Phenolazine derivative ultra-narrow band gap receptor, preparation method thereof and application of phenolazine derivative ultra-narrow band gap receptor in organic solar cell

Abstract

The invention discloses an ultra-narrow band gap electron acceptor which is represented by a formula (I) and takes a phenazine structure as a core, a preparation method of the electron acceptor and application of the electron acceptor in an organic solar cell. The phenazine derivative ultra-narrow band gap receptor provided by the invention has an extremely low film optical band gap (-1.2 eV). The organic solar cell prepared by matching with a narrow-band gap polymer donor PTB7-Th as an active layer has high energy conversion efficiency and short-circuit current. In addition, the transparent organic solar cell prepared from the active layer obtains higher energy conversion efficiency on the premise of maintaining higher average visible light transmittance. The phenazine derivative ultra-narrow band gap receptor prepared by the invention has a huge application prospect in the field of transparent organic solar cells. # imgabs0 #

Description

Technical Field

[0001] The present invention belongs to the technical field of organic solar cells, and in particular relates to an ultra-narrow bandgap electron acceptor with a phenolazine structure as a core, a preparation method thereof, and use of the acceptor in an organic solar cell. Background Art

[0002] Organic solar cells (OSCs) have attracted extensive attention in the field of renewable clean energy due to their easy manufacturing, flexibility and light weight. It is well known that 51% of the photon energy in the solar spectrum is in the near-infrared (NIR) region, while the visible and ultraviolet regions account for approximately 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 ultra-narrow bandgap electron acceptors with optical band gaps less than 1.24 eV have been applied to transparent organic solar cells, stacked organic solar cells, and NIR photodetectors.

[0003] Enhancing the intramolecular charge transfer (ICT) effect is an effective strategy to construct ultra-narrow bandgap electron acceptors. For example, introducing additional ethylene double bonds or bithiophene π bridges between the fused ring core and the terminal group (Nat. Commun. 2023, 14, 1236.), or introducing alkoxy chains in the thiophene π bridge or using end 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 of the invention

[0004] The purpose of the present invention is to provide an ultra-narrow bandgap receptor with a phenolazine structure as the core, a preparation method thereof, and an organic solar cell comprising the receptor. The receptor is synthesized into a new type of organic solar cell receptor material by introducing halogen atoms into the phenolazine structure and introducing an additional ethylene double bond between the condensed ring core and the electron-withdrawing end group.

[0005] The technical solution of the present invention is as follows:

[0006] According to one aspect of the present invention, an object of the present invention is to provide a phenolazine derivative ultra-narrow band gap receptor having a structure shown in general formula (I),

[0007]

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

[0009] X1, X2, X3, X4, X5 and X6 are the same as or different from each other and are each independently selected from hydrogen or halogen.

[0010] Preferably, R1, R2, R3 and R4 are each independently a branched or linear C6-C20 alkyl group.

[0011] More preferably, R1, R2, R3 and R4 are each independently a branched or linear C6-C16 alkyl group.

[0012] More preferably, R1 and R2 are the same or different, and are each independently a branched or linear C8-C12 alkyl group.

[0013] More preferably, R3 and R4 are the same or different and are each independently a branched C8-C16 alkyl group.

[0014] Preferably, X1, X2, X3, X4, X5 and X6 are the same or different and are independently selected from hydrogen, fluorine, chlorine or bromine.

[0015] More preferably, X1, X2, X3, X4, X5 and X6 are the same or different and are independently selected from hydrogen, fluorine or bromine.

[0016] In some embodiments of the present invention, the ultra-narrow band gap receptor of the phenolazine derivative represented by Formula I is selected from the following structures:

[0017]

[0018] According to the second aspect of the present invention, the second object of the present invention is to provide a method for preparing an ultra-narrow band gap receptor of a phenolazine derivative shown in Formula I, which can be carried out according to a similar method in the prior art, for example, according to the prior art mentioned in the background technology section (Nat. Commun. 2023, 14, 1236.).

[0019] According to the third aspect of the present invention, the third object of the present invention is to provide an application of an ultra-narrow bandgap acceptor of a phenolazine derivative as shown in Formula I in an organic solar cell.

[0020] According to the fourth aspect of the present invention, the fourth object of the present invention is to provide an active layer for an organic solar cell, wherein the active layer is composed of an ultra-narrow bandgap acceptor of a phenolazine derivative represented by Formula I according to the present invention and a polymer donor, wherein the mass ratio of the polymer donor to the ultra-narrow bandgap acceptor of the phenolazine derivative is 1:5 to 1:0.33, wherein the polymer donor is PTB7-Th, and its structural formula is,

[0021]

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

[0023] According to the fifth aspect of the present invention, the fifth object of the present invention is to provide an organic solar cell, which comprises a substrate, an anode, a hole transport layer, an active layer, an electron transport layer and a cathode, wherein the active layer comprises the ultra-narrow band gap acceptor of the phenolazine derivative shown in Formula I according to the present invention and the polymer donor.

[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(styrene sulfonate) (PEDOT:PSS); the electron transport layer is PDINN or ZnO; and the cathode is Ag or AgNWs.

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

[0027] Beneficial Effects

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

[0029] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

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

[0031] Figure 2The current density-voltage (JV) 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 measured at AM 1.5G.

[0032] Figure 3 This is the current density-voltage (JV) curve of the transparent organic solar cell based on the PTB7-Th:PA3 active layer prepared in Example 8 measured under AM1.5G. DETAILED DESCRIPTION

[0033] Hereinafter, the preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be interpreted as limited to the general and dictionary meanings, but should be interpreted based on the principle of allowing the inventor to appropriately define the terms for the best interpretation, based on the meaning and concept corresponding to the technical level of the present invention. Therefore, the description herein is only a preferred example for illustrative purposes, and is not intended to limit the scope of the present invention, so it should be understood that other equivalent implementations and modifications can be made without departing from the spirit and scope of the present invention.

[0034] In this document, the terms "include", "including", "have", "contain" or any other similar terms are open conjunctions, which are intended to cover non-exclusive inclusions. For example, a composition or product containing multiple elements is not limited to the elements listed herein, but may also include other elements that are not explicitly listed but are generally inherent to the composition or product. In addition, unless otherwise explicitly stated, the term "or" refers to an inclusive "or" rather than an exclusive "or". For example, any of the following situations satisfies the condition "A or B": 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), and A and B are both true (or exist). In addition, in this document, the interpretation of the terms "include", "including", "have", and "contain" should be considered to have been specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as "consisting of" and "consisting essentially of".

[0035] In this article, all features or conditions defined in the form of numerical ranges or percentage ranges are only for brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be deemed to have covered and specifically disclosed all possible secondary ranges and individual values ​​within the range, especially integer values. For example, the range description of "1 to 8" should be deemed to have specifically disclosed all secondary ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., especially secondary ranges defined by all integer values, and should be deemed to have specifically disclosed individual values ​​such as 1, 2, 3, 4, 5, 6, 7, 8, etc. within the range. Unless otherwise specified, the above interpretation method applies to all contents of the entire present invention, regardless of whether the range is broad or not.

[0036] If the 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 all ranges consisting of any upper limit or preferred value of the range and the lower limit or preferred value of the range have been specifically disclosed herein, regardless of whether these ranges are disclosed separately. In addition, if a numerical range is mentioned herein, unless otherwise specified, the range should include its endpoints and all integers and fractions within the range.

[0037] In this document, under the premise of achieving the purpose of the invention, numerical values ​​should be understood to have the accuracy of the number of significant digits of the numerical value. For example, the number 40.0 should be understood to cover the range from 39.50 to 40.49.

[0038] In addition, unless otherwise specified, the reagents and solvents disclosed below were purchased from Shanghai BiDe Pharmaceutical Technology Co., Ltd. 1 H NMR was measured by using Bruker's AV-500 / 600 MHz nuclear magnetic resonance spectrometer; UV-visible absorption spectra were measured by using Agilent's Cary 6000i; and current density-voltage (JV) curves were measured by using Keithley's 2400 Semiconductor Characterization System.

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

[0040] The synthetic routes of the phenolazine derivative ultra-narrow bandgap receptors (PA1, PA2 and PA3) prepared in Examples 1 to 3 are as follows (Compound 1 was purchased from Shenzhen Ruixun Optoelectronic Materials Technology Co., Ltd.):

[0041]

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

[0043]

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

[0045] 1.76mL 1mol / L LiAlH4 (1.76mmol) was added to a tetrahydrofuran solution of 25mL compound 1 (300mg, 0.25mmol), and the mixture was heated to 85°C and stirred for 10 hours under N2 atmosphere. After cooling to room temperature, 20mL water was slowly added under ice bath conditions to quench the reaction. It was then extracted with dichloromethane / water. The organic phases were combined and dried over anhydrous sodium sulfate and the organic solvent was removed under reduced pressure to obtain a crude product. The crude product was directly used in the next step without further purification.

[0046] 3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) (170 mg, 0.75 mmol) and o-phenylenediamine (135 mg, 1.25 mmol) were added to 45 mL of a chloroform solution of the crude product. The reaction solution was stirred at room temperature for 12 hours under a N2 atmosphere. After the reaction was completed, 40 mL of water was added to the reaction solution, which was then extracted with dichloromethane and the solvent was removed under reduced pressure. The crude product was separated and purified by silica gel column chromatography using n-hexane / dichloromethane (5:1, v / v) as the eluent, and a red solid 2a (226 mg) was obtained after vacuum drying with a yield of 73%. 1 H NMR (600MHz, CDCl3) δ8.63–8.56(m,2H),7.91–7.84(m,2H),7.05(s,2H),4.67(d,J=7.8Hz,4H),2.89(t,J=7.7Hz,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,2 6H),1.18–0.85(m,52H),0.80(t,J=7.3Hz,6H),0.68(t,J=7.2Hz,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 stirred at this temperature for 40 minutes. The temperature was then raised to 85 °C and stirred for 5.5 hours. After the reaction was completed, it was cooled to room temperature, 5 mL of saturated K2CO3 solution was added and stirred for 3 hours. Extracted with dichloromethane and the solvent was removed under reduced pressure. The crude product was separated and purified by silica gel column chromatography with n-hexane / dichloromethane (1:1, v / v) as the eluent, and a red solid 3a (210 mg) was obtained after vacuum drying with a yield of 89%. 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-dioxolan-2-yl)methyl)tributylphosphonium bromide (107 mg, 0.29 mmol) was added to a 20 mL tetrahydrofuran solution of compound 3a (168 mg, 0.13 mmol). NaH (26.2 mg, 0.66 mmol) (60% dispersion in mineral oil) was then added, and the reaction solution was stirred at room temperature for 16 hours under N2 atmosphere. 0.8 mL 10% HCl was added and stirring was continued at room temperature for 3 hours. Extraction was performed with dichloromethane and the solvent was removed under reduced pressure. The crude product was separated and purified by silica gel column chromatography using n-hexane / dichloromethane (1:2, v / v) as eluent, and a dark red solid 4a (158 mg) was obtained after vacuum drying with a yield of 90%. 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-(dicyanomethylidene)indone (81 mg, 0.35 mmol) and 0.5 mL of pyridine were dissolved in 25 mL of chloroform. The reaction solution was stirred at room temperature for 70 minutes. After the reaction was completed, it was extracted with dichloromethane and the solvent was removed under reduced pressure. The crude product was separated and purified by silica gel column chromatography using n-hexane / dichloromethane (1:1, v / v) as the eluent, and vacuum dried to obtain 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, the structural formula is as follows,

[0054]

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

[0056] 1.76mL 1mol / L LiAlH4 (1.76mmol) was added to a tetrahydrofuran solution of 25mL compound 1 (300mg, 0.25mmol), and the mixture was heated to 85°C and stirred for 10 hours under N2 atmosphere. After cooling to room temperature, 20mL water was slowly added under ice bath conditions to quench the reaction. It was then extracted with dichloromethane / water. The organic phases were combined and dried over anhydrous sodium sulfate and the organic solvent was removed under reduced pressure to obtain a crude product. The crude product was directly used in the next step 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 to 45 mL of a chloroform solution of the crude product. The reaction solution was stirred at room temperature for 12 hours under a N2 atmosphere. After the reaction was completed, 40 mL of water was added to the reaction solution, which was then extracted with dichloromethane and the solvent was removed under reduced pressure. The crude product was separated and purified by silica gel column chromatography using n-hexane / dichloromethane (5:1, v / v) as the eluent, and a red solid 2b (262 mg) was obtained after vacuum drying 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 stirred at this temperature for 40 minutes. The temperature was then raised to 85 °C and stirred for 5.5 hours. After the reaction was completed, it was cooled to room temperature, 5 mL of saturated K2CO3 solution was added and stirred for 3 hours. It was extracted with dichloromethane and the solvent was removed under reduced pressure. The crude product was separated and purified by silica gel column chromatography with n-hexane / dichloromethane (1:1, v / v) as the eluent, and a red solid 3b (232 mg) was obtained after vacuum drying with a yield of 94%.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 a 20 mL tetrahydrofuran solution of compound 3b (178 mg, 0.13 mmol). NaH (26.2 mg, 0.66 mmol) (60% dispersion in mineral oil) was then added, and the reaction solution was stirred at room temperature for 16 hours under N2 atmosphere. 0.8 mL 10% HCl was added and stirring was continued at room temperature for 3 hours. Extraction was performed with dichloromethane and the solvent was removed under reduced pressure. The crude product was separated and purified by silica gel column chromatography using n-hexane / dichloromethane (1:2, v / v) as eluent, and a dark red solid 4b (172 mg) was obtained after vacuum drying with a yield of 93%. 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-(dicyanomethylidene)indone (81 mg, 0.35 mmol) and 0.5 mL of pyridine were dissolved in 25 mL of chloroform. The reaction solution was stirred at room temperature for 70 minutes. After the reaction was completed, it was extracted with dichloromethane and the solvent was removed under reduced pressure. The crude product was separated and purified by silica gel column chromatography using n-hexane / dichloromethane (1:1, v / v) as the eluent, and vacuum dried to obtain 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, the structural formula is as follows,

[0065]

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

[0067] 1.76mL 1mol / L LiAlH4 (1.76mmol) was added to 25mL tetrahydrofuran solution of compound 1 (300mg, 0.25mmol), and the mixture was heated to 85°C and stirred for 10 hours under N2 atmosphere. After cooling to room temperature, 20mL water was slowly added under ice bath to quench the reaction. It was then extracted with dichloromethane / water. After combining the organic phases, the organic solvent was removed under reduced pressure and dried over anhydrous sodium sulfate to obtain a crude product. The crude product was directly used in the next step 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 to 45 mL of a chloroform solution of the crude product. The reaction solution was stirred at room temperature for 12 hours under a N2 atmosphere. After the reaction was completed, 40 mL of water was added to the reaction solution, which was then extracted with dichloromethane and the solvent was removed under reduced pressure. The crude product was separated and purified by silica gel column chromatography using n-hexane / dichloromethane (5:1, v / v) as the eluent, and a reddish-brown solid 2c (237 mg) was obtained after vacuum drying 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). 0.16 mL of POCl3 was added under ice bath conditions and stirred at this temperature for 40 minutes. The temperature was then raised to 85 °C and stirred for 5.5 hours. After the reaction was completed, it was cooled to room temperature, 5 mL of saturated K2CO3 solution was added and stirred for 3 hours. It was extracted with dichloromethane and the solvent was removed under reduced pressure. The crude product was separated and purified by silica gel column chromatography using n-hexane / dichloromethane (1:1, v / v) as the eluent, and a red solid 3c (245 mg) was obtained after vacuum drying with a yield of 94%. 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-dioxolan-2-yl)methyl)tributylphosphonium bromide (107 mg, 0.29 mmol) was added to a 20 mL tetrahydrofuran solution of compound 3b (189 mg, 0.13 mmol). NaH (26.2 mg, 0.66 mmol) (60% dispersion in mineral oil) was then added, and the reaction solution was stirred at room temperature for 16 hours under N2 atmosphere. 0.8 mL 10% HCl was added and stirring was continued at room temperature for 3 hours. Extraction was performed with dichloromethane and the solvent was removed under reduced pressure. The crude product was separated and purified by silica gel column chromatography using n-hexane / dichloromethane (1:2, v / v) as eluent, and a dark red solid 4c (178 mg) was obtained after vacuum drying with a yield of 92%. 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-(dicyanomethylidene)indone (81 mg, 0.35 mmol) and 0.5 mL of pyridine were dissolved in 25 mL of chloroform. The reaction solution was stirred at room temperature for 70 minutes. After the reaction was completed, it was extracted with dichloromethane and the solvent was removed under reduced pressure. The crude product was separated and purified by silica gel column chromatography using n-hexane / dichloromethane (1:1, v / v) as the eluent, and a black solid PA3 (135 mg) was obtained after vacuum drying 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: UV-visible absorption spectrum test of the ultra-narrow bandgap receptors (PA1, PA2 and PA3) of phenolazine derivatives prepared in Examples 1 to 3.

[0076] The receptors prepared in Examples 1 to 3 were dissolved in chloroform to prepare a solution with a concentration of 10 mg / mL. The solution was then spin-coated on a quartz plate at a speed of 4000 rpm to prepare a thin film sample, and the film absorption was measured using a UV-visible absorption spectrometer. The absorption spectra of PA1, PA2 and PA3 in the film are shown in Figure 2. Figure 1 The results show that the maximum absorption peak of PA1 is at 887nm, the absorption onset edge is 1021nm, and the optical band gap is 1.21eV; the maximum absorption peak of PA2 is at 865nm, the absorption onset edge is 1019nm, and the optical band gap is 1.22eV; the maximum absorption peak of PA3 is at 874nm, the absorption onset edge is 1041nm, and the optical band gap is 1.19eV.

[0077] Example 5: Preparation 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 is as follows: the strip ITO (indium tin oxide) glass with etching is placed in a cleaning agent, deionized water and ethanol for ultrasonic cleaning, and then purged with nitrogen for drying and plasma treated for 2 minutes. PEDOT:PSS (diluted with deionized water to a mass percentage concentration of 50%) is spin-coated on the ITO substrate at a speed of 4000 rpm and annealed at 150°C for 2 minutes. The wafer is then transferred to a glove box with a nitrogen atmosphere. The active layer solution is prepared in the glove box, the mass ratio of PTB7-Th and PA1 is 1:1.7, the total concentration is 17 mg / mL, and 1-chloronaphthalene with a volume fraction of 0.5% is added as an additive. The solution is stirred at 50°C for 4 hours, then spin-coated on the PEDOT:PSS layer at a speed of 3000 rpm, and then annealed at 50°C for 5 minutes. A PDINN solution with a concentration of 1 mg / mL is spin-coated on the active layer at a speed of 3000 rpm. Finally, 100 nm of Ag was deposited on the PDINN layer by thermal vacuum evaporation. The active area of ​​the device was defined by a shadow mask with an area of ​​0.03 cm 2 The prepared device was named PTB7-Th:PA1.

[0080] In simulated sunlight (AM 1.5G, 100mW / cm 2 ) under irradiation. Figure 2 As shown in Figure 2, the open circuit voltage of the PTB7-Th:PA1 device is 0.701 V and the short circuit current is 14.9 mA / cm 2 , the filling factor is 60.4% and the energy conversion efficiency is 6.31%.

[0081] Example 6: Preparation 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 those in Example 5, except that the active layer solution is changed to PTB7-Th:PA2. The prepared device is named PTB7-Th:PA2.

[0084] In simulated sunlight (AM 1.5G, 100mW / cm 2 ) under irradiation. Figure 2 As shown in Figure 2, the open circuit voltage of the PTB7-Th:PA2 device is 0.691 V and the short circuit current is 22.1 mA / cm 2 , the filling factor is 64.3% and the energy conversion efficiency is 9.82%.

[0085] Example 7: Preparation 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 those in Example 5, except that the active layer solution is changed to PTB7-Th:PA3. The prepared device is named PTB7-Th:PA3.

[0088] In simulated sunlight (AM 1.5G, 100mW / cm 2 ) under irradiation. Figure 2 As shown in Figure 2, the open circuit voltage of the PTB7-Th:PA3 device is 0.672 V and the short circuit current is 28.5 mA / cm 2 , the filling factor is 71.4% and the energy conversion efficiency is 13.7%.

[0089] Example 8: Preparation and performance of transparent organic solar cells based on 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: the etched ITO (indium tin oxide) glass is placed in a cleaning agent, deionized water and ethanol for ultrasonic cleaning, and then purged with nitrogen for drying and then plasma treated for 2 minutes. PEDOT:PSS (diluted with deionized water to a mass percentage concentration of 50%) is spin-coated on the ITO substrate at a speed of 4000 rpm and annealed at 150°C for 2 minutes. The wafer is then transferred to a glove box in a nitrogen atmosphere. The active layer solution is prepared in the glove box, with a mass ratio of PTB7-Th and PA3 of 1:1.7 and a total concentration of 12 mg / mL. At the same time, 1-chloronaphthalene with a volume fraction of 0.1% is added as an additive. The solution is stirred at 50°C for 4 hours, then spin-coated on the PEDOT:PSS layer at a speed of 6000 rpm, and then annealed at 50°C for 5 minutes. The wafer is transferred to the air again, and 3 to 4 layers of ZnO (10 mg / mL) are spin-coated on the active layer at a speed of 4000 rpm. Finally, AgNWs were deposited on the ZnO layer at a spin speed of 2500 rpm. The active area of ​​the device was defined by a shadow mask with a size of 0.02 cm 2 .

[0092] In simulated sunlight (AM 1.5G, 100mW / cm 2 ) under irradiation. Figure 3 As shown in Figure 2, the open circuit voltage of the transparent device prepared based on the PTB7-Th:PA3 active layer is 0.673 V and the short circuit current is 11.3 mA / cm 2 , the filling factor is 60.4%, 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 is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A phenolazine derivative ultra-narrow bandgap receptor having a structure shown in formula (I), in, R1, R2, R3 and R4 are each independently a branched or linear C1-C30 alkyl group; X1, X2, X3, X4, X5 and X6 are the same as or different from each other and are each independently selected from hydrogen or halogen.

2. The phenolazine derivative ultra-narrow band gap receptor according to claim 1, characterized in that: R1, R2, R3 and R4 are each independently a branched or linear C6-C20 alkyl group; More preferably, R1, R2, R3 and R4 are each independently a branched or linear C6-C16 alkyl group.

3. The phenolazine derivative ultra-narrow band gap receptor according to claim 1, characterized in that: R1 and R2 are the same or different, and are each independently a branched or linear C8-C12 alkyl group.

4. The phenolazine derivative ultra-narrow band gap receptor according to claim 1, characterized in that: R3 and R4 are the same or different and are each independently a branched C8-C16 alkyl group.

5. The phenolazine derivative ultra-narrow band gap receptor according to claim 1, characterized in that: X1, X2, X3, X4, X5 and X6 are the same or different and are independently selected from hydrogen, fluorine, chlorine or bromine; More preferably, X1, X2, X3, X4, X5 and X6 are the same or different and are independently selected from hydrogen, fluorine or bromine.

6. The phenolazine derivative ultra-narrow band gap receptor according to claim 1, characterized in that: The phenolazine derivative ultra-narrow bandgap receptor shown in Formula I is selected from the following structures:

7. Use of the phenolazine derivative ultra-narrow bandgap acceptor according to any one of claims 1 to 6 in an organic solar cell.

8. An active layer for an organic solar cell, the active layer comprising the ultra-narrow bandgap acceptor of a phenolazine derivative according to any one of claims 1 to 6 and a polymer donor, the mass ratio of the polymer donor to the ultra-narrow bandgap acceptor of a phenolazine derivative being 1:5 to 1:0.33, wherein the polymer donor is PTB7-Th; Preferably, the mass ratio of the polymer donor to the phenolazine derivative ultra-narrow band gap acceptor is 1:5 to 1:0.5, more preferably 1:1 to 1:2, and most preferably 1:1.

7.

9. 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 phenolazine derivative ultra-narrow bandgap acceptor according to any one of claims 1 to 6 and the polymer donor.

10. The organic solar cell according to claim 9, characterized in that The thickness of the active layer is 30 to 300 nm; 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; the cathode is Ag or AgNWs; Preferably, for transparent organic solar cells, ZnO is the electron transport layer and AgNWs is the cathode.

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