Carbazole photosensitive dye containing triple bonds as well as synthesis method and application of carbazole photosensitive dye

Abstract

The invention belongs to the technical field of dye-sensitized solar cells, and relates to a three-bond-containing carbazole photosensitive dye and a synthesis method and application thereof. A strong electron withdrawing group carbon-carbon triple bond is introduced into an acceptor part, so that the capture capability of the dye on photoelectrons is greatly enhanced, the spectral response range of the dye is widened, the photocurrent density of a device formed by the dye is improved, and the performance of the device is improved. Meanwhile, introduction of carbon-carbon triple bonds can effectively expand a pi conjugated system, the molecular structure is optimized, and the photoelectric conversion efficiency reaches 4.2%. In order to further improve the photoelectric conversion efficiency, the dye AJ502 is co-sensitized, and the final photoelectric conversion efficiency of the cell reaches 5.9%.

Description

Technical Field

[0001] This invention belongs to the field of dye-sensitized solar cell technology, and relates to a carbazole-based photosensitive dye containing a triple bond, its synthesis method, and its application. Background Technology

[0002] Dye-sensitized solar cells, as a third-generation solar cell, have received widespread research and attention from scientists. Dye-sensitized solar cells possess advantages such as simple fabrication processes, diverse colors, environmental friendliness, and good stability. The photosensitizer, as the core component of dye-sensitized solar cells, directly affects the device's utilization of sunlight, thus influencing its photoelectric performance. Among various photosensitizers, pure organic dyes have high molar extinction coefficients, flexible and varied molecular structures, simple synthesis, considerable yields, wide availability of raw materials, and controllable costs, making them suitable for large-scale industrial production. Therefore, pure organic dyes, as alternatives to metal complex dyes, have attracted considerable attention from researchers.

[0003] While the structures of purely organic dyes are theoretically diverse, current design strategies primarily utilize intramolecular charge transfer (ICT) D-π-A structures and chromophore-derived structures. D stands for electron donor, with common donors including triphenylamine, carbazole, phenothiazine, and tetrahydroquinoline. It mainly affects the HOMO energy level of the dye; enhancing the donor's electron-donating properties effectively increases the HOMO energy level, narrowing the dye's band gap and broadening its absorption spectrum. Commonly used π-bridging groups include alkenynes, fused rings, and heterocycles (such as thiophene, furan, and pyrrole). A stands for electron acceptor, primarily affecting the LUMO energy level of the dye. Enhancing the acceptor's electron-withdrawing properties lowers the LUMO energy level, narrowing the dye's band gap and thus broadening its spectral response range.

[0004] Different electron acceptors have different electron injection capabilities, which in turn affect the optical performance of devices. By designing suitable acceptor structures, the light absorption range of photosensitizers can be broadened, electron injection efficiency and stability can be improved, thereby further enhancing the photoelectric conversion efficiency of DSSCs. Summary of the Invention

[0005] The purpose of this invention is to provide a carbazole-based photosensitive dye containing a triple bond, its synthesis method, and its application. By introducing a strong electron-withdrawing carbon-carbon triple bond group into the acceptor portion, the dye's ability to capture photoelectrons is greatly enhanced, its spectral response range is broadened, thereby increasing the photocurrent density of the device and improving the device's performance. At the same time, the introduction of the carbon-carbon triple bond can effectively expand the π-conjugated system, optimize the molecular structure, and thus improve the photoelectric conversion efficiency.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: This invention provides a carbazole compound containing a triple bond, the molecular structural formula of which is: .

[0007] Another aspect of the present invention provides a method for preparing the above-mentioned carbazole compound containing a triple bond, comprising the following steps: (1) Using 4,7-bis(5-bromo-4-hexylthiophene-2-)-2,1,3-benzothiadiazole as a π-bridge and ethyl 4-ethynylbenzoate as an acceptor, 4,7-bis(5-bromo-4-hexylthiophene-2-)-2,1,3-benzothiadiazole and ethyl 4-ethynylbenzoate were subjected to a Sonogashira coupling reaction. After the reaction was completed, the reaction solution was extracted with dichloromethane. The resulting concentrate was dissolved in the eluent and then separated and purified by column chromatography with silica gel. The eluent was collected and the elution was removed by evaporation to obtain compound I. (2) Compound II was subjected to a Suzuki coupling reaction with 4-bromo-N,N-bis[4-(2-ethylhexyloxy)phenyl]-aniline, followed by a Miyaura borylation reaction to obtain compound III; (3) Using compound III as a donor, compound I and compound III were subjected to a Suzuki coupling reaction, followed by hydrolysis to obtain the target product; The molecular structural formula of compound I is:

[0008] The molecular structural formula of compound II is:

[0009] The molecular structural formula of compound III is: .

[0010] Furthermore, in step (1), the reaction time is 12-20 h, preferably 16 h.

[0011] Furthermore, in step (1), the reaction is carried out under nitrogen protection.

[0012] Further, in step (1), the reaction solvent is a mixture of toluene, dichloromethane, chloroform, tetrahydrofuran or 1,4-dioxane and water, with a volume ratio of toluene, dichloromethane, chloroform or tetrahydrofuran to water of 5:1 and a volume ratio of 1,4-dioxane to water of 6:1, preferably a mixture of toluene and water.

[0013] Furthermore, in step (1), the molar ratio of π bridge to receptor is 1:0.6-1, preferably 1:0.8.

[0014] Furthermore, in step (3), the molar ratio of compound I to the donor is 1:1.5.

[0015] Furthermore, in step (1), the reaction temperature is 70-95℃, preferably 80℃.

[0016] Further, in step (1), the eluent is a mixed solvent composed of petroleum ether and dichloromethane, wherein the volume ratio of petroleum ether to dichloromethane is 2-4:1, preferably 3:1.

[0017] A third aspect of the present invention provides the application of the above-mentioned carbazole compounds as photosensitizers in dye-sensitized solar cells.

[0018] The fourth aspect of this invention provides the application of the above-mentioned carbazole compound together with dye AJ502 as a photosensitizer in dye-sensitized solar cells.

[0019] The beneficial effects of this invention are as follows: This invention provides a carbazole-based dye photosensitizer containing a triple bond. By introducing a strong electron-withdrawing carbon-carbon triple bond group into the acceptor portion, the dye's ability to capture photoelectrons is greatly enhanced, broadening its spectral response range and thus increasing the photocurrent density of the device it forms, thereby improving device performance. Simultaneously, the introduction of the carbon-carbon triple bond effectively expands the π-conjugated system, optimizing the molecular structure and achieving a photoelectric conversion efficiency of 4.2%.

[0020] To further improve its photoelectric conversion efficiency, its dye AJ502 was co-sensitized, and the final photoelectric conversion efficiency of the battery reached 5.9%. Attached Figure Description

[0021] Figure 1 The images show the UV-Vis absorption spectra of dyes SG1 and SG2 in dichloromethane and on a TiO2 film. (a) shows the absorption spectra in dichloromethane, and (b) shows the absorption spectra on a TiO2 film. Figure 2 The figures show the cyclic voltammetry curves and HOMO and LUMO energy level diagrams for dyes SG1 and SG2. (a) is the cyclic voltammetry curve, and (b) is the HOMO and LUMO energy level diagram. Figure 3 The HOMO and LUMO electron cloud distributions of dyes SG1 and SG2; Figure 4 The images show adsorption test results for dyes SG1 and SG2. (a) shows SG1, and (b) shows SG2. Figure 5 The IPCE spectrum and integrated current curve of the battery device sensitized by dyes SG1 and SG2, and the JV curve tested under standard conditions are shown in (a) and (b). Figure 6The electrochemical impedance spectra of the battery devices sensitized by dyes SG1 and SG2 are shown. (a) is the Nyquist plot and (b) is the Bode plot. Figure 7 The UV-Vis absorption spectra of dyes SG1 and AJ502 in dichloromethane are shown. Figure 8 The IPCE spectrum and integrated current curves of the single-sensitized SG1, AJ502 and their co-sensitized battery devices, and the JV curves tested under standard conditions are shown in (a) and (b). Detailed Implementation

[0022] The present invention will be described in detail with reference to specific examples to enable those skilled in the art to better understand the invention. However, the invention is not limited thereto.

[0023] Unless otherwise specified, the materials used in the embodiments of the present invention can be obtained commercially or prepared according to conventional methods known to those skilled in the art.

[0024] Example 1 The synthetic route for the photosensitive dye SG1 is as follows: .

[0025] The specific steps are as follows: Step 1: Compound 1 (6 g, 9 mmol) and ethyl 4-ethynylbenzoate (1.4 g, 8.2 mmol) were added to a 250 mL two-necked flask, evacuated, and purged with nitrogen three times. 50 mL of toluene solvent was added, and the mixture was bubbled with nitrogen for 15 minutes. Then, 8 mL of triethylamine solution (4 M, 8 mmol), PdCl2(PPh3)3 (1.2 g, 1.2 mmol), and CuI (240 mg, 1.2 mmol) were added. The mixture was heated to reflux for 16 hours, cooled to room temperature, and transferred to a 500 mL pear-shaped separatory funnel. The organic phase was extracted with dichloromethane to obtain the crude product. The crude product was then separated by chromatography using dichloromethane / petroleum ether (3:1, v / v) as the developing solvent to obtain a red solid compound 2 (4.8 g, 74% yield). The characterization data are as follows: 1¹H NMR (500MHz, CDCl₃) δ 8.04 (d, J=8.5Hz, 2H), 7.81 (d, 2H), 7.78 (s, 1H), 7.57 (d, J=8.2Hz, 1H), 7.12 (s, 1H), 4.40 (q, J=7.1Hz, 2H), 2.83 (t, 4H), 2.67–2.59 (m, 4H), 1.83–1.32 (m, 12H), 1.30 (t, 3H), 0.90–0.82 (t, 6H). MS (MALDI-TOF, m / z) Theoretical calculated value C 37 H 39 BrN2O2S3[M] + : 718.1; Measured value: 718.2.

[0026] Step 2: Compound 3 (1.26 g, 1.0 mmol), compound 2 (1.17 g, 1.5 mmol), K₂CO₃ (207 mg, 1.5 mmol), and Pd(PPh₃)₄ (200 mg, 0.2 mmol) were added to a 50 mL two-necked flask. The flask was evacuated three times with nitrogen. A mixture of 30 mL THF and 6 mL water was added, and the mixture was bubbled with nitrogen for 15 minutes. The reaction mixture was heated to 80 °C and refluxed for 12 h. After cooling to room temperature, the mixture was washed with water. The reaction solution was transferred to a 500 mL pear-shaped separatory funnel, and the organic phase was extracted with dichloromethane. The solution was evaporated to dryness to obtain the crude product. The crude product was subjected to chromatographic separation using dichloromethane / petroleum ether (3:1, v / v) as the developing solvent, yielding a red solid. The obtained compound (355 mg, 0.2 mmol) and KOH (504 mg, 9 mmol) were added to a 50 mL two-necked round-bottom flask, and 30 mL of THF / H2O (5:1, v / v) solvent was added. The mixture was heated under reflux for 24 h to carry out hydrolysis. After the reaction was completed, the mixture was cooled to room temperature, and a large amount of water was added to quench the reaction. Then, 2 M hydrochloric acid was added to neutralize the mixture to pH 1-3. The reaction solution was then transferred to a 500 mL pear-shaped separatory funnel, and the organic phase was extracted with dichloromethane. After evaporation to dryness, the crude product was obtained. The crude product was separated by chromatography using dichloromethane / methanol (20:1, v / v) as the developing solvent to obtain a red solid compound SG1 (278 mg of product, 80% yield).

[0027] The characterization data are as follows: 1¹H NMR (500 MHz, CDCl₃) δ 0.97–0.87 (m, 30H), 1.32–1.22 (m, 38H), 1.58–1.49 (m, 12H), 1.8 (t, 2H), 2.71 (t, 4H), 3.387–3.65 (d, 8H), 7.41–6.75 (m, 14H), 7.55–8.52 (m, 20H). MS (MALDI-TOF, m / z) Theoretical calculated C 113 H 129 N5O4S4[M] + : 1747.9; Measured value: 1747.9.

[0028] The synthesis method of compound 3 includes the following steps: (1) Compound II was synthesized according to the method of Thiophene-fused carbazole derivative dyes for high-performance dye-sensitized solar cells; The molecular structural formula of compound II is:

[0029] (2) Compound II (2.0 g, 2.61 mmol), 4-bromo-N,N-bis[4-(2-ethylhexyloxy)phenyl]-aniline (1.59 g, 2.75 mmol), K2CO3 (1.80 g, 13.05 mmol), H2O (7 mL), and 1,4-dioxane (40 mL) were sequentially added to a 100 mL two-necked flask. Nitrogen gas was bubbled for 15 min to remove oxygen from the solvent. Then, catalyst Pd(PPh3)4 (0.15 g, 0.13 mmol) was added. The mixture was stirred under nitrogen protection and heated to 80 °C for 12 minutes. After cooling to room temperature, the extract was poured into saturated brine and extracted three times with DCM. The extract was then poured into a separatory funnel and washed five times with saturated brine to remove residual 1,4-dioxane. The filtrate was collected and dried with Na2SO4. Impurities were removed by filtration, and the filtrate was collected and evaporated by rotary evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain the intermediate. The intermediate (6 g, 5.22 mmol) and 70 mL of dry THF were added to a 250 mL two-necked flask and dissolved and stirred under nitrogen protection. The reaction solution was placed in a Dewar flask and cooled with liquid nitrogen. The ethanol was cooled to -78 °C and kept at this temperature for 10 min. Under nitrogen protection, n-butyllithium (3.68 mL, 5.74 mmol) was pipetted into the rubber stopper of the reaction flask and suspended above the reaction solution. The solution was added dropwise, maintaining a low temperature throughout the process. After the addition was complete, the temperature was kept at this level for 1 h. Then, isopropoxide borate (1.1 g, 5.74 mmol) was added with a needle and reacted for 5 h. h; The reaction solution was poured into saturated saline solution and extracted three times with DCM. The filtrate was collected and dried with Na2SO4. Impurities were removed by filtration. The filtrate was collected and evaporated by rotary evaporation to obtain the crude product. The crude product was purified by silica gel column chromatography to obtain compound 3.

[0030] Comparative Example 1 The photosensitive dye SG2, which does not contain a triple bond in the acceptor, was synthesized according to the synthesis method of Example 1. The synthesis route is as follows: .

[0031] The specific steps are as follows: Step 1: Compound 1 (6.26 g, 10 mmol), 3-methylthiophene borate (2.1 g, 8 mmol), and K2CO3 (2.76 g, 20 mmol) were added to a 250 mL two-necked flask. The flask was evacuated and purged with nitrogen three times. 60 mL of 1,4-dioxane and 10 mL of water were added. The mixture was bubbled with nitrogen for 15 minutes. Pd(PPh3)4 (588 mg, 0.5 mmol) catalyst was added, and the mixture was heated under reflux for 16 hours. After cooling to room temperature, the mixture was transferred to a 500 mL pear-shaped separatory funnel. The organic phase was extracted with dichloromethane to obtain the crude product. The crude product was then separated by chromatography using dichloromethane / petroleum ether (3:1, v / v) as the developing solvent to obtain a red solid compound 4 (4.6 g, yield 67%). The characterization data are as follows: 1 ¹H NMR (500 MHz, CDCl₃) δ 8.04 (d, J = 8.5 Hz, 2H), 7.81 (d, 2H), 7.78 (s, 1H), 7.57 (d, J = 8.2 Hz, 1H), 7.12 (s, 1H), 4.40 (q, J = 7.1 Hz, 2H), 2.83 (t, 4H), 2.67–2.59 (m, 4H), 1.83–1.32 (m, 12H), 1.30 (t, 3H), 0.90–0.82 (t, 6H). MS (MALDI-TOF, m / z) Theoretical calculated C 34 H 37 BrN2O2S3[M] + :680.1; Measured value:680.2.

[0032] Step 2: Compound 3 (1.26 g, 1.0 mmol), compound 4 (1.02 g, 1.5 mmol), K₂CO₃ (207 mg, 1.5 mmol), and Pd(PPh₃)₄ (200 mg, 0.2 mmol) were added to a 50 mL two-necked flask. The flask was evacuated three times with nitrogen. A mixture of 30 mL THF and 6 mL water was added, and the mixture was bubbled with nitrogen for 15 minutes. The reaction mixture was heated to 80 °C and refluxed for 12 h. After cooling to room temperature, the mixture was washed with water. The reaction solution was transferred to a 500 mL pear-shaped separatory funnel, and the organic phase was extracted with dichloromethane. The solution was evaporated to dryness to obtain the crude product. The crude product was subjected to chromatographic separation using dichloromethane / petroleum ether (3:1, v / v) as the developing solvent to obtain a red solid. The compound was obtained by adding a portion of the compound (347 mg, 0.2 mmol) and KOH (504 mg, 9 mmol) to a 50 mL two-necked round-bottom flask. 30 mL of THF / H2O (5:1, v / v) solvent was added, and the mixture was heated under reflux for 24 h to carry out hydrolysis. After the reaction was completed, the mixture was cooled to room temperature, and a large amount of water was added to quench the reaction. Then, 2 M hydrochloric acid was added to neutralize the mixture to pH 1-3. The reaction solution was then transferred to a 500 mL pear-shaped separatory funnel, and the organic phase was extracted with dichloromethane. After evaporation to dryness, the crude product was obtained. The crude product was separated by chromatography using dichloromethane / methanol (20:1, v / v) as the developing solvent to obtain a red solid compound SG2 (295 mg of product, yield 85%).

[0033] The characterization data are as follows: 1 ¹H NMR (500 MHz, CDCl₃) δ 7.55–8.52 (m, 20H), 7.41–6.75 (m, 14H), 3.3.87–3.65 (d, 8H), 2.71 (t, 4H), 1.8 (t, 2H), 1.58–1.49 (m, 12H), 1.32–1.22 (m, 38H), 0.97–0.87 (m, 30H). MS (MALDI-TOF, m / z) Theoretical calculated C 111 H 129 N5O4S4[M] + :1723.89; Measured value:1723.98.

[0034] Test Example 1 The UV-Vis absorption spectra of the two photosensitive dyes SG1 and SG2 obtained in Example 1 and Comparative Example 1 were measured on dichloromethane and TiO2 films, respectively. Figure 1The results show that the maximum absorption wavelengths of SG1 and SG2 in dichloromethane are 505 nm and 499 nm, respectively, while the maximum absorption wavelengths in the UV-Vis absorption spectra of the TiO2 film are 509 nm and 505 nm. The corresponding molar extinction coefficients are 22900 mol·L⁻¹. -1 cm -1 and 20000 mol·L -1 cm -1 There are two redshift phenomena: first, dyes adsorbed on the TiO2 film show a redshift compared to those dissolved in dichloromethane; second, dyes with introduced triple bonds exhibit a redshift compared to those without. The former indicates that dye adsorption on the TiO2 film is not simple adsorption, but rather that the anchoring group forms a chemical bond with the Ti atoms of TiO2, resulting in less energy required for the dye to transition from the ground state to the excited state after adsorption, making the dye easier to excite. The latter demonstrates that the introduction of triple bonds can broaden the spectral response range, thereby improving the light-harvesting ability. This is because the carbon-carbon triple bond is a strong electron-withdrawing group, which enhances the electron-withdrawing ability of the acceptor portion, and the triple bond can effectively expand the π-conjugated system of the dye, optimizing the molecular structure.

[0035] Test Example 2 To obtain the HOMO and LUMO energy levels of dyes SG1 and SG2, and thus determine whether the dyes can be cyclically regenerated in dye-sensitized solar cells, cyclic voltammetry tests were performed on dyes SG1 and SG2. Figure 2 Calculations show that the HOMO energy levels of dyes SG1 and SG2 are 1.0 V and 1.14 V, respectively. These are higher than those of [Co(bpy)3]. 2+ / 3+ The energy levels are corrected, allowing electrons to be transferred to the oxidized dye state, thus regenerating it. The LUMO energy levels of dyes SG1 and SG2 are -1.01 V and -0.83 V, respectively, both more negative than the conduction band energy level of TiO2. This indicates that the dyes have sufficient driving force to inject electrons into TiO2.

[0036] Test Example 3 Density functional calculations were performed on the two photosensitive dyes SG1 and SG2 obtained in Example 1 and Comparative Example 1, respectively. Figure 3 Clearly, there is significant electron separation between the HOMO and LUMO energy levels of both dyes. This indicates that after the dyes are photoexcited, they can effectively separate electrons, thereby enabling efficient electron migration within the molecular energy and successfully injecting electrons into the semiconductor TiO2.

[0037] Test Example 4 The adsorption capacity of the two photosensitive dyes SG1 and SG2 obtained in Example 1 and Comparative Example 1 was tested. The specific steps are as follows: SG1 and SG2 were dissolved in dichloromethane to prepare a solution with a concentration of 1×10⁻⁶. -4 M dye mother liquor.

[0038] 12 g of SG1 dye mother liquor was divided into three equal portions, labeled as solution 1, 2, and 3. FTO with a 6 μm thick TiO2 film and blank FTO of the same size were immersed in solutions 1 and 2, respectively, and allowed to stand for 12 h. The FTO in solution 1 was removed and thoroughly washed with dichloromethane to remove weakly adsorbed dye from the surface. The washing solution and mother liquor were combined to a total mass of 5 g. The blank FTO glass in solution 2 underwent the same treatment, and 1 g of dichloromethane was added to bring the total mass to 5 g. In solution 3, 1 g of dichloromethane was added directly. Finally, 3 g of dichloromethane was added to each solution to ensure complete dye dissolution. The UV-Vis absorption spectra of the three solutions were then measured. The SG2 adsorption capacity was tested using the same method, and the adsorption capacity test results are shown below. Figure 4 As shown in the figure, A1, A2, and A3 are the absorbances of the final test solutions 1, 2, and 3 at the same wavelength, respectively. It can be seen that the adsorption amount of dye SG1 is significantly greater than that of SG2.

[0039] Application Example 1 The dyes obtained in Example 1 and Comparative Example 1 were used to assemble devices, and the steps are as follows: (1) Cleaning of FTO substrate First, gently wipe the conductive surface with a cotton ball soaked in dish soap to remove large dust particles. Then, ultrasonically clean it for 15 minutes in dish soap, ethanol, and acetone solutions respectively. After each step, rinse thoroughly with deionized water. Then, ultrasonically clean the substrate in deionized water for 5 minutes. Repeat the cycle cleaning three times to thoroughly remove ion residues. Dry it with a hair dryer on cool air. Finally, treat it with a plasma cleaner for 3 minutes and place it in a clean glass petri dish for later use. (2) Preparation of TiO2 dense layer First, prepare a TiCl4 precursor solution. Cool the solution to -25°C in a Dewar flask using liquid nitrogen and anhydrous ethanol. Add 100 mL of deionized water to a 250 mL round-bottom flask. Slowly add 55 mL of analytical grade TiCl4 dropwise to the vigorously stirred deionized water over approximately 2 hours. Finally, dilute the solution to a 250 mL volumetric flask to obtain a 2 mol / L TiCl4 aqueous solution. To prevent hydrolysis of TiCl4, store the solution in a refrigerator for later use. When needed, take 2 mL of the solution and dilute it to 40 mmol / L with 98 mL of deionized water. Immerse the cleaned FTO substrate with the conductive side facing up in the solution and place it in a 70°C oven for hydrothermal reaction for 30 minutes. Rinse the substrate with deionized water and ethanol to remove residues. After drying with a hairdryer, transfer the substrate to a muffle furnace and use a programmed temperature control (linearly increase the temperature to 500°C over 3 hours, hold for 1 hour, and then allow it to cool naturally) to complete the phase transformation and form a dense TiO2 layer. (3) Preparation of mesoporous layer and scattering layer First, adjust the printing part of the screen to align with the slot of the handprinting table, fix the screen printing plate on the handprinting table, wipe the screen with a lint-free cloth and anhydrous ethanol, and then dry it with a hair dryer; use a clean glass rod to dip the diluted 18-NRT paste on the non-screened part of the screen, and use a squeegee to spread the paste evenly in the micropores with screen printing (4 mm × 4 mm squares); place the FTO treated in step (2) with the conductive side facing up in the slot of the handprinting table, align it with the screen printed part of the screen printing plate, and then use a squeegee to spread it. Under the pressure of the squeegee, the paste is spread through the screen printing mesh onto the FTO; place the FTO in an ethanol vapor box for 1 minute to flow horizontally; then place it in a 125°C forced-air drying oven for 5 minutes to dry, and then cool it to room temperature; repeat the above steps three times to obtain a mesoporous TiO2 film with a thickness of about 6 μm. After cleaning the screen, the slurry was replaced with TPP-200, and the above steps were repeated once more to obtain a scattering layer with a thickness of approximately 3 μm. Finally, the layer was placed in a muffle furnace, linearly heated to 500℃ over 3 hours, held for 1 hour, and then allowed to cool naturally. A dense TiO2 layer was then formed on the film surface again via a TiCl4 hydrothermal reaction, and sintered again following the steps described above. (4) Preparation of dye bath and sensitization of film Compound SG1 obtained in Example 1 and compound SG2 obtained in Example 2 were dissolved separately in ultra-dry DCM solvent to prepare a concentration of 1×10⁻⁶. -4 The solvent of M; (5) Sensitization of TiO2 thin film Cut the FTO substrate prepared in step (3) into a 1 cm × 2 cm rectangle, place it flat on the bottom of a weighing bottle with the conductive side facing up, add the solution prepared in step (4) into the bottle, seal the bottle mouth with PTFE tape and sealing film, wrap the bottle body with aluminum foil, maintain the sensitization temperature at 20±2℃, and let it stand stably in the dark for 12 h for sensitization. After taking it out, rinse off the unadsorbed dye on the surface with ultra-dry dichloromethane, and dry it with nitrogen or a hair dryer with cold air for later use. (6) Preparation of electrolyte 0.25 M Co(bpy)3(B(CN)4)2, 0.05 M Co(bpy)3(B(CN)4)3, 0.10 M LiClO4 and 0.80 M TBP in acetonitrile solution; (7) Device packaging Place the sarin membrane on the conductive surface of the photoanode, ensuring the photosensitive area is completely exposed within the grid window. The conductive surface of the perforated platinum counter electrode faces the conductive surface of the photoanode, with the platinum-plated active area and the pre-drilled holes within the grid area. Use a hot press at 125°C and 0.2 MPa for 25 seconds to form a sealed cavity between the photoanode and counter electrode. Drop electrolyte onto the pre-drilled hole on the counter electrode. After evacuating the cavity using a vacuum device, quickly connect it to the atmosphere. Driven by the pressure difference, the electrolyte is drawn into the cavity. Once filled with electrolyte, cover the hole with the sarin membrane and a glass slide, and hot press again to complete the battery encapsulation. Plate the conductive areas at both ends of the battery with indium using a constant-temperature soldering station for testing.

[0040] JV testing was performed under simulated sunlight at AM 1.5G, and IPCE testing was conducted on the device after silicon cell calibration. The results are as follows: Figure 5 As shown, the data for the obtained sensitized devices are as follows: SG1 sensitized device, open-circuit voltage V OC =0.76V, short circuit voltage J SC =7.75mA cm -2 The fill factor FF = 71.69% and PCE = 4.2%. The data for the SG2 sensitized device are: V OC =0.81V, J SC =6.76mA cm -2 With FF=73.24% and PCE=4.1%, the introduction of triple bonds significantly improves photocurrent density and slightly improves photoelectric conversion efficiency.

[0041] Electrochemical impedance spectroscopy was performed on the dye-sensitized devices obtained in Example 1 and Comparative Example 1, and the results are as follows: Figure 6 As shown.

[0042] Application Example 2 The compound obtained in Example 1 was co-sensitized using dye AJ502 (prepared according to the method of Supramolecular Co-adsorption on TiO2 to enhance the efficiency of dye-sensitized solar cells), the structure of which is shown in the formula:

[0043] The compound obtained in Example 1 and compound AJ502 were subjected to UV-Vis absorption spectroscopy tests, and the results are as follows: Figure 7 The maximum visible absorption wavelength of SG1 is around 500 nm, while that of AJ502 is around 600 nm. Since their absorption wavelengths are complementary, blending them together and adsorbing them onto a TiO2 film will broaden the spectral response range, meeting the requirements for dye co-sensitization.

[0044] The device co-sensitized with compound SG1 and compound AJ502 obtained in Example 1 (the assembly method of the device is the same as in Application Example 1) was subjected to JV testing under simulated sunlight at AM 1.5G and IPCE testing after silicon cell calibration. The results are as follows. Figure 8 The data obtained for the sensitized device are as follows: Open circuit voltage V OC =0.81V, short-circuit current J SC =11.06mA cm -2 The fill factor FF = 64.52% and PCE = 5.9%. Both the open-circuit voltage and photoelectric conversion efficiency increased significantly after co-sensitization.

[0045] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the implementation. The scope of protection of the present invention should be determined by the scope defined in the claims. Other variations or modifications can be made based on the above description. Obvious variations or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A carbazole compound containing a triple bond, characterized in that, Its molecular structural formula is: 。 2. A method for preparing a carbazole compound containing a triple bond as described in claim 1, characterized in that, Includes the following steps: (1) Using 4,7-bis(5-bromo-4-hexylthiophene-2-)-2,1,3-benzothiadiazole as a π-bridge and ethyl 4-ethynylbenzoate as an acceptor, 4,7-bis(5-bromo-4-hexylthiophene-2-)-2,1,3-benzothiadiazole and ethyl 4-ethynylbenzoate were subjected to a Sonogashira coupling reaction. After the reaction was completed, the reaction solution was extracted with dichloromethane. The concentrate obtained was dissolved in the eluent and then separated and purified by column chromatography with silica gel. The eluent was collected and the elution was removed by evaporation to obtain compound I. (2) Compound II was subjected to a Suzuki coupling reaction with 4-bromo-N,N-bis[4-(2-ethylhexyloxy)phenyl]-aniline, followed by a Miyaura borylation reaction to obtain compound III; (3) Using compound III as a donor, compound I and compound III were subjected to a Suzuki coupling reaction, followed by hydrolysis to obtain the target product; The molecular structural formula of compound I is: The molecular structural formula of compound II is: The molecular structural formula of compound III is: 。 3. The preparation method according to claim 2, characterized in that, In step (1), the reaction time is 12-20 hours.

4. The preparation method according to claim 2, characterized in that, In step (1), the reaction is carried out under nitrogen protection.

5. The preparation method according to claim 2, characterized in that, In step (1), the reaction solvent is toluene, dichloromethane, chloroform, tetrahydrofuran or a mixture of 1,4-dioxane and water; the volume ratio of toluene, dichloromethane, chloroform or tetrahydrofuran to water is 5:1, and the volume ratio of 1,4-dioxane to water is 6:

1.

6. The preparation method according to claim 2, characterized in that, In step (1), the molar ratio of π-bridge to receptor is 1:0.6-1; In step (3), the molar ratio of compound I to the donor is 1:1.

5.

7. The preparation method according to claim 2, characterized in that, In step (1), the reaction temperature is 70-95℃.

8. The preparation method according to claim 2, characterized in that, In step (1), the eluent is a mixed solvent composed of petroleum ether and dichloromethane, wherein the volume ratio of petroleum ether to dichloromethane is 2-4:

1.

9. The use of a carbazole compound as a photosensitizer in dye-sensitized solar cells according to claim 1.

10. The application of the carbazole compound of claim 1, together with dye AJ502, as a photosensitizer in dye-sensitized solar cells.

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