3D perovskite light-emitting diode and preparation method thereof

Abstract

The present invention provides a 3D perovskite light-emitting diode and a preparation method thereof. The 3D perovskite light-emitting diode comprises a patterned transparent anode layer, an anode interface layer, a perovskite light-emitting layer, a cathode interface layer, a cathode interface modification layer, and a cathode layer, which are sequentially prepared on a substrate. The perovskite light-emitting layer is doped with an ionic compound containing an imino group. The ionic compound containing an imino group acts as an organic spacer to induce the formation of 2D grains within the perovskite light-emitting layer that are close to the size of 3D grains. The present invention uses the ionic compound containing an imino group as an organic spacer to induce the formation of 2D large n-phase grains within the perovskite light-emitting layer, which self-assemble to form a perovskite light-emitting layer with a 2D / 3D mixed phase distribution. The tight embedding of the 2D grains effectively improves the optical properties of the perovskite light-emitting layer, optimizes the surface morphology of the perovskite light-emitting layer, and utilizes the 2D / 3D heterophase perovskite structure to effectively suppress PL broadening and multi-peak emission phenomena, thereby improving the performance and stability of the light-emitting device.

Description

Technical Field

[0001] The present invention relates to the technical field of light-emitting diodes, and in particular to a 3D perovskite light-emitting diode and a preparation method thereof. Background Art

[0002] Metal lead halide perovskites, as a popular semiconductor material, have attracted great scientific interest in optoelectronics, such as photovoltaic cells, light-emitting diodes (LEDs), lasers, and detectors. Their outstanding optical and electrical properties, such as high photoluminescence quantum efficiency (PLQY), tunable band gap, high carrier mobility, and high color purity, as well as their solution processability, hold great promise for application in cost-effective, high-performance optoelectronic devices. Since the first report of perovskite light-emitting diodes (PeLEDs) operating at room temperature by Richard H. Friend and Zhi-Kuang Tan in 2014 (Nat. Nanotechnol. 2014, 9, 687), research has been underway. After just 7 years of development, the external quantum efficiency (EQE) has increased from less than 0.1% to more than 20%. (Nature 2018, 562, 245; Nature 2018, 591, 72; Nat. Photonics 2018, 12, 783) Perovskite-type light-emitting diodes (PeLEDs) have become an important field of scientific research. In particular, the development of organic-inorganic hybrid perovskite systems and low-dimensional perovskite structure PeLEDs has achieved an external quantum efficiency EQE of more than 20%. However, whether it is a small organic methyl ammonium cationic + ) or formamidine (FA + ), or the large organic cation phenylethylammonium (PEA + ), benzyl ammonium (PA + ) occupying the A site of the perovskite lattice will increase the sensitivity of the light-emitting layer to water, electrical stress, and heat, seriously affecting the stability of PeLEDs. However, the all-inorganic cesium cation perovskite component, namely CsPbX3 (X = Cl, Br, and I), exhibits better thermal and chemical stability than its mixed analogs. Therefore, by improving the optoelectronic performance of all-inorganic PeLEDs, it may provide a significant boost to the further research and development of PeLEDs.

[0003] However, Cs-based all-inorganic perovskites have severe defect states and high non-radiative recombination, which limits the brightness and current efficiency of the resulting PeLEDs. This is primarily due to uneven grain growth, poor crystallization quality, and numerous defects at grain boundaries. Over the past few years, various strategies have been proposed to achieve high-quality, high-coverage, and low-defect-density CsPbBr3 light-emitting layers via solution spin coating, including antisolvent vapor treatment, passivation agent addition, precursor composition optimization, and interface-induced crystal growth. Sun Baoquan's group at Soochow University used Na ions to replace commonly used organic long-chain spacer cations, constructing two-dimensional-three-dimensional (2D-3D) perovskites with inorganic ions, resulting in dense and uniform cesium-based perovskite films. They achieved green PeLEDs with excellent operational stability and an EQE as high as 15.9%. (ACS Nano 2019, 13, 1645) Zeng Haibo's group at Nanjing University of Science and Technology used methylenebisacrylamide and potassium persulfate to form a cross-linked passivation system to achieve defect passivation and inhibit ion migration. This passivation strategy not only yielded a green PeLED with an EQE of 16.8%, but also achieved a high-performance green PeLED at an initial luminance of 100 cd m -2 Under the conditions of 100 nm, the device half-life (T50) reached 208 hours, achieving efficient and stable perovskite PeLED. (Advanced Functional Materials 2021, 31, 26) It is precisely because of this rapid development of PeLEDs that we foresee its broad application prospects in the future display field.

[0004] Although the performance of PeLEDs has been greatly improved in just a few years, compared with the commercialized organic light-emitting diodes and inorganic quantum dot light-emitting diodes (EQE: more than 25%), there is still a lot of room for improvement in their luminous efficiency and stability. At present, the main method to improve the luminous efficiency of PeLEDs is to regulate the morphology of the light-emitting layer and suppress defects. Because perovskite materials have very good crystallization properties, larger grains are easily formed during the film formation process, resulting in poor coverage of thinner light-emitting layers, which in turn increases the defect density at the grain boundaries, thereby affecting the luminous performance of the device. This discontinuous light-emitting layer will also lead to an increase in device leakage current or increase the risk of device short circuit. Therefore, obtaining a uniform, dense perovskite light-emitting layer with high fluorescence quantum efficiency is crucial to achieving high-efficiency PeLEDs. Summary of the Invention

[0005] In order to solve the technical problems in the prior art of low luminous efficiency of 3D perovskite light-emitting diodes, such as excessive surface grain growth of the inorganic perovskite light-emitting layer and high defect density within the film, the present invention proposes a 3D perovskite light-emitting diode and a preparation method thereof, which can improve the luminous performance and stability of the 3D perovskite light-emitting diode.

[0006] To achieve the above objectives, the present invention adopts the following specific technical solutions:

[0007] The 3D perovskite light-emitting diode provided by the present invention includes a patterned transparent anode layer, an anode interface layer, a perovskite light-emitting layer, a cathode interface layer, a cathode interface modification layer and a cathode layer, which are sequentially prepared on a substrate. The perovskite light-emitting layer is doped with an ionic compound containing an imino group. The ionic compound containing an imino group acts as an organic spacer to induce the formation of 2D grains with a size close to that of 3D grains inside the perovskite light-emitting layer, so that the perovskite light-emitting layer has a 2D / 3D heterophase perovskite structure.

[0008] Preferably, the imino group-containing ionic compound is diethylamine hydrobromide, methylethylamine hydrobromide, dipropylamine hydrobromide, diisopropylamine hydrobromide or dibutylamine hydrobromide.

[0009] Preferably, the perovskite light-emitting layer is any one of inorganic perovskites CsPbBr3, CsPbCl3 or CsPbI3, or a combination of two or more thereof.

[0010] Preferably, the patterned transparent anode layer is an indium tin oxide electrode with a thickness of 50-200 nm.

[0011] Preferably, the anode interface layer is PEDOT:PSS with a thickness of 10-50 nm.

[0012] Preferably, the cathode interface layer is TPBi with a thickness of 5-50 nm.

[0013] Preferably, the cathode interface modification layer is lithium fluoride with a thickness of 0.5-3 nm.

[0014] Preferably, the cathode layer is aluminum or silver, with a thickness of 20-150 nm.

[0015] The method for preparing a 3D perovskite light-emitting diode provided by the present invention comprises the following steps:

[0016] S1, preparing a patterned transparent anode layer on a substrate;

[0017] S2, preparing an anode interface layer on the patterned transparent anode layer;

[0018] S3, growing a perovskite light-emitting layer on the anode interface layer;

[0019] S4. A cathode interface layer, a cathode interface modification layer, and a cathode layer are sequentially prepared on the perovskite light-emitting layer by evaporation. When growing the perovskite light-emitting layer, an ionic compound containing an imine group is added to the perovskite precursor solution. The ionic compound containing an imine group acts as an organic spacer to induce the formation of 2D grains close to the 3D grain size inside the perovskite light-emitting layer, so that the perovskite light-emitting layer becomes a 2D / 3D heterophase perovskite structure.

[0020] Preferably, the preparation method of the perovskite precursor solution is as follows: using DMSO as the solvent, any one or a combination of two or more of the inorganic perovskites CsPbBr3, CsPbCl3 or CsPbI3 as the solute, adding an ionic compound containing an imine group at a concentration of 1 mg / mL-40 mg / mL to the solute, and fully stirring the solvent and solute at 20°C-80°C to form a perovskite precursor solution.

[0021] Preferably, step S2 specifically includes the following steps:

[0022] S21, placing the cleaned substrate with a patterned transparent anode layer having a thickness of 50-200 nm on a bracket of a spin coater;

[0023] S22, adjusting the rotation speed of the spin coater to 1000-5000 r / min, so that the PEDOT:PSS solution is evenly coated on the patterned transparent anode layer and forms an anode interface layer on the surface of the patterned transparent anode layer;

[0024] Step S3 specifically includes the following steps:

[0025] S31, preparing a perovskite precursor solution, and adding an ionic compound containing an imine group to the perovskite precursor solution;

[0026] S32, evenly spin-coating the perovskite precursor solution on the surface of the anode interface layer, controlling the spin-coating speed to be 1000-5000 r / min;

[0027] S33, placing the substrate on which the perovskite precursor solution is spin-coated on a hot stage for annealing to form a perovskite light-emitting layer, forming 2D grains close to the size of the 3D grains in the perovskite light-emitting layer, and the 2D grains and the 3D grains are mixed and distributed in the perovskite light-emitting layer;

[0028] Step S4 specifically includes the following steps:

[0029] The substrate with the perovskite light-emitting layer was placed in a vacuum coating machine for vacuum treatment. When the vacuum degree reached 4×10 -4 Pa, a cathode interface layer, a cathode interface modification layer and a cathode layer are sequentially evaporated on the surface of the perovskite light-emitting layer.

[0030] The present invention uses an ionic compound containing an imino group as an organic spacer to induce the formation of 2D large n-phase grains with a size close to that of 3D crystals in the perovskite light-emitting layer, and self-assembles to form a perovskite light-emitting layer with a 2D / 3D mixed phase distribution. The tight embedding of the 2D grains effectively improves the optical properties of the perovskite light-emitting layer, optimizes the surface morphology of the perovskite light-emitting layer, and utilizes the 2D / 3D heterogeneous perovskite structure to effectively suppress the PL broadening and multi-peak emission phenomena, thereby improving the performance and stability of the light-emitting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 2. It is a schematic structural diagram of a 3D perovskite light-emitting diode provided by the present invention;

[0032] Figure 2 2D / 3D heterophase structure diagram of the perovskite light-emitting layer provided by the present invention;

[0033] Figure 3 3D perovskite light-emitting diode according to the present invention;

[0034] Figure 4a and Figure 4b Schematic diagrams of electron microscope scanning of the perovskite light-emitting layer in Comparative Example 1 and Example 1 provided according to the present invention;

[0035] Figure 5 Schematic diagram of the photoluminescence spectra of the perovskite light-emitting layer in Comparative Example 1 (curve 1) and Example 1 (curve 2) provided by the present invention;

[0036] Figure 6 1 is a schematic diagram of the electroluminescence spectrum (curve 1) and the photoluminescence spectrum (curve 2) of the perovskite light-emitting layer in Example 1 provided by the present invention;

[0037] Figure 7a and Figure 7b Schematic diagrams of the performance of the 3D perovskite light-emitting diodes in Comparative Example 1 (curve 1) and Example 1 (curve 2) provided by the present invention;

[0038] Figure 8 1 is a schematic diagram comparing the performance of the 3D perovskite light-emitting diodes in Comparative Example 1 (curve 1) and Example 1 (curve 2) provided according to the present invention.

[0039] The reference numerals include: substrate 1 , patterned transparent anode layer 2 , anode interface layer 3 , perovskite light-emitting layer 4 , cathode interface layer 5 , cathode interface modification layer 6 , cathode layer 7 . DETAILED DESCRIPTION

[0040] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, identical modules are denoted by identical reference numerals. In the case of identical reference numerals, their names and functions are also identical. Therefore, their detailed description will not be repeated.

[0041] Figure 1 The structure of the 3D perovskite light-emitting diode provided according to the present invention is shown.

[0042] like Figure 1 As shown, the 3D perovskite light-emitting diode provided by the present invention includes a substrate 1, on which a patterned transparent anode layer 2, an anode interface layer 3, a perovskite light-emitting layer 4, a cathode interface layer 5, a cathode interface modification layer 6 and a cathode layer 7 are sequentially stacked. The perovskite light-emitting layer 4 is doped with an ionic compound containing an imino group, and the imino cation is used as an organic spacer cation. Its appropriate coordination ability can effectively avoid the distribution of the low n phase and promote the formation of the large n phase, that is, induce the perovskite light-emitting layer 4 to form quasi-two-dimensional large n-phase grains with a size close to that of the 3D grains inside the perovskite light-emitting layer 4, and the 2D grains of the large n-phase grains form a 2D / 3D heterophase perovskite structure with the 3D grains in the perovskite light-emitting layer 4, as shown in FIG. Figure 2 shown.

[0043] The imino group-containing ionic compound is any one of diethylamine hydrobromide, methylethylamine hydrobromide, dipropylamine hydrobromide, diisopropylamine hydrobromide and dibutylamine hydrobromide.

[0044] The perovskite light-emitting layer 4 is any one or more of inorganic perovskites CsPbBr3, CsPbCl3 or CsPbI3 doped with an ionic compound containing an imine group.

[0045] The substrate 1 is made of transparent materials such as glass and quartz, and has a thickness of 1-5 mm.

[0046] The patterned transparent anode layer 2 is an indium tin oxide electrode with a thickness of 50-200 nm.

[0047] The anode interface layer 3 is PEDOT:PSS with a thickness of 10-50 nm.

[0048] The cathode interface layer 5 is TPBi with a thickness of 5-50 nm.

[0049] The cathode interface modification layer 6 is lithium fluoride with a thickness of 0.5-3 nm.

[0050] The cathode layer 7 is made of aluminum or silver, and has a thickness of 20-150 nm.

[0051] Figure 3 The flowchart of the method for preparing a 3D perovskite light-emitting diode provided by the present invention is shown.

[0052] like Figure 3 As shown, the preparation method of the 3D perovskite light-emitting diode provided by the present invention comprises the following steps:

[0053] S1, preparing a patterned transparent anode layer on a substrate;

[0054] S2, preparing an anode interface layer on the patterned transparent anode layer;

[0055] S3, growing a perovskite light-emitting layer on the anode interface layer;

[0056] S4. A cathode interface layer, a cathode interface modification layer, and a cathode layer are sequentially prepared on the perovskite light-emitting layer by evaporation. When growing the perovskite light-emitting layer, an ionic compound containing an imine group is added to the perovskite precursor solution. The ionic compound containing an imine group acts as an organic spacer to induce the formation of 2D grains close to the 3D grain size inside the perovskite light-emitting layer, so that the perovskite light-emitting layer becomes a 2D / 3D heterophase perovskite structure.

[0057] Specifically:

[0058] Step 1: Place the cleaned substrate 1 with a 50-200 nm thick patterned transparent anode layer 2 on the bracket of a spin coater, and evenly coat the entire patterned transparent anode layer 2 with PEDOT:PSS through a 0.45 μm filter head. Adjust the rotation speed of the spin coater to 1000-5000 r / min so that PEDOT:PSS forms a 10-50 nm thick anode interface layer 3 on the surface of the patterned transparent anode layer, and heat it in a 120°C oven for 30 minutes.

[0059] Step 2: Transfer the above substrate to a glove box and place the substrate on the bracket of a spin coater. Evenly drop the prepared perovskite precursor solution on the above substrate 1. Adjust the speed of the spin coater to 1000-5000 r / min. After spin coating for 1 minute, a 20-200 nm thick perovskite light-emitting layer 4 is obtained.

[0060] The preparation method of the above-mentioned perovskite precursor solution is as follows: using dimethyl sulfoxide (DMSO) as a solvent and one or more of the inorganic perovskites CsPbBr3, CsPbCl3 or CsPbI3 as a solute, adding an ionic compound containing an imine group at a concentration of 1 mg / mL-40 mg / mL to the solute, and fully stirring at 20°C-80°C to form a perovskite precursor solution.

[0061] Step 3: Place the product obtained in step 2 into a vacuum coating machine and evacuate the vacuum. -4Pa, a cathode interface layer 5 with a thickness of 5-50 nm, a cathode interface modification layer 6 with a thickness of 0.5-3 nm, and a cathode layer 7 with a thickness of 20-150 nm are evaporated in sequence.

[0062] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0063] Example 1

[0064] The method for preparing a 3D perovskite light-emitting diode provided in this embodiment 1 includes the following steps:

[0065] Step 1. Place a cleaned 1 mm thick glass substrate (with a 120 nm thick patterned transparent anode layer) on the bracket of a spin coater, and evenly coat the patterned transparent anode layer with PEDOT:PSS through a 0.45 μm filter head. Adjust the rotation speed of the spin coater to 2500 r / min to form a 30 nm thick anode interface layer of PEDOT:PSS on the surface of the patterned transparent anode layer, and heat it in a 120°C oven for 30 minutes.

[0066] Step 2: Transfer the above substrate to a glove box and place the substrate on the bracket of a spin coater. Evenly drop the mixed perovskite precursor solution on the anode interface layer. Adjust the speed of the spin coater to 2500 r / min. After spin coating for 1 minute, a 30 nm thick perovskite light-emitting layer is obtained.

[0067] The perovskite precursor solution was prepared as follows: dimethyl sulfoxide was used as solvent, inorganic perovskite CsPbBr3 was used as solute, and the concentration of diethylamine hydrobromide was 13 mg / mL. The solution was heated and stirred at 60° C. for 3 hours, and then the heating was stopped and the solution was stirred for 12 hours.

[0068] Step 3: Place the product obtained in step 2 into a vacuum coating machine and evacuate the vacuum. -4 Pa, a 20 nm thick TPBi cathode interface layer, a 1 nm thick LiF cathode interface modification layer, and a 100 nm thick Al cathode layer were evaporated in sequence.

[0069] Example 2

[0070] The method for preparing a 3D perovskite light-emitting diode provided in this embodiment 2 includes the following steps:

[0071] Step 1. Place a cleaned 2 mm thick glass substrate (with a 50 nm thick patterned transparent anode layer) on the bracket of a spin coater, and evenly coat the patterned transparent anode layer with PEDOT:PSS through a 0.45 μm filter head. Adjust the rotation speed of the spin coater to 1000 r / min to form a 50 nm thick anode interface layer of PEDOT:PSS on the surface of the patterned transparent anode layer, and heat it in a 120°C oven for 30 minutes.

[0072] Step 2: Transfer the substrate to a glove box and place it on the bracket of a spin coater. Evenly drip the mixed perovskite precursor solution onto the anode interface layer. Adjust the spin coater speed to 5000 rpm. After 1 minute of spin coating, a 20 nm thick perovskite light-emitting layer is obtained. The perovskite precursor solution is prepared as follows: using dimethyl sulfoxide as the solvent, the inorganic perovskite CsPbCl3 as the solute, and methylethylamine hydrobromide at a concentration of 1 mg / mL. Heat and stir at 60°C for 3 hours, stop heating, and continue stirring for 12 hours.

[0073] Step 3: Place the product obtained in step 2 into a vacuum coating machine and evacuate the vacuum. -4 Pa, a 50 nm thick TPBi cathode interface layer, a 2 nm thick LiF cathode interface modification layer, and a 20 nm thick Ag cathode layer were evaporated in sequence.

[0074] Example 3

[0075] The method for preparing a 3D perovskite light-emitting diode provided in this embodiment 3 includes the following steps:

[0076] Step 1. Place a clean 5 mm thick quartz substrate (with a 200 nm thick patterned transparent anode layer) on the bracket of a spin coater. Use a 0.45 μm filter to evenly coat the patterned transparent anode layer with PEDOT:PSS. Adjust the rotation speed of the spin coater to 5000 rpm to form a 10 nm thick anode interface layer of PEDOT:PSS on the surface of the patterned transparent anode layer. Place the substrate in an oven at 120°C and heat for 30 minutes.

[0077] Step 2: Transfer the above substrate to a glove box and place the substrate on the bracket of a spin coater. Evenly drop the mixed perovskite precursor solution on the anode interface layer. Adjust the speed of the spin coater to 1000 r / min. After spin coating for 1 minute, a 200 nm thick perovskite light-emitting layer is obtained.

[0078] The perovskite precursor solution was prepared as follows: dimethyl sulfoxide was used as solvent, inorganic perovskite CsPbI3 was used as solute, and the concentration of dipropylamine hydrobromide was 40 mg / mL. The solution was heated and stirred at 40° C. for 3 hours, and then the heating was stopped and the solution was stirred for 12 hours.

[0079] Step 3: Place the product obtained in step 2 into a vacuum coating machine and evacuate the vacuum. -4 Pa, a 5 nm thick TPBi cathode interface layer, a 0.5 nm thick LiF cathode interface modification layer, and an 80 nm thick Al cathode layer were evaporated in sequence.

[0080] Example 4

[0081] The method for preparing a 3D perovskite light-emitting diode provided in this embodiment 4 includes the following steps:

[0082] Step 1: Place a cleaned 2 mm thick quartz substrate (with a 50 nm thick patterned transparent anode layer) on the bracket of a spin coater. Pass a 0.45 μm filter head to evenly coat the patterned transparent anode layer with PEDOT:PSS. Adjust the rotation speed of the spin coater to 1000 rpm to form a 50 nm thick anode interface layer of PEDOT:PSS on the surface of the patterned transparent anode layer. Heat the substrate in a 120°C oven for 30 minutes.

[0083] Step 2: Transfer the above substrate to a glove box and place the substrate on the bracket of a spin coater. Evenly drip the mixed perovskite precursor solution on the anode interface layer. Adjust the speed of the spin coater to 5000 r / min. After spinning for 1 minute, a 50 nm thick perovskite light-emitting layer is obtained. The preparation method of the above perovskite precursor solution is as follows: dimethyl sulfoxide is used as the solvent, inorganic perovskites CsPbBr3 and CsPbCl3 are used as solutes, and the concentration of diisopropylamine hydrobromide is 1 mg / mL-40 mg / mL. Heat and stir at 40°C for 3 hours, stop heating, and continue stirring for 12 hours.

[0084] Step 3: Place the product obtained in step 2 into a vacuum coating machine and evacuate the vacuum. -4 At 1.5 Pa, a 50 nm thick TPBi cathode interface layer, a 3 nm thick LiF cathode interface modification layer and a 150 nm thick Ag cathode layer were evaporated in sequence.

[0085] Example 5

[0086] The method for preparing a 3D perovskite light-emitting diode provided in this embodiment 5 includes the following steps:

[0087] Step 1. Place a clean 2 mm thick quartz substrate (with a 50 nm thick patterned transparent anode layer) on the bracket of a spin coater, and evenly coat the patterned transparent anode layer with PEDOT:PSS through a 0.45 μm filter head. Adjust the rotation speed of the spin coater to 1000 r / min to form a 50 nm thick anode interface layer of PEDOT:PSS (polythiophene derivative poly (3,4-ethylenedioxythiophene) doped polystyrene sulfonic acid) on the surface of the patterned transparent anode layer, and heat it in a 120°C oven for 30 minutes.

[0088] Step 2: Transfer the above substrate to a glove box and place the substrate on the bracket of a spin coater. Evenly drop the mixed perovskite precursor solution on the anode interface layer. Adjust the speed of the spin coater to 5000 r / min. After spin coating for 1 minute, a 50 nm thick perovskite light-emitting layer is obtained.

[0089] The perovskite precursor solution was prepared by using dimethyl sulfoxide as solvent, inorganic perovskites CsPbBr3, CsPbCl3 and CsPbI3 as solutes, and a dibutylamine hydrobromide concentration of 40 mg / mL. The solution was heated and stirred at 40 degrees for 3 hours, and then the heating was stopped and the stirring was continued for 12 hours.

[0090] Step 3: Place the product obtained in step 2 into a vacuum coating machine and evacuate the vacuum. -4 At 1.5 Pa, a 50 nm thick TPBi cathode interface layer, a 3 nm thick LiF cathode interface modification layer and a 150 nm thick Ag cathode layer were evaporated in sequence.

[0091] Comparative Example 1

[0092] The preparation method of the 3D perovskite light-emitting diode provided in this comparative example 1 comprises the following steps:

[0093] Step 1: Place a cleaned 1 mm thick glass substrate (with a 120 nm thick patterned transparent anode layer) on the bracket of a spin coater. Pass a 0.45 μm filter head to evenly coat the patterned transparent anode layer with PEDOT:PSS. Adjust the rotation speed of the spin coater to 2500 rpm to form a 30 nm thick anode interface layer of PEDOT:PSS on the surface of the transparent electrode. Heat it in a 120°C oven for 30 minutes.

[0094] Step 2: Transfer the above substrate to a glove box and place the substrate on the bracket of a spin coater. Evenly drop the mixed perovskite precursor solution on the anode interface layer. Adjust the spin coater speed to 2500 r / min. After spin coating for 1 minute, a 30 nm thick perovskite light-emitting layer is obtained.

[0095] The perovskite precursor solution was prepared as follows: dimethyl sulfoxide was used as solvent, inorganic perovskite CsPbBr3 was used as solute, the solution concentration was 20%, and the solution was heated and stirred at 60° C. for 3 hours, and then the heating was stopped and the stirring was continued for 12 hours.

[0096] Step 3: Place the product obtained in step 2 into a vacuum coating machine and evacuate the vacuum. -4 Pa, a 20 nm thick TPBi cathode interface layer, a 1 nm thick LiF cathode interface modification layer, and a 100 nm thick Al cathode layer were evaporated in sequence.

[0097] Comparative Example 2

[0098] The preparation method of the 3D perovskite light-emitting diode provided in this comparative example 2 includes the following steps:

[0099] Step 1. Place a cleaned 2 mm thick glass substrate (with a 50 nm thick patterned transparent anode layer) on the bracket of a spin coater. Use a 0.45 μm filter to evenly coat the patterned transparent anode layer with PEDOT:PSS. Adjust the rotation speed of the spin coater to 1000 rpm to form a 50 nm thick anode interface layer of PEDOT:PSS on the surface of the transparent electrode. Heat it in a 120°C oven for 30 minutes.

[0100] Step 2: Transfer the above substrate to a glove box and place the substrate on the bracket of a spin coater. Evenly drop the mixed perovskite precursor solution on the anode interface layer. Adjust the spin coater speed to 5000 r / min. After spin coating for 1 minute, a 20 nm thick perovskite light-emitting layer is obtained.

[0101] The perovskite precursor solution was prepared as follows: dimethyl sulfoxide was used as solvent, inorganic perovskite CsPbCl3 was used as solute, the solution concentration was 10%, and the solution was heated and stirred at 60°C for 3 hours, and then the heating was stopped and the stirring was continued for 12 hours.

[0102] Step 3: Place the product obtained in step 2 into a vacuum coating machine and evacuate the vacuum. -4 Pa, a 50 nm thick TPBi cathode interface layer, a 2 nm thick LiF cathode interface modification layer, and a 20 nm thick Ag cathode layer were evaporated in sequence.

[0103] Comparative Example 3

[0104] The preparation method of the 3D perovskite light-emitting diode provided in this comparative example 3 comprises the following steps:

[0105] Step 1. Place a clean 5 mm thick quartz substrate (with a 200 nm thick patterned transparent anode layer) on the bracket of a spin coater. Use a 0.45 μm filter to evenly coat the patterned transparent anode layer with PEDOT:PSS. Adjust the rotation speed of the spin coater to 5000 rpm to form a 10 nm thick anode interface layer of PEDOT:PSS on the surface of the transparent electrode. Heat it in a 120°C oven for 30 minutes.

[0106] Step 2: Transfer the above substrate to a glove box and place the substrate on the bracket of a spin coater. Evenly drop the mixed perovskite precursor solution on the anode interface layer. Adjust the spin coater speed to 1000 r / min. After spin coating for 1 minute, a 200 nm thick perovskite light-emitting layer is obtained.

[0107] The perovskite precursor solution was prepared as follows: dimethyl sulfoxide was used as solvent, inorganic perovskite CsPbI3 was used as solute, the solution concentration was 40%, and the solution was heated and stirred at 60° C. for 3 hours, and then the heating was stopped and the stirring was continued for 12 hours.

[0108] Step 3: Place the product obtained in step 2 into a vacuum coating machine and evacuate the vacuum. -4 Pa, a 5 nm thick TPBi cathode interface layer, a 0.5 nm thick LiF cathode interface modification layer, and an 80 nm thick Al cathode layer were evaporated in sequence.

[0109] Comparative Example 4

[0110] The preparation method of the perovskite light-emitting diode of this comparative example 4 comprises the following steps:

[0111] Step 1. Place a cleaned 2 mm thick quartz substrate (with a 50 nm thick patterned transparent anode layer) on the bracket of a spin coater. Use a 0.45 μm filter to evenly coat the patterned transparent anode layer with PEDOT:PSS. Adjust the rotation speed of the spin coater to 1000 rpm to form a 50 nm thick anode interface layer of PEDOT:PSS on the surface of the transparent electrode. Heat it in a 120°C oven for 30 minutes.

[0112] Step 2: Transfer the above substrate to a glove box and place the substrate on the bracket of a spin coater. Evenly drop the mixed perovskite precursor solution on the anode interface layer. Adjust the spin coater speed to 5000 r / min. After spin coating for 1 minute, a 50 nm thick perovskite light-emitting layer is obtained.

[0113] The perovskite precursor solution was prepared as follows: dimethyl sulfoxide was used as solvent, inorganic perovskites CsPbCl3 and CsPbBr3 were used as solutes, the solution concentration was 20%, and the solution was heated and stirred at 60°C for 3 hours, and then the heating was stopped and the stirring was continued for 12 hours.

[0114] Step 3: Place the product obtained in step 2 into a vacuum coating machine and evacuate the vacuum. -4 At 1.5 Pa, a 50 nm thick TPBi cathode interface layer, a 3 nm thick LiF cathode interface modification layer and a 150 nm thick Ag cathode layer were evaporated in sequence.

[0115] Through the above multiple embodiments and comparative examples, it can be understood that:

[0116] from Figure 4a and Figure 4b It can be seen that in Comparative Example 1 without diethylamine hydrobromide doping, the grain size of the perovskite light-emitting layer is large and the coverage of the perovskite light-emitting layer is poor, while in Example 1 doped with diethylamine hydrobromide, the grain size of the perovskite light-emitting layer is significantly reduced, and obvious low-dimensional phase grains are generated, forming a 2D / 3D mixed phase distribution morphology in which 2D grains are tightly embedded in 3D grains, and the perovskite light-emitting layer is uniform and continuous with good coverage.

[0117] from Figure 5 It can be seen that the photoluminescence intensity of the perovskite light-emitting layer of Example 1 doped with diethylamine hydrobromide is significantly improved compared with the perovskite light-emitting layer of Comparative Example 1 without doping, indicating that diethylamine hydrobromide can effectively reduce the non-radiative recombination process caused by defects in the perovskite light-emitting layer, thereby improving the luminescence performance of the thin film.

[0118] from Figure 6 It can be seen that the photoluminescence spectrum broadening and multi-peak emission caused by the generation of the quasi-two-dimensional large n phase are well suppressed by the 2D / 3D heterophase structure, and only the 3D structure emits light in the electroluminescence spectrum, which shows that the quasi-two-dimensional large n phase caused by diethylamine hydrobromide will assist the 3D perovskite structure to emit light.

[0119] from Figure 7a and Figure 7b It can be seen that compared with Comparative Example 1, Example 1 has a higher current density at the same voltage, indicating that it has a smaller leakage current and a higher brightness, which shows that doping with diethylamine hydrobromide effectively improves the luminescent performance of the perovskite light-emitting layer.

[0120] from Figure 8 It can be seen that compared with Comparative Example 1, Example 1 has a higher external quantum efficiency at the same voltage, which shows that doping with diethylamine hydrobromide effectively improves the luminous efficiency of the device.

[0121] On the other hand, Table 1 shown below compares the luminous performance parameters of Comparative Examples 1, 2, 3, 4 and Examples 1, 2, 3, 4, and 5. Compared with Comparative Example 1, Example 1 has higher brightness, current efficiency, and lifespan (35,000 candelas per square meter, 16.5 candelas per ampere, and 6 minutes). Similarly, compared with Comparative Examples 2, 3, and 4, Examples 2, 3, 4, and 5 also have higher brightness, current efficiency, and lifespan, respectively. This shows that each embodiment of the present invention has more outstanding luminous performance and stability than its corresponding comparative example, thereby illustrating that the method of the present invention has obvious advantages in improving the performance of perovskite light-emitting diodes.

[0122] Table 1

[0123]

[0124]

[0125] In the description of this specification, the reference terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0126] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0127] The above specific embodiments of the present invention do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A 3D perovskite light-emitting diode, comprising a patterned transparent anode layer, an anode interface layer, a perovskite light-emitting layer, a cathode interface layer, a cathode interface modification layer, and a cathode layer sequentially prepared on a substrate, characterized in that: The perovskite light-emitting layer is doped with an ionic compound containing an imino group, and the ionic compound containing an imino group acts as an organic spacer to induce the formation of 2D grains close to the 3D grain size inside the perovskite light-emitting layer, so that the perovskite light-emitting layer becomes a 2D / 3D heterophase perovskite structure; the ionic compound containing an imino group is diethylamine hydrobromide, methylethylamine hydrobromide, dipropylamine hydrobromide, diisopropylamine hydrobromide or dibutylamine hydrobromide.

2. The 3D perovskite light-emitting diode according to claim 1, wherein The perovskite light-emitting layer is any one of inorganic perovskites CsPbBr3, CsPbCl3 or CsPbI3, or a combination of two or more thereof.

3. The 3D perovskite light-emitting diode according to claim 1, wherein The patterned transparent anode layer is an indium tin oxide electrode with a thickness of 50-200 nm.

4. The 3D perovskite light-emitting diode according to claim 1, wherein The anode interface layer is PEDOT:PSS with a thickness of 10-50 nm.

5. The 3D perovskite light-emitting diode according to claim 1, wherein The cathode interface layer is TPBi with a thickness of 5-50 nm.

6. The 3D perovskite light-emitting diode according to claim 1, wherein: The cathode interface modification layer is lithium fluoride and has a thickness of 0.5-3 nm.

7. The 3D perovskite light-emitting diode according to claim 1, wherein: The cathode layer is made of aluminum or silver, and has a thickness of 20-150 nm.

8. A method for preparing a 3D perovskite light-emitting diode according to any one of claims 1 to 7, comprising the following steps: S1, preparing a patterned transparent anode layer on a substrate; S2, preparing an anode interface layer on the patterned transparent anode layer; S3, growing a perovskite light-emitting layer on the anode interface layer; S4, sequentially preparing a cathode interface layer, a cathode interface modification layer, and a cathode layer on the perovskite light-emitting layer by evaporation; It is characterized in that When growing the perovskite light-emitting layer, an ionic compound containing an imino group is added to the perovskite precursor solution. The ionic compound containing an imino group acts as an organic spacer to induce the formation of 2D grains close to the 3D grain size inside the perovskite light-emitting layer, so that the perovskite light-emitting layer becomes a 2D / 3D heterophase perovskite structure; the ionic compound containing an imino group is diethylamine hydrobromide, methylethylamine hydrobromide, dipropylamine hydrobromide, diisopropylamine hydrobromide or dibutylamine hydrobromide.

9. The method for preparing a 3D perovskite light-emitting diode according to claim 8, wherein: The preparation method of the perovskite precursor solution is as follows: Using DMSO as a solvent and any one or a combination of two or more of the inorganic perovskites CsPbBr3, CsPbCl3 or CsPbI3 as a solute, an ionic compound containing an imino group at a concentration of 1 mg / mL-40 mg / mL is added to the solute, and the solvent and the solute are fully stirred at 20°C-80°C to form the perovskite precursor solution.

10. The method for preparing a 3D perovskite light-emitting diode according to claim 9, wherein: Step S2 specifically includes the following steps: S21, placing the cleaned substrate with a patterned transparent anode layer having a thickness of 50-200 nm on a bracket of a spin coater; S22, adjusting the rotation speed of the spin coater to 1000-5000 r / min, so that the PEDOT:PSS solution is evenly coated on the patterned transparent anode layer and forms the anode interface layer on the surface of the patterned transparent anode layer; Step S3 specifically includes the following steps: S31, preparing a perovskite precursor solution, adding an ionic compound containing an imine group to the perovskite precursor solution; S32, evenly spin-coating the perovskite precursor solution on the surface of the anode interface layer at a spin-coating speed of 1000-5000 r / min; S33, placing the substrate on which the perovskite precursor solution is spin-coated on a hot stage for annealing to form the perovskite light-emitting layer, forming 2D grains close to the size of 3D grains in the perovskite light-emitting layer, and the 2D grains and the 3D grains are mixed and distributed in the perovskite light-emitting layer; Step S4 specifically includes the following steps: The substrate with the perovskite light-emitting layer was placed in a vacuum coating machine for vacuum treatment. When the vacuum degree reached 4×10 - 4 Pa, a cathode interface layer, a cathode interface modification layer and a cathode layer are sequentially evaporated on the surface of the perovskite light-emitting layer.

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