A porphyrin-passivated perovskite nanofilm material and its preparation and application

Abstract

The present invention relates to a porphyrin-passivated perovskite nanofilm material and its preparation and application. The porphyrin-passivated perovskite nanofilm material comprises a perovskite material and a porphyrin molecule for passivating the perovskite material. The porphyrin molecule has an alkoxy solubilizing group, and an aniline group, a benzoic acid group, or both are connected to the meso position of the porphyrin via a π-conjugated acetylene bridge, thereby obtaining a porphyrin molecule with a passivating effect. By introducing the molecule and effectively coordinating and bonding with the perovskite defect sites, a functionalized perovskite nanofilm material is prepared. Compared with the prior art, the porphyrin-passivated perovskite nanofilm material of the present invention exhibits significantly improved excellent nonlinear absorption performance under nanosecond laser excitation in a wide wavelength range. The preparation method is simple to operate, low-cost, and applicable to perovskite materials with multiple defect problems, providing a feasible example for the development of such new photonic materials.

Description

Technical Field

[0001] The present invention relates to the technical field of nonlinear optical materials, and in particular to a porphyrin-passivated perovskite nano-film material and its preparation and application. Background Art

[0002] After long-term development, organic-inorganic hybrid perovskite materials have important application value in the field of optoelectronics. It is a new type of optical functional material with the general formula ABX3, where A represents a monovalent cation, such as MA + , GA + , FA + ; B is a metal ion, such as divalent Pb 2 + and Sn 2+ , monovalent Ag + and Bi + ; X is a halogen atom, such as Cl - , Br - , I - In recent years, the excellent optoelectronic properties of perovskites, including high absorption coefficient, tunable band gap, high carrier mobility and large oscillator strength, have enabled researchers to see their potential in the development of nonlinear photonic devices. For example, Zhang et al. reported a high-quality, low-intrinsic-bandgap CH3NH3Pb 0.75 Sn 0.25 I3 perovskite films with an absorption edge at 910 nm. These films can demonstrate 1.15 cm kW at wavelengths compatible with optical communication wavelengths (OCWB). -1 The ultra-large nonlinear absorption coefficient can realize the application of direct infrared photodetection devices with good performance at 1535nm (Xie, Y.; Fan, J.; Liu, C.; Chi, S.; Wang, Z.; Yu, H.; Zhang, H.; Mai, Y.; Wang, J., Giant two-photon absorption in mixed halideperovskite CH3NH3Pb0.75Sn0.25I3 thin films and application to photodetection at optical communication wavelengths. Advanced Optical Materials 2018, 6, 1700819.).

[0003] Although perovskites have excellent optoelectronic properties, various ionic defects generated during the crystallization process have hindered the further development of perovskites, such as I -Positive vacancy defects caused by loss and negative vacancy defects caused by the escape of organic cations. These defects easily generate various trap states that capture normal electrons, hindering the transport of carriers, thereby leading to non-radiative charge recombination and energy loss. In addition, these defects can also allow air and water from the external environment to penetrate into the perovskite lattice, inducing degradation of the inorganic octahedral lattice of the perovskite, thereby leading to the deterioration of the perovskite's optoelectronic properties, especially its nonlinear optical properties. Therefore, resolving perovskite defects, especially improving the structural stability and optoelectronic properties of perovskites through the multifunctional regulation of perovskite defects, has become an urgent issue to be addressed in the development of such photonic materials and the construction of high-performance perovskite-based photonic devices.

[0004] Patent Publication No. CN113921722A discloses a porphyrin-modified organic-inorganic hybrid perovskite nanofilm material and its preparation method, which utilizes porphyrin molecules containing carboxyl and amino functional groups to modify organic-inorganic hybrid perovskites, and interacts with the defect sites contained in the perovskite structure through the specific functional groups of the porphyrin molecules to make functionalized nanofilm materials. However, each porphyrin can only passivate a single type of perovskite defect individually, lacking multifunctional regulation of different types of perovskite defects. In addition, the tetraphenylporphyrin derivative structure disclosed in the patent lacks a π-conjugated connecting bridge (acetylene group), so when the molecule connects the perovskite components on both sides of the grain boundary through passivation, it cannot achieve efficient charge transfer, which is not conducive to the improvement of the material's nonlinear optical absorption performance; at the same time, its planarity and π-conjugation effect are low, so the suppression effect on neutral iodine (I2) defects in the perovskite is poor. Summary of the Invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and provide a porphyrin-passivated perovskite nano-thin film material and its preparation and application, effectively repair perovskite defects and improve the nonlinear optical properties of perovskite nano-hybrid materials.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] One of the technical solutions of the present invention provides a porphyrin-passivated perovskite nanofilm material, which is composed of a perovskite material and a porphyrin molecule for passivating the perovskite material. The aniline groups and / or benzoic acid groups connected by acetylene groups at the meso positions on both sides of the porphyrin form bonds with uncoordinated halogen anions and / or uncoordinated metal cations in the perovskite. The general structural formula of the porphyrin molecule is as follows:

[0008]

[0009] Wherein, R1 and R2 are amino or carboxyl groups.

[0010] Furthermore, the general formula of the perovskite material is ABX3, wherein A is a monovalent organic cation MA + , B is a divalent metal cation Pb 2+ , X is a halogen monovalent anion I ﹣ .

[0011] Furthermore, the aniline groups and / or benzoic acid groups connected to the meso positions on both sides of the porphyrin molecule form bonds with uncoordinated halogen anions and / or uncoordinated metal cations in the perovskite material.

[0012] Furthermore, the porphyrin molecule is 5,15-bis(2,6-dihexyloxyphenyl)-10,20-bis(4-aminophenylethynyl)porphyrin (POR1, corresponding to R1=R2=NH2), 5,15-bis(2,6-dihexyloxyphenyl)-10,20-bis(4-carboxyphenylethynyl)porphyrin (POR2, corresponding to R1=R2=COOH) or 5,15-bis(2,6-dihexyloxyphenyl)-10-(4-aminophenylethynyl)-20-(4-carboxyphenylethynyl)porphyrin (POR3, corresponding to R1=COOH, R2=NH2).

[0013] Furthermore, the general synthesis route of the porphyrin molecule is as follows:

[0014]

[0015] The second technical solution of the present invention provides a method for preparing a porphyrin-passivated perovskite nanofilm material, comprising the following steps:

[0016] S1: Prepare a perovskite precursor solution containing lead iodide (PbI2) and methylammonium iodide (MAI);

[0017] S2: preparing an antisolvent containing porphyrin molecules;

[0018] S3: spin-coating the perovskite precursor solution and the anti-solvent containing porphyrin molecules on a substrate to form a film, and then annealing to obtain a target material.

[0019] Furthermore, in step S1, the mass ratio of PbI2 and MAI in the perovskite precursor solution is (2-4):1.

[0020] Furthermore, in step S1 , the solvent used in the perovskite precursor solution is a mixture of ultra-dry N,N-dimethylformamide (DMF) and ultra-dry dimethyl sulfoxide (DMSO).

[0021] Furthermore, the mass ratio of the ultra-dry DMF to the ultra-dry DMSO is (4-10):1.

[0022] Furthermore, in step S2, the antisolvent is chloroform, and the concentration of the added porphyrin molecules is 0.2 to 0.5 mg / mL -1 .

[0023] Furthermore, in step S3, the spin coating process is specifically as follows: dropping the perovskite precursor solution onto the substrate, spin coating at a low speed to form a film, and then adding an anti-solvent containing porphyrin during high-speed spin coating until a bright film is formed.

[0024] Furthermore, the low-speed spin coating has a rotation speed of 1100-1500 rpm, and the high-speed spin coating has a rotation speed of 5000-6000 rpm.

[0025] Furthermore, the spinning time of the low-speed spin coating is 10 to 15 seconds, the spinning time of the high-speed spin coating is 20 to 40 seconds, and the anti-solvent is added during the 10th to 20th second of the high-speed spinning.

[0026] Furthermore, in step S3, the substrate includes a quartz sheet, a common glass sheet, an indium tin oxide (ITO) glass sheet, or a fluorine-doped tin oxide (FTO) glass sheet.

[0027] Furthermore, in step S3, the volume ratio of the perovskite precursor solution to the anti-solvent containing porphyrin molecules is 1:4-8.

[0028] Furthermore, in step S3, the substrate is first washed multiple times with detergent and deionized water, then ultrasonically cleaned with acetone, deionized water, and isopropyl alcohol for 2 to 10 minutes each, and then dried in an oven for at least 5 hours. The substrate is then treated with a vacuum oxygen plasma treatment system for 5 to 10 minutes, and then cooled to room temperature before use.

[0029] Furthermore, in step S3, the annealing temperature is 85-100° C., and 95° C. may be selected; and the annealing time is 10-15 minutes, and 10 minutes may be selected.

[0030] Furthermore, steps S1, S2, and S3 are all performed at room temperature and in a dry air environment.

[0031] A third technical solution of the present invention provides an application of a porphyrin-passivated perovskite nanofilm material in the field of nonlinear optical material technology.

[0032] The porphyrin-passivated perovskite film prepared by the present invention has a smooth, dense, and lustrous surface and exhibits significantly enhanced, excellent nonlinear optical absorption properties. Under 1064nm nanosecond laser irradiation, the nonlinear absorption coefficient of the material is 3.6 to 10 times greater than that of the original perovskite film, an increase of nearly an order of magnitude. Under 532nm nanosecond laser excitation, it also shows a 2.7 to 4-fold increase. The mechanism is that the porphyrin molecules with amino or carboxyl groups have good planarity (i.e., a π-planar conjugated structure) and the acetylene π-conjugated bridge connects the passivating groups. Therefore, in the process of passivating perovskite defects, efficient charge transfer channels can be constructed at the perovskite grain boundaries, thereby promoting charge transfer between the porphyrin and the perovskite during light excitation. Furthermore, the amino functional groups and carboxyl functional groups on both sides of the meso position of the porphyrin molecule can respectively produce coordination interactions (i.e., bond formation) with the uncoordinated iodide ions and uncoordinated lead ions in the perovskite. Porphyrin, which has both types of functional groups, can simultaneously passivate both types of defects, minimize the density of trap states, and repair defects. This improves the stability of the perovskite structure, enhances the carrier absorption and Pauli blocking effect of the material, and thus produces optimal nonlinear optical absorption performance. In addition, the carrier mobility of the perovskite material passivated by porphyrin is improved, which enhances the nonlinear absorption; and the dual-functional passivation effect between porphyrin and perovskite also drives effective charge / energy transfer, which can synergistically enhance the nonlinear optical properties of the material. Therefore, the perovskite film modified by porphyrin passivation can exhibit very competitive nonlinear optical properties.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] (1) The preparation method of the porphyrin-passivated perovskite nano-film material of the present invention can obtain a smooth and flat film, which can be applied to most defective perovskite materials and has a wide range of applications.

[0035] (2) The preparation method of the porphyrin-passivated perovskite nano-film material of the present invention can be carried out in an air environment, saves materials, is low in cost, has a convenient preparation process, and is easy to operate.

[0036] (3) The porphyrin molecules used in the present invention have good solubility and are suitable for preparing perovskite thin film materials by large-scale solution deposition method.

[0037] (4) The porphyrin-passivated perovskite film produced by the present invention has a significantly improved stability compared to the original perovskite film. Under a 1064nm nanosecond laser, its nonlinear absorption coefficient is 3.6 to 10 times that of the unmodified film, and under a 532nm nanosecond laser, the nonlinear absorption coefficient of the modified perovskite film is 2.7 to 4 times that of the unmodified film. This is due to the good planarity (i.e., π-plane conjugated structure) of the porphyrin molecules with amino groups or carboxyl groups, and the acetylene π-conjugated bridge connecting the passivating groups. Therefore, in the process of passivating the perovskite defects, an efficient charge transfer channel can be constructed at the perovskite grain boundary, thereby promoting the charge transfer between porphyrin and perovskite during the light excitation process, thereby showing significantly enhanced nonlinear optical absorption performance. The nonlinear optical performance of the perovskite material passivated by porphyrin with bifunctional functional groups is the best among many materials, showing excellent application potential in a wide band and wide time domain. This invention shows that the unique dual-functional passivation strategy of porphyrin can overcome the disadvantage of insufficient nonlinear optical performance of perovskite materials, and provides a new reference for constructing efficient photonic devices using defect modulation strategies. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Schematic diagram of the bonding process of porphyrin passivation perovskite defects prepared by the present invention;

[0039] Figure 2 X-ray diffraction patterns of the porphyrin-passivated perovskite film prepared by the present invention and the original film;

[0040] Figure 3 Scanning electron microscope images of the porphyrin-passivated perovskite film prepared by the present invention and the original film;

[0041] Figure 4 X-ray photoelectron spectra of Pb, I, and O elements of the porphyrin-passivated perovskite film prepared by the present invention and the original film;

[0042] Figure 5 The fluorescence spectra and time-resolved fluorescence spectra of the porphyrin-passivated perovskite film and the original film prepared by the present invention;

[0043] Figure 6 These are the open-pore Z-scan curves of the porphyrin-passivated perovskite film prepared in the present invention and the original film under 1064 nm and 532 nm nanosecond laser excitation, respectively. DETAILED DESCRIPTION

[0044] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0045] In the following examples, the nonlinear optical absorption properties of various porphyrin-passivated perovskite nanofilm materials were tested using an aperture Z-scanning device under visible and near-infrared nanosecond lasers. The laser used in the aperture Z-scanning device was a Q-switched YAG:Nd3+ nanosecond laser (LS-2145-OPO-PC) developed and produced by LOTIS TII, Belarus, with an output wavelength of 532 nm, a pulse width of 14 ns, and a repetition rate of 10 Hz.

[0046] It should be noted that the perovskite raw material methylammonium iodide (MAI) used in the following examples was prepared in the laboratory, and the preparation method is as follows:

[0047] Equimolar amounts of methylamine (40 wt.% methanol solution) and hydroiodic acid (57 wt.% aqueous solution) were stirred at 0°C for 1 hour, followed by rotary evaporation at 50°C for 1 hour. The crude product was filtered, washed three times with 150 mL of ether, and dried under vacuum at 60°C for several days to obtain a white powdery solid, methylammonium iodide.

[0048] In the following examples, the synthesis methods of 2,2'-dipyrrolylmethane (Compound 3) and 2,6-dihexyloxybenzaldehyde (Compound 5) used are all based on existing technologies:

[0049]

[0050] References:

[0051] 1. Plater, MJ; Aiken, S.; Bourhill, G., A new synthetic route to donor–acceptor porphyrins. Tetrahedron 2002, 58(12), 2405-2413.

[0052] 2. Greaves, CR; Alemán García, M. Bampos,N.,Preparation of aporphyrinic bis(pyridyl aldehyde)and its supramolecular complexes.ChemicalCommunications 2015,51(86),15689-15691.

[0053] Unless otherwise specified, the remaining raw materials or processing techniques are conventional commercially available raw materials or conventional processing techniques in the art.

[0054] Example 1

[0055] (1) Synthesis of 5,15-bis(2,6-dihexyloxyphenyl)-10,20-bis(4-aminophenylethynyl)porphyrin (POR1)

[0056]

[0057] Synthesis of 5,15-bis(2,6-dihexyloxyphenyl)porphyrin (Compound 6):

[0058] Dipyrromethene (6.04 g, 41.4 mmol) and 2,6-dihexyloxybenzaldehyde (15 g, 41.4 mmol) were dissolved in 5.4 L of dichloromethane and degassed at room temperature under a nitrogen atmosphere for 30 minutes. Trifluoroacetic acid (2.75 mL, 37.3 mmol) was then quickly added, and the mixture was stirred for 4 hours in the dark. 2,3-Dichloro-5,6-dicyano-p-benzoquinone (14.1 g, 62.1 mmol) was then added to the mixture and allowed to react for 1 hour. After completion of the reaction, the mixture was quenched with triethylamine, and the crude product solution was passed through a flash chromatography column and dried over anhydrous sodium sulfate. The solvent was removed under reduced pressure, and the product was purified by silica gel chromatography using a mixture of dichloromethane and petroleum ether (1:2, v / v) as the eluent to obtain compound 6. The yield was 2.63 g, or 15%.

[0059] 1 H NMR(600MHz,Chloroform-d)δ10.14(s,2H),9.26(d,J=4.4Hz,4H),8.97(d,J=4.4Hz,4H),7.70(t,J=8.5Hz,2H),7.0 2(d,J=8.6Hz,4H),3.83(t,J=6.4Hz,8H),0.90(m,8H),0.51(m,16H),0.41(m,8H),0.26–0.21(m,12H),-3.02(s,2H).

[0060] Synthesis of 5,15-bis(2,6-dihexyloxyphenyl)-10,20-dibromoporphyrin (Compound 7):

[0061] Compound 6 (0.4 g, 0.65 mol) was dissolved in 450 mL of dichloromethane and placed in an ice-water bath. N-bromosuccinimide (1.34 g, 7.54 mmol) was then added to the solution at 0°C and stirred under a nitrogen atmosphere for 4 hours. After completion, the reaction was quenched with 30 mL of acetone. The crude product solution was flash chromatographed and dried over anhydrous sodium sulfate. The solvent was removed under reduced pressure, and the product was purified by silica gel chromatography using a mixture of dichloromethane and petroleum ether (1:3, v / v) as the eluent. Finally, the product was recrystallized from dichloromethane and methanol to afford compound 7. The yield was 2.3 g (61%).

[0062] 1 H NMR(600MHz,Chloroform-d)δ10.01(s,1H),9.62(d,J=4.6Hz,2H),9.17(d,J=4.3Hz,2H),8.88(t,J=5.1Hz,4H),7.70(t,J=8.5Hz,2H),7.0 0(d,J=8.6Hz,4H),3.83(t,J=6.3Hz,8H),0.94–0.90(m,8H),0.53–0.49(m,16H),0.41–0.38(m,8H),0.23(t,J=6.8Hz,12H),-2.88(s,2H).

[0063] Synthesis of 5,15-bis(2,6-dihexyloxyphenyl)-10,20-bis(4-aminophenylethynyl)porphyrin (POR1):

[0064] Compound 7 (102.1 mg, 0.1 mmol), 4-aminophenylacetylene (23.4 mg, 0.2 mmol), and cuprous iodide (4 mg, 0.02 mmol) were dissolved in a mixture of 15 mL of anhydrous triethylamine and 10 mL of anhydrous N,N-dimethylformamide and degassed under nitrogen for 30 minutes. Tetrakistriphenylphosphine palladium (12 mg, 0.01 mmol) was then added, and the mixture was allowed to react at 80°C for 24 hours. After completion of the reaction, the solvent was removed under reduced pressure, and the crude product was dissolved in dichloromethane and washed sequentially with saturated sodium carbonate solution, deionized water, and brine. The product was then dried over anhydrous sodium sulfate. After removal of the solvent under reduced pressure, the product was purified by silica gel chromatography using a mixture of petroleum ether / dichloromethane / tetrahydrofuran (3:1:0.1, v / v / v) as the eluent. Finally, the product was recrystallized from dichloromethane / methanol to yield compound POR1.

[0065] Yield: 50.3 mg, yield: 46%. 1 H NMR(600MHz,Chloroform-d)δ9.56(d,J=5.2Hz,4H),8.75(d,J=3.7Hz,4H),7.81(d,J=5.2Hz,4H),7.71(t,J=8.5Hz,2H),7.59(d,4H) ,7.01(d,J=8.6Hz,4H),3.95(s,4H),3.86(t,J=6.7Hz,8H),1.02–0.96(m,8H),0.61–0.46(m,24H),0.35–0.24(m,12H),-1.75(s,2H).

[0066] (2) Synthesis of 5,15-bis(2,6-dihexyloxyphenyl)-10,20-bis(4-carboxyphenylethynyl)porphyrin (POR2):

[0067]

[0068] The synthesis of 5,15-bis(2,6-dihexyloxyphenyl)-10,20-bis(4-carboxyphenylethynyl)porphyrin (POR2) ​​followed largely the same steps as those for 5,15-bis(2,6-dihexyloxyphenyl)-10,20-bis(4-aminophenylethynyl)porphyrin (POR1), except that 4-aminophenylethynyl (23.4 mg, 0.2 mmol) was replaced with 4-carboxyphenylethynyl (121.2 mg, 0.2 mmol). The molar ratio of compound 7, 4-carboxyphenylethynyl, cuprous iodide, and palladium tetratriphenylphosphine was adjusted to 1:2:0.2:0.1. Purification by silica gel chromatography was performed using a mixture of petroleum ether and dichloromethane (1:1, v / v) as the eluent. Compound POR2 was obtained in a 57% yield.

[0069] 1 H NMR (600MHz, DMSO-d6) δ9.64(d,J=3.4Hz,4H),8.74(d,J=3.7Hz,4H),8.06(d,J=7.9Hz,4H),7.97(d,J=9.1Hz ,4H),7.79(t,2H),7.16(d,J=7.6Hz,4H),3.92(t,8H),0.97–0.79(m,16H),0.41–0.16(m,28H),-2.00(s,2H).

[0070] (3) Synthesis of 5,15-bis(2,6-dihexyloxyphenyl)-10-(4-aminophenylethynyl)-20-(4-carboxyphenylethynyl)porphyrin (POR3):

[0071]

[0072] Synthesis of 5,15-bis(2,6-dihexyloxyphenyl)-10-(4-aminophenylethynyl)-20-bromoporphyrin (Compound 8):

[0073] Compound 7 (102.1 mg, 0.1 mmol), 4-aminophenylacetylene (6 mg, 0.05 mmol), and cuprous iodide (2 mg, 0.01 mmol) were dissolved in a mixture of 5 mL of anhydrous triethylamine and 5 mL of anhydrous tetrahydrofuran and degassed under nitrogen for 30 minutes. Tetrakistriphenylphosphine palladium (12 mg, 0.01 mmol) was then added, and the reaction was stirred at 75°C for 12 hours. After completion of the reaction, the solvent was removed under reduced pressure, and the crude product was dissolved in dichloromethane. The product was washed sequentially with saturated sodium carbonate solution, deionized water, and brine, and dried over anhydrous sodium sulfate. After removal of the solvent under reduced pressure, the product was purified by silica gel chromatography using a mixture of petroleum ether and dichloromethane (2:1, v / v) as the eluent. Finally, it was recrystallized from dichloromethane / methanol to obtain compound 8. The yield was 53.9 mg, or 51%.

[0074] 1 H NMR(600MHz,Chloroform-d)δ9.59(d,J=4.7Hz,2H),9.49(d,J=4.7Hz,2H),8.78(d,J =4.9Hz,2H),8.76(d,J=4.7Hz,2H),7.82(d,J=8.0Hz,2H),7.71(t,J=8.3Hz,2H),7.0 1(d,J=8.5Hz,4H),6.86(d,J=8.0Hz,2H),3.98(s,2H),3.86(t,J=6.4Hz,8H),1.00–0 .96(m,8H),0.59–0.53(m,16H),0.48–0.42(m,8H),0.30–0.24(m,12H),-2.14(s,2H).

[0075] Synthesis of 5,15-bis(2,6-dihexyloxyphenyl)-10-(4-aminophenylethynyl)-20-(4-carboxyphenylethynyl)porphyrin (POR3):

[0076] The synthesis of 5,15-bis(2,6-dihexyloxyphenyl)-10-(4-aminophenylethynyl)-20-(4-carboxyphenylethynyl)porphyrin (POR3) followed largely the same steps as for 5,15-bis(2,6-dihexyloxyphenyl)-10,20-bis(4-aminophenylethynyl)porphyrin (POR1), except that compound 7 was replaced by compound 8, 4-aminophenylethynyl was replaced by 4-carboxyphenylethynyl, and the molar ratio of compound 8, 4-carboxyphenylethynyl, cuprous iodide, and palladium tetratriphenylphosphine was adjusted to 1:1:5:0.2:0.1. The reaction solvent was adjusted to a mixed solution of anhydrous triethylamine and anhydrous N,N-dimethylformamide by adding 25 mL of anhydrous triethylamine to afford compound POR3 in a 57% yield.

[0077] 1H NMR (400MHz, DMSO-d6) δ9.59(d,J=18.9Hz,4H),8.69(d,J=18.4Hz,4H),8.19(s,4H),7.76(d,J=8.5Hz,4H),7.15(s, 4H), 6.78 (d, J = 8.1Hz, 2H), 3.89 (s, 8H), 1.29–1.08 (m, 10H), 0.97–0.77 (m, 10H), 0.45–0.04 (m, 24H), -1.86 (s, 2H).

[0078] Example 2:

[0079] The porphyrins POR1, POR2, and POR3 synthesized in Example 1 of the present invention were used to passivate the perovskite MAPbI3, resulting in a series of porphyrin-passivated perovskite films, labeled MAPbI3 / POR1, MAPbI3 / POR2, and MAPbI3 / POR3 films, respectively. The nonlinear absorption properties of the materials were tested using an open-aperture Z-scanning device. The specific steps are as follows:

[0080] (1) Weigh 461 mg of PbI2 and 159 mg of MAI into a small sample bottle, add 600 mg of DMF and 78 mg of DMSO to dissolve, then heat to 55 °C and stir overnight to form a perovskite precursor solution. Cool to room temperature before use and filter with a 0.22 μm nylon filter membrane.

[0081] (2) Prepare 0.5 mg mL -1 Porphyrin chloroform solution: Weigh 5 mg of porphyrin molecules and dissolve them in 10 mL of chloroform. Filter with a 0.22 μm nylon filter membrane before use.

[0082] (3) A 0.2 cm × 0.2 cm quartz wafer was used as the substrate. It was cleaned with detergent and deionized water in advance and placed in a beaker. Ultrasonic cleaning was performed with acetone, deionized water, and isopropyl alcohol for 5 minutes each, followed by drying in an oven for at least 5 hours. The wafer was then treated with a vacuum oxygen plasma treatment system for at least 5 minutes and cooled to room temperature.

[0083] (3) Use a pipette to draw 50 μL of perovskite precursor solution, statically drop it on the treated substrate, and spin-coat it at a low speed of 1300 rpm for 12 seconds to form a film. Then, the film is rotated at a high speed of 5500 rpm for 30 seconds. At the 15th second, 300 μL of porphyrin chloroform solution (i.e., antisolvent) is quickly added to the film surface. The spin-coated film is then placed on a 95°C hot plate for annealing for 10 minutes to obtain a series of porphyrin-modified perovskite films. They are labeled as MAPbI3 / POR1, MAPbI3 / POR2, and MAPbI3 / POR3 respectively.

[0084] (4) According to step (3), pure chloroform is added during the anti-solvent addition step, and an unmodified original perovskite film is prepared, which is labeled as MAPbI3.

[0085] Among them, the above steps are all carried out in a dry air environment at room temperature.

[0086] (5) The nonlinear optical absorption properties of four perovskite films under 1064nm and 532nm, 14 nanosecond laser excitation were tested by the open-aperture Z-scan method.

[0087] Figure 1 The schematic diagram of the bonding of porphyrin passivation perovskite defects prepared by the present invention is as follows. The present invention is prepared by bonding the aniline groups or / and benzoic acid groups connected at the meso positions on both sides of the porphyrin with the uncoordinated halogen anions or / and uncoordinated metal cations in the perovskite. Figure 1 As shown, porphyrin molecules containing amino groups can form bonds with uncoordinated iodide anions (negative charge defects caused by the lack of methylamine cations). Porphyrin molecules containing carboxyl groups can form bonds with uncoordinated lead cations in the perovskite (positive charge defects caused by the lack of iodide anions). Porphyrin molecules with both functional groups can form bonds with uncoordinated positive and negative ions in the perovskite, passivating perovskite defects and thereby improving the nonlinear optical properties of the perovskite material.

[0088] Figure 2 The X-ray diffraction patterns of the porphyrin-passivated perovskite film and the original film prepared by the present invention are shown. The XRD patterns of all films have common diffraction peaks at 14.1°, 28.7°, and 32.2°, corresponding to the (110), (220), and (310) crystal planes, respectively. The minimum peak observed at 12.9° is the crystal plane of the PbI2 component. The spectrum without obvious changes indicates that the perovskite film after porphyrin passivation is not affected by the introduction of porphyrin organic macromolecules during the crystallization process and can still show a good crystalline phase.

[0089] Figure 3 Scanning electron micrographs of the porphyrin-passivated perovskite film prepared in this invention and the original film. All perovskite films, consisting of densely packed structures, exhibited a complete and uniform surface morphology. In the porphyrin-modified MAPbI3 film, the perovskite grain size was larger than that of the original film, indicating that the incorporation of porphyrin has a positive effect on both the surface morphology and grain size of the perovskite. This is because the amino and carboxyl functional groups in the porphyrin can coordinate and bond with defects in the perovskite, thereby reducing the nucleation barrier and Gibbs free energy during perovskite crystallization. Slowing the nucleation rate facilitates good perovskite orientation and grain size growth.

[0090] Figure 4The X-ray photoelectron spectra of Pb, I, and O elements of the porphyrin-passivated perovskite film prepared by the present invention and the original film are shown in FIG. Figure 4 As can be seen from (a), the original perovskite film has two main peaks at 138.5eV and 143.4eV, which are Pb 4f 7 / 2 and Pb 4f 5 / 2 The binding energy of Pb 4f in MAPbI3 films after porphyrin passivation modification shifts to a lower binding energy, which is attributed to the interaction between the porphyrin amino and carboxyl groups and the uncoordinated iodine anions and lead cations on the perovskite surface. The porphyrin amino groups are protonated by methylamine cations to generate –NH 3+ , accepting electrons from the uncoordinated iodine anion, causing the neighboring lead cations to produce an enhanced electron cloud density, resulting in a decrease in the binding energy of the lead element. The porphyrin carboxyl group can coordinate with the uncoordinated lead cations in the perovskite, resulting in an increase in the electron cloud density of the lead element and a decrease in the binding energy. The perovskite film MAPbI3 / POR3, which can simultaneously passivate both defects, exhibits the lowest binding energy, a result also Figure 4 The XPS spectrum of the I element (b) confirms that. Figure 4 The peaks of MAPbI3 / POR2 and MAPbI3 / POR3 in (c) and (d) are 529.2 eV and 529.5 eV, respectively, which are characteristic peaks of Pb–O bonds, providing sufficient evidence for the coordinated bonding between the uncoordinated lead cations in the perovskite and the porphyrin carboxyl groups.

[0091] Figure 5 The fluorescence spectra and time-resolved fluorescence spectra of the porphyrin-passivated perovskite film and the original film prepared by the present invention are shown in FIG. Figure 5 As shown in (a), the main emission peak of all perovskite films is located at 781nm. Compared with the original MAPbI3 film, the fluorescence intensity of MAPbI3 / POR1, MAPbI3 / POR2, and MAPbI3 / POR3 is significantly enhanced. This shows that the effective passivation of perovskite by porphyrin can significantly reduce the perovskite trap state density and inhibit non-radiative charge recombination losses. The luminescence intensity of the MAPbI3 / POR3 film is superior to that of other perovskite films, indicating that POR3 can effectively passivate the two types of defects in the perovskite through dual functions, contributing more photogenerated electrons and holes, thereby achieving higher fluorescence intensity. Figure 5 The long fluorescence lifetime of the MAPbI3 / POR3 film in (b) also confirms the above conclusion.

[0092] Figure 6The open-pore Z-scan curves of the porphyrin-passivated perovskite film prepared by the present invention and the original film under 1064nm and 532nm nanosecond laser excitation, respectively. The nonlinear absorption performance of the porphyrin-passivated perovskite film is significantly greater than that of the original perovskite film, indicating that the porphyrin molecules with amino and carboxyl functional groups can form bonding interactions with different types of positive and negative charge defects in the perovskite (i.e., uncoordinated iodine anions and uncoordinated lead cations), passivate the defects, enhance the free carrier absorption capacity and Pauli blocking effect of the perovskite material, and improve the nonlinear optical properties of the perovskite material. In addition, the carrier binding effect after porphyrin passivation and the efficient photoinduced charge / energy transfer between porphyrin and perovskite also contribute to the excellent nonlinear absorption mechanism. The optimal nonlinear optical absorption response of MAPbI3 / POR3 indicates the excellent dual-functional passivation characteristics of POR3. By fitting the Z-scan curves of the measured perovskite film samples, it was found that the nonlinear absorption coefficients of MAPbI3, POR1 / MAPbI3, POR2 / MAPbI3 and POR3 / MAPbI3 films at 1064 nm and 14 ns were 7.89×10 3 , 2.82×10 4 , 5.30×10 4 , 7.85×10 4 cm·GW -1 ; and the nonlinear absorption coefficients at 532 nm and 14 nanoseconds are -4.91×10 6 , -1.34×10 7 , -1.48×10 7 , -1.98×10 7 cm·GW -1 The above data show that under near-infrared nanosecond laser irradiation, the nonlinear absorption coefficient of the porphyrin-passivated perovskite film is 3.6 to 10 times that of the original perovskite film; under visible light nanosecond laser irradiation, the nonlinear absorption coefficient of the porphyrin-passivated perovskite film is 2.7 to 4 times that of the original perovskite film.

[0093] The above description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A porphyrin-passivated perovskite nanofilm material, characterized in that: It consists of a perovskite material and a porphyrin molecule for passivating the perovskite material, wherein the aniline groups and / or benzoic acid groups connected by acetylene groups at the meso positions on both sides of the porphyrin form bonds with uncoordinated halogen anions and / or uncoordinated metal cations in the perovskite. The general structural formula of the porphyrin molecule is as follows: Wherein, R1 and R2 are amino or carboxyl groups.

2. The porphyrin-passivated perovskite nanofilm material according to claim 1, characterized in that: The general formula of the perovskite material is ABX3, wherein A is a monovalent organic cation MA + , B is a divalent metal cation Pb 2+ , X is a halogen monovalent anion I ﹣ .

3. The porphyrin-passivated perovskite nanofilm material according to claim 1, characterized in that: The porphyrin molecule is 5,15-bis(2,6-dihexyloxyphenyl)-10,20-bis(4-aminophenylethynyl)porphyrin, 5,15-bis(2,6-dihexyloxyphenyl)-10,20-bis(4-carboxylphenylethynyl)porphyrin or 5,15-bis(2,6-dihexyloxyphenyl)-10-(4-aminophenylethynyl)-20-(4-carboxylphenylethynyl)porphyrin.

4. The method for preparing a porphyrin-passivated perovskite nanofilm material according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: Preparation of perovskite precursor solution containing PbI2 and MAI; S2: preparing an antisolvent containing porphyrin molecules; S3: spin-coating the perovskite precursor solution and the anti-solvent containing porphyrin molecules on a substrate to form a film, and then annealing to obtain a target material.

5. The method for preparing a porphyrin-passivated perovskite nano-film material according to claim 4, wherein: In step S1, the mass ratio of PbI2 and MAI in the perovskite precursor solution is (2-4):

1.

6. The method for preparing a porphyrin-passivated perovskite nano-film material according to claim 4, wherein: In step S1, the solvent used in the perovskite precursor solution is a mixture of ultra-dry DMF and ultra-dry DMSO; The mass ratio of the ultra-dry DMF to the ultra-dry DMSO is (4-10):

1.

7. The method for preparing a porphyrin-passivated perovskite nano-film material according to claim 4, wherein: In step S2, the antisolvent is chloroform, and the concentration of porphyrin molecules added is 0.2-0.5 mg mL -1 .

8. The method for preparing a porphyrin-passivated perovskite nano-film material according to claim 4, wherein: In step S3, the spin coating process is as follows: dropping the perovskite precursor solution onto the substrate, spin coating at a low speed to form a film, and then adding an anti-solvent containing porphyrin during high-speed spin coating until a bright film is formed. The substrate includes a quartz sheet, a common glass sheet, an ITO sheet or a FTO sheet.

9. The method for preparing a porphyrin-passivated perovskite nano-film material according to claim 4, wherein: In step S3, the annealing temperature is 85-100° C. and the time is 10-15 minutes.

10. Use of the porphyrin-passivated perovskite nanofilm material according to any one of claims 1 to 3 in the field of nonlinear optical material technology.

Images