Preparation method and application of quasi-two-dimensional perovskite film based on all-green solvent organic-inorganic hybrid

Abstract

The application discloses a preparation method and application of an organic-inorganic hybrid quasi-two-dimensional perovskite film based on a full green solvent and belongs to the technical field of perovskite device preparation. In the preparation method of the organic-inorganic hybrid quasi-two-dimensional perovskite film based on the full green solvent, a green solvent triethylene glycol is selected as a solvent to replace traditional solvents such as N, N dimethylformamide (DMF) and dimethyl sulfoxide (DMSO), and a green solvent n-butyl acetate is selected as an anti-solvent to promote the crystallization growth of perovskite, so that the solvent toxicity problem in the processing of the organic-inorganic hybrid quasi-two-dimensional perovskite film is solved. Based on the full green solvent system, the organic-inorganic hybrid quasi-two-dimensional perovskite film with compactness and good surface morphology can be prepared, and the application has potential application value in the field of perovskite device processing.

Description

Technical Field

[0001] This invention relates to the technical field of perovskite device fabrication, and in particular to a method for preparing and applying an organic-inorganic hybrid quasi-two-dimensional perovskite thin film based on an all-green solvent. Background Technology

[0002] Organic-inorganic hybrid quasi-two-dimensional perovskites possess excellent optical properties, and organic-inorganic hybrid quasi-two-dimensional perovskite light-emitting diodes (LEDs) based on them are expected to be used in lighting and display fields, attracting widespread attention from academia and industry. Preparing high-quality organic-inorganic hybrid quasi-two-dimensional perovskite thin films is a prerequisite for obtaining high-efficiency quasi-two-dimensional perovskite LEDs. Quasi-two-dimensional perovskite thin films are mostly prepared using a one-step method, which involves dissolving three precursors in solvents DMSO or DMF to prepare a precursor solution of a certain concentration. Then, the organic-inorganic hybrid quasi-two-dimensional perovskite thin film is prepared by spin coating or blade coating combined with anti-solvent treatment, annealing, and other processes. However, in the preparation of the precursor solution, to ensure the solubility of PbX2, solvents such as DMSO or DMF, which have potential hazards to human health and the environment, are often used. At the same time, toxic and harmful solvents such as chlorobenzene and toluene are often used as anti-solvents to control the crystallization process of the perovskite. The extensive use of such solvents poses a significant threat to the health of workers and environmental safety, hindering the large-scale processing and application of perovskite light-emitting diodes (LEDs) in the future. Therefore, there is an urgent need for a greener solvent to dissolve perovskite precursors, combined with a green antisolvent, to prepare quasi-two-dimensional perovskite thin films. This is of great significance to the development of organic-inorganic hybrid quasi-two-dimensional perovskite LEDs. Summary of the Invention

[0003] In view of this, the technical problem to be solved by the present invention is to provide a method for preparing organic-inorganic hybrid quasi-two-dimensional perovskite thin films based on a completely green solvent and its application. The preparation method solves the solvent toxicity problem in the preparation of organic-inorganic hybrid perovskite thin films in the prior art, and when applied to the preparation of light-emitting diodes, it exhibits ideal external quantum efficiency.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] This invention provides a method for preparing organic-inorganic hybrid quasi-two-dimensional perovskite thin films based on an all-green solvent, comprising the following steps:

[0006] 1) Dissolve the organic-inorganic hybrid quasi-two-dimensional perovskite precursor in triethylene glycol to obtain a precursor solution;

[0007] 2) A hole transport layer is coated on the substrate surface, and then the precursor solution obtained in step 1) is spin-coated on the hole transport layer surface. During the spin-coating process, n-butyl acetate, the anti-solvent, is dropped onto the liquid film surface. Then, annealing is performed to prepare an organic-inorganic hybrid quasi-two-dimensional perovskite thin film.

[0008] In the above preparation method, the organic-inorganic hybrid quasi-two-dimensional perovskite film precursor is dissolved in triethylene glycol, and the stirring temperature is preferably 40°C.

[0009] Preferably, in step 1), the concentration of the precursor solution is 0.2–0.4 mol / L. -1 .

[0010] Preferably, the organic-inorganic hybrid quasi-two-dimensional perovskite precursor in step 1) includes formamidinium bromide, lead bromide, and phenylethylamine bromide.

[0011] Preferably, the molar ratio of formamidinium bromide, lead bromide, and phenylethylamine bromide is (0.6-1.4):1:(0.4-0.8).

[0012] In some specific embodiments of the present invention, the molar ratio of formamidine bromide, lead bromide and phenylethylamine bromide is preferably 1:1:0.4.

[0013] The substrate in step 2) above is preferably a transparent conductive indium tin oxide.

[0014] In this invention, after cleaning the transparent conductive indium tin oxide, a hole transport layer is spin-coated onto the surface of the transparent conductive indium tin oxide.

[0015] Preferably, in step 2), the hole transport layer is selected from poly(3,4-vinyldioxythiophene)-poly(styrene sulfonate), i.e. (PEDOT:PSS).

[0016] Adding the antisolvent n-butyl acetate promotes the crystallization growth of perovskite films.

[0017] Preferably, in step 2), the volume ratio of the antisolvent n-butyl acetate to triethylene glycol is (1-1.5):1; more preferably (1.1-1.4):1; and even more preferably 1.25:1.

[0018] Preferably, in step 2), the antisolvent n-butyl acetate is added at 70 to 90 seconds after the start of spin coating of the precursor solution; more preferably, at 80 seconds.

[0019] Finally, the organic-inorganic hybrid quasi-two-dimensional perovskite film was annealed to prepare an organic-inorganic hybrid quasi-two-dimensional perovskite film with high crystallinity and good surface morphology.

[0020] Preferably, the annealing temperature in step 2) of this invention is 60°C to 90°C; more preferably, it is 70°C to 80°C. In some specific embodiments of this invention, the annealing temperature is preferably 80°C.

[0021] Preferably, the annealing time in step 2) is 5 to 15 minutes; more preferably, it is 5 to 10 minutes. In some specific embodiments of the present invention, the annealing time is preferably 5 minutes.

[0022] The present invention also provides the application of the above-mentioned method for preparing organic-inorganic hybrid quasi-two-dimensional perovskite thin films based on all-green solvents in the fabrication of perovskite devices.

[0023] Preferably, the perovskite device is selected from light-emitting diodes.

[0024] When the above-mentioned method for preparing organic-inorganic hybrid quasi-two-dimensional perovskite thin films is applied to the preparation of light-emitting diodes (LEDs), the resulting LEDs exhibit ideal external quantum efficiency.

[0025] When the molar ratio of formamidinium bromide, lead bromide, and phenylethylamine bromide in the organic-inorganic hybrid quasi-two-dimensional perovskite thin film is 1:1:0.4, the external quantum efficiency of the light-emitting diode is optimal.

[0026] The specific fabrication method of the light-emitting diode includes:

[0027] An electron transport layer is vacuum-deposited on the surface of the organic-inorganic hybrid quasi-two-dimensional perovskite thin film prepared by the above preparation method. Then, a cathode modification layer LiF and a cathode Al are vacuum-deposited on the electron transport layer to prepare an organic-inorganic hybrid quasi-two-dimensional perovskite light-emitting diode.

[0028] Compared with existing technologies, the method for preparing organic-inorganic hybrid quasi-two-dimensional perovskite thin films based on all-green solvents provided by this invention uses triethylene glycol as the solvent for the perovskite precursor and n-butyl acetate as the anti-solvent, thereby promoting the crystallization and growth of perovskite to obtain a dense and uniform perovskite thin film. Furthermore, the prepared organic-inorganic hybrid quasi-two-dimensional perovskite thin film exhibits ideal external quantum efficiency when applied to light-emitting diodes (LEDs). The preparation method described in this invention solves the solvent toxicity problem in the preparation of organic-inorganic hybrid perovskite thin films in existing technologies, and has great potential application value not only in the field of LEDs but also in fields such as perovskite solar cells and photodetectors. Attached Figure Description

[0029] Figure 1 The X-ray diffraction pattern of the organic-inorganic hybrid quasi-two-dimensional perovskite thin film in Example 1;

[0030] Figure 2This is a scanning electron microscope image of the organic-inorganic hybrid quasi-two-dimensional perovskite thin film in Example 1;

[0031] Figure 3 The diagram shows the device structure of the organic-inorganic hybrid quasi-two-dimensional perovskite light-emitting diodes in Example 1 and Comparative Example 5.

[0032] Figure 4 The voltage-current density-brightness curve of the organic-inorganic hybrid quasi-two-dimensional perovskite light-emitting diode in Example 1 is shown.

[0033] Figure 5 The image shows a scanning electron microscope image of the organic-inorganic hybrid quasi-two-dimensional perovskite thin film in Comparative Example 5.

[0034] Figure 6 The voltage-current density-brightness curves of the organic-inorganic hybrid quasi-two-dimensional perovskite light-emitting diode in Comparative Example 5 are shown. Detailed Implementation

[0035] To further illustrate the present invention, the preparation method and application of the organic-inorganic hybrid quasi-two-dimensional perovskite thin film based on an all-green solvent provided by the present invention will be described in detail below with reference to the embodiments. The organic-inorganic hybrid quasi-two-dimensional perovskite thin film prepared by the method is applied to a light-emitting diode and has an ideal external quantum efficiency.

[0036] Example 1

[0037] (1) Preparation of organic-inorganic hybrid quasi-two-dimensional perovskite precursor solution: The molar ratio of the three components is FABr:PbBr2:PEABr=1:1:0.4 (specifically, the molar concentration of FABr is 0.2 mol / L). -1 PbBr2 is 0.2 mol / L -1 PEABr is 0.08 mol / L -1 25.0 mg FABr, 73.4 mg PbBr2, and 16.2 mg PEABr were dissolved together in 1 mL of triethylene glycol and stirred at 40 °C to obtain 0.2 mol / L. -1 The precursor solution.

[0038] (2) Clean and dry the substrate. Taking ITO (indium tin oxide) glass substrate as an example, clean the glass substrate (3cm×3cm) with cleaning solution, then sonicate it with deionized water, acetone and isopropanol for 10 minutes each, and then put it in an oven at 130℃ to dry.

[0039] (3) Preparation of hole transport layer: The above substrate was placed on the suction cup of a spin coater, and an aqueous solution of PEDOT:PSS (PEDOT is a polymer of EDOT (3,4-ethylenedioxythiophene monomer) and PSS is polystyrene sulfonate) was uniformly coated onto the substrate through a 0.45 μm filter head to form a film by spin coating at a speed of 5000 rpm for 2 min. Then, it was annealed at 140 °C for 15 min to obtain the ITO / PEDOT:PSS substrate.

[0040] (4) Preparation of quasi-two-dimensional perovskite thin film layer: Transfer the ITO / PEDOT:PSS substrate prepared in step (3) to the glove box. After the substrate cools down, place the substrate on the suction cup of the spin coater and drop 200 μL of the prepared quasi-two-dimensional perovskite precursor solution onto the substrate. Spin coat at 5000 rpm for 2 min. Add 250 μL of green anti-solvent n-butyl acetate at 80 s after the start of spin coating. After spin coating, place the substrate on the hot stage and anneal at 80 ℃ for 5 min to improve the crystallinity of the perovskite and obtain the substrate with thin film layer (ITO / PEDOT:PSS / Perovskite).

[0041] (5) Fabrication of electron transport layer and cathode: The substrate with the perovskite thin film layer was transferred to a vacuum evaporation machine, and a vacuum was drawn. When the pressure reached 7×10⁻⁶, the electron transport layer and cathode were prepared. -7 At the Pascal time, the electron transport layer material is first deposited by evaporation. In this example, 1,3,5-tris[(3-pyridyl)-3-phenyl]benzene (TmPyPb) is used. Then, 1 nm thick LiF and 100 nm thick Al are deposited as cathodes.

[0042] Figure 1 The X-ray diffraction pattern of the organic-inorganic hybrid quasi-two-dimensional perovskite thin film in Example 1 is shown below. Figure 1 The diffraction peaks of the crystal planes (100), (110), and (200) corresponding to FAPbBr3 can be seen, proving that organic-inorganic hybrid quasi-two-dimensional perovskite thin films were successfully prepared using Example 1.

[0043] Figure 2 These are scanning electron microscope images of the organic-inorganic hybrid quasi-two-dimensional perovskite thin film in Example 1. Figure 2 As can be seen from the example, Example 1 prepared a dense, fully covered organic-inorganic hybrid quasi-two-dimensional perovskite film.

[0044] like Figure 3 As shown, the final organic-inorganic hybrid quasi-two-dimensional perovskite light-emitting diode has the following device structure: ITO / PEDOT:PSS / Perovskite / TmPyPb / LiF / Al. The effective light-emitting area of ​​this device is 0.14 cm².2 The perovskite layer in the figure is an organic-inorganic hybrid quasi-two-dimensional perovskite thin film prepared by the method for preparing organic-inorganic hybrid quasi-two-dimensional perovskite thin films based on all-green solvents described in this invention.

[0045] The prepared organic-inorganic hybrid quasi-two-dimensional perovskite light-emitting diodes (LEDs) were subjected to performance testing. Current density-voltage and luminance-voltage data were measured in a nitrogen glove box using a Keithley 2400 source meter and a calibrated silicon photodiode. The voltage range was 0–9 V, the test step size was 0.2 V, and the scan rate was 0.2 V / s. The electroluminescence spectrum was recorded using a CS2000A spectroradiometer. The external quantum efficiency was calculated based on the current density, luminance, and electroluminescence spectrum, assuming the LED was a Lambertian light source.

[0046] Its current density-brightness-voltage characteristic curve is as follows: Figure 4 As shown in Table 1, the device's maximum luminance and maximum external quantum efficiency are 61916 cd / m². -2 and 12.89%.

[0047] Comparative Examples 1-4

[0048] Compared to Example 1, in Comparative Examples 1-4, ethanol, isopropanol, ethylene glycol, or 1,4-butanediol were used instead of triethylene glycol, and the composition and proportion of the perovskite precursor were the same as in Example 1. The results showed that the solvents described in Comparative Examples 1-4 could not be used to prepare perovskite precursor solutions, nor could quasi-two-dimensional perovskite films be obtained. This indicates that the organic-inorganic hybrid quasi-two-dimensional perovskite film exhibits selectivity for green alcohol solvents.

[0049] Comparative Example 5

[0050] This comparative example provides a method for preparing an organic-inorganic hybrid quasi-two-dimensional perovskite light-emitting diode based on the green solvent triethylene glycol and the non-green antisolvent chlorobenzene. The preparation process of this device is the same as in Example 1, except that chlorobenzene is used as the antisolvent in this comparative example; all other conditions remain the same as in Example 1. The final result is an organic-inorganic hybrid quasi-two-dimensional perovskite light-emitting diode, whose device structure (as shown in the image)... Figure 3 The composition is ITO / PEDOT:PSS / Perovskite / TmPyPb / LiF / Al, and the effective light-emitting area of ​​this device is 0.14 cm². -2 .

[0051] Figure 5 These are scanning electron microscope images of the organic-inorganic hybrid quasi-two-dimensional perovskite thin film in Comparative Example 5. Figure 5 As can be seen, the surface of the perovskite film prepared using chlorobenzene as an antisolvent is discontinuous.

[0052] Table 1 Comparison of device performance parameters of quasi-two-dimensional perovskite light-emitting diodes prepared in Example 1 and Comparative Example 5

[0053] Example 1 3.0 55.4 12.89 61916 533 Comparative Example 5 3.0 29.0 6.74 24502 535

[0054] Note: V turn-on (V) is the power-on voltage, CE max (cd A -1 ) represents the maximum current efficiency EQE max (%) represents the maximum external quantum efficiency, L max (cd m -2 ) represents the maximum brightness, λ EL (nm) represents the electroluminescence wavelength.

[0055] In summary, the method for preparing organic-inorganic hybrid quasi-two-dimensional perovskite thin films based on all-green solvents described in this invention uses triethylene glycol as the solvent for the quasi-two-dimensional perovskite precursor and n-butyl acetate as the anti-solvent. The resulting organic-inorganic hybrid quasi-two-dimensional perovskite thin film has a continuous and smoother surface. When applied to the preparation of quasi-two-dimensional perovskite light-emitting diodes, organic-inorganic hybrid quasi-two-dimensional perovskite light-emitting diodes with higher brightness and better external quantum efficiency can be obtained.

[0056] The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing an organic-inorganic hybrid quasi-two-dimensional perovskite thin film based on an all-green solvent, characterized in that, Includes the following steps: 1) Dissolve the organic-inorganic hybrid quasi-two-dimensional perovskite precursor in triethylene glycol to obtain a precursor solution; 2) A hole transport layer is coated on the substrate surface, and then the precursor solution obtained in step 1) is spin-coated on the hole transport layer surface. During the spin-coating process, n-butyl acetate, the anti-solvent, is dropped onto the liquid film surface. Then, annealing is performed to prepare an organic-inorganic hybrid quasi-two-dimensional perovskite thin film.

2. The method for preparing organic-inorganic hybrid quasi-two-dimensional perovskite thin films based on an all-green solvent according to claim 1, characterized in that, In step 1), the concentration of the precursor solution is 0.2–0.4 mol / L. -1 .

3. The method for preparing organic-inorganic hybrid quasi-two-dimensional perovskite thin films based on an all-green solvent according to claim 1, characterized in that, The organic-inorganic hybrid quasi-two-dimensional perovskite precursor in step 1) includes formamidinium bromide, lead bromide, and phenylethylamine bromide.

4. The method for preparing organic-inorganic hybrid quasi-two-dimensional perovskite thin films based on an all-green solvent according to claim 1, characterized in that, The hole transport layer in step 2) is selected from poly(3,4-vinyldioxythiophene)-poly(styrene sulfonate).

5. The method for preparing organic-inorganic hybrid quasi-two-dimensional perovskite thin films based on an all-green solvent according to claim 1, characterized in that, In step 2), the volume ratio of the antisolvent n-butyl acetate to triethylene glycol is (1-1.5):

1.

6. The method for preparing organic-inorganic hybrid quasi-two-dimensional perovskite thin films based on an all-green solvent according to claim 1, characterized in that, In step 2), the antisolvent n-butyl acetate is added at 70-90 seconds after the start of spin coating of the precursor solution.

7. The method for preparing organic-inorganic hybrid quasi-two-dimensional perovskite thin films based on an all-green solvent according to claim 1, characterized in that, The annealing temperature in step 2) is 60℃~90℃.

8. The method for preparing organic-inorganic hybrid quasi-two-dimensional perovskite thin films based on an all-green solvent according to claim 1, characterized in that, The annealing time in step 2) is 5 to 15 minutes.

9. The application of the method for preparing organic-inorganic hybrid quasi-two-dimensional perovskite thin films based on all-green solvents as described in any one of claims 1 to 8 in the fabrication of perovskite devices.

10. The application according to claim 9, characterized in that, The perovskite device is selected from light-emitting diodes.

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