A novel small-molecule electron acceptor material, a preparation method thereof and an organic solar cell
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NANKAI UNIV
- Filing Date
- 2026-06-16
- Publication Date
- 2026-07-24
Smart Images
Figure CN122444759A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of organic solar cell technology, specifically to a novel small molecule electron acceptor material with high near-infrared spectral absorption (cutoff absorption exceeding 1000 nm) and low on-voltage loss, its preparation method, and its application in organic solar cells. Background Technology
[0002] Organic solar cells (OSCs), as an emerging green energy technology, have shown broad application prospects in building-integrated photovoltaics (BIPV), portable devices, and the Internet of Things (IoT) due to their advantages such as lightweight, flexibility, and rich material systems. In recent years, their performance has made significant progress, with the power conversion efficiency (PCE) surpassing the key milestone of 20%. However, compared to traditional inorganic photovoltaics, further improvements in the efficiency of organic photovoltaic devices still face two major bottlenecks. First, organic materials have low dielectric constants and high exciton binding energies (0.1~1 eV), far exceeding those of inorganic semiconductors (~10 meV). This results in significantly higher turn-on losses for organic photovoltaic devices compared to inorganic photovoltaic devices, which is the key factor limiting the improvement of their PCE. Second, the cutoff absorption wavelength (λonset) of existing high-efficiency organic photovoltaic acceptor materials is generally ~900 nm. The development of high-efficiency narrow-bandgap organic photovoltaic acceptor materials exceeding 1000 nm is insufficient, leading to inadequate utilization of near-infrared light and limiting their further development in high-performance organic photovoltaic devices.
[0003] Therefore, fully leveraging the advantages of organic small molecule acceptor materials, such as their highly designable molecular structure and easily tunable energy levels, to develop near-infrared light-responsive organic photovoltaic materials with thin-film cutoff absorption exceeding 1000 nm, and to make fuller use of near-infrared light in the solar spectrum, is of great significance for improving the PCE of organic solar cells. However, according to the bandgap law, the narrower the bandgap, the stronger the molecular vibrational coupling, which leads to severe nonradiative recombination losses, thus limiting the performance improvement of narrow bandgap organic photovoltaic acceptor materials.
[0004] Therefore, developing novel small molecule acceptor materials that combine high efficiency in near-infrared spectroscopy (thin cutoff absorption exceeding 1000 nm) with low open-voltage loss is key to breaking through the performance bottleneck of organic optoelectronic devices. Summary of the Invention
[0005] This invention provides a novel small molecule electron acceptor material with efficient near-infrared spectral response (thin film cutoff absorption exceeding 1000 nm) and low on-voltage loss, as well as its preparation method and application. It aims to solve the technical problems of insufficient energy utilization of near-infrared light and severe non-radiative recombination of existing organic small molecule acceptor materials, resulting in low device photoelectric performance, especially their serious lack of application in tandem organic photovoltaic devices.
[0006] To achieve the above objectives, in a first aspect, the present invention provides a novel small molecule electron acceptor material with high near-infrared spectral absorption and low on-voltage loss, wherein the novel small molecule electron acceptor material is compound OSe-1, and its general chemical structure is shown below: In the formula, Selected from , or X is selected from -H, -F, -Cl, -I, -NO2, or -CN; n is 1 or 2; R1, R2, and R3 are each independent and are C. m H 2m+1 m is an integer from 1 to 100.
[0007] According to a second aspect of the present invention, the present invention also provides a method for preparing the novel small molecule electron acceptor material of the first aspect described above, comprising the following steps: S1, Compound 1 and Compound 2 are coupled via Stille coupling reaction to obtain Compound 3; wherein the chemical structures of Compound 1 and Compound 2 are shown in Formula (1) and Formula (2), respectively: (1) (2) Where n is 1 or 2; R1 is C m H 2m+1 m is an integer from 1 to 100; S2, compound 3 undergoes a Cadogan cyclization reaction to yield intermediate 4; wherein the chemical structures of compound 3 and intermediate 4 are shown in formulas (3) and (4): (3) (4) Where n is 1 or 2; C represents independent R1 and R2. m H 2m+1 m is an integer from 1 to 100; S3, intermediate 4, by using an alkyl halide as an alkylating agent, undergoes an N-alkylation reaction on a nitrogen-containing heterocycle to obtain compound 5; wherein, the chemical structure of compound 5 is shown in formula (5): (5) Where n is 1 or 2; R1, R2, and R3 are each independent and represented by C. m H 2m+1 m is an integer from 1 to 100; S4, compound 5 was aldehyde-substituted via the Wilsmayer-Hacker reaction to give compound 6; (6) Where n is 1 or 2; R1, R2, and R3 are each independent and represented by C. m H 2m+1 m is an integer from 1 to 100; S5, react compound 6 with the terminal compound to obtain the target compound OSe-1; the chemical structural formula of the terminal compound is shown in formula (7): (7) Where X is selected from -H, -F, -Cl, -I, -NO2, or -CN.
[0008] As a further preferred technical solution of the present invention, in the Stille coupling reaction of step S1, palladium dichloride bis(triphenylphosphine) is used as a catalyst to couple an organohalide compound 1 and an organotin reagent compound 2 to obtain compound 3; and / or, the molar ratio of compound 1 to compound 2 is 1:(2~2.5).
[0009] As a further preferred technical solution of the present invention, in step S2, the Cadogan cyclization reaction uses triphenylphosphine as a reducing agent and N-methylpyrrolidone (NMP) as a solvent. At a temperature of 150~220°C, the nitro group in the precursor compound 3 is reduced, and the nitrogen atom attacks the adjacent thiophene ring carbon atom, thereby forming a new carbon-nitrogen bond and completing the cyclization to obtain intermediate 4.
[0010] As a further preferred technical solution of the present invention, in step S3, the molar ratio of intermediate 4 to alkyl halide is 1:(3~5).
[0011] As a further preferred embodiment of the present invention, in step S4, the Wilsmayer-Hacker reaction is carried out through... N， N - Dimethylformamide and phosphorus oxychloride were used to aldehyde-formaldehyde compound 5 in water.
[0012] According to a third aspect of the present invention, the present invention also provides the application of the above-described novel small molecule electron acceptor material in organic solar cells.
[0013] According to a fourth aspect of the present invention, the present invention also provides an organic solar cell, wherein the active layer comprises a donor material and a composite acceptor material; the composite acceptor material comprises a first acceptor material and a second acceptor material, wherein the first acceptor material is the novel small molecule electron acceptor material according to claim 1 or the novel small molecule electron acceptor material prepared by the preparation method according to any one of claims 2-6, and the second acceptor material is L8-BO (CAS No.: 2668341-40-8).
[0014] As a further preferred technical solution of the present invention, the donor material is PBDB-T, and its CAS number is 1415929-80-4.
[0015] As a further preferred embodiment of the present invention, the mass ratio of the donor material, the first acceptor material and the second acceptor material is 1:(0.8~1.2):(0~0.4).
[0016] Compared with the prior art, the present invention can achieve the following beneficial effects: The small molecule electron acceptor material OSe-1 provided by this invention has a highly efficient near-infrared spectrum ( λ onset Achieving a response greater than 1000 nm and low on-voltage loss. First, a selenophenol unit is introduced, utilizing the polarizability and heavy atom effect of selenium atoms to enhance intermolecular interactions and broaden the molecular absorption spectrum. Through side-chain modification, multiple intramolecular oxygen-sulfur nonvalent interactions are introduced. On one hand, this enhances the intramolecular ICT effect and reduces the band gap; on the other hand, the multiple oxygen-sulfur nonvalent bonds lock the molecular configuration, enhancing molecular rigidity, suppressing vibrations, and reducing nonradiative recombination and on-voltage loss. Ultimately, this enables single-cell and tandem organic solar cells based on OSe-1 to achieve [the desired response]. λ onset The photovoltaic response characteristics exceeding 1000 nm yielded energy conversion efficiencies of over 17% and 21%, respectively, representing the highest device efficiencies to date in the field of organic solar cell research with spectral responses exceeding 1000 nm. This demonstrates the significant potential of the OSe-1 molecule in the fabrication of high-performance tandem photovoltaic devices.
[0017] The present invention provides a high efficiency near-infrared spectroscopy ( λ onset OSe-1 is a small molecule electron acceptor material with a response greater than 1000 nm and low on-voltage loss characteristics. Its preparation process is controllable, and it possesses precise molecular weight, controllable structure, and is easily purified. Attached Figure Description
[0018] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0019] Figure 1 For product 2A in Example 1 1 H NMR spectrum; Figure 2 For product 4A in Example 1 1 H NMR spectrum; Figure 3 For product 5A in Example 1 1 H NMR spectrum; Figure 4 For product OSe-1 in Example 11 H NMR spectrum; Figure 5 This is a schematic diagram of the single-crystal structure of product OSe-1 in Example 1. Figure 6 The UV-Vis absorption spectra of OSe-1 solution and film are shown. Figure 7 The current density-photovoltage curves and external quantum efficiency curves are for the organic solar cell devices in Application Examples 1 and 2.
[0020] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation
[0021] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.
[0022] Unless otherwise defined, the technical terms used in the following embodiments have the same meanings as commonly understood by those skilled in the art to which this invention pertains. Unless otherwise specified, the experimental reagents used in the following embodiments are conventional biochemical reagents; and the experimental methods described are conventional methods.
[0023] Example 1 This embodiment provides a novel small molecule acceptor material, OSe-1, whose chemical structure is shown below: The specific preparation method is as follows: S1, 0.5 g (1.15 mmol) of compound 1A, 1.5 g (2.59 mmol) of compound 1B, and 30 mL of toluene were added to a two-necked reaction flask. Under an argon atmosphere and ice bath, 84 mg (0.12 mmol) of bis(triphenylphosphine)-palladium dichloride (Pd(PPh3)3Cl2) was added as a catalyst. The reaction was carried out at 90 °C for 14 h, then cooled to room temperature. The reaction product was extracted with dichloromethane, dried over anhydrous sodium sulfate, and the solvent was removed by vacuum rotary evaporation. Column chromatography was then performed using a 1:1 eluent of petroleum ether and dichloromethane to give compound 2A (0.65 g, yield 56%). 1 H NMR spectrum as shown Figure 1 As shown, from Figure 1 This indicates that it was successfully prepared.
[0024] 1A 1B 2A In S2, 0.57 g (0.57 mmol) of compound 2A, 1.48 g (5.7 mmol) of triphenylphosphine, and 30 mL of ultra-dry solvent N-methylpyrrolidone (NMP) were added to a 100 mL two-necked reaction flask. The mixture was reacted at 180 °C for 12 h under an argon atmosphere. The reaction yielded crude intermediate 3A, which was not further purified. Then, 0.46 g (2.76 mmol) of potassium hydroxide (KOH), 0.04 g (0.25 mmol) of potassium iodide (KI), and 0.69 g (2.76 mmol) of 2-butyl-1-bromooctane were added directly to the above reaction system, which had been cooled to room temperature. The reaction was carried out overnight at 90 °C under an argon atmosphere. The reaction was then complete. The reaction system was extracted with ethyl acetate, dried over anhydrous sodium sulfate, and the solvent was removed by vacuum rotary evaporation. The mixture was then eluted by column chromatography with a 1:1 volume ratio of petroleum ether and dichloromethane to give compound 4A (0.31 g, yield 35%). 1 H NMR spectrum as shown Figure 2 As shown, from Figure 2 It can be concluded that compound 4A was successfully prepared.
[0025] 2A 3A 4A In step S3, 0.31 g (0.24 mmol) of compound 4A and 30 mL of 1,2-dichloroethane were added to a 100 mL two-necked reaction flask. Then, 0.18 mL of N,N-dimethylformamide and 0.2 mL of phosphorus oxychloride were added under ice bath conditions. The reaction was carried out at 50 °C for 12 h. The reaction was then quenched with a saturated sodium acetate aqueous solution, and stirred at room temperature for 2 h. The reaction product was extracted with dichloromethane, and the solvent was removed by vacuum rotary evaporation. The product was then eluted by column chromatography with an organic eluent (petroleum ether and dichloromethane in a 4:1 volume ratio) to give compound 5A (0.27 g, yield 84%). Compound 5A... 1 H NMR spectrum as shown Figure 3 As shown, from Figure 3 It can be concluded that compound 5A was successfully prepared.
[0026] 4A 5A In step S4, 0.27 g (0.2 mmol) of compound 5A and 0.21 g (0.80 mmol) of the terminal compound (CAS No.: 2197167-50-1) were added to a single-necked reaction flask. Under argon protection, 25 mL of chloroform and 0.3 mL of pyridine were added, and the reaction was carried out overnight at room temperature. After the reaction was complete, the mixture was cooled to room temperature, and then 25 mL of methanol was added to quench the reaction. The precipitated solid was collected and eluted by column chromatography with an organic eluent (petroleum ether and chloroform in a volume ratio of 1:5) to give compound OSe-1 (0.28 g, yield 70%). The composition of compound OSe-1... 1 H NMR spectrum as shown Figure 4 As shown, from Figure 4 It can be concluded that compound OSe-1 was successfully prepared.
[0027] 5A OSe-1 The performance of compound OSe-1 prepared in Example 1 was tested, as follows: (1) Absorption spectroscopy test Compound OSe-1 was dissolved in chloroform solution to obtain OSe-1 solution; the OSe-1 solution was spin-coated onto the surface of a quartz plate to obtain OSe-1 film; the UV-Vis absorption spectra of OSe-1 solution (OSe-1-sol) and OSe-1 film (OSe-1-film) were measured respectively, and the test results are as follows. Figure 5 As shown.
[0028] from Figure 5 It can be seen that OSe-1 has a maximum absorption wavelength of 826 nm and 935 nm in solution and thin film forms, respectively, and a cutoff absorption wavelength of 1034 nm in thin film form.
[0029] (2) Single crystal structure analysis Single crystals of OSe-1 were prepared by solution diffusion and analyzed. The results are as follows: Figure 5 As shown below, the distances between the side-chain oxygen atom and the conjugated backbone sulfur atom are 2.79 Å and 2.76 Å, respectively, which are less than the sum of the van der Waals radii of the oxygen and sulfur atoms, proving that the oxygen atom in the side chain and the sulfur atom in the fused ring conjugated backbone form a non-covalent interaction.
[0030] According to the band gap law, the narrower the band gap, the stronger the molecular vibrational coupling, which leads to severe nonradiative recombination losses, making it difficult to obtain small-molecule electron acceptor materials that combine low open-voltage losses and efficient near-infrared spectral response. For the small-molecule compound OSe-1, on the one hand, by introducing selenophenol units, the polarizability and heavy atom effect of selenium atoms are utilized to enhance intermolecular interactions, broaden the molecular absorption spectrum, and reduce the band gap; on the other hand, the outer selenophenol units... The introduction of an alkoxymethyl side chain at the --position allows for non-covalent interactions between the oxygen atom of the side chain and the sulfur atom of the fused-ring conjugated backbone, thereby introducing multiple oxygen-sulfur non-covalent interactions within the molecule. This enhances the intramolecular ICT effect and reduces the band gap; furthermore, the multiple oxygen-sulfur non-covalent bonds lock the molecular configuration, increasing molecular rigidity, suppressing vibrations, and reducing nonradiative recombination and open-voltage losses. This molecular design strategy was validated using the single-crystal structure of OSe-1, marking the first observation of this structure in a near-infrared fused-ring small molecule acceptor.
[0031] The properties of the small molecule compound OSe-1 were compared with those of other known small molecule compounds Se-1 and BZO-4Cl, and the relevant properties are summarized in Table 1.
[0032] The structural formulas of the small molecule compounds Se-1 and BZO-4Cl are as follows: .
[0033] Table 1 For Se-1, which is entirely substituted with alkyl side chains, the maximum absorption peaks in solution and film are 797 nm and 891 nm, respectively, with a redshift of 94 nm from solution to film. In contrast, OSe-1 shows a significant redshift in both solution and film, at 825 nm and 935 nm, respectively, with a redshift of 109 nm from solution to film. This is mainly due to the multiple non-covalent interactions between the alkoxymethyl side chain and the conjugated backbone, which enhance the intramolecular ICT effect and increase molecular rigidity, thus facilitating the formation of a tight molecular packing pattern for OSe-1.
[0034] For the molecule BZO-4Cl, where Se is replaced by S in the structure, it is difficult to synthesize OSe-1 molecules according to the synthetic route of BZO-4Cl because the selenophene unit is significantly more reactive than the thiophene unit. In the molecule BZO-4Cl, no multiple non-covalent interactions between the side chain oxygen atoms and the conjugated backbone were observed. Its maximum absorption peak in the thin film is 909 nm, and the cutoff absorption in the thin film is 990 nm, which does not exceed 1000 nm. In contrast, the cutoff absorption in the thin film of OSe-1 reaches 1034 nm.
[0035] Application Example 1 This application example provides a single-junction organic solar cell device, the fabrication method of which includes: (1) The ITO conductive glass substrate was ultrasonically cleaned for 15 minutes each in an ultrasonic machine using detergent, deionized water and isopropanol solvent. The cleaned ITO conductive glass substrate was then placed in an ultraviolet-ozone chamber for 15 minutes to obtain the treated ITO conductive glass substrate. (2) The self-assembled monomolecule 3-BPIC (CAS: 3038707-49-9) was dissolved in chromatographic grade anhydrous ethanol and stirred on a magnetic stirrer at room temperature for 2 hours to obtain a self-assembled molecule 3-BPIC solution with a concentration of 0.8 mg / mL. A self-assembled molecular 3-BPIC solution was spin-coated onto the upper surface of the treated ITO conductive glass substrate at a speed of 3000 r / min using a spin coater. Then, it was placed on an annealing station at 100°C and annealed for 10 min to form a self-assembled molecular 3-BPIC layer, i.e., a hole transport layer. (3) The donor material PBDB-T (CAS: 1415929-80-4), the acceptor material OSe-1 (Example 1) and the acceptor material L8-BO (CAS: 2668341-40-8) were mixed in a mass ratio of 1:0.8:0.4. The mixture was dissolved in chloroform and stirred on a hot plate for 2 hours to obtain a mixed solution. The concentration of PBDB-T was 7 mg / mL. L8-BO was used as the third component to construct a ternary blend film, which optimized the film absorption and morphology of the binary device, improved the photon utilization efficiency, and thus improved the energy conversion efficiency of the device.
[0036] The mixed solution was spin-coated onto the hole transport layer at 3000 rpm for 30 seconds using a spin coater, and then placed on a hot plate at 85°C for annealing for 10 minutes to form an active layer with a thickness of 120 nm. (4) PNDIT-F3N (CAS No.: 1800206-46-5) was dissolved in a mixed solvent of methanol and glacial acetic acid with a concentration of 1 mg / mL to obtain a PNDIT-F3N solution; wherein the mixed solvent of methanol and glacial acetic acid has a volume percentage of 99.7 vol% and a volume percentage of glacial acetic acid of 0.3 vol%.
[0037] The mixed solution was spin-coated onto the active layer at 3000 rpm for 20 seconds using a spin coater to form an electron transport layer with a thickness of 5 nm. (5) Transfer the product from step (4) into the physical vapor deposition chamber and evacuate to a pressure of 2 × 10⁻⁶. -6Pa is used to heat a silver (Ag) target material to prepare a metal electrode (Ag electrode) with a thickness of 150 nm on the surface of the electron transport layer away from the active layer, thus obtaining an organic solar cell.
[0038] Application Example 2 Application Example 2 provides an organic solar cell tandem device, the fabrication method of which includes: (1) The ITO conductive glass substrate was ultrasonically cleaned for 15 minutes each in an ultrasonic machine using detergent, deionized water and isopropanol solvent. The cleaned ITO conductive glass substrate was then placed in an ultraviolet-ozone chamber for 15 minutes to obtain the treated ITO conductive glass substrate. (2) Dissolve the self-assembled monomolecule 3-BPIC-F in chromatographic grade anhydrous ethanol and stir on a magnetic stirrer at room temperature for 2 hours to obtain a self-assembled molecule 3-BPIC solution with a concentration of 0.8 mg / mL. A self-assembled molecule 3-BPIC-F solution was spin-coated onto the upper surface of the treated ITO conductive glass substrate at a speed of 3000 r / min using a spin coater. Then, it was annealed on an annealing table at 100°C for 10 min to form a self-assembled molecule 3-BPIC-F layer, i.e., a hole transport layer. (3) The donor material PB2 and the acceptor material α-F were mixed at a mass ratio of 1:1.2. The mixture was dissolved in chloroform and stirred on a hot plate for 2 hours to obtain a mixed solution; the concentration of PB2 was 7 mg / mL. The mixed solution was spin-coated onto the hole transport layer at 2000 rpm for 30 seconds using a spin coater, and then heat-annealed on a hot plate at 100°C for 10 minutes to form an active layer with a thickness of 160 nm. (4) Prepare an aqueous dispersion of zinc oxide nanoparticles at a concentration of 15 mg / mL. Use a spin coater to spin coat the mixture at a speed of 2000 rpm for 30 s to selectively coat the zinc oxide layer onto the blend film of PB2 and α-F.
[0039] (5) Prepare an aqueous dispersion of zinc oxide nanoparticles at a concentration of 15 mg / mL. Spin coat the mixture at 2000 rpm for 30 s to form a zinc oxide layer on the blend film of PB2 and α-F. Then, heat-anneal the film on a hot plate at 100℃ for 10 min. (6) PEDOT:PSS (model: Heraeus Clevios™ AI 4083) diluted with deionized water was spin-coated onto the ZnO layer at a speed of 4000 rpm / s, and then placed on a hot plate at 120°C for heat annealing for 5 min. (7) The donor material PBDB-T (CAS: 1415929-80-4), the acceptor material OSe-1, and the acceptor material L8-BO were mixed at a mass ratio of 1:0.8:0.4. The mixture was dissolved in chloroform and stirred on a hot plate for 2 hours to obtain a mixed solution; the concentration of PBDB-T was 7 mg / mL. The mixed solution was spin-coated onto the hole transport layer at 3000 rpm for 30 seconds using a spin coater, and then placed on a hot plate at 85°C for annealing for 10 minutes to form an active layer with a thickness of 120 nm. (8) Dissolve PNDIT-F3N (CAS No.: 1800206-46-5) in a mixed solvent of methanol and glacial acetic acid with a concentration of 1 mg / mL to obtain a PNDIT-F3N solution; wherein the mixed solvent of methanol and glacial acetic acid has a volume percentage of 99.7 vol% and a volume percentage of glacial acetic acid of 0.3 vol%.
[0040] The mixed solution was spin-coated onto the active layer at 3000 rpm for 20 seconds using a spin coater to form an electron transport layer with a thickness of 5 nm. (9) Transfer the product from step (8) into the physical vapor deposition chamber and evacuate to a pressure of 2 × 10⁻⁶. -6 Pa is used to heat a silver (Ag) target material to prepare a metal electrode (Ag electrode) with a thickness of 150 nm on the surface of the electron transport layer away from the active layer, thus obtaining an organic solar cell.
[0041] Comparative Application Example 1 As a control test for Application Example 1, the only difference is that the acceptor material OSe-1 (Example 1) in Application Example 1 is replaced with the small molecule Se-1 by the same mass. The remaining steps are consistent with Application Example 1, and finally an organic solar cell is obtained.
[0042] Comparative Application Example 2 As a control test for Application Example 1, the only difference is that the acceptor material OSe-1 (Example 1) in Application Example 1 is replaced by the same mass of small molecule BZO-4Cl. The remaining steps are consistent with Application Example 1, and finally an organic solar cell is obtained.
[0043] Comparative Application Example 3 As a control test for Application Example 1, the only difference is that the acceptor material L8-BO in Application Example 1 is removed, while the rest of the steps are the same as in Application Example 1, and finally an organic solar cell is obtained.
[0044] The organic solar cells fabricated in corresponding use cases 1 and 2, as well as comparative application examples 1, 2, and 3, were subjected to performance testing. The testing method was as follows: under standard sunlight (AM 1.5G) irradiation conditions, the open-circuit voltage of the above-mentioned organic solar cell devices was measured using a computer-controlled Keithley 2400 digital source meter. V oc ), short-circuit current density ( J sc ), integral short-circuit current density ( J sc cal The fill factor (FF) and photoelectric conversion efficiency (PCE) were tested, and the test results are shown in Table 2.
[0045] Table 2 Performance test results of organic solar cells As shown in Table 2, the OSe-1-containing organic solar cell prepared using Example 1 achieved a current of 31.33 mA / cm². -2 The short-circuit current density and photoelectric conversion efficiency are 17.27%. Compared with existing organic photovoltaic active layer systems (as shown in Table 3), the single-junction device of organic solar cell based on OSe-1 achieves the champion PCE with a cutoff absorption wavelength greater than 1000 nm.
[0046] Table 3 Summary of device performance for organic photovoltaic acceptors with cutoff absorption wavelengths greater than 1000 nm Based on the OSe-1-containing organic solar cell tandem devices fabricated in Application Examples 1 and 2, the highest power conversion efficiency (PCE) with a cutoff absorption wavelength greater than 1000 nm and a PCE exceeding 21% was achieved. This work demonstrates the great potential of OSe-1 molecules in the fabrication of high-performance tandem photovoltaic devices.
[0047] The current density-photovoltage (JV) curves and external quantum efficiency (EQE) curves of the organic solar cells prepared in Application Examples 1 and 2 are shown below. Figure 7 As shown, where: A) is the current density-photovoltage curve (JV curve). Figure 7 (B) is the external quantum efficiency (EQE) curve corresponding to Application Example 1. Figure 7 C) is the external quantum efficiency (EQE) curve corresponding to application example 2. According to... Figure 7 It can be seen that the organic solar cell prepared using compound OSe-1 in Example 1 of the present invention has excellent short-circuit current and an external quantum efficiency of over 85%, exhibiting excellent photoelectric performance.
[0048] Energy loss is performed on the organic solar cell prepared in accordance with use case 1.E loss The test was performed using electroluminescence EQE (EQEEL) and high-sensitivity EQE spectroscopy (FTPS-EQE). The calculation formula is as follows: in, E g PV The band gap represents the hybrid thin film, q is the elementary charge, is the maximum voltage based on the Shockley-Quiselle (SQ) limit, and is the open-circuit voltage when only radiative recombination exists. V oc This represents the open-circuit voltage. The test results are shown in Table 4. Table 4 Energy Loss Analysis of Organic Solar Cells As shown in Table 4, the organic solar cell prepared using compound OSe-1 as the acceptor material in Application Example 1 still achieves an on-state voltage of 0.753 V when the cutoff absorption wavelength is greater than 1000 nm, thanks to its low on-state voltage loss of 0.517 V.
[0049] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and various changes or modifications can be made to these embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is defined only by the appended claims.
Claims
1. A novel small molecule electron acceptor material, characterized in that, The novel small molecule electron acceptor material is compound OSe-1, whose general chemical structure is shown below: ； In the formula, Selected from , or X is selected from -H, -F, -Cl, -I, -NO2, or -CN; n is 1 or 2; R1, R2, and R3 are each independent and are C. m H 2m+1 m is an integer from 1 to 100.
2. The method for preparing the novel small molecule electron acceptor material according to claim 1, characterized in that, Includes the following steps: S1, Compound 1 and Compound 2 are coupled via Stille coupling reaction to obtain Compound 3; wherein the chemical structures of Compound 1 and Compound 2 are shown in Formula (1) and Formula (2), respectively: （1） （2） Where n is 1 or 2; R1 is C m H 2m+1 m is an integer from 1 to 100; S2, compound 3 undergoes a Cadogan cyclization reaction to yield intermediate 4; wherein the chemical structures of compound 3 and intermediate 4 are shown in formulas (3) and (4): （3） （4） Where n is 1 or 2; C represents independent R1 and R2. m H 2m+1 m is an integer from 1 to 100; S3, intermediate 4, by using an alkyl halide as an alkylating agent, undergoes an N-alkylation reaction on a nitrogen-containing heterocycle to obtain compound 5; wherein, the chemical structure of compound 5 is shown in formula (5): （5） Where n is 1 or 2; R1, R2, and R3 are each independent and represented by C. m H 2m+1 m is an integer from 1 to 100; S4, compound 5 was aldehyde-substituted via the Wilsmayer-Hacker reaction to give compound 6; （6） Where n is 1 or 2; R1, R2, and R3 are each independent and represented by C. m H 2m+1 m is an integer from 1 to 100; S5, react compound 6 with the terminal compound to obtain the target compound OSe-1; the chemical structural formula of the terminal compound is shown in formula (7): （7） Where X is selected from -H, -F, -Cl, -I, -NO2, or -CN.
3. The preparation method according to claim 2, characterized in that, In the Stille coupling reaction of step S1, palladium dichloride bis(triphenylphosphine) is used as a catalyst to couple an organohalide compound 1 and an organotin reagent compound 2 to obtain compound 3. And / or, the molar ratio of compound 1 to compound 2 is 1:(2~2.5).
4. The preparation method according to claim 2, characterized in that, In step S2, the Cadogan cyclization reaction uses triphenylphosphine as a reducing agent. At a temperature of 150~220℃, the nitro group in the precursor compound 3 is reduced, and the nitrogen atom attacks the adjacent thiophene ring carbon atom, thereby forming a new carbon-nitrogen bond and completing the cyclization to obtain intermediate 4.
5. The preparation method according to claim 2, characterized in that, In step S3, the molar ratio of intermediate 4 to alkyl halide is 1:(3~5).
6. The preparation method according to claim 2, characterized in that, In step S4, the Wilsmayer-Hacker reaction is carried out through... N, N - Dimethylformamide and phosphorus oxychloride were used to aldehyde-formaldehyde compound 5 in water.
7. The application of the novel small molecule electron acceptor material according to claim 1 or the novel small molecule electron acceptor material prepared by the preparation method according to any one of claims 2-6 in organic solar cells.
8. An organic solar cell, characterized in that, Its active layer includes a donor material and a composite acceptor material; the composite acceptor material includes a first acceptor material and a second acceptor material, wherein the first acceptor material is the novel small molecule electronic acceptor material according to claim 1 or the novel small molecule electronic acceptor material prepared by the preparation method according to any one of claims 2-6, and the second acceptor material is L8-BO.
9. The organic solar cell according to claim 8, characterized in that, The donor material is PBDB-T.
10. The organic solar cell according to claim 8 or 9, characterized in that, The mass ratio of the donor material, the first acceptor material, and the second acceptor material is 1:(0.8~1.2):(0~0.4).