Aromatic ring expanded dithiazole fully non-condensed ring polymer, preparation method thereof and application of aromatic ring expanded dithiazole fully non-condensed ring polymer to photoelectric device

Abstract

The invention discloses a dithiazole fully non-fused ring polymer with an expanded aromatic ring. The dithiazole fully non-fused ring polymer has a dithiazole structure with an expanded aromatic ring core Ar; the structural formula is more than one of the following structural formulas: in the # imgabs0 # formula, R is one of alkyl of C1 to C30, alkoxy of C1 to C30, ester group of C1 to C30 or sulfydryl; d is selected from one of thiophene, selenophen and bithiophene or a corresponding halogen substituent group; the electron-deficient unit core Ar is selected from one of thiophene, selenophen, benzene ring and pyrazine; the value of n ranges from 10 to 100. According to the invention, dithiazole with an expanded aromatic ring core is used as a unit A, and is combined with a unit D for collaborative optimization to construct the wide-band-gap fully non-fused polymeric material with relatively deep energy level distribution and relatively strong light absorption intensity; the material can be matched with different types of donor and acceptor materials, devices with wide absorption wave band coverage can be prepared, and high-efficiency photoelectric devices can be obtained on the basis of reducing the cost.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic optoelectronic materials and devices, and particularly relates to an aromatic ring-expanded dithiazole all non-fused-ring polymer, a preparation method thereof, and an application thereof in optoelectronic devices. Background Art

[0002] With the aggravation of problems such as the greenhouse effect and environmental pollution, the development of clean energy has become the focus of human attention. New energy sources such as solar energy, hydraulic energy, wind energy, geothermal energy, and tidal energy are considered to be necessary boosters for high-quality economic development due to their characteristics of being renewable and having low emissions (or zero emissions). Among them, the photovoltaic effect of photovoltaic energy is to convert solar radiant energy into electrical energy, which has the advantages of being pollution-free, noiseless, low maintenance cost, and long service life, and has developed rapidly in recent years. Among them, organic solar cells (OSCs) are expected to be widely used in various scenarios due to their advantages of low cost, flexibility, and portability.

[0003] In recent years, the development of non-fullerene small molecule acceptor materials has lifted the efficiency of battery devices to a new height (exceeding 20%). The absorption spectrum width of non-fullerene small molecule acceptor materials can be extended to the near-infrared region (about 1000 nm), and excitons can be efficiently separated to generate charges even under a low charge separation driving force; it can effectively broaden the research scope of polymer donor materials that match them, and has become the key to further improving the efficiency of organic solar cells. In the battery devices that have shown high performance, polymer donor materials mostly have a fused-ring structure, which inevitably increases the synthesis and purification steps, resulting in an increase in cost and being unfavorable for industrial application. Therefore, constructing high-efficiency and low-cost polymer donor materials is the focus of current research.

[0004] From the perspective of cost, polythiophene has a simple structure, is easy to synthesize, and has cheap raw material sources, and is one of the most suitable candidate materials for large-scale production in the field of organic optoelectronics. However, in non-fullerene OSCs, due to the inability to form a matching energy level and an ideal active layer morphology between polythiophene (PTs) and non-fullerene acceptors, the power conversion efficiency (PCE) of polythiophene solar cells still lags behind that of donor-acceptor type conjugated polymers. Given its cost advantage, further optimizing its structure to improve device efficiency is of great significance for the development of organic solar cells. Summary of the Invention

[0005] The main object of the present invention is to provide, in view of the deficiencies of the prior art, an aromatic-ring-expanded dithiazole all non-fused-ring polymer. By using dithiazole expanded with an aromatic-ring core as the A unit, the molecular planarity is effectively increased. At the same time, multiple non-covalent bonds can be formed between the aromatic-ring substituents and the thiazole ring, inhibiting the rotation of single bonds and further increasing the planarity of the backbone. Further combined with the synergistic optimization of the D unit, a fully non-fused polymeric material with a deeper energy level distribution and stronger light absorption intensity is constructed, obtaining a better absorption range and morphology (such as roughness) while suppressing energy loss.

[0006] Another object of the present invention is to provide the application of the above-mentioned all non-fused-ring polymer donor material in optoelectronic devices. Further combined with suitable donor-acceptor materials, binary or ternary devices are prepared and applied in organic solar cells to achieve the preparation of low-cost and high-efficiency battery devices.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] An aromatic-ring-expanded dithiazole all non-fused-ring polymer, which comprises an electron-deficient unit (A unit) with a symmetric structure, and the electron-deficient unit has a dithiazole structure expanded with an aromatic-ring core Ar; the structural formula of the polymer is one or more of those shown in Formula 1:

[0009]

[0010] In the formula, R is one of an alkyl group with C1 - C 30 an alkoxy group with C1 - C 30 an ester group with C1 - C 30 or a mercapto group; D is selected from one of thiophene, selenophene, bithiophene, or the corresponding halogen-substituted group; the electron-deficient unit core Ar is selected from one of thiophene, selenophene, benzene ring, pyrazine; n ranges from 10 to 100.

[0011] Furthermore, the halogen group used for the halogen substitution is one or more of F and Cl.

[0012] Preferably, in the substituent R, the number of carbons is preferably C6 - C 20 . By optimizing the alkyl chain, a polymer material with a lower HOMO energy level can be obtained on the premise of ensuring sufficient solubility, suppressing energy loss, and obtaining a high open-circuit voltage.

[0013] Furthermore, for the thiazole substituent R, introducing an alkyl chain increases the steric hindrance effect and prevents the twisting of the main chain; the introduction of an alkoxy group, an ester group, or a mercapto group can cause non-covalent interactions between the heteroatom and S, N, etc. on the thiazole unit, further forming a conformational lock and promoting the main chain to be more flat.

[0014] In the above solution, the molecular weight range of the polymer is 20,000 - 600,000.

[0015] In the above solution, the structural formula of the aromatic ring core Ar is specifically one of those in Formula 2:

[0016]

[0017] Furthermore, the D unit is specifically selected from the following structures:

[0018]

[0019] The preparation method of the above-mentioned aromatic ring-expanded dithiazole all non-fused ring polymer includes the following steps:

[0020] Under catalytic conditions, subject the halogenated electron-deficient (A) unit monomer and the dimethyltin D unit monomer to Stille polymerization, and then perform extraction to obtain the all non-fused ring polymer.

[0021] In the above solution, the structural formula of the halogenated electron-deficient unit monomer is one of those in Formula 4;

[0022]

[0023] In the formula, R is taken from one of C1-C 30 alkyl, alkoxy, ester group or mercapto group.

[0024] In the above solution, the structural formula of the dimethyltin D unit monomer is shown in Formula 5;

[0025]

[0026] In the formula, X is H or a halogen atom (F or Cl); D is selected from thiophene, selenophene or bithiophene.

[0027] In the above solution, the reaction solvent used for the Stille polymerization is toluene or o-xylene, the reaction temperature is 100-140 °C, and the time is 1-12 h.

[0028] In the above solution, the extraction process includes: successively extract with methanol, acetone, n-hexane, dichloromethane and chloroform, and finally collect the chloroform phase.

[0029] In the above solution, the catalyst is a palladium catalyst, and specifically, tetrakis(triphenylphosphine)palladium or tris(dibenzylideneacetone)dipalladium etc. can be selected.

[0030] In the above solution, the preparation method of the halogenated electron-deficient unit monomer includes the following steps:

[0031] (1) For the A units corresponding to the first two structural formulas in Formula 1, the preparation method of the halogenated electron-deficient unit monomer includes the following steps:

[0032] 1) Using the 4-position substituted bromothiazole as a raw material, an alkylation reaction is carried out to generate Compound 1; then it is coupled with the Ar core unit substituted with dibutyltin to generate Compound 2;

[0033] 2) Under low temperature and organolithium reagent conditions, Compound 2 is subjected to a bromination reaction with 1,2-dibromotetrachloroethane to generate Compound 3, which is the corresponding halogenated electron-deficient unit monomer;

[0034] (2) For the remaining two structural formula corresponding A units in Formula 1, the preparation method of the halogenated electron-deficient unit includes the following steps:

[0035] 3) Compound 3 is coupled with 2-tributylstannylthiophene to generate Compound 4; then a bromination reaction is carried out to generate Compound 5, which is the corresponding halogenated electron-deficient unit monomer.

[0036] In the above scheme, the general formula of the 4-position substituted bromothiazole is one of those in Formula 6;

[0037]

[0038] In the formula, R1 is taken from one of bromine, methoxy, methyl ester, and mercapto.

[0039] In the above scheme, the general formula of Compound 1 is one of those in Formula 7;

[0040]

[0041] In the formula, R is taken from one of C1 - C 30 alkyl, alkoxy, ester group, and mercapto.

[0042] In the above scheme, the general formula of Compound 2 is one of those in Formula 8;

[0043]

[0044] In the formula, R is taken from one of C1 - C 30 alkyl, alkoxy, ester group, or mercapto.

[0045] In the above scheme, the general formula of Compound 3 is one of those in Formula 9;

[0046]

[0047] In the above scheme, the general formula of Compound 4 is one of those in Formula 10;

[0048]

[0049] In the formula, R is taken from one of C1 - C 30 alkyl, alkoxy, ester group, or mercapto.

[0050] In the above scheme, except for the alkylation reaction in step 1) and the bromination reaction in step 3), the remaining conditions are anhydrous and anaerobic conditions; the protective atmosphere can be an inert atmosphere such as nitrogen or argon.

[0051] In the above scheme, the temperature used in the alkylation reaction described in step 1) is 80 - 120 °C, and the reaction time is 6 - 36 h.

[0052] In the above scheme, the low - temperature conditions used in the reaction (bromination reaction) described in step 2) are - 80 to - 70 °C or 0 to 10 °C, and the reaction time is 2 - 24 h; the organolithium reagent is n - butyllithium or lithium bis(trimethylsilyl)amide.

[0053] In the above scheme, the temperature used in the coupling reaction described in step 1) and step 3) is 100 - 130 °C, and the reaction time is 3 - 24 h.

[0054] The aryl - extended dithiazole all - non - fused - ring polymer prepared according to the above scheme is a wide - bandgap material (> 1.8 eV).

[0055] The present invention provides an application of the above aryl - extended dithiazole all - non - fused - ring polymer as an active - layer material in optoelectronic devices.

[0056] Furthermore, the aryl - extended dithiazole all - non - fused - ring polymer, as a wide - bandgap donor material, is blended with a medium - bandgap donor material and a narrow - bandgap acceptor material, which can cover a relatively wide light absorption range, ensure the full utilization of light by the thin film, and obtain a relatively high short - circuit current.

[0057] Furthermore, the narrow - bandgap acceptor material can be selected from one or more of acceptor materials such as Y6, L8 - BO, etc.; the medium - bandgap donor material can be selected from one or more of polymeric materials such as PM6, PBDB - BzT, PBT - Cl, etc.

[0058] Furthermore, the mass ratio of the aryl - extended dithiazole all - non - fused - ring polymer to the sum of the medium - bandgap donor material and the narrow - bandgap acceptor material is 1:(1 - 1.5).

[0059] Furthermore, the mass ratio of the aryl - extended dithiazole all - non - fused - ring polymer to the medium - bandgap donor material is (1 - 95):1.

[0060] Specifically, the optoelectronic device is an organic solar cell, a perovskite solar cell, an organic light - emitting diode, an organic detector, etc.

[0061] Furthermore, the PCE of the prepared double - donor ternary organic solar cell is as high as 18.12%.

[0062] Compared with the prior art, the beneficial effects of the present invention include:

[0063] 1) The designed electron-deficient unit structure in the all non-fused-ring polymer material of the present invention is simple, easy to prepare, and low in cost. At the same time, it has multiple modification sites, is easy to optimize, and can be designed to obtain the required high-performance polymer materials.

[0064] 2) The present invention first proposes to use arene-core-expanded dithiazole as the A unit, which effectively increases the molecular planarity. At the same time, the arene substituents and the thiazole ring can form multiple non-covalent bonds to inhibit the rotation of single bonds, further increasing the planarity of the backbone. By combining with the D unit, a broadband-gap all non-fused polymer material with a relatively deep energy level distribution and strong light absorption intensity is synergistically optimized and constructed.

[0065] 3) The aryl-expanded dithiazole all non-fused-ring polymer designed in the present invention, as a broadband-gap material, can be matched with many different types of donor-acceptor materials to prepare ternary devices with a relatively wide absorption band coverage, which are applied to optoelectronic device fields such as organic solar cells and perovskite solar cells, realizing the achievement of high-efficiency optoelectronic devices while reducing costs. Description of the Drawings

[0066] Figure 1 It is the ultraviolet-visible absorption spectrum of the polymer PTZ2E-BT2F obtained in the present invention in chloroform solution (room temperature) and in the thin film state.

[0067] Figure 2 It is the ultraviolet-visible absorption spectrum diagram of the polymer PTZ2E-BT2F obtained in the present invention and the fused-ring acceptor L8-BO in the thin film state.

[0068] Figure 3 It is the energy level distribution diagram of the polymer PTZ2E-BT2F obtained in the present invention, the polymer PZ2E-BT2F obtained in Comparative Example 1, the polymer donor PM6, and the fused-ring acceptors L8-BO and Y6.

[0069] Figure 4 It is the J-V curve diagram of the binary organic solar cell prepared by blending the polymer PTZ2E-BT2F obtained in the present invention and the fused-ring acceptor L8-BO.

[0070] Figure 5 It is the AFM diagram of the blend film prepared by blending the polymer PTZ2E-BT2F obtained in the present invention and the fused-ring acceptor L8-BO.

[0071] Figure 6 It is the ultraviolet-visible absorption spectrum diagram of the polymer PTZ2E-BT2F obtained in the present invention, the polymer donor PM6, and the fused-ring acceptor Y6 in the thin film state.

[0072] Figure 7The J-V curve diagram of a ternary organic solar cell prepared by blending the polymer PTZ2E-BT2F obtained in the present invention with the polymer donor PM6 and the fused-ring acceptor Y6.

[0073] Figure 8 The UV-visible absorption spectra of the polymer PZ2E-BT2F obtained in Comparative Example 1 in chloroform solution (room temperature) and in thin film state.

[0074] Figure 9 The UV-visible absorption spectrum diagram of the polymer PZ2E-BT2F obtained in Comparative Example 1 and the fused-ring acceptor L8-BO in thin film state.

[0075] Figure 10 The J-V curve diagram of a binary organic solar cell prepared by blending the polymer PZ2E-BT2F obtained in Comparative Example 1 with the fused-ring acceptor L8-BO.

[0076] Figure 11 The AFM diagram of the blend film prepared by blending the polymer PZ2E-BT2F obtained in Comparative Example 1 with the fused-ring acceptor L8-BO. Detailed Description of the Invention

[0077] The technical solutions adopted in the present invention are described in detail below through specific implementation examples. What is described is only a part of the present invention and does not represent all embodiments. Unless otherwise specified, the experimental methods adopted in the present invention are all conventional methods, and the instrument equipment adopted are all commercial products in this technical field.

[0078] Example 1

[0079] A class of dithiazole fully non-fused-ring polymer materials with a thiophene core extension. Among them, the synthesis route of the electron-deficient core unit monomer 2,5-bis(thiazol-2-yl)thiophene is shown in Formula 11;

[0080]

[0081] The specific preparation steps are as follows:

[0082] 1) Dissolve methyl 2-bromothiazole-4-carboxylate (3.11 g, 14 mmol), p-toluenesulfonic acid (2.41 g, 14 mmol), and 2-decyl-1-tetradecanol (6.21 g, 17.5 mmol) in 60 mL of toluene, heat to 120 °C and react for 8 h. Then add saturated brine, extract with dichloromethane, dry the organic phase with anhydrous sodium sulfate, remove the solvent by rotary evaporation, and perform column chromatography on the crude product using a mixed solvent of petroleum ether and ethyl acetate (the volume ratio of the two is 15:1) as the eluent to obtain a light brown transparent oily liquid compound 1 (5.6 g, yield 73.4%). 11H NMR (400 MHz, CDCl3), δ (ppm): 8.05 (s, 1H), 4.25 (d, J = 6.5 Hz, 2H), 1.78 (m, 1H), 1.24 (m, 40H), 0.87 (t, J = 6.5 Hz, 6H);

[0083] 2) Under a nitrogen atmosphere, compound 1 (5.45 g, 10 mmol), 2,5-bis(tri-n-butylstannyl)thiophene (2.22 g, 3.33 mmol), and tetrakis(triphenylphosphine)palladium (0.69 g, 0.6 mmol) were dissolved in 50 mL of anhydrous N,N-dimethylformamide and reacted at 120 °C for 9 h. Then, saturated brine was added, and the mixture was extracted with dichloromethane. The organic phase was washed several times with deionized water, collected and combined, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The crude product was subjected to column chromatography using a mixed solvent of petroleum ether and ethyl acetate (volume ratio 10:1) as the eluent to obtain a yellow transparent oily liquid, compound 2 (2.2 g, yield 65.2%). 1 1H NMR (400 MHz, CDCl3), δ (ppm): 8.07 (s, 2H), 7.58 (s, 2H), 4.26 (d, J = 5.8 Hz, 4H), 1.80 (m, 2H), 1.25 (m, 80H), 0.86 (t, J = 6.5 Hz, 12H);

[0084] 3) Under a nitrogen atmosphere, compound 2 (2.02 g, 2 mmol) and 1,2-dibromotetrachloroethane (1.63 g, 5 mmol) were dissolved in 40 mL of anhydrous tetrahydrofuran. Under ice bath conditions, a solution of lithium bis(trimethylsilyl)amide (6 mL, 6 mmol) was added dropwise, and the reaction was continued under ice bath for 2 h. Then, the reaction was quenched by adding distilled water, and the mixture was extracted with dichloromethane. The organic phase was dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The crude product was subjected to column chromatography using a mixed solvent of petroleum ether and dichloromethane (volume ratio 1:1) as the eluent to obtain a yellow transparent oily liquid, compound 3 (1.5 g, yield 64.1%). 1 1H NMR (400 MHz, CDCl3), δ (ppm): 7.48 (s, 2H), 4.29 (d, J = 6.0 Hz, 4H), 1.82 (m, 2H), 1.26 (m, 80H), 0.86 (t, J = 6.5 Hz, 12H);

[0085] 4) Under a nitrogen atmosphere, compound 3 (1.20 g, 1 mmol), 2-tributylstannylthiophene (1.14 g, 3 mmol), and tetrakis(triphenylphosphine)palladium (0.083 g, 0.07 mmol) were dissolved in 15 mL of anhydrous N,N-dimethylformamide and heated at 120 °C for 9 h. Then, the reaction was quenched by adding distilled water, and the mixture was extracted with dichloromethane. The organic phase was washed several times with deionized water, collected and combined, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The crude product was purified by column chromatography using a mixed solvent of petroleum ether and dichloromethane (volume ratio 1:1) as the eluent to obtain a yellowish-green transparent oily liquid compound 4 (0.83 g, yield 70.1%). 1 H NMR (400 MHz, CDCl3), δ (ppm): 7.53 (s, 2H), 7.47 (d, J = 4.2 Hz, 4H), 7.09 (t, J = 4.4 Hz, 2H), 4.22 (d, J = 6.0 Hz, 4H), 1.72 (m, 2H), 1.25 (m, 80H), 0.86 (t, J = 6.4 Hz, 12H);

[0086] 5) Compound 4 (0.76 g, 0.65 mmol) and N-bromosuccinimide (0.232 g, 1.3 mmol) were dissolved in 8 mL of a mixed solvent (chloroform: glacial acetic acid volume ratio 1:1) and reacted at room temperature for 2 h. Then, saturated sodium bicarbonate aqueous solution was added, and the mixture was extracted with dichloromethane. The organic phase was washed several times with deionized water, collected and combined, dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The crude product was purified by column chromatography using a mixed solvent of petroleum ether and dichloromethane (volume ratio 2:3) as the eluent to obtain a yellow transparent oily liquid compound 5 (0.553 g, yield 75%); 1 H NMR (400 MHz, CDCl3), δ (ppm): 7.52 (s, 2H), 7.21 (d, J = 4.0 Hz, 2H), 7.05 (d, J = 4.0 Hz, 2H), 4.25 (d, J = 6.0 Hz, 4H), 1.76 (m, 2H), 1.23 (m, 80H), 0.86 (t, J = 6.5 Hz, 12H).

[0087] The synthetic route of the thiophene-core extended dithiazole all non-fused ring polymer material is shown in Formula 12:

[0088]

[0089] The specific preparation steps are as follows: Under nitrogen protection, compound 5 (66.53 mg, 0.05 mmol) and 3,4-difluoro-2,5-bis(trimethylstannyl)thiophene (22.40 mg, 0.05 mmol; self-made in the laboratory), the catalyst tetrakis(triphenylphosphine)palladium (2.88 mg, 2.5 μmol) and 1 mL of anhydrous toluene were added in sequence, and the reaction was carried out at 110 °C for 4 h; after the reaction, the crude product was precipitated with methanol, and then extracted with acetone, n-hexane, dichloromethane, and chloroform in sequence. Chloroform was collected, added with methanol for precipitation, and filtered to obtain the final target polymer PT2ZE-BT2F (40.27 mg, yield 63%); the molecular weight of the CF phase was measured to be 17.7 kDa.

[0090] Figure 1 Figure 4 shows the ultraviolet-visible absorption spectra of the polymer PTZ2E-BT2F obtained in this invention in chloroform solution (room temperature) and thin film state. Among them, the solution concentration is 1×10 -5 g / mL; the thin film preparation steps are as follows: The target polymer PTZ2E-BT2F was dissolved in chloroform to prepare a solution with a concentration of 10 mg / mL, and then a thin film with a thickness of 30-100 nm was prepared by a spin coater. As Figure 1 shown, in the solution state, PTZ2E-BT2F shows two characteristic absorption peaks: the short-wavelength absorption peak is at 548 nm, attributed to π-π electron transition; the absorption peak at 597 nm is an aggregation shoulder peak, and its extinction coefficient is slightly lower than that of the short-wavelength absorption peak. In the thin film state, the characteristic peak of the polymer PTZ2E-BT2F is red-shifted by 4 nm compared with the solution state, and at the same time the absorption range becomes wider and the aggregation shoulder peak is higher, indicating that there is stronger π-π stacking in the formed thin film state, which is conducive to obtaining a high carrier mobility. The edge absorption of the polymer PTZ2E-BT2F thin film is 663 nm. According to the formula E g = 1240 / λ, it can be calculated that the band gap E g is 1.87 eV, which is a wide-bandgap polymer.

[0091] The redox process of PTZ2E-BT2F was tested by electrochemical cyclic voltammetry. Using ferrocene as the reference (the vacuum level is -4.8 eV), the initial redox potential corresponding to the target molecule was obtained. The highest occupied molecular orbital level (HOMO) and the lowest unoccupied molecular orbital level (LUMO) of the material can be obtained according to the formula: E HOMO = -(E ox onset - E Fc / Fc+ + 4.8) eV and E LUMO = -(E red onset - E Fc / Fc++4.8) eV. A three - electrode system was adopted. The synthesized polymer PTZ2E - BT2F was made into a chloroform solution with a concentration of 3 mg / mL, and it was dropped onto a glassy carbon electrode to prepare a thin film. Then, the glassy carbon electrode loaded with the thin film was placed in an acetonitrile electrolyte solution containing 0.1 M tetrabutylammonium hexafluorophosphate for testing. The whole testing process required nitrogen protection, and the scanning rate was 0.1 V / s. The standard electrode potential of ferrocene was 0.05 V, and the initial oxidation potential of the polymer PTZ2E - BT2F was 0.89 V. According to the above formula, the HOMO energy level of the polymer PTZ2E - BT2F was calculated to be - 5.41 eV. Since no obvious reduction potential was observed, the LUMO energy level was obtained based on the material's HOMO energy level and the optical band gap difference, which was - 3.51 eV (see Figure 3 ). The relatively deep HOMO energy level of this molecule can be paired with many types of acceptor materials, and the fabricated devices can obtain a relatively high open - circuit voltage.

[0092] The narrow - bandgap acceptor material L8 - BO (the structural formula is shown in Formula 13) was selected and blended with the all - non - fused - ring polymer donor material PTZ2E - BT2F of the present invention. The prepared thin film can cover an absorption range as wide as 450 nm - 910 nm (see Figure 2 ), ensuring the full utilization of light by the thin film. The fabricated binary organic solar cell can obtain a relatively high short - circuit current.

[0093]

[0094] The narrow - band - series acceptor material L8 - BO (the structural formula is shown in Formula 13) was selected and blended with the polymer material PTZ2E - BT2F of the present invention to prepare a thin film. A binary organic solar cell was fabricated, and the forward device structure: ITO / PEDOT:PSS / PZ2E - BT2F:L8 - BO / PDIN / Ag was used to test the photovoltaic performance of the cell. The results are as Figure 4 shown: After optimizing the device fabrication process, the PCE of the cell device was 8.81%, where V oc was 0.904 V, J sc was 16.35 mA / cm 2 , and FF was 59.58%.

[0095] To analyze the reasons for the differences in the carrier dynamics behavior and mobility of the device, the device film structure was analyzed. The test results based on the Atomic Force Microscope (AFM) are as follows. The AFM analysis test results of the surface morphology of the blended thin film are as Figure 5 shown. The obtained PTZ2E - BT2F:L8 - BO blended film reached an R of 1.751 nm qValue. This corresponds to the stronger aggregation ability of PTZ2E-BT2F, which is beneficial to obtaining higher exciton separation efficiency to promote the improvement of device FF and J sc improvement.

[0096] The conjugated polymer PM6 with a medium bandgap (structural formula shown in Equation 14, molecular weight 30 - 65 kDa) and the acceptor material Y6 with a narrow bandgap (structural formula shown in Equation 15) are selected and blended with the fully non-fused-ring polymer donor material PTZ2E-T2F of the present invention. The prepared thin film can cover a wide absorption range from 400 nm to 910 nm (see Figure 6 ), ensuring the full utilization of light by the thin film. The prepared ternary organic solar cells can obtain a relatively high short-circuit current. At the same time, the addition of the polymer PTZ2E-T2F forms a good energy level cascade with the polymer PM6 and the small molecule acceptor Y6 (refer to Figure 3 ), which is beneficial to charge transport.

[0097]

[0098] Furthermore, the polymer material PTZ2E-BT2F of the present invention is added as a third component to the PM6:Y6 mixed thin film to prepare a double-donor ternary organic solar cell. The forward device structure: ITO / PEDOT:PSS / PM6:PTZ2E-BT2F:Y6 / PDIN / Ag is used to test the photovoltaic performance of the battery. The results are as Figure 7 shown. After optimizing the mixing ratio, when the mass ratio of PM6:PTZ2E-BT2F:Y6 is 0.9:0.1:1.2, the PCE of the battery device reaches 18.12%, where V oc is 0.88 V, J sc is 27.02 mA / cm 2 , and FF is 76.21%. Compared with the binary device of PM6:Y6, the higher V oc indicates that the polymer PTZ2E-BT2F and PM6 can form an alloy to lower the HOMO energy level; the increased J sc is mainly due to the enhanced photon capture ability of the ternary device in the range of 400 - 600 nm.

[0099] Example 2

[0100] A polymer PTZ5E-BT2F prepared by copolymerizing a thiophene-expanded 2,5-bis(thiazol-2-yl)thiophene as an electron-deficient unit with (3,3'-difluoro-[2,2'-bithiophene]-5,5'-diyl)bis(trimethylstannane), and its specific synthesis route is shown in Equation 16:

[0101]

[0102] The specific preparation steps are as follows:

[0103] 1) Dissolve methyl 5-bromo-thiazole-4-carboxylate (4.44 g, 20 mmol), p-toluenesulfonic acid (10.3 g, 60 mmol), and 2-decyl-1-tetradecanol (35.4 g, 100 mmol) in 30 mL of toluene, heat to 120 °C and react for 7.5 h. Then add saturated brine, extract with dichloromethane, dry the organic phase with anhydrous sodium sulfate, remove the solvent by rotary evaporation, and perform column chromatography on the crude product using a mixed solvent of petroleum ether and ethyl acetate (volume ratio of the two is 5:1) as the eluent to obtain a pale yellow liquid compound 1 (8.52 g, yield 69.1%). 1 1H NMR (400 MHz, CDCl3), δ (ppm): 8.78 (s, 1H), 4.28 (s, 2H), 1.82 (p, J = 6.1 Hz, 2H), 1.25 (d, J = 3.2 Hz, 40H), 0.87 (t, J = 6.7 Hz, 6H).;

[0104] 2) Under a nitrogen atmosphere, dissolve compound 1 (5.45 g, 10 mmol), 2,5-bis(tributylstannyl)thiophene (2.22 g, 3.33 mmol), and tetrakis(triphenylphosphine)palladium (0.69 g, 0.6 mmol) in 60 mL of anhydrous N,N-dimethylformamide, react at 120 °C for 8 h. Then add saturated brine, extract with ethyl acetate, wash the organic phase with deionized water multiple times, collect and combine the organic phase and dry it with anhydrous sodium sulfate, remove the solvent by rotary evaporation, and perform column chromatography on the crude product using a mixed solvent of petroleum ether and ethyl acetate (volume ratio of the two is 5:1) as the eluent to obtain a bright yellow oily liquid 2 (2.26 g, yield 66.3%). 1 1H NMR (400 MHz, CDCl3), δ (ppm): 8.74 (s, 1H), 7.46 (s, 1H), 4.25 (d, J = 6.1 Hz, 2H), 1.78 (s, 2H), 1.31 - 1.19 (m, 48H), 0.87 (t, J = 6.7 Hz, 6H);

[0105] 3) Under a nitrogen atmosphere, dissolve compound 2 (1.21 g, 1.2 mmol) and 1,2-dibromotetrachloroethane (1.17 g, 3.6 mmol) in 30 mL of anhydrous tetrahydrofuran, and dropwise add lithium bis(trimethylsilyl)amide solution (3.6 mL, 3.6 mmol) under ice bath conditions, and continue to react at ice bath for 1.5 h. Then add deionized water to quench the reaction, extract with ethyl acetate, dry the organic phase with anhydrous sodium sulfate, remove the solvent by rotary evaporation, and perform column chromatography on the crude product using a mixed solvent of petroleum ether and ethyl acetate (volume ratio of the two is 8:1) as the eluent to obtain an orange-yellow transparent oily liquid compound 3 (0.93 g, yield 67.2%).1 1H NMR (400 MHz, CDCl3), δ (ppm): 7.36 (s, 1H), 4.21 (d, J = 6.1 Hz, 2H), 1.73 (s, 1H), 1.31 - 1.13 (m, 40H), 0.86 (t, J = 6.8 Hz, 6H).

[0106] 4) Under nitrogen protection, compound 3 (58.32 mg, 0.05 mmol) and (3,3'-difluoro-[2,2'-bithiophene]-5,5'-diyl)bis(trimethylstannane) (26.50 mg, 0.05 mmol) were successively added, followed by catalyst tetrakis(triphenylphosphine)palladium (2.88 mg, 2.5 μmol) and 1 mL of anhydrous toluene. The reaction was carried out at 110 °C for 4 h. After the reaction was completed, the crude product was precipitated with methanol, and then successively extracted with acetone, n-hexane, dichloromethane, and chloroform. The chloroform was collected, added with methanol for precipitation, and filtered to obtain the final target polymer PT5ZE-BT2F (42.37 mg, yield 70%); the molecular weight in the THF phase was measured to be 18.1 kDa.

[0107] Comparative Example 1

[0108] A class of non-fused ring polymers based on bi-thiazole, and its synthetic route is shown in Formula 17:

[0109]

[0110] The specific synthesis steps are as follows:

[0111] 1) Under a nitrogen atmosphere, methyl 2-bromothiazole-4-carboxylate (4.44 g, 20 mmol), p-toluenesulfonic acid (3.44 g, 20 mmol), and 2-decyl-1-tetradecanol (8.86 g, 25 mmol) were dissolved in toluene (100 mL). The mixture was refluxed with stirring and reacted overnight. After the reaction was completed, it was allowed to cool to room temperature. Then, distilled water was added to quench the reaction, and the mixture was extracted with dichloromethane. The organic phase was washed with deionized water multiple times. The combined organic phases were collected and dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The crude product was subjected to column chromatography using a mixed solvent of petroleum ether and ethyl acetate (volume ratio 10:1) as the eluent to obtain a light brown liquid compound 1 (8.06 g, yield 73%). 1 1HNMR (400 MHz, CDCl3), δ (ppm): 8.06 (s, 1H), 4.25 (d, J = 6.0 Hz, 2H), 1.79 (m, 1H), 1.39 - 1.21 (m, 40H), 0.87 (t, J = 6.7 Hz, 6H;

[0112] 2) Under a nitrogen atmosphere, compound 1 (6.54 mg, 12 mmol) and activated copper powder (3.05 g, 48 mmol) were added to a two-necked flask. 50 mL of N,N-dimethylformamide was added and stirred until it became a turbid solution. The reaction was carried out at 150 °C for 2 h. After the reaction was completed, the temperature was restored to room temperature. Then, distilled water was added to quench the reaction, and the mixture was extracted with dichloromethane. The organic phase was washed with deionized water multiple times. The combined organic phases were collected and dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The crude product was subjected to column chromatography using a mixed solvent of petroleum ether and dichloromethane (volume ratio 1:3) as the eluent to obtain a beige solid compound 2 (4.04 g, yield 62%). 1 1H NMR (400 MHz, CDCl3), δ (ppm): 8.22 (s, 2H), 4.28 (d, J = 5.8 Hz, 4H), 1.80 (m, 2H), 1.44 - 1.20 (m, 80H), 0.87 (t, J = 6.6 Hz, 12H);

[0113] 3) Under a nitrogen atmosphere, compound 2 (3.81 g, 3.5 mmol) and 1,2-dibromotetrachloroethane (2.85 g, 8.75 mmol) were dissolved in 25 mL of anhydrous THF. Li-HMDS (10.5 mL, 10.5 mmol) was added dropwise at 0 °C. After the addition was complete, the reaction was carried out at 0 °C for 3 h. After the reaction was completed, the mixture was allowed to reach room temperature. Then, distilled water was added to quench the reaction, and the mixture was extracted with dichloromethane. The organic phase was washed with deionized water multiple times. The combined organic phases were collected and dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The crude product was subjected to column chromatography using a mixed solvent of petroleum ether and ethyl acetate (volume ratio 10:1) as the eluent to obtain a white solid compound 3 (2.43 g, yield 64%); 1H NMR (400 MHz, CDCl3), δ (ppm): 4.29 (d, J = 5.6 Hz, 4H), 1.85 - 1.77 (m, 2H), 1.42 - 1.18 (m, 80H), 0.92 - 0.84 (m, 12H);

[0114] 4) Under a nitrogen atmosphere, compound 3 (2.17 g, 2 mmol), tetrakis(triphenylphosphine)palladium (116 mg, 0.1 mmol), and 2-tributylstannylthiophene (1.12 g, 3 mmol) were added to a two-necked flask and dissolved in 10 mL of N,N-dimethylformamide. The reaction was carried out at 120 °C for 3 h. After the reaction was completed, the mixture was allowed to reach room temperature. Then, distilled water was added to quench the reaction, and the mixture was extracted with dichloromethane. The organic phase was washed with deionized water multiple times. The combined organic phases were collected and dried over anhydrous sodium sulfate, and the solvent was removed by rotary evaporation. The crude product was subjected to column chromatography using a mixed solvent of petroleum ether and ethyl acetate (volume ratio 10:1) as the eluent to obtain a yellow solid compound 4 (1.29 g, yield 59%). 11H NMR (400 MHz, CDCl3), δ (ppm): 7.52 (d, J = 3.7 Hz, 2H), 7.49 (d, J = 5.1 Hz, 2H), 7.11 (t, J = 4.5 Hz, 2H), 4.24 (d, J = 6.0 Hz, 2H), 1.72 (m, 1H), 1.43 - 1.18 (m, 40H), 0.95 - 0.85 (m, 12H);

[0115] 5) Dissolve compound 4 (820 mg, 0.75 mmol) in a mixed solution of 20 mL of chloroform and acetic acid (volume ratio 1:1). Under an ice bath and in the dark, add N-bromosuccinimide (320 mg, 1.80 mmol). Then, transfer the mixture to room temperature and react for 2 h, and then heat the reaction at 50 °C overnight. After the reaction is completed, let it stand at room temperature. Then add distilled water to quench the reaction, add saturated sodium bicarbonate aqueous solution to neutralize acetic acid, extract with dichloromethane, and wash the organic phase with deionized water multiple times. Collect and combine the organic phase, dry it with anhydrous sodium sulfate, and remove the solvent by rotary evaporation. Use a mixed solvent of petroleum ether and dichloromethane (volume ratio of the two is 3:2) as the eluent for column chromatography to obtain yellow solid compound 5 (782 mg, yield 77%). 1 1H NMR (400 MHz, CDCl3), δ (ppm): 7.27 (d, J = 3.9 Hz, 2H), 7.06 (d, J = 3.9 Hz, 2H), 4.26 (d, J = 6.0 Hz, 4H), 1.77 - 1.66 (m, 2H), 1.35 - 1.20 (m, 80H), 0.95 - 0.89 (m, 12H).

[0116] The synthetic route of the bithiazole all non-fused ring polymer material is shown in Formula 18;

[0117]

[0118] Under nitrogen protection, successively add compound 5 (63.74 mg, 0.05 mmol), (3,3'-difluoro-[2,2'-bithiophene]-5,5'-diyl)bis(trimethyltin) (26.31 mg, 0.05 mmol), catalyst tetrakis(triphenylphosphine)palladium (2.88 mg, 2.5 μmol), and 1 mL of anhydrous toluene, and react at 120 °C for 3.5 h. After the reaction is completed, precipitate the crude product with methanol, and then successively extract it with acetone, n-hexane, dichloromethane, and chloroform. After the chloroform is basically colorless, put the filter paper package into chlorobenzene and heat it to reflux for 3 h. After cooling, take out the filter paper package, recover the chlorobenzene solution, and remove chlorobenzene by rotary evaporation. The obtained dark red metallic shiny film-like solid is the product PZ2E-BT2F (38 mg, yield 52%). The molecular weight of the CF phase is measured to be 17.5 kDa.

[0119] Figure 8 The UV-visible absorption spectra of the polymer PZ2E-BT2F obtained in Comparative Example 1 are shown in chloroform solution (room temperature) and in thin film state, respectively. Among them, the solution concentration is 1×10 -5 g / mL. As Figure 8 shown, in the solution state, PZ2E-BT2F shows two characteristic absorption peaks: the absorption peak at short wavelength is 550 nm, attributed to π-π electronic transition; the absorption peak at 601 nm is an aggregation shoulder peak, and its extinction coefficient is slightly lower than that of the absorption peak at short wavelength. In the thin film, its main absorption peak is at 552 nm and the shoulder peak is at 604 nm. The solution absorption spectra of the polymer are all blue-shifted compared to the thin film, which proves that aggregation behavior occurs during the film formation process and the π-π stacking is strengthened.

[0120] The narrow-bandgap acceptor material L8-BO (structural formula shown in Formula 13) was selected and blended with the fully non-fused-ring polymer donor material PZ2E-BT2F described in this comparative example. The prepared thin film can cover a wide absorption range from 400 nm to 900 nm (see Figure 9 ), ensuring full utilization of light by the thin film. The prepared binary organic solar cell can obtain a relatively high short-circuit current.

[0121] The redox process of PZ2E-BT2F was tested by electrochemical cyclic voltammetry. Using ferrocene as the reference (vacuum level is -4.8 eV), the initial redox potential corresponding to this polymer molecule was obtained. The highest occupied molecular orbital energy level (HOMO) and the lowest unoccupied molecular orbital energy level (LUMO) of the material can be obtained according to the formula: E HOMO = -(E ox onset - E Fc / Fc+ + 4.8) eV and E LUMO = -(E red onset - E Fc / Fc+ + 4.8) eV. It can be seen from Figure 8 that: according to the above formula, the HOMO energy level of the polymer PZ2E-BT2F can be calculated to be -5.49 eV. Since no obvious reduction potential was observed, the LUMO energy level was obtained based on the HOMO energy level of the material and the optical bandgap difference, which is -3.62 eV (see Figure 3 ).

[0122] The narrow-band series acceptor material L8-BO (structural formula shown in Formula 13) was selected and blended with the dithiazole fully non-fused-ring polymer donor material obtained in this comparative example to prepare a thin film. A binary organic solar cell was prepared, and the forward device structure: ITO / PEDOT:PSS / PZ2E-BT2F:L8-BO / PDIN / Ag was used to test the photovoltaic performance of the cell.Figure 10 As shown, after optimizing the device fabrication process, the PCE of the battery device is only 6.46%, where V oc is 0.926 V, and J sc is 15.38 mA / cm 2 , and the FF is 45.38%.

[0123] To correspond to the influence of the active layer morphology on the device performance, the exposed test materials of the active layer of the device based on PZ2E - BT2F:L8 - BO were tested by Atomic Force Microscope (AFM). The results are as Figure 11 shown. The roughness of the PZ2E - BT2F:L8 - BO device is moderate, and the R q value is 1.456 nm. Combining its phase diagram, it can be noted that there is a moderate phase separation.

[0124] Based on Comparative Example 1, in Example 1 of the present invention, a thiophene π - bridge was introduced between the diester - based thiazoles of unit A to synthesize PTZ2E - BT2F. Compared with the binary device of PZ2E - BT2F:L8 - BO, the PCE value was increased from 6.46% to 8.81%. Although V oc slightly decreased, the J sc and FF values of the device based on PTZ2E - BT2F:L8 - BO were better improved, resulting in an increase in the PCE value. The increased J sc is mainly due to the enhanced ability to capture photons in the range of 400 - 600 nm. The molecular backbone structure of PTZ2E - BT2F obtained by introducing the thiophene π - bridge achieved a more compact molecular packing, ensuring stronger molecular crystallization ability. Due to the enhanced planarity of the molecular backbone, the aggregation of PTZ2E - BT2F is stronger, and the stacking absorption shoulder peak in the absorption spectrum is more significant. At the same time, a good bicontinuous network distribution is also shown in the blend film. Therefore, the device based on PTZ2E - BT2F:L8 - BO obtained improved J sc and FF. According to the AFM test results, a more favorable interpenetrating structure is shown inside PTZ2E - BT2F:L8 - BO compared to PZ2E - BT2F, and the fiber sizes are more average. Therefore, the phase separation between PTZ2E - BT2F and L8 - BO is more appropriate, improving the morphology of the active layer, which is beneficial to obtaining a higher exciton separation efficiency to promote the improvement of the device FF and J sc .

[0125] The dithiazole-based all non-fused-ring polymer described in the present invention is prepared by copolymerizing an arene-expanded dithiazole as an electron-deficient unit with a halogenated or halogen-free thiophene, selenophene or bithiophene as an electron-donating unit. By means of molecular engineering, an arene is used as the core-expanded dithiazole electron-deficient unit, and the oxygen atom in the alkoxy group can form an S-O non-covalent interaction with the N atom in the thiazole heterocycle to form a conformational lock, thereby inhibiting the rotation of the single bond and making the main chain flatter, improving the charge transport. In addition, the introduction of the dithiazole unit can adjust the energy level structure of the material and inhibit energy loss. The synergistic effect of arene expansion and halogenation optimization can significantly adjust the performance parameters of the material, and the constructed all non-fused-ring structure also has a simple structure and low preparation cost. When this type of polymer is used as an active layer material or a third component in organic optoelectronic devices, low-cost and high-efficiency battery devices can be obtained.

[0126] The above embodiments are only used to illustrate the technical concept and features of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly, and it cannot be used to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.

Claims

1. An aromatic ring-expanded dithiazole all non-fused-ring polymer, characterized in that, It contains an electron-deficient unit with a symmetric structure, and the electron-deficient unit has a dithiazole structure extended by an aromatic ring core Ar; the structural formula of the polymer is one or more of those shown in Formula 1: Wherein, R is one of an alkyl group having C1 to C 30 , an alkoxy group having C1 to C 30 , an ester group having C1 to C 30 , or a mercapto group; D is selected from one of thiophene, selenophene, bithiophene, or a corresponding halogen-substituted group; the electron-deficient unit core Ar is selected from one of thiophene, selenophene, benzene ring, pyrazine; and n ranges from 10 to 100.

2. The dithiazole all non-fused ring polymer according to claim 1, wherein The structural formula of the aromatic ring core Ar is specifically one of those shown in Formula 2:

3. The dithiazole all non-fused ring polymer according to claim 1, characterized in that, The D unit is specifically selected from the following structures:

4. The dithiazole all non-fused ring polymer according to claim 1, characterized in that, The halogen group used for the halogen substitution is one or more of F and Cl.

5. The dithiazole all non-fused ring polymer according to claim 1, characterized in that, The molecular weight range of the polymer is 20,000 to 600,000.

6. The preparation method of the aromatic ring-expanded dithiazole all non-fused ring polymer according to claim 1, characterized in that, It includes the following steps: Under catalytic conditions, a halogenated electron-deficient unit monomer and a dimethyltin electron-donating unit monomer are subjected to Stille polymerization, and then extraction is carried out to obtain the all non-fused-ring polymer.

7. The preparation method according to claim 6, characterized in that, The structural formula of the halogenated electron-deficient unit monomer is one of those shown in Formula 4; In the formula, R is selected from one of an alkyl group, an alkoxy group, an ester group or a mercapto group of C1 to C 30 One of the alkyl, alkoxy, ester or mercapto groups.

8. The preparation method according to claim 6, characterized in that, The structural formula of the dimethyltin D unit monomer is shown in Formula 5; In the formula, X is H or a halogen atom; D is selected from thiophene, selenophene or bithiophene.

9. The preparation method according to claim 6, characterized in that, The temperature used for the Stille polymerization is 100 - 140 °C, and the time is 1 - 12 h.

10. Use of the aryl-extended dithiazole all non-fused ring polymer according to any one of claims 1 to 5 or the aryl-extended dithiazole all non-fused ring polymer obtained by the preparation method according to any one of claims 6 to 9 as an active layer material in an optoelectronic device, characterized in that, Blend the aryl-extended dithiazole all non-fused-ring polymer with a medium bandgap acceptor material and a narrow bandgap acceptor material.

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