A method for preparing inorganic perovskite heterojunction nanorods by using nanowires and application thereof to optoelectronic devices

Abstract

The application belongs to the technical field of perovskite nanocrystal synthesis, and particularly relates to a method for preparing high-polarization inorganic perovskite heterojunction nanorods by using nanowires and application of the method to optoelectronic devices. The method comprises the following steps: (1) mixing a monovalent cation compound, a halide BX2, a ligand, a weakly polar or non-polar organic solvent, and an acidic aqueous solution, continuously ultrasonicating or stirring at room temperature, and reacting; after standing, mixing the upper solution with the weakly polar or non-polar solvent, adding the halide, and continuously stirring and reacting, so as to obtain a colloidal solution of inorganic perovskite heterojunction nanorods; centrifuging, discarding the supernatant, and drying in a vacuum drying box, so as to obtain perovskite nanorod powder. The prepared nanorods have high quantum efficiency, the intermediate process can be monitored, so that the growth process can be more accurately tracked, and the length-diameter ratio of the nanorods can be finally accurately controlled.

Description

Technical Field

[0001] This application belongs to the field of perovskite nanocrystal synthesis technology, specifically relating to a method for preparing inorganic perovskite heterojunction nanorods using nanowires and their application in optoelectronic devices. Background Technology

[0002] In recent years, perovskite materials have been widely used in optoelectronic devices due to their excellent properties. However, the instability of organic-inorganic hybrid perovskites has limited their development, leading to the increasing interest in all-inorganic perovskites. All-inorganic perovskite nanomaterials are easy to prepare and have tunable morphologies, including not only common nanobulks but also spherical quantum dots, nanowires, nanorods, and nanosheets. The optoelectronic properties of perovskite nanocrystals are closely related to their morphology and structure; therefore, in-depth research on the morphology control of all-inorganic perovskite nanocrystals is crucial.

[0003] Compared to perovskite nanocrystals with other morphologies or structures, heterojunction perovskite nanorods not only possess advantages such as high absorption coefficient, high fluorescence quantum yield, and tunable bandgap, but also exhibit high carrier mobility and high linear polarization light emission characteristics. This makes them stand out in fields such as liquid crystal displays (LCDs), light-emitting diodes (LEDs), laser processing, dynamic displays, and biomedical imaging. Currently used injection synthesis methods often result in excessively rapid nucleation and growth rates, making it difficult to effectively control the morphology and size of perovskite nanocrystals, thus limiting their applications.

[0004] Yongkai Wang et.(Advanced Functional MaterialsVolume 31,Issue 222011251; Reversible Transformation between CsPbBr3 Perovskite Nanowires andNanorods with Polarized Optoelectronic Properties discloses a method for synthesizing ultrafine CsPbX3 perovskite nanowires with a diameter of 2-3 nm. It also discloses that dispersing nanowires colloidally in cyclohexane transforms them into nanorods, the length and diameter of which can be controlled by concentration and time. Dispersing these nanorods in the synthesis supernatant allows them to revert back into nanowires. This method requires first preparing cesium oleate and lead oleate solutions at high temperature (120°C), then mixing these solutions to obtain a colloidal nanowire solution. Before the nanowires are converted into nanorods, centrifugation and redispersion are necessary to obtain a stable colloidal nanowire solution. The entire process involves numerous steps and requires stringent synthesis conditions. Furthermore, centrifugation and redispersion of the colloidal nanowire solution cause significant changes in the surface states of the nanowires, introducing more uncontrollable variables and ultimately making it impossible to precisely control the formation of nanorods. Summary of the Invention

[0005] To address the current problems in the production of inorganic perovskite nanorods, and after fully understanding the nanorod growth mechanism, this invention provides a method for preparing heterojunction nanorods from inorganic perovskite nanowires using a secondary growth approach. This method is simple, introduces few variables, is low-cost, and produces nanorods with high quantum efficiency and high polarization. It also allows for monitoring of intermediate processes, enabling more accurate tracking of the growth process and ultimately precise control of the nanorod's aspect ratio.

[0006] The technical solution of this application is as follows:

[0007] A method for preparing inorganic perovskite heterostructure nanorods using nanowires includes the following steps:

[0008] (1) Inorganic perovskite nanowires can be prepared by mixing a monovalent cationic compound, halide BX2, ligand, weakly polar or nonpolar organic solvent, and acidic aqueous solution, and reacting by continuous sonication or stirring at room temperature.

[0009] (2) After the mixture in step (1) is allowed to stand, the upper layer solution is taken and mixed with the weakly polar or non-polar solvent in step (1), a halide is added, and the mixture is stirred and reacted to obtain a colloidal solution of inorganic perovskite heterostructure nanorods.

[0010] (3) Centrifuge the colloidal solution from step (2), discard the clear liquid, and dry it in a vacuum drying oven to obtain perovskite nanorod powder.

[0011] Preferably, the halide in step (2) includes at least one of sodium halide, cesium halide, zinc halide, erbium halide, bismuth halide, silver halide, neodymium halide and cobalt halide.

[0012] Preferably, the monovalent cationic compound in step (1) is one or more of cesium carbonate, rubidium carbonate, cesium acetate, rubidium acetate, cesium oleate, cesium bromide, and rubidium bromide; and / or

[0013] The halide BX2, wherein B is one of lead, tin or manganese, and X is one of chlorine, bromine, iodine or any combination of two; and / or

[0014] The ligand is at least one selected from oleic acid, oleylamine, phosphatidylcholine, tri-n-octylphosphine oxide, triisooctyl phosphate, 2-acrylamido-2-methylpropanesulfonic acid, citric acid or citrate, polyethylene glycol with a carboxyl or amino terminal group, dimethylaminoethyl acrylate, polyvinylpyrrolidone, stearic acid, octadecylamine, and 1-butyl-1-methylpiperidine tetrafluoroborate; and / or

[0015] The weakly polar or nonpolar organic solvent is one of ethyl acetate, 1,4-dioxane, methyl formate, methyl acetate, and tetrahydrofuran, and the monovalent cationic compound and halide BX2 are only slightly soluble or insoluble in it.

[0016] Preferably, in step 1, the molar ratio of the monovalent cation to the halide BX2 is 1:1 to 1:2; and / or

[0017] The reaction temperature is 20℃~90℃; and / or

[0018] The acidic aqueous solution is one of hydrochloric acid, sulfuric acid, phosphoric acid, hydrobromic acid, hydroiodic acid, or an aqueous solution of an organic acid; and / or

[0019] In step 1, the volume ratio of the acidic aqueous solution to the nonpolar solvent is 2% to 5%; and / or

[0020] The nanowires are longer than 600 nm and have a width of 2 nm–6 nm.

[0021] Preferably, the supernatant taken in step (2) should be taken 15 minutes after step (1), at which time the reaction solution has a bright blue or cyan-blue fluorescence under ultraviolet light.

[0022] Furthermore, in step (2), the molar ratio of the added halide to the perovskite nanowires in the supernatant is 0.05–0.5; and / or

[0023] In step (2), the nanowires gradually transform into nanorods, with heterostructures at both ends of the nanorods. The width of the nanorods is 2nm–6nm, and the length of the nanorods is 10nm–200nm; and / or

[0024] The reaction temperature is 20℃~90℃.

[0025] Increasing the temperature can accelerate the transformation process, and the halide added in step (2) grows faster at both ends of the nanorod and gradually transforms into a dumbbell shape.

[0026] Furthermore, in step (2), the amount of solvent added to reaction flask B is 1%-2000% of the amount taken from reaction flask A.

[0027] Another objective of this invention is to protect the inorganic perovskite heterostructure nanorods prepared by the above method.

[0028] Another object of the present invention is to protect the application of the above-mentioned inorganic perovskite heterojunction nanorods in lasers or polarization light sources.

[0029] Furthermore, the inorganic perovskite heterojunction nanorods described above can achieve a quantum efficiency of over 90% and a luminescence polarization degree of 0.86.

[0030] Beneficial effects of the present invention

[0031] (1) This invention utilizes inorganic perovskite nanowires to prepare heterojunction nanorods, which is simple, precise, and low-cost.

[0032] (2) The all-inorganic perovskite heterostructure nanorods prepared by this invention can achieve a uniform morphology, good stability, quantum efficiency of over 90%, and luminescence polarization degree of 0.86.

[0033] (3) The inorganic perovskite heterojunction nanorods synthesized in this invention can be separated, purified and dried to obtain a large number of powder samples with high yield and easy storage and transportation. Attached Figure Description

[0034] Figure 1 This is a TEM image of the CsPbBr3 nanowires prepared in step (1) of Example 1;

[0035] Figure 2 This is a photograph of the CsPbBr3 heterojunction nanorod colloidal solution prepared in Example 1 under a UV lamp.

[0036] Figure 3 TEM image of the CsPbBr3 heterostructure nanorods prepared in Example 1;

[0037] Figure 4 TEM image of the CsPbBr3 heterostructure nanorods prepared in Example 2;

[0038] Figure 5 This is a TEM image of the CsPbCl3 heterojunction nanorods prepared in Example 3. Detailed Implementation

[0039] The present invention will be described in detail below with reference to the embodiments, but the present invention is not limited to the following embodiments.

[0040] Example 1

[0041] A method for preparing inorganic perovskite heterostructure nanorods using nanowires, characterized by comprising the following steps:

[0042] (1) In reaction flask A, 0.0525g CsBr, 0.13g PbBr2, 315μL oleic acid, 315μL oleylamine, 5mL 1,4-dioxane, and 75μL hydrochloric acid aqueous solution are mixed and stirred continuously at room temperature for 45min to obtain a colloidal solution of CsPbBr3 nanowires. The concentration of the hydrochloric acid aqueous solution is: 1mL of 37% concentrated hydrochloric acid mixed with 100mL of water, i.e., 0.12mol / mL.

[0043] (2) Add 1 mL of 1,4-dioxane to reaction flask B, and stir continuously at a reaction temperature of 35°C.

[0044] (3) After letting reaction flask A stand for 5 minutes, take 2 mL of the solution from reaction flask A and 8 × 10⁸ ml of the solution. -5 Add mol of neodymium bromide to reaction flask B and stir continuously for 45 min;

[0045] (4) After centrifuging the reaction solution in the reaction flask at 10000r / min for 8min and discarding the clear liquid, dry it in a vacuum drying oven at 50℃ for 7 hours to obtain CsPbBr3 heterojunction nanorod powder with uniform size and aspect ratio of 25:1.

[0046] Example 2

[0047] A method for preparing inorganic perovskite heterostructure nanorods using nanowires, characterized by comprising the following steps:

[0048] (1) In reaction flask A, 0.0525g CsBr, 0.13g PbBr2, 315μL oleic acid, 315μL oleylamine, 5mL 1,4-dioxane, and 75μL hydrochloric acid aqueous solution are mixed and stirred continuously at room temperature for 45min to obtain a colloidal solution of CsPbBr3 nanowires. The concentration of the hydrochloric acid aqueous solution is: 2mL of 37% concentrated hydrochloric acid mixed with 100mL of water, i.e., 0.24mol / mL.

[0049] (2) Add 1 mL of 1,4-dioxane to reaction flask B, and stir continuously at a reaction temperature of 35°C.

[0050] (3) After letting reaction flask A stand for 5 minutes, take 2 mL of the solution from reaction flask A and 8 × 10⁸ ml of the solution. -5 Add 1 mol of erbium bromide to reaction flask B and stir continuously for 90 min;

[0051] (4) After centrifuging the reaction solution in the reaction flask at 10000r / min for 8min and discarding the clear liquid, dry it in a vacuum drying oven at 50℃ for 7 hours to obtain CsPbBr3 heterojunction nanorod powder with uniform size and an aspect ratio of 30:1.

[0052] Example 3

[0053] A method for preparing inorganic perovskite heterostructure nanorods using nanowires, characterized by comprising the following steps:

[0054] (1) In reaction flask A, 0.0525g CsCl, 0.12g PbCl2, 315μL oleic acid, 315μL oleylamine, 5mL 1,4-dioxane, and 75μL hydrochloric acid aqueous solution are mixed and stirred continuously at room temperature for 45min to obtain a colloidal solution of CsPbCl3 nanowires. The concentration of the hydrochloric acid aqueous solution is: 1mL of 37% concentrated hydrochloric acid mixed with 100mL of water, i.e., 0.12mol / mL.

[0055] (2) Add 1 mL of 1,4-dioxane to reaction flask B, and stir continuously at a reaction temperature of 35°C.

[0056] (3) After letting reaction flask A stand for 5 minutes, take 2 mL of the solution from reaction flask A and 8 × 10⁸ ml of the solution. -5 Add mol of zinc chloride to reaction flask B and stir continuously for 90 minutes;

[0057] (4) After centrifuging the reaction solution in the reaction flask at 10000r / min for 8min and discarding the clear liquid, dry it in a vacuum drying oven at 50℃ for 7 hours to obtain CsPbCl3 heterojunction nanorod powder with uniform size and an aspect ratio of 8:1.

[0058] Example 4

[0059] A method for preparing inorganic perovskite heterostructure nanorods using nanowires, characterized by comprising the following steps:

[0060] (1) In reaction flask A, mix 0.0525g CsBr, 0.13g PbBr2, 315μL oleic acid, 315μL oleylamine, 5mL 1,4-dioxane, and 75μL citric acid aqueous solution (concentration 0.2mol / mL) and stir continuously at room temperature for 45min to obtain a colloidal solution of CsPbBr3 nanowires;

[0061] (2) Add 1 mL of 1,4-dioxane to reaction flask B, and stir continuously at a reaction temperature of 35°C.

[0062] (3) Let reaction flask A stand for 5 min, take 2 mL of the solution in reaction flask A and 0.017 g of CsBr and add it to reaction flask B, and stir continuously for 90 min;

[0063] (4) After centrifuging the reaction liquid in the reaction flask at 10000r / min for 8min and discarding the clear liquid, the mixture is dried in a vacuum drying oven at 50℃ for 7 hours to obtain heterojunction nanorod powder with uniform size and an aspect ratio of 27:1. The nanorods have Cs4PbBr6 crystal phase at both ends and CsPbBr3 crystal phase in the middle.

[0064] Example 5

[0065] A method for preparing inorganic perovskite heterostructure nanorods using nanowires, characterized by comprising the following steps:

[0066] (1) In reaction flask A, 0.0525g CsBr, 0.13g PbBr2, 315μL oleic acid, 315μL oleylamine, 5mL 1,4-dioxane, and 75μL hydrochloric acid aqueous solution are mixed and stirred continuously at 45℃ for 20min to obtain a colloidal solution of CsPbBr3 nanowires. The concentration of the hydrochloric acid aqueous solution is: 1mL of 37% concentrated hydrochloric acid mixed with 100mL of water, i.e., 0.12mol / mL.

[0067] (2) Add 1 mL of 1,4-dioxane to reaction flask B, and stir continuously at a reaction temperature of 45°C.

[0068] (3) After letting reaction flask A stand for 5 minutes, take 2 mL of the solution from reaction flask A and 8 × 10⁸ ml of the solution. -5 1 mol of cobalt bromide was added to reaction flask B and stirred continuously for 45 min;

[0069] (4) After centrifuging the reaction solution in the reaction flask at 10000r / min for 8min and discarding the clear liquid, dry it in a vacuum drying oven at 50℃ for 7 hours to obtain CsPbBr3 heterojunction nanorod powder with uniform size and aspect ratio of 12:1.

[0070] Example 6

[0071] A method for preparing inorganic perovskite heterostructure nanorods using nanowires, characterized by comprising the following steps:

[0072] (1) In reaction flask A, 0.0525g CsBr, 0.13g PbBr2, 0.38g TOPO, 5mL 1,4-dioxane, and 75μL hydrochloric acid aqueous solution are mixed and stirred continuously at 45℃ for 20min to obtain a colloidal solution of CsPbBr3 nanowires. The concentration of the hydrochloric acid aqueous solution is: 1mL of 37% concentrated hydrochloric acid mixed with 100mL of water, i.e., 0.12mol / mL.

[0073] (2) Add 2 mL of 1,4-dioxane to reaction flask B, and stir continuously at a reaction temperature of 45°C.

[0074] (3) After letting reaction flask A stand for 5 minutes, take 2 mL of the solution from reaction flask A and 8 × 10⁸ ml of the solution. -5 Add mol of neodymium bromide to reaction flask B and stir continuously for 45 min;

[0075] (4) After centrifuging the reaction solution in the reaction flask at 10000r / min for 8min and discarding the clear liquid, dry it in a vacuum drying oven at 50℃ for 7 hours to obtain CsPbBr3 heterojunction nanorod powder with uniform size and aspect ratio of 8:1.

[0076] Comparative Example 1

[0077] Step (3) Do not add 8×10 -5 Add mol of neodymium bromide to reaction flask B, and follow the same procedure as in Example 1. The final product is CsPbBr3 nanorods, which are non-heterojunction structures with a polarization degree of 0.58.

[0078] Comparative Example 2

[0079] Step (3) Do not add 8×10 -5 1 mol of neodymium bromide was added to reaction flask B along with PbBr2. The rest of the process was the same as in Example 1. The PbBr2 added in step (3) had no effect on the reaction. This was consistent with step (3) where 8 × 10 mol of neodymium bromide was not added. -5 The results obtained with mol of neodymium bromide were the same, that is, the final result was the same as that of Comparative Example 1.

[0080] Implementation Results Example

[0081] The properties of the CsPbBr3 heterojunction nanorod powders obtained in Examples 1-6 and Comparative Examples 1 and 2 were determined as follows:

[0082] Example 1 98 0.86 Example 2 97 0.84 Example 3 92 0.8 Example 4 98 0.86 Example 5 96 0.83 Example 6 91 0.8 Comparative Example 1 93 0.58 Comparative Example 2 93 0.58

Claims

1. A method for preparing highly polarized inorganic perovskite heterostructure nanorods using nanowires, characterized in that, Includes the following steps: (1) Mix a monovalent cationic compound, halide BX2, ligand, weakly polar or nonpolar organic solvent, and acidic aqueous solution, and react continuously under room temperature conditions with ultrasonication or stirring at a temperature of 20℃~90℃ to obtain inorganic perovskite nanowires. (2) After the mixture in step (1) is allowed to stand, the upper layer solution is mixed with the weakly polar or non-polar solvent in step (1), a halide is added, and the mixture is stirred and reacted at a temperature of 20℃~90℃ to obtain a colloidal solution of inorganic perovskite heterostructure nanorods. (3) Centrifuge the colloidal solution from step (2), discard the clear liquid, and dry it in a vacuum drying oven to obtain perovskite nanorod powder; The halide mentioned in step (2) includes at least one of sodium halide, cesium halide, zinc halide, erbium halide, bismuth halide, silver halide, neodymium halide and cobalt halide; The monovalent cationic compound mentioned in step (1) is one or more of cesium carbonate, rubidium carbonate, cesium acetate, rubidium acetate, cesium oleate, cesium bromide, and rubidium bromide; The halide BX2 is wherein B is one of lead, tin or manganese, and X is one of chlorine, bromine or iodine or any combination of two of them.

2. The method for preparing high-polarization inorganic perovskite heterostructure nanorods using nanowires according to claim 1, characterized in that, The ligand is at least one selected from oleic acid, oleylamine, phosphatidylcholine, tri-n-octylphosphine oxide, triisooctyl phosphate, 2-acrylamido-2-methylpropanesulfonic acid, citric acid or citrate, polyethylene glycol with a carboxyl or amino terminal group, dimethylaminoethyl acrylate, polyvinylpyrrolidone, stearic acid, octadecylamine, and 1-butyl-1-methylpiperidine tetrafluoroborate; and / or The weakly polar or nonpolar organic solvent is one of ethyl acetate, 1,4-dioxane, methyl formate, methyl acetate, and tetrahydrofuran, and the monovalent cationic compound and halide BX2 are only slightly soluble or insoluble in it.

3. The method for preparing high-polarization inorganic perovskite heterostructure nanorods using nanowires according to claim 1 or 2, characterized in that, In step 1, the molar ratio of the monovalent cation compound and the halide BX2 is 1:1 to 1:2; and / or The acidic aqueous solution is one of hydrochloric acid, sulfuric acid, phosphoric acid, hydrobromic acid, hydroiodic acid, or an aqueous solution of an organic acid; and / or In step 1, the volume ratio of the acidic aqueous solution, weakly polar or nonpolar organic solvent is 2% to 5%; and / or The nanowires are longer than 600 nm and have a width of 2 nm to 6 nm.

4. The method for preparing high-polarization inorganic perovskite heterostructure nanorods using nanowires according to claim 1, characterized in that, The supernatant solution to be taken in step (2) should be taken 15 minutes after step (1), at which time the reaction solution has a bright blue or cyan-blue fluorescence under ultraviolet light.

5. The method for preparing high-polarization inorganic perovskite heterostructure nanorods using nanowires according to claim 1, characterized in that, In step (2), the molar ratio of the added halide to the perovskite nanowires in the supernatant is 0.05–0.5; and / or In step (2), the nanowires gradually transform into nanorods, with heterostructures at both ends of the nanorods. The width of the nanorods is 2 nm to 6 nm, and the length of the nanorods is 10 nm to 200 nm.

6. Inorganic perovskite heterostructure nanorods prepared by the method according to any one of claims 1 to 5.

7. The application of the inorganic perovskite heterojunction nanorods according to claim 6 in lasers or polarization light sources.

8. The application according to claim 7, characterized in that, The inorganic perovskite heterojunction nanorods described above have a quantum efficiency of over 90% and an emission polarization degree of 0.86.

Images