Perovskite light-emitting diode with ionic liquid buried bottom interface and preparation method and application of perovskite light-emitting diode

Abstract

The invention discloses a perovskite light-emitting diode with an ionic liquid buried interface and a preparation method and application of the perovskite light-emitting diode. The preparation method comprises the following steps: spin-coating an electron transport layer on the surface of an ITO conductive substrate, depositing a buried interface material formamidine acetate (FAAc) ionic liquid on the electron transport layer, annealing to obtain an FAAc buried interface, and spin-coating a perovskite precursor solution based on the FAAc buried interface to obtain a compact and flat perovskite thin film; and a hole transport layer, an interface modification layer and a metal electrode are sequentially arranged on the perovskite thin film. Through ionic liquid buried interface modification, the formation of the perovskite thin film is optimized, the vertical growth of perovskite is promoted, and the cleanliness is improved; passivation of vacancy defects of halide is facilitated, and interface non-radiative recombination is inhibited; meanwhile, the energy level of the zinc oxide electron transmission layer is adjusted, and electron transmission and injection are enhanced. While the efficiency of the PeLED is improved, the stability of the PeLED is improved, and the efficiency roll-off is inhibited.

Description

Technical Field

[0001] The present invention relates to the technical field of perovskite light-emitting diodes, and in particular to a perovskite light-emitting diode with an ionic liquid buried bottom interface and a preparation method and application thereof. Background Art

[0002] Metal halide perovskites have attracted significant attention in the field of light-emitting diodes (PeLEDs) due to their exceptional properties, such as high color purity, tunable emission wavelength, and high charge mobility. Since the first room-temperature electroluminescent perovskite light-emitting diode (PeLED) was demonstrated in 2014, the external quantum efficiency (EQE) of perovskite-based LEDs has reached nearly 30% in just a few years, with emission colors ranging from blue to near-infrared, demonstrating great potential for future commercial applications. For example, near-infrared (700-2500 nm) PeLEDs have broad applicability in fields such as biomedical imaging, remote sensing, and night vision.

[0003] A prerequisite for fabricating high-performance PeLEDs is the realization of high-quality perovskite crystal films. To achieve uniform and dense perovskite crystal films with low defect density, researchers have explored several approaches, including A-site cation doping, size manipulation, and chemical composition manipulation. In addition to optimizing perovskite precursors, interface modification also plays a key role in improving PeLED performance. This is because numerous defects, particularly vacancies and interstitial defects, are easily formed at the interface between the perovskite film and the transport layer, leading to severe non-radiative recombination losses. Furthermore, these defects can serve as decomposition centers for the perovskite film, causing irreversible degradation and reduced device stability. To date, most interface modulation strategies have focused on the upper interface, primarily due to its ease of manipulation compared to the lower interface. However, the buried interface is the starting point for perovskite crystal film growth, and its quality and properties directly determine the quality of the resulting perovskite film. Therefore, exploring effective buried interface engineering strategies is crucial. These strategies not only enhance the crystalline quality of the perovskite film but also passivate defects and improve charge injection efficiency, thereby enhancing PeLED device performance. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention proposes a perovskite light-emitting diode with an ionic liquid buried bottom interface and a preparation method and application thereof.

[0005] In order to solve the above technical problems, the technical solution proposed in the present invention is: a perovskite light-emitting diode with an ionic liquid buried interface, comprising an ITO conductive substrate, wherein the surface of the ITO conductive substrate is sequentially provided with a zinc oxide electron transport layer and a polyethoxyethyleneimine (PEIE) modification layer, the surface of the polyethoxyethyleneimine modification layer away from the zinc oxide electron transport layer is sequentially provided with a formamidine acetate interface layer (FAAc interface layer) and a perovskite film, the surface of the perovskite film away from the FAAc interface layer is provided with a hole transport layer, and the surface of the hole transport layer away from the perovskite film is sequentially provided with an interface modification layer and a metal electrode.

[0006] Furthermore, the interface modification layer is MoO3 with a thickness of 6-10 nm.

[0007] Furthermore, the metal electrode is Ag, and has a thickness of 80-120 nm.

[0008] Furthermore, the hole transport layer is 1,2,4,5-tetrakis(trifluoromethyl)benzene (TFB).

[0009] The present invention also provides a method for preparing a perovskite light-emitting diode with an ionic liquid buried bottom interface, comprising the following steps:

[0010] Step 1: Fully dissolve the perovskite composition in N,N-dimethylformamide to prepare a perovskite precursor solution; heat and dissolve formamidine acetate (FAAc) in another portion of N,N-dimethylformamide to prepare a FAAc solution;

[0011] Step 2: Clean the ITO conductive substrate, and spin-coat a zinc oxide electron transport material on the ITO conductive substrate to form a zinc oxide electron transport layer, and then spin-coat polyethoxyethyleneimine to form a polyethoxyethyleneimine modified layer;

[0012] Step 3: Spin-coating FAAc solution on the ITO conductive substrate spin-coated with the polyethoxyethyleneimine modified layer, and then annealing to obtain a FAAc interface layer;

[0013] Step 4: Spin-coating the perovskite precursor solution on the FAAc interface layer and annealing to obtain a dense and uniform perovskite film;

[0014] Step 5: Spin-coating a hole transport layer material on the perovskite film to obtain a hole transport layer; then vacuum thermal evaporation is performed on the hole transport layer to obtain an interface modification layer and a metal electrode in sequence, thereby obtaining the perovskite light-emitting diode.

[0015] Further, in step 1, the perovskite composition includes at least one of lead iodide (PbI2), formamidine iodide (FAI), lead iodide (PbI2), cesium iodide (CsI), lead bromide (PbBr2), and 2,2′-[oxybis(ethyleneoxy)]diethylamine] (ODEA).

[0016] Furthermore, in step 1, the perovskite composition is prepared by mixing formamidine iodide (FAI), lead iodide (PbI2) and 2,2′-[oxybis(ethyleneoxy)]diethylamine] (ODEA) in a molar ratio of 2.1:1:0.3.

[0017] Furthermore, the perovskite composition is a mixture of a combination of formamidine iodide and cesium iodide (FAI+CsI), a combination of lead iodide and lead bromide (PbI2+PbBr2), and 2,2′-[oxybis(ethyleneoxy)]diethylamine] (ODEA) in a molar ratio of 2.1:1:0.3, wherein the molar ratio of formamidine iodide and cesium iodide in the combination of formamidine iodide and cesium iodide is 0.17:0.83, and the molar ratio of lead iodide and lead bromide in the combination of lead iodide and lead bromide is 0.75:0.25.

[0018] Furthermore, in step 2, a zinc oxide electron transport material is spin-coated for 20-40 seconds at a spin coating speed of 3500-4500 r / min and annealed at 140-160° C. for at least 10 minutes to obtain a zinc oxide electron transport layer; then, a polyethoxyethyleneimine solution dissolved in 2-methoxyethanol is spin-coated on the zinc oxide electron transport layer for 20-40 seconds at a spin coating speed of 4500-5500 r / min and annealed at 90-110° C. for at least 10 minutes to obtain a polyethoxyethyleneimine modified layer.

[0019] Furthermore, in step 3, the FAAc solution prepared in step 1 is spin-coated on the polyethoxyethyleneimine modified layer at a spin-coating speed of 3500-4500 r / min for 20-40 s, and annealed at 90-110° C. for at least 10 min to obtain a FAAc interface layer.

[0020] Furthermore, in step 5, 12 mg of 1,2,4,5-tetrakis(trifluoromethyl)benzene was dissolved in 1 mL of chlorobenzene to prepare a hole transport layer material spin coating solution, and the solution was spin coated on the perovskite film at a spin coating speed of 4000-5000 r / min for 40-50 s to obtain a hole transport layer.

[0021] In summary, compared with the prior art, the present invention has achieved the following technical effects: the present invention uses interface engineering to modify the buried interface to regulate the growth of perovskite crystals in PeLED and suppress the problem of buried interface defects, PEIE and FA+ The in-situ deprotonation reaction and hydrogen bond formation between FAAc and FAAc provide pre-nucleation sites for perovskite growth, thereby significantly improving the orientation, crystallinity and morphology of the perovskite film. The C=O in Ac- can effectively passivate the iodine vacancy defect sites, thereby reducing the defect-mediated non-radiative recombination, thereby greatly improving the quality of the perovskite film, as well as the brightness and efficiency. In addition, the positively charged FA in FAAc + This method effectively passivates oxygen vacancy defects in zinc oxide, modulates the zinc oxide energy level, facilitates alignment with the perovskite energy level, suppresses non-radiative recombination at the interface, and enhances electron injection. This approach enables efficient and stable near-infrared PeLEDs, enhancing device operational stability and suppressing efficiency roll-off. The proposed ionic liquid-buried interface strategy demonstrates considerable versatility and effectiveness in enhancing the operational stability of perovskite light-emitting diodes, potentially contributing to the commercialization of perovskite light-emitting diodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0023] Figure 1a Schematic diagram of a perovskite light-emitting diode device prepared in Example 1 of the present invention, wherein MoO3 / Ag refers to the interface modification layer and the metal electrode, FAPbI3 refers to the perovskite film, FAAc refers to the FAAc interface layer, ZnO / PEIE refers to the zinc oxide electron transport layer and the polyethoxyethyleneimine modification layer, and ITO / Glass refers to the ITO conductive substrate;

[0024] Figure 1b Schematic diagram of a perovskite light-emitting diode device prepared in Comparative Example 1 of the present invention;

[0025] Figure 2 1 is an irradiance-voltage curve of the perovskite light-emitting diodes prepared in Example 1 of the present invention and Comparative Example 1;

[0026] Figure 3 1 is an external quantum efficiency-current density curve of the perovskite light-emitting diodes prepared in Example 1 of the present invention and Comparative Example 1;

[0027] Figure 4 Graph showing T50 lifespan of the perovskite light-emitting diodes prepared in Example 1 of the present invention and Comparative Example 1;

[0028] Figure 5aSchematic diagram of a perovskite light-emitting diode device prepared in Example 2 of the present invention;

[0029] Figure 5b Schematic diagram of a perovskite light-emitting diode device prepared in Comparative Example 2 of the present invention;

[0030] Figure 6 irradiance-voltage curves of the perovskite light-emitting diodes prepared in Example 2 of the present invention and Comparative Example 2;

[0031] Figure 7 2 is an external quantum efficiency-current density curve of the perovskite light-emitting diodes prepared in Example 2 of the present invention and Comparative Example 2. DETAILED DESCRIPTION

[0032] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0033] Example 1

[0034] This embodiment provides a method for preparing a perovskite light-emitting diode with an ionic liquid buried bottom interface, comprising the following steps:

[0035] Step 1: FAI, PbI2, and ODEA were mixed in a molar ratio of 2.1:1:0.3, dissolved in N,N-dimethylformamide, and heated and stirred at 60°C on a hot plate in an N2 glove box for 2 hours to prepare a FAPbI3 perovskite precursor solution; 8 mg of formamidine acetate was dissolved in another 1 mL of N,N-dimethylformamide, and then stirred on a hot plate in an N2 glove box at 60°C for 6 hours to prepare a FAAc solution;

[0036] Step 2: Clean the ITO conductive substrate, ultrasonicate the ITO conductive substrate in ethanol, detergent, ultrapure water and ethanol for 15 minutes each, blow dry with nitrogen to obtain a clean ITO conductive substrate, and then treat with ultraviolet ozone for 20 minutes; spin-coat a zinc oxide nanocrystal solution on the ITO conductive substrate at 4000 r / min for 30 seconds, and thermally anneal on a hot stage in an N2 glove box at 150° C. for 10 minutes to form a zinc oxide electron transport layer, and then spin-coat a polyethoxyethyleneimine solution (0.4wt%) dissolved in 2-methoxyethanol on the zinc oxide electron transport layer at 5000 r / min for 30 seconds, and thermally anneal on a hot stage in an N2 glove box at 100° C. for 10 minutes to form a polyethoxyethyleneimine modification layer;

[0037] Step 3: In a N2 glove box, the FAAc solution prepared in step 1 was spin-coated on the polyethoxyethyleneimine modified layer at 4000 rpm for 30 seconds, and then thermally annealed on a hot plate in the N2 glove box at 100°C for 10 minutes to obtain a FAAc interface layer;

[0038] Step 4: Spin-coat the FAPbI3 perovskite precursor solution prepared in step 1 on the FAAc interface layer in an N2 glove box and thermally anneal at 100°C for 10 minutes on a hot plate in the N2 glove box to obtain a dense and uniform FAPbI3 perovskite film.

[0039] Step 5: Dissolve 12 mg of TFB in 1 mL of CB to prepare a hole transport layer spin coating solution, and spin-coat the hole transport layer spin coating solution on the FAPbI3 perovskite film at 4500 rpm for 45 seconds to obtain a hole transport layer; then, vacuum thermal evaporation is performed on the hole transport layer to obtain an interface modification layer MoO3 with a thickness of 8 nm and a metal electrode Ag with a thickness of 100 nm, thereby obtaining the perovskite light-emitting diode.

[0040] The structure of the perovskite light-emitting diode device prepared by the above preparation method in this embodiment is as follows: Figure 1a shown.

[0041] Example 2

[0042] This embodiment provides a method for preparing a perovskite light-emitting diode with an ionic liquid buried bottom interface, comprising the following steps:

[0043] Step 1: (FAI+CsI), (PbI2+PbBr2) and ODEA were mixed in a molar ratio of 2.1:1:0.3, wherein the ratio of FAI to CsI was 0.17:0.83, and the ratio of PbI2 to PbBr2 was 0.75:0.25, dissolved in N,N-dimethylformamide, and heated and stirred at 60 ° C for 2 h on a hot stage in an N2 glove box to prepare CsI. 0.17 FA 0.83 Pb(I 0.75 Br 0.25 )3 Perovskite precursor solution; 8 mg of formamidine acetate was dissolved in another 1 mL of N,N-dimethylformamide, and then stirred on a hot plate in an N2 glove box at 60°C for 6 h to prepare a FAAc solution;

[0044] Step 2: Clean the ITO conductive substrate, ultrasonicate the ITO conductive substrate in ethanol, detergent, ultrapure water and ethanol for 15 minutes each, blow dry with nitrogen to obtain a clean ITO conductive substrate, and then treat with ultraviolet ozone for 20 minutes; spin-coat a zinc oxide nanocrystal solution on the ITO conductive substrate at 4000 r / min for 30 seconds, and thermally anneal on a hot stage in an N2 glove box at 150° C. for 10 minutes to form a zinc oxide electron transport layer, and then spin-coat a polyethoxyethyleneimine solution (0.4wt%) dissolved in 2-methoxyethanol on the zinc oxide electron transport layer at 5000 r / min for 30 seconds, and thermally anneal on a hot stage in an N2 glove box at 100° C. for 10 minutes to form a polyethoxyethyleneimine modification layer;

[0045] Step 3: In a N2 glove box, the FAAc solution prepared in step 1 was spin-coated on the polyethoxyethyleneimine modified layer at 4000 rpm for 30 seconds, and then thermally annealed on a hot plate in the N2 glove box at 100°C for 10 minutes to obtain a FAAc interface layer;

[0046] Step 4: In a N2 glove box, the Cs prepared in step 1 0.17 FA 0.83 Pb(I 0.75 Br 0.25 )3 The perovskite precursor solution was spin-coated on the FAAc interface layer and thermally annealed on a hot plate in a N2 glove box at 100 ° C for 10 min to obtain a dense and uniform Cs 0.17 FA 0.83 Pb(I 0.75 Br 0.25 )3Perovskite film;

[0047] Step 5: Dissolve 12 mg of TFB in 1 mL of CB to prepare a hole transport layer spin coating solution, and spin coat the hole transport layer spin coating solution on the Cs substrate at 4500 r / min. 0.17 FA 0.83 Pb(I 0.75 Br 0.25 )3 perovskite film for 45s to obtain a hole transport layer; then, on the hole transport layer, an interface modification layer MoO3 with a thickness of 8nm and a metal electrode Ag with a thickness of 100nm were obtained by vacuum thermal evaporation, that is, the Cs 0.17 FA 0.83 Pb(I 0.75 Br 0.25 )3 mixed halide perovskite light emitting diodes.

[0048] In this example, Cs 0.17 FA 0.83 Pb(I0.75 Br 0.25 )3 The structure of the mixed halogen perovskite light-emitting diode device is as follows Figure 5a shown.

[0049] Comparative Example 1

[0050] This comparative example provides a method for preparing a perovskite light-emitting diode, comprising the following steps:

[0051] Step 1: FAI, PbI2, and ODEA were mixed in a molar ratio of 2.1:1:0.3, dissolved in N,N-dimethylformamide, and heated and stirred at 60°C on a hot plate in an N2 glove box for 2 h to prepare a FAPbI3 perovskite precursor solution;

[0052] Step 2: Clean the ITO conductive substrate, ultrasonicate the ITO conductive substrate in ethanol, detergent, ultrapure water and ethanol for 15 minutes each, blow dry with nitrogen to obtain a clean ITO conductive substrate, and then treat with ultraviolet ozone for 20 minutes; spin-coat a zinc oxide nanocrystal solution on the ITO conductive substrate at 4000 r / min for 30 seconds, and thermally anneal on a hot stage in an N2 glove box at 150° C. for 10 minutes to form a zinc oxide electron transport layer, and then spin-coat a polyethoxyethyleneimine solution (0.4wt%) dissolved in 2-methoxyethanol on the zinc oxide electron transport layer at 5000 r / min for 30 seconds, and thermally anneal on a hot stage in an N2 glove box at 100° C. for 10 minutes to form a polyethoxyethyleneimine modification layer;

[0053] Step 3: Spin-coat the perovskite precursor solution prepared in step 1 on the polyethoxyethyleneimine modified layer in an N2 glove box and anneal it on a hot plate in the N2 glove box at 100°C for 10 minutes to obtain a dense and uniform FAPbI3 perovskite film.

[0054] Step 4: 12 mg of TFB was dissolved in 1 mL of CB to prepare a hole transport layer spin coating solution, and the hole transport layer spin coating solution was spin coated on the FAPbI3 perovskite film at 4500 r / min for 45 seconds to obtain a hole transport layer; then, an interface modification layer MoO3 with a thickness of 8 nm and a metal electrode Ag with a thickness of 100 nm were successively obtained on the hole transport layer by vacuum thermal evaporation to obtain the perovskite light-emitting diode.

[0055] The structure of the perovskite light-emitting diode prepared by the above preparation method in this comparative example is as follows: Figure 1b Compared with Example 1, the perovskite light-emitting diode of this comparative example does not contain a FAAc interface layer.

[0056] The relationship between the irradiance and voltage of the perovskite light-emitting diode devices prepared in Example 1 of the present invention and Comparative Example 1 is as follows: Figure 2 As shown, the relationship between the external quantum efficiency and current density of the perovskite light-emitting diode devices prepared in Example 1 and Comparative Example 1 is as follows: Figure 3 As shown in the figure, the maximum irradiance of the perovskite light-emitting diode device prepared in Example 1 is 278.62W sr -1 m -2 , its external quantum efficiency is 23.84%; while the maximum irradiance of the perovskite light-emitting diode device prepared in Comparative Example 1 is 37.31W sr -1 m -2 , and its external quantum efficiency is 18.63%. In addition, the T 50 The life curve is as follows Figure 4 As shown, at 50mA / cm 2 At a high current density of , the perovskite light-emitting diode prepared in Example 1 continuously works T 50 The lifetime is 24h, while the perovskite light-emitting diode prepared in Comparative Example 1 works continuously for 50 The lifetime is 2.2h. This shows that the buried FAAc ionic liquid interface layer has a significant effect on improving the irradiance, external quantum efficiency and stability of the perovskite diode device.

[0057] Comparative Example 2

[0058] This comparative example provides a method for preparing a perovskite light-emitting diode, comprising the following steps:

[0059] Step 1: (FAI+CsI), (PbI2+PbBr2) and ODEA were mixed in a molar ratio of 2.1:1:0.3, wherein the ratio of FAI to CsI was 0.17:0.83, and the ratio of PbI2 to PbBr2 was 0.75:0.25, dissolved in N,N-dimethylformamide, and heated and stirred at 60 ° C for 2 h on a hot stage in an N2 glove box to prepare CsI. 0.17 FA 0.83 Pb(I 0.75 Br 0.25 )3 Perovskite precursor solution; 8 mg of formamidine acetate was dissolved in another 1 mL of N,N-dimethylformamide, and then stirred on a hot plate in an N2 glove box at 60°C for 6 h to prepare a FAAc solution;

[0060] Step 2: Clean the ITO conductive substrate, ultrasonicate the ITO conductive substrate in ethanol, detergent, ultrapure water and ethanol for 15 minutes each, blow dry with nitrogen to obtain a clean ITO conductive substrate, and then treat with ultraviolet ozone for 20 minutes; spin-coat a zinc oxide nanocrystal solution on the ITO conductive substrate at 4000 r / min for 30 seconds, and thermally anneal on a hot stage in an N2 glove box at 150° C. for 10 minutes to form a zinc oxide electron transport layer, and then spin-coat a polyethoxyethyleneimine solution (0.4wt%) dissolved in 2-methoxyethanol on the zinc oxide electron transport layer at 5000 r / min for 30 seconds, and thermally anneal on a hot stage in an N2 glove box at 100° C. for 10 minutes to form a polyethoxyethyleneimine modification layer;

[0061] Step 3: In a N2 glove box, the Cs prepared in step 1 0.17 FA 0.83 Pb(I 0.75 Br 0.25 )3 The perovskite precursor solution was spin-coated on the polyethoxyethyleneimine modified layer and thermally annealed at 100 ° C for 10 min in a hot stage in a N2 glove box to obtain a dense and uniform Cs 0.17 FA 0.83 Pb(I 0.75 Br 0.25 )3Perovskite film;

[0062] Step 4: Dissolve 12 mg of TFB in 1 mL of CB to prepare a hole transport layer spin coating solution, and spin coat the hole transport layer spin coating solution on the Cs substrate at 4500 r / min. 0.17 FA 0.83 Pb(I 0.75 Br 0.25 )3 perovskite film for 45s to obtain a hole transport layer; then, an interface modification layer MoO3 with a thickness of 8nm and a metal electrode Ag with a thickness of 100nm are obtained on the hole transport layer by vacuum thermal evaporation, thereby obtaining the perovskite light-emitting diode.

[0063] The structure of the perovskite light-emitting diode prepared by the above preparation method in this comparative example is as follows: Figure 5b Compared with Example 2, the perovskite light-emitting diode of this comparative example does not contain a FAAc interface layer.

[0064] Cs prepared in Example 2 of the present invention and Comparative Example 2 0.17 FA 0.83 Pb(I 0.75 Br 0.25 )3 The relationship between irradiance and voltage of mixed halide perovskite light-emitting diode devices is as follows Figure 6As shown, the relationship between the external quantum efficiency and current density of the perovskite light-emitting diode devices prepared in Example 2 and Comparative Example 2 is as follows: Figure 7 As shown in the figure, the maximum irradiance of the perovskite light-emitting diode device prepared in Example 2 is 293.3W sr -1 m -2 , and its external quantum efficiency is 18.8%; while the maximum irradiance of the perovskite light-emitting diode device prepared in Comparative Example 2 is 141.0W sr -1 m -2 , with an external quantum efficiency of 12.93%. This demonstrates that the buried FAAc interface layer has potential in interface modification. It is a versatile and effective interface modification strategy that can improve the performance of different types of perovskite light-emitting diodes and is expected to be more widely used in the field of optoelectronic devices.

[0065] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A perovskite light-emitting diode with an ionic liquid buried bottom interface, characterized in that: The invention comprises an ITO conductive substrate, wherein a zinc oxide electron transport layer and a polyethoxyethyleneimine modification layer are sequentially provided on the surface of the ITO conductive substrate, a formamidine acetate interface layer and a perovskite film are sequentially provided on the surface of the polyethoxyethyleneimine modification layer away from the zinc oxide electron transport layer, a hole transport layer is provided on the surface of the perovskite film away from the formamidine acetate interface layer, and an interface modification layer and a metal electrode are sequentially provided on the surface of the hole transport layer away from the perovskite film.

2. The perovskite light-emitting diode with an ionic liquid buried bottom interface according to claim 1, characterized in that: The interface modification layer is MoO3 and has a thickness of 6-10 nm.

3. The perovskite light-emitting diode with an ionic liquid buried bottom interface according to claim 1, characterized in that: The metal electrode is Ag, and has a thickness of 80-120 nm.

4. The method for preparing a perovskite light-emitting diode with an ionic liquid buried bottom interface according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step 1: Fully dissolving the perovskite composition in N,N-dimethylformamide to prepare a perovskite precursor solution; heating and dissolving formamidine acetate in another portion of N,N-dimethylformamide to prepare a formamidine acetate solution; Step 2: Clean the ITO conductive substrate, and spin-coat a zinc oxide electron transport material on the ITO conductive substrate to form a zinc oxide electron transport layer, and then spin-coat polyethoxyethyleneimine to form a polyethoxyethyleneimine modified layer; Step 3: Spin-coating a formamidine acetate solution on the ITO conductive substrate spin-coated with a polyethoxyethyleneimine modified layer, and then annealing to obtain a formamidine acetate interface layer; Step 4: Spin-coating the perovskite precursor solution on the formamidine acetate interface layer, and obtaining a dense and uniform perovskite film after annealing; Step 5: Spin-coating a hole transport layer material on the perovskite film to obtain a hole transport layer; then vacuum thermal evaporation is performed on the hole transport layer to obtain an interface modification layer and a metal electrode in sequence, thereby obtaining the perovskite light-emitting diode.

5. The method for preparing a perovskite light-emitting diode with an ionic liquid buried bottom interface according to claim 4, characterized in that: In step 1, the perovskite composition includes at least one of lead iodide, formamidine iodide, lead iodide, cesium iodide, lead bromide, and 2,2′-[oxybis(ethyleneoxy)]diethylamine].

6. The method for preparing a perovskite light-emitting diode with an ionic liquid buried bottom interface according to claim 5, characterized in that: In step 1, the perovskite composition is prepared by mixing formamidine iodide, lead iodide, and 2,2′-[oxybis(ethyleneoxy)]diethylamine] in a molar ratio of 2.1:1:0.

3.

7. The method for preparing a perovskite light-emitting diode with an ionic liquid buried bottom interface according to claim 5, characterized in that: The perovskite composition is formed by mixing a combination of formamidine iodide and cesium iodide, a combination of lead iodide and lead bromide, and 2,2′-[oxybis(ethyleneoxy)]diethylamine] in a molar ratio of 2.1:1:0.3, wherein the molar ratio of formamidine iodide and cesium iodide in the combination of formamidine iodide and cesium iodide is 0.17:0.83, and the molar ratio of lead iodide and lead bromide in the combination of lead iodide and lead bromide is 0.75:0.

25.

8. The method for preparing a perovskite light-emitting diode with an ionic liquid buried bottom interface according to claim 4, characterized in that: In step 2, a zinc oxide electron transport material is spin-coated for 20-40 seconds at a spin-coating speed of 3500-4500 r / min and annealed at 140-160° C. for at least 10 minutes to obtain a zinc oxide electron transport layer; then, a polyethoxyethyleneimine solution dissolved in 2-methoxyethanol is spin-coated on the zinc oxide electron transport layer at a spin-coating speed of 4500-5500 r / min for 20-40 seconds and annealed at 90-110° C. for at least 10 minutes to obtain a polyethoxyethyleneimine modified layer.

9. The method for preparing a perovskite light-emitting diode with an ionic liquid buried bottom interface according to claim 4, characterized in that: In step 3, the FAAc solution prepared in step 1 is spin-coated on the polyethoxyethyleneimine modified layer at a spin-coating speed of 3500-4500 r / min for 20-40 seconds, and annealed at 90-110° C. for at least 10 minutes to obtain a formamidine acetate interface layer.

10. The method for preparing a perovskite light-emitting diode with an ionic liquid buried bottom interface according to claim 4, characterized in that: In step 5, 1,2,4,5-tetrakis(trifluoromethyl)benzene is dissolved in chlorobenzene to prepare a hole transport layer material spin coating solution, and the solution is spin coated on the perovskite film at a spin coating speed of 4000-5000 r / min for 40-50 seconds to obtain a hole transport layer.

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