An organic small molecule semiconductor bifunctional material, its preparation method and its application

Abstract

This invention relates to a bifunctional organic small-molecule semiconductor material, its preparation method, and its applications. It is used as an electron donor or electron acceptor in the photoactive layer material of organic photovoltaic cells, and its addition to the active layer in appropriate proportions can significantly improve the performance of organic photovoltaic devices, achieving enhanced photoelectric conversion efficiency. This type of compound is based on an indole-dependent fused ring as the electron-donating unit and a thiophene ring as the bridging unit. Utilizing the differences in thiophene connection positions and end-group electrophoretic units, a wide-bandgap organic small-molecule semiconductor with a twisted main chain structure is formed. This semiconductor not only possesses high hole mobility but also a higher lowest unoccupied molecular orbital (LUMO) energy level, and has the following general formula structure.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of photoelectric functional materials, and particularly relates to an organic small-molecule semiconductor bifunctional material, a preparation method and application thereof, and the application of the molecule as a bifunctional material in a photoactive layer, which can be added into the active layer as an electron donor material or an electron acceptor material according to a corresponding proportion, and the application in an organic solar cell (OSC) device can significantly improve the comprehensive performance of the device. BACKGROUND

[0002] An organic solar cell (OSC) is a renewable and clean energy source with potential application value. Due to its inherent advantages such as light weight, flexibility, large-scale production, etc., it has attracted widespread attention from the scientific and industrial communities, and great progress has been made in material and device design. At present, the new electron acceptor material is mainly represented by Y6 and its analogues, and with the continuous improvement of device technology, the photoelectric conversion efficiency (PCE) in a single-junction cell has reached a commercial level, and in particular, the short-circuit current density (J SC ) of the OSC device has reached a high level, which is comparable to that of a perovskite solar cell. However, the open-circuit voltage (V OC ) is generally not ideal, which hinders the further improvement of the performance of the OSC device. At the same time, another problem that needs to be solved for high-efficiency OSC devices is the large difference in charge mobility between the conjugated polymer electron donor and the electron acceptor material, which leads to charge accumulation and thus affects the fill factor (FF) of the device. Therefore, increasing V OC and improving charge mobility are necessary ways to improve the performance of the OSC device.

[0003] The three-dimensional excessive aggregation and high crystallinity of Y6 and its derivatives can cause an unproportional charge mobility in the active layer of the organic solar cell, in which the hole mobility (μ h ) is significantly lower than the electron mobility (μ e ). This difference leads to charge accumulation, which negatively affects the fill factor (FF). Therefore, improving μ h based on the Y6 system is a strategy, for example, introducing IDTT-M into the PM6:Y6 system, thereby increasing μ h to 6.44×10 -4 cm 2 V -1 s -1 , which exceeds the 5.23×10 -4 cm 2 V -1 s -1This improves the device's FF to 73.89% and PCE to 16.64%, which is superior to the corresponding binary devices' 72.45% and 15.48% [L. Xiao, X. Wu, G. Ren, MA Kolaczkowski, G. Huang, W. Tan, L. Ma, Y. Liu, X. Peng, Y. Min, and Y. Liu: Highly Efficient Ternary Solar Cells with Efficient Resonance Energy Transfer for Simultaneously Enhanced Photovoltaic Parameters, Advanced Functional Materials, 2021, 31(41), 2105304. Chen et al. prepared star-shaped molecules TF1 to suppress excessive aggregation of Y6 and enhance the stability of the morphology. This method enables μ... h Increased from 1.99 to 3.04 × 10 -4 cm 2 V -1 s -1 And it achieves a more balanced μ e / μ h The ratio was 1.36, lower than the 1.75 of the PM6:Y6 system. After optimization, the FF increased to 75.08%, and the PCE increased to 16.91%. Furthermore, Chen et al. added a novel multifunctional molecule, BDTPF4-C6, to the PM6:Y6 binary blend. This method significantly improved the crystallinity of PM6, reduced the π-π packing distance, and μ... h Increased from 1.41 to 2.95 × 10 -4 cm 2 V -1 s -1 This leads to a more balanced charge transport, μ e / μ hThe ratio increased from 1.54 to 1.2. As a result, the overall device performance was improved, with FF reaching 79.16% and PCE reaching 17.93% [X.Liao,M.Liu,H.Pei,P.Zhu,X.Xia,Z.Chen,Y.Zhang,Z.Wu,Y.Cui,G.Xu,M.Gao,L.Ye,R.Ma,T.Liu,X.Lu,H.Zhu,and Y.Chen:'Regulating Crystallinity Mismatch Between Donor and Acceptor to Improve Exciton / Charge Transport in Efficient OrganicSolar Cells,Angewandte Chemie-International Edition,2024,63(11),e202318595.].

[0004] With the enhancement of μ h In contrast, in binary devices based on the Y-system, adding an appropriate third component can inhibit the excessive aggregation of Y-type receptors and moderately reduce μ. e This is another strategy to achieve balanced charge transport efficiency, and it can also effectively improve the device FF and overall efficiency of the Y6 system. For example, Kan et al. replaced 1-chloronaphthalene with 1-fluoronaphthalene in the PM6:Y6 system, which promoted the miscibility of the phase and improved the morphological properties. This modification leads to μ h It is 5.24 × 10 -4 cm 2 V -1 s -1 μ e It is 5.28×10 -4 cm 2 V -1 s -1 All are lower than the device values ​​(μ) of chloronaphthalene. h and μ e The values ​​are 7.34 and 5.55 × 10, respectively. -4 cm 2 V -1 s -1 ), but μ h / μ eThe ratio is more balanced, which can increase FF from 71.9% to 77.8% and PCE from 15.7% to 17.5% [J.Lv,H.Tang,J.Huang,C.Yan,K.Liu,Q.Yang,D.Hu,R.Singh,J.Lee,S.Lu,G.Li,andZ.Kan:Additive-induced Miscibility Regulation and Hierarchical Morphology Enable 17.5% BinaryOrganic Solar Cells,Energy&Environmental Science,2021,14(5),3044-3052.].

[0005] In their previous research, the inventors used amorphous small molecule acceptor IO-4Cl as a third component in the PM6:Y6 system. This prevented excessive aggregation of Y6, thereby balancing the charge mobility of PM6:Y6-based devices and increasing Vt. OC A PCE of 17.49% was achieved [S. Liu, Z. Xue, Z. Liang, B. Zhao, W. Wang, Z. Cong, H. Wu, G. Lu, J. Zheng, and C. Gao: 'High-Performance PM6:Y6-Based Ternary Solar Cells with Enhanced Open Circuit Voltage and Balanced Mobilities via Doping a Wide-Band-Gap Amorphous Acceptor, ACS Applied Materials and Interfaces, 2024, 16(28), 36705-36714.]. Adding a high-LUMO-energy amorphous small molecule acceptor provides another method to improve the photovoltaic performance of PM6:Y6-based devices. In summary, these strategies can all improve device performance to some extent, but they are generally used as a third component (additive) to improve the active layer morphology, and challenges such as low open-circuit voltage and unbalanced mobility still exist. Summary of the Invention

[0006] To address the shortcomings or deficiencies of existing technologies, this invention provides an organic small molecule semiconductor material. By utilizing steric hindrance effects and the push-pull electron properties of substituents, the HOMO and LUMO energy levels, optical band gap, and charge transport efficiency of the material can be adjusted. This type of molecule can be used as a bifunctional material in the photoactive layer of organic photovoltaic cells, either as an electron donor or electron acceptor, or added to the active layer in appropriate proportions. Its application in organic solar energy devices can significantly improve the performance of the devices.

[0007] To achieve the above objectives, the technical solution adopted by the present invention includes:

[0008] An organic small molecule semiconductor bifunctional material, the structure of which is shown in Formula I:

[0009]

[0010] In the formula, R1 is one of alkyl, alkyl or alkoxy-substituted phenyl and alkyl or alkoxy-substituted thiophene groups having 1 to 20 carbon atoms;

[0011] R2 is a hydrogen atom, an alkyl group, or an alkoxy group;

[0012] R3 is a straight-chain or branched alkyl group having 1 to 12 carbon atoms;

[0013] X is an O, S, or Se atom.

[0014] Optionally, R2 is an alkoxy group having 1 to 20 carbon atoms.

[0015] Optionally, R2 is an alkyl group having 1 to 20 carbon atoms.

[0016] Optionally, the structure of the material is as follows:

[0017]

[0018] Optional, including:

[0019]

[0020] Take 2.96 g of compound 1 and 2.80 g of compound 2, dissolve them in 160 ml of toluene, under nitrogen protection, add 240 mg of catalyst Pd(PPh3)4, heat to 90 °C overnight, cool, remove the solvent by rotary evaporation and dissolve in water, extract three times with 50 ml of ethyl acetate, combine the organic phases, add anhydrous magnesium sulfate and dry for 2 hours, filter to remove the drying agent, purify the obtained product by column chromatography using 200-300 mesh silica gel column, with ethyl acetate:n-hexane = 1:100 volume ratio as eluent, to obtain 2.90 g of red solid compound 3;

[0021] 120 mg of compound 3 and 85 mg of 1,3-diethyl-2-thiophenthionone dihydropyrimidine-4,6(1-hydro,5-hydro)-dione were dissolved in 15 mL of chloroform. 0.4 mL of pyridine was added, and the mixture was heated to 65 °C and stirred for 6 hours. After cooling, 20 mL of water was added, and the mixture was extracted with chloroform. The organic phase was dried over anhydrous magnesium sulfate and concentrated. The solid was then precipitated in methanol and filtered to obtain a solid. The product was further purified by column chromatography using 200-300 mesh silica gel and chloroform as the eluent, finally yielding 120 mg of black solid.

[0022] The application of any of the organic small molecule semiconductor bifunctional materials described in this invention as electron donors or electron acceptors in the photoactive layer material of organic photovoltaic cells.

[0023] Optionally, the active layer of the photoactive bifunctional material is a Z10:Y6 mass ratio system of 1:1.2, where Z10 is the donor and Y6 is the acceptor;

[0024] When organic small molecule semiconductor bifunctional materials are incorporated into Y6 as acceptors, the mass ratio of organic small molecule semiconductor bifunctional materials to Y6 acceptors is 1:(11~23);

[0025] When organic small molecule semiconductor bifunctional material is incorporated into Z10 as a donor, the mass ratio of organic small molecule semiconductor bifunctional material to Z10 donor is 1:(9-19).

[0026] Optionally, the active layer of the photoactive bifunctional material is a PM6:BTP-eC9 mass ratio system of 1:1.2, where PM6 is the donor and BTP-eC9 is the acceptor.

[0027] When organic small molecule semiconductor bifunctional materials are incorporated into BTP-eC9 as acceptors, the mass ratio of organic small molecule semiconductor bifunctional materials to BTP-eC9 acceptors is 1:(11~23).

[0028] When organic small molecule semiconductor bifunctional materials are incorporated into PM6 as donors, the mass ratio of organic small molecule semiconductor bifunctional materials to PM6 donors is 1:(9-19).

[0029] Optionally, the active layer of the photoactive bifunctional material is a PM6:L8-BO mass ratio system of 1:1.2, where PM6 is the donor and L8-BO is the acceptor.

[0030] When organic small molecule semiconductor bifunctional material is incorporated into L8-BO as an acceptor, the mass ratio of organic small molecule semiconductor bifunctional material to L8-BO acceptor is 1:(11~23).

[0031] When organic small molecule semiconductor bifunctional materials are incorporated into PM6 as donors, the mass ratio of organic small molecule semiconductor bifunctional materials to PM6 donors is 1:(9-19).

[0032] The beneficial effects of this invention are:

[0033] The organic small-molecule semiconductor bifunctional material provided by this invention introduces an electron-deficient unit into the 4-position of the bridging thiophene ring, introducing a certain degree of twisting into the molecular backbone, effectively regulating the absorption spectrum and energy levels of the material. This small-molecule compound possesses a wide optical band gap, a strong absorption coefficient, good charge transport performance, and a higher lowest unoccupied molecular orbital (LUMO) energy level. As a bifunctional material for organic solar cells, it can be added to the active layer in appropriate proportions as an electron donor or electron acceptor material. It can be blended with electron donor polymers such as Z10 and PM6, and electron acceptor materials such as Y6, L8-BO, and BTP-eC9 to prepare organic solar energy devices, resulting in improved open-circuit voltage and fill factor, and a significant increase in overall photoelectric conversion efficiency. Attached Figure Description

[0034] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0035] Figure 1 The absorption spectra of the i-IEDTB compound solution and the thin film in embodiments of the present invention are shown.

[0036] Figure 2 The HOMO and LUMO energy levels of compound i-IEDTB in this embodiment of the invention;

[0037] Figure 3 The current-voltage curves of the Z10:Y6 photovoltaic device with i-IEDTB as the acceptor are shown.

[0038] Figure 4 The current-voltage curves of the Z10:Y6 photovoltaic device with i-IEDTB as the donor are shown.

[0039] Figure 5 Current-voltage curves of PM6:i-IEDTB photovoltaic devices with i-IEDTB as donor or acceptor;

[0040] Figure 6 Current-voltage curves of PM6:L8-BO photovoltaic devices with i-IEDTB as donor or acceptor. Detailed Implementation

[0041] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0042] This invention develops a small-molecule bifunctional material with a twisted main chain and a wide bandgap, exhibiting hole mobility superior to electron mobility and a high LUMO energy level. Furthermore, the twisted structure allows for tuning of the crystallinity of the active layer, significantly reducing excessive aggregation of donors or acceptors, and promoting a coordinated distribution of electron and hole mobility, thereby enhancing V0. OC Simultaneous improvement with FF. The organic small molecule involved in this invention serves as a bifunctional material. In the active layer of an organic solar cell, it can be added as either an electron acceptor or electron donor material in a specific ratio, resulting in device performance superior to corresponding binary devices. This bifunctional molecule is prevalent in Z10:Y6, PM6:BTP-eC9, and PM6:L8-BO systems, playing a crucial role in regulating crystal arrangement and carrier balance in the active layer of photovoltaic devices, thereby improving the overall performance of organic solar cells.

[0043] This invention provides an organic small molecule semiconductor bifunctional material with the following general formula:

[0044]

[0045] In the formula, R1 is independently an alkyl, alkyl or alkoxy-substituted phenyl, alkyl or alkoxy-substituted thiophene group with 1 to 20 carbon atoms, R2 is independently a hydrogen atom, alkyl, or alkoxy group, R3 is a straight-chain or branched alkyl group with 1 to 12 carbon atoms, and X is independently an O, S, or Se atom. As a bifunctional material for photoactive layer, it is used in the preparation of organic photovoltaic cells to improve device performance.

[0046] For example, R2 is an alkoxy group with 1 to 20 carbon atoms.

[0047] For example, R2 is an alkyl group with 1 to 20 carbon atoms.

[0048] The organic small molecule semiconductor bifunctional material provided by this invention, as a photoactive layer bifunctional material, effectively regulates the crystallinity of the material in the Z10:Y6 active layer system, reduces excessive aggregation of acceptors, promotes the coordinated distribution of electron and hole mobility, and significantly improves the open circuit voltage and fill factor, thereby comprehensively enhancing the device performance of organic photovoltaic cells.

[0049] The organic small molecule semiconductor bifunctional material provided by this invention, as a photoactive layer bifunctional material, effectively regulates the crystallinity of the material in the PM6:BTP-eC9 active layer system, reduces excessive aggregation of acceptors, promotes the coordinated distribution of electron and hole mobility, and significantly improves the open circuit voltage and fill factor, thereby comprehensively enhancing the device performance of organic photovoltaic cells.

[0050] The organic small molecule semiconductor bifunctional material provided by this invention, as a photoactive layer bifunctional material, effectively regulates the crystallinity of the material in the PM6:L8-BO active layer system, reduces excessive aggregation of acceptors, promotes the coordinated distribution of electron and hole mobility, and significantly improves the open circuit voltage and fill factor, thereby comprehensively enhancing the device performance of organic photovoltaic cells.

[0051] The device structure adopted is ITO / PEDOT:PSS / active layer / PDINO / Al type. The wide-bandgap electron donor polymers in the active layer material include DA-type binary or ternary polymer donors based on bisfluorobenzotriazole, benzo[1,2-b:4,5-b']dithiophene, and benzo[1,2-C:4,5-C']dithiophene-4,8-dione, with the following structures:

[0052]

[0053] Electron acceptor materials in the active layer include A-DA'DA type Y6, L8-BO, BTP-eC9, etc., with the following structures:

[0054]

[0055] Example 1: Bifunctional organic semiconductor material i-IEDTB and its application in organic solar energy devices based on the Z10:Y6 system.

[0056] (1) The synthetic route of compound i-IEDTB is as follows:

[0057]

[0058] Scheme 1 Synthetic route of compound i-IEDTB

[0059] Take 2.96 g of the above compound 1 and 2.80 g of compound 5-bromo-4-(2-ethylhexyloxy)-thiophene-3-aldehyde (compound 2), place them in a 250 ml three-necked flask, dissolve them in 160 ml of toluene, under nitrogen protection, add 240 mg of catalyst Pd(PPh3)4, heat at 90 °C overnight, stop heating, cool, remove solvent by rotary evaporation, then add 50 ml of water, extract with ethyl acetate (50 ml for three extractions), combine the organic phases, add anhydrous magnesium sulfate and dry for 2 hours, filter to remove the drying agent, purify the obtained product by column chromatography using 200-300 mesh silica gel column, eluent of ethyl acetate:n-hexane (volume ratio 1:100), to obtain 2.90 g of red solid compound 3; 1 H NMR (500MHz, CDCl3), δ (ppm): 9.93 (s, 2H), 7.42 (s, 2H), 7.25 (s, 2H), 7.16 (d, 8H), 7.09 (d, 8H), 6.86 (s, 2H),4.05(d,4H),2.57(t,8H),1.76(m,2H),1.60-1.42(m,16H),1.34-1.27(m,32H),0.95-0.86(m,24H). 13 C NMR (125MHz, CDCl3), δ (ppm): 180.27, 164.75, 157.21, 153.90, 146.63, 143.03, 141.95, 141.10, 139.11, 135.25, 128.54, 127.80, 121. 81,119.34,117.78,111.20,74.53,63.15,39.52,35.58,31.73,31.35,30.41,29.15,29.03,23.82,22.99,22.60,14.10,14.06,11.14.

[0060] 120 mg of compound 3 and 85 mg of 1,3-diethyl-2-thiophenthionone dihydropyrimidine-4,6(1-H,5-H)-dione were dissolved in 15 mL of chloroform. 0.4 mL of pyridine was added, and the mixture was heated to 65 °C and stirred for 6 hours. After cooling, 20 mL of water was added, and the mixture was extracted with chloroform. The organic phase was dried over anhydrous magnesium sulfate, concentrated, and precipitated in methanol. The solid was then filtered. The product was further purified by column chromatography using 200-300 mesh silica gel with chloroform as the eluent, yielding 120 mg of a black solid in 80.8% yield. 1H NMR(500MHz, CDCl3), δ8.94(s,2H),7.52(s,2H),7.47(s,2H),7.17(d,8H),7.11(d,8H),6.91(s,2H),4.59( m,8H),4.12(m,4H),2.58(t,8H),1.87(m,2H),1.61-1.55(m,16H),1.35-1.30(m,44H),0.99-0.86(m,24H). 13 C NMR (125MHz, CDCl3), δ178.77,169.44,161.43,160.67,158.17,154.48,154.35, 145.23,143.42,142.11,140.77,139.33,135.56,128.63,127.80,123.59,118.1 1,117.46,109.49,105.72,75.20,63.19,43.77,42.93,39.35,35.58,31.72,31.34,30.41,29.11,29.02,23.88,22.97,22.60,14.10,14.05,12.59,12.43,11.07.

[0061] Figure 1 The absorption spectra of the i-IEDTB compound solution and thin film in this embodiment of the invention are shown. It has strong absorption in the 500-700 nm range, which can be used for matching the photoactive layer with the donor or acceptor, which is beneficial to absorbing more sunlight. At the same time, the absorption of the thin film shows a red shift relative to the absorption of the solution, indicating that the material has good stacking in the thin film state, which is beneficial to the morphological stability of the active layer.

[0062] Figure 2 The HOMO and LUMO energy levels of compound i-IEDTB in this embodiment of the invention are shown. Electrochemical cyclic voltammetry was used to measure the oxidation / reduction potentials, which were 0.75V / -1.09V, and the corresponding molecular LUMO / HOMO energy levels were calculated to be -3.62 / -5.46eV. This structure has suitable energy levels and can be used as a photoactive layer material.

[0063] (2) Compound i-IEDTB was used to prepare organic photovoltaic devices in the Z10:Y6 system:

[0064] The device structure uses ITO / PEDOT:PSS / active layer / PDINO / Al. PEDOT:PSS is spin-coated onto ITO glass and then baked at 150℃ for 15 min. Donor polymer Z10 and acceptor material Y6 are dissolved in chloroform at appropriate ratios, with the Z10 concentration controlled at 7 mg / ml. Different ratios of the bifunctional molecule i-IEDTB added to Z10:Y6 are controlled, using i-IEDTB as the acceptor material. Under the condition that the mass ratio of donor Z10 is fixed at 1, the ratio of Y6:i- The mass ratios of i-IEDTB were 1.15:0.05 and 1.1:0.10. Using i-IEDTB as the donor material and immobilizing acceptor Y6 at a mass ratio of 1.2, the mass ratios of Z10:i-IEDTB were selected as 0.95:0.05 and 0.90:0.10. The mixture was then spin-coated at 3000 rpm to a thickness of 90 nm. The active layer was annealed at 90 °C for 10 min, followed by spin-coating of a PDINO layer. Finally, a 100 nm aluminum layer was deposited under vacuum, with an effective area of ​​0.039 cm². 2 Then, the device performance was tested, and the current density (J)-voltage (V) curve and EQE were obtained. Finally, the device PCE was calculated. The device performance under the relevant testing conditions is shown in Table 1. Figure 3 and 4 As shown.

[0065] Table 1 shows the performance of i-IEDTB in organic solar cell devices with Z10:Y6 active layer.

[0066]

[0067]

[0068] a) The data consists of the average value and deviation of 10 devices.

[0069] Table 1 and Figure 3 As can be seen, when i-IEDTB is used as the acceptor material in a Z10:Y6 photovoltaic device, the open-circuit voltage V is [value missing] when the addition ratio Z10:(Y6:i-IEDTB) = 1:1.15:0.05. OC Reaching 0.849V, short-circuit current density J SC Slightly decreased by 26.79 mA cm -2 The fill factor FF was increased to 78.02%, and the photoelectric conversion efficiency was increased to 17.70%. When the addition ratio Z10:(Y6:i-IEDTB)=1:1.1:0.1, V OC =0.861V, J SC =26.66mA cm -2 With an FF of 79.91%, the photoelectric conversion efficiency was improved to 17.61%, and the device performance was significantly improved.

[0070] Table 1 and Figure 4 The results show that when i-IEDTB is used as a donor material in a Z10:Y6 photovoltaic device, the V0 is significantly increased when the addition ratio (Z10:i-IEDTB):Y6 = 0.95:0.05:1.2. OC =0.846V, J SC =26.43mA cm -2 FF = 78.08%, photoelectric conversion efficiency increased to 17.47%. When the addition ratio (Z10:i-IEDTB):Y6 = 0.9:0.1:1.2, V OC =0.85V, J SC =26.24mA cm -2 With an FF of 76.37%, the photoelectric conversion efficiency was improved to 17.03%, showing a significant improvement in performance compared to the Z10:Y6 device.

[0071] Example 2: Bifunctional organic semiconductor material i-IEDTB and its application in organic solar energy devices of PM6:BTP-eC9 system.

[0072] The device structure adopts ITO / PEDOT:PSS / active layer / PDINO / Al. PEDOT:PSS is spin-coated onto ITO glass and then baked at 150℃ for 15 min. The donor polymer PM6 and the acceptor material BTP-eC9 are dissolved in chloroform in a corresponding ratio, and the PM6 concentration is controlled at 7 mg / ml. The different ratios of the bifunctional molecule i-IEDTB added to PM6:BTP-eC9 are also controlled. Using i-IEDTB as the acceptor material, with a fixed donor PM6 mass ratio of 1, the i-IEDTB:BTP-eC9 mass ratio was selected as 1.15:0.05; using i-IEDTB as the acceptor material, with a fixed acceptor BTP-eC9 mass ratio of 1.2, the PM6:i-IEDTB mass ratio was selected as 0.95:0.05. The mixture was then spin-coated at 3000 rpm to a thickness of 90 nm. The active layer was annealed at 90 °C for 10 min, followed by spin-coating of a PDINO layer. Finally, a 100 nm aluminum layer was deposited under vacuum, resulting in an effective area of ​​0.039 cm². 2 Then, the device performance was tested, and the current density (J)-voltage (V) curve and EQE were obtained. Finally, the device PCE was calculated. The relevant device performance is shown in Table 2. Figure 5 As shown.

[0073] Table 2 shows the performance of i-IEDTB in organic solar energy devices using PM6:BTP-eC9 active layer system.

[0074]

[0075]

[0076] a) The data consists of the average value and deviation of 10 devices.

[0077] From Table 2 and Figure 5 The results show that when i-IEDTB is used as a donor material in PM6:BTP-eC9 photovoltaic devices, the open-circuit voltage V0 is [value missing]. When the addition ratio (PM6:i-IEDTB:BTP-eC9) = 0.95:0.05:1.2, [value missing]. OC Reaching 0.838V, short-circuit current density J SC Slightly decreased by 27.99 mA cm -2 The fill factor FF was increased to 75.22%, the photoelectric conversion efficiency was improved to 17.62%, and the overall device performance was enhanced. When i-IEDTB is used as the acceptor material in PM6:BTP-eC9 photovoltaic devices, the open-circuit voltage V is improved when the addition ratio PM6:(BTP-eC9:i-IEDTB) = 1:1.15:0.05. OC Reaching 0.84V, short-circuit current density J SC Increased to 28.27 mA cm -2 The fill factor FF was increased to 76.47%, the photoelectric conversion efficiency was increased to 18.14%, and the device performance was improved across the board.

[0078] Example 3: Bifunctional organic semiconductor material compound i-IEDTB and its application in organic solar energy devices of PM6:L8-BO system.

[0079] The device structure uses ITO / PEDOT:PSS / active layer / PDINO / Al. PEDOT:PSS is spin-coated onto ITO glass and then baked at 150℃ for 15 min. The donor polymer PM6 and acceptor material L8-BO are dissolved in chloroform at appropriate ratios, with the PM6 concentration controlled at 7 mg / ml. Different ratios of the bifunctional molecule i-IEDTB added to PM6:L8-BO are controlled, using i-IEDTB as the acceptor material, with a fixed mass ratio of PM6 to donor. Under the following conditions, the mass ratio of i-IEDTB to L8-BO was selected as 1.15:0.05; using i-IEDTB as the donor material and the mass ratio of L8-BO to the immobilizer was 1.2, the mass ratio of PM6 to i-IEDTB was selected as 0.95:0.05; then the mixture was spin-coated at 3000 rpm to a thickness of 90 nm, the active layer was annealed at 90 °C for 10 min, then a PDINO layer was spin-coated, and finally a 100 nm aluminum layer was deposited under vacuum, with an effective area of ​​0.039 cm². 2Then, the device performance was tested, and the current density (J)-voltage (V) curve and EQE were obtained. Finally, the device PCE was calculated. The relevant device performance is shown in Table 3. Figure 6 As shown.

[0080] Table 3 shows the performance of i-IEDTB in organic solar energy devices with PM6:L8-BO active layer.

[0081]

[0082]

[0083] a) The data consists of the average value and deviation of 10 devices.

[0084] From Table 3 and Figure 6 As can be seen, when i-IEDTB is used as a donor material in a PM6:L8-BO photovoltaic device, the open-circuit voltage V of the device is [value missing] when the addition ratio (PM6:i-IEDTB):L8-BO = 0.95:0.05:1.2. OC Reaching 0.883V, short-circuit current density J SC Rising to 26.14 mA cm -2 The fill factor FF is 78.35%, the photoelectric conversion efficiency is improved to 18.06%, and all performance indicators of the photovoltaic device are improved. i-IEDTB is used as the acceptor material in PM6:L8-BO photovoltaic devices. When the addition ratio PM6:(L8-BO:i-IEDTB)=1:1.15:0.05, the open-circuit voltage V of the device is... OC Reaching 0.877V, short-circuit current density J SC Rising to 26.20 mAcm -2 The fill factor FF is 78.63%, and the photoelectric conversion efficiency is improved to 18.08%. Compared with PM6:L8-BO binary photovoltaic devices, all performance indicators are improved.

[0085] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. An organic small molecule semiconductor bifunctional material, characterized in that, The structure of the material is shown in Formula I: Formula I; In the formula, R1 is a phenyl group substituted with alkyl or alkoxy groups; R2 is a hydrogen atom, an alkyl group, or an alkoxy group; R3 is a straight-chain or branched alkyl group having 1 to 12 carbon atoms; X is an S atom.

2. The organic small molecule semiconductor bifunctional material as described in claim 1, characterized in that, R2 is an alkoxy group having 1 to 20 carbon atoms.

3. The organic small molecule semiconductor bifunctional material as described in claim 1 or 2, characterized in that, R2 is an alkyl group having 1 to 20 carbon atoms.

4. The organic small molecule semiconductor bifunctional material as described in claim 1 or 2, characterized in that, The structure of the material is shown below: 。 5. The application of the organic small molecule semiconductor bifunctional material according to any one of claims 1-4 as an electron donor or electron acceptor in the photoactive layer material of organic photovoltaic cells.

6. The application according to claim 5, characterized in that, The active layer of the photoactive layer material is a Z10:Y6 mass ratio system of 1:1.2, where Z10 is the donor and Y6 is the acceptor; When organic small molecule semiconductor bifunctional material is incorporated into Y6 as an acceptor, the mass ratio of organic small molecule semiconductor bifunctional material to Y6 acceptor is 1:(11-23). When organic small molecule semiconductor bifunctional material is incorporated into Z10 as a donor, the mass ratio of organic small molecule semiconductor bifunctional material to Z10 donor is 1:(9~19).

7. The application according to claim 5, characterized in that, The active layer of the photoactive layer material is a PM6:BTP-eC9 mass ratio system of 1:1.2, where PM6 is the donor and BTP-eC9 is the acceptor. When organic small molecule semiconductor bifunctional material is incorporated into BTP-eC9 as an acceptor, the mass ratio of organic small molecule semiconductor bifunctional material to BTP-eC9 acceptor is 1: (11-23). When organic small molecule semiconductor bifunctional materials are incorporated into PM6 as donors, the mass ratio of organic small molecule semiconductor bifunctional materials to PM6 donors is 1:(9-19).

8. The application according to claim 5, characterized in that, The active layer of the photoactive layer material is a PM6:L8-BO mass ratio system of 1:1.2, where PM6 is the donor and L8-BO is the acceptor. When organic small molecule semiconductor bifunctional material is incorporated into L8-BO as an acceptor, the mass ratio of organic small molecule semiconductor bifunctional material to L8-BO acceptor is 1:(11~23). When organic small molecule semiconductor bifunctional materials are incorporated into PM6 as donors, the mass ratio of organic small molecule semiconductor bifunctional materials to PM6 donors is 1:(9-19).

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