A benzotriazole derivative electron acceptor, and a preparation method and use thereof

Abstract

The application discloses a benzotriazole derivative electron acceptor and a preparation method and application thereof. The benzotriazole derivative electron acceptor is represented by a general formula (I). The acceptor has good solubility in green solvents, and can be processed into an organic solar cell and a transparent organic solar cell with high energy conversion efficiency in combination with a polymer donor.

Description

Technical Field

[0001] This invention relates to the field of organic photovoltaic technology, and more particularly to a benzotriazole derivative electron acceptor, its preparation method, and its use in organic solar cells. Background Technology

[0002] Organic solar cells are a photovoltaic technology with enormous application potential in fields such as building-integrated photovoltaics and wearable electronics. In recent years, thanks to the development of donor and acceptor materials and the optimization of device engineering, the efficiency of organic solar cells has exceeded 21%. However, these high-efficiency cells typically rely on processing with halogen-containing solvents, which does not meet the requirements for commercial applications. Strategies for designing near-infrared absorber acceptors that can be processed with low-toxicity organic solvents (also known as green solvents, such as toluene and o-xylene) mainly focus on side chain engineering modifications, such as extending side chains, changing the branch positions of alkyl chains, and introducing oligoethylene glycol chains (OEG chains). OEG side chains have advantages such as polarity and flexibility, and can adjust molecular conformation and solubility in high-boiling-point solvents. This characteristic has been widely used in recent years for high-efficiency, green solvent-processed organic solar cells. However, most of these electron acceptors are based on a seven-membered fused ring structure, resulting in high synthesis costs. They also exhibit absorption in the visible light range of 400-600 nm and have a wide half-width at half-maximum (HWHM), which is not conducive to the fabrication of high-transparency organic solar cells. In conclusion, high-efficiency, convenient, and green solvent-based electron acceptors that meet practical application requirements are still very scarce and warrant further exploration. Summary of the Invention

[0003] To address the shortcomings of existing technologies, one objective of this invention is to provide a benzotriazole derivative electron acceptor that exhibits good solubility in green solvents and, when combined with a polymer donor, can be processed into high-energy-conversion-efficiency organic solar cells and transparent organic solar cells.

[0004] The technical solution of the present invention is as follows:

[0005] According to one aspect of the present invention, a benzotriazole derivative electron acceptor having the structure shown in general formula (I) is provided.

[0006]

[0007] R1 and R2 are each independently C1-C20 branched or straight-chain saturated alkyl groups;

[0008] Preferably, R1 and R2 are each independently a C4-C16 branched or straight-chain saturated alkyl group;

[0009] More preferably, R1 and R2 are each independently C6-C14 branched or straight-chain saturated alkyl groups;

[0010] More preferably, R1 is a C6-C10 branched or straight-chain saturated alkyl group, and R2 is a C8-C14 branched or straight-chain saturated alkyl group;

[0011] More preferably, R1 and R2 are each independently... or .

[0012] More preferably, the electron acceptor structure of the benzotriazole derivative shown in Formula I is as follows:

[0013]

[0014] According to another aspect of the invention, the invention also provides the application of the benzotriazole derivative electron acceptor shown in Formula I in organic solar cells.

[0015] According to another aspect of the present invention, an organic solar cell is also provided, comprising a substrate, an anode, a hole transport layer, an active layer, an electron transport layer, and a cathode, wherein the active layer comprises a benzotriazole derivative electron acceptor and a polymer donor as shown in Formula I.

[0016] Preferably, the polymer donor in the active layer is PTB7-Th, with the following structural formula:

[0017]

[0018] Preferably, the mass ratio of PTB7-Th to benzotriazole derivative electron acceptor in the active layer of the organic solar cell is 1:5 to 3:1, and the thickness of the active layer is 30 to 300 nm.

[0019] Preferably, the substrate of the organic solar cell is glass; the anode is ITO; the hole transport layer is poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS); the electron transport layer is PDINN or ZnO; and the cathode is Ag or AgNWs.

[0020] Preferably, when ZnO is used as the electron transport layer and AgNWs are used as the cathode, the organic solar cell is a transparent organic solar cell. Using AgNWs as a transparent electrode can greatly improve the average visible light transmittance of the organic solar cell.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] The benzotriazole derivative electron acceptor in this invention exhibits excellent solubility in green solvents. Therefore, organic solar cells fabricated using this acceptor and the narrow-bandgap polymer donor PTB7-Th as the active layer can be processed with low-toxicity green solvents and achieve high power conversion efficiency. Furthermore, transparent organic solar cells fabricated with this active layer achieve high power conversion efficiency while maintaining high average visible light transmittance. The benzotriazole derivative electron acceptor prepared in this invention has great application potential in the field of transparent organic solar cells. Attached Figure Description

[0023] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0024] Figure 1 The UV-Vis absorption spectra of PTB7-Th and BZ-OEG prepared in Example 2 in the thin film state are shown.

[0025] Figure 2 The current density-voltage (JV) curves of the organic solar cell prepared in Example 3 based on the PTB7-Th:BZ-OEG active layer were measured at AM1.5G. In the figure, Voc is the open-circuit voltage, Jsc is the short-circuit current density, FF is the fill factor, and PCE is the photoelectric conversion efficiency.

[0026] Figure 3 The current density-voltage (JV) curve of the transparent organic solar cell prepared in Example 4 based on the PTB7-Th:BZ-OEG active layer was measured at AM 1.5G, where AVT stands for average transmittance. Detailed Implementation

[0027] The present invention will now be described in detail. Before proceeding with the description, it should be understood that the terminology used in this specification and the appended claims should not be construed as limited to its general or dictionary meaning, but rather should be interpreted according to the meaning and concept corresponding to the technical aspects of the invention, based on the principle that the inventors are allowed to appropriately define the terms for the best interpretation. Therefore, the description presented herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of the invention. It should be understood that other equivalents or modifications can be obtained from it without departing from the spirit and scope of the invention.

[0028] In this document, the terms “comprising,” “including,” “having,” “containing,” or any other similar terms are open-ended conjunctions intended to cover non-exclusive inclusions. For example, a composition or article containing a plurality of elements is not limited to those listed herein, but may also include other elements not explicitly listed but typically inherent to the composition or article. Furthermore, unless explicitly stated to the contrary, the term “or” is inclusive, not exclusive. For example, the condition “A or B” is satisfied in any of the following cases: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); A and B are both true (or exist). Moreover, in this document, the terms “comprising,” “including,” “having,” and “containing” should be interpreted as specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as “composed of” and “substantially composed of.”

[0029] In this document, all features or conditions defined in the form of numerical ranges or percentage ranges are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible secondary ranges and individual values ​​within those ranges, particularly integer values. For example, a range description of "1 to 8" should be considered as specifically disclosing all secondary ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., particularly secondary ranges defined by all integer values, and should be considered as specifically disclosing individual values ​​within those ranges such as 1, 2, 3, 4, 5, 6, 7, 8, etc. Unless otherwise specified, the foregoing interpretation applies to all content throughout this invention, regardless of its scope.

[0030] If a quantity or other numerical value or parameter is expressed as a range, a preferred range, or a series of upper and lower limits, it should be understood that this document has specifically disclosed all ranges consisting of any upper or preferred value of that range and the lower or preferred value of that range, regardless of whether such ranges are separately disclosed. Furthermore, when a range of numerical values ​​is mentioned herein, unless otherwise stated, the range shall include its endpoints and all integers and fractions within the range.

[0031] In this document, numerical values ​​are to be understood as having a precision with significant digits, provided that the purpose of the invention can be achieved. For example, the number 40.0 should be understood to cover a range from 39.50 to 40.49.

[0032] The following examples further illustrate specific implementations of the present invention, but the implementation and protection of the present invention are not limited thereto. It should be noted that any processes not specifically described below are those that can be implemented or understood by those skilled in the art by referring to existing technology. Furthermore, unless otherwise stated, the reagents and solvents disclosed below were purchased from Shanghai Bieder Pharmaceutical Technology Co., Ltd.1 H NMR was measured using a Bruker AV-500 / 600 / 800 MHz NMR spectrometer; UV-Vis absorption spectroscopy was measured using an Agilent Cary 6000i; and current density-voltage (JV) curves were measured using a Keithley 2400 semiconductor characterization system.

[0033] Example 1: Synthesis of benzotriazole derivative electron acceptor (BZ-OEG)

[0034]

[0035] Compound 1 can be synthesized according to the methods described in the literature (ACS Macro Lett. 2023, 12, 503-509; or CN113880862 A).

[0036] Step 1: Synthesis of Compound 2:

[0037] 1.12 g of tributyl(4-(2-ethylhexyl)thiophen-2-yl)stanane (2.3 mmol), 19 mg of Pd2(dba)3 (0.02 mmol), and 25 mmol of tris(2-methylphenyl)phosphine (0.08 mmol) were added to 10 mL of a toluene solution of compound 1 (1 mmol). The mixture was heated to 90 °C and stirred for 4 hours under a nitrogen atmosphere. After cooling to room temperature, the mixture was extracted with dichloromethane and the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using n-hexane / ethyl acetate (3:1, v / v) as eluent, and dried under vacuum to give a yellow liquid compound 2 in 92% yield. 1 H NMR (600 MHz, CDCl3) δ 7.25–7.22 (m, 2H),7.16–7.14 (m, 2H), 4.93 (t, J =5.6, 2H), 4.14 (t, J =5.6, 2H), 3.58–3.54 (m, 2H), 3.42–3.38 (m, 2H), 3.24 (s, 3H), 2.53 (d, J =6.8, 4H), 1.52–1.48 (m, 2H), 1.26–1.19 (m, 16H), 0.83 (t, J =7.4, 12H).

[0038] Step 2: Synthesis of Compound 3:

[0039] 699 mg of compound 2 (1 mmol) and 2.62 g of triphenylphosphine (10 mmol) were dissolved in 6 mL of o-dichlorobenzene (DCB). The reaction mixture was heated to 180°C and stirred for 4 hours under a nitrogen atmosphere. After the reaction was completed, the mixture was cooled to room temperature, and the solvent was removed under reduced pressure to obtain the crude product compound 3, which was used directly in the next reaction without further purification.

[0040] Step 3: Synthesis of Compound 4:

[0041] Compound 3 (1 mmol), 2 g of 5-(bromomethyl)undecane (8 mmol), and 320 mg of NaOH (8 mmol) were dissolved in 10 mL of N,N-dimethylformamide (DMF). The reaction mixture was heated to 85°C and stirred for 8 hours under a nitrogen atmosphere. After the reaction was completed, the mixture was cooled to room temperature, extracted with dichloromethane, and the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using n-hexane / ethyl acetate (6:1, v / v) as eluent, and dried under vacuum to give compound 4 as a yellow liquid in 44% yield. 1 H NMR (600 MHz, CDCl3) δ 6.95 (s, 2H), 5.00 (t, J =6.3, 2H), 4.52–4.33 (m,4H), 4.25 (t, J =6.2, 2H), 3.66–3.59 (m, 2H), 3.51–3.47 (m, 2H), 3.33 (s, 3H), 3.01–2.64 (m, 4H), 1.92–1.82 (m, 2H), 1.76–1.69 (m, 2H), 1.55–0.16 (m, 72H).

[0042] Step 4: Synthesis of Compound 5:

[0043] 400 mg of compound 4 (0.41 mmol) and 0.35 mL of DMF were dissolved in 15 mL of dichloroethane (DCE). Under ice bath conditions, 0.38 mL of POCl3 was added and the mixture was stirred at this temperature for 40 minutes. The temperature was then raised to 85°C and the reaction was stirred for 6.5 hours. After the reaction was complete, the mixture was cooled to room temperature, and 5 mL of saturated K₂CO₃ solution was added and the mixture was stirred for 3 hours. The mixture was extracted with dichloromethane and the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using n-hexane / ethyl acetate (3:1, v / v) as eluent, and dried under vacuum to give an orange liquid compound 5 in 90% yield. 1 H NMR (600 MHz, CDCl3) δ 10.12 (s, 2H),5.00 (t, J=6.0, 2H), 4.54–4.39 (m, 4H), 4.26 (t, J =6.0, 2H), 3.71–3.62 (m, 2H), 3.54–3.49 (m, 2H), 3.46–3.36 (m, 2H), 3.33 (s, 3H), 3.02–2.91 (m, 2H), 1.95–1.84 (m, 2H), 1.78–1.68 (m, 2H), 1.60–0.08 (m, 72H).

[0044] Step 5: Synthesis of Compound 6:

[0045] 332 mg ((1,3-dioxolane-2-yl)methyl)tributylphosphonium bromide (0.90 mmol) was added to 20 mL of a tetrahydrofuran solution of compound 5 (168 mg, 0.35 mmol). Then, 69.0 mg NaH (60% dispersed in mineral oil) (1.74 mmol) was added, and the reaction mixture was stirred at room temperature under a nitrogen atmosphere for 16 hours. Subsequently, 3 mL of 10% HCl was added, and stirring continued at room temperature for 3 hours. Extraction was performed with dichloromethane, and the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using n-hexane / ethyl acetate (3:1, v / v) as eluent, and dried under vacuum to give a red liquid compound 6 in 76% yield. 1 H NMR (500MHz, CDCl3) δ 9.68 (d, J =7.6, 2H), 7.78 (d, J =15.2, 2H), 6.61 (dd, J =15.1, 7.5,2H), 5.01 (t, J =5.9, 2H), 4.48–4.37 (m, 4H), 4.26 (t, J =5.3, 2H), 3.69–3.62 (m,2H), 3.55–3.47 (m, 2H), 3.34 (s, 3H), 3.10–2.86 (m, 4H), 1.91–1.79 (m, 2H),1.77–1.67 (m, 2H), 1.38–0.07 (m, 72H).

[0046] Step 6: Synthesis of BZ-OEG:

[0047] 170 mg of compound 6 (0.16 mmol), 109 mg of 5,6-difluoro-3-(dicyanomethylene)indophenone (0.47 mmol), 0.2 mL of acetic anhydride, and 0.2 mL of boron trifluoride diethyl ether were dissolved in 10 mL of toluene. The reaction mixture was stirred at room temperature for 2 hours. After the reaction was complete, the mixture was extracted with dichloromethane and the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using chloroform / tetrahydrofuran (110:1, v / v) as eluent, and dried under vacuum to give a black solid BZ-OEG in 81% yield. 1 HNMR (600 MHz, CDCl3) δ 8.76–8.69 (m, 2H), 8.56–8.47 (m, 4H), 7.75 (d, J =14.3,2H), 7.68 (t, J =7.4, 2H), 5.04 (t, J =6.0, 2H), 4.50–4.36 (m, 4H), 4.35–4.28 (m,2H), 3.77–3.68 (m, 2H), 3.59–3.52 (m, 2H), 3.37 (s, 3H), 3.13–3.01 (m, 2H), 3.00–2.88 (m, 2H), 1.89–1.78 (m, 2H), 1.77–1.70 (m, 2H), 1.59–1.17 (m, 36H), 1.06–0.77 (m, 20H), 0.68–0.14 (m, 16H).

[0048] Example 2: UV-Vis absorption spectroscopy of benzotriazole derivative electron acceptor (BZ-OEG)

[0049] The benzotriazole derivative electron acceptor (BZ-OEG) prepared in Example 1 was dissolved in o-xylene to prepare a solution with a concentration of 10 mg / mL. This solution was then spin-coated onto a quartz plate at 2500 rpm to form a thin film sample, and the absorption of the film was measured using a UV-Vis absorption spectrometer. The absorption spectrum of BZ-OEG in the thin film is shown below. Figure 1 As shown in the figure. The results show that the maximum absorption peak of BZ-OEG is at 893 nm, the absorption onset edge is at 1007 nm, and the optical band gap is 1.23 eV.

[0050] Example 3: Fabrication and Performance Testing of Organic Solar Cells Based on PTB7-Th:BZ-OEG Active Layer

[0051] The device structure is ITO / PEDOT:PSS / PTB7-Th:BZ-OEG / PDINN / Ag.

[0052] The preparation process was as follows: Strips of etched ITO (indium tin oxide) glass were sequentially ultrasonically cleaned in a cleaning agent, deionized water, and ethanol, then dried by nitrogen purging and subjected to plasma treatment for 2 minutes. PEDOT:PSS (diluted with deionized water to a mass percentage concentration of 50%) was spin-coated onto the ITO substrate at 4000 rpm and annealed at 150°C for 2 minutes. The wafer was then transferred to a glove box under a nitrogen atmosphere. In the glove box, PTB7-Th and BZ-OEG (mass ratio 1:1.7) were dissolved in o-xylene to prepare an active layer solution with a PTB7-Th donor concentration of 7.4 mg / mL. This solution was stirred at 60°C for 4 hours, and the substrate was preheated to 100°C for 10 minutes on a hot plate before spin-coating the active layer. The substrate was then spin-coated onto the PEDOT:PSS layer at 2500 rpm and annealed at 100°C for 5 minutes. A 1 mg / mL PDINN solution was spin-coated onto the active layer at 4000 rpm. Finally, 100 nm of Ag was deposited onto the PDINN layer via thermal vacuum evaporation. The effective area of ​​the device was defined as 0.03 cm² using a shadow mask. 2 The fabricated device was named PTB7-Th:BZ-OEG.

[0053] Under simulated sunlight (AM 1.5G, 100mW / cm²) 2 The current density-voltage (JV) curve of the test device under irradiation. Figure 2 As shown, the open-circuit voltage of the PTB7-Th:BZ-OEG device is 0.617V, and the short-circuit current is 26.9mA / cm. 2 The fill factor is 70.2% and the energy conversion efficiency is 11.7%.

[0054] Example 4: Fabrication and Performance Testing of Transparent Organic Solar Cells Based on PTB7-Th:BZ-OEG Active Layer

[0055] The device structure is ITO / PEDOT:PSS / PTB7-Th:BZ-OEG / ZnO / AgNWs.

[0056] The preparation process was as follows: ITO (indium tin oxide) glass with etching was sequentially ultrasonically cleaned in a cleaning agent, deionized water, and ethanol, then dried by nitrogen purging and subjected to plasma treatment for 2 minutes. PEDOT:PSS (diluted with deionized water to a mass percentage concentration of 50%) was spin-coated onto the ITO substrate at 4000 rpm and annealed at 150°C for 2 minutes. The wafer was then transferred to a glove box under a nitrogen atmosphere. In the glove box, PTB7-Th and BZ-OEG (mass ratio 1:1.7) were dissolved in o-xylene to prepare an active layer solution with a PTB7-Th donor concentration of 5.9 mg / mL, with 70% (mass fraction relative to acceptor mass) of phenanthrene added as an additive. This solution was stirred at 60°C for 4 hours, and the substrate was preheated to 100°C on a hot plate for 10 minutes before spin-coating the active layer. Subsequently, the active layer solution was spin-coated onto the PEDOT:PSS layer and annealed at 100°C for 5 minutes. To ultimately fabricate a transparent organic solar cell with an average visible light transmittance of approximately 70%, the active layer thickness was controlled to approximately 63 nm. The wafer was then transferred back to air, and 3–4 layers of ZnO (10 mg / mL) were spin-coated onto the active layer at 4000 rpm. Finally, AgNWs were deposited on the ZnO layer at a spin speed of 2500 rpm. The effective area of ​​the device was defined as 0.03 cm by a shadow mask. 2 .

[0057] Under simulated sunlight (AM 1.5G, 100mW / cm²) 2 The current density-voltage (JV) curve of the test device under irradiation. Figure 3 As shown, the transparent device fabricated based on the PTB7-Th:BZ-OEG active layer has an open-circuit voltage of 0.594V and a short-circuit current of 13.0mA / cm. 2 The fill factor is 56.1%, and the energy conversion efficiency is 4.32%. The average visible light transmittance is 70.1%, and the light utilization efficiency is 3.03%.

[0058] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A benzotriazole derivative electron acceptor having the structure shown in general formula (I), ； in, R1 and R2 are each independently C6-C14 branched or straight-chain saturated alkyl groups.

2. The benzotriazole derivative electron acceptor according to claim 1, characterized in that, R1 and R2 are each independent of each other. or .

3. The benzotriazole derivative electron acceptor according to claim 1, characterized in that, The electron acceptor structure of the benzotriazole derivative shown in Formula I is as follows: 。 4. The application of the benzotriazole derivative electron acceptor according to any one of claims 1 to 3 in organic solar cells.

5. An organic solar cell comprising a substrate, an anode, a hole transport layer, an active layer, an electron transport layer, and a cathode, wherein, The active layer includes an electron acceptor and a polymer donor of the benzotriazole derivative of Formula I as described in any one of claims 1 to 3.

6. The organic solar cell according to claim 5, characterized in that, The polymer donor in the active layer is PTB7-Th, and its structural formula is: ； The active layer of the organic solar cell has a PTB7-Th to benzotriazole derivative electron acceptor mass ratio of 1:5 to 3:1, and the active layer thickness is 30 to 300 nm.

7. The organic solar cell according to claim 5, characterized in that, The substrate of the organic solar cell is glass; the anode is ITO; the hole transport layer is poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate); the electron transport layer is PDINN or ZnO; and the cathode is Ag or AgNWs.

8. The organic solar cell according to claim 7, characterized in that, The electron transport layer is ZnO, and the cathode is AgNWs.

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