A Hemin-modified CsPbI3 perovskite quantum dot and its preparation method

Abstract

The application relates to a Hemin-modified CsPbI3 perovskite quantum dot and a preparation method thereof, and comprises a CsPbI3 perovskite quantum dot and a Hemin functional molecule combined on the surface of the CsPbI3 perovskite quantum dot. 2+ The two propionic acid side chains in the Hemin molecule can provide carboxyl coordination sites, and the uncoordinated Pb on the surface of the CsPbI3 quantum dot can be coordinated to the carboxyl coordination sites, so that stable coordination is formed, surface defects are passivated, and non-radiation recombination loss is reduced The Fe-porphyrin conjugated macrocyclic structure in the Hemin molecule has a certain steric hindrance effect, can form a protective functional interface on the surface of the quantum dot, and can inhibit the contact between the quantum dots, the agglomeration of the quantum dots and the structural degradation induced by the surface defects. Through the synergistic effect of the above chemical passivation and physical steric protection, the luminescent efficiency, the structural stability and the luminescent stability under the light and photo-thermal coupling conditions of the perovskite quantum dot can be improved.

Description

Technical Field

[0001] This invention belongs to the field of perovskite quantum dot material technology, specifically relating to a Hemin-modified CsPbI3 perovskite quantum dot and its preparation method. Background Technology

[0002] Red light is a key component in the red, green, and blue (RGB) three-primary-color display system, and its luminescent performance directly determines the color gamut coverage and color reproduction capability of display devices. With the rapid development of ultra-high-definition displays, Micro-LEDs, virtual reality (VR), laser displays, and optical communications, the demand for red-emitting materials with high color purity, high luminous efficiency, and high stability is increasing. Therefore, developing red-emitting materials that combine excellent luminescent performance and long-term stability has become an important research direction in the field of optoelectronics.

[0003] In recent years, halide perovskite quantum dots have attracted widespread attention due to their advantages such as high absorption coefficient, narrow emission half-width, high fluorescence quantum yield, and solution processability. Among them, all-inorganic CsPbI3 perovskite quantum dots, with emission wavelengths in the 620-700 nm range, can achieve high-purity red light emission and also possess excellent color coordinates and carrier transport properties, making them an important candidate material for next-generation red light display devices, lasers, and photodetectors.

[0004] However, compared to systems like CsPbCl3 and CsPbBr3, the stability problem of CsPbI3 quantum dots is particularly prominent. Due to the large radius of the I⁻ ion, the lattice structure of CsPbI3 is relatively weak, and it is prone to phase transition at room temperature, transforming into a non-luminescent phase. Essentially, the formation of iodine vacancies induces lattice distortion, and even aggregation between quantum dots; simultaneously, due to the large surface area of ​​quantum dots, uncoordinated Pb... 2+ The problems of halogen vacancies and dangling bond defects are more prominent. These defects can form deep level traps, accelerate the nonradiative recombination process of photogenerated carriers, and thus lead to a decrease in fluorescence quantum yield, a shortened luminescence lifetime, and a degradation of device performance.

[0005] Ligand engineering has become one of the most commonly used stabilization methods because it can directly control the chemical environment of quantum dot surfaces without significantly affecting their intrinsic optical properties. Currently, researchers have developed novel ligand systems such as multidentate carboxylic acid ligands, zwitterionic ligands, and functionalized organic molecules to achieve defect passivation by enhancing the binding affinity of ligands to quantum dot surfaces. However, most of these ligands require organic synthesis, which consumes large amounts of raw materials and may result in low yields.

[0006] Hemin is a natural heme that can be directly extracted from hemoglobin, making it an environmentally friendly process. Its molecular structure contains two propionic acid side chains, a porphyrin conjugated backbone, and a central iron ion. The two propionic acid side chains can provide carboxyl coordination sites, potentially enabling interaction with uncoordinated Pb groups on the surface of CsPbI3 quantum dots. 2+ Coordination occurs, thereby achieving relatively stable passivation of surface defects; at the same time, the Fe-porphyrin conjugated macrocyclic structure in Hemin can provide a certain steric hindrance effect, which can prevent the aggregation of quantum dots.

[0007] Based on these characteristics, Hemin molecules are expected to exert a dual effect of surface chemical passivation and physical steric hindrance, thereby reducing the defect density in CsPbI3 quantum dots, further reducing nonradiative recombination losses, and improving their luminescence stability under optical and photothermal coupling conditions. However, there are currently no related studies or reports on this technology.

[0008] Therefore, it is necessary to develop a Hemin-modified CsPbI3 perovskite quantum dot and its preparation method to solve the problems existing in the current technology. Summary of the Invention

[0009] To address the problems of poor lattice stability, high surface defect density, easy ligand desorption, easy quantum dot aggregation, and luminescence performance degradation under light or photothermal conditions in existing CsPbI3 red-light perovskite quantum dots, this invention provides a Hemin-modified CsPbI3 perovskite quantum dot and its preparation method. This invention utilizes the natural heme derivative Hemin to modify the surface of CsPbI3 red-light perovskite quantum dots. On one hand, the two propionic acid side chains in the Hemin molecule can provide carboxyl coordination sites, which can interact with uncoordinated Pb groups on the surface of the CsPbI3 quantum dots. 2+ Stable coordination is formed, thereby passivating surface defects and reducing nonradiative recombination losses. On the other hand, the Fe-porphyrin conjugated macrocyclic structure in the Hemin molecule has a certain steric hindrance effect, which can form a protective functional interface on the quantum dot surface, inhibiting contact, aggregation, and structural degradation induced by surface defects between quantum dots. Through the synergistic effect of the above chemical passivation and physical steric protection, this invention can improve the luminescence efficiency, structural stability, and luminescence stability under optical and photothermal coupling conditions of CsPbI3 red-light perovskite quantum dots. This invention achieves synergistic regulation of quantum dot surface defect passivation and physical barrier between quantum dots, which is of great significance for improving the luminescence efficiency and operational stability of red-light perovskite quantum dots.

[0010] One object of the present invention is to provide a Hemin-modified CsPbI3 perovskite quantum dot. The Hemin-modified CsPbI3 perovskite quantum dots comprise CsPbI3 perovskite quantum dots and Hemin functional molecules bound to the surface of the CsPbI3 perovskite quantum dots.

[0011] Furthermore, the Hemin molecule contains at least two carboxyl functional groups.

[0012] Furthermore, the Hemin molecule interacts with the Pb group on the surface of the CsPbI3 perovskite quantum dot via at least one carboxyl group. 2+ Formation of coordination structures.

[0013] Preferably, the Hemin molecule interacts with the Pb group on the surface of the CsPbI3 quantum dot via a dicarboxyl group. 2+ A double-toothed chelate structure is formed.

[0014] Preferably, the Hemin functional molecule comprises a Fe-porphyrin conjugated macrocyclic structure, which can provide steric hindrance on the surface of CsPbI3 quantum dots.

[0015] Furthermore, the emission peak of the CsPbI3 quantum dots is located in the range of 670-690 nm.

[0016] Furthermore, the surface ligands of the CsPbI3 quantum dots include oleic acid (OA), oleylamine (OAm), and Hemin.

[0017] Furthermore, the average fluorescence lifetime of the CsPbI3 perovskite quantum dots is 40-50 ns.

[0018] Preferably, the average fluorescence lifetime of the CsPbI3 perovskite quantum dots is approximately 43.1 ns.

[0019] Furthermore, the average fluorescence lifetime of the Hemin-modified CsPbI3 perovskite quantum dots is ≥55 ns.

[0020] Preferably, the average fluorescence lifetime of the Hemin-modified CsPbI3 perovskite quantum dots is ≥99 ns.

[0021] Another object of the present invention is to provide a method for preparing the above-mentioned Hemin-modified CsPbI3 perovskite quantum dots, comprising the following steps: S1. Add Cs2CO3 and PbBr2 to octadecene, then add oleic acid and oleylamine, and sonicate to obtain CsPbBr3 quantum dot solution; S2. Purify the CsPbBr3 quantum dot solution, disperse the obtained CsPbBr3 quantum dots in a solvent, and obtain a CsPbBr3 quantum dot dispersion. S3. Add PbI2 to a mixture of oleic acid and oleylamine, stir to obtain an iodine source solution, and then add the CsPbBr3 quantum dot dispersion to the iodine source solution to carry out anion exchange reaction to obtain a CPI quantum dot solution. S4. Purify the CPI quantum dot solution to remove excess PbI2 powder and obtain a CPI quantum dot dispersion; S5. Add Hemin to the solvent and disperse to obtain a Hemin solution; S6. Add the Hemin solution to the CPI quantum dot dispersion to carry out a ligand exchange reaction and obtain a reaction solution; S7. Purify the reaction solution and disperse the product in a solvent to obtain a Hemin-modified CsPbI3 perovskite quantum dot solution.

[0022] Furthermore, in step S3, the temperature of the anion exchange reaction is 40-50℃, and the time is 0.1-1 h.

[0023] Furthermore, in step S6, the ligand exchange reaction is carried out at a temperature of 40-50°C for a time of 0.1-1 h.

[0024] Furthermore, the mass ratio of Cs2CO3, PbI2 and Hemin is 0.0326:0.1383:0.0050.

[0025] Furthermore, in step S6, the concentration of Hemin is 2.5 mg / mL.

[0026] Another object of the present invention is to provide the application of the above-mentioned Hemin-modified CsPbI3 perovskite quantum dots in light-emitting devices.

[0027] Furthermore, the light-emitting device includes one or more of the following: light-emitting diode, micro-LED, laser, display device, and photodetector.

[0028] The present invention has the following beneficial effects: (1) This invention utilizes the dicarboxyl group structure in the Hemin molecule and the uncoordinated Pb on the quantum dot surface. 2+ The formation of stable coordination can effectively passivate surface defects of quantum dots and reduce defect-induced nonradiative recombination losses, thereby improving the luminescence efficiency and carrier lifetime of red perovskite quantum dots.

[0029] (2) The present invention utilizes the Fe-porphyrin conjugated macrocyclic structure in the Hemin molecule to form a certain steric hindrance protection on the surface of quantum dots, which can suppress the aggregation between quantum dots and the structural degradation induced by surface defects, thereby improving the structural stability of red light perovskite quantum dots.

[0030] (3) The CPI-Hemin constructed in this invention has both chemical passivation and physical steric hindrance protection, which can synergistically improve the luminescence stability of red perovskite quantum dots under light and photothermal coupling conditions.

[0031] (4) The Hemin used in this invention is a natural heme derivative with a relatively wide range of sources. It does not require complex organic synthesis steps and has the advantages of being green, simple and low-cost.

[0032] (5) The present invention can realize the preparation of CPI-Hemin composite quantum dots by using a one-step ultrasonic method combined with a ligand exchange strategy. The process is simple, has good repeatability, does not require complex equipment and special reaction conditions, and has the potential for further scale-up preparation and industrial application. Attached Figure Description

[0033] Figure 1 A schematic diagram of the preparation process of the CPI-Hemin quantum dots of the present invention is shown.

[0034] Figure 2 A schematic diagram of the Hemin molecular structure is shown.

[0035] Figure 3 The performance spectra of CPI-Hemin quantum dots with different Hemin addition amounts are shown. in, Figure 3 a represents the PLQY map. Figure 3 b is the fluorescence lifetime spectrum.

[0036] Figure 4 The absorption and emission spectra of CPI quantum dots and CPI-Hemin quantum dots are shown.

[0037] Figure 5 The characterization results of the coordination interaction between Hemin and CPI quantum dots are shown; in, Figure 5 a represents the Raman spectrum. Figure 5 b represents the Fourier transform infrared spectrum. Figure 5 c represents the X-ray photoelectron spectrum.

[0038] Figure 6 TEM images of CPI quantum dots and CPI-Hemin quantum dots are shown; in, Figure 6 a is a TEM image of CPI quantum dots. Figure 6 b is a TEM image of CPI-Hemin quantum dots. Figure 6 c represents the particle size distribution of CPI quantum dots. Figure 6 d represents the particle size distribution of CPI-Hemin quantum dots.

[0039] Figure 7 The results of stability tests on CPI and CPI-Hemin quantum dots under optical and photothermal coupling conditions are shown. in, Figure 7 a shows the emission spectra of CPI quantum dots and CPI-Hemin quantum dots under continuous excitation at 343 nm. The detection wavelength for CPI quantum dots is 685 nm, and the detection wavelength for CPI-Hemin quantum dots is 683 nm. Figure 7 b shows the emission spectra of CPI quantum dots and CPI-Hemin quantum dots under continuous excitation with 343 nm excitation light, and under continuous heating with hot stages at 50℃, 65℃, and 80℃, respectively.

[0040] Figure 8 The fluorescence lifetime changes and PLQY spectra of CPI and CPI-Hemin quantum dots after optical and photothermal treatment are shown. in, Figure 8 a represents the fluorescence lifetime change spectrum. Figure 8 b represents the PLQY map. Detailed Implementation

[0041] To more clearly illustrate the technical solution of the present invention, the present invention will be further described below in conjunction with specific embodiments. Unless otherwise stated, the raw materials, reactions, and post-processing methods appearing in the embodiments are all commercially available raw materials and technical methods well known to those skilled in the art.

[0042] The terms "preferred," "more preferred," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0043] It should be understood that, except in any operational instance or otherwise indicated, the amounts or all figures representing ingredients used, for example, in the specification and claims, should be understood to be modified by the term "about" in all cases. Therefore, unless otherwise stated, the numerical parameters set forth in the following specification and appended claims are approximate values ​​varying according to the desired performance to be obtained according to the invention.

[0044] The following materials are used in this invention: 1-Octadecene: Grade 0815214, purchased from Maclean's.

[0045] Lead bromide: Grade 301008, purchased from Xi'an Baolait / Yu Riguang Energy.

[0046] Cesium carbonate: brand name, purchased from Maclean's.

[0047] Lead iodide: Grade 301007, purchased from Xi'an Baolait / Yu Riguang Energy.

[0048] n-Hexane: Grade H109654, purchased from Aladdin.

[0049] Methyl acetate: grade M103357, purchased from Aladdin.

[0050] Oleic acid: grade O108484, purchased from Aladdin.

[0051] Oleamine: Brand name O106967, purchased from Aladdin.

[0052] Hemin: Grade 27481A, purchased from Adamas.

[0053] Example 1 A type of CsPbI3 perovskite quantum dot based on Hemin modification. The Hemin-modified CsPbI3 perovskite quantum dots comprise CsPbI3 perovskite quantum dots and Hemin functional molecules bound to the surface of the CsPbI3 perovskite quantum dots. The Hemin molecule reacts with Pb on the surface of CsPbI3 quantum dots via dicarboxyl groups. 2+ Forming a double-toothed chelate structure; The method for preparing Hemin-modified CsPbI3 perovskite quantum dots includes the following steps: Preparation of S1 and CsPbBr3 quantum dots: Weigh 0.0326 g of Cs2CO3 and 0.1101 g of PbBr2, disperse them in 10 mL of octadecene, add 0.5 mL of OA and 0.5 mL of OAM, and react under ultrasonic conditions of 247 W for 10 min to obtain CsPbBr3 quantum dot solution; Purification of S2 and CsPbBr3 quantum dots: The CsPbBr3 quantum dot solution was centrifuged at 2000 rpm for 5 min to remove large precipitate particles, yielding a supernatant. Then, methyl acetate (supernatant to antisolvent volume ratio = 2:1) was added to the supernatant, and the mixture was centrifuged at 12000 rpm for 10 min to collect the precipitate. Subsequently, the precipitate was added to a mixture of methyl acetate and n-hexane (methyl acetate to n-hexane volume ratio = 1:1), and centrifuged at 12000 rpm for 10 min to collect the precipitate, which was the CsPbBr3 quantum dots. Finally, the obtained CsPbBr3 quantum dots were dispersed in 6 ml of n-hexane to obtain a CsPbBr3 quantum dot dispersion. Preparation of S3 and CPI quantum dots: Weigh 0.1383 g of PbI2, add 80 μL of OA and 80 μL of OAm, and stir at 40℃ for 30 min to obtain a homogeneous iodine source solution; CsPbBr3 quantum dot dispersion was added to the iodine source solution and stirred at 40°C for 30 min to complete the anion exchange reaction, thereby obtaining a CsPbI3 quantum dot solution with an emission peak at 683 nm, referred to as CPI quantum dot solution. Purification of S4 and CPI quantum dots: The CPI quantum dot solution was centrifuged at 1000 rpm for 6 min to remove excess PbI2 powder, resulting in a CPI quantum dot dispersion. Preparation of S5 and Hemin solutions: Weigh 5 mg of Hemin, add 2 mL of methyl acetate, and stir to disperse at 45°C to form a homogeneous Hemin solution; S6, Hemin surface modification: Add 2 mL of the Hemin solution to 3 mL of CPI quantum dot dispersion, stir at 45 °C for 15 min to perform ligand exchange, and obtain the reaction solution; S7. Purification Process The reaction solution was centrifuged at 12,000 rpm for 10 min. After discarding the supernatant, the precipitate was redispersed in 3 mL of n-hexane to obtain a CsPbI3 perovskite quantum dot solution modified with Hemin, referred to as CPI-Hemin quantum dot solution.

[0054] Figure 1 A schematic diagram of the preparation process of CPI-Hemin quantum dots in the embodiment is shown.

[0055] Figure 2 A schematic diagram of the Hemin molecular structure is shown.

[0056] Examples 2-5 The difference between Examples 2-5 and Example 1 is that in step S5, the mass of Hemin is modified to 1 mg, 3 mg, 7 mg and 10 mg respectively, while the other preparation methods are the same as in Example 1.

[0057] Comparative Example The difference between this comparative example and Example 1 is that Hemin molecules were not added, and unmodified CPI quantum dots (i.e., the CPI quantum dot dispersion obtained in step S4) were finally obtained.

[0058] Test case Test items: Fluorescence emission spectroscopy (PL); Time-resolved fluorescence spectroscopy (TRPL); Fluorescence quantum yield (PLQY); Fourier transform infrared spectroscopy (FTIR); Raman spectroscopy; X-ray photoelectron spectroscopy (XPS); Optical (343 nm, high-energy excitation light) stability test; Photothermal (343 nm light excitation with simultaneous application of 50℃, 65℃, and 80℃) stability test.

[0059] Figure 3 The results of PLQY and fluorescence lifetime of CPI-Hemin quantum dots with different Hemin addition amounts are shown.

[0060] Depend on Figure 3 As can be seen from b, with the increase of Hemin addition, the luminescence performance of quantum dots shows a trend of first increasing and then decreasing.

[0061] Among them, the unmodified CPI quantum dots had an average fluorescence lifetime of only 43.1 ns, while the sample modified with 5 mg Hemin had the best performance, with an average fluorescence lifetime of 99.1 ns.

[0062] When the amount of Hemin added was further increased to 10 mg, although the lifetime remained at a high level, the fluorescence intensity began to decrease. This indicates that an appropriate amount of Hemin can effectively reduce the surface defect density of quantum dots, while excessive Hemin may affect the luminescence performance due to intermolecular π-π stacking interactions.

[0063] Depend on Figure 3 PLQY in a also showed a similar trend, with the highest value (92.2%) in the 5 mg Hemin-modified sample.

[0064] Therefore, 5 mg Hemin was determined to be the preferred addition amount.

[0065] Figure 4 The absorption and emission spectra of Hemin, CPI quantum dots, and CPI-Hemin quantum dots are shown.

[0066] Depend on Figure 4It can be seen that the absorption of Hemin around 400 nm is the Soret band absorption, while the absorption of 525-625 nm is classified as the Q band absorption. After Hemin is combined, a new absorption peak of 410 nm appears in the CPI-Hemin quantum dot, indicating that Hemin has been successfully attached to the quantum dot.

[0067] Next, we can see that the emission peak of CPI quantum dots is 685 nm, while that of CPI-Hemin quantum dots is 683 nm. This is mainly attributed to the physical barrier of the porphyrin macrocyclic structure, which makes CPI-Hemin quantum dots smaller and causes a slight blue shift.

[0068] Figure 5 The Raman spectra, Fourier transform infrared spectra, and X-ray photoelectron spectroscopy results of CPI and CPI-Hemin quantum dots are shown.

[0069] Depend on Figure 5 It can be seen that the characteristic Fe-N vibrational peak and CN vibrational peak of Hemin appear in the CPI-Hemin sample.

[0070] Simultaneously, the characteristic C=O vibrational peak of Hemin, located at 1702 nm, was observed in the infrared spectrum. -1 .

[0071] Furthermore, the Pb 4f binding energy shows a significant shift compared to the unmodified CPI sample.

[0072] The above results indicate that Hemin molecules interact with uncoordinated Pb on the quantum dot surface via carboxyl groups. 2+ Coordination bonds are formed, achieving passivation of surface defects.

[0073] Figure 6 TEM images of CPI quantum dots and CPI-Hemin quantum dots are shown; in, Figure 6 a is a TEM image of CPI quantum dots. Figure 6 b is a TEM image of CPI-Hemin quantum dots. Figure 6 c represents the particle size distribution of CPI quantum dots. Figure 6 d represents the particle size distribution of CPI-Hemin quantum dots.

[0074] Depend on Figure 6 It can be seen that the size of CPI-Hemin quantum dots, 13.55 nm, is significantly smaller than that of CPI quantum dots, 16.04 nm. Furthermore, the quantum dots in the experimental group are spaced further apart. This can be attributed to the structure of the Hemin porphyrin macrocycle, which provides a physical barrier effect.

[0075] Figure 7The results of stability tests on CPI and CPI-Hemin quantum dots under optical and photothermal coupling conditions are shown. in, Figure 7 a shows the emission spectra of CPI quantum dots and CPI-Hemin quantum dots under continuous excitation at 343 nm. The detection wavelength for CPI quantum dots is 685 nm, and the detection wavelength for CPI-Hemin quantum dots is 683 nm. Figure 7 b shows the emission spectra of CPI quantum dots and CPI-Hemin quantum dots under continuous excitation with 343 nm excitation light, and under continuous heating with hot stages at 50℃, 65℃, and 80℃, respectively.

[0076] Depend on Figure 7 As can be seen, under the excitation condition of 343 nm, defined as @343, the results show that the luminescence intensity of CPI-Hemin quantum dots exhibits a high fluorescence retention rate, while the unmodified CPI quantum dots show a significant decay.

[0077] Depend on Figure 7 b shows that when excited at 343 nm and heated at 50, 65, and 80 °C respectively, the results are defined as @1, @2, and @3. The experimental group can still maintain a high luminescence effect, while the control group shows rapid luminescence decay under the action of this high temperature and high energy light.

[0078] Figure 8 The time-resolved fluorescence lifetime and PLQY results of CPI quantum dots and CPI-Hemin quantum dots after photothermal treatment are shown.

[0079] Depend on Figure 8 As can be seen from a, at @343, the average fluorescence lifetime increased to 1.13 μs.

[0080] @1, its average fluorescence lifetime increased to 1.27 μs; @2, its average fluorescence lifetime increased to 838.1 ns; @3, its average fluorescence lifetime increased to 376.1 ns.

[0081] Furthermore, Figure 8 b, @343, its PLQY increased to 94.6%.

[0082] @1, its PLQY increased to 96.8%; @2, its PLQY increased to 94.3%; @3, its PLQY increased to 93.6%.

[0083] Furthermore, the nonradiative recombination rate can be calculated using the following formula: Where, k r It is the radiative recombination rate, k nr It is the nonradiative recombination rate, τ int It is the average lifespan of the strength; Calculate the final nonradiative recombination rate k nr From the original unprocessed value of 0.787×10 6 s -1 The values ​​decreased to 0.0478×10. 6 s -1 (@343), 0.0252×10 6 s -1 (@1), 0.0680×10 6 s -1 (@2), 0.170×10 6 s -1 (@3).

[0084] The above results indicate that after Hemin modification is applied to the quantum dot surface, the bidentate chemical passivation and the physical barrier of the porphyrin macrocyclic structure can effectively reduce nonradiative recombination loss, thereby improving the long-term working stability of the quantum dots.

[0085] In summary, the CPI-Hemin quantum dots prepared by this invention can not only achieve surface defect passivation through dicarboxyl coordination, but also significantly improve the photostability and photothermal stability of quantum dots, showing good application prospects in the field of high-stability red light-emitting materials.

[0086] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0087] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A type of Hemin-modified CsPbI3 perovskite quantum dot, characterized in that, The Hemin-modified CsPbI3 perovskite quantum dots comprise CsPbI3 perovskite quantum dots and Hemin functional molecules bound to the surface of the CsPbI3 perovskite quantum dots.

2. The Hemin-modified CsPbI3 perovskite quantum dots according to claim 1, characterized in that, The Hemin molecule contains at least two carboxyl functional groups.

3. The Hemin-modified CsPbI3 perovskite quantum dots according to claim 2, characterized in that, The Hemin molecule binds to the Pb on the surface of the CsPbI3 quantum dot via at least one carboxyl group. 2+ Formation of coordination structures.

4. The Hemin-modified CsPbI3 perovskite quantum dots according to claim 1, characterized in that, The emission peak of the CsPbI3 quantum dots is located in the range of 670-690 nm.

5. The Hemin-modified CsPbI3 perovskite quantum dots according to claim 1, characterized in that, The average fluorescence lifetime of the Hemin-modified CsPbI3 perovskite quantum dots is ≥55 ns.

6. The method for preparing Hemin-modified CsPbI3 perovskite quantum dots according to any one of claims 1-5, characterized in that, Includes the following steps: S1. Add Cs2CO3 and PbBr2 to octadecene, then add oleic acid and oleylamine, and sonicate to obtain CsPbBr3 quantum dot solution; S2. Purify the CsPbBr3 quantum dot solution, disperse the obtained CsPbBr3 quantum dots in a solvent, and obtain a CsPbBr3 quantum dot dispersion. S3. Add PbI2 to a mixture of oleic acid and oleylamine, stir to obtain an iodine source solution, and then add the CsPbBr3 quantum dot dispersion to the iodine source solution to carry out anion exchange reaction to obtain a CPI quantum dot solution. S4. Purify the CPI quantum dot solution to remove excess PbI2 powder and obtain a CPI quantum dot dispersion; S5. Add Hemin to the solvent and disperse to obtain a Hemin solution; S6. Add the Hemin solution to the CPI quantum dot dispersion to carry out a ligand exchange reaction and obtain a reaction solution; S7. Purify the reaction solution and disperse the product in a solvent to obtain a Hemin-modified CsPbI3 perovskite quantum dot solution.

7. The method for preparing Hemin-modified CsPbI3 perovskite quantum dots according to claim 6, characterized in that, In step S3, the temperature of the anion exchange reaction is 40-50℃ and the time is 0.1-1 h.

8. The method for preparing Hemin-modified CsPbI3 perovskite quantum dots according to claim 6, characterized in that, In step S6, the ligand exchange reaction is carried out at a temperature of 40-50°C for a time of 0.1-1 h.

9. The application of Hemin-modified CsPbI3 perovskite quantum dots as described in any one of claims 1-5 in light-emitting devices.

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