Nine-fused ring conjugated small molecule receptor with S configuration, preparation method thereof and application of nine-fused ring conjugated small molecule receptor in organic photoelectric device

Abstract

The invention relates to a 9-fused ring conjugated small molecule receptor with S configuration, a preparation method thereof and application of the 9-fused ring conjugated small molecule receptor in an organic photoelectric device. The general formula of the molecular structure is as shown in formula 1, R1, R2, R3 and R4 represent different substituted alkyl or aryl substituted units, and A represents an electron withdrawing unit. The structure is beneficial to prolonging the conjugated skeleton and enhancing the intramolecular charge transfer effect, and the unique S configuration also improves the accumulation behavior and crystallinity of molecules. Benefited from the characteristics, when the acceptor material is matched with a proper donor, ideal donor and acceptor miscibility, excellent active layer morphology and remarkably improved energy conversion efficiency can be realized. In addition, when the acceptor material is applied to a semitransparent organic solar cell, a laminated organic solar cell and a near-infrared organic photoelectric detector, the acceptor material also shows excellent device performance.

Description

Technical Field

[0001] The present invention relates to the field of organic optoelectronics, and particularly to an S-type nine-fused-ring small molecule acceptor based on dithieno[3,2-b:2’,3’-d]pyrrole and its applications in organic solar cells, tandem organic solar cells, semi-transparent organic solar cells and near-infrared organic optoelectronic detectors. Background Art

[0002] Energy is the foundation for the survival and development of humanity, and the issue of energy reserves has become an essential and indispensable part of the planning of countries and regions. Research shows that the energy released by just four days of sunlight irradiation exceeds the total amount of fossil energy accumulated on Earth over four billion years. Therefore, the conversion and efficient utilization of photovoltaic energy have become a key solution to the energy crisis.

[0003] Organic solar cells (OSCs) are a new type of solar cell developed in the 1990s, which use organic semiconductors as active materials for photoelectric conversion. Compared with inorganic solar cells, OSCs have significant advantages such as low cost, thin-film, light weight, simple manufacturing process, and can be made into large-area flexible devices, etc. They have broad development and application prospects and have become one of the most dynamic and innovative research frontiers in the fields of new materials and new energy today. Currently, the efficiency of organic solar cells has been increased from less than 10% in the early stage to more than 18% today. This progress is mainly due to the development of new materials and device structures. At the material level, the introduction of non-fullerene acceptor materials has significantly broadened the light absorption spectrum and reduced the voltage loss, becoming the core factor driving the efficiency improvement. In addition, the development of new donor materials (such as D-A-D structure materials) has further optimized the photoelectric conversion performance. In terms of device structure, the exploration from traditional single-layer structures to double-stack or even triple-stack structures has significantly improved the light absorption and charge transport efficiency. At the same time, the development of interface modification materials has also reduced the energy loss at the interface and further improved the device performance.

[0004] For currently mainstream bulk heterojunction organic solar cells, the key structure determining device performance is its active layer. To achieve efficient exciton dissociation, the active layer of OSCs is usually composed of a blend of an electron donor and an electron acceptor. Among them, due to the advantages of non-fullerene acceptors (NFAs) in flexible adjustment of chemical structure and light absorption range, they have received extensive attention from researchers. Especially in recent years, the emergence and development of star non-fullerene acceptors ITIC and Y6 have helped the power conversion efficiency (PCE) of OSCs to exceed 19% with their absorption extended to the near-infrared region (Adv. Mater, 2021, 33, e2102420; Joule, 2022, 6, 171; Angew. Chem. Int. Ed. 2023, 62, e2023126). However, one of the main problems faced by Y-series acceptor materials in organic solar cells is the poor miscibility between the donor and acceptor materials, which not only affects the morphology of the active layer but also directly relates to the photoelectric conversion efficiency of the battery. Among many influencing factors, the molecular structure directly determines its optoelectronic properties, film morphology, and charge transport behavior, thereby affecting the efficiency, stability, and applicability of the device. Adjusting the molecular configuration is one of the powerful means to regulate the molecular structure. The molecular configurations of the donor and acceptor materials determine the phase separation scale in the mixed film. Intermolecular interactions (such as π-π stacking, dipole interactions) will affect the degree of phase separation. The optimal phase separation scale (usually between 10–50 nm) can balance charge transport and charge recombination, thereby improving device performance. At the same time, by adjusting the molecular configuration, various properties of the material (such as visible light transparency, near-infrared absorption, etc.) can be achieved, so as to meet the requirements of different application scenarios (Adv. Mater, 2019, 21, e2018068; Science, 2017, 11, 213; Chinese Chemical Letters, 2023, 34, 10).

[0005] By optimizing the molecular structure, effective regulation of light absorption performance, charge transport characteristics, film morphology, and device stability can be achieved. Future research directions will focus on designing novel molecular configurations, exploring efficient charge separation mechanisms, and developing highly stable materials to promote the further development and commercial application of organic solar cells. Therefore, how to improve molecular packing and crystallinity through molecular design and improve the donor-acceptor miscibility is of great significance. Summary of the Invention

[0006] At present, most high-performance non-fullerene small molecule acceptor materials are based on the Y-series small molecule acceptors represented by Y6, and these materials usually have a molecular structure of A-DA’D-A. For such a molecular structure, expanding the conjugation length, selecting stronger electron-withdrawing and electron-donating units to enhance the intramolecular charge transfer (ICT) effect is an effective way to achieve redshift of absorption. At the same time, by adjusting the ring-closing site to transform the molecule from the W configuration to the S configuration, the molecular packing and the donor-acceptor miscibility can be improved, thereby enhancing the charge transport performance of the device.

[0007] Due to the lone pair electrons on the N atom in the pyrrole ring, the dithieno[3,2-b:2’,3’-d]pyrrole (DTP) unit exhibits strong electron-donating ability. At the same time, the DTP unit itself has good planarity, which helps to enhance the planar structure of the entire molecular skeleton. Therefore, introducing this unit into the S-type nonacene-fused ring small molecule acceptor material can effectively enhance the ICT effect, reduce the band gap, and thus increase the short-circuit current density. At the same time, the absorption spectrum of the material undergoes a redshift and extends to the near-infrared region, resulting in a significant reduction in its absorption in the visible light region. In addition, the introduction of the DTP unit also increases the number of fused rings in the molecule, which helps to extend the conjugated backbone of the molecule and improve its crystallinity, thereby effectively reducing the density of defect states and the energy disorder of the molecule, and ultimately achieving the purpose of suppressing the dark current.

[0008] Therefore, based on the Y-series high-performance acceptors, the present invention uses the DTP unit as the electron-donating unit. In order to further improve the molecular packing and crystallinity, by adjusting the ring-closing site, the W-configuration nonacene-fused ring small molecule acceptor is transformed into the S configuration, and a series of S-configuration nonacene-fused conjugated small molecule acceptors are further designed and synthesized, and their structural formulas are shown in Formula 1.

[0009]

[0010] Among them, represents different substituted benzene electron-donating units; A represents an electron-withdrawing unit; R1, R2, R3, and R4 are each independently selected from H, halogen, a straight-chain or branched-chain alkyl group, ester group, alkoxy group, alkylthio group, or alkylsilyl group having 1 to 50 carbon atoms, and the halogen is F, Cl, Br, or I;

[0011] Further, the electron-withdrawing unit A is selected from the following structures:

[0012]

[0013] Among them, R 5-16 are each independently selected from H, halogen, a straight-chain or branched-chain alkyl group, ester group, alkoxy group, alkylthio group, or alkylsilyl group having 1 to 50 carbon atoms, and the halogen is F, Cl, Br, or I;

[0014] Another object of the present invention is to disclose a preparation method of the above-mentioned S-configured nine-fused-ring conjugated small molecule acceptor based on dithieno[3,2-b:2’,3’-d]pyrrole, comprising the following steps:

[0015] 1) Reacting a p-substituted benzene compound B with a stannylated dithieno[3,2-b:2’,3’-d]pyrrole compound C through a Stille coupling reaction to obtain a compound D;

[0016]

[0017] 2) Subjecting the compound D to Cadogan cyclization to obtain a compound E;

[0018]

[0019] 3) Performing a nucleophilic substitution reaction on the compound E with a haloalkane to obtain a compound F;

[0020]

[0021] Wherein, the selected haloalkane is R2X, and X is any one of bromine and iodine;

[0022] 4) Subjecting the compound F to a Vilsmeier-Haack reaction to obtain a compound G;

[0023]

[0024] 5) Reacting the compound G with a terminal group A through a Knoevenagel reaction to obtain an S-type nine-fused-ring near-infrared small molecule acceptor.

[0025] The terminal group A is any one of the following structures:

[0026]

[0027] Wherein, R 5-16 are each independently selected from H, halogen, a straight-chain or branched-chain alkyl group, ester group, alkoxy group, alkylthio group, or alkylsilyl group having 1 to 50 carbon atoms, and the halogen is F, Cl, Br, or I;

[0028] Another object of the present invention is to disclose a synthesis method of the above-mentioned nine-fused-ring dithieno[3,2-b:2’,3’-d]pyrrole near-infrared small molecule acceptor material, comprising the following specific steps:

[0029] 1) Compound D is obtained by the Stille coupling reaction of substituted benzene compound B and stannylated dithieno[3,2-b:2’,3’-d]pyrrole compound C: The solvent is o-xylene, the catalyst is tris(dibenzylideneacetone)dipalladium, and the ligand is tris(o-tolyl)phosphine. The addition amount of the catalyst is 3%-10% of the total molar amount of the substrates, and the addition amount of the ligand is 10%-20% of the total molar amount of the substrates; the molar ratio of compound B to stannylated dithieno[3,2-b:2’,3’-d]pyrrole compound C is 1:2.5 - 1:3.5; the reaction is refluxed at 100 - 120 °C for 24 - 48 hours;

[0030]

[0031] 2) Compound D, triphenylphosphine, and o-dichlorobenzene undergo a Cadogan cyclization reaction under nitrogen protection, and then a substitution reaction with haloalkanes to obtain compound E. Cadogan cyclization reaction: Through ultraviolet light irradiation, the solvent is o-dichlorobenzene, and the molar amount of triphenylphosphine to compound D is 10:1; the reaction is refluxed at 120 - 160 °C for 10 - 24 hours; Nucleophilic substitution reaction: Using DMF as the solvent and sodium hydroxide as the base, the molar ratio of sodium hydroxide to compound E is 10:1, and the molar ratio of haloalkane to compound E is 6:1 - 8:1. The reaction is refluxed at 80 - 100 °C for 5 - 24 hours;

[0032]

[0033] 3) Compound G is obtained from compound F through the Vilsmeier-Haack reaction. The solvent is 1,2-dichloroethane, and the molar ratio of compound F to phosphorus oxychloride and DMF is 1:15:15 - 1:20:20; the reaction is refluxed at 80 - 90 °C for 8 - 12 hours; then saturated sodium bicarbonate aqueous solution is added and the reaction continues to reflux at 80 - 90 °C for 2 - 3 hours;

[0034]

[0035] 4) Compound G and terminal group A undergo a Knoevenagel reaction to obtain the compound with the structure shown in Formula 1. The solvent is chloroform, pyridine is used as the base source, and the molar ratio of compound G to terminal group A is 1:3.5 - 1:4.5; the reaction is refluxed at 60 - 70 °C for 5 - 12 hours.

[0036]

[0037] The terminal group A is any one of the following structures:

[0038]

[0039] Among them, R 5-16 are each independently selected from H, halogen, a linear or branched alkyl group having 1 to 50 carbon atoms, an ester group, an alkoxy group, an alkylthio group, or an alkylsilyl group, and the halogen is F, Cl, Br, or I;

[0040] Another object of the present invention is to disclose the application of the above-mentioned S-configuration nonacene-fused ring conjugated small molecule acceptor based on dithieno[3,2-b:2’,3’-d]pyrrole in organic solar cells, tandem organic solar cells, near-infrared organic photodetectors, and semi-transparent organic solar cells.

[0041] Furthermore, the S-configuration nonacene-fused ring conjugated small molecule acceptor based on dithieno[3,2-b:2’,3’-d]pyrrole in organic solar cells, tandem organic solar cells, near-infrared organic photodetectors, and semi-transparent organic solar cells includes an active layer, and the active layer contains an S-configuration nonacene-fused ring conjugated small molecule acceptor material based on dithieno[3,2-b:2’,3’-d]pyrrole.

[0042] Furthermore, the organic compound layer further includes a hole transport layer and an electron transport layer. Additional layers, components, or substrates in the organic solar cells, tandem organic solar cells, semi-transparent organic solar cells, and near-infrared organic photodetectors may or may not be present.

[0043] Compared with the prior art, the beneficial effects of the present invention are:

[0044] (1) The S-configuration nonacene-fused ring conjugated small molecule acceptor based on dithieno[3,2-b:2’,3’-d]pyrrole provided by the present invention has a unique nonacene-fused ring molecular structure. The extended conjugated backbone and enhanced ICT effect extend the light response range to the near-infrared band, and it has a high short-circuit current density and energy conversion efficiency when applied to organic solar cells;

[0045] (2) The S-configuration nonacene-fused ring conjugated small molecule acceptor based on dithieno[3,2-b:2’,3’-d]pyrrole provided by the present invention has a unique S configuration, better crystallinity and molecular packing, and has good donor-acceptor miscibility and device morphology when applied to organic solar cells;

[0046] (3) When the S-configuration nonacene-fused ring conjugated small molecule acceptor is applied to a semi-transparent organic solar cell device, it has a high transmittance (40 - 60%) and light utilization rate (4 - 5%) while maintaining a high energy conversion efficiency;

[0047] (4) At the same time, the large ring system of the nonacene-fused ring enhances the crystallinity of the molecule, which is beneficial to reducing the trap state density of the molecule. The prepared NIR OPDs have low dark current and high detectivity, a large cut-off bandwidth, and a wide linear dynamic range;

[0048] (5) The preparation method provided by the present invention has the advantages of simple process, high yield, low manufacturing cost, and suitability for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic chemical structure diagram of PBDB-T.

[0050] Figure 2 It is a schematic diagram of the normal device structure of an organic solar cell device with a blend of a near-infrared small molecule acceptor and PBDB-T as the active layer.

[0051] Figure 3 It is a schematic diagram of the structure of a semi-transparent organic solar cell device with a blend of a near-infrared small molecule acceptor and PBDB-T as the active layer.

[0052] Figure 4 It is a schematic chemical structure diagram of the donor PB2 and the acceptor FTCC-Br of the front cell active layer of a tandem cell device.

[0053] Figure 5 It is a schematic diagram of the normal device structure of a tandem organic solar cell device with a blend of a near-infrared small molecule acceptor and PBDB-T as the rear cell active layer.

[0054] Figure 6 It is the current-voltage curve of an organic solar cell with a blend of a near-infrared small molecule acceptor and PBDB-T as the active layer.

[0055] Figure 7 It is the wavelength-external quantum efficiency curve of an organic solar cell with a blend of a near-infrared small molecule acceptor and PBDB-T as the active layer.

[0056] Figure 8 It is the dark current density curve of an organic photodetector with a blend of Examples 1-4 and PBDB-T as the active layer.

[0057] Figure 9 It is the responsivity curve of an organic photodetector with a blend of Examples 1-4 and PBDB-T as the active layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0058] The present invention will be further described in detail below with reference to the drawings and embodiments, but the embodiments and protection scope of the present invention are not limited thereto. It should be noted that for the processes not specifically described in detail below, those skilled in the art can implement or understand them with reference to the prior art.

[0059] The practice of the present invention can adopt the conventional techniques of organic chemistry within the relevant technical fields. In the following examples, efforts are made to ensure the accuracy of the numbers used (including amounts, temperatures, reaction times, etc.), but some experimental errors and deviations should be taken into account. In the following examples, the temperatures used are expressed in °C, and the pressures are atmospheric pressure or close to atmospheric pressure. The solvents used are all of analytical grade or chromatographic grade, and all reactions are carried out in an inert gas atmosphere. Unless otherwise specified, all reagents are obtained through commercial channels.

[0060] Example 1

[0061] An S-configured nine-fused-ring conjugated small molecule acceptor BEHHD-C8-4F based on dithieno[3,2-b:2’,3’-d]pyrrole, whose structural formula is shown as follows:

[0062]

[0063] Its synthetic route is as follows:

[0064]

[0065] (1) Synthesis of Compound 3

[0066] Under a nitrogen atmosphere, Compound 1 (423 mg, 1.30 mmol), Compound 2 (2.25 g, 3.25 mmol), tris(dibenzylideneacetone)dipalladium (35 mg, 0.039 mmol) and tris(o-tolyl)phosphine (47 mg, 0.16 mmol) were dissolved in a mixed solvent of 7 mL of o-xylene and 0.7 mL of N,N-dimethylformamide (DMF). After refluxing at 110 °C for 24 h, it was cooled to room temperature, extracted with dichloromethane, the organic phase was washed with saturated brine, dried with anhydrous magnesium sulfate, and purified by column chromatography to obtain a blue-black solid product with a yield of 70%.

[0067] (2) Synthesis of Compound 4

[0068] Under a nitrogen atmosphere, compound 3 (865 mg, 0.89 mmol) and triphenylphosphine (2.33 g, 8.9 mmol) were dissolved in a reaction flask containing 14 mL of o-dichlorobenzene. After heating to 150 °C, the mixture was refluxed and stirred for 12 h. After cooling to room temperature, the solvent was removed by rotary evaporation under reduced pressure (without column chromatography, directly proceed to the next step). The above product and sodium hydroxide (285 mg, 7.12 mmol) were dissolved in a reaction flask containing 18 mL of DMF. Under nitrogen protection, 1-iodo-2-ethyldecane (1.87 g, 5.34 mmol) was added dropwise, and the reaction was refluxed at 90 °C overnight. The reaction mixture was cooled to room temperature, extracted with ethyl acetate and water, the organic phase was washed with saturated brine, dried over anhydrous magnesium sulfate, and purified by column chromatography to obtain a reddish-brown lacquer-like solid with a two-step yield of 30%.

[0069] (3) Synthesis of compound 5

[0070] Under a nitrogen atmosphere, ultradry phosphorus oxychloride (620 mg, 4.05 mmol) and ultradry DMF (296 mg, 4.05 mmol) were stirred at 0 °C for 30 min. Compound 4 (336 mg, 0.27 mmol) dissolved in 30 mL of ultradry 1,2-dichloroethane was added dropwise to the reaction flask. The temperature was raised to 90 °C and the reaction was carried out for 12 h. Saturated aqueous sodium bicarbonate was added and the mixture was stirred for another 2 h. After cooling to room temperature, it was extracted with dichloromethane, the organic phase was washed with saturated brine, dried over anhydrous magnesium sulfate, and purified by column chromatography to obtain an orange-red lacquer-like product with a yield of 75%.

[0071] (4) Synthesis of BTEHHD-4F

[0072] Under a nitrogen atmosphere, compound 5 (260 mg, 0.20 mmol) and compound 6 (184 mg, 0.80 mmol) were dissolved in 35 mL of chloroform, 2 mL of ultradry pyridine was added, and the reaction was carried out at 65 °C for 8 h. The reaction solution was concentrated and precipitated in 200 mL of anhydrous methanol, and the crude product solid was obtained by filtration. It was purified by column chromatography to obtain a blue-black solid product with a metallic luster and a yield of 95%.

[0073] Example 2

[0074] An S-configured nine-fused ring conjugated small molecule acceptor BEHHD-QC based on dithieno[3,2-b:2’,3’-d]pyrrole, whose structural formula is shown as follows:

[0075]

[0076] Its synthetic route is as follows:

[0077]

[0078] (1) Synthesis of Compound 8

[0079] Under a nitrogen atmosphere, Compound 1 (424 mg, 1.30 mmol), Compound 7 (1.89 g, 3.25 mmol), tris(dibenzylideneacetone)dipalladium(0) (35 mg, 0.039 mmol), and tris(o-tolyl)phosphine (47 mg, 0.16 mmol) were dissolved in a mixed solvent of 7 mL of o-xylene and 0.7 mL of DMF. After refluxing at 110 °C for 24 h, the reaction mixture was cooled to room temperature, extracted with dichloromethane, the organic phase was washed with saturated brine, dried over anhydrous magnesium sulfate, and purified by column chromatography to obtain a blue-black solid product with a yield of 70%.

[0080] (2) Synthesis of Compound 9

[0081] Compound 9 (665 mg, 0.89 mmol) and triphenylphosphine (2.33 g, 8.9 mmol) were dissolved in a reaction flask containing 14 mL of o-dichlorobenzene under nitrogen protection. After heating to 150 °C, the mixture was refluxed and stirred for 12 h. After cooling to room temperature, it was distilled under reduced pressure (without column chromatography, directly proceeding to the next step). The above product and sodium hydroxide (285 mg, 7.12 mmol) were dissolved in a reaction flask containing 18 mL of DMF. Under nitrogen protection, 1-iodo-2-ethylhexane (1.11 g, 5.46 mmol) was added dropwise, and the mixture was refluxed at 90 °C overnight. Then the reaction mixture was cooled to room temperature, extracted with ethyl acetate and water, and finally the organic layers were combined and the solvent was evaporated. The crude product was purified by silica gel column chromatography, and the eluent was evaporated to obtain a brownish-black lacquer-like solid with a two-step yield of 30%.

[0082] (3) Synthesis of Compound 10

[0083] Under a nitrogen atmosphere, Compound 9 (305 mg, 0.27 mmol) was dissolved in 25 mL of anhydrous THF and stirred at -78 °C for 20 min. A solution of 2.4 M n-BuLi in THF (0.27 mL, 0.68 mmol) was added dropwise to the reaction flask and stirred for 1.5 h. Then 1 M trimethyltin chloride (0.68 mL, 0.68 mmol) was added dropwise, and the temperature was raised to room temperature and reacted for 12 h. Saturated aqueous potassium fluoride solution was added and stirred for another 2 h. The mixture was extracted with dichloromethane, the organic phase was washed with saturated brine, dried over anhydrous magnesium sulfate, and purified by column chromatography to obtain an orange solid with a yield of 75%.

[0084] (4) Synthesis of Compound 12

[0085] Under a nitrogen atmosphere, compound 10 (292 mg, 0.20 mmol) and compound 11 (995 mg, 0.42 mmol) were dissolved in 20 mL of toluene. Tetrakis(triphenylphosphine)palladium (23 mg, 0.02 mmol) was added, and the reaction was carried out at 120 °C for 24 h. After cooling to room temperature, it was extracted with water and dichloromethane. The organic phase was precipitated with methanol, and the crude product solid was obtained by suction filtration. The crude product was separated and purified by column chromatography to obtain a blue-violet solid product with a metallic luster, and the yield was 70%.

[0086] (5) Synthesis of BEHHD-QC

[0087] Under a nitrogen atmosphere, compound 12 (289 mg, 0.20 mmol) and malononitrile (79.2 mg, 1.2 mmol) were dissolved in 40 mL of dichloromethane. A 1 M anhydrous dichloromethane solution of titanium tetrachloride (1.2 mL, 1.2 mmol) was added dropwise, and the mixture was stirred at room temperature for 20 min. Anhydrous pyridine (0.2 mL, 2.4 mmol) was added dropwise, and the reaction was carried out at room temperature for 2 h. It was extracted with water and dichloromethane. The organic phase was precipitated with methanol, and the crude product solid was obtained by suction filtration. The crude product was separated and purified by column chromatography to obtain a blue-violet solid product with a metallic luster, and the yield was 90%.

[0088] Example 3

[0089] A nine-fused-ring near-infrared small molecule acceptor PBEHPh-C8-4Cl based on dithieno[3,2-b:2’,3’-d]pyrrole, and its structural formula is as follows:

[0090]

[0091] Its synthetic route is as follows:

[0092]

[0093] (1) Synthesis of compound 14

[0094] Under a nitrogen atmosphere, compound 13 (448 mg, 1.16 mmol), compound 2 (2.01 g, 2.90 mmol), tris(dibenzylideneacetone)dipalladium (32 mg, 0.035 mmol) and tris(o-tolyl)phosphine (42 mg, 0.14 mmol) were dissolved in a mixed solvent of 7 mL of o-xylene and 0.7 mL of DMF. After refluxing at 110 °C for 24 h, it was cooled to room temperature, extracted with dichloromethane, the organic phase was washed with saturated brine, dried with anhydrous magnesium sulfate, and separated and purified by column chromatography to obtain a dark blue lacquer-like product, and the yield was 70%.

[0095] (2) Synthesis of compound 15

[0096] Compound 14 (835 mg, 0.81 mmol) and triphenylphosphine (2.12 g, 8.1 mmol) were dissolved in a reaction flask containing 14 mL of o-dichlorobenzene under nitrogen protection. After heating to 150 °C, the mixture was refluxed and stirred for 12 h. After cooling to room temperature, it was distilled under reduced pressure (without column chromatography, directly proceeding to the next step). The above product and sodium hydroxide (259 mg, 6.48 mmol) were dissolved in a reaction flask containing 18 mL of DMF. Under nitrogen protection, 1-iodo-2-ethylhexane (1.58 g, 4.86 mmol) was added dropwise. The reaction was refluxed at 90 °C overnight. Then the reactant was cooled to room temperature, extracted with ethyl acetate and water. Finally, the organic layers were combined and the solvent was evaporated. The crude product was purified by silica gel column chromatography. After evaporating the eluent, a dark brown lacquer-like solid was obtained with a two-step yield of 31%.

[0097] (3) Synthesis of Compound 16

[0098] Under a nitrogen atmosphere, ultradry phosphorus oxychloride (575 mg, 3.75 mmol) and ultradry DMF (274 mg, 3.75 mmol) were stirred at 0 °C for 30 min. Compound 15 (354 mg, 0.25 mmol) dissolved in 30 mL of ultradry 1,2-dichloroethane was added dropwise to the reaction flask. The temperature was raised to 90 °C and the reaction was carried out for 12 h. Saturated aqueous sodium bicarbonate was added and stirring was continued for 2 h. After cooling to room temperature, it was extracted with dichloromethane. The organic phase was washed with saturated brine and dried over anhydrous magnesium sulfate. The product was separated and purified by column chromatography to obtain an orange lacquer-like product with a yield of 78%.

[0099] (4) Synthesis of BOEHHD-C8-4Cl

[0100] Under a nitrogen atmosphere, compound 16 (294 mg, 0.20 mmol) and compound 17 (211 mg, 0.80 mmol) were dissolved in 35 mL of chloroform. 2 mL of ultradry pyridine was added and the reaction was carried out at 65 °C for 8 h. The reaction solution was concentrated and precipitated in 200 mL of anhydrous methanol. The crude product solid was obtained by filtration. The product was separated and purified by column chromatography to obtain a blue-black solid product with a metallic luster with a yield of 95%.

[0101] Example 4

[0102] A nine-fused-ring near-infrared small molecule acceptor OBMeEH-C8-NO based on dithieno[3,2-b:c2’,3’-d]pyrrole, whose structural formula is as follows:

[0103]

[0104] Its synthetic route is as follows:

[0105]

[0106] (1) Synthesis of Compound 19

[0107] Under a nitrogen atmosphere, Compound 1 (424 mg, 1.30 mmol), Compound 18 (2.20 g, 3.25 mmol), tris(dibenzylideneacetone)dipalladium(0) (35 mg, 0.039 mmol), and tris(o-tolyl)phosphine (47 mg, 0.16 mmol) were dissolved in a mixed solvent of 7 mL of o-xylene and 0.7 mL of DMF. After refluxing at 110 °C for 24 h, it was cooled to room temperature, extracted with dichloromethane, the organic phase was washed with saturated brine, dried over anhydrous magnesium sulfate, and purified by column chromatography to obtain a blue-black lacquer-like product with a yield of 72%.

[0108] (2) Synthesis of Compound 20

[0109] Compound 19 (855 mg, 0.91 mmol) and triphenylphosphine (2.38 g, 9.1 mmol) were dissolved in a reaction flask containing 15 mL of o-dichlorobenzene under nitrogen protection. After heating to 150 °C, it was refluxed and stirred for 12 h. After cooling to room temperature, it was distilled under reduced pressure (without column chromatography, directly proceeding to the next step). The above product and sodium hydroxide (291 mg, 7.28 mmol) were dissolved in a reaction flask containing 19 mL of DMF. Under nitrogen protection, 1-iodohexane (1.74 g, 5.46 mmol) was added dropwise, and the reaction was refluxed at 90 °C overnight. Then the reactant was cooled to room temperature, extracted with ethyl acetate and water, and finally the organic layers were combined and the solvent was evaporated. The crude product was purified by silica gel column chromatography, and the eluent was evaporated to obtain a brownish-black lacquer-like solid with a two-step yield of 31%.

[0110] (3) Synthesis of Compound 21

[0111] Under a nitrogen atmosphere, ultradry phosphorus oxychloride (638 mg, 4.20 mmol) and ultradry DMF (306 mg, 4.20 mmol) were stirred at 0 °C for 30 min. Compound 20 (292 mg, 0.28 mmol) dissolved in 30 mL of ultradry 1,2-dichloroethane was added dropwise to the reaction flask. The temperature was raised to 90 °C and the reaction was carried out for 12 h. After adding saturated aqueous sodium bicarbonate solution and continuing to stir for 2 h, it was cooled to room temperature, extracted with dichloromethane, the organic phase was washed with saturated brine, dried over anhydrous magnesium sulfate, and purified by column chromatography to obtain an orange lacquer-like product with a yield of 75%.

[0112] (4) Synthesis of BC1C6-Th-4CN

[0113] Under a nitrogen atmosphere, compound 21 (220 mg, 0.20 mmol) and compound 22 (195 mg, 0.80 mmol) were dissolved in 35 mL of chloroform, 2 mL of ultradry pyridine was added, and the reaction was carried out at 65 °C for 8 h. The reaction solution was concentrated and precipitated in 200 mL of anhydrous methanol, and the crude product solid was obtained by suction filtration. The product was separated and purified by column chromatography to obtain a blue-black solid product with a metallic luster, and the yield was 93%.

[0114] Example 5

[0115] A nine-fused-ring near-infrared small molecule acceptor CBEHHD-C8-ThH based on dithieno[3,2-b:2’,3’-d]pyrrole, and its structural formula is as follows:

[0116]

[0117] Its synthetic route is as follows:

[0118]

[0119] (1) Synthesis of compound 24

[0120] Under a nitrogen atmosphere, compound 23 (616 mg, 1.31 mmol), compound 2 (2.23 g, 3.28 mmol), tris(dibenzylideneacetone)dipalladium(0) (35 mg, 0.039 mmol) and tris(o-tolyl)phosphine (47 mg, 0.16 mmol) were dissolved in a mixed solvent of 7 mL of o-xylene and 0.7 mL of DMF. After refluxing at 110 °C for 24 h, it was cooled to room temperature, extracted with dichloromethane, the organic phase was washed with saturated brine, dried over anhydrous magnesium sulfate, and separated and purified by column chromatography to obtain a blue-black lacquer-like product, and the yield was 68%.

[0121] (2) Synthesis of compound 25

[0122] Compound 24 (993 mg, 0.89 mmol) and triphenylphosphine (2.33 g, 8.9 mmol) were dissolved in a reaction flask containing 14 mL of o-dichlorobenzene under nitrogen protection. After heating to 150 °C, it was refluxed and stirred for 12 h. After cooling to room temperature, it was distilled under reduced pressure (no column chromatography was required, and it was directly carried out in the next step). The above product and sodium hydroxide (285 mg, 7.12 mmol) were dissolved in a reaction flask containing 18 mL of DMF. Under nitrogen protection, 1-iodo-2-ethylhexane (1.03 g, 5.34 mmol) was added dropwise, and the reaction was refluxed at 90 °C overnight. Then the reactant was cooled to room temperature, extracted with ethyl acetate and water, and finally the organic layers were combined and the solvent was evaporated. The crude product was purified by silica gel column, and the eluent was evaporated to obtain a reddish-brown lacquer-like solid, and the two-step yield was 30%.

[0123] (3) Synthesis of Compound 26

[0124] Under a nitrogen atmosphere, ultradry phosphorus oxychloride (620 mg, 4.05 mmol) and ultradry DMF (296 mg, 4.05 mmol) were stirred at 0 °C for 30 min. A solution of Compound 25 (405 mg, 0.27 mmol) dissolved in 30 mL of ultradry 1,2-dichloroethane was added dropwise to the reaction flask. The temperature was raised to 90 °C and the reaction was carried out for 12 h. Saturated aqueous sodium bicarbonate solution was added and stirring was continued for 2 h. After cooling to room temperature, the mixture was extracted with dichloromethane. The organic phase was washed with saturated brine and dried over anhydrous magnesium sulfate. The product was separated and purified by column chromatography to obtain an orange lacquer-like product with a yield of 75%.

[0125] (4) Synthesis of CBEHHD-C8-ThH

[0126] Under a nitrogen atmosphere, Compound 26 (311 mg, 0.20 mmol) and Compound 6 (161 mg, 0.80 mmol) were dissolved in 35 mL of chloroform. 2 mL of ultradry pyridine was added and the reaction was carried out at 65 °C for 8 h. The reaction solution was concentrated and precipitated in 200 mL of anhydrous methanol. The crude product solid was obtained by filtration. The product was separated and purified by column chromatography to obtain a blue-violet solid product with a metallic luster and a yield of 90%.

[0127] The specific preparation process of each of the above organic solar cell devices is as follows:

[0128] A 40-nm PEDOT:PSS hole transport layer was spin-coated on ITO, and then a blend photoactive layer of about 100 nm of the polymer donor PBDB-T and the S-type small molecule acceptor was spin-coated. PNDIT-F3N was used as the cathode interface layer, and then 100 nm of Ag was evaporated to complete the preparation of the near-infrared organic photodetector. The structural formula of PBDB-T is as Figure 1 shown.

[0129] The above-mentioned near-infrared organic solar cell sequentially includes a transparent conductive anode, an anode interface layer, a donor-acceptor active layer, a cathode interface layer, and a cathode from bottom to top. The device structure is as Figure 2 shown. Voltage-current density curve tests and wavelength external quantum efficiency curve tests were carried out (see Figure 6 and Figure 7 ). The test data are shown in Table 1 below.

[0130] Table 1. Device parameter table of an organic solar cell with PBDB-T: nine-fused-ring small molecule as the active layer under simulated solar illumination (AM1.5G)

[0131]

[0132] The above data shows that the open-circuit voltages of non-fullerene small molecule acceptors with an A-DA’D-A structure based on dithieno[3,2-b:2’,3’-d]pyrrole S-type nine-fused-ring small molecule acceptors are all higher than 0.85 eV, and the short-circuit current densities are all higher than 24.5 mA cm -2 , and the prepared organic solar cell devices can be applied in different wavelength bands by regulating the bandgap of the acceptor material, and the highest PCE can reach 19.20%. This shows that introducing non-fullerene small molecules with an S-type nine-fused-ring structure based on dithieno[3,2-b:2’,3’-d]pyrrole is an effective strategy for improving the efficiency of organic solar cell devices.

[0133] The specific preparation process of each of the above semi-transparent organic solar cell devices is as follows:

[0134] Spin-coat a 40-nm PEDOT:PSS hole transport layer on ITO, then spin-coat a blend photoactive layer of about 100 nm of polymer donor PBDB-T and the nine-fused-ring small molecule acceptor, use PNDIT-F3N as the cathode interface layer, then evaporate 12 nm of Ag, and then evaporate 35 nm of MoO3 as the optical coupling layer, thus completing the preparation of the semi-transparent solar cell device.

[0135] The above semi-transparent organic solar cell includes a transparent conductive anode, an anode interface layer, a donor-acceptor active layer, a cathode interface layer, a cathode, and an optical coupling layer from bottom to top in sequence, and the device structure is as Figure 3 shown. Perform voltage-current density curve tests and transmittance tests on each device, and the test data is shown in Table 2 below.

[0136] Table 2. Parameters of semi-transparent organic solar cell devices with PBDB-T: near-infrared small molecules as the active layer

[0137]

[0138] The above data shows that non-fullerene small molecule acceptors with an A-DA’D-A structure based on dithieno[3,2-b:2’,3’-d]pyrrole S-type nine-fused-ring small molecule acceptors all have a narrow optical bandgap, and at the same time, the prepared semi-transparent organic solar cell devices can all obtain a relatively high average visible light transmittance, with the highest example reaching 44.01%; the corresponding light utilization rate is also increased accordingly, with the highest example reaching 5.01%. This shows that using S-type nine-fused small molecule acceptors in high-transmittance semi-transparent devices is an efficient and powerful strategy.

[0139] The specific preparation process of each of the above tandem organic solar cell devices is as follows:

[0140] The stacked device has the following structure: ITO / PEDOT:PSS / front cell active layer / connection layer / rear cell active layer / PDINO / Ag. Among them, PB2:FTCC-Br is used as the front cell active layer, and the chemical structure is as Figure 4 shown. The specific preparation process and flow of the front cell active layer are as follows: Spin-coat a 40-nm PEDOT:PSS hole transport layer on ITO, and then spin-coat a 100-nm blend film of PB2:FTCC-Br to complete the preparation of the front cell active layer; Preparation of the connection layer (ZnO / PEDOT:PSS / PMA): First, spin-coat a 20-nm ZnO nanoparticle layer on the active layer of the front cell, and then spin-coat 15 nm of PEDOT:PSS on the ZnO layer. Anneal the substrate at 100 °C for 5 min, and then spin-coat about 5 nm of phosphomolybdic acid (PMA) on PEDOT:PSS to complete the preparation of the connection layer; Use PBDB-T: near-infrared small molecule as the rear cell active layer, and the specific preparation method is the same as the preparation method of the above-mentioned organic solar cell device. After the preparation of the front cell, the connection layer, and the rear cell active layer is completed, spin-coat the electron transport layer PNDIT-F3N. Finally, deposit the Ag electrode by evaporation in high vacuum to obtain the stacked cell device.

[0141] The device structure of the stacked cell is as Figure 5 shown, specifically ITO / PEDOT:PSS / PB2:FTCC-Br / ZnO / PEDOT:PSS / PBDB-T:S-type nine-fused-ring small molecule acceptor / PNDIT-F3N / Ag. Perform voltage-current density curve testing on it, and the test data are shown in Table 3 below. Table 3: Device parameter table of the stacked organic solar cell based on PBDB-T and near-infrared small molecule acceptor under simulated solar illumination (AM1.5G)

[0142]

[0143] The above data show that non-fullerene small molecule acceptors with an A-DA’D-A structure based on nine-fused-ring near-infrared small molecule acceptors of dithieno[3,2-b:2’,3’-d]pyrrole and PBDB-T can be used as the rear cell in stacked cell devices to obtain an energy conversion efficiency of more than 20%. This is attributed to the fact that the prepared materials can form complementary absorption with the front cell active layer, and the rear cell provides excellent short-circuit current density and photovoltaic performance.

[0144] The specific preparation process of each of the above near-infrared organic photodetectors is as follows:

[0145] A 40-nm PEDOT:PSS hole transport layer was spin-coated on ITO, and then a blend photoactive layer of about 100 nm of the polymer donor PBDB-T and the near-infrared small molecule acceptor was spin-coated. PNDIT-F3N was used as the cathode interface layer, and then 100 nm of Ag was evaporated to complete the preparation of the near-infrared organic optoelectronic detector.

[0146] The near-infrared organic optoelectronic detector includes, from bottom to top, a transparent conductive anode, an anode interface layer, a donor-acceptor active layer, a cathode interface layer, and a cathode. The device structure is as Figure 2 shown. The external quantum efficiency (EQE) and dark current density (J d ) of the above organic optoelectronic detector were measured under a 0 V bias, and the corresponding responsivity R and detectivity D* were calculated. The specific performance parameters are shown in Table 2.

[0147] Among them, the responsivity R refers to the ratio of the photocurrent of the optoelectronic detector to the incident light intensity, and the unit is A / W. The calculation formula of R is as follows:

[0148]

[0149] Among them, EQE is directly proportional to R, and both reflect the efficiency of converting photons into electrons. The detectivity D* is defined as the reciprocal of the noise equivalent power (NEP) and is an index to measure the ability of the detector to detect the minimum incident light signal. The unit is Jones. The calculation formula of D* is as follows:

[0150]

[0151] Among them, R is the responsivity, q is the charge, and J d is the dark current.

[0152] Figure 8 , Figure 9 shows the EQE, dark current density, and responsivity of several normal organic optoelectronic detector devices obtained by using the S-type nine-fused-ring small molecule acceptors obtained in Examples 1-4 as the acceptor materials and PBDB-T as the donor material. The device data obtained are shown in Table 4.

[0153] Table 4 Device parameters of organic optoelectronic detectors with PBDB-T: near-infrared small molecules as the active layer under a 0 V bias

[0154]

[0155] The above data show that the detection range of the non-fullerene small molecule acceptor with the A-DA’D-A structure of the S-type nine-fused-ring small molecule acceptor based on dithieno[3,2-b:2’,3’-d]pyrrole is around 1000 nm. Moreover, under a 0 V bias, the order of magnitude of the dark current density is all in 10-11 Hereinafter, the minimum can reach 4.73×10 -12 A cm -2 . The detectivities of the prepared detectors are all above 10 13 Jones, and the highest detectivity can reach 4.80×10 14 Jones under 0V. In addition, the prepared NIR OPDs have low dark current and high detectivity near 1000nm, a relatively large cut-off bandwidth and a wide linear dynamic range, which indicates that the introduction of the nine-fused ring structure of dithieno[3,2-b:2’,3’-d]pyrrole is an effective method for inventing high-performance near-infrared modular non-fullerene small molecule acceptors.

[0156] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limiting the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation manners here. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A class of nine-fused-ring conjugated small molecule acceptors with S configuration, characterized in that, The small molecule acceptor is an S-type nine-fused-ring small molecule acceptor based on dithieno[3,2-b:2’,3’-d]pyrrole, having the structure shown in Formula 1: Among them, represents different substituted benzene electron-donating units; A represents an electron-withdrawing unit; R1, R2, R3, and R4 are each independently selected from H, halogen, a straight-chain or branched-chain alkyl group having 1 to 50 carbon atoms, an ester group, an alkoxy group, an alkylthio group, or an alkylsilyl group; the halogen is selected from F, Cl, Br, or I.

2. The class of nine-fused-ring conjugated small molecule acceptors with S configuration according to Claim 1, wherein: A is selected from any one of the following structures, where the dotted line indicates the connection position: Among them, R 5-16 are each independently selected from H, a halogen, a linear or branched alkyl group having 1 to 50 carbon atoms, an ester group, an alkoxy group, an alkylthio group, or an alkylsilyl group, and the halogen is selected from F, Cl, Br, or I.

3. The preparation method of the nine-fused-ring conjugated small molecule acceptor with S configuration according to any one of Claims 1-2, comprising the following steps: 1) Reacting the p-substituted benzene compound B with the stannylated dithieno[3,2-b:2’,3’-d]pyrrole compound C through a Stille coupling reaction to obtain compound D; 2) Performing Cadogan cyclization on compound D to obtain compound E; 3) Performing a nucleophilic substitution reaction on compound E and the haloalkane to obtain compound F; Among them, The selected haloalkane is R2X, and X is either bromine or iodine; 4) Obtaining compound G by subjecting compound F to a Vilsmeier-Haack reaction; 5) Reacting compound G with the terminal group A through a Knoevenagel reaction to obtain the S-type nine-fused-ring near-infrared small molecule acceptor.

4. According to the preparation method described in Claim 3, wherein: In step 1), in the Stille coupling reaction, o-xylene is used as the solvent, tris(dibenzylideneacetone)dipalladium is used as the catalyst, and tris(o-tolyl)phosphine is used as the ligand; the addition amount of the catalyst is 3%-10% of the total molar amount of the substrates, and the addition amount of the ligand is 10%-20% of the total molar amount of the substrates; the molar ratio of compound B to the stannylated dithieno[3,2-b:2’,3’-d]pyrrole compound C is 1:2.5 - 1:3.5; the reflux reaction is carried out at a temperature of 100 - 120°C for 24 - 48 hours.

5. According to the preparation method described in Claim 3, wherein: In step 2), the conditions for the Cadogan cyclization reaction are: ultraviolet light irradiation, o-dichlorobenzene as the solvent, and the molar amount of triphenylphosphine to compound D is 10:1; the reflux reaction is carried out at 120 - 160°C for 10 - 24 hours.

6. According to the preparation method described in Claim 3, wherein: In step 3), the conditions for the nucleophilic substitution reaction are: using N,N-dimethylformamide (DMF) as the solvent, sodium hydroxide as the base, the molar ratio of sodium hydroxide to compound E is 10:1, the molar ratio of the haloalkane to compound E is 6:1 - 8:1, and the reflux reaction is carried out at a temperature of 80 - 100°C for 5 - 24 hours.

7. According to the preparation method described in Claim 3, wherein: In step 4), the conditions for the Vilsmeier-Haack reaction are: 1,2-dichloroethane as the solvent, the molar ratio of compound F to phosphorus oxychloride and DMF is 1:15:15 - 1:20:20; the reflux reaction is carried out at 80 - 90°C for 8 - 12 hours; then saturated sodium bicarbonate aqueous solution is added and the reflux reaction is continued at 80 - 90°C for 2 - 3 hours; In step 5), the conditions for the Knoevenagel reaction are as follows: the solvent is chloroform, pyridine is used as the base source, and the molar ratio of compound H to terminal A is 1:3.5 - 1:4.5; the reaction is refluxed at 60 - 70 °C for 5 - 12 hours.

8. The application of an S-shaped nine-fused-ring small molecule acceptor based on dithieno[3,2-b:2’,3’-d]pyrrole according to any one of claims 1 - 2 in an organic solar cell, a tandem organic solar cell, a semi-transparent organic solar cell, and a near-infrared organic optoelectronic detector.

9. The application according to claim 5, wherein: In the organic solar cell, tandem organic solar cell, and near-infrared organic optoelectronic detector, it includes an anode, a cathode, and one or more inorganic / organic compound layers disposed between the two electrodes. The inorganic / organic compound layer includes at least one of a hole transport layer, an active layer, and an electron transport layer. The active layer in the organic compound layer includes an S-shaped nine-fused-ring small molecule acceptor based on dithieno[3,2-b:2’,3’-d]pyrrole.

10. The application according to claim 5, wherein: The semi-transparent organic solar cell includes an anode, a cathode, an optical coupling layer, and one or more organic compound layers disposed between the two electrodes. The organic compound layer includes at least one of a hole transport layer, an active layer, and an electron transport layer. The active layer in the organic compound layer contains an S-shaped nine-fused-ring small molecule acceptor based on dithieno[3,2-b:2’,3’-d]pyrrole.

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