Surface-modified metal halide perovskite nanorod composite luminescent material and preparation method thereof

Abstract

This invention discloses a surface-modified metal halide perovskite nanorod composite luminescent material and its preparation method, comprising metal halide perovskite nanorods and a surface copolymer, wherein the surface copolymer is a sulfonic acid-terminated poly(4-vinylpyridine)-poly(trifluoroethyl methacrylate) block copolymer (P4VP-PTFEMA). This invention uses poly(4-vinylpyridine) (P4VP) and poly(trifluoroethyl methacrylate) (PTFEMA) to form a star-shaped 21-arm block copolymer under the initiation of cyclodextrin. After end-group sulfonation treatment, it can stably bind to the surface of metal halide perovskite nanorods, significantly improving the stability of metal halide perovskite nanorods in extreme environments such as ambient temperature, high temperature, and pure polar solvent environments, maintaining a high level of fluorescence intensity. Furthermore, the preparation process is simple, applicable to perovskite nanorods of different types and sizes, uses inexpensive raw materials, and the process is easily scaled up.

Description

TECHNICAL FIELD

[0001] The present application relates to a composite luminescent material and a preparation method thereof, in particular to a surface-modified metal halide perovskite nanorod composite luminescent material and a preparation method thereof. BACKGROUND

[0002] Metal halide perovskite nanorods, as a new one-dimensional semiconductor nanomaterial, have attracted extensive attention due to their excellent photoelectric properties. They not only inherit the inherent high light absorption coefficient, high defect tolerance, tunable band gap, and excellent charge transport capacity of perovskite materials, but also exhibit great application potential in the fields of polarized luminescence, low threshold laser, and high-performance photodetectors due to their unique anisotropic structure. This one-dimensional confinement effect also brings higher carrier separation efficiency and carrier lifetime, making it an ideal building block for the next generation of nano-optoelectronic devices.

[0003] However, perovskite nanorods, especially high-performance lead halide perovskite, face a severe challenge in their industrialization: insufficient stability. The crystal compound structure of this material makes it extremely sensitive to environmental factors such as moisture, oxygen, light, and heat. When exposed to air, its crystal structure is prone to degradation, leading to fluorescence quenching and deterioration of photoelectric performance. This inherent instability seriously restricts its long-term application and service life in optoelectronic devices.

[0004] To solve this bottleneck problem, researchers have explored various strategies including polymer encapsulation to improve the stability of perovskite nanorods. The literature paper Regulating Charge Carrier Dynamics in Stable Perovskite Nanorods for Photo-Induced Atom Transfer Radical Polymerization proposes a strategy of using PS-grafted lead cesium bromide (CsPbBr3), but does not explore the stability of nanorods under extreme conditions such as high temperature and pure polar solvent environment. SUMMARY

[0005] The purpose of the present application is to provide a surface-modified metal halide perovskite nanorod composite luminescent material that is stable in both normal temperature atmospheric environment and extreme environment, and to provide a preparation method of the surface-modified metal halide perovskite nanorod composite luminescent material.

[0006] Technical solution: The surface modified metal halide perovskite nanorod composite luminescent material of the application comprises a metal halide perovskite nanorod and a surface copolymer, and the surface copolymer is a block copolymer of sulfonic acid group terminated poly-4-vinylpyridine-poly-trifluoroethyl methacrylate.

[0007] The metal halide perovskite nanorod is a bromine lead cesium perovskite nanorod (CsPbBr3), which has a high ray absorption coefficient and excellent photoelectric performance.

[0008] The block copolymer of poly-4-vinylpyridine-poly-trifluoroethyl methacrylate is a star-shaped 21-arm block copolymer of poly-4-vinylpyridine-poly-trifluoroethyl methacrylate (P4VP-PTFEMA), which has a unique star structure and can form multiple grafting sites on the surface of the perovskite nanorod to improve the grafting density. 2+ The pyridine groups in the P4VP segment can form a firm coordination bond with the uncoordinated Pb 2+ of the perovskite surface, effectively passivate the defects of Pb

[0009] The mass percentage of the metal halide perovskite nanorod is 17.5-25wt%, the mass percentage of poly-4-vinylpyridine is 25-27.5wt%, and the mass percentage of poly-trifluoroethyl methacrylate is 50-55wt%.

[0010] Specifically, the microstructure of the nanorod material is that the star-shaped 21-arm P4VP-PTFEMA block copolymer is grafted on the surface of the CsPbBr3 perovskite nanorod as a hydrophobic protective layer, and the PTFEMA is close to the perovskite nanorod side, and the P4VP is away from the perovskite nanorod side, wherein the average width of the CsPbBr3 perovskite nanorod is about 10.0-15.0nm, and the length can be adjusted to 100-300nm; the molecular weight of the PTFEMA is 5000-15000kg / mol, and the molecular weight of the P4VP is 2500-7500kg / mol.

[0011] The preparation method of the surface modified metal halide perovskite nanorod composite luminescent material comprises the following steps:

[0012] (1) Preparation of a block copolymer of star-shaped 21-arm poly(4-vinylpyridine-poly(trifluoroethyl methacrylate)) (P4VP-PTFEMA);

[0013] (2) Add a sulfonating agent to the aforementioned star-shaped 21-arm poly(4-vinylpyridine-poly(trifluoroethyl methacrylate)) block copolymer and perform end-group sulfonation treatment to obtain a sulfonic acid-terminated poly(4-vinylpyridine-poly(trifluoroethyl methacrylate)) block copolymer.

[0014] (3) Prepare metal halide perovskite nanorods co-capped with octylamine / oleylamine, and graft the aforementioned sulfonic acid-capped star-shaped 21-arm poly(4-vinylpyridine-poly(trifluoroethyl methacrylate)) block copolymer onto the surface of the metal halide perovskite nanorods co-capped with octylamine / oleylamine.

[0015] In step (1), the preparation of the star-shaped 21-arm poly(4-vinylpyridine)-poly(trifluoroethyl methacrylate) block copolymer includes the following steps: after functionalizing cyclodextrin (CD), it first undergoes a polymerization reaction with 4-vinylpyridine (4VP) under the action of an initiator. The resulting polymerization product then undergoes a polymerization reaction with trifluoroethyl methacrylate (TFEMA) under the action of an initiator, so that the finally prepared surface-modified metal halide perovskite nanorod composite luminescent material forms a surface coating layer with PTFEMA as the side close to the perovskite nanorod and P4VP as the side away from the perovskite nanorod. The highly hydrophobic PTFEMA can directly cover the surface of the metal halide perovskite nanorod, so that it can better isolate water, oxygen and pure polar solvents and improve stability.

[0016] Preferably, the functionalization treatment includes thiolation of cyclodextrin with 2-(dodecyltrithiocarbonate)-2-methylpropionic acid (DDMAT) to give it a -SH group, which can act as a reversible addition-fragmentation chain transfer polymerization (RAFT) agent to initiate the subsequent generation of a star-shaped 21-arm P4VP-PTFEMA block copolymer.

[0017] Preferably, the initiator is azobisisobutyronitrile (AIBN), used to initiate the polymerization of TFEMA and 4VP respectively. The molecular weight of the polymer is determined by the polymerization reaction time; the longer the reaction time, the larger the molecular weight of the polymer.

[0018] Preferably, in each polymerization step, the molar ratio of monomer, initiator and RAFT reagent is 100~500:0.2:1.

[0019] Preferably, the cyclodextrin is β-cyclodextrin with a suitable internal cavity size and a unique 21-arm structure that allows the star-shaped block copolymer to be stably bound to the surface of the perovskite nanorods, achieving an excellent coating effect.

[0020] In step (2), the sulfonation reagent is m-chloroperoxybenzoic acid, which introduces 21 sulfonic acid groups into the P4VP-PTFEMA end group of the star-shaped 21-arm. The sulfonic acid groups have a strong binding affinity on the surface of the metal halide perovskite nanorods and will not undergo UV-induced dissociation. They also work together with the pyridine groups in the P4VP repeating unit to achieve strong binding on the surface of the perovskite nanorods, effectively passivating the surface defects of the metal halide perovskite nanorods and improving their fluorescence retention rate in complex environments.

[0021] In step (3), the metal halide perovskite nanorods co-capped with octylamine / oleylamine are prepared by hot injection method. The prepared perovskite nanorods have uniform size, high crystallinity and excellent optical properties. The octylamine / oleylamine co-capping treatment enables them to undergo ligand exchange reaction with the star-shaped 21-arm poly(4-vinylpyridine-poly(trifluoroethyl methacrylate)) capped with sulfonic acid to form a coating layer.

[0022] Preferably, the hot injection method includes the following steps: cesium carbonate (Cs2CO3), oleic acid, and octadecene are mixed in a mass ratio of 1:3~5:15~30 and then heated to degas, and reacted at high temperature to obtain a cesium salt precursor; lead bromide (PbBr2), octylamine, oleylamine, and octadecene are mixed in a mass ratio of 1:5~10:10~20:20~50 and then heated to degas, reacted at high temperature, and then rapidly injected into the aforementioned cesium salt precursor; after the reaction is completed, the mixture is cooled to room temperature, and n-hexane is used as a poor solvent to precipitate the precipitate, which is the octylamine / oleylamine co-terminated metal halide perovskite nanorod.

[0023] In step (3), the grafting includes dissolving the sulfonic acid-terminated star-shaped 21-arm poly(4-vinylpyridine-poly(trifluoroethyl methacrylate)) block copolymer in a solvent, adding the aforementioned octylamine / oleylamine co-terminated metal halide perovskite nanorods, mixing them to allow a ligand exchange reaction to occur, so that the sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymer is grafted onto the surface of the metal halide perovskite nanorods, thus coating them.

[0024] Preferably, the mixing is ultrasonic dispersion, which can accelerate the ligand exchange reaction and make the reaction more complete. After ultrasonic dispersion, ethyl acetate is used as a poor solvent to precipitate the precipitate. The above precipitation-dissolution process is repeated three times to ensure that the ligands are fully exchanged so as to completely coat the surface of the perovskite nanorods.

[0025] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) Poly(4-vinylpyridine) (P4VP) and poly(trifluoroethyl methacrylate) (PTFEMA) form a star-shaped 21-arm block copolymer under the initiation of cyclodextrin. After end-group sulfonation treatment, it can be stably bound to the surface of perovskite nanorods, which significantly improves the stability of perovskite nanorods in extreme environments such as ambient temperature and high temperature and pure polar solvent environment, so that its fluorescence intensity can be maintained at a high level; (2) The operation process is simple, the reaction conditions are mild, no complex equipment is required, it is suitable for perovskite nanorods of different types and sizes, the raw materials used are inexpensive, and the process is easy to scale up, providing a practical and feasible technical path for the large-scale and low-cost preparation of high-performance perovskite nanocomposites. Attached Figure Description

[0026] Figure 1 This is a transmission electron microscope (TEM) image of CsPbBr3 perovskite nanorods grafted with sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymer prepared in Example 1 of the present invention.

[0027] Figure 2 The graph shows the atmospheric fluorescence intensity retention rate of the perovskite nanorods prepared in Examples 1-2 and Comparative Examples 1-8 of this invention.

[0028] Figure 3 The graph shows the fluorescence intensity retention rate of the perovskite nanorods prepared in Examples 1-2, Comparative Examples 3 and 5 of this invention at a high temperature of 90℃.

[0029] Figure 4 The graph shows the retention rate of fluorescence intensity in the isopropanol polar environment of the perovskite nanorods prepared in Examples 1-2, Comparative Examples 3 and 5 of this invention. Detailed Implementation

[0030] The technical solution of the present invention will be further described below with reference to the embodiments, comparative examples and accompanying drawings. Unless otherwise stated, all reagents used are commercially available and are used directly without purification.

[0031] Example 1

[0032] The surface-modified metal halide perovskite nanorod composite luminescent material of this embodiment comprises the following components by mass percentage: 25 wt% P4VP, 50 wt% PTFEMA and 25 wt% metal halide perovskite nanorods.

[0033] The surface-modified metal halide perovskite nanorod composite luminescent material was prepared by the following method:

[0034] (1) Preparation of star-shaped 21-arm P4VP-PTFEMA block copolymer:

[0035] One mole of β-cyclodextrin, 15 mL of N-methylpyrrolidone, 30 moles of 2-bromoisobutyryl bromide, and a magnetic stir bar were placed in a three-necked flask and stirred at room temperature under a nitrogen atmosphere for 24 hours. After the reaction was complete, the solution was added to 50 mL of ice-cold methanol, filtered, and dried at room temperature to obtain brominated β-cyclodextrin. In another three-necked flask, one mole of 2-(dodecyltrithiocarbonate)-2-methylpropionic acid (DDMAT), 15 mL of anhydrous tetrahydrofuran, and 2 moles of hydrazine hydrate were added, and the mixture was stirred at room temperature, protected from light, and under an inert atmosphere for 24 hours. After the reaction was complete, the solution was concentrated by rotary evaporation, and the product was separated by column chromatography (using n-hexane as the mobile phase and anhydrous silica gel as the solid phase). Finally, the product was concentrated by low-temperature rotary evaporation to obtain solid-state thiolized DDMAT. Subsequently, 1 molar amount of brominated β-cyclodextrin, 20 mL of anhydrous N,N-dimethylformamide (DMF), 30 molar amount of thiolated DDMAT, and 1 mL of triethylamine were added to a dry reaction flask. The mixture was stirred at room temperature and in the dark for 24 hours. After the reaction was completed, the solution was precipitated in 100 mL of ice-cold methanol, filtered, and dried at room temperature to obtain solid DDMAT-functionalized β-cyclodextrin.

[0036] One mole of DDMAT-functionalized β-cyclodextrin, 0.2 moles of azobisisobutyronitrile (AIBN), 300 moles of DMF, 300 moles of 4-VP, and a magnetic stir bar were placed in a reaction vessel and sealed with a rubber stopper. An inert gas was introduced for 30 minutes to purge air. After bubbling, the reaction vessel was placed in an oil bath at 60°C and reacted for 6 hours. After the reaction, the reaction mixture was diluted with tetrahydrofuran and precipitated using ice-cold methanol solution to obtain an intermediate product. Then, one mole of the above intermediate product, along with 0.2 moles of AIBN, 300 moles of DMF, 300 moles of TFEMA, and a magnetic stir bar, were placed in a reaction vessel, sealed with a rubber stopper, and the bubbling and reaction procedures were repeated. The mixture was reacted in an oil bath at 65°C for 6 hours. After the reaction was completed, the reaction mixture was diluted with tetrahydrofuran and precipitated with ice-cold methanol solution to obtain the product. The product was dried at room temperature in a vacuum drying oven for 48 h to obtain a star-shaped 21-arm P4VP-PTFEMA block copolymer, wherein the molecular weight of P4VP was 2500 kg / mol and the molecular weight of PTFEMA was 5000 kg / mol.

[0037] (2) End-group sulfonation treatment of star-shaped 21-arm P4VP-PTFEMA block copolymer:

[0038] Dissolve 1 mole of the above-mentioned star-shaped 21-arm P4VP-PTFEMA block copolymer in 30 mL of toluene solution. Place the solution in an ice bath and slowly add 10 moles of m-chloroperoxybenzoic acid dropwise. After the addition is complete, stir the mixture at 0 °C for 12 h. After stirring, precipitate the precipitate with ice-cold methanol solution. After standing overnight in a refrigerator, discard the supernatant, collect the bottom precipitate, and vacuum dry it at room temperature for 48 h to obtain the sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymer.

[0039] (3) Preparation of CsPbBr3 perovskite nanorods grafted with sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymer:

[0040] One part by mass of cesium carbonate (Cs₂CO₃), three parts by mass of oleic acid, and 15 parts by mass of octadecene were placed in a three-necked flask and degassed at 120°C for 90 minutes. The system temperature was then raised to 150°C and maintained under an inert atmosphere for 2 hours to obtain the cesium salt precursor. In another three-necked flask, one part by mass of lead bromide (PbBr₂), six parts by mass of octylamine, nine parts by mass of oleylamine, and 40 parts by mass of octadecene were mixed and degassed at 120°C for 1 hour. The system temperature was then raised to 125°C and maintained under an inert atmosphere for 30 minutes, and the aforementioned cesium salt precursor, preheated to 120°C, was rapidly injected. After reacting for 30 seconds, the three-necked flask was transferred to an ice bath for rapid cooling. After the mixture cooled to room temperature, an appropriate amount of n-hexane was added, and the mixture was centrifuged at 6000 rpm for 10 minutes. The precipitate was collected to obtain CsPbBr3 perovskite nanorods co-terminated with octylamine / oleylamine. The product was redispersed in toluene and stored in toluene medium for later use.

[0041] An appropriate amount of ethyl acetate was added to a toluene solution containing 1 part by mass of the aforementioned octylamine / oleylamine co-terminated CsPbBr3 perovskite nanorods, and the mixture was centrifuged at 6000 rpm for 5 min to obtain a nanorod precipitate. Three parts by mass of the aforementioned sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymer were dispersed in toluene to obtain a clear solution. The aforementioned octylamine / oleylamine co-terminated CsPbBr3 perovskite nanorod precipitate was then added, and the mixture was sonicated to ensure uniform dispersion. A ligand exchange reaction occurred, grafting the sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymer onto the surface of the perovskite nanorods. The above precipitation-dissolution process was repeated three times to ensure sufficient ligand exchange. Finally, ethyl acetate was used as a poor solvent to precipitate the CsPbBr3 perovskite nanorods grafted with the sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymer. After centrifugation at 6000 rpm for 5 min, the precipitate was dispersed in toluene and stored.

[0042] Example 2

[0043] The surface-modified metal halide perovskite nanorod composite luminescent material of this embodiment comprises the following components by mass percentage: 27.5 wt% P4VP, 55 wt% PTFEMA and 17.5 wt% metal halide perovskite nanorods.

[0044] The surface-modified metal halide perovskite nanorod composite luminescent material was prepared by the following method:

[0045] (1) Preparation of star-shaped 21-arm P4VP-PTFEMA block copolymer:

[0046] One mole of β-cyclodextrin, 15 mL of N-methylpyrrolidone, 50 moles of 2-bromoisobutyryl bromide, and a magnetic stir bar were placed in a three-necked flask and stirred at room temperature under a nitrogen atmosphere for 24 hours. After the reaction was complete, the solution was added to 50 mL of ice-cold methanol, filtered, and dried at room temperature to obtain brominated β-cyclodextrin. In another three-necked flask, one mole of 2-(dodecyltrithiocarbonate)-2-methylpropionic acid (DDMAT), 15 mL of anhydrous tetrahydrofuran, and 5 moles of hydrazine hydrate were added, and the mixture was stirred at room temperature, protected from light, and under an inert atmosphere for 24 hours. After the reaction was complete, the solution was concentrated by rotary evaporation, and the product was separated by column chromatography (using n-hexane as the mobile phase and anhydrous silica gel as the solid phase). Finally, the product was concentrated by low-temperature rotary evaporation to obtain solid-state thiolized DDMAT. Subsequently, 1 molar amount of brominated β-cyclodextrin, 20 mL of anhydrous N,N-dimethylformamide (DMF), 50 molar amount of thiolated DDMAT, and 2 mL of triethylamine were added to a dry reaction flask. The mixture was stirred at room temperature and in the dark for 24 hours. After the reaction was completed, the solution was precipitated in 100 mL of ice-cold methanol, filtered, and dried at room temperature to obtain solid DDMAT-functionalized β-cyclodextrin.

[0047] One mole of DDMAT-functionalized β-cyclodextrin, 0.2 moles of azobisisobutyronitrile (AIBN), 300 moles of DMF, 300 moles of 4-VP, and a magnetic stir bar were placed in a reaction vessel and sealed with a rubber stopper. An inert gas was introduced for 30 minutes to purge air. After bubbling, the reaction vessel was placed in an oil bath at 60°C and reacted for 8 hours. After the reaction, the reaction mixture was diluted with tetrahydrofuran and precipitated using ice-cold methanol solution to obtain an intermediate product. Then, one mole of the above intermediate product, along with 0.2 moles of AIBN, 300 moles of DMF, 300 moles of TFEMA, and a magnetic stir bar, were placed in a reaction vessel, sealed with a rubber stopper, and the bubbling and reaction procedures were repeated. The mixture was reacted in an oil bath at 65°C for 8 hours. After the reaction was completed, the reaction mixture was diluted with tetrahydrofuran and precipitated with ice-cold methanol solution to obtain the product. The product was dried at room temperature in a vacuum drying oven for 48 h to obtain a star-shaped 21-arm P4VP-PTFEMA block copolymer.

[0048] (2) End-group sulfonation treatment of star-shaped 21-arm P4VP-PTFEMA block copolymer:

[0049] Dissolve 1 mole of the star-shaped 21-arm P4VP-PTFEMA block copolymer in 30 mL of toluene solution. Place the solution in an ice bath and slowly add 20 moles of m-chloroperoxybenzoic acid. After the addition is complete, stir the mixture at 0 °C for 12 h. After stirring, precipitate the precipitate with ice-cold methanol solution. After standing overnight in a refrigerator, discard the supernatant, collect the bottom precipitate, and vacuum dry it at room temperature for 48 h to obtain the sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymer, wherein the molecular weight of P4VP is 7500 kg / mol and the molecular weight of PTFEMA is 15000 kg / mol.

[0050] (3) Preparation of CsPbBr3 perovskite nanorods grafted with sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymer:

[0051] One part by mass of cesium carbonate (Cs₂CO₃), three parts by mass of oleic acid, and 15 parts by mass of octadecene were placed in a three-necked flask and degassed at 120°C for 90 minutes. The system temperature was then raised to 150°C and maintained under an inert atmosphere for 2 hours to obtain the cesium salt precursor. In another three-necked flask, one part by mass of lead bromide (PbBr₂), six parts by mass of octylamine, nine parts by mass of oleylamine, and 40 parts by mass of octadecene were mixed and degassed at 120°C for 1 hour. The system temperature was then raised to 125°C and maintained under an inert atmosphere for 30 minutes, and the aforementioned cesium salt precursor, preheated to 120°C, was rapidly injected. After reacting for 30 seconds, the three-necked flask was transferred to an ice bath for rapid cooling. After the mixture cooled to room temperature, an appropriate amount of n-hexane was added, and the mixture was centrifuged at 6000 rpm for 10 minutes. The precipitate was collected to obtain CsPbBr3 perovskite nanorods co-terminated with octylamine / oleylamine. The product was redispersed in toluene and stored in toluene medium for later use.

[0052] An appropriate amount of ethyl acetate was added to a toluene solution containing 1 part by mass of the aforementioned octylamine / oleylamine co-terminated CsPbBr3 perovskite nanorods, and the mixture was centrifuged at 6000 rpm for 5 min to obtain a nanorod precipitate. Three parts by mass of the aforementioned sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymer were dispersed in toluene to obtain a clear solution. The aforementioned octylamine / oleylamine co-terminated CsPbBr3 perovskite nanorod precipitate was then added, and the mixture was sonicated to ensure uniform dispersion. A ligand exchange reaction occurred, grafting the sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymer onto the surface of the perovskite nanorods. The above precipitation-dissolution process was repeated three times to ensure sufficient ligand exchange. Finally, ethyl acetate was used as a poor solvent to precipitate the CsPbBr3 perovskite nanorods grafted with the sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymer. After centrifugation at 6000 rpm for 5 min, the precipitate was dispersed in toluene and stored.

[0053] Comparative Example 1: CsPbBr3 perovskite nanorods co-terminated with octylamine / oleylamine

[0054] One part by mass of cesium carbonate (Cs₂CO₃), three parts by mass of oleic acid, and 15 parts by mass of octadecene were placed in a three-necked flask and degassed at 120°C for 90 minutes. The system temperature was then raised to 150°C and maintained under an inert atmosphere for 2 hours to obtain the cesium salt precursor. In another three-necked flask, one part by mass of lead bromide (PbBr₂), six parts by mass of octylamine, nine parts by mass of oleylamine, and 40 parts by mass of octadecene were mixed and degassed at 120°C for 1 hour. The system temperature was then raised to 125°C and maintained under an inert atmosphere for 30 minutes, and the aforementioned cesium salt precursor, preheated to 120°C, was rapidly injected. After reacting for 30 seconds, the three-necked flask was transferred to an ice bath for rapid cooling. After the mixture cooled to room temperature, an appropriate amount of n-hexane was added, and the mixture was centrifuged at 6000 rpm for 10 minutes. The precipitate was collected to obtain CsPbBr3 perovskite nanorods co-terminated with octylamine / oleylamine. The product was redispersed in toluene and stored in toluene medium for later use.

[0055] Comparative Example 2: Linear poly(4-vinylpyridine)-grafted CsPbBr3 perovskite nanorods

[0056] A suitable amount of ethyl acetate was added to a toluene solution of octylamine / oleylamine co-terminated CsPbBr3 perovskite nanorods prepared in Comparative Example 1 (1 part by mass), and the solution was centrifuged at 6000 rpm for 5 min to obtain nanorod precipitate. Three parts by mass of 22500 kg / mol sulfonic acid-terminated linear poly(4-vinylpyridine) were dispersed in toluene to obtain a clear solution. The aforementioned CsPbBr3 perovskite nanorod precipitate was then added, and the solution was sonicated to ensure uniform dispersion. A ligand exchange reaction occurred, grafting the sulfonic acid-terminated linear poly(4-vinylpyridine) onto the surface of the perovskite nanorods. The precipitation-dissolution process was repeated three times to ensure sufficient ligand exchange. Finally, ethyl acetate was used as a poor solvent to precipitate the sulfonic acid-terminated linear poly(4-vinylpyridine)-grafted CsPbBr3 perovskite nanorods. After centrifugation at 6000 rpm for 5 min, the precipitate was dispersed in toluene and stored.

[0057] Comparative Example 3: Star-shaped poly(4-vinylpyridine)-grafted CsPbBr3 perovskite nanorods

[0058] A suitable amount of ethyl acetate was added to a toluene solution of octylamine / oleylamine co-terminated CsPbBr3 perovskite nanorods prepared in Comparative Example 1 (1 part by mass), and the solution was centrifuged at 6000 rpm for 5 min to obtain nanorod precipitate. Three parts by mass of 22500 kg / mol sulfonic acid-terminated star-shaped poly(4-vinylpyridine) were dispersed in toluene solution to obtain a clear solution. The aforementioned CsPbBr3 perovskite nanorod precipitate was then added, and the solution was sonicated to ensure uniform dispersion. A ligand exchange reaction occurred, grafting the sulfonic acid-terminated star-shaped poly(4-vinylpyridine) onto the surface of the perovskite nanorods. The precipitation-dissolution process was repeated three times to ensure complete ligand exchange. Finally, ethyl acetate was used as a poor solvent to precipitate the sulfonic acid-terminated star-shaped poly(4-vinylpyridine)-grafted CsPbBr3 perovskite nanorods. After centrifugation at 6000 rpm for 5 min, the precipitate was dispersed in toluene solution for storage.

[0059] Comparative Example 4: Linear poly(trifluoroethyl methacrylate) grafted CsPbBr3 perovskite nanorods

[0060] A suitable amount of ethyl acetate was added to a toluene solution of octylamine / oleylamine co-terminated CsPbBr3 perovskite nanorods prepared in Comparative Example 1 (1 part by mass), and the solution was centrifuged at 6000 rpm for 5 min to obtain nanorod precipitate. Three parts by mass of 22500 kg / mol sulfonic acid-terminated linear poly(trifluoroethylene methacrylate) were dispersed in toluene solution to obtain a clear solution. The aforementioned CsPbBr3 perovskite nanorod precipitate was then added, and the solution was sonicated to ensure uniform dispersion. A ligand exchange reaction occurred, grafting the sulfonic acid-terminated linear poly(trifluoroethylene methacrylate) onto the surface of the perovskite nanorods. The precipitation-dissolution process was repeated three times to ensure sufficient ligand exchange. Finally, ethyl acetate was used as a poor solvent to precipitate the sulfonic acid-terminated linear poly(trifluoroethylene methacrylate) grafted CsPbBr3 perovskite nanorods. After centrifugation at 6000 rpm for 5 min, the precipitate was dispersed in toluene solution for storage.

[0061] Comparative Example 5: Star-shaped CsPbBr3 perovskite nanorods grafted with trifluoroethyl methacrylate

[0062] A suitable amount of ethyl acetate was added to a toluene solution of CsPbBr3 perovskite nanorods co-terminated with octylamine / oleylamine prepared in Comparative Example 1, and the solution was centrifuged at 6000 rpm for 5 min to obtain nanorod precipitate. Three parts by mass of 22500 kg / mol sulfonic acid-terminated star-shaped poly(trifluoroethyl methacrylate) were dispersed in toluene to obtain a clear solution. The aforementioned CsPbBr3 perovskite nanorod precipitate was then added, and the solution was sonicated to ensure uniform dispersion. A ligand exchange reaction occurred, grafting the sulfonic acid-terminated star-shaped poly(trifluoroethyl methacrylate) onto the surface of the perovskite nanorods. The precipitation-dissolution process was repeated three times to ensure sufficient ligand exchange. Finally, ethyl acetate was used as a poor solvent to precipitate the sulfonic acid-terminated star-shaped poly(trifluoroethyl methacrylate) grafted CsPbBr3 perovskite nanorods. After centrifugation at 6000 rpm for 5 min, the nanorods were dispersed in toluene and stored.

[0063] Comparative Example 6: Star-shaped CsPbBr3 perovskite nanorods blended with poly(4-vinylpyridine)

[0064] A suitable amount of ethyl acetate was added to a toluene solution of CsPbBr3 perovskite nanorods co-terminated with octylamine / oleylamine prepared in Comparative Example 1 (1 part by mass), and the mixture was centrifuged at 6000 rpm for 5 min to obtain nanorod precipitate. Three parts by mass of 22500 kg / mol star-shaped poly(4-vinylpyridine) were mixed with the aforementioned CsPbBr3 perovskite nanorod precipitate and sonicated for 1 hour to ensure uniform dispersion, thus obtaining CsPbBr3 perovskite nanorods blended with star-shaped poly(4-vinylpyridine).

[0065] Comparative Example 7: CsPbBr3 perovskite nanorods blended with star-shaped poly(trifluoroethyl methacrylate)

[0066] A suitable amount of ethyl acetate was added to a toluene solution of CsPbBr3 perovskite nanorods co-capped with octylamine / oleylamine prepared in Comparative Example 1 (1 part by mass), and the mixture was centrifuged at 6000 rpm for 5 min to obtain nanorod precipitate. Three parts by mass of 22500 kg / mol star-shaped poly(trifluoroethyl methacrylate) were mixed with the aforementioned CsPbBr3 perovskite nanorod precipitate and sonicated for 1 hour to ensure uniform dispersion, thus obtaining CsPbBr3 perovskite nanorods blended with star-shaped poly(trifluoroethyl methacrylate).

[0067] Comparative Example 8: Star-shaped polystyrene-grafted CsPbBr3 perovskite nanorods

[0068] A suitable amount of ethyl acetate was added to a toluene solution of octylamine / oleylamine co-terminated CsPbBr3 perovskite nanorods prepared in Comparative Example 1 (1 part by mass), and the solution was centrifuged at 6000 rpm for 5 min to obtain nanorod precipitate. Three parts by mass of 22500 kg / mol sulfonic acid-terminated star-shaped polystyrene were dispersed in toluene solution to obtain a clear solution. The aforementioned CsPbBr3 perovskite nanorod precipitate was then added, and the solution was sonicated to ensure uniform dispersion. A ligand exchange reaction occurred, grafting the sulfonic acid-terminated star-shaped polystyrene onto the surface of the perovskite nanorods. This precipitation-dissolution process was repeated three times to ensure complete ligand exchange. Finally, ethyl acetate was used as a poor solvent to precipitate the sulfonic acid-terminated star-shaped polystyrene-grafted CsPbBr3 perovskite nanorods. After centrifugation at 6000 rpm for 5 min, the precipitate was dispersed in toluene solution for storage.

[0069] The morphology of CsPbBr3 nanorods grafted with sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymer prepared in Example 1 was analyzed by transmission electron microscopy (TEM). Figure 1 As shown, the nanorods have an average diameter of approximately 10 nm and a length of approximately 100 nm.

[0070] The nanorod materials prepared in Examples 1-2 and Comparative Examples 1-8 were placed in an atmospheric environment for fluorescence intensity retention tests. The results are shown in Table 1 and Table 2. Figure 2 As shown in Table 1 and Figure 2It can be seen that the surface-modified perovskite nanorods prepared in Examples 1-2 still maintained more than 95% of their original fluorescence intensity after 60 days of exposure, while the unmodified perovskite nanorods prepared in Comparative Example 1 showed no fluorescence after 10 days. The polymer-grafted perovskite nanorods prepared in Comparative Examples 2-5 and 8 showed significantly lower fluorescence retention rates at 60 days compared to Examples 1-2. This indicates that grafting with sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymer can effectively improve the stability of nanorods, and its stabilizing effect on perovskite nanorods is significantly better than that of PS. Furthermore, P4VP and PTFEMA have a synergistic effect; preparing them as star-shaped block copolymers and performing end-group sulfonation treatment can significantly improve the coating effect on perovskite nanorods. Comparative Examples 6-7 show that star-shaped P4VP and star-shaped PTFEMA cannot stably coat the surface of perovskite nanorods through physical mixing.

[0071] Table 1. Fluorescence intensity retention of perovskite nanorods prepared in Examples 1-2 and Comparative Examples 1-8 in atmospheric environment for 60 days.

[0072] Sample Fluorescence intensity retention rate (%) within 60 days Example 1 95.2 Example 2 98.0 Comparative Example 1 0 Comparative Example 2 86.7 Comparative Example 3 89.8 Comparative Example 4 77.6 Comparative Example 5 88.1 Comparative Example 6 67.1 Comparative Example 7 61.3 Comparative Example 8 21.0

[0073] Using Examples 1-2 and Comparative Examples 3 and 5, which showed fluorescence intensity retention rates higher than 88% over 60 days in atmospheric conditions, the corresponding nanorod materials were placed in a 90°C high-temperature environment for fluorescence intensity retention rate testing. The results are shown in Table 2 and... Figure 3 As shown in Table 2 and Figure 3 It can be seen that the perovskite nanorods prepared in Examples 1-2 still maintained more than 80% of their original fluorescence intensity after being exposed at 90°C for 72 hours, while the perovskite nanorods with sulfonic acid-terminated star-shaped P4VP grafts prepared in Comparative Example 3 had no fluorescence after 24 hours, and the perovskite nanorods with sulfonic acid-terminated star-shaped PTFEMA grafts prepared in Comparative Example 5 had no fluorescence after 30 hours. This indicates that the grafting of sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymers can effectively improve the stability of perovskite nanorods at high temperatures.

[0074] Table 2. Fluorescence intensity retention of perovskite nanorods prepared in Examples 1-2, Comparative Examples 3 and 5 at 90°C.

[0075] Sample Fluorescence intensity retention rate (%) within 72 hours Example 1 80.6 Example 2 82.4 Comparative Example 3 0 Comparative Example 5 0

[0076] The nanorod materials prepared in Examples 1-2, Comparative Examples 3 and 5 were then placed in a pure isopropanol polar environment for fluorescence intensity retention testing. The results are shown in Table 3 and... Figure 4 As shown in Table 3 and Figure 4It can be seen that the perovskite nanorods prepared in Examples 1-2 still maintained more than 60% of their original fluorescence intensity after 72 hours of exposure in polar solution, while the sulfonic acid-terminated star-shaped P4VP-grafted perovskite nanorods prepared in Comparative Example 3 had no fluorescence after 24 hours, and the sulfonic acid-terminated star-shaped PTFEMA-grafted perovskite nanorods prepared in Comparative Example 5 had no fluorescence after 12 hours. It can be seen that the sulfonic acid-terminated star-shaped 21-arm P4VP-PTFEMA block copolymer grafting can effectively improve the stability of perovskite nanorods in a pure polar solvent environment.

[0077] Table 3. Fluorescence intensity retention of perovskite nanorods prepared in Examples 1-2, Comparative Examples 3 and 5 in isopropanol polar environment.

[0078] Sample Fluorescence intensity retention rate (%) within 72 hours Example 1 61.8 Example 2 64.6 Comparative Example 3 0 Comparative Example 5 0

[0079] In summary, the surface-modified perovskite nanorod composite luminescent material prepared by this invention not only exhibits excellent and long-lasting fluorescence intensity retention under ambient temperature conditions, but also remains stable under extreme conditions such as high temperature and pure polar solvent environments, showing great promise for applications in optoelectronic devices and other fields.

Claims

1. A surface-modified metal halide perovskite nanorod composite luminescent material, characterized in that, It includes metal halide perovskite nanorods and surface copolymers, wherein the metal halide perovskite nanorods are bromo-lead-cesium perovskite nanorods, and the surface copolymers are sulfonic acid-terminated star-shaped 21-arm poly(4-vinylpyridine-poly(trifluoroethyl methacrylate)) block copolymers.

2. The surface-modified metal halide perovskite nanorod composite luminescent material according to claim 1, characterized in that, The metal halide perovskite nanorods have a mass percentage of 17.5-25 wt%, poly(4-vinylpyridine) has a mass percentage of 25-27.5 wt%, and poly(trifluoroethyl methacrylate) has a mass percentage of 50-55 wt%.

3. A method for preparing a surface-modified metal halide perovskite nanorod composite luminescent material as described in claim 1 or 2, characterized in that, Includes the following steps: (1) Preparation of a star-shaped 21-arm block copolymer of poly(4-vinylpyridine)-poly(trifluoroethyl methacrylate); (2) Add a sulfonating agent to the aforementioned star-shaped 21-arm poly(4-vinylpyridine-poly(trifluoroethyl methacrylate)) block copolymer and perform end-group sulfonation treatment to obtain a sulfonic acid-terminated poly(4-vinylpyridine-poly(trifluoroethyl methacrylate)) block copolymer. (3) Prepare metal halide perovskite nanorods co-capped with octylamine / oleylamine, and graft the aforementioned sulfonic acid-capped star-shaped 21-arm poly(4-vinylpyridine-poly(trifluoroethyl methacrylate)) block copolymer onto the surface of the metal halide perovskite nanorods co-capped with octylamine / oleylamine.

4. The method for preparing the surface-modified metal halide perovskite nanorod composite luminescent material according to claim 3, characterized in that, In step (1), the preparation of the star-shaped 21-arm poly(4-vinylpyridine)-poly(trifluoroethyl methacrylate) block copolymer includes the following steps: after functionalizing cyclodextrin, it first undergoes a polymerization reaction with 4-vinylpyridine under the action of an initiator, and the resulting polymerization product then undergoes a polymerization reaction with trifluoroethyl methacrylate under the action of an initiator.

5. The method for preparing the surface-modified metal halide perovskite nanorod composite luminescent material according to claim 4, characterized in that, The functionalization process includes thiolation of cyclodextrin with 2-(dodecyltrithiocarbonate)-2-methylpropionic acid.

6. The method for preparing the surface-modified metal halide perovskite nanorod composite luminescent material according to claim 3, characterized in that, In step (2), the sulfonating agent is m-chloroperoxybenzoic acid.

7. The method for preparing the surface-modified metal halide perovskite nanorod composite luminescent material according to claim 3, characterized in that, In step (3), the metal halide perovskite nanorods co-capped with octylamine / oleylamine are prepared by hot injection method.

8. The method for preparing the surface-modified metal halide perovskite nanorod composite luminescent material according to claim 3, characterized in that, In step (3), the grafting involves dissolving the sulfonic acid-terminated star-shaped 21-arm poly(4-vinylpyridine-poly(trifluoroethyl methacrylate)) block copolymer in a solvent, adding the aforementioned octylamine / oleylamine co-terminated metal halide perovskite nanorods, and mixing them to allow a ligand exchange reaction to occur.

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