Water-alcohol-soluble conjugated polymer based on naphtho-diimide and phenyl unit, preparation method and application of water-alcohol-soluble conjugated polymer

Abstract

The water-alcohol-soluble conjugated polymer based on the naphtho-diimide and the phenyl unit, the preparation method and the application of the water-alcohol-soluble conjugated polymer under continuous irradiation of ultraviolet light have good ultraviolet light stability, and in addition, the water-alcohol-soluble conjugated polymer has good device efficiency in photoelectric devices. According to the invention, a conjugated group with good ultraviolet light stability is introduced into a polymer main chain to develop a water-alcohol-soluble polymer electron transport material, so that the light stability is improved; different from a traditional synthesis method of a polymer electron transport material, the method provided by the invention adopts a direct hydrocarbon activation polymerization method, so that the synthesis process is simplified, and the material synthesis cost is reduced.

Description

Technical Field

[0001] The invention belongs to the field of organic polymer materials, and in particular relates to a water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units, a preparation method and application thereof. Background Art

[0002] Organic semiconductor materials are flexible, lightweight, and solution processable, and are widely used in organic electronic devices, such as organic solar cells, organic photodetectors, organic light-emitting diodes, and organic thin-film transistors. Organic semiconductor materials are easy to control in terms of chemical structure, and can be designed and synthesized through different chemical reactions to obtain materials with different properties to meet the application requirements in different organic electronic devices.

[0003] In recent years, through the design of materials and the optimization of device structure, the photoelectric conversion efficiency of organic solar cells has exceeded 20%. High-efficiency organic solar cells have a multi-layer device structure, generally with an anode / hole transport layer / active layer / electron transport layer / cathode structure. The active layer material is responsible for absorbing photons and generating excitons after being excited. The excitons split at the donor-acceptor interface to generate electrons and holes, which pass through the electron transport layer and the hole transport layer respectively and are then collected by the electrode. Among them, the electron transport layer plays the role of transmitting electrons and blocking holes, and can adjust the work function of the electrode to achieve ohmic contact and improve the charge collection efficiency at the electrode.

[0004] According to the literature (Novel Electroluminescent Conjugated Polyelectrolytes Based on Polyfluorene.Chem.Mater.,2004,16,708-716.), the water-alcohol soluble conjugated polymer PFN-Br based on the polyfluorene main chain and polar side chain can be dissolved in a methanol solution, so it can be used in the electron transport layer to improve the luminous efficiency of the organic light-emitting diode device through the orthogonal solvent processing method. In addition, the literature (Simultaneous Enhancement of Open-Circuit Voltage, Short-Circuit Current Density, and Fill Factor in Polymer Solar Cells.Adv.Mater.2011,23,4636-4643) also uses PFN as the electron transport layer of organic solar cells to improve the photoelectric conversion efficiency of the battery device. However, this type of material can only work normally under relatively thick film thickness. After that, the literature (n-Type Water / Alcohol-Soluble Naphthalene Diimide-Based Conjugated Polymers for High-Performance Polymer Solar Cells. J. Am. Chem. Soc. 2016, 138, 6, 2004–2013) reported that the electron-deficient unit naphthodiimide unit was embedded in the polyfluorene main chain to obtain PNDITF3N, and this type of material can still maintain a high device efficiency when the film thickness increases. However, the fluorene unit is unstable under ultraviolet light. For example, the literature (On the Degradation Process Involving Polyfluorenes and the Factors Governing Their Spectral Stability. Macromolecules 2011, 44, 7977–7986) reported that after irradiation with ultraviolet light, the organic light-emitting diode device based on polyfluorene will increase from emitting blue light to emitting green light.

[0005] The Chinese invention patent with publication number CN104725613A discloses an n-type water-alcohol soluble conjugated polymer material containing a naphthodiimide ring, a preparation method and an application thereof. The polymer main chain reported in the patent contains a fluorene unit, which is unstable under ultraviolet light and has a destructive effect on the stability of the polymer material.

[0006] Therefore, in order to further improve the stability of materials and devices, further structural optimization of electron transport materials is needed. Summary of the invention

[0007] Therefore, the object of the present invention is to provide a water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units, which has good ultraviolet light stability under continuous irradiation of ultraviolet light and has good device efficiency in optoelectronic devices.

[0008] The present invention discloses a water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units. The water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units comprises polymer 1, and / or polymer 2:

[0009] in,

[0010] The polymer 1 has the following structure (I):

[0011]

[0012] The polymer 2 has the following structure (II):

[0013]

[0014] Wherein, n is a natural number from 1 to 10000, and n is not 1;

[0015] In the polymer 1, the R1 is selected from one or more of aromatic derivatives and alkyl derivatives containing ionized water-alcohol-soluble polar groups;

[0016] X - is the counter ion;

[0017] In the polymer 2, the R1′ is selected from one or more of aryl derivatives and alkyl derivatives containing non-ionized water-alcohol-soluble polar groups;

[0018] Wherein, all carbon atoms on the alkyl derivative are unsubstituted, or one or more carbon atoms are substituted by one or more of oxygen atoms, amino groups, sulfone groups, carbonyl groups, aryl groups, alkenyl groups, alkynyl groups, ester groups, cyano groups, and nitro groups;

[0019] or

[0020] All hydrogen atoms on the alkyl derivative are unsubstituted, or one or more hydrogen atoms are substituted by one or more of halogen, hydroxyl, amino, carboxyl, cyano, nitro, aryl, alkene, and alkyne groups;

[0021] The aryl derivative is selected from a group containing one or more benzene ring structures, wherein the hydrogen atoms on all benzene rings are not substituted,

[0022] or

[0023] One or more hydrogen atoms at any position on one or more benzene rings are replaced by one or more of halogen, hydroxy, amino, carboxyl, cyano, nitro, aryl, olefin, alkyne, carboxyl, ester, cyano or nitro;

[0024] The R2 is selected from one or more of an alkyl group or an aryl group.

[0025] Furthermore, the polymer 1 has the following structure:

[0026]

[0027] The polymer 2 has the following structure:

[0028]

[0029] The n1 is a natural number between 2 and 30;

[0030] C is a water-alcohol-soluble polar group.

[0031] Furthermore, in the polymer 1, the C is selected from one or more of a quaternary ammonium salt group, a phosphate group, a sulfonate group, an acetate group, a quaternary phosphonium salt group and a phosphate ester group.

[0032] Furthermore, in the polymer 2, the C is selected from a tertiary amine group.

[0033] Furthermore, the ion part X in the polymer 1 - The structure is selected from one of the following structures:

[0034] Contains one or more of boron organic anions and halogen anions.

[0035] Preferably, the boron-containing organic anion is selected from the following structures:

[0036] Further, the R2 is selected from a "herringbone" branched alkyl chain structure;

[0037] The herringbone branched alkyl chain structure is selected from one or more of a C2-C6 alkyl chain structure, a C4-C8 alkyl chain structure, and a C3-C10 alkyl chain structure.

[0038] The present invention also provides a method for preparing a water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units, comprising the following steps:

[0039] S1. Under the protection of an inert gas, compound 2 and a halogenated naphthodiimide unit are subjected to a coupling reaction under the action of a palladium catalyst to obtain a water-alcohol soluble conjugated polymer;

[0040] Wherein, the compound 2 is selected from the following structures:

[0041] The R3 does not exist, or is selected from one or more of an aryl group or an alkyl group.

[0042] Furthermore, the method further comprises the following steps:

[0043] S2. Adding the water-alcohol soluble conjugated polymer into a solvent, and then adding a halogenated compound to perform a salification treatment to obtain a water-alcohol soluble conjugated polymer containing a counter ion.

[0044] Furthermore, in step S1, the coupling reaction temperature is 85-90°C.

[0045] The present invention also provides the use of the water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units in organic solar cells.

[0046] The organic solar cell comprises the following structures from bottom to top: a substrate, a hole transport layer, an active layer, an electron transport layer, and an anode;

[0047] The material of the electron transport layer includes a water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units.

[0048] Compared with the prior art, the main advantages of the present invention are as follows:

[0049] The present invention develops a water-alcohol soluble polymer electron transport material by introducing a conjugated group with good ultraviolet light stability into the polymer main chain, thereby improving the light stability. In addition, the present invention is different from the traditional synthesis method of polymer electron transport materials. It adopts a direct carbon-hydrogen activated polymerization method, simplifies the synthesis process, and reduces the material synthesis cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 The current density and voltage spectrum of the organic solar cell device with polymer P1, polymer P2, polymer P3, polymer P4 and PFN-Br, PNDITF3N as the electron transport layer under illumination;

[0051] Figure 2 is the full spectrum of X-ray photoelectron spectrum of polymer P1;

[0052] Figure 3 This is the full spectrum of X-ray photoelectron spectrum of polymer P2;

[0053] Figure 4 This is the full spectrum of X-ray photoelectron spectrum of polymer P3;

[0054] Figure 5 This is the full spectrum of X-ray photoelectron spectrum of polymer P4;

[0055] Figure 6 The UV-visible absorption spectra of polymer P1, polymer P2, polymer P3, and polymer P4 in methanol solution and film;

[0056] Figure 7 This is the UV-visible absorption spectrum of the reported electron transport material PNDITF3N film under continuous UV light irradiation;

[0057] Figure 8 This is the UV-visible absorption spectrum of the polymer P1 film under continuous UV light irradiation;

[0058] Fig. 9 This is the UV-visible absorption spectrum of the polymer P2 film under continuous UV light irradiation;

[0059] Fig.10 The current density and voltage spectrum of the organic solar cell device with polymer P2, polymer P3, polymer P4 and PFN-Br as the electron transport layer in the dark state;

[0060] Fig.11 This is a diagram showing the stability of organic solar cell devices under ultraviolet light for polymer P1 and comparison polymers PFN-Br and PNDITF3N. DETAILED DESCRIPTION

[0061] In order to more clearly illustrate the technical solution of the present invention, the following examples are listed. Unless otherwise stated, the raw materials, reactions and post-treatment methods shown in the examples are common raw materials on the market and technical methods well known to those skilled in the art.

[0062] In the embodiments of the present invention, unless otherwise mentioned, the steps for preparing the organic solar cell all adopt conventional means well known to those skilled in the art.

[0063] Example 1

[0064] Preparation of polymerized monomers containing tertiary amine functional groups in the side chains of phenyl units, the reaction formula is as follows:

[0065]

[0066] S1-1, Synthesis of Compound 1-2:

[0067] Compound 1-1 (6.5 g) was added to a 250 ml two-necked reaction bottle, 13.4 g of potassium carbonate was weighed and added, the reaction bottle was evacuated with a pump and then nitrogen was blown in for 5 min, 100 ml of acetone was added under nitrogen, and then 15 ml of 1,3-dibromopropane was added with a syringe, and the reaction was heated to 70 ° C for 12 h. After cooling to room temperature, the reaction mixture was filtered, the filtrate was collected, and the solution was concentrated using a rotary evaporator to obtain a crude product, which was further purified by silica gel column chromatography to obtain 8.8 g of a white solid (compound 1-2) with a yield of 71%.

[0068] The H NMR spectrum of compound 1-2 is shown below:

[0069] 1 H NMR (400MHz, Chloroform-d) δ7.13 (s, 1H), 4.11 (t, J = 5.7Hz, 2H), 3.66 (t, J = 6.4Hz, 2H), 2.34 (p, J = 6.0Hz, 2H).

[0070] S1-2. Synthesis of Compound 1:

[0071] Compound 1-2 (2.1 g) was added to a 100 ml two-necked reaction bottle, 0.5 g of tetrakistriphenylphosphine palladium was weighed and added, the reaction bottle was evacuated with a pump and then nitrogen was blown for 5 min, 40 ml of toluene was added under nitrogen, and then 5 ml of 2-tributylstannylthiophene was added with a syringe, heated to 90 ° C and reacted for 24 h. After the detection reaction was completed, the reaction mixture was cooled to room temperature, and the solution was concentrated using a rotary evaporator to obtain a crude product, which was then further purified by silica gel column chromatography to obtain 0.67 g of a light green solid (compound 1), with a yield of 33%.

[0072] The H NMR spectrum of compound 1 is shown below:

[0073] 1 H NMR(400MHz,Chloroform-d)δ7.49(d,J=3.7Hz,1H),7.36(d,J=5.1Hz,1H),7.28(s,1H),7.1 1(dd,J=5.2,3.6Hz,1H),4.24(t,J=5.7Hz,2H),3.70(t,J=6.4Hz,2H),2.42(p,J=6.1Hz,2H).

[0074] S1-3. Synthesis of Compound 2:

[0075] Compound 1 (0.8 g) was dissolved in 8 ml of tetrahydrofuran, evacuated with a pump, and then filled with nitrogen, repeated three times, and then 5 ml of diethylamine was added with a syringe, heated to 65 ° C and reacted for 12 hours. After the reaction was detected, the reaction mixture was cooled to room temperature. The solution was concentrated using a rotary evaporator to obtain a crude product, which was further purified by silica gel column chromatography to obtain 0.6 g of a white solid (compound 2) with a yield of 77%.

[0076] The H NMR spectrum of compound 2 is shown below:

[0077] 1 H NMR(400MHz,Chloroform-d)δ7.52(d,J=3.7Hz,1H),7.33(d,J=5.1Hz,1H),7.09(t,J=4.4Hz,1H),4.14(t ,J=6.1Hz,2H),2.71(t,J=7.5Hz,2H),2.57(q,J=7.1Hz,4H),2.06(p,J=6.3Hz,2H),1.04(t,J=7.1Hz,6H).

[0078] Example 2

[0079] Preparation of water-alcohol soluble conjugated polymers based on naphthodiimide and phenyl units, the reaction formula is as follows:

[0080]

[0081] S1-4. Synthesis of polymer P1:

[0082] 2,6-Dibromo-N,N'-diisooctyl-1,4,5,8-naphthodiimide (Compound 3, 272.7 mg), Compound 2 (210.6 mg), potassium carbonate (145.3 mg), pivalic acid (43.0 mg) and catalyst (tris(dibenzylidene indene acetone) dipalladium, 7.7 mg) were mixed in a 48 ml sealed tube, evacuated with a pump, and then filled with nitrogen, and repeated three times. Chlorobenzene (8 ml) was added under argon, and the reaction mixture was stirred at 90°C for 72 h. After cooling to room temperature, the reaction mixture was poured into methanol (200 ml) to form a dark green precipitate. The precipitate was filtered and the crude polymer product was extracted with methanol, acetone, n-hexane and chloroform in sequence using a Soxhlet extraction apparatus. The chloroform-extracted solution was concentrated and precipitated into methanol. The precipitate was collected and dried in a vacuum overnight to obtain polymer P1 (401.8 mg) with a yield of 96.6%.

[0083] Other embodiments

[0084] The syntheses of P2-P4 are as follows.

[0085] Synthesis of polymer P2:

[0086] The polymer P1 (294.8 mg) was dissolved in 5 ml of chloroform, and then 5 ml of ethyl bromide was added. The mixture was stirred at 50° C. for 3 days. Once a precipitate appeared, an appropriate amount of methanol was added to dissolve it, and then the solvent was removed by distillation under reduced pressure. The crude product was dissolved in methanol (10 ml), and the solution was filtered through a 0.45 μm PTFE filter head. After concentration, it was precipitated in ethyl acetate to precipitate insoluble solids. The solids were collected and dried in vacuum overnight to obtain polymer P2 (350.4 mg) with a yield of 97.5%. The product was characterized by XPS to verify the successful introduction of Br ions (such as Figure 3 shown).

[0087] Synthesis of polymer P3:

[0088] The polymer P2 (42 mg) was dissolved in 3 ml of methanol, and then potassium fluoride (200 mg) was dissolved in a mixed solvent of 1.5 ml of methanol and 0.5 ml of deionized water, and the mixture was stirred at room temperature for 72 h. The solvent was then removed by distillation under reduced pressure from the reaction solution. The crude product was washed with excess deionized water and then dried in a vacuum oven to obtain the target polymer P3 (34.8 mg) with a yield of 96.8%. The product was characterized by XPS to verify that the ions had been completely exchanged (e.g. Figure 4 shown).

[0089] Synthesis of polymer P4:

[0090] The polymer P2 (35 mg) was dissolved in 3 ml of methanol, and then sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (1.5 g) was dissolved in a mixed solvent of 1 ml of methanol and 0.5 ml of deionized water, and stirred at room temperature for 72 h. The reaction solution was then distilled under reduced pressure to remove the solvent, the crude product was washed with excess deionized water, and then dried in a vacuum oven to obtain the target polymer P4 (741.1 mg) with a yield of 92.1%. The product was characterized by XPS to verify that the ions had been completely exchanged (such as Figure 5 shown).

[0091] Comparative Example 1

[0092] A polymer (PNDITF3N), the preparation method of which is shown in the Chinese patent publication number CN104725613A, and its structure is shown below:

[0093]

[0094] The conjugated main chain of the polymer is composed of an electron-deficient unit naphthiodiimide, a thiophene bridging unit and an electron-donating unit fluorene. Due to the introduction of the electron-deficient unit naphthiodiimide, the polymer has achieved good device efficiency in organic solar cell devices. However, during the synthesis process, boric acid ester needs to be introduced into the fluorene unit for subsequent polymerization reaction. The synthesis and purification of boric acid ester are relatively cumbersome, and the overall synthesis of the polymer requires more reaction steps, which is not conducive to large-scale preparation.

[0095] And, as in Test Example 4 and Figure 7 As shown, polymers containing fluorene units are unstable to UV light, which affects the long-term stability of the material.

[0096] As shown in Test Example 6 and Fig.11 As shown, when it is applied to the cathode interface layer of an organic solar cell device, the photostability of the device will be significantly attenuated.

[0097] Test Example 1

[0098] Polymer P2, polymer P3 and polymer P4 are used as donor materials in the electron transport layer of an organic solar cell, and this is used as an example to illustrate the application of the electron transport type water-alcohol soluble polymer material proposed in the present invention in an organic photoelectric device.

[0099] For comparison, the disclosed high-performance electron transport materials PFN-Br and PNDITF3N (Comparative Example 1) were selected to further demonstrate the improvement in performance of the material proposed in the present invention.

[0100] (1) Preparation of organic solar cell devices

[0101] The structure of the organic solar cell device is from bottom to top: ITO substrate (700nm) / PEDOT:PSS hole transport layer (40nm) / PM6:BTP-eC9 active layer (100nm) / electron transport layer (10nm) / Ag anode (100nm);

[0102] PFN-Br and PNDITF3N were purchased from Dongguan Fuan Optoelectronics Co., Ltd. The relevant chemical structures are as follows:

[0103]

[0104] The chemical structure of the active layer material used is as follows:

[0105]

[0106] The detailed preparation process is as follows:

[0107] The glass substrate coated with indium tin oxide (ITO) was cleaned with deionized water, acetone and isopropanol at room temperature for 20 min respectively, and then dried in an oven at 60 °C for 12 h. Then, a 40 nm thick poly(3,4-ethylenedioxythiophene):polystyrenesulfonic acid (PEDOT:PSS, model: CLEVIOS PVPAl 4083) was spin-coated on the cleaned ITO glass substrate and heated on a heating stage at 140 °C for 15 min in air.

[0108] The active layer donor material conjugated polymer PM6 and the acceptor material BTP-eC9 were weighed in a clean bottle (mass ratio of 1:1.2), transferred to a nitrogen-protected film-forming glove box (purchased from VAC), dissolved in a solvent containing 1 wt% of 1,8-diiodooctane to obtain a PM6:BTP-eC9 solution with a concentration of 10 mg / ml, and then spin-coated on the PEDOT:PSS film with a thickness of 100 nm as an active layer using a spin coater and a surface profiler;

[0109] Different electron transport layer materials (PFN-Br, PNDITF3N, polymer P1, polymer P2, polymer P3, polymer P4) were respectively prepared into solutions with a mass concentration of 1 mg / ml using polar solvent methanol, and spin-coated on the active layer with a thickness of 10 nm to serve as the electron transport layer of the solar cell device;

[0110] The film was transferred to a vacuum deposition chamber connected to the glove box and then deposited through a mask at about 10 -7 Ag (100 nm) anode was evaporated under the condition of Pa;

[0111] Among them, all preparation processes of organic solar cell devices are carried out in a glove box with oxygen and water content less than 1 ppm.

[0112] The relationship between the current density and voltage of an organic solar cell device under illumination is as follows: Figure 1 The specific device efficiency is shown in Table 1.

[0113] Table 1 Performance of organic solar cells based on different electron transport materials

[0114] Electron transport layer <![CDATA[Open-circuit voltage V OC [V]]]> <![CDATA[Short-circuit current J SC [mA / cm 2 > Fill factor [%] Conversion efficiency [%] Polymer P1 0.820±0.00 27.99±0.38 76.45±0.33 17.59±0.22 Polymer P2 0.819±0.00 27.97±0.41 76.32±0.93 17.49±0.12 Polymer P3 0.824±0.000 28.03±0.04 76.39±0.66 17.64±0.17 Polymer P4 0.715±0.005 27.36±0.56 60.62±1.05 11.86±0.37 PFN-Br 0.825±0.002 26.87±0.50 75.75±1.35 16.80±0.57 PNDITF3N 0.821±0.001 27.20±0.42 76.02±0.82 17.22±0.13

[0115] From Table 1 and Figure 1 It can be seen that polymers with different counter ions produce different device effects. The electron transport layer based on polymers P1, P2 and P3 has significantly improved device efficiency compared with PFN-Br, while the efficiency of the electron transport layer based on polymer P4 is significantly reduced. The results show that the introduction of phenyl units in the main chain does not reduce the device efficiency, but the change of counter ions in the side chain will significantly affect the device efficiency.

[0116] Test Example 2

[0117] X-ray photoelectron spectroscopy tests were performed on polymers P1, P2, P3 and P4. The test results are as follows: Figure 2-5 shown.

[0118] The results show that compared with polymer P1 with a neutral tertiary amine functional group on the side chain, polymer P2 with a quaternary ammonium salt functional group on the side chain has a Br ion peak introduced, polymer P3 has an F ion peak introduced, and polymer P4 has both B ion and F ion peaks introduced, which proves the synthesis of related materials.

[0119] Test Example 3

[0120] The UV-visible absorption spectrum of polymer P1, polymer P2, polymer P3 and polymer P4 was tested.

[0121] Test method: Dissolve polymer P1 in 10 mg / ml methanol solution (+1% volume acetic acid), polymer P2, polymer P3 and polymer P4 in 10 mg / ml methanol solution, then add 20 μL of the above polymer solution to a cuvette containing methanol solvent to perform solution absorption test. Spin coat the above solutions onto 1.5×1.5 cm 2 The film absorption test was carried out on the quartz plate. The relevant absorption data is shown in the attached Figure 6 shown.

[0122] from Figure 6 It can be seen that different groups at the end of the side chain will significantly affect the absorption spectrum of the material. Compared with the polymer P2 based on Br ions, the polymer P3 based on F ions has a weaker aggregation peak. The polymer P4 with B ions has a larger volume, which weakens the stacking of the polymer main chain, causing a significant blue shift in the absorption spectrum.

[0123] Test Example 4

[0124] Polymer P1, Polymer P2 and PNDITF3N were tested for UV stability.

[0125] Test method: Spin-coat 10mg / ml methanol solution of polymer P1, polymer P2 and PNDITF3N onto a quartz wafer, and then irradiate under a 365nm UV lamp with a power of 45W. After a certain irradiation time, perform a thin film spectral absorption test. Figure 7-9 shown.

[0126] The results show that the UV stability of the material can be effectively improved by replacing the fluorene unit in PNDITF3N with a phenyl unit through the main chain adjustment strategy. And when the side chain terminal group is changed, both the tertiary amine of polymer P1 and the quaternary ammonium salt of polymer P2 can still maintain good UV stability.

[0127] Test Example 5

[0128] The organic solar cells prepared in Test Example 1 with polymers P2, P3, P4 and PFN-Br as electron transport layers were placed in a dark state to test the variation trend of the current density of the device with the voltage. The results are shown in the attached figure. Fig.10 shown.

[0129] It can be seen that the devices based on PFN-Br and polymers P2 and P3 have significantly reduced dark current, and the dark current of the device based on polymer P4 is relatively the highest. The lower the dark current, the more conducive it is to the improvement of the overall current density of the device under illumination, which also corresponds to the photoelectric conversion efficiency of the device.

[0130] Test Example 6

[0131] The stability test of photovoltaic performance was conducted on the organic solar cell with polymer P1 prepared in Test Example 1 and PNDITF3N and PFN-Br as electron transport layers. The specific operation was to place the prepared organic solar cell device under 6W 365nm ultraviolet light in a glove box, and then conduct the photoelectric conversion efficiency test after a certain time interval. The results are shown in the attached figure. Fig.11 shown.

[0132] The results show that by replacing the fluorene unit in PNDITF3N with a phenyl unit through the main chain adjustment strategy, the ultraviolet light stability of the organic solar cell device can be improved, and the stability is also significantly improved compared to PFN-Br with fluorene as the main chain.

[0133] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0134] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units, characterized in that: The water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units includes polymer 1, and / or polymer 2: in, The polymer 1 has the following structure (I): The polymer 2 has the following structure (II): Wherein, n is a natural number from 1 to 10000, and n is not 1; In the polymer 1, the R1 is selected from one or more of aromatic derivatives and alkyl derivatives containing ionized water-alcohol-soluble polar groups; X - is the counter ion; In the polymer 2, the R1′ is selected from one or more of aryl derivatives and alkyl derivatives containing non-ionized water-alcohol-soluble polar groups; Wherein, all carbon atoms on the alkyl derivative are unsubstituted, or one or more carbon atoms are substituted by one or more of oxygen atoms, amino groups, sulfone groups, carbonyl groups, aryl groups, alkenyl groups, alkynyl groups, ester groups, cyano groups, and nitro groups; or All hydrogen atoms on the alkyl derivative are unsubstituted, or one or more hydrogen atoms are substituted by one or more of halogen, hydroxyl, amino, carboxyl, cyano, nitro, aryl, alkene, and alkyne groups; The aryl derivative is selected from a group containing one or more benzene ring structures, wherein the hydrogen atoms on all benzene rings are not substituted, or One or more hydrogen atoms at any position on one or more benzene rings are replaced by one or more of halogen, hydroxy, amino, carboxyl, cyano, nitro, aryl, olefin, alkyne, carboxyl, ester, cyano or nitro; The R2 is selected from one or more of an alkyl group or an aryl group.

2. The water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units according to claim 1, characterized in that: The polymer 1 has the following structure: The polymer 2 has the following structure: The n1 is a natural number between 2 and 30; C is a water-alcohol-soluble polar group.

3. The water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units according to claim 2, characterized in that: In the polymer 1, the C is selected from one or more of a quaternary ammonium salt group, a phosphate group, a sulfonate group, an acetate group, a quaternary phosphonium salt group and a phosphate ester group.

4. The water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units according to claim 2, characterized in that: In the polymer 2, the C is selected from a tertiary amine group.

5. The water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units according to claim 2, characterized in that: The counter ion portion X in the polymer 1 - The structure is selected from one of the following structures: Contains one or more of boron organic anions and halogen anions.

6. The water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units according to claim 1, characterized in that: The R2 is selected from a "herringbone" branched alkyl chain structure; The "herringbone" branched alkyl chain structure is selected from one or more of a C2-C6 alkyl chain structure, a C4-C8 alkyl chain structure, and a C3-C10 alkyl chain structure.

7. The method for preparing a water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units according to any one of claims 1 to 6, characterized in that: The steps include: S1, under the protection of an inert gas, coupling the compound 2 and the halogenated-naphthodiimide unit under the action of a palladium catalyst to obtain a polymer 2; Wherein, the compound 2 is selected from the following structures: The R3 does not exist, or is selected from one or more of an aryl group or an alkyl group.

8. The method for preparing a water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units according to claim 7, characterized in that: The following steps are also included: S2. Add polymer 2 into a solvent, and then add a halogenated compound to perform a salification treatment to obtain polymer 1.

9. The method for preparing a water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units according to claim 7, characterized in that: In step S1, the coupling reaction temperature is 85-90°C.

10. Use of the water-alcohol soluble conjugated polymer based on naphthodiimide and phenyl units according to any one of claims 1 to 6 in organic solar cells.

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