix deionized water and the PEDOT:PSS aqueous solution in a volume ratio of 1:1 to obtain a hole transport layer solution.

[0069] (2) Preparation of hole transport layer: The hole transport layer solution was filtered through a 0.22 μm aqueous filter head and then dropped onto the ITO substrate. The solution was spin-coated at a speed of 3000 rpm / min for 60 s and then annealed in air at 130°C for 20 min. The thickness of the hole transport layer was 10 nm.

[0070] 3. Preparation of Perovskite Light-Emitting Layer

[0071] (1) Preparation of perovskite precursor solution: CsBr, PbBr2 and P123 reagents were mixed in a mass ratio of 83.3:8.3:0.3 and dissolved in DMSO to obtain a perovskite precursor solution.

[0072] (2) Preparation of perovskite light-emitting layer: According to Figure 1 The stacking order of the device structure shown is as follows: the ITO substrate coated with the hole transport layer is transferred into the glove box and spin-coated with the perovskite precursor solution. The spin-coating amount is 75 μL, the spin-coating speed is 2000 rpm / min, and the spin-coating time is 60 s. Then, a heat treatment process is performed at a temperature of 60 ° C for 1.5 minutes. The thickness of the perovskite light-emitting layer is 20 nm.

[0073] 4. Preparation of the Interface Layer

[0074] (1) Preparation of interface layer solution: PEI was dissolved in isopropanol to prepare a PEI organic solution with a concentration of 0.2 mg / mL.

[0075] (2) Preparation of the interface layer: After the perovskite light-emitting layer was prepared, the interface layer was treated in the glove box. The spin coating amount was 75 μL of isopropyl alcohol liquid, the spin coating speed was 4000 rpm / min, and the spin coating time was 60 s. Then, the existing device (i.e., anode / hole transport layer / perovskite light-emitting layer / interface layer) was placed in the small transition chamber of the glove box and vacuumed for 5 minutes to make the pressure 1×10 -1 mbar, and allowed to stand for 1 h to dry.

[0076] 5. Preparation of Electron Transport Layer

[0077] (1) Preparation of electron transport layer solution: The electron transport material TPBi was dissolved in DMSO to prepare a TPBi solution with a concentration of 5 mg / mL.

[0078] (2) Preparation of electron transport layer: After the interface layer is prepared, the device is transferred from the small transition chamber to the glove box to prepare the electron transport layer. The spin coating amount is 75 μL, the spin coating speed is 2000 rpm / min, and the spin coating time is 60 s.

[0079] 6. Preparation of cathode modification layer and cathode

[0080] After the electron transport layer is prepared, the device is transferred into a vacuum evaporation chamber for evaporation of the cathode modification layer (LiF) and the cathode (Ag). The thickness of the evaporated cathode modification layer is 1 nm, and the thickness of the evaporated cathode is 100 nm.

[0081] 7. Electrical performance characterization

[0082] After the silver electrode cathode evaporation is completed, the device is placed in a glove box for characterization of its electrical properties, namely the device's current, voltage, brightness, efficiency and other electrical properties.

[0083] Example 3

[0084] This embodiment provides a method for preparing a perovskite light-emitting diode using a low-pressure assisted solution method.

[0085] On the basis of Example 2, during the preparation of the interface layer, the existing device (i.e., anode / hole transport layer / perovskite light-emitting layer / interface layer) was placed in a small transition chamber of a glove box and vacuumed for 10 minutes to a pressure of 1×10 -1 mbar, and allowed to stand for 1 h to dry.

[0086] Example 4

[0087] This embodiment provides a method for preparing a perovskite light-emitting diode using a low-pressure assisted solution method.

[0088] On the basis of Example 2, during the preparation of the interface layer, the existing device (i.e., anode / hole transport layer / perovskite light-emitting layer / interface layer) was placed in a small transition chamber of a glove box and vacuumed for 20 minutes to a pressure of 1×10 -1 mbar, and allowed to stand for 1 h to dry.

[0089] Example 5

[0090] This embodiment provides a method for preparing a perovskite light-emitting diode using a low-pressure assisted solution method.

[0091] On the basis of Example 2, during the preparation of the interface layer, the existing device (i.e., anode / hole transport layer / perovskite light-emitting layer / interface layer) was placed in a small transition chamber of a glove box and vacuumed for 30 minutes to a pressure of 1×10 -1mbar, and allowed to stand for 1 h to dry.

[0092] Example 6

[0093] This embodiment provides a method for preparing a perovskite light-emitting diode using a low-pressure assisted solution method.

[0094] The structure of the perovskite light-emitting diode device provided in this embodiment is the same as that in Example 1.

[0095] 1. Cleaning of the anode FTO substrate

[0096] The FTO substrate was ultrasonically cleaned in deionized water, anhydrous ethanol, acetone, and isopropanol, sequentially for 30 minutes each time. After the ultrasonic cleaning, the FTO substrate was dried in an oven for at least 2 hours to ensure complete drying before use. The cleaned and dried FTO substrate was then subjected to a plasma bombardment treatment for 5 minutes to ensure uniform distribution of the hole transport layer solution across the FTO substrate.

[0097] 2. Preparation of Hole Transport Layer

[0098] (1) Preparation of hole transport layer solution: Take out the PEDOT:PSS solution from the 4°C refrigerator, let it stand for half an hour until the solution returns to room temperature, and then mix deionized water and the PEDOT:PSS aqueous solution in a volume ratio of 1:1 to obtain a hole transport layer solution.

[0099] (2) Preparation of hole transport layer: The hole transport layer solution was filtered through a 0.22 μm aqueous filter head and then dropped onto the FTO substrate. The solution was spin-coated at a speed of 2000 rpm / min for 50 s and then annealed in air at 150°C for 15 min.

[0100] 3. Preparation of Perovskite Light-Emitting Layer

[0101] (1) Preparation of perovskite precursor solution: CsBr, PbBr2 and P123 reagents were mixed in a mass ratio of 83.3:8.3:0.3 and dissolved in DMF to obtain a perovskite precursor solution.

[0102] (2) Preparation of perovskite light-emitting layer: According to Figure 1 The stacking order of the device structure shown is as follows: the FTO substrate coated with the hole transport layer is transferred into the glove box and the perovskite precursor solution is spin-coated with a spin coating amount of 75 μL, a spin coating speed of 4000 rpm / min, and a spin coating time of 50 s. Then, a heat treatment process is performed at a temperature of 50°C and heating for 1 min.

[0103] 4. Preparation of the Interface Layer

[0104] (1) Preparation of interface layer solution: PEI was dissolved in isopropanol to prepare a PEI organic solution with a concentration of 0.2 mg / mL.

[0105] (2) Preparation of interface layer: After the perovskite light-emitting layer was prepared, the interface layer was treated in the glove box. The amount of PEI organic solution used for spin coating was 75 μL, the spin coating speed was 2000 rpm / min, and the spin coating time was 50 s. Then, the existing device (i.e., anode / hole transport layer / perovskite light-emitting layer / interface layer) was placed in the small transition chamber of the glove box and vacuumed for 30 minutes to make the pressure 1×10 -1 mbar, and allowed to stand for 0.5 h to dry.

[0106] 5. Preparation of Electron Transport Layer

[0107] (1) Preparation of electron transport layer solution: The electron transport material TPBi was dissolved in DMF to prepare a TPBi solution with a concentration of 3 mg / mL.

[0108] (2) Preparation of electron transport layer: After the interface layer is prepared, the device is transferred from the small transition chamber to the glove box to prepare the electron transport layer. The spin coating amount is 75 μL, the spin coating speed is 1000 rpm / min, and the spin coating time is 50 s.

[0109] 6. Preparation of cathode modification layer and cathode

[0110] After the electron transport layer is prepared, the device is transferred into a vacuum evaporation chamber for evaporation of the cathode modification layer (LiF) and the cathode (Al). The thickness of the evaporated cathode modification layer is 0.3 nm, and the thickness of the evaporated cathode is 80 nm.

[0111] The perovskite light-emitting diode prepared in this embodiment has an external quantum efficiency of 2.1% and a brightness of 3670 cd / m 2 .

[0112] Example 7

[0113] This embodiment provides a method for preparing a perovskite light-emitting diode using a low-pressure assisted solution method.

[0114] The structure of the perovskite light-emitting diode device provided in this embodiment is the same as that in Example 1.

[0115] 1. Cleaning of anode ITO substrate

[0116] The ITO substrate was ultrasonically cleaned in deionized water, anhydrous ethanol, acetone, and isopropyl alcohol, sequentially for 30 minutes each time. After the ultrasonic cleaning, the ITO substrate was dried in an oven for at least 2 hours to ensure complete drying before use. The cleaned and dried ITO substrate was then treated with ultraviolet light for 5 minutes to ensure uniform distribution of the hole transport layer solution across the substrate.

[0117] 2. Preparation of Hole Transport Layer

[0118] (1) Preparation of hole transport layer solution: Take out the PEDOT:PSS solution from the 4°C refrigerator, let it stand for half an hour until the solution returns to room temperature, and then mix deionized water and the PEDOT:PSS aqueous solution in a volume ratio of 1:1 to obtain a hole transport layer solution.

[0119] (2) Preparation of hole transport layer: The hole transport layer solution was filtered through a 0.22 μm aqueous filter head and then dropped onto the ITO substrate. The spin coating process was performed at a speed of 4000 rpm / min for 50 s, and then annealed in air at 150°C for 15 min.

[0120] 3. Preparation of Perovskite Light-Emitting Layer

[0121] (1) Preparation of perovskite precursor solution: CsBr, PbBr2 and P123 reagents were mixed in a mass ratio of 83.3:8.3:0.3 and dissolved in DMSO to obtain a perovskite precursor solution.

[0122] (2) Preparation of perovskite light-emitting layer: According to Figure 1 The stacking order of the device structure shown is as follows: the ITO substrate coated with the hole transport layer is transferred into the glove box and the perovskite precursor solution is spin-coated with a spin coating amount of 75 μL, a spin coating speed of 4000 rpm / min, and a spin coating time of 50 s. Then, a heat treatment process is performed at a temperature of 80°C and heating for 3 minutes.

[0123] 4. Preparation of the Interface Layer

[0124] (1) Preparation of interface layer solution: PEI was dissolved in isopropanol to prepare a PEI organic solution with a concentration of 0.2 mg / mL.

[0125] (2) Preparation of the interface layer: After the perovskite light-emitting layer was prepared, the interface layer was treated in the glove box. The spin coating amount was 75 μL of PEI organic solution, the spin coating speed was 5000 rpm / min, and the spin coating time was 50 s. Then, the existing device (i.e., anode / hole transport layer / perovskite light-emitting layer / interface layer) was placed in the small transition chamber of the glove box and vacuumed for 30 minutes to make the pressure 1×10 -1 mbar, and allowed to stand for 0.5 h to dry.

[0126] 5. Preparation of Electron Transport Layer

[0127] (1) Preparation of electron transport layer solution: The electron transport material TPBi was dissolved in DMSO to prepare a TPBi solution with a concentration of 3 mg / mL.

[0128] (2) Preparation of electron transport layer: After the interface layer is prepared, the device is transferred from the small transition chamber to the glove box to prepare the electron transport layer. The spin coating amount is 75 μL, the spin coating speed is 3000 rpm / min, and the spin coating time is 50 s.

[0129] 6. Preparation of cathode modification layer and cathode

[0130] After the electron transport layer is prepared, the device is transferred into a vacuum evaporation chamber for evaporation of the cathode modification layer (LiF) and the cathode (Ag). The thickness of the evaporated cathode modification layer is 0.3 nm, and the thickness of the evaporated cathode is 150 nm.

[0131] The perovskite light-emitting diode prepared in this embodiment has an external quantum efficiency of 2.2% and a brightness of 3885 cd / m 2 .

[0132] Example 8

[0133] This example provides the electrical performance of perovskite light-emitting diodes prepared by a low-voltage assisted solution method.

[0134] The present invention tests the electrical properties of the perovskite light-emitting diodes prepared in Examples 2 to 5, such as current density, voltage, current efficiency, and brightness, to obtain corresponding curves.

[0135] The current density-voltage curve is as follows Figure 3 As shown in the figure, with the increase of low-pressure pumping time of the interface layer PEI organic solution, the current density shows an upward trend. This is because PEI evaporates more and has a lower concentration. The interface layer plays a good role in suppressing interface loss and improving energy relations, promoting the effective recombination of carriers, and changing the electrical properties of the diode device.

[0136] Brightness-voltage curve Figure 4 As shown in the figure, the device brightness increases significantly with increasing the time of low-pressure pumping of the PEI organic solution in the interface layer. During this process, the concentration of the interface layer solution first changes the thickness and density of the PEI in the interface layer. When the concentration of the PEI organic solution is low, the interface layer effectively suppresses interface losses and improves energy relations, promoting effective carrier recombination and significantly improving the device brightness.

[0137] The embodiments described above are some of the embodiments of the present invention, rather than all of them. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments obtained without creative effort and through deduction and substitution by a person of ordinary skill in the art based on the concept of the present invention are within the scope of protection of the present invention.

Claims

1. A method for preparing a perovskite light-emitting diode by a low-pressure assisted solution method, characterized in that: include: providing an interface layer between the perovskite light-emitting layer and the electron transport layer of the perovskite light-emitting diode; The polyethyleneimine organic solution was spin-coated on the perovskite light-emitting layer, so that the gas pressure was reduced to 1×10 -1 mbar or less, maintain the air pressure, and let it stand and dry to obtain the interface layer; Dissolving polyethyleneimine in isopropyl alcohol to obtain the polyethyleneimine organic solution, wherein the concentration of the polyethyleneimine organic solution is 0.2 mg / mL; The spin coating speed is 2000-5000 rpm / min, and the spin coating time is 50-60 s; The time for standing and drying is 0.5 to 1 hour.

2. The method according to claim 1, characterized in that include: The hole transport layer, the perovskite light emitting layer, the interface layer and the electron transport layer are prepared by spin coating on the anode substrate in sequence by a solution method; Then, a cathode modification layer and a cathode are sequentially vacuum-evaporated on the electron transport layer.

3. The method according to claim 2, characterized in that The anode substrate is sequentially ultrasonically cleaned with deionized water, anhydrous ethanol, acetone, and isopropanol for at least 20 to 30 minutes each; Then, the anode substrate is subjected to surface treatment; The surface treatment is any one of plasma bombardment surface treatment and ultraviolet light treatment.

4. The method according to claim 2, characterized in that The hole transport layer is prepared by spin coating PEDOT:PSS and then annealing; The PEDOT:PSS solution was ultrasonically mixed with water in a volume ratio of 1:1 for 2 hours. The spin coating speed is 2000-4000 rpm / min, and the spin coating time is 50-60 s; The annealing temperature is 130-150° C., the annealing time is 15-20 min, and the annealing environment is air.

5. The method according to claim 2, characterized in that The perovskite light-emitting layer is prepared by spin coating a perovskite precursor solution and then heat treating it; The perovskite precursor solution is prepared by dissolving CsBr, PbBr2 and P123 in DMF or DMSO; The spin coating speed is 2000-4000 rpm / min, the spin coating time is 50-60 s, and the spin coating environment is nitrogen; The heat treatment temperature is 50-80°C, the heat treatment time is 1-3 minutes, and the heat treatment environment is nitrogen; The mass ratio of the CsBr, PbBr2 and P123 is 8.33:8.3:0.

3.

6. The method according to claim 2, characterized in that The electron transport layer is prepared by spin coating of TPBi solution; The TPBi solution is TPBi dissolved in DMF or DMSO, and the concentration of the TPBi solution is 3-5 mg / mL; The spin coating speed is 1000-3000 rpm / min, and the spin coating time is 50-65 s.

7. The method according to claim 2, characterized in that The cathode modification layer is LiF, and the thickness of the cathode modification layer is 0.3-1 nm; The cathode is made of any one of metal silver and aluminum, and the thickness of the cathode is 80-150 nm.

8. A perovskite light-emitting diode, characterized in that: Prepared by the method according to any one of claims 1 to 7.

9. The perovskite light-emitting diode according to claim 8, characterized in that The invention comprises a hole transport layer, a perovskite light-emitting layer, an interface layer, an electron transport layer, a cathode modification layer and a cathode which are sequentially arranged on an anode substrate.

Images