Excited state charge delocalization or localization of fullerene-aniline derivatives and design methods

Abstract

The present application aims to provide a fullerene-aniline derivative with excited state hole delocalization or localization, which has a structure shown in formula (I), wherein each group is defined as described in the specification, and has excited state hole localization characteristics or excited state hole delocalization characteristics, and can form a fast charge separation or a long-lived charge separation state system.

Description

Technical Field

[0001] This invention relates to the design and application of optoelectronic functional materials, and in particular to fullerene-aniline derivatives with charge delocalization or localization characteristics, their design, preparation methods, and analytical methods for excited-state charge transfer dynamics. Background Technology

[0002] High-efficiency, long-life, and low-cost optoelectronic functional materials are a future research hotspot, playing an important role in energy conversion, storage, and utilization. They can be applied to fields such as solar cells, photoluminescence, molecular sensing, photocatalysis, and artificial photosynthesis, and are expected to make significant contributions to achieving sustainable development and realizing the "dual carbon target".

[0003] Donor-acceptor structures with energy level gradients readily undergo charge transfer or charge separation upon photoexcitation, a crucial process for the effective functioning of optoelectronic materials. Effective charge separation, including ultrafast charge separation and long-lived charge-separated states, is key to determining energy conversion efficiency. Common effective charge separation design strategies include introducing heavy atoms to increase the charge separation rate, designing orthogonal structures to reduce orbital overlap, and growing donor-acceptor bridging structures to reduce electronic coupling. However, these strategies are challenging in molecular design and fabrication, making the simple design of model molecules very difficult. Studies have shown that the characteristics of charge delocalization or localization in excited states significantly affect the generation process of free carriers, charge separation and recombination processes, and the lifetime of excited states. Charge delocalization structures facilitate ultrafast charge separation, increasing the yield of free carriers and thus improving the energy conversion efficiency of optoelectronic devices. Charge localization structures help form long-lived charge-separated states, promoting charge transport and subsequent redox reactions.

[0004] Regioisomers based on substituted benzene possess unique properties, including differences in conjugated electronic effects between para and meta substitutions, and differences in geometric effects between ortho and para substitutions. Furthermore, benzene-substituted regioisomers are simple to prepare, highly scalable, and hold promise for designing model molecules with broader application value. Aniline derivatives, represented by triphenylamine, are excellent donor materials, commonly used as sensitizer precursors in dye-sensitized solar cells, modifying groups in photoluminescent materials, and in the design of photocatalytic or artificial photosynthetic reaction centers. Leveraging the regioisomerism of the benzene ring in the aniline structure, donor units with different electronic effects can be designed, potentially leading to materials with delocalized or localized excited-state holes.

[0005] With C 60Fullerenes, represented by [specific species name], have been extensively studied in energy, chemical engineering, biomedicine, and molecular devices due to their unique structure and special properties since their discovery in 1985. In particular, fullerenes possess high electron affinity and low recombination energy, readily exhibiting ultrafast charge separation and slow charge recombination, making them frequently used as electron acceptor materials in optoelectronics. Furthermore, the carbon-carbon double bonds in the fullerene carbon cage readily undergo various addition reactions, making it possible to chemically modify donor molecules outside the carbon cage, thus facilitating the construction of novel fullerene acceptor-donor structures. Therefore, selecting fullerenes as electron acceptors to design high-efficiency optoelectronic materials to improve energy conversion efficiency, enabling their more convenient application in energy, chemical engineering, and other fields, and better alleviating the energy crisis, is of significant scientific importance for achieving sustainable development and the "dual carbon" goal. Summary of the Invention

[0006] The purpose of this invention is to provide fullerene-aniline derivatives with excited-state hole delocalization or localization characteristics, which have excited-state hole localization or excited-state hole delocalization characteristics, and have a long charge-separated state lifetime or a rapid charge separation process.

[0007] In one aspect of the present invention, a fullerene-aniline derivative having excited-state hole delocalization or localization is provided, the fullerene-aniline derivative having the structure shown in formula (I);

[0008]

[0009] In the formula,

[0010] Full represents fullerene; Ph represents benzene ring;

[0011] L1 and L2 are each independently selected from single bond, alkynyl, -Ph-, -alkynyl-Ph-alkynyl, -alkynyl-Ph-, or -Ph-alkynyl;

[0012] R1 and R2 are each independently selected from the structure shown in equation (II):

[0013]

[0014] in,

[0015] R4 and R5 are each independently selected from H, D, alkyl, alkoxy, alkynyl, and NR. a R b Or aryl, wherein the aryl group is optionally substituted with a substituent selected from alkenyl or ynyl;

[0016] R3 is selected from alkyl groups;

[0017] R a R b Each is independently selected from C1-C6 alkyl groups.

[0018] In some specific embodiments, R3 is selected from C1-C6 alkyl groups;

[0019] Preferably, R3 is selected from methyl, ethyl, or hexyl.

[0020] Preferably, R3 is ethyl.

[0021] Preferably, L1 and L2 are each independently selected from single bond, C2-C6 ynyl group, -Ph-, (-C2-C6 ynyl)-Ph-(C2-C6 ynyl), -(C2-C6 ynyl)-Ph- or -Ph-(C2-C6 ynyl).

[0022] Preferably, L1 and L2 are each independently selected from single bond, C2-C4 ynyl group, -Ph-, (-C2-C4 ynyl)-Ph-(C2-C4 ynyl), -(C2-C4 ynyl)-Ph- or -Ph-(C2-C4 ynyl).

[0023] Preferably, L1 and L2 are each independently selected from single bonds, C1-C6 alkynyl groups, or -Ph-.

[0024] In some specific implementation methods, R4 and R5 are each independently selected from H, D, C1-C6 alkyl, C1-C6 alkoxy, C2-C6 alkynyl, NR a R b Or 5 to 8 aryl groups, wherein the 5 to 8 aryl groups are optionally substituted with substituents selected from C2-C4 alkenyl or C2-C4 alkynyl.

[0025] Preferably, R4 and R5 are each independently selected from H, D, C1-C6 alkyl, C1-C6 alkoxy, and NR. a R b Or C2-C4 alkynyl-substituted 5 to 8 aryl groups.

[0026] Preferably, R4 and R5 are each independently selected from H or C1-C6 alkoxy groups.

[0027] Preferably, R4 and R5 are each independently selected from H or methoxy.

[0028] Preferably, the compound of formula (II) has the structure shown in formula (IIa), formula (IIb) or formula (IIc):

[0029]

[0030] In the formula, R4 and R5 are defined as before.

[0031] In some specific embodiments, the compound of formula (I) has the structure shown in formula (Ia), formula (Ib), formula (Ic), formula (Id), formula (Ie), or formula (If):

[0032]

[0033] Preferably, the compound of formula (I) has the structure shown in formula (Ia), formula (Ib), or formula (Ic):

[0034]

[0035] Preferably, the compound of formula (I) has the structure shown in formula (III), formula (IV), formula (V), formula (VI) or formula (VII):

[0036]

[0037] Among them, R4, R5, R4', and R5' are the same as before.

[0038] Preferably, the fullerene-aniline derivative is an excited-state hole-delocalized fullerene-aniline derivative, and the fullerene-aniline derivative has the structure shown in formula (III):

[0039]

[0040] In some specific embodiments, the fullerene-aniline derivative is a fullerene-aniline derivative with excited-state hole localization, and the bond connecting the phenyl group to the -L1-R1 structure and the -L2-R2 structure is located at the meta position of the bond connecting the phenyl group to the tertiary amino group.

[0041] In the -L1-R1 and -L2-R2 structures, the bond connecting the phenyl group to the phenyl group is located at the ortho position of the bond connecting the phenyl group to the tertiary amino group, provided that the -L1-R1 and -L2-R2 structures have significant steric hindrance.

[0042] In some specific embodiments, the excited-state hole-localized fullerene-aniline derivative has the structure shown in formula (IV), (V), (VI), or (VII):

[0043]

[0044] In some specific embodiments, the fullerene-aniline derivative is selected from the following formula:

[0045]

[0046]

[0047] in,

[0048] Full represents fullerene; R3 is defined as before.

[0049] Preferably, the fullerene is C2n (n≥10,n≠11).

[0050] Preferably, the fullerene is C 60 .

[0051] Preferably, the fullerene-aniline derivative is selected from the following compounds:

[0052]

[0053]

[0054] In another aspect, the present invention provides a method for preparing the above-mentioned aniline-fullerene derivative, which includes the following steps: reacting a fullerene with an aniline compound of formula (III) under certain conditions to obtain the derivative.

[0055]

[0056] In the formula,

[0057] Ph, L1, L2, R1, and R2 are as described above.

[0058] R6 is selected from -CHO or,

[0059] Preferably, the addition reaction is selected from either the 1,3-dipolar cycloaddition reaction or the Bingle reaction.

[0060] In one embodiment, in the aniline compound represented by formula (III), R6 is... The addition reaction is a Binger reaction, and the preparation method includes the following steps: fullerene is reacted with compound of formula (III) in the presence of carbon tetrabromide and a base to obtain the product.

[0061] Preferably, the alkali is either DBU or NaH.

[0062] Preferably, in the preparation method, the molar ratio of the fullerene to the aniline compound shown in formula (III) is 1.2-1.5:1.

[0063] In one embodiment, R6 in the aniline compound represented by formula (III) is CHO, the addition reaction is a 1,3-dipolar cycloaddition reaction, and the preparation method includes the following steps: adding fullerene to the compound of formula (III) in the presence of an amino acid to obtain the compound.

[0064] Preferably, the amino acid is selected from either ethylglycine or methylglycine.

[0065] In one specific embodiment, the amino acid is N-ethylglycine.

[0066] Preferably, in the preparation method, the molar ratio of the fullerene to the aniline compound shown in formula (III) is 1.1-1.8:1, for example, it can be 1.1-1.5:1, more preferably 1.5:1.

[0067] In another aspect, the present invention provides an intermediate for preparing the above-mentioned fullerene-aniline derivative, wherein the intermediate has the structure shown in formula (IIIa):

[0068]

[0069] Preferably, the compound of formula (IIIa) has the structure shown in formula (IIIaa), formula (IIIab), formula (IIIac), formula (IIIad), formula (IIIae), or formula (IIIaf):

[0070]

[0071] Preferably, the compound of formula (IIIa) has the structure shown in formula (IIIaa), formula (IIIab), or formula (IIIac):

[0072]

[0073] Preferably, the compound of formula (III) has the structure shown in formula (IIIb), (IIIc), (IIId), (IIIe), or (IIIf):

[0074]

[0075]

[0076] R4, R5, R4', and R5' are each defined as before.

[0077] Preferably, the intermediate is selected from the following compounds:

[0078]

[0079]

[0080] In another aspect, the present invention provides a method for obtaining an excited-state hole delocalization or localization structure, which is obtained by reacting a fullerene with an aniline compound of formula (III) in the presence of an amino acid.

[0081] Preferably, the addition reaction includes any one of the following: 1,3-dipolar cycloaddition reaction and Binger reaction.

[0082] Preferably, in the aniline compound represented by formula (III), R3 is CHO. The addition reaction is a 1,3-dipolar cycloaddition reaction, and the preparation method includes the following steps: reacting a fullerene with a compound of formula (III) in the presence of an amino acid to obtain the compound.

[0083] In another aspect, the present invention provides a method for testing the excited-state charge distribution and excited-state lifetime of a fullerene-aniline derivative, comprising:

[0084] (1) Excitation of fullerene-aniline derivatives using near-ultraviolet-visible light source;

[0085] (2) The femtosecond transient absorption spectrum of the above molecules is measured, and the distribution of holes during the excited state charge separation process is determined by combining the spectral evolution.

[0086] (3) The dynamic time constant is obtained by global fitting analysis.

[0087] The kinetic time constants include the kinetic time constants for charge transfer, charge separation, and charge recombination processes.

[0088] In one embodiment, the femtosecond transient absorption spectrum is measured using a femtosecond transient absorber.

[0089] Preferably, the near-ultraviolet-visible light source in step (1) is a light source with an emission wavelength of 266nm-532nm.

[0090] Preferably, the near-ultraviolet-visible light source in step (1) is a light source with an emission wavelength of 350 nm.

[0091] In another aspect, the present invention provides the application of the above-mentioned fullerene-aniline derivative, the fullerene-aniline derivative prepared by the above method, and the above-mentioned intermediate in the preparation of optoelectronic materials.

[0092] Preferably, its application in the preparation of optoelectronic materials for photoelectric conversion, photoluminescence, molecular sensing, and photocatalytic organic reactions.

[0093] Preferably, its application in the preparation of solar cells or photocatalytic materials.

[0094] The beneficial effects of this invention:

[0095] The inventor of this invention previously reported on C 60 -DDPA derivatives were found to have a charge-separated state lifetime of less than 10 ps in toluene (Phys. Chem. Chem. Phys. 2019, 21, 24291-24295), and their properties differed significantly from those of the molecule described in this invention. Furthermore, after analysis of C... 60 -MCB and C 60-TPA The excited states of the derivatives were studied, and it was found that both molecules relax to a stable C10 state in toluene solution. 60 Triple states and charge-separated states have short lifetimes or cannot be formed.

[0096] This invention discloses a method for designing donor-acceptor structures with excited-state charge delocalization or localization based on fullerene-aniline derivatives, and the influence of delocalization and localization on the lifetime of the charge-separated state. The aniline structure in this invention is obtained through catalytic coupling, and the fullerene-aniline derivative is obtained by modifying the aniline structure onto the surface of a carbon cage via an addition reaction. By changing the substitution method of the aniline structure, significantly different excited-state localized or delocalized charge-separated systems can be obtained. Transient absorption can be used to characterize the photophysical process of excited-state relaxation of fullerene-aniline derivatives. Combined with data fitting and spectral analysis, information on excited-state delocalization or localization and the kinetic mechanism can be obtained. The fullerene-aniline derivatives provided by this invention have novel structures, simple design, easily tunable excited-state lifetimes and charge-separation rates, and can obtain significantly different delocalized or localized systems. They can be used to guide the design of optoelectronic functional materials such as organic solar cells, proposing a new strategy for designing charge-delocalized or localized systems, and solving the problems of difficult design and complex preparation of previous intermolecular charge-delocalized systems. Attached Figure Description

[0097] Figure 1 This is the femtosecond transient absorption spectrum of the fullerene-aniline derivative 1 with excited-state hole delocalization in Example 7.

[0098] Figure 2 The figures are the excited-state species kinetic curves and their respective time constants obtained by global fitting of the excited-state hole-delocalized fullerene-aniline derivative 1 in Example 7.

[0099] Figure 3 This is the femtosecond transient absorption spectrum of the fullerene-aniline derivative 2 with excited-state hole localization in Example 7.

[0100] Figure 4 The figures are the excited-state species dynamic curves and their respective time constants obtained by global fitting of the excited-state hole-localized fullerene-aniline derivative 2 in Example 7.

[0101] Figure 5 This is the femtosecond transient absorption spectrum of the fullerene-aniline derivative 3 with excited-state hole localization in Example 7.

[0102] Figure 6 The figures are the excited-state species dynamic curves and their respective time constants obtained by global fitting of the excited-state hole-localized fullerene-aniline derivative 3 in Example 7. Detailed Implementation

[0103] I. Definition

[0104] The term "alkyl" refers to a saturated aliphatic hydrocarbon group, including straight-chain or branched saturated hydrocarbon groups having the indicated number of carbon atoms. For example, the term "C1-C6 alkyl" includes C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, and C6 alkyl, examples of which include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, 2-pentyl, 3-pentyl, n-hexyl, 2-hexyl, 3-hexyl, etc.

[0105] As used herein, the term "fullerene" is a series of spherical cluster molecules composed of an even number of carbon atoms, consisting of 12 five-membered rings and the rest six-membered rings; it is a cage-like structure composed of carbon atoms. Fullerenes include hollow fullerenes and metallofullerenes, wherein the hollow fullerene is a cage-like structure composed of a single carbon atom.

[0106] As used herein, the term "metal fullerene" refers to a class of compounds with special structures and properties formed by incorporating various atoms, ions, or atomic clusters within the carbon cage structure of fullerenes. These compounds are commonly referred to as endohedral fullerenes, generally denoted by M@C. 2n The form is represented as M, where M represents a metallic element.

[0107] The term “DBU” refers to 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0108] II. Examples

[0109] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0110] Example 1: Preparation of aniline compound lc

[0111]

[0112] (1) Mix 0.76 mmol (i.e. 396.7 mg) of 4-[bis-(4-iodophenyl)amino]benzaldehyde of formula (1a) and 3.14 mmol (i.e. 906.5 mg) of 4-(diphenylamino)phenylboronic acid of formula (1b), dissolve in 60 mL of 1,2-dimethoxyethane, add 4 mL of 1 mol / L sodium hydroxide aqueous solution, heat and stir at 100 °C under argon atmosphere, and reflux for 2-4 hours;

[0113] (2) After the reaction is complete, cool to room temperature, add saturated brine, extract the mixture with ethyl acetate, dry the extracted product with anhydrous sodium sulfate, evaporate the solvent, and then purify it with silica gel column to obtain the product of formula (1c).

[0114] (3) The proton NMR spectrum of the product of formula (1c) is as follows: 1 H NMR (400MHz, CDCl3-d, 298K) = δ: 7.04 (4H, t), 7.12-7.15 (12H, m), 7.23-7.29 (14H, m), 7.47 (4H, d), 7.55 (4H, d), 7.72 (2H, d), 9.83 (1H, s).

[0115] Example 2: Preparation of aniline compound 2c

[0116]

[0117] (1) Mix 0.57 mmol (i.e. 298.5 mg) of 4-[bis-(4-iodophenyl)amino]benzaldehyde of formula (1a) and 2.26 mmol (i.e. 653.2 mg) of 3-(N,N-diphenylamino)phenylboronic acid of formula (2b), dissolve in 50 mL of 1,2-dimethoxyethane, add 3 mL of 1 mol / L sodium hydroxide aqueous solution, heat and stir at 100 °C under argon atmosphere, and reflux for 2-4 hours;

[0118] (2) After the reaction is complete, cool to room temperature, add saturated brine, extract the mixture with ethyl acetate, dry the extracted product with anhydrous sodium sulfate, evaporate the solvent, and then purify it with silica gel column to obtain the product of formula (2c).

[0119] (3) The proton NMR spectrum of the product of formula (2c) is as follows: 1 H NMR (400MHz, CDCl3-d, 298K) = δ: 7.00-7.06 (6H, m), 7.07-7.09 (2H, d), 7.12-7.14 (8H, m), 7.16-7.18 (4H, d) ), 7.20-7.22(2H,d),7.24-7.28(10H,m),7.31(2H,d),7.44-7.46(4H,d),7.68-7.70(2H,d),9.82(1H,s).

[0120] Example 3: Preparation of aniline compound 3c

[0121]

[0122] The specific steps include:

[0123] (1) Mix 0.37 mmol (i.e. 194.2 mg) of 4-[bis-(4-iodophenyl)amino]benzaldehyde of formula (1a) and 1.38 mmol (i.e. 398.4 mg) of 2-(N,N-diphenylamino)phenylboronic acid of formula (3b), dissolve in 60 mL of 1,2-dimethoxyethane, add 3 mL of 1 mol / L sodium hydroxide aqueous solution, heat and stir at 100 °C under argon atmosphere, and reflux for 2-4 hours;

[0124] (2) After the reaction is complete, cool to room temperature, add saturated brine, extract the mixture with ethyl acetate, dry the extracted product with anhydrous sodium sulfate, evaporate the solvent, and then purify it with silica gel column to obtain the product of formula (3c).

[0125] (3) The 1H NMR spectrum of the product of formula (3c) is as follows: 1 H NMR (400MHz, CDCl3-d, 298K) δ: 6.76-6.83 (8H, m), 6.86-6.89 (8H, d), 7.05-7.09 (8H, t), 7.13-7.1 6(4H,d),7.15-7.19(2H,t),7.22-7.30(4H,m),7.32-7.37(4H,t),7.61-7.64(2H,d),9.79(1H,s).

[0126] Example 4: Preparation of Fullerene-Aniline Derivative 1

[0127]

[0128] (1) 0.063 mmol (47.9 mg) of aniline compound 1 and 0.092 mmol (66.1 mg) of C 60 Dissolve in 40 mL toluene, then add 0.057 mmol (5.9 mg) of N-ethylglycine, purge with argon as a protective gas, heat to 120 °C under reflux and stir to carry out cycloaddition reaction for 3-6 hours;

[0129] (2) After the reactants were cooled for half an hour, the solution was evaporated to dryness, the product was dissolved in toluene, and the remaining solid impurities were removed by filtration. Then, high performance liquid chromatography was used for separation and purification. The separation and purification steps were as follows: Buckyprep column (20×250mm, Cosmosil) was used for separation. Toluene was used as the mobile phase, the flow rate of toluene was 6mL / min, the sample concentration was 1mg / mL, and 6mL was injected each time. The UV monitoring wavelength was 310nm. The peak time of fullerene-aniline derivative 1 on the Buckyprep column was 15min. The product was detected by MALDI-TOF mass spectrometry to obtain fullerene-aniline derivative 1.

[0130] 1 H NMR (400MHz, CDCl3-d, 298K)δ:0.88(3H,m),1.32(2H,m),3.53(1H,s),4.23(1H,s),5.16(1H,s), 7.00-7.04(4H,t),7.08-7.12(16H,m),7.18-7.20(2H,d),7.24-7.27(10H,m),7.42-7.44(8H,d)

[0131] Example 5: Preparation of Fullerene-Aniline Derivative 2

[0132]

[0133] (1) 0.187 mmol (142.2 mg) of aniline compound 2 was reacted with 0.267 mmol (191.9 mg) of C 60 Dissolve in 100 mL toluene, then add 0.168 mmol (17.3 mg) of N-ethylglycine, purge with argon as a protective gas, heat to 120 °C under reflux and stir to carry out cycloaddition reaction for 3-6 hours;

[0134] (2) After the reactants were cooled for half an hour, the solution was evaporated to dryness, the product was dissolved in toluene, and the remaining solid impurities were removed by filtration. Then, high performance liquid chromatography was used for separation and purification. The separation and purification steps were as follows: Buckyprep column (20×250mm, Cosmosil) was used for separation. Toluene was used as the mobile phase, the flow rate of toluene was 6mL / min, the sample concentration was 1mg / mL, and 6mL was injected each time. The UV monitoring wavelength was 310nm. The peak time of the fullerene-aniline derivative 2 product on the Buckyprep column was 15min. The product was detected by MALDI-TOF mass spectrometry. The main component obtained was fullerene-aniline derivative 2.

[0135] 1 H NMR (400MHz, CDCl3-d, 298K)δ:0.86-0.92(3H,m),1.31(2H,m),3.46(1H,s),4.22(1H,s),5.08(1H, s),6.98-7.03(8H,m),7.10-7.12(12H,d),7.17-7.19(2H,d),7.22-7.28(14H,m),7.32-7.34(4H,d)

[0136] Example 6: Preparation of Fullerene-Aniline Derivative 3

[0137]

[0138] (1) 0.058 mmol (44.1 mg) of aniline compound 3 was reacted with 0.1 mmol (72 mg) of C 60 Dissolve in 50 mL toluene, then add 0.051 mmol (5.2 mg) of N-ethylglycine, purge with argon as a protective gas, heat to 120 °C under reflux and stir to carry out cycloaddition reaction for 3-6 hours;

[0139] (2) After the reactants were cooled for half an hour, the solution was evaporated to dryness, the product was dissolved in toluene, and the remaining solid impurities were removed by filtration. Then, high performance liquid chromatography was used for separation and purification. The separation and purification steps were as follows: Buckyprep column (20×250mm, Cosmosil) was used for separation. Toluene was used as the mobile phase, the flow rate of toluene was 6mL / min, the sample concentration was 1mg / mL, and 6mL was injected each time. The UV monitoring wavelength was 310nm. The peak time of the fullerene-aniline derivative 3 product on the Buckyprep column was 16min. The product was detected by MALDI-TOF mass spectrometry. The main component obtained was fullerene-aniline derivative 3.

[0140] 1 H NMR (400MHz, CDCl3-d, 298K)δ:0.86-0.90(3H,m),1.31(2H,m),3.60(1H,s),4.38(1H,s),5.34(1H, s),6.64-6.66(4H,d),6.76-6.80(6H,t),6.83-6.88(12H,m),7.03-7.07(12H,t),7.29-7.35(6H,m)

[0141] Example 7: Detection of excited-state charge distribution and kinetic properties and lifetime analysis of fullerene-aniline derivatives

[0142] The apparatus used in the experiment consisted of a pump-probe spectrometer and an ultrafast laser amplification system.

[0143] The pump light has a center wavelength of 350 nm and a pulse power of approximately 100-500 microwatts. It is emitted through an optical parametric amplifier (TOPAS-800-fs) (excited by a Ti:sapphire regenerative amplifier with a center wavelength of 800 nm, a pulse duration of approximately 25 fs, and a pulse energy of approximately 3 millijoules). The seed light is a mode-locked Ti:sapphire laser system (Micra 5, Coherent), and the pump light uses a 1 kHz Nd:YLF laser (Evolution 30, Coherent). A relatively weak probe light pulse (less than 0.5 microjoules per sample) is generated through a continuous, stable white light (WLC) beam (generated by rotating an 800 nm beam and focusing it onto a 4.55 mm thick CaF2 crystal) at 400-700 nm. Both the pump and probe lights are linearly polarized. The pump-probe spectrometer has a response of approximately 80 fs, achieved through cross-correlated pump and probe pulses. The pump light and probe light have precise spatial overlap, with diameters of 800 μm and 300 μm, respectively. At the center is a 1.2 mm thick sample cell, and the optimal transient absorption signal is obtained through a laser analyzer (BG-USB-SP620, Ophir-Spiricon).

[0144] The changes in the pump and probe pulse delays are achieved by altering the optical delay line (minimum 1.56 fs, maximum delay 3.2 ns). Mechanical modulation at 500 Hz is used to manipulate the pump pulse, for example, to ensure that transient absorption spectra can be alternately recorded with different pulses. The probe light is first split into two very small parts, occurring simultaneously at the chopper and monitor. The stability of the probe light is controlled by two independent photodiode detectors. It is then separated into two parts: 70% is concentrated in the sample cell, overlapping with the pump light to generate a probe signal, while the remaining 30% is directed to the sample cell via a different path to ensure a good signal-to-noise ratio.

[0145] The transient pump spectrum absorption map can be visualized directly using 1024-pixel imaging, and then further processed using ExiPro 2.6 software.

[0146] Testing steps:

[0147] (1) Select 0.5-2 mL of solutions with a concentration of 10- 6 mol / L-10- 5 A solution of o-dichlorobenzene of fullerene-aniline derivatives 1, 2 and 3 in mol / L (maximum absorbance in a 1 mm optical path cuvette is about 0.2-0.8 OD) was placed in a 1 mm optical path cuvette equipped with a rotor and mounted on a rotating stage with a rotation speed of 2000 rpm to prevent local light damage to the sample.

[0148] (2) Excitation was performed using 350nm near-ultraviolet light, and transient absorption spectra in the visible-near-infrared region (wavelength range 500nm-1300nm) were detected.

[0149] (3) Assign the distribution of holes during excited-state charge separation based on the spectral evolution at different times (see...). Figure 1 , Figure 3 , Figure 5 );

[0150] (4) Based on the global fitting, select single-wavelength data from the curves of different wavelengths changing with time to create a dynamic curve of the change with time (see...). Figure 2 , Figure 4 , Figure 6 ).

[0151] Since the spectra and dynamics of multiple excited-state species are mixed when a molecule is excited, a global fitting method is used with a continuous model to obtain the main excited-state components and the time constants of the evolution between the corresponding excited-state species, i.e., lifetimes. The criterion for determining charge-separated states is: the presence of excited-state absorption peaks of positive and negative ions (radical ion pairs) on the same time scale; the corresponding time constant is the lifetime of the charge-separated state.

[0152] 7.1: Detection and lifetime analysis of excited-state charge distribution and kinetic properties of excited-state delocalized fullerene-aniline derivative 1

[0153] Analysis of excited-state charge distribution:

[0154] Depend on Figure 1 It can be seen that when a molecule is excited by 350nm pump light, electrons transition to an excited state, then rapidly relax, resulting in charge separation. C appears at 1020nm and 510nm, respectively. 60 The excited-state absorption signals of anionic free radicals and aniline derivative cationic free radicals are observed, and a broad absorption peak belonging to the delocalized hole distribution appears in the near-infrared region of 1000nm-1300nm.

[0155] Excited-state lifetime analysis:

[0156] Depend on Figure 2 It can be seen that when a molecule is excited by a 350nm pump light, the electron transitions from the ground state to the excited state. Through global fitting analysis and using a continuous model, it can be obtained that the evolution of the excited state goes through three main processes: local excited state, charge transfer state, and charge separation state. The three time constants obtained are 0.9ps, 2.5ps, and 102ps, which are the time constants from the local excited state to the charge transfer state, the time constants from the charge transfer state to the charge separation state (i.e., the charge separation time constant), and the time constants from the charge separation state back to the ground state (i.e., the charge separation lifetime), respectively.

[0157] 7.2: Detection and lifetime analysis of excited-state charge distribution and kinetic properties of fullerene-aniline derivative 2 with excited-state charge localization.

[0158] Analysis of excited-state charge distribution:

[0159] Depend on Figure 3 It can be seen that when a molecule is excited by a 350nm pump light, electrons transition to an excited state, then rapidly relax, resulting in charge separation. C appears at 1020nm and 770nm, respectively. 60 The excited-state absorption signals of anionic radicals and localized triphenylamine cation radicals do not show broad absorption peaks in the near-infrared region, which are attributed to localized hole distribution, indicating that the excited-state holes of fullerene-aniline derivative 2 are localized.

[0160] Excited-state lifetime analysis:

[0161] Depend on Figure 4 It can be seen that when the molecule is excited by a 350 nm pump light, electrons transition from the ground state to the excited state. Through global fitting analysis, using the same continuous model, it can be obtained that the evolution of the excited state goes through three main processes: a locally excited state, a charge-transfer state, and a charge-separation state. The three time constants obtained are 2.5 ps, 55.2 ps, and 2300 ps, ​​which are the time constants from the locally excited state to the charge-transfer state, from the charge-transfer state to the charge-separation state (i.e., the charge-separation time constant), and from the charge-separation state back to the ground state (i.e., the charge-separation lifetime), respectively. The results show that the hole-localized fullerene-aniline derivatives of the excited state have a longer charge-separation lifetime, but also a slower charge-separation process.

[0162] 7.3: Detection and lifetime analysis of excited-state charge distribution and kinetic properties of excited-state charge-localized fullerene-aniline derivative 3

[0163] Analysis of excited-state charge distribution:

[0164] Depend on Figure 5 It can be seen that when a molecule is excited by a 350nm pump light, electrons transition to an excited state, then rapidly relax, resulting in charge separation. C appears at 1020nm and 770nm, respectively. 60 The excited-state absorption signals of anionic radicals and localized triphenylamine cation radicals do not show broad absorption peaks in the near-infrared region, which are attributed to localized hole distribution, indicating that the excited-state holes of fullerene-aniline derivative 3 are localized.

[0165] Excited-state lifetime analysis:

[0166] Depend on Figure 6It can be seen that when the molecule is excited by a 350 nm pump light, electrons transition from the ground state to the excited state. Through global fitting analysis, using the same continuous model, it can be obtained that the evolution of the excited state goes through three main processes: local excited state, charge transfer state, and charge separation state. The three time constants obtained are 1.8 ps, 30.2 ps, and 1000 ps, ​​which are the time constants from the local excited state to the charge transfer state (i.e., the charge separation time constant), from the charge transfer state to the charge separation state, and from the charge separation state back to the ground state (i.e., the charge separation state lifetime), respectively. This indicates that the fullerene-aniline derivative with excited-state hole localization has a longer charge separation state lifetime, but also a slower charge separation process. It also shows that the results for fullerene-aniline derivative 3 are similar to those for fullerene-aniline derivative 2.

[0167] Table 1 summarizes the time constants and lifetimes of the excited-state charge separation process for fullerene aniline derivatives 1, 2, and 3.

[0168] Table 1: Charge separation time constant and charge separation state lifetime

[0169] molecular Charge separation time constant Charge-separated state lifetime Equation (1) 2.5ps 102ps Equation (2) 55.2ps 2300ps Equation (3) 30.2ps 1000ps

[0170] Therefore, by modifying aniline regiomeric derivatives with fullerene carbon cages, the delocalization or localization of excited-state charge distribution was controlled, further enabling the regulation of charge separation and recombination dynamics. This invention reveals that meta-substituted regiomeric derivatives with disrupted electron conjugation and ortho-substituted regiomeric derivatives with large steric hindrance exhibit hole localization in the excited state; while para-substituted regiomeric derivatives exhibit hole delocalization in the excited state. This invention provides a new approach for designing charge-delocalized or charge-localized optoelectronic materials, offers important reference for a deeper understanding of the impact of charge delocalization or localization on excited-state photophysical processes, and is of great significance for the more efficient development of optoelectronic materials.

[0171] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A fullerene-aniline derivative in which excited-state holes are delocalized or localized, wherein, The fullerene-aniline derivative has the structure shown in formula (I); （I） In the formula, Indicates fullerene; L1 and L2 are each independently selected from single bonds, alkynyl groups, and -Ph-; R1 and R2 are each independently selected from the structure shown in equation (II): (II) in, R4 and R5 are each independently selected from H, D, C1-C6 alkyl, and C1-C6 alkoxy groups; R3 is selected from C1-C6 alkyl groups; It is a benzene ring.

2. The fullerene-aniline derivative according to claim 1, wherein, R3 is selected from methyl, ethyl, and hexyl.

3. The fullerene-aniline derivative according to claim 1, wherein, R3 is an ethyl group.

4. The fullerene-aniline derivative according to claim 1, wherein, L1 and L2 are each independently selected from single bonds, C2-C6 alkynyl groups, and -Ph-.

5. The fullerene-aniline derivative according to claim 1, wherein, L1 and L2 are each independently selected from single bonds, C2-C4 alkynyl groups, and -Ph-.

6. The fullerene-aniline derivative according to claim 1, wherein, L1 and L2 are each independently selected from single bonds and -Ph-.

7. The fullerene-aniline derivative according to claim 1, wherein, R4 and R5 are each independently selected from H or C1-C6 alkoxy groups.

8. The fullerene-aniline derivative according to claim 1, wherein, R4 and R5 are each independently selected from H or methoxy groups.

9. The fullerene-aniline derivative according to claim 1, wherein, The compound of formula (II) has the structure shown in formula (IIa), formula (IIb) or formula (IIc): (IIa) (IIb) (IIc) In the formula, R4 and R5 are defined as before.

10. The fullerene-aniline derivative according to claim 1, wherein, The compound of formula (I) has the structure shown in formula (Ia), formula (Ib), formula (Ic), formula (Id), formula (Ie), or formula (If): (Ia) (Ib) (Ic) (Id) (Ie) (If); In the formula, Full, R3, R1, L1, R2, and L2 are each defined as described in claim 1.

11. The fullerene-aniline derivative according to claim 1, wherein, The compound of formula (I) has the structure shown in formula (Ia), formula (Ib) or formula (Ic): (Ia) (Ib) (Ic); In the formula, Full, R3, R1, L1, R2, and L2 are each defined as described in claim 1.

12. The fullerene-aniline derivative according to any one of claims 1-11, wherein the fullerene-aniline derivative is selected from the following formula: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 ； in, Full represents fullerene; R3 is defined as described in any one of claims 1-11.

13. The fullerene-aniline derivative according to claim 12, wherein, The fullerene is C 2n n≥10 and n≠11.

14. The fullerene-aniline derivative according to claim 13, wherein, The fullerene is C 60 .

15. The fullerene-aniline derivative according to claim 1, wherein, The fullerene-aniline derivative is selected from the following compounds: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 。 16. A method for preparing an aniline-fullerene derivative according to any one of claims 1-15, comprising the following steps: The fullerene is obtained by addition reaction with aniline compounds of formula (IIIab), (IIIac), (IIIad), (IIIae), or (IIIaf) in the presence of ethylglycine. (IIIab) (IIIac) (IIIrd) (IIIae) (IIIth); In the formula, L1, L2, R1, and R2 are each as described in any one of claims 1-15; The addition reaction is a 1,3-dipolar cycloaddition reaction.

17. The preparation method according to claim 16, wherein, The molar ratio of the fullerene to the aniline compound represented by formula (IIIab), (IIIac), (IIIad), (IIIae), or (IIIaf) is 1.1-1.8:

1.

18. The preparation method according to claim 16 or 17, wherein, The aniline compounds represented by formula (IIIab), formula (IIIac), formula (IIIad), formula (IIIae), or formula (IIIaf) are selected from the following compounds: , , , , , , , , , , , .

19. The use of the fullerene-aniline derivative according to any one of claims 1-15, and the fullerene-aniline derivative prepared by the method according to claims 16-18, in the preparation of optoelectronic materials.

20. The application of the fullerene-aniline derivatives according to any one of claims 1-15 and the fullerene-aniline derivatives prepared by the method according to claims 16-18 in the preparation of optoelectronic materials for photoelectric conversion, photoluminescence, molecular sensing, and photocatalytic organic reactions.

21. The use of the fullerene-aniline derivative according to any one of claims 1-15, or the fullerene-aniline derivative prepared by the method according to claims 16-18, in the preparation of solar cells or photocatalytic materials.

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