An asymmetric benzoselenophene benzoselenophenobenzene derivative, and a preparation method and photoelectric application thereof

Abstract

This invention discloses an asymmetric benzo[selenophene]benzo[selenophene]benzene derivative, its preparation method, and its optoelectronic applications. The structural formula of the asymmetric benzo[selenophene]benzo[selenophene]benzene derivative is shown in Formula I. In Formula I, R and R' are each independently selected from H, C1-C24 alkyl, C2-C24 alkenyl, C2-C24 alkynyl, and C3-C24 cycloalkyl; n is an integer from 1 to 5. The asymmetric BSBS derivative molecule of this invention exhibits excellent thermal stability in both small molecule materials and devices. Solar-blind zone photodetectors prepared based on the asymmetric BSBS derivative material show strong selective response to the solar-blind zone (wavelength 200-280 nm), stable electrical properties, fast response speed, and high sensitivity.

Description

Technical Field

[0001] This invention relates to an asymmetric benzo[selen]phene benzo[selen]phene derivative, its preparation method and optoelectronic applications, belonging to the field of organic semiconductor materials technology. Background Technology

[0002] With the rapid development of organic electronics, organic semiconductor materials have been widely used due to their advantages such as tunable structure, light weight, solution processability, flexibility, and stretchability. The optoelectronic properties of semiconductors can be controlled through the design and synthesis of semiconductor molecules. Among them, compared to fused-ring compounds such as anthracene and pentanebenzene, heterocyclic aromatic hydrocarbon compounds, represented by benzothiophene-thiophene-benzene (BTBT), have advantages such as lower HOMO energy levels and increased optical energy bandwidth, making BTBT and its derivatives star molecules in organic semiconductor materials. However, the poor material stability of these molecules limits further development. Compared to BTBT, benzoselenophene-benzoselenophene (BSBS) molecules replace the S atoms with Se atoms, which does not significantly affect the electrical properties while improving stability to some extent. Therefore, derivatizing BSBS materials with suitable conjugation lengths to construct BSBS derivatives with aromatic substitution is also an important way to obtain high-performance organic semiconductor materials.

[0003] Currently, there are few reported aromatic-substituted BSBS derivatives, especially asymmetric aromatic-substituted BSBS derivatives. This is mainly because, compared to symmetrical aromatic-substituted BSBS derivatives, asymmetric aromatic-substituted BSBS derivatives are more complex to synthesize and purify, resulting in lower yields and thus limited research. However, their electrical properties are not inferior to their symmetrical derivatives. Furthermore, asymmetric aromatic-substituted BSBS derivatives exhibit strong absorption of specific wavelengths of light. Therefore, developing and applying novel asymmetric BSBS derivative semiconductor materials to fabricate high-performance optical and electrical devices is of great significance. Summary of the Invention

[0004] The purpose of this invention is to provide an asymmetric benzo[seleno]phen(BSBS) derivative, its preparation method, and its optoelectronic applications. This asymmetric BSBS derivative is a type of p-type organic semiconductor material with strong light absorption and high thermal stability. The synthesis method is simple and inexpensive. By applying the asymmetric BSBS derivative to the response of deep ultraviolet light in the solar blind zone (200-280nm), a solar blind zone photodetector was prepared, which exhibits high photoresponsivity and photosensitivity to solar blind zone light.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides an asymmetric benzo[a]selenophene (BSBS) derivative, the structural formula of which is shown in Formula I:

[0007]

[0008] In Formula I, R and R' are each independently selected from H, C1-C24 alkyl, C2-C24 alkenyl, C2-C24 alkynyl, and C3-C24 cycloalkyl; n is an integer from 1 to 5. Preferably, in Formula I, R and R' are each independently H, n-hexyl, n-octyl, or n-decyl; n = 2 or 3.

[0009] In a second aspect, the present invention provides a method for preparing the asymmetric benzo[a]selenphene benzo[a]selenphene derivative as described in any of the above claims, comprising the following steps:

[0010] (1) The compound shown in Formula II was reacted with liquid bromine in a solvent to obtain the compound shown in Formula III;

[0011]

[0012] In equations II and III, the definition of R is the same as in equation I;

[0013] (2) Under an inert atmosphere, the compound shown in Formula IV was reacted with pinacol diboronic acid ester in a solvent in the presence of a catalyst to obtain the compound shown in Formula V.

[0014]

[0015] In equations IV and V, R' and n are defined as in equation I;

[0016] (3) Under an inert atmosphere, the compound shown in Formula III and the compound shown in Formula V are reacted in a solvent with the action of a target catalyst and carbonate to obtain the asymmetric benzo[selen]phene benzo[selen]phene derivative shown in Formula I.

[0017] In the above preparation method, in step (1), the molar ratio of the compound shown in Formula II to liquid bromine can be 1:(0.7~1);

[0018] In step (1), the reaction temperature is 20-25°C and the time is 1-5 hours;

[0019] In step (1), the solvent is dichloromethane or N,N-dimethylformamide (DMF).

[0020] In the above preparation method, in step (2), the molar ratio of the compound shown in Formula IV to the pinacol diboronic acid ester is 1:(1-3);

[0021] In step (2), the catalyst is 2-biscyclohexylphosphine-2',6'-dimethoxy-1,1'-diphenyl (S-phos), palladium catalyst, and potassium acetate, wherein the molar ratio of the compound shown in Formula IV, 2-biscyclohexylphosphine-2',6'-dimethoxy-1,1'-diphenyl, palladium catalyst, and potassium acetate is 1:(0.1~0.2):(0.04~0.1):(2~5);

[0022] The target catalyst is palladium acetate or 1,1'-bis(diphenylphosphino)ferrocene)palladium dichloride ((PdCl2(dppf)));

[0023] In step (2), the reaction temperature is 70–90°C and the time is 24–48 h;

[0024] In step (2), the solvent is tetrahydrofuran or N,N-dimethylformamide (DMF).

[0025] In the above preparation method, in step (3), the molar ratio of the compound shown in formula III to the compound shown in formula V is 1:(1~1.3);

[0026] In step (3), the molar ratio of the compound shown in Formula III, the target catalyst, and the carbonate is 1:(0.03~0.06):(4~8);

[0027] In step (3), the target catalyst is at least one of tetratriphenylphosphine palladium and 1,1'-bis(diphenylphosphine)ferrocene)palladium dichloride ((PdCl2(dppf))).

[0028] In step (3), the carbonate is at least one of potassium carbonate, sodium carbonate, and cesium carbonate;

[0029] In step (3), the reaction temperature is 80-90°C and the time is 12-24 hours;

[0030] In step (3), the solvent is composed of toluene, ethanol and water, and the volume ratio of toluene, ethanol and water is preferably (2-6):1:1.

[0031] Thirdly, the present invention provides the application of the asymmetric benzo[a]selenphene benzo[a]selenphene derivative described in any of the above claims in solar blind zone photodetection or in the preparation of solar blind zone photodetectors, wherein the solar blind zone is deep ultraviolet light with a wavelength of 200-280 nm.

[0032] Fourthly, the present invention provides a solar blind zone photodetector, comprising an organic semiconductor active layer, wherein the organic semiconductor active layer comprises the asymmetric benzo[a]selenide benzo[a]selenide benzo[a]benzene derivative semiconductor material described in any one of the preceding claims.

[0033] In the aforementioned solar blind zone photodetector, the solar blind zone photodetector has a bottom-gate top-contact configuration, including, from bottom to top, a gate electrode layer, a gate insulating layer, an organic semiconductor active layer, and source and drain electrode layers;

[0034] The gate electrode is made of Si;

[0035] The gate insulating layer is a silicon oxide layer (SiO2) or a composite insulating layer modified with a silicon oxide self-assembled layer, and the general formula of the silicon oxide self-assembled layer is shown in Formula VI:

[0036]

[0037] In formula VI, R1 is any one of C1-C24 alkyl, C1-C24 cycloalkyl, C1-C24 perfluoroalkyl, and phenyl.

[0038] The thickness of the organic semiconductor active layer is 30–50 nm;

[0039] The electrodes in the source and drain electrode layers are made of gold, silver, or platinum.

[0040] Fifthly, the present invention provides a method for fabricating the solar blind zone photodetector, comprising the following steps:

[0041] (1) The gate insulating layer is prepared on the gate electrode layer;

[0042] (2) The organic semiconductor active layer is prepared on the gate insulating layer by spin coating, drop casting, vapor deposition, scraping coating and printing methods;

[0043] (3) The source and drain electrode layers are prepared on the active layer of the organic semiconductor by means of transferring metal electrodes or evaporating metal to obtain the solar blind zone photodetector.

[0044] Compared with the prior art, the present invention has the following beneficial effects:

[0045] (1) The asymmetric BSBS derivative molecules prepared are simple and efficient to synthesize, have low synthesis cost, and are molecularly stable.

[0046] (2) The asymmetric organic semiconductor small molecule material prepared is specifically an asymmetric BSBS derivative molecule, and both the small molecule material and the device have good thermal stability.

[0047] (3) The solar blind zone photodetector based on asymmetric BSBS derivative material has a strong selective response to the solar blind zone (wavelength of 200-280nm) and can directly respond to light through the electrical properties of the transistor, including leakage current, gate voltage, etc.

[0048] (4) The solar blind zone photodetector prepared based on asymmetric BSBS derivative materials has stable electrical properties, fast response speed and high sensitivity. Attached Figure Description

[0049] Figure 1 The UV-Vis absorption spectra of the C6-BSBSN-C6 molecule in dichloromethane solution and the thin film in Example 1 are shown.

[0050] Figure 2 The thermogravimetric (TGA) spectrum of the C6-BSBSN-C6 molecule.

[0051] Figure 3 This is a schematic diagram of the structure of the solar blind zone photodetector of the present invention.

[0052] Figure 4 The transfer curves of the C6-BSBSN-C6 photodetector under different light intensities are shown.

[0053] Figure 5 The time-correlated optical response curves of the C6-BSBSN-C6 photodetector under different light intensities are shown.

[0054] Figure 6 The transition curves of the C6-BSBSN-C6 photodetector under dark and sunlight conditions are shown.

[0055] Figure 7 The photosensitiveness (P) and photoresponsivity (R) of the C6-BSBSN-C6 photodetector vary with light intensity.

[0056] Figure 8 The UV-Vis absorption spectra of BSBSA-C8 molecules in dichloromethane solution and thin films are shown.

[0057] Figure 9 The thermogravimetric (TGA) spectrum of the BSBSA-C8 molecule.

[0058] Figure 10 The transfer curves of the BSBSA-C8 photodetector under different light intensities are shown.

[0059] Figure 11 The transition curves of the C8-BSBSN-C8 ​​photodetector under dark conditions and sunlight are shown.

[0060] Figure 12 The photosensitiveness (P) and photoresponsivity (R) of the BSBSA-C8 photodetector vary with light intensity. Detailed Implementation

[0061] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with the accompanying drawings. In the description of this invention, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the system or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0062] As described in the background section, the thermal stability and light absorption performance of existing organic semiconductor materials need further improvement. Therefore, in the first part, this invention provides an asymmetric benzo[a]selenphene(BSBS) derivative, the structural formula of which is shown in Formula I:

[0063]

[0064] In Formula I, R and R' are each independently selected from H, C1-C24 alkyl, C2-C24 alkenyl, C2-C24 alkynyl, and C3-C24 cycloalkyl; n is an integer from 1 to 5.

[0065] Based on the above technical solutions, the non-stacked BSBS derivative of the present invention is a type of p-type organic semiconductor material. This type of material has good stability, strong light absorption and wide band gap.

[0066] According to the present invention, preferably, R and R' are each independently selected from H, C1 to C10 alkyl groups; n is an integer from 1 to 3. Wherein, C1 to C10 alkyl groups refer to straight-chain or branched alkyl groups having 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 carbon atoms in their carbon chain, including but not limited to methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, 2-pentyl, 2-methylbutyl, 3-methylbutyl, 1,2-dimethylpropyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl, 1-ethylpropyl, and n-hexyl. 2-Hexyl, 2-methylpentyl, 3-methyl-pentyl, 4-methylpentyl, 1,2-dimethylbutyl, 1,3-dimethylbutyl, 2,3-dimethylbutyl, 1,1-dimethylbutyl, 2,2-dimethylbutyl, 3,3-dimethylbutyl, 1,1,2-trimethylpropyl, 1,2,2-trimethylpropyl, 1-ethylbutyl, 2-ethylbutyl, 1-ethyl-2-methylpropyl, n-heptyl, n-octyl, n-nonyl, n-decyl, etc. More preferably, in Formula I, R and R' are each independently H, n-hexyl, n-octyl, or n-decyl; n = 2 or 3. As an example, the structural formula of the asymmetric BSBS derivative is as shown in Formula I-1 or Formula I-2 below:

[0067]

[0068] In this invention, Formula I-1 is named C6-BSBSN-C6, and Formula I-2 is named BSBSA-C8.

[0069] In the second part, the present invention provides a method for preparing the asymmetric benzo[a]selenphene benzo[a]selenphene derivative as described in any of the above claims, comprising the following steps:

[0070] (1) The compound shown in Formula II was reacted with liquid bromine in a solvent to obtain the compound shown in Formula III;

[0071]

[0072] In equations II and III, the definition of R is the same as in equation I;

[0073] (2) Under an inert atmosphere, the compound shown in Formula IV was reacted with pinacol diboronic acid ester in a solvent in the presence of a catalyst to obtain the compound shown in Formula V.

[0074]

[0075] In equations IV and V, R' and n are defined as in equation I;

[0076] (3) Under an inert atmosphere, the compound shown in Formula III and the compound shown in Formula V are reacted in a solvent with the aid of a palladium catalyst and a carbonate to obtain the asymmetric benzo[selen]phene benzo[selen]phene derivative shown in Formula I.

[0077] Based on the above technical solutions, the synthesis method of the present invention is simple and low in cost.

[0078] According to the present invention, in step (1), the molar ratio of the compound shown in Formula II to liquid bromine can be 1:(0.7-1), including but not limited to 1:0.9; the reaction temperature is 20-25°C, and the time is 1-5 h, specifically, the reaction can be carried out at room temperature (25°C) for 3 h; the solvent is dichloromethane or N,N-dimethylformamide (DMF). In a specific embodiment of the present invention, the specific operation of step (1) is as follows: the compound shown in Formula II is dissolved in a solvent, and liquid bromine is slowly added dropwise to carry out the reaction. The method also includes the following post-processing steps: after the reaction is completed, methanol is added, a precipitate is formed, filtered, washed with anhydrous ethanol, and further recrystallized with chloroform / methanol to obtain the compound shown in Formula III.

[0079] According to the present invention, in step (2), the molar ratio of the compound shown in Formula IV to the pinacol diboron ester can be 1:(1-3), including but not limited to 1:1.5; the catalyst is 2-dicyclohexylphosphine-2',6'-dimethoxy-1,1'-diphenyl (S-phos), a target catalyst, and potassium acetate, wherein the molar ratio of the compound shown in Formula IV, 2-dicyclohexylphosphine-2',6'-dimethoxy-1,1'-diphenyl, the target catalyst, and potassium acetate is 1:(0.1-0.2):(0.04-0.1):(2-5), including but not limited to 1:0.1:0. .05:4; the target catalyst is palladium acetate or 1,1'-bis(diphenylphosphino)ferrocene)palladium dichloride ((PdCl2(dppf))); the reaction temperature is 70-90℃, and the time is 24-48h, such as reflux at 80℃ for 24h; the solvent is tetrahydrofuran or N,N-dimethylformamide (DMF); the method also includes the following post-treatment steps: after the reaction is completed, the solvent is removed by rotary evaporation, water and CH2Cl2 are added sequentially for extraction, then the organic phase is washed with saturated NaCl solution, filtered, the filtrate is filtered, and the filtrate is mixed with silica gel powder and passed through a column to obtain the compound shown in Formula V.

[0080] According to the present invention, in step (3), the molar ratio of the compound shown in Formula III to the compound shown in Formula V can be 1:(1-1.3), including but not limited to 1:1 and 1:1.1; the molar ratio of the compound shown in Formula III, the target catalyst, and the carbonate can be 1:(0.03-0.06):(4-8), including but not limited to 1:0.05:4; the target catalyst is at least one of tetrakis(triphenylphosphine)palladium and 1,1'-bis(diphenylphosphine)ferrocene)palladium dichloride ((PdCl2(dppf))); the carbonate is carbon The reaction mixture contains at least one of potassium carbonate, sodium carbonate, and cesium carbonate; the reaction temperature can be 80–90°C, and the reaction time can be 12–24 h, such as reacting at 90°C for 24 h; the solvent is composed of toluene, ethanol, and water, and the volume ratio of toluene, ethanol, and water is preferably (2–6):1:1, such as 4:1:1; the method further includes the following post-processing steps: after the reaction is completed, the reaction system is filtered, the filter residue is washed sequentially with anhydrous ethanol and dichloromethane, and the crude product is sublimated and purified to obtain the asymmetric benzo[selen]phene benzo[selen]phene derivative shown in Formula I.

[0081] It is understood that in this invention, the inert atmosphere may be a nitrogen or argon atmosphere.

[0082] Part Three: This invention provides the application of the asymmetric benzo[seleno]phene derivative described in any of the above claims in solar-blind region photodetectors or in the preparation of solar-blind region photodetectors, wherein the solar-blind region is deep ultraviolet light with a wavelength of 200–280 nm. Based on the above technical solutions, the solar-blind region photodetector prepared based on the asymmetric BSBS derivative of this invention has a strong selective response to deep ultraviolet light in the solar-blind region (no response to white light). Specifically, this molecule has strong absorption in the solar-blind region (200–280 nm); and the absorption wavelength of the thin film in the solar-blind region can specifically be 270 nm or 264 nm.

[0083] Fourthly, the present invention provides a solar blind zone photodetector, comprising an organic semiconductor active layer, wherein the organic semiconductor active layer comprises the asymmetric benzo[a]selenophene benzo[a]selenophene derivative described in any of the above-mentioned embodiments. Based on the above technical solutions, the solar blind zone photodetector of the present invention uses the asymmetric BSBS derivative as the active layer, exhibiting high photoresponsivity and photosensitivity to solar blind zone light.

[0084] According to the present invention, based on the strong absorption of the asymmetric benzo[a]selenphene benzo[a]selenphene benzo[a]benzene derivative in the solar blind region, the solar blind region photodetector can be configured as a bottom-gate top-contact structure, a top-gate top-contact structure, etc. For example, such as Figure 4 As shown, the solar blind zone photodetector can be a bottom-gate top-contact configuration, comprising, from bottom to top, a gate electrode layer, a gate insulating layer, an organic semiconductor active layer, and source and drain electrode layers. As an example, the gate electrode is made of Si. The gate insulating layer is a silicon oxide layer or a composite insulating layer with a silicon oxide-modified self-assembled layer. The general formula for the silicon oxide self-assembled layer is shown in Formula VI:

[0085]

[0086] In Formula VI, R1 is any one of C1-C24 alkyl, C1-C24 cycloalkyl, C1-C24 perfluoroalkyl, and phenyl; preferably, the self-assembled layer is any one of n-octadecyltrichlorosilane (OTS), perfluorododecyltrichlorosilane (PTLS), and phenyltrichlorosilane (PTS); wherein, the gate electrode can be any commercially available Si wafer with no thickness limit; the thickness of the gate insulating layer can be 200-700 nm, such as 500 nm; the thickness of the organic semiconductor active layer is 30-50 nm, such as 30 nm; the electrode material in the source and drain electrode layers is gold, silver, or platinum, and the channel length and width can be 240 μm and 30 μm, respectively.

[0087] Fifthly, the present invention provides a method for fabricating the solar blind zone photodetector, comprising the following steps: (1) fabricating the gate insulating layer on the gate electrode layer; (2) fabricating the organic semiconductor active layer on the gate insulating layer by spin coating, drop casting, evaporation, blade coating, or printing; (3) fabricating source and drain electrode layers on the organic semiconductor active layer by transferring metal electrodes or evaporating metal, thereby obtaining the solar blind zone photodetector. Based on the above technical solutions, the present invention can fabricate the active layer and source and drain electrode layers in various ways.

[0088] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.

[0089] Unless otherwise specified, the methods used in the following embodiments are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following embodiments are commercially available.

[0090] Example 1 illustrates the preparation process of the C6-BSBSN-C6 molecule, an asymmetric BSBS derivative with bilateral alkyl chain substitution, and the fabrication process of a solar-blind zone photodetector based on the C6-BSBSN-C6 thin film, using the C6-BSBSN-C6 molecule as an example.

[0091] I. Preparation of C6-BSBSN-C6 molecules

[0092] The C6-BSBSN-C6 molecule was prepared according to the synthetic route shown below:

[0093]

[0094] The specific steps are as follows:

[0095] (1) Preparation of 2-pentyl ketone benzo[selenophene]

[0096] In a 50 mL three-necked flask, benzo[a]selenide (BSBS) (5 mmol) was dissolved in 30 mL of dichloromethane. The reaction was cooled to -5 °C, and aluminum trichloride (7.5 mmol) was slowly added and stirred for 1 h. The reaction was then cooled to -67 °C, and hexanoyl chloride (5.5 mmol) was slowly added and stirred at this temperature for 3 h. After the reaction was completed, water was added, and a white precipitate formed. The precipitate was filtered, and then toluene was added for recrystallization to obtain 2-pentyl ketone benzo[a]selenide.

[0097] The structural confirmation data for this product are shown below:

[0098] Mass spectrometry: EI:M + 433.

[0099] 1H NMR spectrum: 1 H NMR(400MHz,Chloroform-d)δ7.97–7.93(m,1H),7.88–7.82(m,2H),7.81(dd,J=7.6,2.1Hz,1H),7.73(dd,J=7.3,1.6Hz,1H),7.41(td ,J=7.3,1.4Hz,1H),7.30(td,J=7.2,1.5Hz,1H),2.93(t,J=7.9Hz,2H),1.66(d,J=15.5Hz,1H),1.39–1.31(m,4H),0.92–0.86(m,3H).

[0100] (2) Preparation of 2-hexylbenzoselenophene

[0101] In a 50 mL three-necked flask, 3 mmol of 2-pentyl ketone benzo[a]selenide and 27 mmol of sodium borohydride were dissolved in 20 mL of tetrahydrofuran. Then, 15 mmol of aluminum trichloride was slowly added, and the mixture was heated to 70 °C and reacted for 5 h. After the reaction was complete, the mixture was slowly cooled to room temperature (20 °C), and a large amount of gas was generated upon slow addition of water. The mixture was then extracted three times with ethyl acetate, the solvent was removed by rotary evaporation, and finally recrystallized from dichloromethane / ethanol to obtain 2-hexylbenzo[a]selenide.

[0102] The structural confirmation data for this product are shown below:

[0103] Mass spectrometry: EI:M + 420.

[0104] 1H NMR spectrum: 1 H NMR(400MHz,Chloroform-d)δ7.85(dd,J=7.2,1.3Hz,1H),7.73(dd,J=7.3,1.6Hz,1H),7.64–7.56(m,2H),7.41(td,J=7.3,1.4Hz,1H),7.30(td, J=7.2,1.5Hz,1H),7.11(dd,J=7.4,2.3Hz,1H),2.55(t,J=8.0Hz,2H),1.59(ddd,J=15.0,8.0,6.9Hz,2H),1.37–1.25(m,6H),0.93–0.84(m,3H).

[0105] (3) Preparation of 2-bromo-7-hexylbenzoselenophene

[0106] In a 50 mL three-necked flask, 2-hexylbenzoselenide (5 mmol) was dissolved in 30 mL of dichloromethane. Then, liquid bromine (0.23 mL, 4.5 mmol) was dissolved in 10 mL of dichloromethane and slowly added to the reaction mixture using a constant-pressure dropping funnel. The reaction was carried out at room temperature in the dark for 3 h. After the reaction was completed, methanol was added, and a precipitate formed. The precipitate was filtered, washed with anhydrous ethanol, and further recrystallized from chloroform / methanol to obtain 2-bromo-7-hexylbenzoselenide.

[0107] The structural confirmation data for this product are shown below:

[0108] Mass spectrometry: EI:M + 497.

[0109] 1H NMR spectrum: 1 H NMR (400MHz, Chloroform-d) δ7.92(d,J=2.2Hz,1H),7.67(d,J=7.7Hz,1H),7.62(d,J=7.4Hz,1H),7.58(d,J=2.2Hz,1H),7.52(dd,J=7 .7,2.2Hz,1H),7.11(dd,J=7.4,2.3Hz,1H),2.55(t,J=8.0Hz,2H),1.59(tt,J=8.1,6.9Hz,2H),1.38–1.22(m,6H),0.93–0.73(m,3H).

[0110] (4) Preparation of 6-hexyl-2-naphthol

[0111] In a 100 mL three-necked flask, 5 mmol of 6-bromo-2-naphthol and 0.5 mmol of [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride (PdCl2(dppf)) were added, followed by 50 mL of tetrahydrofuran. The system was cooled to 0 °C, and then hexyl magnesium bromide (C6H) was slowly added dropwise. 13 The reaction was quenched by adding 6.25 mmol of BrMg and refluxing the entire system at 65 °C for 4 hours, then cooled to room temperature and quenched by adding saturated ammonium chloride (5 mL). The mixture was extracted with ethyl acetate (20 mL × 3), and the organic phase was washed successively with saturated ammonium chloride and saturated sodium bicarbonate. The mixture was dried over anhydrous sodium sulfate and finally evaporated to dryness and passed through a silica gel column to give 6-hexyl-2-naphthol.

[0112] The structural confirmation data for this product are shown below:

[0113] Mass spectrometry: EI:M + 228.

[0114] 1H NMR spectrum: 1H NMR(400MHz,Chloroform-d)δ7.68(d,J=8.7Hz,1H),7.60(d,J=8.4Hz,1H),7.53(s,1H),7.30(s,1H),7.16–7.02(m,2H),4.13 (q,J=7.1Hz,1H),2.72(t,J=7.7Hz,2H),2.05(s,2H),1.66(dd,J=14.6,7.1Hz,2H),1.28(dd,J=16.0,8.8Hz,7H),0.89(s,4H).

[0115] (5) Preparation of 6-hexyl-2-trifluoromethanesulfonate-naphthalene

[0116] In a 50 mL three-necked flask, 2 mmol of 6-hexyl-2-naphthol, 3 mL of CH₂Cl₂, and 0.7 mL of triethylamine (TMA) were added. The system was cooled to -20 °C, and then 3 mmol of trifluoromethanesulfonic anhydride (Tf₂O) was slowly added dropwise. The mixture was stirred for 3 hours while maintaining the temperature, and then slowly brought to room temperature. 4 mL of CH₂Cl₂ was added, followed by crushed ice to quench the reaction. The mixture was extracted with CH₂Cl₂ (10 mL × 3), dried over anhydrous sodium sulfate, and then evaporated to dryness and passed through a silica gel column to obtain 6-hexyl-2-trifluoromethanesulfonic acid-naphthalene.

[0117] The structural confirmation data for this product are shown below:

[0118] Mass spectrometry: EI:M + 360

[0119] 1H NMR spectrum: 1 H NMR(400MHz,Chloroform-d)δ7.65(d,J=8.8Hz,1H),7.57(d,J=8.4Hz,1H),7.51(s,1H),7.26(d,J=8.2Hz,1H),7.08( s,1H),7.03(d,J=8.8Hz,1H),2.69(t,J=7.7Hz,2H),1.63(dd,J=14.4,7.0Hz,2H),1.30(s,6H),0.84(d,J=6.5Hz,3H).

[0120] (6) Preparation of 6-hexyl-2-naphthylborone

[0121] In a 50 mL three-necked flask, 6-hexylnaphthyl-2-yltrifluoromethanesulfonate (1.0 mmol, CAS: 2170221-76-6), pinacol diboronate (1.5 mmol, CAS: 73183-34-3), palladium acetate (0.05 mmol), 2-bicyclohexylphosphine-2',6'-dimethoxy-1,1'-diphenyl (S-Phos, 0.1 mmol), and potassium acetate (4 mmol) were added. The mixture was evacuated under argon gas three times, and then DMF (10 mL) was added under nitrogen protection. The mixture was refluxed at 80 °C for 24 h. The solvent was removed by rotary evaporation, and the mixture was extracted with water and CH2Cl2 sequentially. The organic phase was then washed with saturated NaCl solution, filtered, and the filtrate was filtered again. The filtrate was mixed with silica gel powder and passed through a column to obtain 6-hexyl-2-naphthylboronate.

[0122] The structural confirmation data for this product are shown below:

[0123] Mass spectrometry: EI:M + 338.

[0124] 1H NMR spectrum: 1 H NMR(400MHz,Chloroform-d)δ7.96(s,1H),7.83–7.65(m,3H),7.49(s,1H),2.62(t,J =8.0Hz,2H),1.90–1.51(m,2H),1.41–1.32(m,4H),1.24(s,12H),1.06–0.47(m,3H).

[0125] (7) Preparation of 2-hexyl-7-(6-hexylnaphth-2-yl)benzoselenophene (C6-BSBSN-C6)

[0126] In a 50 mL three-necked flask, 2-bromo-7-hexylbenzoselenene (1 mmol), 6-hexyl-2-naphthylborone (1.1 mmol), tetrakis(triphenylphosphine)palladium (0.05 mmol), and K₂CO₃ (4 mmol) were added sequentially. Then, toluene (16 mL), ethanol (4 mL), and water (4 mL) were added. The reaction mixture was heated and stirred at 90 °C for 24 h. The reaction system was filtered, and the residue was washed sequentially with anhydrous ethanol and dichloromethane to obtain a crude product. Sublimation purification yielded a white solid, namely C₆-BSBSN-C₆.

[0127] The structural confirmation data for this product are shown below:

[0128] Mass spectrometry: EI:M + 628.

[0129] 1H NMR spectrum: 1H NMR(400MHz,Chloroform-d)δ7.98(t,J=1.8Hz,1H),7.92–7.83(m,3H),7.66– 7.57(m,4H),7.54(dd,J=8.0,1.9Hz,1H),7.49(t,J=2.2Hz,1H),7.26(dd,J=8. 1,2.3Hz,1H),7.11(dd,J=7.4,2.3Hz,1H),2.62(t,J=8.0Hz,2H),2.55(t,J=8 .0Hz,2H),1.59(tt,J=8.0,6.9Hz,4H),1.37–1.22(m,12H),1.06–0.78(m,6H).

[0130] As can be seen from the above, the structure of this compound is correct.

[0131] The C6-BSBSN-C6 solution (solvent: dichloromethane, concentration: 10) was tested using a Jasco V-570 UV-Vis spectrometer. -5 The UV-Vis absorption spectra of the thin film (mol / L) and the thin film (30 nm thick, vacuum-deposited on a quartz substrate). For example... Figure 1 As shown, the molecule has strong absorption in the solar blind region (200-280nm), and the absorption wavelength of the thin film in the solar blind region is specifically 270nm.

[0132] The thermogravimetric temperature of C6-BSBSN-C6 material was tested using a Perkin Elmer TGA7 thermogravimetric analyzer. Figure 2 As shown, the molecule exhibits excellent stability, with a thermal weight loss temperature of around 398 degrees Celsius.

[0133] II. Fabrication and Performance Characterization of Solar Blind Zone Photodetectors Based on C6-BSBSN-C6 Molecules

[0134] according to Figure 3 The device structure diagram shown illustrates the fabrication of the device. OTS-modified Si / SiO2 was used as the substrate, where Si represents the gate voltage, and the OTS-modified SiO2 served as the insulating layer (500 nm). A 30 nm thick C6-BSBSN-C6 film was vacuum-deposited on the substrate as the active layer. Subsequently, a 30 nm thick gold layer was deposited on the film using a photomask as the source and drain electrodes. The channel length and width were 240 μm and 30 μm, respectively. This yielded a solar-blind zone photodetector based on the C6-BSBSN-C6 film.

[0135] Using a monochromatic LED light source (wavelength 270nm) equipped with a Keysight B1500 analyzer, incident light was focused from the light source and guided onto the device to test the optical performance of the photodetector based on C6-BSBSN-C6 thin film, obtaining transfer curves under different light intensities. Figure 4 As shown, the current in the light state increases significantly compared to the transition curve in the dark state. Before device testing, the incident light power intensity was calibrated using a power meter (PM100D). The time-dependent optical response curves of the device under different light intensities were also tested. Figure 5 As shown, the device can exhibit highly sensitive and fast switching behavior under light of different intensities.

[0136] The transfer curves of the C6-BSBSN-C6 photodetector under dark and sunlight conditions were also tested. Figure 6 As shown, the two curves almost overlap, indicating that the C6-BSBSN-C6 photodetector has no response under sunlight and therefore has good solar blind light selectivity.

[0137] The three key parameters of the C6-BSBSN-C6 photodetector were further characterized: photosensitiveness (P), photoresponsivity (R), and detectivity (D*). Figure 7 As shown, the values ​​of P, R, and D* reached 10. 6 10 3 and 10 15 This demonstrates the high sensitivity, high responsivity, and high detectivity of the C6-BSBSN-C6 photodetector.

[0138] Example 2 illustrates the preparation process of the BSBSA-C8 molecule, an asymmetric bis(selenophene)-benzo(selenophene)-benzene (BSBS) derivative with a single alkyl chain substitution, and the fabrication process of a solar-blind zone photodetector based on the BSBSA-C8 thin film.

[0139] The BSBSA-C8 molecule was prepared according to the synthetic route shown below:

[0140]

[0141] The specific steps are as follows:

[0142] (1) Preparation of 2-bromobenzoxenylbenzaselenophene

[0143] In a 50 mL three-necked flask, benzo[a]selenide (5 mmol) was dissolved in 30 mL of dichloromethane. Then, liquid bromine (0.23 mL, 4.5 mmol) was dissolved in 10 mL of dichloromethane and slowly added to the reaction mixture using a constant-pressure dropping funnel. The reaction was carried out at room temperature in the dark for 3 h. After the reaction was completed, methanol was added, and a precipitate formed. The precipitate was filtered, washed with anhydrous ethanol, and further recrystallized from chloroform / methanol to obtain 2-bromobenzo[a]selenide.

[0144] The structural confirmation data for this product are shown below:

[0145] Mass spectrometry: EI:M + 413.

[0146] 1H NMR spectrum: 1 H NMR(400MHz,Chloroform-d)δ7.92(d,J=2.1Hz,1H),7.85(dd,J=7.2,1.4Hz,1H),7.73(dd,J=7.3,1.8Hz,1H) ,7.66(d,J=7.7Hz,1H),7.52(dd,J=7.7,2.2Hz,1H),7.41(td,J=7.3,1.4Hz,1H),7.30(td,J=7.2,1.8Hz,1H).

[0147] (2) Preparation of 6-octylanthracene-2-yltrifluoromethanesulfonate

[0148] In a 100 mL three-necked flask, 2,6-bis(trifluoromethanesulfonate)anthracene (2.11 mmol, CAS: 594838-61-6), [1,1'-bis(diphenylphosphino)ferrocene]palladium dichloride ((PdCl2(dppf))) (0.065 mmol), and tert-butyl methyl ether (MTBE, 12 mL) were added. A 1 M octyl magnesium bromide tetrahydrofuran solution (C8H17BrMg, 1.05 mmol) was slowly added dropwise at 30 °C, and the mixture was refluxed for 3 h. Extraction was performed sequentially with water and ethyl acetate. The organic phase was filtered, and the filtrate was filtered through a column with silica gel to obtain 6-octylanthracene-2-yltrifluoromethanesulfonate.

[0149] The structural confirmation data for this product are shown below:

[0150] Mass spectrometry: EI:M + 438.

[0151] 1H NMR spectrum: 1H NMR(400MHz,Chloroform-d)δ8.40(d,J=8.8Hz,2H),8.05(d,J=9.2Hz,1H),7.94(d,J=8.7Hz,1H),7.88(s,1H),7.77(s,1H),7. 40(d,J=8.6Hz,1H),7.32(d,J=9.3Hz,1H),2.82(t,J=7.7Hz,2H),1.82–1.68(m,2H),1.46–1.26(m,8H),0.90(t,J=5.9Hz,3H).

[0152] (3) Preparation of 6-octylanthracene-2-ylboron ester

[0153] In a 50 mL three-necked flask, 1.0 mmol of 6-octylanthracene-2-yltrifluoromethanesulfonate, 1.5 mmol of pinacol diboronate, 0.05 mmol of palladium acetate, 0.1 mmol of s-phos, and 4 mmol of potassium acetate were added. The flask was evacuated under argon gas three times, and then 20 mL of DMF was added under nitrogen protection. The mixture was refluxed at 80 °C for 24 h. The solvent was removed by rotary evaporation, and the mixture was extracted with water and CH2Cl2 in sequence. The organic phase was then washed with saturated NaCl solution, filtered, and the filtrate was mixed with silica gel powder and passed through a column to obtain 6-octylanthracene-2-ylboronate.

[0154] The structural confirmation data for this product are shown below:

[0155] Mass spectrometry: EI:M + 416.

[0156] 1H NMR spectrum: 1 H NMR(400MHz,Chloroform-d)δ8.39(dt,J=2.5,1.3Hz,1H),8.33(t,J=2.2Hz,1H), 8.05(t,J=2.0Hz,1H),8.01(dd,J=8.0,1.8Hz,1H),7.82(dd,J=7.5,2.2Hz,1H),7 .74(dd,J=7.5,1.9Hz,1H),7.47(t,J=2.2Hz,1H),7.24(dd,J=8.1,2.2Hz,1H),2. 62(t,J=8.0Hz,2H),1.57(s,2H),1.35–1.27(m,10H),1.24(s,12H),0.89(s,3H).

[0157] (4) Preparation of 2-(6-octylanthracene-2-yl)benzoselenophene benzoselenophene (BSBSA-C8)

[0158] In a 100 mL three-necked flask, 2-bromobenzoselenene (3 mmol), 6-octylanthracene-2-ylboron ester (3.1 mmol), tetrakis(triphenylphosphine)palladium (0.15 mmol), and K₂CO₃ (12 mmol) were added sequentially. Then, toluene (48 mL), ethanol (12 mL), and water (12 mL) were added. The reaction mixture was heated and stirred at 90 °C for 24 h. The reaction system was filtered, and the residue was washed sequentially with anhydrous ethanol and dichloromethane to obtain a crude product. Sublimation purification yielded a yellow solid, which was BSBSA-C8.

[0159] The structural confirmation data for this product are shown below:

[0160] Mass spectrometry: EI:M + 624.

[0161] 1H NMR spectrum: 1 H NMR(400MHz,Chloroform-d)δ7.83(d,J=9.0Hz,1H),7.78(d,J=8.4Hz,1H),7.70(d,J=2.5Hz,1H),7.64(s,1H),7.43(d,J=8.4 Hz,1H),7.33(dd,J=9.0,2.5Hz,1H),2.77(t,J=7.7Hz,2H),1.70(q,J=7.3Hz,2H),1.47–1.11(m,10H),0.87(t,J=6.7Hz,3H).

[0162] As can be seen from the above, the structure of this compound is correct.

[0163] The BSBSA-C8 solution (solvent: dichloromethane, concentration: 10) was tested. -5 The UV-Vis absorption spectra of the mol / L thin film (30 nm thick, vacuum-deposited on a quartz substrate) were measured using the same method as in Example 1. Figure 8 As shown, the molecule has strong absorption in the solar blind region (200-280nm), and the absorption wavelength of the thin film in the solar blind region is specifically 264nm.

[0164] The thermogravimetric temperature of the BSBSA-C8 material was tested using the same method as in Example 1. Figure 9 As shown, the molecule exhibits excellent stability, with a thermal weight loss temperature of around 384 degrees Celsius.

[0165] (5) Fabrication and performance characterization of solar-blind zone photodetectors based on BSBSA-C8 molecules:

[0166] according to Figure 3The device structure diagram shown is used for device fabrication, where the BSBSA-C8 thin film is used as the active layer. The fabrication process is similar to that in Example 1, resulting in a solar blind zone photodetector based on the BSBSA-C8 thin film.

[0167] The optical performance of the solar-blind zone photodetector based on BSBSA-C8 thin film was tested, and transfer curves under different light intensities were obtained. The selected LED light source had a wavelength of 265 nm, and the testing method was the same as in Example 1. Figure 10 As shown, the current in the light state is significantly increased compared to the transfer curve in the dark state.

[0168] The transfer curves of the BSBSA-C8 photodetector under dark and sunlight conditions were also tested. Figure 11 As shown, the two curves almost overlap, indicating that the BSBSA-C8 photodetector has no response under sunlight and therefore has good solar blind light selectivity.

[0169] The three key parameters of the BSBSA-C8 photodetector were further characterized: photosensitiveness (P), photoresponsivity (R), and detectivity (D*). Figure 12 As shown, the values ​​of P, R, and D* reached 10. 5 10 3 and 10 14 This demonstrates the high sensitivity, high responsivity, and high detectivity of the BSBSA-C8 photodetector.

[0170] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including modifications made using conventional techniques known in the art that depart from the scope disclosed herein.

Claims

1. An asymmetric benzo[a]selenophene benzo[a]selenophene derivative, the structural formula of which is shown in Formula I: 。 2. The method for preparing the asymmetric benzo[a]selenphene benzo[a]selenphene benzene derivative according to claim 1, comprising the following steps: (1) The compound shown in Formula II was reacted with liquid bromine in a solvent to obtain the compound shown in Formula III; In Equations II and III, R represents the n-hexyl group; (2) Under an inert atmosphere, the compound shown in Formula IV was reacted with pinacol diboronic acid in a solvent in the presence of a catalyst to obtain the compound shown in Formula V. (3) Under an inert atmosphere, the compound shown in Formula III and the compound shown in Formula V are reacted in a solvent with the action of a target catalyst and carbonate to obtain the asymmetric benzo[selen]phene benzo[selen]phene derivative shown in Formula I.

3. The method of claim 2, wherein: In step (1), the molar ratio of the compound shown in formula II to liquid bromine is 1:(0.7~1). In step (1), the reaction temperature is 20~25℃ and the time is 1~5h; In step (1), the solvent is dichloromethane or N,N-dimethylformamide.

4. The production method according to claim 2 or 3, characterized by: In step (2), the molar ratio of the compound shown in formula IV to the pinacol diboronic acid ester is 1:(1~3). In step (2), the catalyst is 2-dicyclohexylphosphine-2',6'-dimethoxy-1,1'-diphenyl, palladium catalyst and potassium acetate, wherein the molar ratio of the compound shown in Formula IV, 2-dicyclohexylphosphine-2',6'-dimethoxy-1,1'-diphenyl, palladium catalyst and potassium acetate is 1:(0.1~0.2):(0.04~0.1):(2~5), and the target catalyst is palladium acetate or 1,1'-bis(diphenylphosphino)ferrocene)palladium dichloride; In step (2), the reaction temperature is 70~90℃ and the time is 24~48h; In step (2), the solvent is tetrahydrofuran or N,N-dimethylformamide.

5. The method of claim 2 or 3, wherein: In step (3), the molar ratio of the compound shown in formula III to the compound shown in formula V is 1:(1~1.3). In step (3), the molar ratio of the compound shown in Formula III, the target catalyst, and the carbonate is 1:(0.03~0.06):(4~8). In step (3), the target catalyst is at least one of tetratriphenylphosphine palladium and 1,1'-bis(diphenylphosphine)ferrocene)palladium dichloride; In step (3), the carbonate is at least one of potassium carbonate, sodium carbonate, and cesium carbonate; In step (3), the reaction temperature is 80~90℃ and the time is 12~24h; In step (3), the solvent is composed of toluene, ethanol and water, and the volume ratio of toluene, ethanol and water is (2~6):1:

1.

6. The application of the asymmetric benzo[a]selenphene benzo[a]selenphene derivative of claim 1 in solar blind zone photodetection or in the preparation of solar blind zone photodetectors, wherein the solar blind zone is deep ultraviolet light with a wavelength of 200~280 nm.

7. A solar blind photodetector comprising an organic semiconductor active layer, characterized in that: The organic semiconductor active layer comprises the asymmetric benzo[a]selenide-benzo[a]selenide-benzo[a]benzene derivative as described in claim 1.

8. The solar blind photodetector of claim 7, wherein: The solar blind zone photodetector has a bottom-gate top-contact configuration, including, from bottom to top, a gate electrode layer, a gate insulating layer, an organic semiconductor active layer, and source and drain electrode layers; The gate electrode is made of Si; The gate insulating layer is a silicon oxide layer or a composite insulating layer with a silicon oxide-modified self-assembled layer, and the general formula of the silicon oxide self-assembled layer is shown in Formula VI: In formula VI, R1 is any one of C1-C24 alkyl, C1-C24 cycloalkyl, C1-C24 perfluoroalkyl, and phenyl. The thickness of the organic semiconductor active layer is 30~50 nm; The electrodes in the source and drain electrode layers are made of gold, silver, or platinum.

9. The method for fabricating the solar blind zone photodetector according to claim 8, comprising the following steps: (1) The gate insulating layer is prepared on the gate electrode layer; (2) The organic semiconductor active layer is prepared on the gate insulating layer by means of spin coating, drop casting, vapor deposition, blade coating or printing; (3) The source and drain electrode layers are prepared on the organic semiconductor active layer by means of transferring metal electrodes or evaporating metal to obtain the solar blind zone photodetector.

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