Environment-friendly quasi-two-dimensional tin-based perovskite deep red light LED device and preparation method and application thereof

Abstract

The invention relates to an environment-friendly quasi-two-dimensional tin-based perovskite deep red light LED device and a preparation method and application thereof. The device comprises an anode, a hole transport layer, a perovskite light-emitting layer, an electron transport layer, an electron injection layer and a cathode which are stacked in sequence. The perovskite light-emitting layer is a quasi-two-dimensional tin-based perovskite thin film, the chemical formula of the perovskite light-emitting layer is TEA2FASn2I7, and TEA is 2-thiophene ethyl ammonium cation. According to the preparation method, the high-quality quasi-two-dimensional tin-based perovskite thin film of which the emission peak is positioned in a dark red light region of about 690 nm and the half-peak width is less than 60 nm is prepared by performing interface modification on the hole transport layer and regulating and controlling the components and crystallization kinetics of the perovskite precursor solution. The problem that a quasi-two-dimensional phase is difficult to control due to too fast crystallization of a visible light band tin-based perovskite LED in the prior art is solved, meanwhile, the toxicity of a lead-based material is avoided, and the tin-based perovskite LED has the advantages of being high in color purity, environmentally friendly and simple in preparation process and is suitable for the fields of high-resolution display, biological detection and the like.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronic technology, specifically to an environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED device, its fabrication method, and its application. Background Technology

[0002] With the development of new display technologies, machine vision, and medical and health monitoring, the demand for high-performance luminescent materials is increasing. Perovskite materials, due to their excellent photoelectric properties, have received widespread attention and research in recent years. Among them, lead-based perovskite materials, with their high absorption coefficient, long carrier diffusion length, tunable band gap, and high color purity, show promising application prospects in light-emitting devices. However, the biotoxicity of lead ions and the water solubility of their degradation products pose potential hazards to the environment and organisms. Therefore, the development of environmentally friendly lead-free perovskite materials is of great significance.

[0003] Tin-based perovskite materials have become a research hotspot due to their photoelectric properties similar to lead-based materials. Although significant progress has been made in tin-based near-infrared light-emitting diodes (LEDs), the development of tin-based visible light LEDs still faces limitations, failing to fully meet the performance requirements of visible light sources in fields such as novel displays and medical and health monitoring. This is mainly attributed to the rapid crystallization process of tin-based perovskite materials. In conventional spin-coating processes, the three-dimensional phase with near-infrared emission readily forms, making the fabrication of quasi-two-dimensional visible light perovskite materials difficult. Currently reported quasi-two-dimensional tin-based perovskite LED devices only involve near-infrared light devices, and their luminous efficiency, stability, and color performance remain limited, failing to meet the requirements of high-end display and high-precision detection applications. Summary of the Invention

[0004] The purpose of this invention is to provide a quasi-two-dimensional tin-based perovskite visible light LED device that overcomes the problems of poor film quality, low luminous efficiency, and high toxicity of lead-based materials in the prior art due to the difficulty in controlling the crystallization kinetics of tin-based perovskite visible light LEDs. The invention provides a quasi-two-dimensional tin-based perovskite deep red light LED device with high color purity and environmental friendliness, which has an emission wavelength in the deep red light band. The invention also includes its preparation method and application.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: an environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED device, comprising an anode, a hole transport layer, a perovskite light-emitting layer, an electron transport layer, an electron injection layer, and a cathode stacked sequentially; the perovskite light-emitting layer is a quasi-two-dimensional tin-based perovskite thin film with the chemical formula TEA2FASn2I7, wherein TEA is a 2-thiophene ethylammonium cation.

[0006] Further, the anode material is indium tin oxide (ITO); the hole transport layer is a zinc acetate-modified poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (m-PEDOT:PSS) film; the electron transport layer material is 2,2',2"-(1,3,5-phenyl)-tris(1-phenyl-1H-benzimidazole) (TPBi); the electron injection layer material is lithium fluoride (LiF); and the cathode material is aluminum (Al) or silver (Ag).

[0007] This LED device uses a quasi-two-dimensional tin-based perovskite material (TEA2FASn2I7) as the emitting layer. The crystallization process of the thin film is synergistically controlled by modifying the hole transport layer interface (e.g., using zinc acetate to modify PEDOT:PSS), combining specific precursor components (introducing CsI to adjust stress and AD additives to passivate defects) and controlling the crystallization environment (using a specific ratio of DMF:DMSO mixed solvent to adjust the crystallization rate). This method effectively suppresses the preferential formation of the three-dimensional tin-based perovskite phase, successfully obtaining a high-quality quasi-two-dimensional deep-red light-emitting thin film with strong quantum confinement effects. The LED device exhibits a main emission peak at approximately 690 nm wavelength, with a full width at half maximum (FWHM) of less than 60 nm and an external quantum efficiency of up to 0.8%. This invention features a simple process with good reproducibility, providing a new solution for the application of quasi-two-dimensional tin-based perovskites in visible light emitting devices, especially in the deep-red / near-red light fields.

[0008] This invention also provides a method for fabricating the above-mentioned environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED device, wherein the fabrication of the perovskite light-emitting layer includes the following steps: S1. Preparation of perovskite precursor solution: Weigh 2-thiophene ethyl ammonium iodide (TEAI), formamidinium iodide (FAI), cesium iodide (CsI), stannous iodide (SnI2), stannous fluoride (SnF2), and additive AD in a molar ratio of (2~3):(0.5~1):(0.5~1):(1~2):0.2:(0.1~0.3), and dissolve them in a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of 1:4. Stir at 55~60℃ for 6~8 hours in an inert atmosphere glove box until completely dissolved to form a transparent solution. After filtration, a precursor solution with a concentration of 0.1~0.2 mol / L is obtained. S2. Preparation of perovskite thin film: The precursor solution obtained in step S1 was spin-coated onto the hole transport layer under an inert atmosphere, followed by annealing, to obtain a quasi-two-dimensional tin-based perovskite thin film with the chemical formula TEA2FASn2I7.

[0009] Further, in step S1, the additive AD is a passivating agent capable of passivating perovskite grain boundary defects without significantly altering its emission wavelength. Preferably, the additive AD is a compound having carboxyl and amino functional groups.

[0010] Furthermore, in step S1, the introduction of cesium iodide (CsI) is used to reduce lattice stress.

[0011] Furthermore, in step S1, the ratio of DMF:DMSO is 1:4. This ratio affects the crystallization kinetics. If the ratio is too high (>1:4), it will easily lead to excessively fast crystallization, a decrease in crystal quality, and the appearance of a three-dimensional perovskite phase with near-infrared luminescence.

[0012] Furthermore, in step S1, when magnetically stirring in an inert atmosphere glove box, the stirring temperature is 60°C and the stirring time is 6 hours.

[0013] Furthermore, the concentration of the precursor solution obtained in step S1 is 0.2 mol / L.

[0014] Furthermore, step S2 specifically includes: S21: The ITO glass substrate is ultrasonically cleaned with deionized water and ethanol for 20 minutes in sequence; then the ITO glass substrate is dried with a nitrogen gun, and the dried ITO glass substrate is treated with a plasma cleaner for 10 minutes to improve the hydrophilicity of the substrate surface. S22: Place the prepared ITO glass substrate on a spin coater, use a pipette to draw a quantitative amount of m-PEDOT:PSS solution and drop it onto the substrate, spin coat at 4000 rpm for 40 seconds, and then transfer the substrate to a 150℃ hot stage for annealing for 15 minutes. S23: In a nitrogen glove box with humidity <1%, use a pipette to take an appropriate amount of the solution prepared in step S1 and spin-coat it on the surface of the m-PEDOT:PSS film at 4000 rpm for 60 s; S24: After spin coating, immediately transfer the substrate to an 80°C hot plate for annealing for 10 minutes to promote the growth and crystallization of perovskite, thereby obtaining a high-quality TEA2FASn2I4 perovskite film.

[0015] Furthermore, in step S22, the m-PEDOT:PSS solution is a PEDOT:PSS solution modified with zinc acetate to ensure that the perovskite layer has good crystal quality.

[0016] Furthermore, in steps S22 and S23, the oxygen content in the nitrogen glove box is <0.1ppm and the humidity is <1%.

[0017] The aforementioned environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED devices can be applied to display devices or biological detection devices.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention is the first to apply a quasi-two-dimensional tin-based perovskite material with the chemical formula TEA2FASn2I7 to the light-emitting layer of a deep red LED, filling the gap in the application of this material system in deep red photoluminescence.

[0019] 2. This invention solves the common problem of the difficulty in forming a quasi-two-dimensional phase in the visible light region of tin-based perovskites by systematic interface engineering and crystallization kinetics control, and obtains deep red light emission with high color purity (half width at half maximum < 60 nm).

[0020] 3. This invention completely eliminates the toxic element lead and uses tin as the B-site cation, resulting in device environmental compatibility that is significantly better than that of lead-based perovskite LEDs.

[0021] 4. This invention employs a one-step spin coating method, which is simple, low-cost, compatible with large-area solution processing technology, and has the potential for industrial production.

[0022] 5. Experimental tests show that the main emission peak of the deep red tin-based two-dimensional perovskite LED prepared by this invention is located at 690 nm (deep red light), and the full width at half maximum (FWHM) is <60 nm. Substrate modification and passivation of defects using passivating agents can effectively improve the crystal quality. The deep red LED device prepared using the quasi-two-dimensional tin-based perovskite material of this invention achieves an external quantum efficiency (EQE) of 0.79%. Attached Figure Description

[0023] Figure 1 This is the photoluminescence spectrum of the quasi-two-dimensional tin-based perovskite deep red perovskite thin film in an embodiment of the present invention.

[0024] Figure 2 The image shows the XRD pattern of the quasi-two-dimensional tin-based perovskite deep red light perovskite thin film in an embodiment of the present invention.

[0025] Figure 3 The images shown are SEM images of the quasi-two-dimensional tin-based perovskite deep red light perovskite films in this embodiment of the invention. (a) shows the film without salicylic acid passivating agent, and (b) shows the film with salicylic acid passivating agent.

[0026] Figure 4 The figures show the performance of the PeLEDSs device containing salicylic acid additive in this embodiment of the invention. Among them, (a) is the EQE-current density curve, (b) is the current density-voltage-brightness curve, and (c) is the EL spectrum.

[0027] Figure 5The figures show the performance of PeLEDs devices with different precursor component ratios in the embodiments of the present invention. Among them, (a) is the EQE-current density curve, (b) is the current density-voltage-brightness curve, and (c) is the EL spectrum.

[0028] Figure 6 The figures show the performance of PeLEDSs devices with different additive contents in the embodiments of the present invention. Among them, (a) is the EQE-current density curve, (b) is the current density-voltage-brightness curve, and (c) is the EL spectrum.

[0029] Figure 7 The figures show the performance of PeLEDSs devices with different contents of zinc acetate modified hole transport layers in the embodiments of the present invention. Among them, (a) is the EQE-current density curve, (b) is the current density-voltage-brightness curve, and (c) is the EL spectrum. Detailed Implementation

[0030] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0031] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0032] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0033] This embodiment provides an environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED device, comprising an anode, a hole transport layer, a perovskite light-emitting layer, an electron transport layer, an electron injection layer, and a cathode stacked sequentially. The perovskite light-emitting layer is a quasi-two-dimensional tin-based perovskite thin film with the chemical formula TEA2FASn2I7, wherein TEA is a 2-thiophene ethylammonium cation. The anode material is indium tin oxide (ITO); the hole transport layer is a zinc acetate-modified poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (m-PEDOT:PSS) thin film; the electron transport layer material is 2,2',2"-(1,3,5-phenyl)-tris(1-phenyl-1H-benzimidazole) (TPBi); the electron injection layer material is lithium fluoride (LiF); and the cathode material is aluminum (Al) or silver (Ag).

[0034] In the above-mentioned method for fabricating an environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED device, the fabrication of the perovskite light-emitting layer includes the following steps: S1. Preparation of perovskite precursor solution: Weigh 2-thiophene ethyl ammonium iodide (TEAI), formamidinium iodide (FAI), cesium iodide (CsI), stannous iodide (SnI2), stannous fluoride (SnF2), and additive AD in a molar ratio of (2~3):(0.5~1):(0.5~1):(1~2):0.2:(0.1~0.3), and dissolve them in a mixed solvent of N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a volume ratio of 1:4. Stir magnetically at 55~60℃ for 6~8 hours in an inert atmosphere glove box until completely dissolved to form a transparent solution. Filter through a 0.22 μm filter membrane to obtain a precursor solution with a concentration of 0.1~0.2 mol / L for later use. S2. Preparation of perovskite thin film: The precursor solution obtained in step S1 was spin-coated onto the hole transport layer under an inert atmosphere, and then annealed at 80°C for 10 minutes to obtain a quasi-two-dimensional tin-based perovskite thin film with the chemical formula TEA2FASn2I7.

[0035] The following description is based on preferred embodiments of the present invention.

[0036] In this embodiment of the invention, all reagents used were of analytical grade. Cesium salts: CsBr (purity ≥99.9%), CsCl (≥99.9%); Tin salts: SnI2 (≥99.9%), SnF2 (≥99.9%); Organic ligands: TEAI (purity ≥99.9%), FAI (purity ≥99.9%); Solvents: N,N-dimethylformamide (DMF, anhydrous grade), dimethyl sulfoxide (DMSO, anhydrous grade), isopropanol (IPA, ≥99.5%); Antisolvent: toluene (anhydrous grade).

[0037] Experimental equipment: magnetic stirrer (temperature control range: 25-150℃); nitrogen glove box (oxygen content <0.1ppm, humidity <1%); spin coater (speed range: 1000-6000 rpm); annealing (temperature control accuracy ±1℃); ultrasonic cleaner. Example 1 This embodiment provides a method for preparing a quasi-two-dimensional tin-based perovskite deep red light perovskite thin film, the steps of which are as follows:

[0038] Preparation of perovskite precursor solution 2-Thiopheneethylammonium iodide (TEAI), formamidinium iodide (FAI), and stannous iodide (SnI2) were dissolved in a 1:4 volume ratio of dimethylformamide (DMF) / dimethyl sulfoxide (DMSO) (8 wt%) at a molar ratio of x:y:z. Then, tin powder was added to the solution to a concentration of 5 mg / mL. -1 The precursor solution was stirred at room temperature for 12 h in a nitrogen atmosphere glove box (H2O < 0.01 ppm, O2 < 0.01 ppm) to obtain a perovskite precursor solution. Before use, it was filtered through a 0.22 μm polytetrafluoroethylene (PTFE) filter. The m-PEDOT:PSS solution was spin-coated onto ITO glass at 5000 rpm for 50 s and annealed at 150 °C for 15 min. The precursor solution was then spin-coated onto an m-PEDOT:PSS film at 7000 rpm for 60 s and annealed at 60 °C for 12 min.

[0039] By adjusting the proportions of 2-thiopheneethylammonium iodide (TEAI), formamidinium iodide (FAI), and stannous iodide (SnI2) in the precursor solution, tin-based perovskite phases with different structures and emission wavelengths can be obtained. For example... Figure 1 As shown, when the molar ratio of 2-thiopheneethylammonium iodide (TEAI), formamidinium iodide (FAI), and stannous iodide (SnI2) is 2:1:1, a quasi-two-dimensional perovskite phase with the molecular formula TEA2FASn2I7 is obtained, with an emission wavelength of 690 nm. When the molar ratio of 2-thiopheneethylammonium iodide (TEAI), formamidinium iodide (FAI), and stannous iodide (SnI2) is 1:1:1, a perovskite phase with an emission wavelength of 780 nm is obtained. When the molar ratio of 2-thiopheneethylammonium iodide (TEAI), formamidinium iodide (FAI), and stannous iodide (SnI2) is 0.5:1:1, a perovskite phase with an emission wavelength of 890 nm is obtained. Figure 2 The XRD pattern of the TEA2FASn2I7 phase prepared for this patent is shown, and compared with the XRD patterns of the previously reported three-dimensional FASnI3 and two-dimensional TEA2SnI4 perovskite phases. Example 2 (1) Preparation of perovskite precursor solution

[0040] 2-Thiopheneethylammonium iodide (PEAI), cesium iodide (CsI), formamidinium iodide (FAI), stannous iodide (SnI2), stannous fluoride (SnF2), and a passivating agent (salicylic acid) were dissolved in a 1:1 volume ratio of dimethylformamide (DMF) / dimethyl sulfoxide (DMSO) mixed solvent (8 wt%) at a molar ratio of 2:0.2:0.8:1:0.1:0.3. Then, tin powder was added to the solution to a concentration of 5 mg / mL. -1The precursor solution was stirred at room temperature for 12 h in a nitrogen atmosphere glove box (H2O < 0.01 ppm, O2 < 0.01 ppm) to obtain a perovskite precursor solution. Before use, the solution was filtered through a 0.22 μm polytetrafluoroethylene (PTEE) filter.

[0041] (2) Preparation of hole transport layer solution Poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT: PSS) was diluted with deionized water at a volume ratio of 1:5. Zinc acetate was added to the above mixture to form a solution containing 10 mg / mL. -1 Zinc acetate hole transport layer solution.

[0042] (3) Device fabrication All LED devices were fabricated on an ITO conductive glass substrate, with a device area of ​​3 mm². 2 The PEDOT:PSS solution was spin-coated onto ITO glass at 5000 rpm for 50 s and annealed at 150 °C for 15 min. The precursor solution was spin-coated onto the PEDOT:PSS film at 7000 rpm for 60 s and annealed at 60 °C for 12 min. Finally, TPBi, LiF and Al layers were deposited by vapor deposition.

[0043] (4) Performance testing Using instruments and equipment such as integrating spheres, optical fibers, spectrometers, digital source meters, and test programs written in LabVIEW software, the performance parameters of LED devices, such as current density-voltage curves (JV curves), external quantum efficiency (EQE), brightness, and electroluminescence spectrum (EL), are tested to evaluate the overall performance of the devices.

[0044] Perovskite thin films were fabricated into devices for performance comparison. Without additives, the perovskite LEDs exhibited low device efficiency (only 0.3%). After adding additives, the EQE of the devices significantly improved. As shown in the figure, the highest EQE (0.456%) was achieved when the additive concentration was 5 mg / ml. The EL emission peak of the devices was at 690 nm.

[0045] Adding suitable additives to the perovskite precursor solution can effectively improve the quality of tin-based two-dimensional perovskite films. For example... Figure 3 As shown, the introduction of the additive salicylic acid makes the perovskite film smoother and improves its crystallization quality. Figure 4 As shown, the optimized device exhibits an electroluminescence spectrum at 690 nm with a maximum external quantum efficiency of 0.79%, which is the highest efficiency among quasi-two-dimensional tin-based perovskite LEDs with deep red light emission. Furthermore, the electroluminescence spectrum maintains good spectral stability under different voltages. Comparative Example 1

[0046] This embodiment provides a method for fabricating a quasi-two-dimensional tin-based perovskite deep red LED, the steps of which are as follows: (1) Preparation of perovskite precursor solution 2-Thiopheneethylammonium iodide (TEAI), cesium iodide + formamidinium iodide (CsI + FAI), stannous iodide (SnI2), stannous fluoride (SnF2), and a passivating agent (salicylic acid) were dissolved in a 1:1 volume ratio of dimethylformamide (DMF) / dimethyl sulfoxide (DMSO) (8 wt%) at a molar ratio of x:y:z:0.1:0.3. Then, tin powder was added to the solution at a concentration of 5 mg / mL. -1 The precursor solution was stirred at room temperature for 12 h in a nitrogen atmosphere glove box (H2O < 0.01 ppm, O2 < 0.01 ppm) to obtain a perovskite precursor solution. Before use, the solution was filtered through a 0.22 μm polytetrafluoroethylene (PTEE) filter.

[0047] (2) Preparation of hole transport layer solution Poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT: PSS) was diluted with deionized water at a volume ratio of 1:5. Zinc acetate was added to the above mixture to form a solution containing 10 mg / mL. -1 Zinc acetate hole transport layer solution.

[0048] (3) Device fabrication All LED devices were fabricated on an ITO conductive glass substrate, with a device area of ​​3 mm². 2 The prepared PEDOT:PSS solution was spin-coated onto ITO glass at 5000 rpm for 50 s and annealed at 150 °C for 15 min. The precursor solution was spin-coated onto the PEDOT:PSS film at 7000 rpm for 60 s and annealed at 60 °C for 12 min. Finally, TPBi, LiF, and Al layers were deposited by vapor deposition. (4) Performance testing Using instruments and equipment such as integrating spheres, optical fibers, spectrometers, digital source meters, and test programs written in LabVIEW software, the performance parameters of LED devices, such as current density-voltage curves (JV curves), external quantum efficiency (EQE), brightness, and electroluminescence spectrum (EL), are tested to evaluate the overall performance of the devices.

[0049] Current conventional methods for preparing quasi-two-dimensional perovskite materials cannot produce quasi-two-dimensional tin-based perovskites with near-infrared luminescence. Figure 5As shown, when the ratio of 2-thiophene ethyl ammonium iodide (TEAI), cesium iodide + formamidinium iodide (CsI+FAI), and tin iodide (SnI2) is 2:1:2, 2:2:2, or 3:1:2, only tin-based perovskite LEDs with near-infrared emission can be obtained. Comparative Example 2

[0050] This embodiment provides a method for fabricating a quasi-two-dimensional tin-based perovskite deep red LED, the steps of which are as follows: (1) Preparation of perovskite precursor solution 2-Thiopheneethylammonium iodide (TEAI), cesium iodide (CsI), formamidinium iodide (FAI), stannous iodide (SnI2), stannous fluoride (SnF2), and a passivating agent (nicotinamide) were dissolved in a 1:1 volume ratio of dimethylformamide (DMF) / dimethyl sulfoxide (DMSO) at a molar ratio of 2:0.2:0.8:1:0.1:0.3 (mass fraction 8 wt%). Then, tin powder was added to the solution to a concentration of 5 mg / mL. -1 The precursor solution was stirred at room temperature for 12 h in a nitrogen atmosphere glove box (H2O < 0.01 ppm, O2 < 0.01 ppm) to obtain a perovskite precursor solution. Before use, the solution was filtered through a 0.22 μm polytetrafluoroethylene (PTEE) filter.

[0051] (2) Preparation of hole transport layer solution Poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT: PSS) was diluted with deionized water at a volume ratio of 1:5. Zinc acetate was added to the above mixture to form a solution containing 10 mg / mL. -1 Zinc acetate hole transport layer solution.

[0052] (3) Device fabrication All LED devices were fabricated on an ITO conductive glass substrate, with a device area of ​​3 mm². 2 The prepared PEDOT:PSS solution was spin-coated onto ITO glass at 5000 rpm for 50 s and annealed at 150 °C for 15 min. The precursor solution was spin-coated onto the PEDOT:PSS film at 7000 rpm for 60 s and annealed at 60 °C for 12 min. Finally, TPBi, LiF, and Al layers were deposited by vapor deposition. (4) Performance testing Using instruments and equipment such as integrating spheres, optical fibers, spectrometers, digital source meters, and test programs written in LabVIEW software, the performance parameters of LED devices, such as current density-voltage curves (JV curves), external quantum efficiency (EQE), brightness, and electroluminescence spectrum (EL), are tested to evaluate the overall performance of the devices.

[0053] Introducing other additives containing amino or carboxyl groups, such as nicotinamide, can also effectively improve the quality of perovskite thin films, but the effect is not as good as that of salicylic acid. Devices fabricated from these perovskite thin films were then compared in performance. Without additives, the device efficiency of perovskite LEDs was low, only 0.3%. After adding additives, the EQE of the devices was significantly improved. Figure 6 As shown, when the additive content is 5 mg / ml, the device has the highest EQE of 0.456%, and the EL emission peak of the device is at 690 nm. Comparative Example 3

[0054] This comparative example is prepared using the same method as the example, corresponding to step (2) of Example 1. The amount of zinc acetate added to the hole transport layer is different in this comparative example.

[0055] Poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) was diluted with deionized water at a volume ratio of 1:5. Zinc acetate was added to the above mixture to form hole transport layer solutions containing different concentrations (concentration range: 0~24 mg / mL) of zinc acetate.

[0056] This invention modifies the hole transport layer by doping with zinc acetate molecules to improve carrier mobility, thereby further enhancing device performance. For example... Figure 7 As shown, the EQE is generally low when zinc acetate is not used for modification. With the addition of zinc acetate, the overall performance of the device gradually increases, and the maximum EQE is reached when the zinc acetate content is 12 mg / ml.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. An environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED device, characterized in that, It includes an anode, a hole transport layer, a perovskite light-emitting layer, an electron transport layer, an electron injection layer, and a cathode, which are stacked in sequence; the perovskite light-emitting layer is a quasi-two-dimensional tin-based perovskite thin film with the chemical formula TEA2FASn2I7, wherein TEA is a 2-thiophene ethylammonium cation.

2. The environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED device according to claim 1, characterized in that, The anode material is indium tin oxide; the hole transport layer is a zinc acetate-modified poly(3,4-ethylenedioxythiophene):polystyrene sulfonate film; the electron transport layer material is 2,2',2"-(1,3,5-phenyl)-tris(1-phenyl-1H-benzimidazole); the electron injection layer material is lithium fluoride; and the cathode material is aluminum or silver.

3. A method for fabricating an environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED device as described in claim 1 or 2, characterized in that, The preparation of the perovskite light-emitting layer includes the following steps: S1. Preparation of perovskite precursor solution: Weigh 2-thiophene ethylammonium iodide, formamidinium iodide, cesium iodide, stannous iodide, stannous fluoride, and additive AD in a molar ratio of (2~3):(0.5~1):(0.5~1):(1~2):0.2:(0.1~0.3), and dissolve them in a mixed solvent of N,N-dimethylformamide and dimethyl sulfoxide in a volume ratio of 1:

4. Stir at 55~60℃ for 6~8 hours in an inert atmosphere glove box until completely dissolved to form a transparent solution. After filtration, a precursor solution with a concentration of 0.1~0.2 mol / L is obtained. S2. Preparation of perovskite thin film: The precursor solution obtained in step S1 was spin-coated onto the hole transport layer under an inert atmosphere, followed by annealing, to obtain a quasi-two-dimensional tin-based perovskite thin film with the chemical formula TEA2FASn2I7.

4. The method for fabricating the environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED device according to claim 3, characterized in that, In step S1, the additive AD is a passivating agent that can passivate perovskite grain boundary defects without significantly changing its emission wavelength.

5. The method for fabricating the environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED device according to claim 4, characterized in that, The additive AD is a compound with carboxyl and amino functional groups.

6. The method for fabricating the environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED device according to claim 3, characterized in that, In step S1, when stirring in an inert atmosphere glove box, the stirring temperature is 60°C and the stirring time is 6 hours.

7. The method for fabricating the environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED device according to claim 3, characterized in that, Step S2 specifically includes: S21: The ITO glass substrate is ultrasonically cleaned with deionized water and ethanol for 20 minutes in sequence; then the ITO glass substrate is dried with a nitrogen gun, and the dried ITO glass substrate is treated with a plasma cleaner for 10 minutes to improve the hydrophilicity of the substrate surface. S22: Place the prepared ITO glass substrate on a spin coater, use a pipette to draw a quantitative amount of m-PEDOT:PSS solution and drop it onto the substrate, spin coat at 4000 rpm for 40 seconds, and then transfer the substrate to a 150℃ hot stage for annealing for 15 minutes. S23: In a nitrogen glove box with humidity <1%, use a pipette to take an appropriate amount of the solution prepared in step S1 and spin-coat it on the surface of the m-PEDOT:PSS film at 4000 rpm for 60 s; S24: After spin coating, immediately transfer the substrate to an 80°C hot plate for annealing for 10 minutes to promote the growth and crystallization of perovskite, thereby obtaining a high-quality TEA2FASn2I4 perovskite film.

8. The method for fabricating the environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED device according to claim 7, characterized in that, In step S22, the m-PEDOT:PSS solution is a PEDOT:PSS solution modified with zinc acetate to ensure that the perovskite layer has good crystal quality.

9. The method for fabricating the environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED device according to claim 7, characterized in that, In steps S22 and S23, the oxygen content in the nitrogen glove box is <0.1ppm and the humidity is <1%.

10. An application of the environmentally friendly quasi-two-dimensional tin-based perovskite deep red LED device as described in claim 1 or 2, characterized in that, It is used in display devices or biological detection devices.

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