Electrochromic device and method for manufacturing the same

Abstract

The application provides an electrochromic device and a preparation method thereof, relates to the technical field of electrochromic technology, and discloses a dye switch molecule with a liquid crystal similar structure and an electrolyte molecule with a liquid crystal similar structure, wherein the dye switch molecule and the electrolyte molecule both have long alkyl chains, rigid phenyl groups and edge polarity groups contained in liquid crystal molecules, so that both of them have very good solubility in liquid crystals. The electrochromic device prepared by using the dye switch molecule and the electrolyte molecule designed in the application can adjust the ionic conductivity of the device in a temperature control or light control mode, has better rapid coloring performance and better long memory effect, and has good cycle stability.

Description

Technical Field

[0001] This invention relates to the field of electrochromic technology, and more specifically, to an electrochromic device and its preparation method. Background Technology

[0002] Electrochromism refers to the reversible changes in the structure, spectrum, and color of a substance under the stimulation of an electric field, through its own oxidation-reduction reaction. Electrochromic displays, with their adjustable colors, wide viewing angles, low operating voltage, and memory effect, promise to significantly reduce the energy consumption of electronic displays. The memory effect refers to the fact that information conversion requires very little electricity, and the information can be retained for a period of time after the voltage is removed, without the need for continuous power supply. Due to its extremely energy-saving characteristics, memory effect electrochromic displays are considered a very practical technology, with significant implications for scenarios such as mobile billboards and short-term (approximately ten minutes) refresh displays.

[0003] Currently, in-situ controllable ion transport in electrochromic devices is a difficult technology to achieve. Typically, for electrochromic devices, rapid coloring and long memory effect are two contradictory characteristics. Rapid coloring requires rapid ion transport within the system, while long memory effect requires slow or no ion transport. Therefore, it is difficult to achieve both rapid coloring and long memory effect simultaneously in electrochromic devices. To balance this contradiction, existing technologies usually sacrifice one characteristic based on performance requirements; for example, devices with slow coloring can achieve a long memory effect, while devices with fast coloring are unlikely to achieve a long memory effect. To achieve both rapid coloring and long memory effect in electrochromic devices, a dynamically adjustable ion transport environment is needed. This environment must provide a rapid ion transport channel when the device changes color rapidly, and provide a channel that hinders ion transport when the device needs to maintain its original color. Therefore, a dynamically controllable material is needed to serve as the ion transport environment.

[0004] Liquid crystals are an intermediate phase between solids and liquids, often referred to as liquid crystals. They combine the continuity and fluidity of liquids with the anisotropy of crystals, exhibiting typical optical (Δn) and electrical (Δε) anisotropy and sensitive multi-field (mechanical, thermal, optical, electrical, and magnetic) response characteristics. Liquid crystals are excellent tunable optoelectronic functional materials; their dielectric anisotropy covers a broad frequency band from ultraviolet to microwaves, and they possess birefringence. Under the influence of an applied electric or magnetic field, liquid crystal molecules can be reoriented, altering the birefringence and enabling dynamic tunability. Therefore, researchers have proposed using liquid crystals as the ion transport environment for electrochromic systems to obtain electrochromic devices that combine rapid coloring and long memory effects. However, although electrochromic devices prepared in this way can achieve rapid coloring and long memory effect, their performance needs further improvement and their cycle performance is poor. In addition, most electrochromic devices with memory effect are based on multilayer structures. The long memory effect is achieved by constructing a three-layer structure of ion transport layer, electrochromic layer and ion storage layer, which makes the manufacturing process too complicated. Summary of the Invention

[0005] The problem solved by this invention is at least one of the following: (1) The rapid coloring performance and long memory effect performance of electrochromic devices obtained by using liquid crystal as the ion transport environment of electrochromic system need to be further improved, and the cycle performance of the devices is poor. (2) How to obtain an electrochromic device with both better rapid coloring ability and better long memory effect through a simple process.

[0006] To solve the above problems, the present invention provides an electrochromic device, comprising a dye switch molecule, an electrolyte molecule and a liquid crystal, wherein the dye switch molecule is selected from one or more of formulas (1)-(4);

[0007]

[0008]

[0009] In formulas (1)-(4), R1, R2, R3 and R4 are independently selected from H, -CH3, -CH2CH3, -CH2CH2CH3 and -CH2CH2CH2CH3 respectively; R5, R6 and R7 are independently selected from H and the groups shown in formulas (5)-(7) respectively, where m and n are integers greater than or equal to 0;

[0010]

[0011] R8 to R 32The electrolyte molecule is independently selected from any one of hydrogen, hydroxyl, halogen, amino, C1-C24 alkyl, C1-C24 substituted alkyl, C1-C24 alkoxy, C1-C24 alkylamino, C6-C24 aryl, and C7-C24 groups containing both an aromatic ring and an alkane; the electrolyte molecule is selected from one or more of formulas (8)-(11);

[0012]

[0013]

[0014] In equations (8)-(11), p is an integer greater than or equal to 0, and R 1 R 2 R 3 and R 4 Each group is independently selected from H and one of the groups shown in formulas (5)-(7);

[0015] R 5 To R 20 Each group is independently selected from any one of hydrogen, hydroxyl, halogen, amino, C1-C24 alkyl, C1-C24 substituted alkyl, C1-C24 alkoxy, C1-C24 alkylamino, C6-C24 aryl, and groups between C7 and C24 that simultaneously contain an aromatic ring and an alkane;

[0016] X - Selected from arsenic ions, azide ions, bromide ions, chloride ions, fluoride ions, hydride ions, iodide ions, nitrogen ions, oxygen ions, phosphorus ions, sulfide ions, peroxide ions, arsenate ions, arsenite ions, borate ions, bromate ions, hypobromate ions, carbonate ions, bicarbonate ions, hydroxide ions, chlorate ions, perchlorate ions, chlorite ions, hypochlorite ions, chromate ions, iodate ions, nitrate ions, nitrite ions, phosphorus ions. One of the following: acid radical ion, phosphite ion, hydrogen phosphate ion, dihydrogen phosphate ion, manganate ion, permanganate ion, sulfate ion, thiosulfate ion, hydrogen sulfate ion, sulfite ion, bisulfite ion, persulfate ion, silicate ion, metasilicate ion, aluminosilicate ion, acetate ion, formate ion, oxalate ion, hydrogen oxalate ion, hydrogen sulfide ion, tellurium ion, amino anion, cyanate ion, thiocyanate ion, and cyanide ion.

[0017] Compared with existing technologies, this invention designs and synthesizes a dye-switching molecule with a liquid crystal-like structure. Specifically, this dye-switching molecule contains long alkyl chains, rigid phenyl groups, and edge polar groups found in liquid crystal molecules. Based on the principle of "like dissolves like," this dye-switching molecule exhibits excellent compatibility with liquid crystals, perfectly combining the alignment characteristics of liquid crystals with the low-voltage stimulus response characteristics of dye-switching molecules. Furthermore, this dye-switching molecule possesses both an electroacid structure and a dye structure, and it meets the structural requirements of intramolecular PCET molecules. Specifically, it contains both an electron-transferring p-phenylenediamine structure and a pH-sensitive fluorinated alkyl group with a high molar absorption coefficient to accept protons and switch colors, resulting in low-voltage initiation characteristics and good cycling stability. Simultaneously, to meet the conductivity requirements of electrochromic materials, this invention designs and synthesizes an electrolyte molecule with a liquid crystal-like structure as the electrolyte. Specifically, this electrolyte molecule contains long alkyl chains, rigid phenyl groups, and edge polar groups found in liquid crystal molecules, and it also exhibits excellent solubility in liquid crystals. Experiments have shown that the electrochromic device fabricated using the dye-switching molecules and electrolyte molecules designed in this invention possesses both excellent rapid coloring performance and a superior long-term memory effect, along with good cycle stability. Furthermore, the dye-switching molecules and electrolyte molecules designed in this invention can be applied to most liquid crystal systems. In addition, the electrochromic device obtained in this invention allows for adjustment of its ionic conductivity through temperature control or light control, thereby enabling performance regulation.

[0018] The present invention also provides a method for preparing the electrochromic device as described above, comprising:

[0019] Step S1: Mix the dye switching molecules, electrolyte molecules, counter electrode material and liquid crystal evenly to obtain an electrochromic solution;

[0020] Step S2: Assemble the electrochromic solution with transparent conductive glass to obtain an electrochromic device.

[0021] Compared with the prior art, the electrochromic device prepared by the method provided by the present invention has better rapid coloring performance and better long memory effect, as well as good cycle stability. In addition, the preparation process of the present invention is simpler, only requiring the raw materials to be prepared into a solution and injected into a transparent conductive glass box. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the fabrication process of the electrochromic device in an embodiment of the present invention;

[0023] Figure 2 A comparison of the visible spectrum of the electrochromic device prepared in Application Example 1 before and after applying a positive voltage;

[0024] Figure 3 The graph shows the change of spectral absorption over time for the electrochromic device prepared in Application Example 1 when a positive voltage is applied.

[0025] Figure 4 The graph shows the change in spectral absorption over time of the electrochromic device prepared in Application Example 1 during the process of applying a positive voltage to the device fading.

[0026] Figure 5 The graph shows the cycle stability test results of the electrochromic device prepared in Application Example 1.

[0027] Figure 6 For comparison, the visible spectrum of the electrochromic device prepared in Application Example 1 before and after applying a positive voltage is shown in the comparison diagram.

[0028] Figure 7 To illustrate the comparative application example 2, here is a graph showing the change in spectral absorption over time during the device fading process after a positive voltage is applied.

[0029] Figure 8 The graph shows the ionic conductivity test results of the electrochromic device prepared in Application Example 2 at different temperatures.

[0030] Figure 9 The graph shows the reflectivity of the electrochromic device prepared in Example 2 at room temperature after applying a positive voltage (1.2V, 10s) and removing the voltage as a function of time.

[0031] Figure 10 The graph shows the reflectivity of the electrochromic device prepared in Example 2 at 80°C after applying a positive voltage (1.2V, 10s) and removing the voltage over time.

[0032] Figure 11 A polarizing microscope image of the electrochromic device prepared in Example 3 under sunlight;

[0033] Figure 12 A polarizing microscope image of the electrochromic device prepared in Example 3 under ultraviolet light;

[0034] Figure 13 This is a schematic diagram showing the arrangement of liquid crystals in the electrochromic device prepared in Application Example 3 under different illuminations. Detailed Implementation

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0036] Electrolyte materials are essential for electrochromic devices. However, there are currently no electrolytes that are highly soluble in liquid crystals. Furthermore, the dye-switching molecules and electrolytes (inorganic or organic metal salts containing metal ions, tetraalkyl quaternary ammonium salts, and ionic liquids) used in existing electrochromic devices have poor solubility in liquid crystals. As a result, the rapid coloring performance and long memory effect performance of liquid crystal-based electrochromic devices need to be further improved, and the cycling performance of the devices is also poor.

[0037] Based on the above considerations, the present invention provides an electrochromic device comprising a dye switch molecule, an electrolyte molecule and a liquid crystal, wherein the dye switch molecule is selected from one or more of formulas (1)-(4);

[0038]

[0039] In formulas (1)-(4), R1, R2, R3 and R4 are independently selected from H, -CH3, -CH2CH3, -CH2CH2CH3 and -CH2CH2CH2CH3 respectively; R5, R6 and R7 are independently selected from H and the groups shown in formulas (5)-(7) respectively, where m and n are integers greater than or equal to 0;

[0040]

[0041]

[0042] R8 to R 32 Each group is independently selected from any one of hydrogen, hydroxyl, halogen, amino, C1-C24 alkyl, C1-C24 substituted alkyl, C1-C24 alkoxy, C1-C24 alkylamino, C6-C24 aryl, and groups between C7 and C24 that simultaneously contain an aromatic ring and an alkane;

[0043] The electrolyte molecules are selected from one or more of formulas (8)-(11);

[0044]

[0045] In equations (8)-(11), p is an integer greater than or equal to 0, and R 1 R 2 R 3 and R 4 Each group is independently selected from H and one of the groups shown in formulas (5)-(7);

[0046] R 5 To R 20Each group is independently selected from any one of hydrogen, hydroxyl, halogen, amino, C1-C24 alkyl, C1-C24 substituted alkyl, C1-C24 alkoxy, C1-C24 alkylamino, C6-C24 aryl, and groups between C7 and C24 that simultaneously contain an aromatic ring and an alkane;

[0047] X - Selected from arsenic ions, azide ions, bromide ions, chloride ions, fluoride ions, hydride ions, iodide ions, nitrogen ions, oxygen ions, phosphorus ions, sulfide ions, peroxide ions, arsenate ions, arsenite ions, borate ions, bromate ions, hypobromate ions, carbonate ions, bicarbonate ions, hydroxide ions, chlorate ions, perchlorate ions, chlorite ions, hypochlorite ions, chromate ions, iodate ions, nitrate ions, nitrite ions, phosphorus ions. One of the following: acid radical ion, phosphite ion, hydrogen phosphate ion, dihydrogen phosphate ion, manganate ion, permanganate ion, sulfate ion, thiosulfate ion, hydrogen sulfate ion, sulfite ion, bisulfite ion, persulfate ion, silicate ion, metasilicate ion, aluminosilicate ion, acetate ion, formate ion, oxalate ion, hydrogen oxalate ion, hydrogen sulfide ion, tellurium ion, amino anion, cyanate ion, thiocyanate ion, and cyanide ion.

[0048] It should be noted that intermolecular proton-coupled electron transfer (PCET) suffers from problems such as low coupling efficiency of proton and electron transfer, slow solubility, and slow molecular / ion diffusion and aggregation rates. Intramolecular proton-coupled electron transfer is a good option to overcome the aforementioned defects associated with intermolecular proton-coupled electron transfer. However, careful material design is required to develop efficient intramolecular PCET. Intramolecular proton-coupled electron transfer requires the molecular structure to include an electroactive part for transferring electrons, an intramolecular hydrogen-bonded group for establishing a PCET channel, and a pH-sensitive subunit with a high molar absorption coefficient to accept protons and switch colors. Obviously, as shown in equations (1)-(4), the dye switch molecule designed in this invention meets the structural requirements of an intramolecular PCET molecule. That is, the dye switch molecule designed in this invention contains a p-phenylenediamine structure for transferring electrons and a pH-sensitive fluoryl group with a high molar absorption coefficient to accept protons and switch colors.

[0049] Liquid crystal molecules typically possess long alkyl chains, rigid phenyl groups, and peripheral polar groups. Therefore, in this invention, similar structures are introduced into the dye-switching molecule and the electrolyte molecule. This invention designs and synthesizes a dye-switching molecule with a liquid crystal-like structure, namely, the long alkyl chains, rigid phenyl groups, and peripheral polar groups found in liquid crystal molecules. Based on the principle of "like dissolves like," this dye-switching molecule exhibits excellent compatibility with liquid crystals, perfectly combining the alignment characteristics of liquid crystals with the low-voltage stimulus-response characteristics of dye-switching molecules. Furthermore, this dye-switching molecule possesses both an electroacidic structure and a dye structure, and it meets the structural requirements of intramolecular PCET molecules. Specifically, it contains both an electron-transferring p-phenylenediamine structure and a pH-sensitive fluorinated alkyl group with a high molar absorption coefficient to accept protons and switch colors, resulting in low-voltage start-up characteristics and good cycling stability. Meanwhile, to meet the conductivity requirements of electrochromic materials, this invention designed and synthesized an electrolyte molecule with a liquid crystal-like structure. Specifically, this electrolyte molecule possesses the long alkyl chains, rigid phenyl groups, and peripheral polar groups found in liquid crystal molecules, and also exhibits excellent solubility in liquid crystals. Experiments revealed that the electrochromic device fabricated using the dye-switching molecule and electrolyte molecule designed in this invention possesses both superior rapid coloring performance and excellent long-term memory effect, along with good cycle stability. Furthermore, the electrochromic device obtained in this invention allows for adjustment of its ionic conductivity through temperature or light control, thereby enabling performance regulation.

[0050] In some embodiments of the present invention, the dye switching molecule is, by way of example, shown in formulas (M1), (M3) and (M5);

[0051]

[0052] In some embodiments of the present invention, the electrolyte molecules are, by way of example, shown in formulas (M2), (M4) and (M6);

[0053]

[0054] Based on the arrangement of liquid crystal molecules, liquid crystals can be classified into nematic liquid crystals, smectic liquid crystals, and cholesteric liquid crystals. In this embodiment of the invention, these three types of liquid crystals were selected. Nematic liquid crystals include 5CB, 7CB, 8CB, 5CT, CB15, E48, 8OCB, SLC1717, E7, and SLC7011-100, etc.; smectic liquid crystals include 11 types such as SA, SB, SC, SD, SE, SF, SG, SH, SI, SJ, and SK, with specific molecules such as azobenzene ether and 2-(4-(4-pentylcyclohexyl)phenoxy)ethane-1-ol, etc.; cholesteric liquid crystals include fatty acid salts, cellulose, DNA, most cholesterol compounds, and chiral dopants, such as cholesteryl benzoate and cholesterol benzoate, etc.

[0055] Preferably, the liquid crystal is a smectic liquid crystal. Smectic liquid crystals tend to form anisotropic single domains, which facilitates the generation of long-range ion transport channels and is beneficial for obtaining electrochromic devices with better performance.

[0056] In some embodiments of the present invention, the electrochromic device further includes a counter electrode material, which includes one of p-benzoquinone, coenzyme Q0, methoxybenzoquinone, 2,6-di-tert-butyl-p-benzoquinone, and 2,5-di-tert-butyl-p-benzoquinone. The counter electrode material is used to balance the charge of the electrochromic device.

[0057] In some embodiments of the present invention, in the electrochromic device, the mass ratio of the dye switching molecule, the electrolyte molecule, the counter electrode material and the liquid crystal is (10-40):(100-200):(10-60):500.

[0058] like Figure 1 As shown, the present invention also provides a method for fabricating the electrochromic device as described above, comprising:

[0059] Step S1: Mix the dye switching molecules, electrolyte molecules, counter electrode material and liquid crystal evenly to obtain an electrochromic solution;

[0060] Step S2: Assemble the electrochromic solution with transparent conductive glass to obtain an electrochromic device.

[0061] Compared with existing technologies, the electrochromic device prepared by the method provided in this invention exhibits both superior rapid coloring performance and superior long-term memory effect, as well as good cycle stability. Furthermore, the preparation process of this invention is simpler, requiring only the preparation raw materials to be formulated into a solution and injected into a transparent conductive glass container.

[0062] Specifically, assembling the electrochromic solution with transparent conductive glass to obtain an electrochromic device includes: using the transparent conductive glass to make a box, injecting the electrochromic solution into the box, and obtaining the electrochromic device.

[0063] In some embodiments of the present invention, the surface of the transparent conductive glass is modified with a photosensitive material; the photosensitive material is selected from azobenzene, spiropyran, and Steinhaus compound. In this embodiment, the structure of the photosensitive molecules can be changed by different light sources, thereby realizing the conversion of liquid crystal molecules from parallel alignment to vertical alignment, thereby regulating the ion transport rate to achieve the switching of the electrochromic device between high conductivity and low conductivity states.

[0064] The present invention will be further described below with reference to specific embodiments.

[0065] Example 1: Synthesis of dye switching molecule M1

[0066] 1.1 Preparation of compound A1

[0067] Aminorhodamine (1.374 g, 3 mmol), 4,4′-dibromobiphenyl (624 mg, 2 mmol), and anhydrous toluene (10 mL) were added to a dry reaction flask under nitrogen protection. Then, under stirring, o-phenylphenol (34 mg, 0.2 mmol) and cuprous iodide (19 mg, 0.1 mmol) were added to the reaction flask. Finally, potassium phosphate (849 mg, 4 mmol) was added to the reaction flask. The mixture was heated to 100 °C and refluxed under nitrogen protection for 12 h. After the reaction system cooled to room temperature, insoluble matter was removed by filtration. The filter cake was washed with dichloromethane, and the filtrate was collected and concentrated. The product was separated by column chromatography (eluent: dichloromethane and methanol) to obtain compound A1 in 58% yield. The reaction formula for the synthesis of compound A1 is as follows:

[0068]

[0069] 1.2 Preparation of dye-switching molecule M1

[0070] Compound A1 (689 mg, 1 mmol), n-hexylamine (264 mL, 2 mmol), and anhydrous toluene (10 mL) were added to a dry reaction flask under nitrogen protection. Then, palladium acetate (11.2 mg, 0.05 mmol) and XPhos (72 mg, 0.15 mmol) were added to the reaction flask under stirring. Finally, potassium carbonate (221 mg, 1.6 mmol) was added to the reaction flask. The mixture was heated to 90 °C and refluxed under nitrogen protection for 48 h. After the reaction system cooled to room temperature, insoluble matter was removed by filtration. The filter cake was washed with dichloromethane, and the filtrate was collected and concentrated. The product was separated by column chromatography (eluent: dichloromethane and methanol) to obtain dye switch molecule M1 in 64% yield. The reaction formula for the synthesis of dye switch molecule M1 is as follows:

[0071]

[0072] The characterization data of dye-switching molecule M1 are as follows: 1 H NMR (400MHz, DMSO-d6) δ8.53(s,1H),7.60(d,J=8.3Hz,2H),7.51(t,J=7.6Hz,1H),7.43( dd,J=8.4,6.0Hz,4H),7.27(d,J=8.3Hz,1H),6.64(dd,J=8.8,2.7Hz,4H),6.49-6.42(m, 5H),5.73(t,J=5..6Hz,1H),3.43-3.35(m,8H),3.04(q,J=6.6Hz,2H),1.57(m,J=7.3Hz, 2H), 1.37 (m, J = 7.4Hz, 2H), 1.34-1.27 (m, 4H), 1.10 (m, J = 6.9Hz, 12H), 0.93-0.86 (t, 3H).

[0073] Example 2, Electrolyte molecule M2

[0074] 2.1 Preparation of compound B1

[0075] 4-Bromo-4'-n-heptylbiphenyl (331 mg, 1 mmol) and ethylene glycol (7 mL) were added to a dry reaction flask under nitrogen protection. Then, copper chloride (8.52 mg, 0.05 mmol) was added to the reaction flask under stirring. Finally, potassium carbonate (414 mg, 3 mmol) was added to the reaction flask. The mixture was heated to 135 °C and refluxed under nitrogen protection for 48 h. After the reaction system was cooled to room temperature, insoluble matter was removed by filtration. The filter cake was washed with dichloromethane, and the filtrate was collected and concentrated. The product was separated by column chromatography (eluent: petroleum ether and ethyl acetate) to give compound B1 in 53% yield. The reaction formula for the synthesis of compound B1 is as follows:

[0076]

[0077] 2.2 Preparation of compound B2

[0078] Compound B1 (312 mg, 1 mmol) and dichloromethane (3 mL) were added to a flask and cooled to 0 °C. While stirring, p-toluenesulfonyl chloride (267 mg, 1.4 mmol) was added to the flask. Finally, triethylamine (0.3 mL) and DMAP (6.1 mg, 0.05 mmol) were added to the flask. The mixture was stirred at room temperature for 12 hours. After the reaction was complete, the mixture was filtered, and the filtrate was collected. The organic phase was extracted three times with saturated brine. The organic phase was collected, concentrated, and the product was separated by column chromatography (eluting with petroleum ether and ethyl acetate) to obtain compound B2 in 83% yield. The reaction formula for the synthesis of compound B2 is as follows:

[0079]

[0080] 2.3 Preparation of electrolyte molecule M2

[0081] At 0°C, sodium hydride (43 mg, 1.8 mmol) and anhydrous tetrahydrofuran (3 mL) were added to a two-necked round-bottom flask. Compound N-1 (43 mg, 1 mmol) was dissolved in anhydrous tetrahydrofuran and then added dropwise to the flask. The mixture was stirred for 2 h. Then, compound B2 (482 mg, 1.1 mmol) was dissolved in anhydrous tetrahydrofuran and then added dropwise to the flask. The mixture was stirred for 2 h, heated to 50°C, and reacted for 24 h. After the reaction system cooled to room temperature, the insoluble matter was removed by filtration. The filter cake was washed with dichloromethane, and the filtrate was collected and concentrated. The product was separated by column chromatography (eluent: petroleum ether and ethyl acetate) to obtain electrolyte molecule M2 in 72% yield. The structural formula of compound N-1 is as follows:

[0082]

[0083] The reaction equation for the synthesis of electrolyte molecule M2 is as follows:

[0084]

[0085] The characterization data of electrolyte molecule M2 are as follows: 1H NMR (400MHz, Chloroform-d) δ7.52(d,J=6.2Hz,2H),7.45(d,J=7.7Hz,2H),7.23(d,J=7.8Hz,2H),6.93(d,J=8.2Hz,2H),4.15(t,2H),3.96(t,2H ), 3.88 (t, 2H), 3.47 (t, 2H), 3.37 (m, J = 7.6Hz, 8H), 2.63 (m, J = 8.1Hz, 2H), 1.69 (m, J = 23.5Hz, 4H), 1.31 (m, J = 8.8Hz, 13H), 0.88 (t, J = 7.0Hz, 3H).

[0086] Example 3: Synthesis of dye switching molecule M3

[0087] 3.1 Preparation of compound A2

[0088] Trinitrophthalic anhydride (5.02 g, 26 mmol), 3-dimethylaminophenol (6.86 g, 50 mmol), and chlorobenzene (50 mL) were added to a reaction flask and stirred. Trifluoromethanesulfonic acid (3.90 g, 26 mmol) was then added as a catalyst. The mixture was heated to 135 °C and refluxed under nitrogen protection for 48 h. After cooling to room temperature, chlorobenzene was removed by rotary evaporation. The residue was dissolved in dichloromethane, and the organic phase was washed with sodium hydroxide solution at pH 13 to remove trifluoromethanesulfonic acid, intermediate keto acids, and unreacted 3-dimethylaminophenol. The organic phase was dried, concentrated, and the product was separated by column chromatography (eluent: dichloromethane and methanol) to obtain compound A2 in 50% yield. The reaction formula for the synthesis of compound A2 is as follows:

[0089]

[0090] 3.2 Preparation of compound A3

[0091] Compound A2 (431 mg, 1 mmol), palladium on carbon (55% water content, 17 mg), and ethyl acetate (4 mL) were mixed to obtain a first mixture. Hypophosphoric acid (50% water content, 198 mg), sodium hypophosphite monohydrate (477 mg, 4.5 mmol), and water (4 mL) were mixed to obtain a second mixture. The first and second mixtures were added to a reaction flask, heated to 85 °C, and stirred for 3.5 h. After the reaction system cooled to room temperature, the aqueous phase was extracted with ethyl acetate and dichloromethane, respectively. The organic phases were then combined, dried with anhydrous sodium sulfate, concentrated, and the product was separated by column chromatography (eluting with petroleum ether, ethyl acetate, and triethylamine) to obtain compound A3 in 70% yield. The reaction formula for the synthesis of compound A3 is as follows:

[0092]

[0093] 3.3 Preparation of compound A4

[0094] Compound A3 (689 mg, 1 mmol), 4,4'-dibromobiphenyl (624 mg, 2 mmol), and tert-butanol (10 mL) were added to a reaction flask under nitrogen protection. Palladium acetate (11.2 mg, 0.05 mmol) and XPhos (72 mg, 0.15 mmol) were added to the flask with stirring. Finally, potassium carbonate (221 mg, 1.6 mmol) was added. The mixture was heated to 90 °C and refluxed under nitrogen protection for 40 h. After cooling to room temperature, the insoluble matter was removed by filtration. The filter cake was washed with dichloromethane, and the filtrate was collected and concentrated. The product was separated by column chromatography (eluent: dichloromethane and methanol) to obtain compound A4 in 48% yield. The reaction formula for the synthesis of compound A4 is as follows:

[0095]

[0096] 3.4 Preparation of dye-switching molecule M3

[0097] Compound A4 (633 mg, 1 mmol), octadecylamine (351 mg, 1.3 mmol), and tert-butanol (10 mL) were added to a dry reaction flask under nitrogen protection. Then, palladium acetate (11.2 mg, 0.05 mmol) and XPhos (72 mg, 0.15 mmol) were added to the reaction flask under stirring. Finally, potassium carbonate (221 mg, 1.6 mmol) was added to the reaction flask. The mixture was heated to 90 °C and refluxed under nitrogen protection for 36 h. After the reaction system cooled to room temperature, insoluble matter was removed by filtration. The filter cake was washed with dichloromethane, and the filtrate was collected and concentrated. The product was separated by column chromatography using methanol / dichloromethane as the eluent to obtain dye switch molecule M3 in 70% yield. The reaction formula for the synthesis of dye switch molecule M3 is as follows:

[0098]

[0099] Example 4: Synthesis of electrolyte molecule M4

[0100] Compound N-2 (540 mg, 3 mmol), compound B3 (730 mg, 2 mmol), and anhydrous dimethylformamide (10 mL) were added to a dry reaction flask under nitrogen protection. Then, 8-hydroxyquinoline (29 mg, 0.2 mmol) and cuprous iodide (19 mg, 0.1 mmol) were added to the reaction flask under stirring. Finally, potassium phosphate (849 mg, 4 mmol) was added to the reaction flask. The mixture was heated to 110 °C and refluxed under nitrogen protection for 48 h. After the reaction system cooled to room temperature, insoluble matter was removed by filtration. The filter cake was washed with dichloromethane, and the filtrate was collected and concentrated. The product was separated by column chromatography (eluent: methanol and dichloromethane) to obtain electrolyte molecule M4 in 58% yield. The structural formula of compound N-2 is as follows:

[0101]

[0102] The structural formula of compound B3 is as follows:

[0103]

[0104] The reaction formula for the synthesis of dye switch molecule M4 is as follows:

[0105]

[0106] Example 5: Synthesis of dye switching molecule M5

[0107] 5.1 Preparation of compound A5

[0108] Trinitrophthalic anhydride (5.02 g, 26 mmol), N,N-dibutyl-3-aminophenol (11.05 g, 50 mmol), and chlorobenzene (50 mL) were added to a reaction flask. After stirring, trifluoromethanesulfonic acid (3.90 g, 26 mmol) was added as a catalyst. The mixture was heated to 135 °C and refluxed under nitrogen protection for 48 h. After the reaction system cooled to room temperature, chlorobenzene was removed by rotary evaporation. The residue was dissolved in dichloromethane. The organic phase was washed with sodium hydroxide solution at pH 13 to remove trifluoromethanesulfonic acid, intermediate keto acid, and unreacted N,N-dibutyl-3-aminophenol. The organic phase was dried, concentrated, and the product was separated by column chromatography (eluent: dichloromethane and methanol) to obtain compound A5 in 60% yield. The reaction formula for the synthesis of compound A5 is as follows:

[0109]

[0110] 5.2 Preparation of compound A6

[0111] Compound A5 (600 mg, 1 mmol), palladium on carbon (55% water content, 17 mg), and ethyl acetate (4 mL) were mixed to obtain a first mixture. Hypophosphoric acid (50% water content, 198 mg), sodium hypophosphite monohydrate (477 mg, 4.5 mmol), and water (3 mL) were mixed to obtain a second mixture. The first and second mixtures were added to a reaction flask, heated to 85 °C, and stirred for 3.5 h. After the reaction system cooled to room temperature, the aqueous phase was extracted with ethyl acetate and dichloromethane, respectively. The organic phases were then combined, dried with anhydrous sodium sulfate, concentrated, and the product was separated by column chromatography (eluting with petroleum ether, ethyl acetate, and triethylamine) to obtain compound A6 in 80% yield. The reaction formula for the synthesis of compound A6 is as follows:

[0112]

[0113] 5.3 Preparation of compound A7

[0114] Compound A6 (1.71 g, 3 mmol), 4,4′-dibromo-1,1′-bicyclohexyl (648 mg, 2 mmol), and anhydrous toluene (10 mL) were added to a reaction flask under nitrogen protection. Then, 8-hydroxyquinoline (29 mg, 0.2 mmol) and cuprous iodide (19 mg, 0.1 mmol) were added to the flask with stirring. Finally, potassium phosphate (849 mg, 4 mmol) was added. The mixture was heated to 110 °C and refluxed under nitrogen protection for 24 h. After the reaction system cooled to room temperature, insoluble matter was removed by filtration. The filter cake was washed with dichloromethane, and the filtrate was collected and concentrated. The product was separated by column chromatography (eluent: dichloromethane and methanol) to obtain compound A7 in 75% yield. The reaction formula for the synthesis of compound A7 is as follows:

[0115]

[0116] 5.4 Preparation of dye-switching molecule M5

[0117] Compound A7 (813 mg, 1 mmol), n-butylamine (95 mg, 1.3 mmol), and tert-butanol (10 mL) were added to a dry reaction flask under nitrogen protection. Then, palladium acetate (11.2 mg, 0.05 mmol) and XPhos (72 mg, 0.15 mmol) were added to the reaction flask under stirring. Finally, potassium carbonate (221 mg, 1.6 mmol) was added to the reaction flask. The mixture was heated to 90 °C and refluxed under nitrogen protection for 36 h. After the reaction system cooled to room temperature, insoluble matter was removed by filtration. The filter cake was washed with dichloromethane, and the filtrate was collected and concentrated. The product was separated by column chromatography (eluent: dichloromethane and methanol) to obtain dye switch molecule M5 in 62% yield. The reaction formula for the synthesis of dye switch molecule M5 is as follows:

[0118]

[0119] Example 6: Synthesis of electrolyte molecule M4

[0120] Compound N-3 (291 mg, 1 mmol), compound B4 (496 mg, 1.2 mmol), and anhydrous dimethylformamide (10 mL) were added to a dry reaction flask under nitrogen protection. Then, copper chloride (8.52 mg, 0.05 mmol) was added to the reaction flask under stirring. Finally, potassium carbonate (414 mg, 3 mmol) was added. The mixture was heated to 135 °C and refluxed under nitrogen protection for 48 h. After the reaction system cooled to room temperature, insoluble matter was removed by filtration. The filter cake was washed with dichloromethane, and the filtrate was collected and concentrated. The product was separated by column chromatography (eluent: petroleum ether and ethyl acetate) to obtain electrolyte molecule M6 in 68% yield. The structural formula of compound N-3 is as follows:

[0121]

[0122] The structural formula of compound B4 is as follows:

[0123]

[0124] The reaction formula for the synthesis of dye switch molecule M6 is as follows:

[0125]

[0126] Application Example 1

[0127] (1) Mix the dye switching small molecule M1 (10mg), electrolyte molecule M2 (100mg), p-benzoquinone (10mg) and smectic liquid crystal p-azo anisole (500mg) and stir evenly at 60℃ to obtain an electrochromic solution.

[0128] (2) After heating the electrochromic solution (50 μL) to 90°C, it is injected into a box made of transparent conductive glass through capillary action and naturally cooled to room temperature to obtain an electrochromic device; wherein the length and width of the box are both 2 cm and the thickness is 50 μm.

[0129] Application Example 2

[0130] (1) The dye switch molecule M3 (30mg), electrolyte molecule M4 (200mg), coenzyme Q0 (60mg) and smectic liquid crystal p-azo anisole (500mg) were mixed and stirred evenly at 80°C to obtain an electrochromic solution.

[0131] (2) After heating the electrochromic solution (50 μL) to 90°C, it is injected into a box made of transparent conductive glass through capillary action and naturally cooled to room temperature to obtain an electrochromic device; wherein the length and width of the box are both 2 cm and the thickness is 30 μm.

[0132] Application Example 3

[0133] (1) The dye switch molecule M5 (40mg), electrolyte molecule M6 (150mg), 2,6-di-tert-butyl-p-benzoquinone (40mg) and smectic liquid crystal 2-(4-(4-pentylcyclohexyl)phenoxy) ethanol-1-ol (500mg) were mixed and stirred at 60°C to obtain an electrochromic solution.

[0134] (2) After heating the electrochromic solution (50 μL) to 90°C, it is injected into a box made of transparent conductive glass through capillary action and naturally cooled to room temperature to obtain an electrochromic device; wherein, the surface of the transparent conductive glass is modified with a photosensitive material, the photosensitive material is azobenzene, the length and width of the box are both 2 cm, and the thickness is 50 μm.

[0135] Comparative Application Example 1

[0136] (1) The dye-switching molecule C (40 mg), the electrolyte tetrabutylammonium hexafluorophosphate (150 mg), 2,6-di-tert-butyl-p-benzoquinone (40 mg), and the smectic liquid crystal p-azo anisole (500 mg) were mixed and stirred at 60 °C to obtain an electrochromic solution; the structural formula of the dye-switching molecule C is as follows:

[0137]

[0138] (2) After heating the electrochromic solution (50 μL) to 90°C, it is injected into a box made of transparent conductive glass through capillary action and naturally cooled to room temperature to obtain an electrochromic device; the box has a length and width of 2 cm and a thickness of 50 μm.

[0139] Comparative Application Example 2

[0140] The difference from Application Example 1 is that the smectic liquid crystal p-azobenzene in step (1) is replaced with an equal mass of polymer gel matrix, which is composed of PC and PMMA.

[0141] Experimental Example

[0142] At room temperature, the solubility of dye switching molecules M1, M3, M5, C, electrolyte molecules M2, M4, M6, and tetrabutylammonium hexafluorophosphate in smectite liquid crystals was tested. The results are shown in Table 1. As can be seen from Table 1, the dye switching molecules and electrolyte molecules provided in this invention have good solubility in liquid crystals.

[0143] Table 1

[0144] sample Solubility (wt%) M1 8.1 M3 8.5 M5 8.4 C Less than 0.2 M 2 29.8 M4 30.1 M 6 30.5 Tetrabutylhexammonium phosphate Less than 2

[0145] A positive voltage (1.2V, 10s) was applied to the electrochromic device fabricated in Example 1, and the visible spectrum of the electrochromic device before and after the application of the positive voltage was measured. The results are shown in [Figure 1]. Figure 2 ,from Figure 2 It can be seen that the electrochromic device is colorless when no voltage is applied, and turns magenta when a positive voltage (1.2V, 10s) is applied. The absorption peak in the visible region is located at 560nm, and the absorbance reaches 0.7. Using 560nm as a constant wavelength, the visible region kinetic spectrum of the electrochromic device was measured during the application of the positive voltage (1.2V, 10s) and after the removal of the positive voltage. The results are shown in [Figure number missing]. Figure 3 and Figure 4 ,from Figure 3 It can be seen that when a positive voltage (1.2V, 10s) is applied, the electrochromic device rapidly colors, and its color does not immediately fade after the applied positive voltage is removed; from Figure 4 It can be seen that when the applied positive voltage is removed, the colored state of the electrochromic device continues for five minutes before slowly fading back to the initial value, with a recovery time exceeding 20 minutes. A "coloring-fading" cycle experiment was conducted on this electrochromic device, and the results are shown below. Figure 5 ,from Figure 5 It can be seen that after more than 2000 color-fading cycles, the electrochromic device showed no significant performance degradation, indicating that it has good cycle stability. In summary, the electrochromic device prepared in Application Example 1 possesses both excellent rapid coloring performance and excellent long memory effect, and exhibits good cycle stability.

[0146] A positive voltage (1V, 10s) was applied to the electrochromic device prepared in Comparative Application Example 1, and the visible spectrum of the electrochromic device before and after the application of the positive voltage was measured. The results are shown in [Figure Number]. Figure 6 ,from Figure 6 It can be seen that the electrochromic device turns magenta when a positive voltage (1V, 10s) is applied, and a weak absorption peak appears in the visible spectrum at around 560nm. However, the absorbance change is only 0.05. This slight color change is difficult to distinguish with the naked eye and cannot be applied to real life. This is mainly because the dye switching molecule C and the electrolyte molecule tetrabutylammonium hexafluorophosphate have poor solubility in the smectic liquid crystal p-azobenzene ether, which results in poor performance of the electrochromic device.

[0147] The visible region kinetic spectra of the electrochromic device fabricated in Application Example 2 were compared during the application of a positive voltage (1.2V, 10s) and after the positive voltage was removed. The results are shown in [Figure Number]. Figure 7 ,from Figure 7 It can be seen that the electrochromic device can change color rapidly when a positive voltage is applied, and quickly fades back to its initial colorless state after the positive voltage is removed. Therefore, the electrochromic device prepared in Comparative Application Example 2 only possesses rapid coloring performance, but does not have a good long-term memory effect.

[0148] In Application Example 2, the electrochromic solution is a phase change material with a phase transition temperature (liquid crystal state to liquid state) of approximately 60°C. The ionic conductivity of the electrochromic device fabricated in Application Example 2 was tested at different temperatures, and the results are shown in [Figure 2]. Figure 8 As the phase transition occurs, the ionic conductivity of this electrochromic device also undergoes a step change, thus exhibiting temperature-controlled conductivity characteristics. At room temperature, the reflectivity of the device under a positive voltage (1.2V, 10s) and after the voltage is removed are plotted against time; the results are shown in the figure. Figure 9 ,from Figure 9 It can be seen that the electrochromic device changes from colorless to magenta when a positive voltage is applied, and the color can be maintained for two hours after the voltage is removed, exhibiting a long memory effect. The reflectivity of the device under positive voltage (1.2V, 10s) at 80℃ is shown in the graphs. Figure 10 ,from Figure 10It can be seen that when a positive voltage is applied to the electrochromic device, it changes from colorless to magenta, and the coloring speed is faster than at room temperature. After the voltage is removed, it completely fades back to the initial colorless state, and does not have a long memory effect. Therefore, by utilizing the phase transition characteristics of liquid crystals, a dynamic combination of rapid color change and long memory effect can be achieved by adjusting the temperature. The specific implementation method is as follows: A positive voltage is applied to the electrochromic device at 80℃ to make it color rapidly; after the positive voltage is applied, it is placed in an ice-water bath for rapid cooling, which blocks the ion transport channels of the device, and the colored state is maintained for a long time (two hours); the electrochromic device is heated to 80℃, and its color fades rapidly.

[0149] Under sunlight, the electrochromic device prepared in Example 3 was characterized using polarizing microscopy. The results are shown in [Figure Number]. Figure 11 Under ultraviolet light, the electrochromic device prepared in Example 3 was characterized by polarizing microscopy, and the results are shown in [Figure 1]. Figure 12 ;from Figure 11 and Figure 12 As can be seen, under sunlight, the polarized light microscope image of this electrochromic device appears in color, indicating that the liquid crystals exhibit a regularly arranged phase state, providing a fast channel for ion transport. When irradiated with ultraviolet light, the polarized light microscope image of the electrochromic device appears grayish-black, indicating that the liquid crystal molecules are continuously transitioning to a vertical phase, eventually exhibiting a near-vertical phase state, blocking ion transport, and the color-changing state can be retained for up to 20 hours. It is evident that the electrochromic device can switch between high conductivity and low conductivity states using different light sources. The mechanism of these phenomena is explained below, as follows... Figure 13 As shown, under sunlight, the liquid crystal molecules align parallel to the transparent conductive glass substrate. At this point, the liquid crystal molecules provide a rapid transport channel for ions, which exhibit high ion transport speeds. When the device is irradiated with ultraviolet light, a structural change in the photosensitive material is induced. Due to the highly sensitive nature of liquid crystals to external stimuli, the alignment of the liquid crystal molecules changes after the conformational change, shifting from an initial state parallel to the transparent conductive glass substrate to a state perpendicular to it. This blocks the ion transport channel, thus achieving long-term retention of the color-changing state. After the ultraviolet light is removed, due to the recovery of the photosensitive material structure, the liquid crystal molecules also change from a state perpendicular to the transparent conductive glass substrate to a state parallel to it.

[0150] It should be noted that Figure 2 and Figure 6 The initial state series represents the visible spectrum of the electrochromic device before a positive voltage is applied, while the other series represents the visible spectrum of the electrochromic device when a positive voltage is applied or after the voltage is applied (for liquid crystal devices). Figure 3 , Figure 4 , Figure 7 , Figure 9 and Figure 10The "Remove Voltage" arrow indicates the time point when the voltage is removed, and the "1.2V 10s" arrow indicates the time point when the positive voltage is applied.

[0151] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. An electrochromic device, characterized in that, It includes dye-switching molecules, electrolyte molecules and liquid crystals, wherein the dye-switching molecules are selected from one or more of formulas (1)-(4); ； （1） ； （2） ； （3） ； （4） In equations (1)-(4), R1, R2, R3 and R4 are independently selected from one of -CH3, -CH2CH3 and -CH2CH2CH2CH3, respectively; R5 and R6 are both H, and R7 is selected from C6H. 13 C 18 H 37 And one of C4H9; R8 to R 32 Each group is independently selected from any one of hydrogen, hydroxyl, halogen, amino, C1-C24 alkyl, C1-C24 alkoxy, C1-C24 alkylamino, C6-C24 aryl, and groups between C7 and C24 that simultaneously contain an aromatic ring and an alkane; The electrolyte molecules are selected from one or more of formulas (8)-(11); ； （8） ； （9） ； （10） ； （11） In equations (8)-(11), p is 1, R 1 Selected from C7H 15 C9H 19 and C 12 H 25 One of them, R 2 R 3 and R 4 All are ethyl; R 5 To R 20 Each group is independently selected from any one of hydrogen, hydroxyl, halogen, amino, C1-C24 alkyl, C1-C24 alkoxy, C1-C24 alkylamino, C6-C24 aryl, and groups between C7 and C24 that simultaneously contain an aromatic ring and an alkane; X - It is selected from one of chloride ions, tetrafluoroborate ions, and hexafluorophosphate ions.

2. The electrochromic device according to claim 1, characterized in that, The structural formulas of the dye switch molecules are shown in formulas (M1), (M3) and (M5); ； （M1） ； （M3） （M5）。 3. The electrochromic device according to claim 1, characterized in that, The structural formulas of the electrolyte molecules are shown in formulas (M2), (M4) and (M6); ； （M2） ； （M4） （M6）。 4. The electrochromic device according to claim 1, characterized in that, The liquid crystal is a smectic liquid crystal.

5. The electrochromic device according to claim 1, characterized in that, It also includes the electrode material.

6. The electrochromic device according to claim 5, characterized in that, The counter electrode material includes one of p-benzoquinone, coenzyme Q0, methoxybenzoquinone, 2,6-di-tert-butyl-p-benzoquinone, and 2,5-di-tert-butyl-p-benzoquinone.

7. The electrochromic device according to claim 5, characterized in that, In the electrochromic device, the mass ratio of the dye switching molecule, the electrolyte molecule, the counter electrode material, and the liquid crystal is (10-40):(100-200):(10-60):

500.

8. A method for preparing an electrochromic device as described in any one of claims 5-7, characterized in that, include: Step S1: Mix the dye switching molecules, electrolyte molecules, counter electrode material and liquid crystal evenly to obtain an electrochromic solution; Step S2: Assemble the electrochromic solution with transparent conductive glass to obtain an electrochromic device.

9. The method for preparing the electrochromic device as described in claim 8, characterized in that, Assembling the electrochromic solution with transparent conductive glass to obtain an electrochromic device includes: using the transparent conductive glass to make a box, injecting the electrochromic solution into the box, and obtaining the electrochromic device.

10. The method for preparing the electrochromic device as described in claim 9, characterized in that, The surface of the transparent conductive glass is modified with a photosensitive material; the photosensitive material is selected from one of azobenzene, spiropyran and Steinhaus adduct.

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