Self-assembled monolayer with spirofluorene as conjugated bridge, and preparation method and application thereof

Abstract

The application discloses a kind of self-assembly monomolecule with spirofluorene as conjugated bridge and its preparation method and application, it is related to solar cell field, the self-assembly monomolecule with carbazole and its derivative group as functional group, with phosphoric acid as anchor group, by adjusting spirofluorene conjugated bridge, improve the light stability of material, optimize material energy level, improve molecular arrangement.Under the premise of guaranteeing good light stability, the extraction and separation efficiency of carriers are effectively improved.The technology has the characteristics of simple synthesis process and high cost-effectiveness.It can achieve more than 24% photoelectric conversion efficiency when applied to perovskite solar cell, and has great potential in commercial application.

Description

Technical Field

[0001] This invention belongs to the field of solar energy technology and relates to the synthesis of self-assembled molecules, specifically to a self-assembled monomolecule with spirofluorene as a conjugated bridge, its preparation method, and its application in perovskite solar cells. Background Technology

[0002] Perovskite solar cells (PSCs), as an emerging photovoltaic technology, have attracted attention due to their advantages such as simple manufacturing process, easy material adjustment, and cost-effectiveness. PSCs are mainly divided into two structures: nip and pin. The pin structure is more suitable for the production of large-area flexible and tandem solar cells because it can employ low-temperature manufacturing processes and is compatible with various carrier extraction layers, showing greater commercial potential. However, a key issue that needs to be addressed for the pin structure is improving the interfacial contact between the hole-selective layer and the perovskite layer, enhancing charge extraction and transport at the interface, and reducing perovskite defect accumulation. This is crucial for improving the efficiency and long-term stability of perovskite solar cells. Currently, commonly used hole transport materials in pin-structured perovskite solar cells include inorganic nickel oxide (NiO). x Nickel oxide and the organic polymer PTAA are both options. Energy level mismatch and interface defects exist between nickel oxide and perovskite, leading to voltage loss and interface degradation. Furthermore, nickel oxide is a mixture, and its high-valence nickel ions corrode perovskite, reducing the stability of battery devices. PTAA, on the other hand, suffers from high cost, batch-to-batch quality instability, and poor film-forming and wettability, limiting further improvements in battery performance.

[0003] Therefore, developing novel high-performance hole transport materials is crucial for improving the performance of perovskite solar cells (PSCs). Self-assembled monolayers (SAMs), as a type of hole transport material, are mainly composed of carbazole functional groups, alkyl bridging groups, and phosphate anchoring groups. SAM materials have become a popular choice for fabricating high-efficiency PSCs due to their simple structure, flexible design, low optical absorption, low material usage, and compatibility with tandem and flexible perovskite solar cells. Although the widely used PACz series SAMs have high hole extraction capabilities (Joule 2021, 5, 2915-2933), their insulating alkyl bridging bridges exhibit poor stability in high-energy ultraviolet light photons (Angew. Chem. Int. Ed. 2024, 63, e202315281). Therefore, there is an urgent need for a novel SAM material that can effectively extract holes while improving photostability, which is of great significance for promoting the industrialization of PSCs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention aims to provide a co-self-assembled monolayer material that is simple in structure, economical in cost, has high hole transport performance and optical stability, and is suitable for large-scale production.

[0005] To achieve this goal, this invention employs a self-assembled monolayer synthesis strategy to develop a novel self-assembled monolayer material. This material uses carbazole and its derivatives as functional groups and phosphate as an anchoring group. By adjusting the type of conjugated bridges, the self-assembly behavior, energy level modulation, and photothermal stability of the material are optimized. This material design not only ensures good photostability but also improves the interfacial hole selection efficiency, which is of great significance for enhancing the efficiency and device stability of perovskite solar cells. This type of material has the following structural formula:

[0006]

[0007] Where R is a methoxy or alkane group, and the conjugated bridge is a spirofluorene conjugated bridge.

[0008] Furthermore, the self-assembled monomolecular material with spirofluorene as a conjugated bridge is selected from compounds with the following structures:

[0009]

[0010] Where R is a methoxy or alkane group, and the conjugated bridge is a spirofluorene conjugated bridge.

[0011] A further improvement to the present invention is as follows:

[0012] The method for preparing a self-assembled monomolecular material with spirofluorene as a conjugated bridge is characterized by comprising the following steps:

[0013] (a) Compound I undergoes a substitution reaction with a dibromo ring bridge to generate intermediate II;

[0014] (b) React compound II with diethyl phosphite via a substitution reaction to generate intermediate III;

[0015] (c) Cause compound III to undergo a hydrolysis reaction to generate the target product IV, namely a self-assembled monolayer material;

[0016] The reaction equation is shown below:

[0017]

[0018] Where R is a methoxy or alkane group, and the conjugated bridge is a spirofluorene conjugated bridge.

[0019] A further improvement of the present invention is as follows:

[0020] The specific process of step (a) is as follows: Compound I and the dibromo conjugated bridge are dissolved in N,N-dimethylacetamide (DMAC), and a substitution reaction is carried out under the action of base and catalyst to produce intermediate II; the molar ratio of compound I to the dibromo conjugated bridge is 1:1 to 10.

[0021] The specific process of step (b) is as follows: Compound II and diethyl phosphite are heated and reacted under a 1,4-dioxane nitrogen atmosphere. After the reaction is completed, intermediate III is obtained by separation and purification. The molar ratio of compound II to diethyl phosphite is 1:1 to 20.

[0022] In step (c), compound III is mixed with bromotrimethylsilane in dichloromethane and hydrolyzed under a nitrogen atmosphere. After the reaction is completed, the mixture is slurryed and filtered to obtain the target product IV. The molar ratio of compound III to bromotrimethylsilane is 1:5 to 15.

[0023] Furthermore, in step (a), the base used is potassium hydroxide or potassium carbonate, the catalyst is cuprous iodide, the reaction temperature is 100-200℃, and the reaction time is 4-12 hours; in step (b), the reaction temperature is 100-110℃ and the time is 4-15 hours; in step (c), the reaction temperature is 10-100℃ and the time is 4-15 hours.

[0024] The above-mentioned application of a self-assembled monolayer material with spirofluorene as a conjugate bridge in perovskite solar cells.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. The present invention provides a self-assembled monolayer material with spirofluorene as a conjugated bridge. Carbazole and its derivative groups, as well as the conjugated bridge groups, are all conjugated units, which have good ultraviolet light resistance and can effectively improve the photostability of the material.

[0027] 2. This type of self-assembled monolayer material with spirofluorene as a conjugated bridge has a large conjugated planar structure, which enhances the intermolecular interaction and enables molecules to form an ordered and compact self-assembled monolayer (SAM) on the ITO substrate, which is beneficial for interfacial charge extraction and transport.

[0028] 3. The application of a self-assembled monolayer material with spirofluorene as a conjugate bridge provided by this invention in perovskite solar cells has achieved a photoelectric conversion efficiency of over 24% and exhibited good photothermal stability, which helps to promote the commercial development of perovskite solar cells. Attached Figure Description

[0029] Figure 1 The molecular structure of a self-assembled monomolecule material with spirofluorene as a conjugated bridge prepared in this invention;

[0030] Figure 2 The NMR spectrum of Me-CzF prepared according to this invention;

[0031] Figure 3 The NMR spectrum of the MeO-CzF prepared according to this invention;

[0032] Figure 4 The NMR spectrum of the MeO-CzSFO prepared according to this invention;

[0033] Figure 5 JV curve of perovskite solar cells prepared using the Me-CzF material of this invention as a self-assembled monolayer material;

[0034] Figure 6 JV curve of perovskite solar cells prepared using the MeO-CzF formula prepared in this invention as a self-assembled monolayer material;

[0035] Figure 7 JV curve of perovskite solar cells prepared by MeO-CzSFO as a self-assembled monolayer material in this invention. Detailed Implementation

[0036] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention is provided in conjunction with the accompanying drawings and preferred embodiments.

[0037] This invention employs a self-assembled monolayer synthesis strategy to develop a novel self-assembled monolayer material. The molecular structure of the material is as follows: Figure 1 As shown.

[0038] The following will take the formulas Me-CzF, MeO-CzF, and MeO-CzSFO as examples for detailed introduction.

[0039] Example 1: Synthesis of self-assembled monolayer material Me-CzF

[0040] The synthesis route is as follows:

[0041]

[0042] Synthesis of compound 3:

[0043] To a 100 mL single-necked round-bottom flask, add starter 1 (1 g, 4.2 mmol), 2-bromo-7-iodo-9,9-dimethylfluorene (3 g, 7.6 mmol), cuprous iodide (260 mg, 1.4 mmol), potassium carbonate (1 g), and solvent DMAC (15 mL) sequentially. Heat the mixture to 150 °C and reflux for 24 h. After cooling to room temperature, extract with dichloromethane and water. Distill the organic phase under reduced pressure. Separately analyze the crude product by column chromatography (eluent: petroleum ether / dichloromethane = 50 / 1 to 10 / 1) to give 1.86 g of the compound shown in Formula 3 as a white solid, in 70% yield. 1 H NMR (400MHz, CDCl3) δ7.95 (s, 2H), 7.89 (d, J = 7.9Hz, 1H), 7.69-7.60 (m, 3H), 7.58 -7.52(m,2H),7.38(d,J=8.3Hz,2H),7.30-7.24(m,2H),2.59(s,6H),1.57(s,6H).

[0044] Synthesis of compound 4:

[0045] Intermediate 3 (1 g, 2.2 mmol), palladium acetate (50 mg, 0.22 mmol), dppf (122 mg, 0.22 mmol), potassium acetate (660 mg, 6.6 mmol), and diethyl phosphite (165 mg, 1.2 mmol) were added sequentially to a 100 mL double-necked flask. 15 mL of 1,4-dioxane was added as solvent, and the mixture was heated to 110 °C for 10 h. After the reaction solution cooled to room temperature, dichloromethane and water were added for extraction. The organic phase was distilled under reduced pressure, and the crude product was subjected to column chromatography (eluent: petroleum ether / dichloromethane = 10 / 1 to 1 / 2) to give 0.9 g of intermediate 4, a white solid, in 80% yield. 1 H NMR (400MHz, CDCl3) δ8.01-7.94(m,4H),7.90-7.82(m,2H),7.67(d,J=1.8Hz,1H),7.59(dd,J=8.1,2.0Hz,1H) ,7.39(d,J=8.3Hz,2H),7.29-7.24(m,3H),4.29-4.11(m,4H),2.58(s,6H),1.59(s,6H),1.40(t,J=7.0Hz,6H).

[0046] Synthesis of Me-CzF:

[0047] Under nitrogen protection, intermediate 4 (100 mg, 0.2 mmol), trimethylbromosilane (367 mg, 0.32 mL), and 10 mL of dichloromethane were added sequentially to a 100 mL two-necked flask. The mixture was reacted at room temperature for 10 h. The solvent was removed by vacuum distillation, and the product was slurryed to obtain a white solid. 70 mg of product was obtained, with a yield of 75%. The 1H NMR spectrum is attached. Figure 2 As shown. 1 H NMR (400MHz, CDCl3) δ7.91 (s, 5H), 7.59 (d, J = 39.7Hz, 2H), 7.31 (d, J = 20.9Hz, 3H), 7.18 (t, J = 9.8Hz, 2H), 2.53 (s, 6H).

[0048] Example 2: Synthesis of self-assembled monolayer material MeO-CzF

[0049] The synthesis route is as follows:

[0050]

[0051] Synthesis of compound 6:

[0052] To a 100 mL single-necked round-bottom flask, add starting material 5 (1 g, 4.4 mmol), 2-bromo-7-iodo-9,9-dimethylfluorene (1.6 g, 6.6 mmol), cuprous iodide (860 mg, 4.6 mmol), potassium carbonate (1 g), and solvent DMAC (15 mL) sequentially. Heat the mixture to 180 °C and reflux for 12 h. After cooling to room temperature, extract with dichloromethane and water. Distill the organic phase under reduced pressure. Separately analyze the crude product by column chromatography (eluent: petroleum ether / dichloromethane = 50 / 1 to 10 / 1) to give 0.8 g of the compound shown in Formula 6 as a white solid, in 70% yield. 1 H NMR(400MHz, CDCl3)δ7.88(d,J=7.9Hz,1H),7.68-7.59(m,5H),7.54(dt,J=8.1,1.5H z, 2H), 7.41 (d, J = 8.9Hz, 2H), 7.09 (dd, J = 8.9, 2.4Hz, 2H), 3.99 (s, 6H), 1.57 (s, 6H).

[0053] Synthesis of compound 7:

[0054] Intermediate 6 (1 g, 2 mmol), palladium acetate (70 mg, 0.3 mmol), dppf (55 mg, 0.1 mmol), potassium acetate (600 mg, 6 mmol), and diethyl phosphite (165 mg, 1.2 mmol) were added sequentially to a 100 mL double-necked flask. 15 mL of 1,4-dioxane was added as solvent, and the mixture was heated to 110 °C and reacted for 10 h. After the reaction mixture cooled to room temperature, dichloromethane and water were added for extraction. The organic phase was distilled under reduced pressure, and the crude product was subjected to column chromatography (eluent: petroleum ether / dichloromethane = 10 / 1 to 1 / 2) to give 0.88 g of intermediate 7, a white solid, in 80% yield. 1 H NMR (400MHz, CDCl3) δ8.00-7.95(m,2H),7.90-7.82(m,2H),7.66(d,J=2.0Hz,1H),7.61-7.55(m,3H),7.41(d, J=8.9Hz,2H),7.09(dd,J=8.9,2.6Hz,2H),4.30-4.13(m,4H),3.99(s,6H),1.60(s,6H),1.40(t,J=7.0Hz,6H).

[0055] Synthesis of MeO-CzF:

[0056] Under nitrogen protection, intermediate 7 (200 mg, 0.36 mmol), trimethylbromosilane (634 mg, 0.55 mL), and 10 mL of dichloromethane were added sequentially to a 100 mL two-necked flask. The mixture was reacted at room temperature for 10 h. The solvent was removed by vacuum distillation, and the product was slurryed to obtain a white solid. The product yield was 140 mg, 75%. The 1H NMR spectrum is attached. Figure 3 As shown. 1 H NMR (400MHz, DMSO) δ8.13(d,J=8.1Hz,1H),8.01(dd,J=7.7,3.1Hz,1H),7.91-7.83(m,4H),7.74(ddd,J=12.7, 7.7, 1.3Hz, 1H), 7.59 (dd, J = 8.1, 2.0Hz, 1H), 7.38 (d, J = 8.9Hz, 2H), 7.07 (dd, J = 8.9, 2.6Hz, 2H), 3.88 (s, 6H).

[0057] Example 3: Synthesis of self-assembled monolayer material MeO-CzSFO

[0058] The synthesis route is as follows:

[0059]

[0060] Synthesis of compound 9:

[0061] To a 100 mL single-necked round-bottom flask, add starting material 5 (1 g, 4.4 mmol), 2,7-dibromospiro(fluorene-9,9-oxanthracene) (3.2 g, 6.6 mmol), cuprous iodide (230 mg, 1.3 mmol), potassium carbonate (1 g), and solvent DMAC (15 mL) sequentially. Heat the mixture to 180 °C and reflux for 18 h. After cooling to room temperature, extract with dichloromethane and water. Distill the organic phase under reduced pressure. Separately analyze the crude product by column chromatography (eluent: petroleum ether / dichloromethane = 50 / 1–10 / 1) to give 1.8 g of compound 9 as a white solid, in 70% yield. 1 H NMR (400MHz, CDCl3) δ7.97(d,J=8.1Hz,1H),7.73(d,J=8.1Hz,1H),7.61(dd,J=8.1,2.0Hz,1H) ,7.59-7.54(m,1H),7.51(d,J=2.4Hz,2H),7.37(t,J=2.0Hz,2H),7.28(s,1H),7.27(d,J=1.6Hz ,1H),7.26(s,2H),7.18(s,1H),7.16(s,1H),6.97(d,J=2.6Hz,1H),6.95(d,J=2.6Hz,1H),6.9 1(ddd,J=7.8,6.4,2.1Hz,2H),6.60-6.55(m,2H),3.94(s,6H),1.41(s,1H),1.33-1.27(m,4H).

[0062] Synthesis of compound 10:

[0063] Intermediate 9 (1 g, 1.5 mmol), palladium acetate (11 mg, 0.05 mmol), dppf (170 mg, 0.3 mmol), potassium acetate (450 mg, 4.5 mmol), and diethyl phosphite (125 mg, 0.9 mmol) were added sequentially to a 100 mL double-necked flask. 15 mL of 1,4-dioxane was added as solvent, and the mixture was heated to 110 °C for 10 h. After the reaction solution cooled to room temperature, dichloromethane and water were added for extraction. The organic phase was distilled under reduced pressure, and the crude product was subjected to column chromatography (eluent: petroleum ether / dichloromethane = 10 / 1 to 1 / 2) to give 0.8 g of intermediate 10, a white solid, in 80% yield. 1H NMR (400MHz, DMSO) δ8.38(d,J=8.2Hz,1H),8.27(dd,J=7.9,2.8Hz,1H),7.80-7.73(m,4H),7.41-7.30(m,7H),7. 11(d,J=8.9Hz,2H),6.99-6.91(m,4H),6.51-6.47(m,2H),4.00-3.90(m,4H),3.85(s,6H),1.13(t,J=7.1Hz,7H).

[0064] Synthesis of MeO-CzSFO:

[0065] Under nitrogen protection, intermediate 10 (100 mg, 0.14 mmol), trimethylbromosilane (254 mg, 0.22 mL), and 10 mL of dichloromethane were added sequentially to a 100 mL two-necked flask. The mixture was reacted at room temperature for 10 h. The solvent was removed by vacuum distillation, and the product was slurryed to obtain a white solid. 70 mg of product was obtained, with a yield of 76%. The 1H NMR spectrum is attached. Figure 4 As shown. 1 H NMR (400MHz, DMSO) δ8.34(d,J=8.1Hz,1H),8.18(dd,J=7.8,2.9Hz,1H),7.85-7.70(m,4H),7. 46-7.23(m,6H),7.12(d,J=8.9Hz,2H),7.02-6.88(m,4H),6.49(d,J=7.3Hz,2H),3.84(s,6H).

[0066] Example 4: This example provides an application of the Me-CzF compound prepared in Example 1 in the fabrication of perovskite solar cells. Test light source: AM 1.5 (solar simulator-Oriel 91160-1000, 300W), data acquisition using a Keithley 2400 digital source meter. Test results are attached. Figure 5 The short-circuit photocurrent density of the battery device reached 25.62 mA cm⁻¹. -2 The open-circuit voltage is 1.195V, the fill factor (FF) is 0.791, and the photoelectric conversion efficiency reaches 24.22%.

[0067] Example 5: This example provides an application of the MeO-CzF compound prepared in Example 2 in the fabrication of perovskite solar cells. Test light source: AM 1.5 (solar simulator-Oriel 91160-1000, 300W), data acquisition using a Keithley 2400 digital source meter. Test results are attached. Figure 6The short-circuit photocurrent density of the battery device reached 25.38 mA / cm². -2 The open-circuit voltage is 1.195V, the fill factor (FF) is 0.796, and the photoelectric conversion efficiency reaches 24.14%.

[0068] Example 6: This example provides an application of the MeO-CzF compound prepared in Example 3 in the fabrication of perovskite solar cells. Test light source: AM 1.5 (solar simulator-Oriel 91160-1000, 300W), data acquisition using a Keithley 2400 digital source meter. Test results are attached. Figure 7 The short-circuit photocurrent density of the battery device reached 25.51 mA / cm². -2 The open-circuit voltage is 1.194V, the fill factor (FF) is 0.805, and the photoelectric conversion efficiency reaches 24.52%.

[0069] This method is merely intended to illustrate the technical concepts and characteristics of the present invention, enabling those skilled in the art to understand and implement it, and is not intended to limit the scope of protection of the present invention. Any equivalent substitutions or adjustments based on the core concepts of the present invention should be included within the scope of protection of the present invention.

Claims

1. A self-assembled monolayer material with spirofluorene as a conjugated bridge, characterized in that, The general structural formula is as follows: ； Compounds selected from the following structures: ； Where R is a methoxy or alkane group, and the conjugated bridge is a spirofluorene conjugated bridge.

2. The method for preparing a self-assembled monolayer material with spirofluorene as a conjugate bridge as described in claim 1, characterized in that, Includes the following steps: (a) Compound I undergoes a substitution reaction with a dibromospirofluorene conjugate bridge to generate intermediate II; (b) To induce a substitution reaction between compound II and diethyl phosphite to generate intermediate III; (c) Cause compound III to undergo a hydrolysis reaction to generate the target product IV, i.e., a self-assembled monolayer material; The reaction equation is shown below. ； Where R is a methoxy or alkane group, and the conjugated bridge is a spirofluorene conjugated bridge.

3. The method for preparing a self-assembled monolayer material with spirofluorene as a conjugate bridge according to claim 2, characterized in that: The specific process of step (a) is as follows: Compound I and the dibromo conjugated bridge are dissolved in N,N-dimethylacetamide (DMAC), and a substitution reaction is carried out under the action of a base and a catalyst to produce intermediate II; the molar ratio of compound I to the dibromo conjugated bridge is 1:1~10.

4. The method for preparing a self-assembled monolayer material with spirofluorene as a conjugate bridge according to claim 2, characterized in that: The specific process of step (b) is as follows: Compound II and diethyl phosphite are heated and reacted under a 1,4-dioxane nitrogen atmosphere. After the reaction is completed, intermediate III is obtained by separation and purification. The molar ratio of compound II to diethyl phosphite is 1:1 to 20.

5. The self-assembled monolayer material with spirofluorene as a conjugate bridge according to claim 2, characterized in that: In step (c), compound III is mixed with bromotrimethylsilane in dichloromethane and hydrolyzed under a nitrogen atmosphere. After the reaction is completed, the mixture is slurryed and filtered to obtain the target product IV. The molar ratio of compound III to bromotrimethylsilane is 1:5~15.

6. A method for preparing a self-assembled monolayer material with spirofluorene as a conjugate bridge according to any one of claims 2 to 5, characterized in that: The base used in step (a) is potassium hydroxide or potassium carbonate, the catalyst is cuprous iodide, the reaction temperature is 100~200 ℃, and the reaction time is 4~12 hours; the reaction temperature in step (b) is 100-110 ℃, and the time is 4-15 h; the reaction temperature in step (c) is 10-100 ℃, and the time is 4-15 h.

7. The application of the self-assembled monolayer material with spirofluorene as a conjugate bridge as described in claim 1 in perovskite solar cells.

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