A fluorescent molecule modified MXene material, a preparation method thereof and application thereof in a perovskite solar cell

Abstract

This invention provides a fluorescent molecule-modified MXene material, its preparation method, and its application in perovskite solar cells. The invention involves reacting fluorescent molecules with MXene materials to obtain fluorescent molecule-modified MXene materials, which can be used as interface modification layers in perovskite solar cells. Through the synergistic effect of fluorescent molecules and MXene, the invention achieves two main benefits: firstly, fluorescent molecules can effectively passivate interface defects and optimize energy level arrangement through their functional groups; secondly, the fluorescence properties of the fluorescent molecules can enhance the light absorption of the solar cell; and thirdly, MXene provides efficient charge transport channels. Through this synergistic effect, the photoelectric conversion efficiency and stability of the cell can be significantly improved. The preparation method provided by this invention is simple and low-cost, offering a new strategy for the fabrication of high-performance perovskite solar cells.

Description

Technical Field

[0001] This invention relates to the field of perovskite optoelectronic materials and devices, specifically to a fluorescent molecule-modified MXene material, its preparation method, and its application in perovskite solar cells. Background Technology

[0002] Perovskite solar cells, with their excellent photoelectric conversion performance and low-cost solution-processable characteristics, have become a research hotspot with great development potential in the photovoltaic field. They represent an important alternative to traditional silicon-based solar cells and show broad application prospects in photovoltaic power plants, flexible photovoltaic devices, and building-integrated photovoltaics (BIPV). In a formally structured perovskite solar cell, the interface performance between the electron transport layer and the perovskite light-absorbing layer is a key factor determining the overall photoelectric conversion efficiency, open-circuit voltage, fill factor, and other core indicators of the cell. This interface directly governs the electron extraction, transport, and injection processes. Its energy level matching degree, defect state density, and interface contact characteristics all play a decisive role in the charge transport efficiency and service stability of the cell. Therefore, optimizing the comprehensive performance of this interface has become a core research direction for the technological upgrading of perovskite solar cells.

[0003] Currently, tin dioxide (SnO2) is widely used as the electron transport material in perovskite solar cells with formal structures. To address various interface problems related to its compatibility with the perovskite light-absorbing layer, researchers have developed two main interface modification techniques: one is to introduce two-dimensional MXene materials for interface regulation, utilizing their high conductivity, tunable work function, and good compatibility with solution processing to optimize interface energy level matching and charge transport efficiency; the other is to use small organic molecules containing specific functional groups to passivate interface defects, leveraging the specific binding effects of sulfonic acid groups, carboxyl groups, hydroxyl groups, and other functional groups with perovskite interface defects to eliminate carrier recombination centers and improve the interface defect state density problem.

[0004] However, existing technologies still face numerous core bottlenecks that are difficult to overcome, preventing comprehensive optimization of the interface performance of perovskite solar cells. Specifically, firstly, the basic electron transport material SnO2 has inherent interface defects, resulting in energy level mismatch between it and commonly used perovskite materials. The energy "step" at the bottom of the conduction band severely hinders efficient electron extraction and injection, leading to significant open-circuit voltage loss. Simultaneously, a large amount of uncoordinated Pb at the perovskite interface... 2+Defects such as halogen vacancies easily become nonradiative recombination centers for charge carriers, and SnO2 is difficult to form ideal ohmic contacts with the upper and lower layers, easily increasing series resistance and significantly reducing the battery fill factor. Secondly, the modification effect of two-dimensional MXene materials is limited. Simple MXene sheets are insufficient in chemical passivation of specific defects on the perovskite surface, and cannot fully eliminate recombination centers. Moreover, its work function lacks precise control methods, making it difficult to achieve optimal energy level alignment with SnO2 and perovskite materials, thus limiting the optimization effect of interface charge transport. Thirdly, organic small molecule passivation schemes have performance contradictions. Although organic small molecules containing specific functional groups can effectively passivate uncoordinated Pb, they also have limitations. 2+ While combining these methods can achieve defect passivation, most organic molecules themselves have poor conductivity. Their introduction would significantly increase the charge transport resistance at the interface, thereby reducing electron transport efficiency and failing to meet the dual core requirements of defect passivation and efficient charge transport.

[0005] In conclusion, a new technical solution is urgently needed to address the problems existing in the current technology. Summary of the Invention

[0006] To address the shortcomings and deficiencies of the existing technologies, this invention provides a fluorescent molecule-modified MXene material, its preparation method, and its application in perovskite solar cells. This invention anchors fluorescent molecules to the MXene surface and the perovskite interface through chemical interaction. This not only directly passivates defects but also, through the synergistic effect of its conjugated structure and MXene, modulates the overall work function of the composite material, making it more perfectly matched to the energy levels of SnO2 and perovskite. This achieves a "ladder" arrangement of energy levels while passivating defects, promoting unobstructed electron transport. Simultaneously, the ultraviolet fluorescence properties of the fluorescent molecules may also enhance the device's utilization of sunlight through fluorescence effects.

[0007] The first objective of this invention is to provide a fluorescent molecule-modified MXene material, wherein the fluorescent molecule-modified MXene material is obtained by reacting fluorescent molecules with MXene material; The fluorescent molecule is an organic conjugated molecule with ultraviolet fluorescence properties, and its molecular structure contains functional groups that can interact with the surface groups of MXene materials.

[0008] Specifically, the fluorescent molecule has ultraviolet fluorescence properties and contains uncoordinated Pb in the perovskite. 2+ Organic conjugated molecules of functional groups that are bound by halogen vacancy defects.

[0009] Specifically, the MXene material is a two-dimensional transition metal carbide or nitride material.

[0010] Further, the fluorescent molecule is selected from one or more of the following: sodium 2,2'-([1,1'-biphenyl]-4,4'-dimethyldiethylene)-bisbenzenesulfonate, tetraphenylethylene, benzophenone-2,9-anthracarboxylic acid, perylene-3,4,9,10-tetracarboxylic acid dianhydride, 1-naphthoic acid, 2,3-naphthoic acid, anthraquinone-2-carboxylic acid, 1-pyrene sulfonic acid, 1,5-naphthoic acid, pyrene-1-sulfonic acid, disodium 2',4',5',7'-tetraiodofluorescein, 3,6-diaminoacridine, 4-amino-1,8-naphthodicarboximide, 7-hydroxycoumarin, 1,2-dihydroxyanthraquinone, and their derivatives.

[0011] Furthermore, the general formula of the MXene material is M n+1 X n T x ; Wherein, M is selected from one or more of Ti, Sc, Y, Zr, Hf, V, Nb, Ta, Cr, Mo, and W; X is C or N; n is any number from 1 to 4; T is a terminal functional group; T is selected from one or more of -OH, =O, =S, =Se, =Te, -Br, -Cl, and -F; x is the number of terminal functional groups, and 0 <x≤2。

[0012] Preferably, the MXene material is Ti3C2T. x , where T is a surface end group such as -OH, -F, =O, etc., and its precursor is Ti3AlC2MAX phase powder.

[0013] Furthermore, the method for preparing the MXene material includes the following steps: Ti3AlC2 was added to the etching solution, heated and stirred to react, and purified to obtain multilayer Ti3C2T. x ; Multilayer Ti3C2T x The mixture was dispersed in an intercalating agent for intercalation treatment, followed by ultrasonic exfoliation at low temperature. The supernatant was collected by centrifugation to obtain an aqueous solution of MXene, which was then dried to obtain the MXene material.

[0014] A second objective of this invention is to provide a method for preparing the fluorescently modified MXene material, the method comprising the following steps: In a solvent, fluorescent molecules are blended with MXene materials, stirred, and purified to obtain fluorescently modified MXene materials.

[0015] Furthermore, the mass ratio of the fluorescent molecule to the MXene material is 1:(1-10).

[0016] A third objective of this invention is to provide an application of the fluorescent molecule-modified MXene material in perovskite solar cells.

[0017] Furthermore, the perovskite solar cell comprises, from bottom to top, a transparent conductive substrate, an electron transport layer, an interface modification layer, a perovskite active layer, and an electrode. The raw material for the interface modification layer includes fluorescent molecule-modified MXene material.

[0018] Furthermore, the thickness of the interface modification layer is 5-50 nm.

[0019] Furthermore, the fabrication method of the perovskite solar cell includes the following steps: S1. SnO2 is coated onto the surface of a transparent conductive substrate and annealed to obtain an electron transport layer. S2. The fluorescent molecule-modified MXene material is coated onto the surface of the electron transport layer and annealed to obtain the interface modification layer. S3. Coat the perovskite material onto the surface of the interface modification layer, add antisolvent, heat, and then anneal at the adjusted temperature to obtain the perovskite active layer. S4. Coat the surface of the perovskite active layer with conductive carbon paste and anneal to obtain a perovskite solar cell with an interface modification layer of MXene material containing fluorescent molecules.

[0020] Furthermore, in step S1, the annealing temperature is 130-170°C.

[0021] Furthermore, in step S2, the annealing temperature is 80-120℃.

[0022] Further, in step S3, the heating temperature is 30-40℃; the annealing temperature is 140-180℃.

[0023] Furthermore, in step S4, the annealing temperature is 100-140°C.

[0024] Specifically, the interface modification layer improves battery performance in the following ways: 1. Fluorescent molecules and MXene synergistically passivate interfacial defects under perovskite, reducing nonradiative recombination; 2. Optimize the energy level arrangement at the interface to promote electron transport; 3. The fluorescence properties of fluorescent molecules enhance the light absorption of the perovskite layer.

[0025] Specifically, compared to the unmodified control battery, the photoelectric conversion efficiency of the battery was improved by 30% after the fluorescent molecule-modified MXene interface modification layer was introduced.

[0026] The present invention has the following beneficial effects: This invention provides a fluorescently modified MXene material, its preparation method, and its application in perovskite solar cells. The fluorescently modified MXene material is obtained by reacting fluorescent molecules with MXene material. When applied as an interface modification layer in perovskite solar cells, the fluorescent molecules provide polar functional groups, effectively passivating ionic defects at the perovskite interface. Simultaneously, their interaction with MXene alters the work function of the composite material, creating a better energy level gradient between SnO2 and perovskite, lowering the electron extraction barrier, and improving the open-circuit voltage and fill factor. Furthermore, the ultraviolet fluorescence properties of the fluorescent molecules can convert some of the absorbed ultraviolet-visible light into wavelengths with higher absorption efficiency in perovskite, or indirectly enhance the light absorption and utilization of the active layer through fluorescence resonance energy transfer effects. Finally, the highly conductive MXene framework provides a fast electron transport channel, overcoming the poor conductivity of pure organic passivators, improving charge collection efficiency, and thus increasing short-circuit current density. The preparation method provided by this invention is simple, low-cost, and has potential for large-scale application. Attached Figure Description

[0027] Figure 1 The chemical structure of the fluorescent molecule CBS used in Examples 1-3 is shown.

[0028] Figure 2 A schematic diagram of the device structure of the perovskite solar cells prepared in Application Examples 1-3 is shown.

[0029] Figure 3 The current density-voltage characteristic curves of the perovskite solar cells prepared in Application Examples 1-3 and Comparative Application Examples 1-2 are shown.

[0030] Figure 4 The graphs showing the dependence of open-circuit voltage on incident light intensity for the perovskite solar cells prepared in Application Examples 1-3 and Comparative Application Example 1-2 are illustrated.

[0031] Figure 5 The current density-voltage characteristic curves of the perovskite solar cells prepared in Application Examples 1-3 and Comparative Application Examples 1-2 are shown in the dark. Detailed Implementation

[0032] To more clearly illustrate the technical solution of the present invention, the following embodiments are provided. 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.

[0033] The terms "preferred," "more preferably," and "more suitable" 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.

[0034] 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.

[0035] In the embodiments, application examples and comparative examples, the following raw materials will be used: Fluorescent molecule CBS: Sodium 2,2'-([1,1'-biphenyl]-4,4'-dimethyldiethylene)-bisbenzenesulfonate, purity ≥97%, purchased from Aladdin.

[0036] MXene material, specifically Ti3C2T x The preparation method for solid powder includes the following steps: 1 g of Ti3AlC2 powder was slowly added to 30 mL of a mixed etching solution (prepared by mixing 20 mL of 9 M hydrochloric acid and 10 mL of 40 wt% hydrofluoric acid). The mixture was stirred in a water bath at 35 °C for 24 h. After the reaction, the supernatant was repeatedly washed by centrifugation with water until the pH was >6. The supernatant was then dispersed in dimethyl sulfoxide for intercalation, followed by ultrasonic exfoliation under ice bath and argon protection for 1 h. Finally, the mixture was centrifuged at 3500 rpm for 1 h, and the supernatant was collected to obtain an MXene aqueous solution. The MXene aqueous solution was freeze-dried to obtain Ti3C2T. x Solid powder.

[0037] ITO glass with a resistivity of 15 Ω, purchased from Liaoning Youxuan, is 1.1 mm thick and has a 15 Ω etching. 15 mm ITO glass.

[0038] SnO2 colloidal aqueous solution with a concentration of 15 wt% was purchased from Alfa Aesa and diluted to 2.5 wt% with deionized water before use.

[0039] Conductive carbon paste, with carbon as filler and a solid content of 40-50 wt%, the remaining components being low-temperature curing thermoplastic resin, purchased from Guangzhou Saidi Technology, model DD-10.

[0040] Perovskite precursor solution: Using a 4:1 volume ratio mixture of dimethylformamide and dimethyl sulfoxide as a solvent, CsI, PbI2, and PbBr2 are dissolved in the solvent at a molar ratio of 2:1:1 to obtain a perovskite precursor solution.

[0041] Unless otherwise specified, the water used in the embodiments and application examples of this invention refers to deionized water.

[0042] Example 1 A fluorescently modified MXene material, wherein the fluorescently modified MXene material is composed of fluorescent molecule CBS and MXene material Ti3C2T. x The product obtained from the reaction.

[0043] The preparation method of the fluorescent molecule-modified MXene material includes the following steps: 10.0 mg of Ti3C2T x The solid powder was dispersed in 5 mL of anhydrous ethanol to obtain a uniform MXene ethanol dispersion; then 1.0 mg of fluorescent molecule CBS was dissolved in 5 mL of anhydrous ethanol to obtain a CBS ethanol solution. Under magnetic stirring, the CBS ethanol solution was added dropwise to the MXene ethanol dispersion, and the reaction was carried out at room temperature for 8 h. After the reaction was completed, the mixture was centrifuged at 4000 rpm for 30 min, the supernatant was discarded, the precipitate was washed twice with ethanol, and dried to obtain the fluorescent molecule modified MXene material.

[0044] Example 2 A fluorescently modified MXene material, wherein the fluorescently modified MXene material is composed of fluorescent molecule CBS and MXene material Ti3C2T. x The product obtained from the reaction.

[0045] The preparation method of the fluorescent molecule-modified MXene material includes the following steps: 5.0 mg of Ti3C2T x The solid powder was dispersed in 5 mL of anhydrous ethanol to obtain a uniform MXene ethanol dispersion; then 1.0 mg of fluorescent molecule CBS was dissolved in 5 mL of anhydrous ethanol to obtain a CBS ethanol solution. Under magnetic stirring, the CBS ethanol solution was added dropwise to the MXene ethanol dispersion, and the reaction was carried out at room temperature for 8 h. After the reaction was completed, the mixture was centrifuged at 4000 rpm for 30 min, the supernatant was discarded, the precipitate was washed twice with ethanol, and dried to obtain the fluorescent molecule modified MXene material.

[0046] Example 3 A fluorescently modified MXene material, wherein the fluorescently modified MXene material is composed of fluorescent molecule CBS and MXene material Ti3C2T.x The product obtained from the reaction.

[0047] The preparation method of the fluorescent molecule-modified MXene material includes the following steps: 1.0 mg of Ti3C2T x The solid powder was dispersed in 5 mL of anhydrous ethanol to obtain a uniform MXene ethanol dispersion; then 1.0 mg of fluorescent molecule CBS was dissolved in 5 mL of anhydrous ethanol to obtain a CBS ethanol solution. Under magnetic stirring, the CBS ethanol solution was added dropwise to the MXene ethanol dispersion, and the reaction was carried out at room temperature for 8 h. After the reaction was completed, the mixture was centrifuged at 4000 rpm for 30 min, the supernatant was discarded, the precipitate was washed twice with ethanol, and dried to obtain the fluorescent molecule modified MXene material.

[0048] Figure 1 The chemical structure of the fluorescent molecule CBS used in Examples 1-3 is shown.

[0049] Application Example 1 A perovskite solar cell, comprising, from bottom to top, a transparent conductive substrate (1.1 mm), an electron transport layer (20 nm), an interface modification layer (25 nm), a perovskite active layer (280 nm), and an electrode (30 μm).

[0050] The method for preparing the perovskite solar cell includes the following steps: S1. Clean the ITO glass with detergent, deionized water, acetone and isopropanol in sequence, and dry it with nitrogen. Treat it under ozone atmosphere and ultraviolet light irradiation for 15 min. Then spin-coat 35 µL of SnO2 colloidal aqueous solution (2.5 wt%) on the ITO glass surface at 3000 rpm for 30 s. Then anneal it on a hot stage at 150℃ for 15 min to obtain the electron transport layer. S2. Disperse 0.5 mg of the fluorescent molecule-modified MXene material from Example 1 in 10 mL of ethanol to obtain a fluorescent molecule-modified MXene material dispersion; spin-coat 40 µL of the fluorescent molecule-modified MXene material dispersion onto the surface of the electron transport layer at 3000 rpm for 30 s, and then anneal it on a hot plate at 100°C for 10 min to form an interface modification layer. S3. Spin-coat 35 µL of perovskite precursor solution onto the surface of the interface modification layer at 1000 rpm for 10 s, then accelerate to 4000 rpm for 30 s, and add 100 μL of isopropanol at the 20th s. Then heat on a hot stage at 35°C for 90 s, adjust the temperature to 160°C and heat for 10 min to obtain the perovskite active layer. S4. Take two polyimide insulating tapes of appropriate width and paste them parallel to each other on the areas not covered by the functional layer on both sides of the ITO conductive glass substrate. These serve as the boundary and thickness reference for the coating process. The area between the two tapes is the electrode forming area. Using a scraper, apply an appropriate amount of conductive carbon paste to the surface of the perovskite active layer, based on the thickness of the insulating tape. Anneal at 120°C for 10 minutes to form the electrode, thus obtaining the perovskite solar cell.

[0051] Application Example 2-3 The preparation methods of Application Examples 2-3 are the same as those of Application Example 1, except that the fluorescent molecule-modified MXene materials used in step S2 are prepared by Example 2-3 respectively.

[0052] Figure 2 A schematic diagram of the device structure of the perovskite solar cells prepared in Application Examples 1-3 is shown.

[0053] Comparative Application Example 1 The difference between this comparative application example and application example 1 is that step S2 is omitted, and step S3 is modified as follows: S3. Spin-coat 35 µL of perovskite precursor solution onto the electron transport layer surface at 1000 rpm for 10 s, then accelerate to 4000 rpm for 30 s, and add 100 μL of isopropanol at the 20th s. Then heat on a hot stage at 35℃ for 90 s, adjust the temperature to 160℃ and heat for 10 min to obtain the perovskite active layer. The other steps and dosages are the same as in Application Example 1.

[0054] Comparative Application Example 2 The difference between this comparative application example and application example 1 is that the fluorescent molecule-modified MXene material in step S2 is replaced with an equal mass of MXene material, while the other steps and amounts are the same as in application example 1.

[0055] Test case Performance tests were conducted on the perovskite solar cells prepared in the corresponding use cases 1-3 and in comparison with those prepared in application example 1-2.

[0056] Test Method: Under standard AM 1.5G illumination, the fabricated device was subjected to current density-voltage testing. The test was conducted using the SS-F5-3A series solar simulator from Guangyan Company, which provided AM 1.5G (100 mW / cm²). 2 The fabricated devices were irradiated with a spectral irradiation spectrum, and voltage scans (scan range: -0.1 to 1.2 V, step size 10 mV, delay of 100 ms per point) were performed using a Keithley 2400 series digital source meter, and current density was recorded. Current density-voltage measurements were then performed on the fabricated devices under dark conditions using the same parameters.

[0057] The results are shown in Table 1. Figure 3-5 As shown.

[0058] Table 1 Performance Test Results Figure 3 The current density-voltage characteristic curves of the perovskite solar cells prepared in Application Examples 1-3 and Comparative Application Example 1-2 are shown. Figure 3 It can be seen that the device with the CBS-MXene composite interface modification layer (Example 1) exhibits a significantly larger area enclosed by its JV curve (corresponding to the photoelectric conversion efficiency PCE) than the devices without the interface modification layer (Comparative Example 1) and those with only the pure MXene modification layer (Comparative Example 2). Specifically, the device in Example 1 has the highest open-circuit voltage (Voc), short-circuit current density (Jsc), and fill factor (FF). This demonstrates that the CBS-MXene composite layer has a significant effect on improving the overall photovoltaic performance of the device.

[0059] Figure 4 The graphs show the dependence of open-circuit voltage on incident light intensity for perovskite solar cells fabricated in Application Examples 1-3 and Comparative Application Example 1-2. Typically, the relationship between open-circuit voltage (Voc) and light intensity follows the formula: Voc = (nKT / q)ln(I) + constant, where the slope nKT / q is a key parameter for determining the dominant recombination mechanism in the device. The closer the ideality factor n is to 1, the closer the device is to an ideal state dominated by radiative recombination; the larger the value of n, the more significant the non-radiative recombination assisted by defects / traps. Figure 4 As shown, Example 1 exhibits the smallest slope, with an n value of only 1.05 KT / q, extremely close to the ideal radiative recombination limit (1 KT / q). Examples 2-3 also possess relatively low ideality factors of 1.15 KT / q and 1.25 KT / q, respectively. In contrast, Comparative Examples 2 and 1 have n values ​​as high as 1.39 KT / q and 1.77 KT / q, respectively. This result provides decisive evidence that the fluorescent molecule-modified MXene material interface modification layer can passivate defects at the perovskite / electron transport layer interface with extremely high efficiency, and proves that the optimal feed ratio is the ratio used in Application Example 1.

[0060] Figure 5 The current density-voltage characteristic curves of the perovskite solar cells fabricated in Application Examples 1-3 and Comparative Application Example 1-2 are shown under dark conditions. The graph uses a logarithmic scale on the vertical axis, clearly revealing the carrier generation and recombination behavior of the device under reverse bias and low forward bias. Figure 5It can be seen that under low electric field (reverse and low forward bias): the nonradiative recombination of interface defects is strongly suppressed by the chemical passivation effect of CBS molecules, and the leakage current is reduced. The current is even higher under high bias, which shows that the CBS-MXene layer also significantly improves the electron injection and transport capabilities, which is mainly due to the high conductivity of the MXene material itself.

[0061] As shown in Table 1, the present invention can not only significantly improve the photoelectric conversion efficiency of the battery by combining CBS fluorescent molecules with MXene, but also simultaneously optimize the open-circuit voltage, short-circuit current and fill factor, demonstrating the synergistic effect of the composite interface layer in defect passivation, energy level regulation and charge transport promotion.

[0062] 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.

[0063] 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 fluorescently modified MXene material, characterized in that, The fluorescent molecule-modified MXene material is obtained by reacting fluorescent molecules with MXene material; The fluorescent molecule is an organic conjugated molecule with ultraviolet fluorescence properties, and its molecular structure contains functional groups that can interact with the surface groups of MXene materials.

2. The fluorescently modified MXene material according to claim 1, characterized in that, The fluorescent molecule is selected from one or more of the following: sodium 2,2'-([1,1'-biphenyl]-4,4'-dimethyldiethylene)-bisbenzenesulfonate, tetraphenylethylene, benzophenone-2,9-anthracarboxylic acid, perylene-3,4,9,10-tetracarboxylic acid dianhydride, 1-naphthoic acid, 2,3-naphthoic acid, anthraquinone-2-carboxylic acid, 1-pyrene sulfonic acid, 1,5-naphthoic disulfonic acid, pyrene-1-sulfonic acid, disodium 2',4',5',7'-tetraiodofluorescein, 3,6-diaminoacridine, 4-amino-1,8-naphthodicarboximide, 7-hydroxycoumarin, 1,2-dihydroxyanthraquinone, and their derivatives.

3. The fluorescently modified MXene material according to claim 1, characterized in that, The general formula of the MXene material is M n+1 X n T x ; Wherein, M is selected from one or more of Ti, Sc, Y, Zr, Hf, V, Nb, Ta, Cr, Mo, and W; X is C or N; n is any number from 1 to 4; T is a terminal functional group; T is selected from one or more of -OH, =O, =S, =Se, =Te, -Br, -Cl, and -F; x is the number of terminal functional groups, and 0 <x≤2。 4. The method for preparing the fluorescent molecule-modified MXene material according to any one of claims 1-3, characterized in that, The preparation method of the fluorescent molecule-modified MXene material includes the following steps: In a solvent, fluorescent molecules are blended with MXene materials, stirred, and purified to obtain fluorescently modified MXene materials.

5. The method for preparing fluorescently modified MXene materials according to claim 4, characterized in that, The mass ratio of the fluorescent molecule to the MXene material is 1:(1-10).

6. The application of the fluorescent molecule-modified MXene material according to any one of claims 1-3 in perovskite solar cells.

7. The application of the fluorescent molecule-modified MXene material according to claim 6 in perovskite solar cells, characterized in that, The perovskite solar cell comprises, from bottom to top, a transparent conductive substrate, an electron transport layer, an interface modification layer, a perovskite active layer, and an electrode; The raw material for the interface modification layer includes MXene material modified with fluorescent molecules.

8. The application of the fluorescent molecule-modified MXene material according to claim 7 in perovskite solar cells, characterized in that, The thickness of the interface modification layer is 5-50 nm.

9. The application of the fluorescent molecule-modified MXene material according to claim 6 in perovskite solar cells, characterized in that, The method for preparing the perovskite solar cell includes the following steps: S1. SnO2 is coated onto the surface of a transparent conductive substrate and annealed to obtain an electron transport layer. S2. The fluorescent molecule-modified MXene material is coated onto the surface of the electron transport layer and annealed to obtain the interface modification layer. S3. Coat the perovskite material onto the surface of the interface modification layer, add antisolvent, heat, and then anneal at the adjusted temperature to obtain the perovskite active layer. S4. Coat the surface of the perovskite active layer with conductive carbon paste and anneal to obtain a perovskite solar cell with an interface modification layer of MXene material containing fluorescent molecules.

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