A phenoxazine derivative ultra-narrow band gap acceptor, a preparation method thereof and use thereof in organic solar cells

Abstract

The application discloses a kind of with phenoxazine structure as core's ultra-narrow band gap electron acceptor represented by formula (I), and preparation method and the use of the acceptor in organic solar cell.The phenoxazine derivative ultra-narrow band gap acceptor in the application has very low thin film optical band gap (about 1.2eV).The organic solar cell prepared by matching with narrow band gap polymer donor PTB7-Th as active layer has higher energy conversion efficiency and short circuit current.In addition, the transparent organic solar cell prepared with the active layer obtains higher energy conversion efficiency under the premise of maintaining higher average visible light transmittance.The phenoxazine derivative ultra-narrow band gap acceptor prepared in the application has great application prospect in the field of transparent organic solar cell.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of organic solar cells, and in particular relates to a super-narrow-band-gap electron acceptor with a phenoxazine structure as a core, a preparation method thereof, and the use of the acceptor in an organic solar cell. BACKGROUND

[0002] Organic solar cells (OSCs) have attracted extensive attention in the field of renewable clean energy due to their easy fabrication, flexibility, and lightweight characteristics. It is well known that 51% of the photon energy in the solar spectrum is located in the near-infrared (NIR) region, while the visible and ultraviolet regions account for about 43% and 5%, respectively. Therefore, it is crucial to design and synthesize active layer materials that absorb in the NIR region. In the past decade, the development of a large number of efficient near-infrared electron acceptors has enabled single-junction organic solar cells to achieve power conversion efficiencies (PCEs) exceeding 20% in the laboratory. During this period, some super-narrow-band-gap electron acceptors with optical band gaps less than 1.24 eV have been applied to transparent organic solar cells, tandem organic solar cells, and NIR photodetectors.

[0003] Enhancing the intramolecular charge transfer (ICT) effect is an effective strategy for constructing super-narrow-band-gap electron acceptors. For example, introducing an additional ethylene double bond or a bithiophene π bridge between the fused-ring core and the terminal group (Nat. Commun. 2023, 14, 1236.), or introducing an alkoxy chain in the thiophene π bridge or using terminal groups with stronger electron-withdrawing ability (Joule 2024, 8, 2238-2249.). Such acceptor materials all exhibit excellent device performance and show great potential in the field of transparent organic solar cells. SUMMARY

[0004] The present application aims to provide a super-narrow-band-gap acceptor with a phenoxazine structure as a core, a preparation method thereof, and an organic solar cell comprising the acceptor. The acceptor is synthesized by introducing a halogen atom in the phenoxazine structure and an additional ethylene double bond between the fused-ring core and the electron-withdrawing terminal group, resulting in a new type of organic solar cell acceptor material.

[0005] The technical solutions of the present application are as follows:

[0006] According to one aspect of the present application, one object of the present application is to provide a phenoxazine derivative super-narrow-band-gap acceptor having the structure shown in general formula (I),

[0007]

[0008] wherein R1, R2, R3, and R4 are each independently a branched or straight-chain C1-C30 alkyl group;

[0009] X1, X2, X3, X4, X5and X6, equal to or different from each other, are each independently selected from hydrogen or halogen.

[0010] Preferably, R1, R2, R3and R4are each independently a branched or linear C6-C20alkyl group.

[0011] More preferably, R1, R2, R3and R4are each independently a branched or linear C6-C16alkyl group.

[0012] More preferably, R1and R2, equal to or different from each other, are each independently a branched or linear C8-C12alkyl group.

[0013] More preferably, R3and R4, equal to or different from each other, are each independently a branched C8-C16alkyl group.

[0014] Preferably, X1, X2, X3, X4, X5and X6, equal to or different from each other, are each independently selected from hydrogen, fluorine, chlorine or bromine.

[0015] More preferably, X1, X2, X3, X4, X5and X6, equal to or different from each other, are each independently selected from hydrogen, fluorine or bromine.

[0016] In some embodiments of the present application, the phenoxazine derivative ultra-narrow band gap acceptor of formula I is selected from the following structures:

[0017]

[0018] According to a second aspect of the present application, a second object of the present application is to provide a method for preparing the phenoxazine derivative ultra-narrow band gap acceptor of formula I, which can be carried out according to similar methods in the prior art, for example according to the prior art mentioned in the background section (Nat. Commun. 2023, 14, 1236.).

[0019] According to a third aspect of the present application, a third object of the present application is to provide the use of the phenoxazine derivative ultra-narrow band gap acceptor of formula I in an organic solar cell.

[0020] According to a fourth aspect of the present application, a fourth object of the present application is to provide an active layer for use in an organic solar cell, which is composed of the phenoxazine derivative ultra-narrow band gap acceptor of formula I according to the present application and a polymer donor, the mass ratio of the polymer donor and the phenoxazine derivative ultra-narrow band gap acceptor being 1:5 to 1:0.33, wherein the polymer donor is PTB7-Th, the structural formula of which is as follows:

[0021]

[0022] Preferably, the mass ratio of the polymer donor and the phenoxazine derivative ultra-narrow band gap acceptor is 1:5-1:0.5, more preferably 1:1-1:2, and most preferably 1:1.7.

[0023] According to the fifth aspect of the present application, the fifth object of the present application is to provide 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 comprises the phenoxazine derivative ultra-narrow band gap acceptor represented by the formula I and the polymer donor according to the present application.

[0024] Preferably, the thickness of the active layer is 30-300 nm.

[0025] Preferably, the substrate of the organic solar cell is glass; the anode is ITO; the hole transport layer is poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS); the electron transport layer is PDINN or ZnO; and the cathode is Ag or AgNWs.

[0026] Preferably, for the transparent organic solar cell, ZnO is the electron transport layer and AgNWs is the cathode.

[0027] Advantages

[0028] The phenoxazine derivative ultra-narrow band gap acceptor in the present application has an extremely low thin film optical band gap (-1.2 eV). The organic solar cell prepared by matching it with the narrow band gap polymer donor PTB7-Th as the active layer has a higher energy conversion efficiency and short circuit current. In addition, the transparent organic solar cell prepared with this active layer has a higher energy conversion efficiency while maintaining a relatively high average visible light transmittance. The phenoxazine derivative ultra-narrow band gap acceptor prepared in the present application has great application prospects in the field of transparent organic solar cells. BRIEF DESCRIPTION OF DRAWINGS

[0029] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are some embodiments of the present application, and those skilled in the art can also obtain other drawings according to these drawings without creative labor.

[0030] Figure 1 UV-Vis absorption spectra of PA1, PA2 and PA3 prepared in Examples 1-3 in thin film state.

[0031] Figure 2Current density-voltage (J-V) curves of the organic solar cells prepared based on the PTB7-Th:PA1, PTB7-Th:PA2 and PTB7-Th:PA3 active layers prepared in Examples 5 to 7 were measured under AM 1.5G.

[0032] Figure 3 Current density-voltage (J-V) curves of the transparent organic solar cells prepared based on the PTB7-Th:PA3 active layer prepared in Example 8 were measured under AM 1.5G. DETAILED DESCRIPTION

[0033] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before describing the present disclosure, it should be understood that the terms used in the specification and the appended claims are not to be interpreted as being limited to general and dictionary meanings, but are to be interpreted based on the meanings and concepts of the technical field of the present disclosure on the basis of the principle that the inventor is allowed to define the terms in order to best explain the present disclosure. Therefore, the description herein merely describes preferred embodiments of the present disclosure, but is not intended to limit the scope of the present disclosure, and it should be understood that other equivalents and modifications can be made thereto without departing from the spirit and scope of the present disclosure.

[0034] In the present document, the terms "comprise", "include", "have", "contain", or other similar terms are open-ended transitional phrases that are intended to encompass non-exclusive inclusion. For example, a composition or article that comprises a list of elements is not limited to only those elements recited but can also include other elements not expressly listed or inherent to such composition or article. In addition, unless expressly specified to the contrary, the term "or" refers to an inclusive "or" rather than an exclusive "or". For example, any of the following are satisfied for "A or B": A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and A and B are both true (or present). In addition, in the present document, the terms "comprise", "include", "have", "contain" are interpreted as having been specifically disclosed and encompassing "consist of" and "consist essentially of" closed or semi-closed transitional phrases.

[0035] In this document, all formulations of features or conditions recited in the form of a range or a parameter are for the convenience of the reader only. The description of a range or a parameter is to be read as if it explicitly recited every possible sub-range and individual value within the range, particularly the integers within the range. For example, a range of "1 to 8" is to be read as if it explicitly recited every possible sub-range, particularly the sub-ranges of 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., and every individual value, particularly the integers within the range, such as 1, 2, 3, 4, 5, 6, 7, 8, etc. The foregoing interpretation method applies to all aspects of the present application, regardless of whether the range is broad or narrow, unless otherwise indicated.

[0036] If an amount or other numerical or parameter is expressed in a range, a preferred range or a series of upper and lower limits, it is to be understood that the range specifically disclosed herein includes all ranges formed by any pair of an upper limit or preferred value of the range with a lower limit or preferred value of the range, whether or not the ranges are expressly disclosed. In addition, when a range of values is recited herein, unless otherwise stated, the range is to include the endpoints and all the integers and fractions within the range, unless otherwise indicated.

[0037] In this document, a numerical value is to be understood as having the precision of the number of significant figures of the numerical value, provided that the purpose of the invention can be achieved. For example, the number 40.0 is to be understood as encompassing the range from 39.50 to 40.49.

[0038] In addition, unless otherwise specified, the reagents and solvents disclosed below are purchased from Shanghai Biotech Co., Ltd. 1 H NMR was measured by using Bruker's AV-500 / 600MHz nuclear magnetic resonance spectrometer; ultraviolet-visible absorption spectrum was measured by using Agilent's Cary 6000i; current density-voltage (J-V) curve was measured by using Keithley's 2400 semiconductor characterization system.

[0039] The following examples are only listed as examples of embodiments of the present application, and do not constitute any limitation on the present application, and those skilled in the art can understand that modifications within the scope of the essence and concept of the present application fall within the protection scope of the present application. Unless otherwise specified, the reagents and instruments used in the following examples are commercially available products.

[0040] The synthetic routes of the phenoxazine derivative ultra-narrow band gap acceptors (PA1, PA2 and PA3) prepared in Examples 1-3 are as follows (Compound 1 is purchased from Shenzhen Ruiyun Optoelectronic Material Technology Co., Ltd.):

[0041]

[0042] Example 1: Preparation of PA-1, the structural formula of which is as follows,

[0043]

[0044] Step 1: Synthesis of compound 2a:

[0045] To a solution of 25 mL of compound 1 (300 mg, 0.25 mmol) in tetrahydrofuran was added 1.76 mL of 1 mol / L LiAlH4(1.76 mmol) and the reaction was stirred at 85 °C under N2atmosphere for 10 hours. After cooling to room temperature, 20 mL of water was slowly added to quench the reaction under ice-bath condition. The reaction mixture was then extracted with dichloromethane / water. The organic phase was combined, dried over anhydrous sodium sulfate and the organic solvent was removed under reduced pressure to give the crude product. The crude product was used directly for the next step without further purification.

[0046] To a solution of 45 mL of the crude product in chloroform was added 3,5,6-dichloro-1,4-benzoquinone (DDQ) (170 mg, 0.75 mmol) and o-phenylenediamine (135 mg, 1.25 mmol) sequentially. The reaction was stirred at room temperature under N2atmosphere for 12 hours. After completion of the reaction, 40 mL of water was added to the reaction mixture, which was then extracted with dichloromethane and the solvent was removed under reduced pressure. The crude product was purified by column chromatography on silica gel using n-hexane / dichloromethane (5:1, v / v) as the eluent and red solid 2a (226 mg) was obtained after vacuum drying with a yield of 73%. 1 H NMR (600 MHz, CDC13) δ 8.63 - 8.56 (m, 2H), 7.91 - 7.84 (m, 2H), 7.05 (s, 2H), 4.67 (d, J = 7.8 Hz, 4H), 2.89 (t, J = 7.7 Hz, 4H), 2.21 - 2.13 (m, 2H), 1.95 - 1.89 (m, 4H), 1.54 - 1.47 (m, 4H), 1.46 - 1.40 (m, 4H), 1.38 - 1.23 (m, 26H), 1.18 - 0.85 (m, 52H), 0.80 (t, J = 7.3 Hz, 6H), 0.68 (t, J = 7.2 Hz, 6H).

[0047] Step 2: Synthesis of compound 3a:

[0048] Compound 2a (225 mg, 0.18 mmol) and 0.16 mL of N,N-dimethylformamide (DMF) were dissolved in 10 mL of dichloroethane (DCE). Under ice bath conditions, 0.16 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 5.5 hours. After the reaction was complete, the mixture was cooled to room temperature, and 5 mL of saturated K₂CO₃ solution was added and 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 / dichloromethane (1:1, v / v) as eluent, and dried under vacuum to give a red solid 3a (210 mg), in 89% yield. 1 H NMR (600MHz, CDCl3) δ10.09(s,2H),8.45–8.38(m,2H),7.84–7.78(m,2H),4.61(d,J=7.9Hz,4H),3.18(t,J=7.8Hz,4H),2.09–2.00(m,2H),1. 95–1.85(m,4H),1.47–1.42(m,4H),1.37–1.32(m,4H),1.26–1.18(m,2 6H),1.05–0.79(m,52H),0.70(t,J=7.3Hz,6H),0.59(t,J=7.3Hz,6H).

[0049] Step 3: Synthesis of compound 4a:

[0050] (1,3-Dioxolane-2-yl)methyl)tributylphosphonium bromide (107 mg, 0.29 mmol) was added to 20 mL of a tetrahydrofuran solution of compound 3a (168 mg, 0.13 mmol). Then, NaH (26.2 mg, 0.66 mmol) (60% dispersed in mineral oil) was added, and the reaction mixture was stirred at room temperature for 16 hours under a nitrogen atmosphere. 0.8 mL of 10% HCl was added, and stirring continued for 3 hours at room temperature. 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 / dichloromethane (1:2, v / v) as eluent, and dried under vacuum to give a dark red solid 4a (158 mg), in 90% yield. 1H NMR(600MHz, CDCl3)δ9.71(d,J=7.5Hz,2H),8.50–8.43(m,2H),7.89–7.83(m,2H),7.80 (d,J=15.2Hz,2H),6.54(dd,J=15.2,7.5Hz,2H),4.65(d,J=7.8Hz,4H),3.04(t,J=7.9H z,4H),2.16–2.07(m,2H),1.94–1.86(m,4H),1.54–1.48(m,4H),1.44–1.39(m,4H),1.3 5–1.25(m,26H),1.13–0.86(m,52H),0.77(t,J=7.3Hz,6H),0.66(td,J=7.1,2.0Hz,6H).

[0051] Step 4: Synthesis of PA1:

[0052] Compound 4a (135 mg, 0.1 mmol), 5,6-difluoro-3-(dicyanomethylene)indophenone (81 mg, 0.35 mmol), and 0.5 mL of pyridine were dissolved in 25 mL of chloroform. The reaction mixture was stirred at room temperature for 70 minutes. After the reaction was completed, 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 / dichloromethane (1:1, v / v) as eluent, and dried under vacuum to give a black solid PA1 (135 mg), with a yield of 76%. 1 H NMR (500MHz, CDCl3) δ8.78–8.57(m,2H),8.57–8.48(m,4H),8.48–8.43(m,2H),7.93–7.87(m ,2H),7.76(d,J=13.4Hz,2H),7.67(t,J=7.5Hz,2H),4.69(d,J=7.0Hz,4H),3.08(t,J=7.0Hz, 4H),2.24–2.12(m,2H),1.96–1.86(m,4H),1.54–1.50(m,4H),1.45–1.40(m,4H),1.38–1.22( m,26H),1.17–0.95(m,44H),0.88–0.84(m,8H),0.75(t,J=7.2Hz,6H),0.68(t,J=6.8Hz,6H).

[0053] Example 2: Preparation of PA-2, with the following structural formula,

[0054]

[0055] Step 1: Synthesis of compound 2b:

[0056] 1.76 mL of 1 mol / L LiAlH4 (1.76 mmol) was added to 25 mL of a tetrahydrofuran solution of compound 1 (300 mg, 0.25 mmol). The mixture was heated to 85 °C and stirred for 10 hours under a nitrogen atmosphere. After cooling to room temperature, 20 mL of water was slowly added in an ice bath to quench the reaction. The mixture was then extracted with dichloromethane / water. The combined organic phases were dried over anhydrous sodium sulfate and the organic solvent was removed under reduced pressure to obtain the crude product. The crude product was used directly in the next reaction without further purification.

[0057] 3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) (170 mg, 0.75 mmol) and 4-bromo-o-phenylenediamine (234 mg, 1.25 mmol) were added sequentially to 45 mL of a chloroform solution of the crude product. The reaction mixture was stirred at room temperature under a nitrogen atmosphere for 12 hours. After the reaction was complete, 40 mL of water was added to the reaction mixture, followed by extraction with dichloromethane and removal of the solvent under reduced pressure. The crude product was purified by silica gel column chromatography using n-hexane / dichloromethane (5:1, v / v) as the eluent, and dried under vacuum to give a red solid 2b (262 mg), with a yield of 80%. 1 H NMR (500MHz, CDCl3) δ8.66 (d, J=2.1Hz, 1H), 8.32 (d, J=9.0Hz, 1H), 7.87 (dd, J= 9.0,2.2Hz,1H),7.02(s,2H),4.65(d,J=7.8Hz,4H),2.86(t,J=7.7Hz,4H),2.2 0–2.11(m,2H),1.93–1.85(m,4H),1.51–1.44(m,4H),1.44–1.38(m,4H),1.38– 1.21(m,26H),1.14–0.83(m,52H),0.78(t,J=7.3Hz,6H),0.65(t,J=7.1Hz,6H).

[0058] Step 2: Synthesis of compound 3b:

[0059] Compound 2b (237 mg, 0.18 mmol) and 0.16 mL of N,N-dimethylformamide (DMF) were dissolved in 10 mL of dichloroethane (DCE). Under ice bath conditions, 0.16 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 5.5 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 / dichloromethane (1:1, v / v) as eluent, and dried under vacuum to give a red solid 3b (232 mg) in 94% yield.1 H NMR (600MHz, CDCl3) δ10.09(s,2H),8.59(d,J=2.0Hz,1H),8.25(d,J=8.9Hz,1H ),7.86(dd,J=8.9,2.0Hz,1H),4.60(d,J=7.8Hz,4H),3.17(t,J=7.7Hz,4H),2.0 9–2.00(m,2H),1.94–1.85(m,4H),1.46–1.41(m,4H),1.37–1.32(m,4H),1.23– 1.18(m,26H),1.05–0.79(m,52H),0.70(t,J=7.3Hz,6H),0.59(t,J=7.3Hz,6H).

[0060] Step 3: Synthesis of compound 4b:

[0061] (1,3-Dioxolane-2-yl)methyl)tributylphosphonium bromide (107 mg, 0.29 mmol) was added to 20 mL of a tetrahydrofuran solution of compound 3b (178 mg, 0.13 mmol). Then, NaH (26.2 mg, 0.66 mmol) (60% dispersed in mineral oil) was added, and the reaction mixture was stirred at room temperature for 16 hours under a nitrogen atmosphere. 0.8 mL of 10% HCl was added, and stirring continued for 3 hours at room temperature. 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 / dichloromethane (1:2, v / v) as eluent, and dried under vacuum to give a dark red solid 4b (172 mg), in 93% yield. 1 H NMR (600MHz, CDCl3) δ9.64(d,J=7.5Hz,2H),8.57(d,J=2.0Hz,1H),8.24(d,J=9.0Hz,1H),7.8 4(dd,J=8.9,2.0Hz,1H),7.72(d,J=15.2Hz,2H),6.47(dd,J=15.2,7.6Hz,2H),4.58(d,J=7.8H z,4H),2.96(t,J=7.8Hz,4H),2.11–2.00(m,2H),1.88–1.77(m,4H),1.47–1.41(m,4H),1.38–1 .32(m,4H),1.29–1.17(m,26H),1.08–0.78(m,52H),0.70(t,J=7.3Hz,6H),0.63–0.56(m,6H).

[0062] Step 4: Synthesis of PA2:

[0063] Compound 4b (142 mg, 0.1 mmol), 5,6-difluoro-3-(dicyanomethylene)indophenone (81 mg, 0.35 mmol), and 0.5 mL of pyridine were dissolved in 25 mL of chloroform. The reaction mixture was stirred at room temperature for 70 minutes. After the reaction was completed, 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 / dichloromethane (1:1, v / v) as eluent, and dried under vacuum to give a black solid PA2 (98 mg), with a yield of 56%. 1 H NMR (600MHz, CDCl3) δ8.71–8.58(m,3H),8.57–8.46(m,4H),8.29(d,J=8.9Hz,1H),7.93(dd,J=8 .9,2.0Hz,1H),7.74(d,J=14.2Hz,2H),7.67(t,J=7.4Hz,2H),4.69(d,J=6.8Hz,4H),3.07(t,J=7 .8Hz,4H),2.22–2.14(m,2H),1.94–1.86(m,4H),1.54–1.49(m,4H),1.45–1.39(m,4H),1.37–1. 23(m,26H),1.18–0.96(m,44H),0.88–0.84(m,8H),0.75(t,J=7.3Hz,6H),0.69(t,J=6.9Hz,6H).

[0064] Example 3: Preparation of PA-3, with the following structural formula,

[0065]

[0066] Step 1: Synthesis of compound 2c:

[0067] 1.76 mL of 1 mol / L LiAlH4 (1.76 mmol) was added to 25 mL of a tetrahydrofuran solution of compound 1 (300 mg, 0.25 mmol). The mixture was heated to 85 °C and stirred for 10 hours under a nitrogen atmosphere. After cooling to room temperature, 20 mL of water was slowly added in an ice bath to quench the reaction. The mixture was then extracted with dichloromethane / water. The combined organic phases were dried over anhydrous sodium sulfate and the organic solvent was removed under reduced pressure to obtain the crude product. The crude product was used directly in the next reaction without further purification.

[0068] 3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) (170 mg, 0.75 mmol) and 4,5-dibromo-o-phenylenediamine (333 mg, 1.25 mmol) were added sequentially to 45 mL of a chloroform solution of the crude product. The reaction mixture was stirred at room temperature under a nitrogen atmosphere for 12 hours. After the reaction was complete, 40 mL of water was added to the reaction mixture, followed by extraction with dichloromethane and removal of the solvent under reduced pressure. The crude product was purified by silica gel column chromatography using n-hexane / dichloromethane (5:1, v / v) as the eluent, and dried under vacuum to give a reddish-brown solid 2c (237 mg), with a yield of 68%. 1 H NMR (600MHz, CDCl3) δ8.78(s,2H),7.03(s,2H),4.64(d,J=7.9Hz,4H),2.86(t,J=7.7Hz,4H),2.19–2.09(m,2H),1.93–1.86(m,4 H),1.50–1.45(m,4H),1.43–1.38(m,4H),1.33–1.24(m,26H),1.14–0.86(m,52H),0.78(t,J=7.3Hz,6H),0.65(t,J=7.2Hz,6H).

[0069] Step 2: Synthesis of compound 3c:

[0070] Compound 2c (251 mg, 0.18 mmol) and 0.16 mL of N,N-dimethylformamide (DMF) were dissolved in 10 mL of dichloroethane (DCE). Under ice bath conditions, 0.16 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 5.5 hours. After the reaction was complete, the mixture was cooled to room temperature, and 5 mL of saturated K₂CO₃ solution was added and 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 / dichloromethane (1:1, v / v) as eluent, and dried under vacuum to give a red solid 3c (245 mg) in 94% yield. 1 H NMR (600MHz, CDCl3) δ10.09(s,2H),8.70(s,2H),4.60(d,J=7.9Hz,4H),3.16(t,J=7.8Hz,4H),2.09–2.01(m,2H),1.93–1.85(m, 4H),1.46–1.41(m,4H),1.37–1.31(m,4H),1.28–1.15(m,26H),1.07–0.78(m,52H),0.71(t,J=7.3Hz,6H),0.59(t,J=7.1Hz,6H).

[0071] Step 3: Synthesis of compound 4c:

[0072] (1,3-Dioxolane-2-yl)methyl)tributylphosphonium bromide (107 mg, 0.29 mmol) was added to 20 mL of a tetrahydrofuran solution of compound 3b (189 mg, 0.13 mmol). Then, NaH (26.2 mg, 0.66 mmol) (60% dispersed in mineral oil) was added, and the reaction mixture was stirred at room temperature for 16 hours under a nitrogen atmosphere. 0.8 mL of 10% HCl was added, and stirring continued for 3 hours at room temperature. 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 / dichloromethane (1:2, v / v) as eluent, and dried under vacuum to give a dark red solid 4c (178 mg), in 92% yield. 1 H NMR(600MHz, CDCl3)δ9.72(d,J=7.5Hz,2H),8.76(s,2H),7.79(d,J=15.2Hz,2H), 6.54(dd,J=15.2,7.6Hz,2H),4.65(d,J=7.9Hz,4H),3.02(t,J=7.8Hz,4H),2.17– 2.07(m,2H),1.93–1.84(m,4H),1.53–1.47(m,4H),1.44–1.38(m,4H),1.35–1.24 (m,26H),1.15–0.85(m,52H),0.77(t,J=7.3Hz,6H),0.66(td,J=7.1,1.5Hz,6H).

[0073] Step 4: Synthesis of PA3:

[0074] Compound 4c (148 mg, 0.1 mmol), 5,6-difluoro-3-(dicyanomethylene)indophenone (81 mg, 0.35 mmol), and 0.5 mL of pyridine were dissolved in 25 mL of chloroform. The reaction mixture was stirred at room temperature for 70 minutes. After the reaction was completed, 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 / dichloromethane (1:1, v / v) as eluent, and dried under vacuum to give a black solid PA3 (135 mg), with a yield of 70%. 1H NMR(600MHz, CDCl3)δ8.79(s,2H),8.71–8.61(m,2H),8.58–8.49(m,4H),7.76(d,J=14 .3Hz,2H),7.68(t,J=7.4Hz,2H),4.68(d,J=6.8Hz,4H),3.07(t,J=7.8Hz,4H),2.22–2. 11(m,2H),1.94–1.86(m,4H),1.53–1.49(m,4H),1.45–1.40(m,4H),1.34–1.24(m,26H ),1.16–0.95(m,44H),0.87–0.84(m,8H),0.76(t,J=7.3Hz,6H),0.68(t,J=6.9Hz,6H).

[0075] Example 4: Ultraviolet-visible absorption spectroscopy of the phenolic aziridine derivative ultranarrow bandgap acceptors (PA1, PA2 and PA3) prepared in Examples 1 to 3.

[0076] The receptors prepared in Examples 1-3 were dissolved in chloroform to prepare a solution with a concentration of 10 mg / mL. This solution was then spin-coated onto a quartz plate at 4000 rpm to form a thin film sample, and the absorption of the film was measured using a UV-Vis absorption spectrometer. The absorption spectra of PA1, PA2, and PA3 in the film are shown below. Figure 1 As shown in the figure. The results show that the maximum absorption peak of PA1 is at 887 nm, the absorption onset edge is at 1021 nm, and the optical band gap is 1.21 eV; the maximum absorption peak of PA2 is at 865 nm, the absorption onset edge is at 1019 nm, and the optical band gap is 1.22 eV; the maximum absorption peak of PA3 is at 874 nm, the absorption onset edge is at 1041 nm, and the optical band gap is 1.19 eV.

[0077] Example 5: Fabrication and performance of organic solar cells based on PTB7-Th:PA1 active layer.

[0078] The optoelectronic device structure is ITO / PEDOT:PSS / PTB7-Th:PA1 / PDINN / Ag.

[0079] 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 wafers were then transferred to a glove box under a nitrogen atmosphere. An active layer solution was prepared in the glove box, with a PTB7-Th to PA1 mass ratio of 1:1.7 and a total concentration of 17 mg / mL, and 0.5% (v / v) of 1-chloronaphthalene was added as an additive. This solution was stirred at 50°C for 4 hours, then spin-coated onto the PEDOT:PSS layer at 3000 rpm, followed by annealing at 50°C for 5 minutes. A 1 mg / mL PDINN solution was spin-coated onto the active layer at 3000 rpm. Finally, 100 nm of Ag was deposited on the PDINN layer via thermal vacuum evaporation. The effective area of ​​the device was defined as 0.03 cm by a shadow mask. 2 The fabricated device was named PTB7-Th:PA1.

[0080] 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:PA1 device is 0.701V, and the short-circuit current is 14.9mA / cm. 2 The fill factor is 60.4%, and the energy conversion efficiency is 6.31%.

[0081] Example 6: Fabrication and performance of organic solar cells based on PTB7-Th:PA2 active layer.

[0082] The optoelectronic device structure is ITO / PEDOT:PSS / PTB7-Th:PA2 / PDINN / Ag.

[0083] The specific steps are the same as in Example 5, except that the active layer solution is changed to PTB7-Th:PA2. The fabricated device is named PTB7-Th:PA2.

[0084] 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:PA2 device is 0.691V, and the short-circuit current is 22.1mA / cm. 2 The fill factor is 64.3%, and the energy conversion efficiency is 9.82%.

[0085] Example 7: Fabrication and performance of organic solar cells based on PTB7-Th:PA3 active layer.

[0086] The optoelectronic device structure is ITO / PEDOT:PSS / PTB7-Th:PA3 / PDINN / Ag.

[0087] The specific steps are the same as in Example 5, except that the active layer solution is changed to PTB7-Th:PA3. The fabricated device is named PTB7-Th:PA3.

[0088] 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:PA3 device is 0.672V, and the short-circuit current is 28.5mA / cm. 2 The fill factor is 71.4%, and the energy conversion efficiency is 13.7%.

[0089] Example 8: Fabrication and performance of a transparent organic solar cell based on a PTB7-Th:PA3 active layer.

[0090] The optoelectronic device structure is ITO / PEDOT:PSS / PTB7-Th:PA3 / ZnO / AgNWs.

[0091] The preparation process is 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. An active layer solution was prepared in the glove box, with a PTB7-Th to PA3 mass ratio of 1:1.7 and a total concentration of 12 mg / mL, and 0.1% 1-chloronaphthalene was added as an additive. This solution was stirred at 50°C for 4 hours, then spin-coated onto the PEDOT:PSS layer at 6000 rpm, followed by annealing at 50°C for 5 minutes. 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 rotation speed of 2500 rpm. The effective area of ​​the device was defined as 0.02 cm by a shadow mask. 2 .

[0092] 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 open-circuit voltage of the transparent device fabricated based on the PTB7-Th:PA3 active layer is 0.673V, and the short-circuit current is 11.3mA / cm. 2 The fill factor is 60.4%, and the energy conversion efficiency is 4.60%. The average visible light transmittance is 70.2%, and the light utilization efficiency is 3.23%.

[0093] 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 phenolazine derivative ultranarrow bandgap receptor having the structure shown in formula (I), in, R1, R2, R3 and R4 are each independently a branched or straight-chain C1-C30 alkyl group; X1 and X2 may be the same as or different from each other, and each is independently selected from hydrogen or halogen; X3, X4, X5, and X6 may be the same as or different from each other, and each is an independent halogen.

2. The phenolazine derivative ultranarrow bandgap receptor according to claim 1, characterized in that, R1, R2, R3 and R4 are each independently a branched or straight-chain C6-C20 alkyl group.

3. The phenolazine derivative ultranarrow bandgap receptor according to claim 1, characterized in that, R1, R2, R3 and R4 are each independently a branched or straight-chain C6-C16 alkyl group.

4. The phenolazine derivative ultranarrow bandgap receptor according to claim 1, characterized in that, R1 and R2 may be the same or different, and each is independently a branched or straight-chain C8-C12 alkyl group.

5. The phenolazine derivative ultranarrow bandgap receptor according to claim 1, characterized in that, R3 and R4 may be the same or different, and each is independently a branched C8-C16 alkyl group.

6. The phenolazine derivative ultranarrow bandgap receptor according to claim 1, characterized in that, X1 and X2 may be the same or different, and each is independently selected from hydrogen, fluorine, chlorine or bromine; X3, X4, X5 and X6 may be the same or different from each other, and each is independently selected from fluorine, chlorine or bromine.

7. The phenolazine derivative ultranarrow bandgap receptor according to claim 1, characterized in that, X1 and X2 may be the same or different, and are independently selected from hydrogen, fluorine or bromine; X3, X4, X5 and X6 may be the same or different, and are independently selected from fluorine, chlorine or bromine.

8. The phenolazine derivative ultranarrow bandgap receptor according to claim 1, characterized in that, The phenol-azine derivative ultranarrow bandgap receptor shown in Formula I is selected from the following structures: 。 9. The application of the phenolazine derivative ultranarrow bandgap acceptor according to any one of claims 1 to 8 in organic solar cells.

10. An active layer for use in an organic solar cell, the active layer comprising a phenolic azircon derivative ultranarrow bandgap acceptor and a polymer donor according to any one of claims 1 to 6, wherein the mass ratio of the polymer donor to the phenolic azircon derivative ultranarrow bandgap acceptor is 1:5 to 1:0.33, wherein the polymer donor is PTB7-Th; The mass ratio of the polymer donor to the phenolazine derivative ultranarrow band gap acceptor is 1:5 to 1:0.

5.

11. The active layer according to claim 10, characterized in that, The mass ratio of the polymer donor to the phenolazine derivative ultranarrow bandgap acceptor is 1:1 to 1:

2.

12. The active layer according to claim 10, characterized in that, The mass ratio of the polymer donor to the phenolazine derivative ultranarrow bandgap acceptor is 1:1.

7.

13. 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 comprises a phenolic aziridine derivative ultranarrow bandgap acceptor according to any one of claims 1 to 8.

14. The organic solar cell according to claim 13, characterized in that, The thickness of the active layer is 30~300nm.

15. The organic solar cell according to claim 13, 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) (PEDOT:PSS); the electron transport layer is PDINN or ZnO; and the cathode is Ag or AgNWs.

16. The organic solar cell according to claim 13, characterized in that, For transparent organic solar cells, ZnO is the electron transport layer and AgNWs is the cathode.

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