Preparation method and application of aggregation-induced emission electron acceptor material

Abstract

The invention discloses a preparation method and application of an aggregation-induced emission electron acceptor material. The electron acceptor material has a structure as shown in figure 1, is of a non-condensed ring structure, and keeps the planarity of a conjugated main chain while having good solubility. Such electron acceptor materials have aggregation-induced emission properties, resulting in higher photoluminescence quantum yield (20%). The polymer is applied to the field of organic photoelectricity such as organic solar cells, proper polymer donor materials are selected for matching, and the efficiency of a photovoltaic device can reach 13.2% under standard sunlight.

Description

Technical Field

[0001] The present invention relates to the field of organic photoelectric technology, and in particular to a preparation method and application of an aggregation-induced luminescence electron acceptor material. Background Art

[0002] In recent years, the global energy crisis has primarily revolved around traditional fossil fuels. Rising energy prices have led to global power shortages, pressure on industrial production, and disruptions to people's lives. Environmental pollution and the greenhouse effect caused by the use of fossil fuels pose significant challenges to the human environment. Vigorously promoting the development and utilization of renewable energy is a powerful measure to alleviate the energy crisis and improve the living environment. Solar energy is a key renewable energy source, and the development of organic solar cells has garnered widespread attention worldwide. Compared to other photovoltaic technologies, bulk heterojunction organic solar cells (BHJs), which combine polymer donors and electron acceptors, are currently attracting significant attention due to their advantages: lightweight, flexibility, and suitability for fabricating large-area flexible devices and self-powered wearable devices. These unique advantages hold broad application prospects. After years of development, particularly with the discovery of fused-ring electron acceptors such as ITIC and Y6, the photovoltaic efficiency of organic solar cells has exceeded 20% under standard sunlight and is expected to increase further. The photoluminescence quantum yield (PLQY) of traditional electron acceptor materials is very low. Aggregation-induced emission (AIE) is an optical phenomenon that breaks the traditional pattern of fluorescence reduction caused by aggregation in fluorescent materials. Materials with aggregation-induced emission properties exhibit significantly enhanced photoluminescence quantum yields in densely aggregated states, a property that makes them promising for broad application in a variety of optoelectronic devices. In organic solar cells, the introduction of electron acceptor materials with aggregation-induced emission properties can effectively enhance the photoluminescence quantum yield of the material, thereby improving the light absorption capacity and charge transfer efficiency, and thus significantly improving the energy conversion efficiency of the cell. In addition, aggregation-induced emission materials not only perform well in the photovoltaic field, but their high photoluminescence quantum yield also makes them suitable for optoelectronic devices such as OLEDs and phototherapy equipment, broadening the application range of the materials. Summary of the Invention

[0003] In view of the above-mentioned deficiencies or defects, the present invention aims to provide a preparation method and application of an electron acceptor material with aggregation-induced emission properties. By utilizing large steric hindrance side chains, the planarity of the conjugated main chain is maintained and molecular stacking is improved.

[0004] To achieve the above objectives, the present invention adopts the following technical solutions:

[0005] The present invention designs and synthesizes a receptor unit with thienothiophene, whose bulky side chains can produce significant steric hindrance, respectively preventing the central thiophene from participating in stacking and obtaining a highly planar conjugated skeleton. Its general structural formula is as followsFigure 1 As shown:

[0006] Here, R independently represents any one of a linear alkyl group and a branched alkyl group.

[0007] The present invention also provides a method for preparing the above-mentioned electron acceptor material having aggregation-induced luminescence properties. The general synthetic formula thereof is as follows: Figure 2 As shown:

[0008] The present invention also provides application of the acceptor material as an electron acceptor in an organic solar cell.

[0009] In summary, the present invention has the following advantages:

[0010] 1. The present invention provides an electron acceptor material with aggregation-induced luminescence (AIE). This material exhibits good aggregation in solution, high mobility, high electroluminescence efficiency, and good compatibility with the D18 donor. Existing near-infrared electron acceptor materials have very low photoluminescence quantum yields. In contrast, the present invention prepares an electron acceptor material with AIE, significantly improving its photoluminescence quantum yield.

[0011] 2. This invention designs a thienothiophene receptor molecule. Compared to existing non-fused-ring receptor molecules, the receptor unit of this invention incorporates triisopropylbenzene side chains into the central core, maintaining the planarity of the conjugated backbone while also providing significant steric hindrance for effective π-π stacking between IC groups.

[0012] 3. The present invention provides a method for synthesizing receptor molecules based on thienothiophene, which is simple to operate and significantly reduces purification costs.

[0013] The invention provides an organic photovoltaic cell prepared by using the acceptor molecule and a donor material, and also provides the photovoltaic efficiency of the molecule.

[0014] It should be understood that the advantages of the present invention will be described in the following description, and the following detailed description is exemplary and explanatory. The objectives and other advantages of the present invention can be achieved and obtained through the structures specifically pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments:

[0016] Figure 1 This is the general structural formula of the electron acceptor material for aggregation-induced luminescence of the present invention.

[0017] Figure 2 This is the general formula for synthesizing the electron acceptor material for aggregation-induced luminescence of the present invention.

[0018] Figure 3 This is the synthesis route of the electron acceptor material for aggregation-induced luminescence of the present invention.

[0019] Figure 4 The graph is a current density and voltage (JV) curve of the electron acceptor material and donor (D18) of the aggregation-induced luminescence of the present invention.

[0020] Figure 5 The figure is a graph showing the external quantum efficiency (EQE) of the electron acceptor material and the donor (D18) for aggregation-induced luminescence of the present invention.

[0021] Figure 6 These are emission spectra of the aggregation-induced luminescence electron acceptor material of the present invention at different volume ratios of water.

[0022] Figure 7 These are the photovoltaic device parameters of the aggregation-induced luminescence electron acceptor material and donor D18 under standard sunlight. DETAILED DESCRIPTION

[0023] The following will describe the embodiments of the present invention in detail with reference to the accompanying drawings and examples, so that the invention can fully understand how to apply technical means to solve technical problems in previous years and achieve the technical effects, and implement them accordingly. It should be noted that as long as there is no conflict, the various features in the various embodiments of the present invention can be combined with each other, and the resulting technical solutions are all within the scope of protection of the present invention.

[0024] Example 1:

[0025] The present invention discloses an aggregation-induced luminescence electron acceptor material, the synthesis route of which is as follows: Figure 3 As shown:

[0026] Synthesis of Compound 2: Compound 1 (1000 mg, 3.36 mmol), (2,4,6-triisopropylphenyl)boronic acid (3335 mg, 13.44 mmol), and potassium phosphate (K3PO4) (3566 mg, 16.80 mmol) were dissolved in toluene (50 mL). Tris(dibenzylideneacetone)dipalladium (156 mg, 0.17 mmol) and 2-dicyclohexylphosphino-2',6'-dimethoxybiphenyl (S-Phos) (140 mg, 0.34 mmol) were then added under a nitrogen atmosphere. The reaction mixture was refluxed at 120°C for 24 hours. The mixture was extracted with dichloromethane, and the organic phase was dried over anhydrous MgSO4, filtered, and evaporated under reduced pressure. The crude product was purified by silica gel column chromatography using petroleum ether / dichloromethane (1:1) as the eluent to yield a white solid (83%, 1520 mg). 1HNMR (600MHz, CDCl3) δ7.10(s,4H),7.03(s,2H),2.97(m,2H),2.74(m,4H),1.33(d,J=6.9Hz,12H),1.14(dd,J=6.9,2.1Hz,24H). 13 C NMR (151MHz, CDCl3) δ148.72,148.03,140.89,133.18,129.42,124.39,120.87,34.30,30.66,24.82,24.34,24.04.MS(TOF,C 36 H 48 S2):m / z 540.52.

[0027] Synthesis of Compound 3: Compound 2 (1000 mg, 1.84 mmol) was reacted with N-bromosuccinimide (NBS) (982 mg, 5.52 mmol) in a mixed solvent of chloroform (30 mL) and acetic acid (30 mL) in the dark at room temperature overnight. The reaction mixture was then poured into methanol (200 mL), filtered, and dried under vacuum to yield a white solid (1125 mg, 87%). 1 HNMR (600MHz, CDCl3) δ7.10 (s, 4H), 2.97 (m, 2H), 2.60 (m, 4H), 1.33 (d, J = 6.9Hz, 12H), 1.19 (d, J = 6.9Hz, 12H). 13 C NMR (151MHz, CDCl3) δ149.59,147.79,138.18,134.06,126.99,121.20,112.52,34.27,31.04,24.79,24.29,23.97.MS(TOF,C 36 H 46 Br2S2):m / z 701.48.

[0028] Synthesis of Compound 4: Compound 3 (500 mg, 0.71 mmol) and (4-(2-ethylhexyl)thiophen-2-yl)trimethyltin (589 mg, 1.64 mmol) were mixed in toluene and purged with nitrogen for 5 minutes. Pd(PPh3)4 (82 mg, 0.071 mmol) was then added, and the mixture was refluxed at 110°C overnight. The mixture was extracted with dichloromethane, and the organic phase was dried over anhydrous MgSO4, filtered, and evaporated under reduced pressure. The crude product was purified by silica gel column chromatography using petroleum ether / dichloromethane = 10:1 as eluent to obtain the product as a yellow solid (523 mg, 79%). 1H NMR (600MHz, CDCl3) δ7.15(s,4H),6.60(s,4H),3.01(m,2H),2.82-2.73(m,4H),2.35(m,4H) ),1.37(m,14H),1.18(m,28H),1.04(m,12H),0.86(t,J=7.0Hz,6H),0.78(t,J=7.5Hz,6H). 13 C NMR (151MHz, CDCl3) δ149.66,147.97,141.70,139.05,136.92,134.48,128.56,125.97,121.52,120.69,40.17,34.38 ,34.32,32.42,31.04,30.92,28.84,25.46,25.28,24.82,24.32,24.16,24.00,23.86,22.96,14.08,10.76.MS(TOF,C 60 H 84 S4):m / z 932.49.

[0029] Synthesis of Compound 5: Vilsmeier reagent was prepared by stirring POCl3 (0.3 mL) in DMF (1.2 mL) at 0°C for 30 minutes. This reagent was added dropwise to a solution of compound 4 (200 mg, 0.21 mmol) in ultra-dry 1,2-dichloroethane (20 mL) at 0°C under a nitrogen atmosphere. The mixture was refluxed at 85°C for 12 hours. The mixture was then poured into ice water (30 mL) and neutralized with saturated NaHCO3 solution, followed by stirring for 2 hours. The organic layer was separated, washed with saturated brine, dried over anhydrous magnesium sulfate, filtered, and evaporated under reduced pressure. The crude product was purified by silica gel column chromatography using petroleum ether / dichloromethane (1:2) as the eluent to yield the product as a yellow solid (189 mg, 91%). 1 H NMR (600MHz, CDCl3) δ9.82(s,2H),7.17(s,4H),6.59(s,2H),3.01(m,2H),2.65(m,8H),1.39-1.33(m ,14H),1.23(m,16H),1.15(m,12H),1.07-0.99(m,12H),0.84(t,J=7.0Hz,6H),0.78(t,J=7.4Hz,6H). 13C NMR (151MHz, CDCl3) δ181.52,151.96,150.63,147.54,145.31,141.18,136.93,134.68,132.48,128.08,127 .30,122.05,41.27,34.43,32.46,31.16,28.76,25.55,25.25,24.12,23.92,22.89,14.01,10.69.MS(TOF,C 62 H 84 O2S4): m / z 989.52. Synthesis of compound 6: Compound 5 (200 mg, 0.20 mmol), 2-(2-bromo-6-oxo-5,6-dihydro-4H-cyclopenta[b]thiophene-4-ylidene)malononitrile (225 mg, 0.80 mmol), chloroform (30 mL) and pyridine (0.2 mL) were mixed and stirred at 60 ° C for 5 days. Methanol (40 mL) was subsequently added to cause the crude product to precipitate. The precipitate was filtered and further purified by silica gel chromatography using chloroform as eluent to obtain a black solid product (215 mg, 71%). 1 H NMR(600MHz, CDCl3)8.59(d,J=10.3Hz,2H),7.95(s,1H),7.31(s,1H),7.23(s,4H),6.59(d,J=4.0Hz,2H),3.05(m,2H),2.75-2. 55(m,8H),1.40(d,J=6.8Hz,15H),1.19(d,J=6.7Hz,27H),1.06(d,J=6.6Hz,12H),0.84(t,J=6.7Hz,6H),0.76(t,J=7.3Hz,6H). 13 C NMR (151MHz, CDCl3) δ179.01,158.97,156.50,150.86,149.77,149.73,147.4 8,142.85,135.59,134.07,132.89,132.71,131.38,127.93,127.65,125.94,1 23.86,122.13,114.15,114.04,77.18,76.93,76.68,41.51,34.64,34.10,32 .28,31.29,28.73,25.34,25.16,24.10,23.91,22.86,13.89,10.55.MS(TOF,C 82 H 90 Br2N4O4S6): m / z 1510.77. Example 2:

[0030] Photovoltaic performance test of compound 6 electron acceptor material and donor (D18).

[0031] To investigate the photovoltaic performance of this acceptor, the present invention selected a suitable donor, D18, and employed a forward device structure of ITO / TIPD / active layer / PDINO / Al. Hole mobility was measured using the SCLC method, and the hole mobility was measured using an ITO / PEDOT:PSS / active layer / Au device structure.

[0032] Figure 4 This is the current density and voltage (JV) curve of the electron acceptor material of compound 6 and the donor (D18).

[0033] Implementation Example 3:

[0034] The present invention selects a suitable donor D18 and adopts a forward device structure of ITO / TIPD / active layer / PDINO / Al to measure the external quantum efficiency.

[0035] Figure 5 This is the external quantum efficiency (EQE) curve of compound 6, electron acceptor material and donor (D18).

[0036] Implementation Example 4:

[0037] Aggregation-induced emission performance test of compound 6 electron acceptor material.

[0038] In order to study the aggregation-induced emission properties of the receptor, the present invention selected compound 6 to test the emission at different volume ratios of water.

[0039] Figure 6 These are the emission spectra of compound 6 at different volume ratios of water.

[0040] Implementation Example 5:

[0041] Figure 7 The photovoltaic device parameters of the electron acceptor material of compound 6 and the donor D18 under standard sunlight. The photovoltaic performance of the acceptor molecule: open circuit voltage is 1.090V, short circuit current density is 18.57mAcm -2 and a fill factor of 65.39%, thus obtaining an outstanding photovoltaic efficiency of 13.20%.

Claims

1. A preparation method and application of an aggregation-induced luminescence electron acceptor material, characterized in that The general structural formula of the material is shown in Figure 1: Wherein, R represents any one of the following groups having 1 to 30 carbon atoms: linear alkyl, branched alkyl, chloroalkyl, arylalkyl, heteroalkyl, alkenyl, and arylalkyl. X1 represents any one of the following groups: alkylthiophene, alkoxythiophene, alkylbenzene ring, alkoxybenzene ring, alkylheterocycle, and alkoxyheterocycle. X2 represents any one of the following groups: cyanoindanone, halogenated cyanoindanone, and cyanothiophenoindanone.

2. The compound according to claim 1, characterized in that: In the heteroalkyl group, heteroatoms include oxygen, sulfur, nitrogen and silicon atoms.

3. The compound according to claim 1, characterized in that: The aromatic alkyl group or the one containing oxygen, sulfur or carbon is a 4-9 membered aromatic ring.

4. The compound according to claim 1, characterized in that: Examples of X1 include the following units: ...wherein, M1 and M2 represent linear alkyl, branched alkyl, chloroalkyl, aromatic alkyl, heteroalkyl, alkenyl, or aralkyl groups having 1 to 20 carbon atoms. M1 and M2 may be the same or different.

5. The compound according to claim 1, characterized in that: Examples of X2 include the following units: Wherein, M1 and M2 may be the same or different and are respectively selected from a hydrogen atom, a halogen atom, and an ester group or a fluoroalkyl group having 1 to 20 carbon atoms.

6. The method for preparing the electron acceptor material for aggregation-induced emission according to any one of claims 1 to 5, characterized in that The following steps are involved: As shown in Figure 2.

7. Application of the aggregation-induced luminescence electron acceptor material according to any one of claims 1 to 5 in organic solar cells, organic light-emitting diodes, cell imaging, drug tracking, portable electronic devices, and dual-band responsive devices of visible light and near-infrared light.

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