Sulfaguanidine modified inorganic tin-based perovskite light-emitting diode and preparation method thereof

Abstract

The invention discloses a sulfaguanidine modified inorganic tin-based perovskite light-emitting diode and a preparation method thereof, and belongs to the field of luminescent material preparation, the preparation method comprises the following steps: preparing a perovskite precursor solution which comprises cesium iodide, stannous iodide, sulfaguanidine and an organic solvent; applying the perovskite precursor solution to a substrate to form a wet film; carrying out annealing treatment on the wet film so as to form a perovskite light-emitting layer containing CsSnI3 perovskite and sulfaguanidine; a hole transport layer is formed on an anode conductive substrate, and a perovskite light-emitting layer is adopted on the hole transport layer; and sequentially forming an electron transport layer, an electron injection layer and a cathode electrode on the perovskite light-emitting layer. The process is simple and suitable for popularization and application.

Description

Technical Field

[0001] This invention relates to the field of luminescent material preparation, and in particular to a sulfanilamide guanidine-modified inorganic tin-based perovskite light-emitting diode and its preparation method. Background Technology

[0002] Low-cost, solution-processable, all-inorganic tin-based perovskite materials have shown broad application prospects in the field of light-emitting diodes (LEDs) due to their environmental friendliness, tunable bandgap, and high carrier mobility. Compared to traditional lead-based perovskites, tin-based materials have lower toxicity and their degradation products are harmless to the environment, making them more in line with sustainable development requirements. Therefore, they have become one of the hot topics in optoelectronic materials research in recent years. Especially in light-emitting devices, tin-based perovskites can achieve efficient near-infrared emission, making them suitable for various applications such as biosensing, night vision, and optical communication.

[0003] However, all-inorganic CsSnI3 materials still face significant challenges in practical device fabrication. On the one hand, divalent tin ions are extremely unstable in air and easily oxidize to tetravalent tin, leading to a large number of vacancy defects in the film, severely reducing luminescence efficiency and device stability. On the other hand, the material itself has strong p-type characteristics, resulting in a severe imbalance between hole and electron injection, further limiting radiative recombination efficiency. Although some studies have attempted to improve performance through additive regulation and interface modification, most strategies still struggle to simultaneously achieve efficient defect passivation and carrier balance regulation, resulting in device efficiencies far lower than lead-based perovskites, hindering its advancement from the laboratory to practical applications. Summary of the Invention

[0004] One of the objectives of this invention is to provide a method for fabricating inorganic tin-based perovskite light-emitting diodes modified with sulfanilamide guanidine, in order to solve the problem in the prior art that it is difficult to simultaneously achieve efficient defect passivation and carrier balance control, resulting in device efficiency that is much lower than that of lead-based perovskites.

[0005] This invention is achieved through the following technical solution: a method for fabricating an inorganic tin-based perovskite light-emitting diode modified with sulfanilamide guanidine, comprising the following steps: a) preparing a perovskite precursor solution, wherein the solution contains cesium iodide, stannous iodide, sulfanilamide guanidine, and an organic solvent, wherein the organic solvent is dimethyl sulfoxide; b) applying the perovskite precursor solution onto a substrate to form a wet film; c) annealing the wet film to form a perovskite light-emitting layer comprising CsSnI3 perovskite and sulfanilamide guanidine; d) forming a hole transport layer on an anode conductive substrate, wherein the hole transport layer comprises PEDOT:PSS and PSS:Na; e) employing a perovskite light-emitting layer on the hole transport layer; f) sequentially forming an electron transport layer, an electron injection layer, and a cathode electrode on the perovskite light-emitting layer.

[0006] Furthermore, the perovskite precursor solution provided in step a) also contains at least one stabilizer selected from stannous chloride and tin powder.

[0007] Furthermore, the molar ratio of cesium iodide, stannous iodide, stannous chloride, and sulfanilamide guanidine in the perovskite precursor solution is 1:1:0.1:0.018~0.019.

[0008] Furthermore, between step e) and step f), a post-treatment layer is applied to the perovskite luminescent layer, the post-treatment layer containing SPPO13 solvent at a concentration of 4 mg / mL.

[0009] Further, step b) includes: applying the perovskite precursor solution onto the substrate using a spin coating method, and adding an anti-solvent to it during the spin coating process.

[0010] Furthermore, the antisolvent is chlorobenzene.

[0011] Furthermore, the annealing treatment in step c) is performed at a temperature of 100℃~120℃ for 5~15 minutes.

[0012] Further, in step f), the electron transport layer comprises B3PYMPM; in step f), the electron injection layer is LiF; in step f), the cathode electrode is Al; and each layer in step f) is formed by vacuum evaporation.

[0013] In another aspect, the present invention provides a sulfanilamide-modified inorganic tin-based perovskite light-emitting diode, the light-emitting diode comprising: an anode; a cathode; and a perovskite light-emitting layer comprising CsSnI3 perovskite and sulfanilamide-modified perovskite light-emitting diode disposed between the anode and the cathode, prepared according to the method for preparing sulfanilamide-modified inorganic tin-based perovskite light-emitting diodes as described above.

[0014] Furthermore, the structure of the perovskite light-emitting diode is as follows: an anode conductive substrate / a hole transport layer containing PEDOT:PSS and PSS:Na / the perovskite light-emitting layer / a post-processing layer containing SPPO13 / an electron transport layer containing B3PYMPM / a LiF electron injection layer / an Al cathode.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0016] 1. This invention effectively inhibits Sn 2+ Oxidizes and passivates defects: through the S=O group in the sulfanilamide guanidine molecule and Sn 2+ Formation of strong coordination bonds, and guanidinyl groups and I -The dual effect of hydrogen bonding significantly inhibits the formation of tin and iodine vacancies, reduces the trap state density of the thin film, and improves the stability of the material.

[0017] 2. This invention improves carrier injection balance: The introduction of sulfanilamide guanidine optimizes the morphology of the perovskite film, forming a uniformly distributed spherical crystal structure, increasing the contact area with the electron transport layer, and at the same time adjusting the energy level structure of the material, promoting electron injection and achieving a more balanced carrier recombination.

[0018] 3. This invention significantly improves device performance: The perovskite light-emitting diode based on sulfanilamide guanidine modification achieves an external quantum efficiency of 8.1%, exhibits good electroluminescence characteristics at 948 nm, and achieves high efficiency at 20 mA cm⁻¹. -2 Under constant current, the device has a working life of 45.8 hours, which is significantly better than the unmodified control device. Moreover, the process is simple and suitable for widespread application. The additive can be directly dissolved in the precursor solution, which is fully compatible with existing solution processing technology. No complicated post-processing steps are required. The preparation method is simple and has good reproducibility. Attached Figure Description

[0019] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings:

[0020] Figure 1 This is a structural diagram of the light-emitting diode provided in Embodiment 1 of the present invention.

[0021] Figure 2 The chemical structure diagram of sulfaguanidine provided in Example 1 of the present invention is shown.

[0022] Figure 3 The diagram shows the structure of a light-emitting diode provided as a comparative example of the present invention.

[0023] Figure 4 The brightness-voltage curve is provided as a comparative example of the present invention.

[0024] Figure 5 The current density-voltage curve is provided as a comparative example of the present invention.

[0025] Figure 6 The external quantum efficiency-current density curve is provided as a comparative example of the present invention.

[0026] Figure 7 The electroluminescence spectrum is provided as a comparative example of the present invention. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated herein by reference to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail. The terms “comprising,” “including,” “having,” “containing,” etc., as used herein are open-ended terms, meaning that they include but are not limited to. Unless the context clearly indicates otherwise, the expressions “a” and “an” as used herein include plural references. It should be noted that “first,” “second,” etc., are used merely for convenience of description and distinction and should not be construed as indicating or implying relative importance. The term “about” as used herein indicates a range of ±20% of the following numerical value. In some embodiments, the term “about” indicates a range of ±10% of the following numerical value. In some embodiments, the term “about” indicates a range of ±5% of the following numerical value.

[0029] Example

[0030] In this embodiment, a sulfanilamide guanidine-modified inorganic tin-based perovskite light-emitting diode and its preparation method are described.

[0031] like Figure 1 As shown, the structure of the light-emitting diode in this embodiment, from bottom to top, consists of: an anode ITO conductive substrate, a hole transport layer, a CsSnI3 perovskite light-emitting layer modified with sulfanilamide guanidine, a post-treatment layer, an electron transport layer, an electron injection layer, and a cathode Al electrode.

[0032] The specific fabrication process of this light-emitting diode is as follows:

[0033] (1) Preparation of perovskite precursor solution

[0034] In a nitrogen-filled glove box, 1 mL of dimethyl sulfoxide (DMSO) was used as the solvent, and 65 mg of cesium iodide (CsI), 93 mg of stannous iodide (SnI2), 4.7 mg of stannous chloride (SnCl2), and 5 mg of tin powder were added sequentially. The mixture was magnetically stirred at room temperature for 12 hours to allow it to fully dissolve and react. The resulting solution was then filtered through a 0.1 μm polytetrafluoroethylene (PTFE) filter to remove unreacted tin powder and any impurities. 1 mg of sulfaguanidine (SG) powder was added to the clear filtrate. The chemical structure and ball-and-stick model of sulfaguanidine are shown below. Figure 2 As shown. Continue magnetic stirring for at least 6 hours until sulfanilamide is completely dissolved, finally obtaining a homogeneous and transparent sulfanilamide-modified CsSnI3 perovskite precursor solution with a concentration of 0.25 mol / L, for later use.

[0035] (2) Preparation of hole transport layer solution

[0036] Take a 50 mg / mL sodium polystyrene sulfonate (PSS:Na) aqueous solution and mix it with a poly(3,4-ethylenedioxythiophene):polystyrene sulfonic acid (PEDOT:PSS) aqueous solution at a volume ratio of 1.2:1. Vortex the mixture for 5 minutes to ensure homogeneity and obtain the hole transport layer solution.

[0037] (3) Preparation of post-treatment solution

[0038] 1,3-bis[3,5-bis(pyridin-3-yl)phenyl]benzene (SPPO13) was dissolved in chlorobenzene solvent to prepare a solution with a concentration of 4 mg / mL, which was used as the post-treatment solution.

[0039] (4) Substrate cleaning

[0040] An ITO glass substrate with dimensions of 1.6 cm × 1.6 cm and a sheet resistance of 150 Ω / m² was sequentially placed in glass cleaning agent, deionized water, and anhydrous ethanol, and ultrasonically cleaned for 15 minutes in each solution. After cleaning, it was dried with high-purity nitrogen gas and then placed in a plasma cleaner for 5 minutes to further clean it and improve its surface hydrophilicity.

[0041] (5) Preparation of hole transport layer

[0042] In an air glove box, the hole transport layer solution prepared in step (2) was spin-coated onto the ITO substrate treated in step (4). The spin-coating program was set to rotate at 4000 rpm for 40 seconds. After spin-coating, the sample with the wet film was placed on a hot stage at 150°C for annealing for 15 minutes to remove the solvent and form a uniform and dense hole transport layer film.

[0043] (6) Preparation of perovskite luminescent layer

[0044] The substrate with the hole transport layer was transferred to a nitrogen glove box. Using a micropipette, 30 μL of the sulfanilamide-modified CsSnI3 precursor solution prepared in step (1) was dynamically spin-coated onto the hole transport layer at 4000 rpm. At 40 seconds after spin-coating began, 500 μL of chlorobenzene was rapidly added dropwise to the center of the rotating substrate as an antisolvent to promote rapid and uniform nucleation and growth of perovskite grains. Immediately after spin-coating, the sample was transferred to a 110°C hot plate for annealing for 10 minutes. After annealing, the sample was allowed to cool naturally in the glove box to obtain a high-quality sulfanilamide-modified CsSnI3 perovskite film.

[0045] (7) Preparation of post-treatment layer

[0046] After the perovskite film has completely cooled, take 50 μL of the SPPO13 chlorobenzene solution prepared in step (3) and spin-coat it onto the surface of the perovskite film at a speed of 6000 rpm for 30 seconds to form a post-treatment layer.

[0047] (8) Fabrication of electronic functional layer and cathode

[0048] The samples processed in the above steps are transferred to an ultra-high vacuum evaporation chamber, ensuring that the chamber vacuum level is better than 5 × 10⁻⁶. -4 Pa. A 50 nm thick layer of 4,5',6,7'-tetratetra(biphenyl-3-yl)-2,2'-bipyridine (B3PYMPM) was sequentially deposited on the post-treatment layer via thermal evaporation as an electron transport layer, a 2 nm thick layer of lithium fluoride (LiF) as an electron injection layer, and an 80 nm thick layer of metallic aluminum (Al) as a cathode. The effective light-emitting area of ​​the device was limited to 0.04 mm² by shadow mask control. 2 This completes the fabrication of the light-emitting diode described in this embodiment.

[0049] Comparative Example

[0050] To verify the beneficial effects of the technical solution of the present invention, a comparative example was set up.

[0051] Figure 3The structural diagram of the light-emitting diode of this comparative example is shown. The fabrication process, materials used, and parameters of each layer of the comparative device are exactly the same as those of the example. The only difference is that no sulfanilamide (SG) additive is added when preparing the perovskite precursor solution in step (1). That is, CsI, SnI2, SnCl2 and tin powder are dissolved in DMSO, stirred and filtered to directly obtain an unmodified CsSnI3 precursor solution (0.25 mol / L), which is then used for the subsequent preparation of the perovskite light-emitting layer.

[0052] Technical effectiveness verification:

[0053] The photoelectric performance of the light-emitting diode devices prepared in the above embodiments and comparative examples was tested, and the results are as follows: Figures 3-7 As shown. Among them, Figure 4 This is a brightness-voltage curve. Figure 5 This is a current density-voltage curve. Figure 6 The graph shows the external quantum efficiency (EQE) versus current density. Figure 7 This is an electroluminescence (EL) spectrum. From Figure 4 and Figure 5 As can be seen, compared with the comparative device, the device prepared in this embodiment of the invention exhibits significantly lower leakage current and higher luminance under the same driving voltage. This preliminarily indicates that the introduction of sulfanilamide guanidine improves the quality of the perovskite film, reduces non-radiative recombination centers, and thus enhances the charge injection and recombination efficiency of the device.

[0054] Reference Figure 6 The external quantum efficiency (EQE)-current density curves show that the maximum EQE of the comparative device is only about 4.8%, while the maximum EQE of the device in this embodiment reaches 8.1%, representing a performance improvement of nearly 70%. This result fully demonstrates that sulfanilamide guanidine, as an additive, can greatly improve the performance of all-inorganic tin-based perovskite light-emitting diodes, achieving unexpected technical effects.

[0055] Reference Figure 7 The electroluminescence (EL) spectra of the devices in both the example and the comparative examples show that the emission peaks are located at approximately 950 nm, with no shift in peak position. However, the emission intensity of the device in the example is significantly higher than that of the comparative device. This indicates that the role of sulfanilamide guanidine molecules is to effectively passivate defects (such as tin vacancies) at the grain boundaries or surface of the perovskite thin film, suppressing nonradiative recombination and thus significantly improving radiative recombination efficiency, rather than altering the emission bandgap of the perovskite material itself by entering the lattice.

[0056] In summary, this invention successfully solves the problems of numerous defects and unbalanced carrier injection in tin-based perovskite films by introducing sulfanilamide guanidine as a novel and effective additive into the CsSnI3 perovskite precursor solution. It has produced an all-inorganic tin-based perovskite light-emitting diode with excellent photoelectric performance and significantly improved external quantum efficiency. It has the advantages of simple process, low cost and significant effect, and shows great potential for practical application.

[0057] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating an inorganic tin-based perovskite light-emitting diode modified with sulfanilamide guanidine, characterized in that, The preparation method includes: a) Prepare a perovskite precursor solution comprising cesium iodide, stannous iodide, sulfanilamide guanidine, and an organic solvent. The organic solvent is dimethyl sulfoxide; b) Apply the perovskite precursor solution onto the substrate to form a wet film; c) Anneal the wet film to form a perovskite luminescent layer comprising CsSnI3 perovskite and sulfanilamide guanidine; d) Forming a hole transport layer on an anodic conductive substrate, The hole transport layer comprises PEDOT:PSS and PSS:Na; e) A perovskite light-emitting layer is used on the hole transport layer; f) An electron transport layer, an electron injection layer, and a cathode electrode are sequentially formed on the perovskite light-emitting layer.

2. The method for preparing sulfanilamide guanidine-modified inorganic tin-based perovskite light-emitting diodes according to claim 1, characterized in that, The perovskite precursor solution provided in step a) further includes at least one stabilizer selected from stannous chloride and tin powder.

3. The method for preparing an inorganic tin-based perovskite light-emitting diode modified with sulfanilamide guanidine according to claim 1 or 2, characterized in that, The molar ratio of cesium iodide, stannous iodide, stannous chloride, and sulfanilamide guanidine in the perovskite precursor solution is: 1 ：1 ：0.1 ：0.018~0.019。 4. The method for preparing the sulfanilamide guanidine-modified inorganic tin-based perovskite light-emitting diode according to claim 1, characterized in that, Between step e) and step f), a post-treatment layer is applied to the perovskite luminescent layer. The post-treatment layer contains SPPO13 solvent at a concentration of 4 mg / mL.

5. The method for preparing sulfanilamide guanidine-modified inorganic tin-based perovskite light-emitting diodes according to claim 1, characterized in that, Step b) includes: applying the perovskite precursor solution onto the substrate using a spin coating method, and adding an anti-solvent during the spin coating process.

6. The method for preparing an inorganic tin-based perovskite light-emitting diode modified with sulfanilamide guanidine according to claim 5, characterized in that, The antisolvent is chlorobenzene.

7. The method for preparing an inorganic tin-based perovskite light-emitting diode modified with sulfanilamide guanidine according to claim 1, characterized in that, The annealing temperature in step c) is 100℃~120℃. The time is 5 to 15 minutes.

8. The method for preparing sulfanilamide guanidine-modified inorganic tin-based perovskite light-emitting diodes according to claim 1, characterized in that, In step f), the electron transport layer comprises B3PYMPM; In step f), the electron injection layer is LiF; In step f), the cathode electrode is Al; Each layer in step f) is formed by vacuum evaporation.

9. A sulfanilamide guanidine-modified inorganic tin-based perovskite light-emitting diode, characterized in that, The light-emitting diode includes: anode; cathode; And a perovskite luminescent layer comprising CsSnI3 perovskite and sulfanilamide guanidine, disposed between the anode and the cathode and prepared according to the preparation method of any one of claims 1 to 7.

10. The sulfanilamide guanidine-modified inorganic tin-based perovskite light-emitting diode according to claim 9, characterized in that, The structure of the perovskite light-emitting diode is as follows: Anode conductive substrate / Hole transport layer containing PEDOT:PSS and PSS:Na / Perovskite light-emitting layer / Post-treatment layer containing SPPO13 / Electron transport layer containing B3PYMPM / LiF electron injection layer / Al cathode.

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