Electrochromic material as well as preparation method and application thereof

Abstract

The invention provides an electrochromic material as well as a preparation method and application thereof. The structural formula of the electrochromic material is as follows: # imgabs0 #, wherein AR1 is a group as shown in R1 or R3; aR2 is a group represented by R2 or R6; aR3 is selected from any one group represented by R3, R4 and R5; aR4 is a group represented by R2, n is the degree of polymerization, and n is 4-35. According to the invention, four high-performance electrochromic materials TTP, TEP, TPP and PBP3P which can be processed in a solution are prepared by adopting an arylation polycondensation process; the electrochromic material is used as a raw material, a high-performance patterned electrochromic camouflage device is prepared by means of mask spraying, and nylon filter membranes with different apertures are introduced into a device structure to adjust the transmittance of the device so as to achieve a better camouflage effect.

Description

Technical Field

[0001] The present invention relates to the technical field of electrochromic materials, and in particular to an electrochromic material and a preparation method and application thereof. Background Art

[0002] The application of electrochromic materials in the field of military camouflage has become a research hotspot. Among them, solution-processable electrochromic materials, as a type of organic electrochromic materials, have received widespread attention due to their diverse and simple film-forming methods. At present, the electrochromic performance of solution-processable electrochromic materials and devices used in military camouflage is poor.

[0003] Chinese patent documents disclose "an electrochromic material and a preparation method thereof, and an electrochromic device and a preparation method thereof", and its publication number is CN102952538A. The electrochromic material comprises an n-type electrochromic material, a p-type electrochromic material, a polymer matrix and a first solvent, wherein the n-type electrochromic material is a viologen compound, and the n-type electrochromic material and the p-type electrochromic material are embedded in the polymer matrix to form a gel electrochromic material. This invention obtains a gel electrochromic material by embedding the n-type electrochromic material and the p-type electrochromic material in a polymer matrix, but the electrochromic performance of the material is still poor when applied in the field of military camouflage, and needs to be further improved. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the purpose of the present invention is to provide an electrochromic material and a preparation method and application thereof, so as to solve the problem that the existing solution-processable electrochromic materials and devices used for military camouflage have poor electrochromic performance.

[0005] In order to achieve the above-mentioned object and other related objects, the present invention provides an electrochromic material, the structural formula of which is shown below: Wherein: AR1 is a group represented by R1 or R3; AR2 is a group represented by R2 or R6; AR3 is selected from any one of R3, R4 and R5; AR4 is the group represented by R2; n is the degree of polymerization, which refers to the number of consecutive repeating units in the polymer molecular chain, and n ranges from 4 to 35; The structural formula of the groups represented by R1, R2, R3, R4, R5 and R6 is as follows:

[0006] Preferably, AR1 is the group represented by R1, AR2 is the group represented by R2, AR3 is the group represented by R5, x, y, z and w are all 1; n is 20 to 35, and the structural formula of the electrochromic material is as shown in Formula I:

[0007] More preferably, the electrochromic material TTP shown in Formula I has an optical contrast ratio of 34.08% at a wavelength of 535 nm, a coloring time of 0.77 s, and a fading time of 0.87 s.

[0008] Preferably, AR1 is the group represented by R1, AR2 is the group represented by R2, AR3 is the group represented by R4, x, y, z and w are all 1; n is 10 to 20, and the structural formula of the electrochromic material is shown in Formula II:

[0009] More preferably, the electrochromic material TEP shown in Formula II has an optical contrast ratio of 40.27% at a wavelength of 545 nm, a coloring time of 0.90 s, and a fading time of 0.64 s.

[0010] Preferably, AR1 is the group represented by R1, AR2 is the group represented by R2, AR3 is the group represented by R3, x, y, z and w are all 1; n is 15 to 25, and the structural formula of the electrochromic material is shown in Formula III:

[0011] More preferably, the electrochromic material TPP shown in Formula III has an optical contrast of 45.52% at a wavelength of 540nm, a coloring time of 0.65s, and a fading time of 0.38s; after 3000 cycles at a step voltage of 0V and 0.9V, the optical contrasts of the three materials can maintain 60.92%, 87.83% and 68.52% of the initial contrast.

[0012] Preferably, AR1 is a group represented by R3, AR2 is a group represented by R6, AR3 is a group represented by R3, x, y and z are all 1, w is 3; n is 4 to 8, and the structural formula of the electrochromic material is shown in Formula IV:

[0013] More preferably, the electrochromic material PBP3P shown in Formula IV has an optical contrast of 43.56% at a wavelength of 640nm, a coloring time of 0.90s, and a fading time of 0.56s; after 3000 cycles at a step voltage of 0V and 1.0V, the optical contrast of the three electrochromic films can maintain 88.25% of the initial contrast.

[0014] The present invention also provides a method for preparing an electrochromic material (TTP) as shown in formula I, using N,N-bis(4-bromophenyl)-4-butylaniline as shown in formula V, 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene as shown in formula VI and 2,5-dibromothiophene as shown in formula VII as raw materials, reacting at 110-135° C. under a protective atmosphere to generate the electrochromic material as shown in formula I;

[0015] Preferably, under nitrogen protection, N,N-bis(4-bromophenyl)-4-butylaniline, 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-B][1,4]dioxepene, 2,5-dibromothiophene, potassium carbonate, pivalic acid, an appropriate amount of Pd(OAc)2 and anhydrous DMAc are added to a Schlenk tube, reacted at 130° C. for 15 to 17 hours, and post-treated to obtain the electrochromic material TTP shown in Formula I.

[0016] Preferably, the ratio of the amount of the feed materials of 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-B][1,4]dioxepene to N,N-bis(4-bromophenyl)-4-butylaniline is 2:1.

[0017] Preferably, the ratio of the amount of the 2,5-dibromothiophene to the amount of N,N-bis(4-bromophenyl)-4-butylaniline is 1:1.

[0018] Preferably, the ratio of the amount of the anhydrous potassium carbonate to the amount of N,N-bis(4-bromophenyl)-4-butylaniline fed is (4-6):1.

[0019] Preferably, the ratio of the amount of the pivalic acid to the amount of N,N-bis(4-bromophenyl)-4-butylaniline fed is (0.01-0.1):1.

[0020] Preferably, the ratio of the amount of Pd(OAc)2 to the amount of N,N-bis(4-bromophenyl)-4-butylaniline is (0.01-0.05):1.

[0021] Preferably, the added volume of the anhydrous DMAc is 40 to 80 mL / g based on the mass of N,N-bis(4-bromophenyl)-4-butylaniline.

[0022] Preferably, the post-reaction treatment method is: adding the reaction solution to methanol, filtering the mixture with a Buchner funnel, washing the filter cake with methanol, wrapping the filter cake with filter paper and extracting polymers of different polymerization degrees therein with a Soxhlet extractor, during which solvents with different solubility are replaced, and the order of using the solvents is methanol, acetone, petroleum ether, and chloroform, and the part extracted with chloroform is rotary evaporated to remove the solvent to obtain the electrochromic material TTP shown in formula I.

[0023] The present invention also provides a method for preparing an electrochromic material (TEP) shown in formula II, using N,N-bis(4-bromophenyl)-4-butylaniline shown in formula V, 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene shown in formula VI and 2,5-dibromo-3,4-vinyldioxythiophene shown in formula VIII as raw materials, reacting at 110-135° C. under a protective atmosphere to generate the electrochromic material shown in formula II;

[0024] Preferably, under nitrogen protection, N,N-bis(4-bromophenyl)-4-butylaniline, 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-B][1,4]dioxepene, 2,5-dibromo-3,4-vinyldioxythiophene, potassium carbonate, pivalic acid, an appropriate amount of Pd(OAc)2 and anhydrous DMAc are added to a Schlenk tube, reacted at 130° C. for 15 to 17 hours, and post-treated to obtain the electrochromic material TEP shown in formula II.

[0025] Preferably, the ratio of the amount of the feed materials of 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-B][1,4]dioxepene to N,N-bis(4-bromophenyl)-4-butylaniline is 2:1.

[0026] Preferably, the ratio of the amount of the 2,5-dibromo-3,4-vinyldioxythiophene to the amount of N,N-bis(4-bromophenyl)-4-butylaniline is 1:1.

[0027] Preferably, the ratio of the amount of anhydrous potassium carbonate to the amount of N,N-bis(4-bromophenyl)-4-butylaniline fed is (4-6):1.

[0028] Preferably, the ratio of the amount of the pivalic acid to the amount of N,N-bis(4-bromophenyl)-4-butylaniline fed is (0.01-0.1):1.

[0029] Preferably, the ratio of the amount of Pd(OAc)2 to the amount of N,N-bis(4-bromophenyl)-4-butylaniline is (0.01-0.05):1.

[0030] Preferably, the added volume of the anhydrous DMAc is 40 to 80 mL / g based on the mass of N,N-bis(4-bromophenyl)-4-butylaniline.

[0031] Preferably, the post-reaction treatment method is: adding the reaction solution to methanol, filtering the mixture with a Buchner funnel, washing the filter cake with methanol, wrapping the filter cake with filter paper and extracting polymers of different polymerization degrees therein with a Soxhlet extractor, during which solvents with different solubility are replaced, and the order of using the solvents is methanol, acetone, petroleum ether, and chloroform, and the part extracted with chloroform is rotary evaporated to remove the solvent to obtain the electrochromic material TEP shown in formula II.

[0032] The present invention also provides a method for preparing an electrochromic material (TPP) shown in formula III, wherein N,N-bis(4-bromophenyl)-4-butylaniline shown in formula V, 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene shown in formula VI and 6,8-dibromo-3,4-dihydro-3,3-dimethyl 2H-thieno[3,4-b][1,4]dioxepene shown in formula IX are used as raw materials, and the reaction is carried out at 110-135° C. under a protective atmosphere to produce the electrochromic material shown in formula III;

[0033] Preferably, under nitrogen protection, N,N-bis(4-bromophenyl)-4-butylaniline, 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-B][1,4]dioxepene, 6,8-dibromo-3,4-dihydro-3,3-dimethyl 2H-thieno[3,4-B][1,4]dioxepene, potassium carbonate, pivalic acid, an appropriate amount of Pd(OAc)2 and anhydrous DMAc are added to a Schlenk tube, reacted at 130° C. for 15 to 17 hours, and post-treated to obtain the electrochromic material TPP shown in formula III.

[0034] Preferably, the ratio of the amount of the feed materials of 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-B][1,4]dioxepene to N,N-bis(4-bromophenyl)-4-butylaniline is 2:1.

[0035] Preferably, the ratio of the amount of the 6,8-dibromo-3,4-dihydro-3,3-dimethyl 2H-thieno[3,4-B][1,4]dioxepin to the amount of N,N-bis(4-bromophenyl)-4-butylaniline is 1:1.

[0036] Preferably, the ratio of the amount of anhydrous potassium carbonate to the amount of N,N-bis(4-bromophenyl)-4-butylaniline is 4 to 6:1.

[0037] Preferably, the ratio of the amount of the pivalic acid to the amount of N,N-bis(4-bromophenyl)-4-butylaniline fed is (0.01-0.1):1.

[0038] Preferably, the ratio of the amount of Pd(OAc)2 to the amount of N,N-bis(4-bromophenyl)-4-butylaniline is (0.01-0.05):1.

[0039] Preferably, the added volume of the anhydrous DMAc is 40 to 80 mL / g based on the mass of N,N-bis(4-bromophenyl)-4-butylaniline.

[0040] Preferably, the post-reaction treatment method is: adding the reaction solution to methanol, filtering the mixture with a Buchner funnel, washing the filter cake with methanol, wrapping the filter cake with filter paper and extracting polymers of different polymerization degrees therein with a Soxhlet extractor, during which solvents with different solubility are replaced, and the order of using the solvents is methanol, acetone, petroleum ether, and chloroform, and the part extracted with chloroform is rotary evaporated to remove the solvent to obtain the electrochromic material TPP shown in formula III.

[0041] The present invention also provides a method for preparing an electrochromic material (PBP3P) as shown in formula IV, wherein 4,7-bis(3,3-dimethyl-3,4-dihydro-2H-thiophene[3,4-b][1,4]dioxopyran-6-yl)benzo[c][1,2,5]thiazole as shown in formula X, 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene as shown in formula VI and 6,8-dibromo-3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene as shown in formula XII are reacted to generate the electrochromic material as shown in formula IV;

[0042] Preferably, under nitrogen protection, 4,7-bis(3,3,-dimethyl-3,4-dihydro-2H-thiophene[3,4-b][1,4]dioxepin-6-yl)benzo[c][1,2,5]thiazole, 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin, 6,8-dibromo-3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin, potassium carbonate, pivalic acid, an appropriate amount of Pd(OAc)2 and anhydrous DMAc are added to a Schlenk tube, reacted at 130° C. for 3 to 8 hours, and post-treated to obtain the electrochromic material PBP3P shown in formula IV.

[0043] Preferably, the ratio of the amount of the feed material of 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene to 4,7-bis(3,3,-dimethyl-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepin-6-yl)benzo[c][1,2,5]thiazole is 1:1.

[0044] Preferably, the ratio of the amount of the feed material of 6,8-dibromo-3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene to 4,7-bis(3,3,-dimethyl-3,4-dihydro-2H-thiophene[3,4-b][1,4]dioxepin-6-yl)benzo[c][1,2,5]thiazole is 2:1.

[0045] Preferably, the ratio of the amount of potassium carbonate to the amount of 4,7-bis(3,3-dimethyl-3,4-dihydro-2H-thiophene[3,4-b][1,4]dioxopyran-6-yl)benzo[c][1,2,5]thiazole is (3-5):1.

[0046] Preferably, the ratio of the amount of the pivalic acid to the amount of 4,7-bis(3,3-dimethyl-3,4-dihydro-2H-thiophene[3,4-b][1,4]dioxopyran-6-yl)benzo[c][1,2,5]thiazole is (0.01-0.1):1.

[0047] Preferably, the ratio of the amount of Pd(OAc)2 to the amount of 4,7-bis(3,3-dimethyl-3,4-dihydro-2H-thiophene[3,4-b][1,4]dioxopyran-6-yl)benzo[c][1,2,5]thiazole is (0.01-0.05):1.

[0048] Preferably, the added volume of the anhydrous DMAc is 40 to 80 mL / g based on the mass of 4,7-bis(3,3-dimethyl-3,4-dihydro-2H-thiophene[3,4-b][1,4]dioxopyran-6-yl)benzo[c][1,2,5]thiazole.

[0049] Preferably, the post-reaction treatment method is: adding the reaction solution to methanol, filtering the mixture with a Buchner funnel, washing the filter cake with methanol, wrapping the filter cake with filter paper and extracting polymers of different polymerization degrees therein with a Soxhlet extractor, during which solvents with different solubility are replaced, and the order of using the solvents is methanol, acetone, petroleum ether, and chloroform, and the part extracted with chloroform is rotary evaporated to remove the solvent to obtain the electrochromic material PBP3P shown in formula IV.

[0050] The present invention also provides a use of the electrochromic material in preparing an electrochromic device.

[0051] The present invention provides a method for preparing an electrochromic device, comprising the following steps: The electrochromic material (TTP) represented by formula I, the electrochromic material (TEP) represented by formula II, and the electrochromic material (TPP) represented by formula III are sprayed on transparent conductive electrodes to prepare electrochromic films that can switch between red-yellow-green-high-transmittance states as working electrodes; The electrochromic material (PBP3P) shown in Formula IV is sprayed on a transparent conductive electrode to prepare an electrochromic film capable of switching between a green system and a high-transmittance state as a counter electrode; TTP and PBP3P, TEP and PBP3P, and TPP and PBP3P were assembled into red-yellow-green-green switching electrochromic devices, called TTP-PBP3P, TEP-PBP3P, and TPP-PBP3P, respectively.

[0052] The present invention provides a method for preparing a high-performance patterned electrochromic camouflage device, comprising the following steps: The electrochromic material (TTP) represented by formula I, the electrochromic material (TEP) represented by formula II, and the electrochromic material (TPP) represented by formula III are sequentially sprayed on the same transparent conductive electrode through a mask to prepare a patterned electrochromic film that can switch between red-yellow-green-high-transmittance states as a working electrode; The electrochromic material (PBP3P) shown in Formula IV is sprayed onto a transparent conductive electrode through a mask to prepare a patterned electrochromic film that can switch between a green system and a high-transmittance state as a counter electrode; When preparing a sandwich-structured electrochromic device, nylon filter membranes with different pore sizes are added to the electrolyte layer to prepare a high-performance patterned electrochromic camouflage device.

[0053] More preferably, the transparent electrode is selected from any one of ITO glass, ITO-PET and ITO-PEN.

[0054] More preferably, the pore size of the nylon filter membrane is selected from any one of 10 μm, 50 μm, 100 μm and 200 μm.

[0055] As described above, the present invention has the following beneficial effects: four high-performance solution-processable electrochromic materials TTP, TEP, TPP and PBP3P are prepared by an arylation polycondensation process; high-performance patterned electrochromic camouflage devices are prepared by mask spraying using the above electrochromic materials as raw materials, and nylon filter membranes with different pore sizes are introduced into the device structure to adjust the transmittance of the device to achieve a better camouflage effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 Synthetic routes for four solution-processable electrochromic materials.

[0057] Figure 2 CV curves of four electrochromic films.

[0058] Figure 3 UV-visible absorption spectra of four electrochromic films at different voltages.

[0059] Figure 4 Response time of four electrochromic films in different wavelength bands.

[0060] Figure 5 This is a stability test of four electrochromic films in different wavelength bands.

[0061] Figure 6 These are photos of four electrochromic films at different voltages.

[0062] Figure 7 The chromaticity of four electrochromic films at different voltages.

[0063] Figure 8 CV curves of three high-performance red-yellow-green-green switching electrochromic devices.

[0064] Fig. 9 These are the UV-visible absorption spectra of three high-performance red-yellow-green-green switching electrochromic devices at different voltages.

[0065] Fig.10 The response time of three high-performance red-yellow-green-green switching electrochromic devices at 650nm was tested.

[0066] Fig.11The stability of three high-performance red-yellow-green-green switching electrochromic devices was tested at 650nm.

[0067] Fig.12 Photos of three high-performance red-yellow-green-green switching electrochromic devices at different voltages.

[0068] Fig.13 The chromaticity of three high-performance red-yellow-green-green switching electrochromic devices at different voltages.

[0069] Fig.14 The transmittance curves at ±1V of nylon filters with different pore sizes added to three high-performance red-yellow-green-green switching electrochromic devices.

[0070] Fig.15 Photos of three high-performance red-yellow-green-green switching electrochromic devices with nylon filters of different pore sizes added at ±1V.

[0071] Fig.16 Photos of patterned electrochromic camouflage devices at different voltages. DETAILED DESCRIPTION

[0072] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.

[0073] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0074] In addition, it should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before or after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified; it should also be understood that the combination connection relationship between one or more devices / apparatuses mentioned in the present invention does not exclude the existence of other devices / apparatuses before or after the combination device / apparatus or the insertion of other devices / apparatuses between these explicitly mentioned two devices / apparatuses, unless otherwise specified. Moreover, unless otherwise specified, the numbering of each method step is only a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or the scope of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of the present invention without substantially changing the technical content.

[0075] The synthesis methods of the electrochromic materials in Examples 1 to 4 of the present application are specifically referred to Figure 1 The synthetic routes of four solution-processable electrochromic materials are shown.

[0076] Example 1 Synthesis of TTP (Ⅰ) Weigh N,N-bis(4-bromophenyl)-4-butylaniline (229.5 mg, 0.5 mmol), 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-B][1,4]dioxepene (440 mg, 1 mmol), 2,5-dibromothiophene (120.97 mg, 0.5 mmol), anhydrous potassium carbonate (345 mg, 2.5 mmol), pivalic acid (4.09 mg, 0.04 mmol) and Pd(OAc)2 (4.53 mg, 0.02 mmol) into a 15 mL Schlenk tube. Under nitrogen protection, add 15 mL of anhydrous DMAc, react at 130 °C for 15 h, and cool to room temperature.

[0077] The reaction solution is added to 300 ml of methanol, filtered with a Buchner funnel, and the filter cake is washed with methanol. The filter cake is wrapped with filter paper and then extracted with a Soxhlet extractor to extract polymers of different polymerization degrees. During the process, solvents with different dissolving powers are replaced in the order of methanol, acetone, petroleum ether, and chloroform. Finally, the part extracted with chloroform is rotary evaporated to remove the solvent to obtain TTP as shown in formula I, wherein n is 20 to 35.

[0078] Example 2 Synthesis of TEP (II) Weigh N,N-bis(4-bromophenyl)-4-butylaniline (229.5 mg, 0.5 mmol), 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-B][1,4]dioxepene (440 mg, 1 mmol), 2,5-dibromo-3,4-vinyldioxythiophene (150 mg, 0.5 mmol), anhydrous potassium carbonate (345 mg, 2.5 mmol), pivalic acid (4.09 mg, 0.04 mmol) and Pd(OAc)2 (4.53 mg, 0.02 mmol) into a 15 mL Schlenk tube. Under nitrogen protection, add 15 mL of anhydrous DMAc, react at 130 °C for 16 h, and cool to room temperature. The reaction solution is added to 300 ml of methanol, filtered with a Buchner funnel, and the filter cake is washed with methanol. The filter cake is wrapped with filter paper and polymers of different polymerization degrees are extracted with a Soxhlet extractor. During the process, solvents with different dissolving powers are replaced in the order of methanol, acetone, petroleum ether, and chloroform. Finally, the part extracted with chloroform is rotary evaporated to remove the solvent to obtain TEP as shown in formula II, where n is 10 to 20.

[0079] Example 3 Synthesis of TPP (III) Weigh N,N-bis(4-bromophenyl)-4-butylaniline (229.5 mg, 0.5 mmol), 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-B][1,4]dioxepene (440 mg, 1 mmol), 6,8-dibromo-3,4-dihydro-3,3-dimethyl 2H-thieno[3,4-B][1,4]dioxepene (171 mg, 0.5 mmol), anhydrous potassium carbonate (345 mg, 2.5 mmol), pivalic acid (4.09 mg, 0.04 mmol) and Pd(OAc)2 (4.53 mg, 0.02 mmol) into a 15 mL Schlenk tube. Under nitrogen protection, add 15 mL of anhydrous DMAc, react at 130 °C for 17 h, and cool to room temperature. The reaction solution was added into 300 ml of methanol, filtered with a Buchner funnel, and the filter cake was washed with methanol. The filter cake was wrapped with filter paper and polymers of different polymerization degrees were extracted with a Soxhlet extractor. During the process, solvents with different dissolving powers were replaced in the order of methanol, acetone, petroleum ether, and chloroform. Finally, the part extracted with chloroform was rotary evaporated to remove the solvent to obtain TPP as shown in formula III, where n is 15 to 25.

[0080] Example 4 Synthesis of PBP3P(IV) Weigh 4,7-bis(3,3-dimethyl-3,4-dihydro-2H-thienyl[3,4-b][1,4]dioxopyran-6-yl)benzo[c][1,2,5]thiazole (250.33 mg, 0.5 mmol), 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thienyl[3,4-b][1,4]dioxepene (220.34 mg, 0.5 mmol), 6,8-dibromo-3,3-bis(((2-ethylhexyl)oxy)methyl)- 1,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene (598.48 mg, 1 mmol), anhydrous potassium carbonate (345 mg, 2.5 mmol), pivalic acid (4.09 mg, 0.04 mmol) and Pd(OAc)2 (4.53 mg, 0.02 mmol) were added to a 15 mL Schlenk tube. Under nitrogen protection, 15 mL of anhydrous DMAc was added, and the reaction was carried out at 130 ° C for 5 h, and then cooled to room temperature. The reaction solution was added to 300 ml of methanol, filtered with a Buchner funnel, and the filter cake was washed with methanol. The filter cake was wrapped with filter paper and then extracted with a Soxhlet extractor to extract polymers of different polymerization degrees. During the process, solvents with different solubility were replaced. The order of solvent use was methanol, acetone, petroleum ether, and chloroform. Finally, the part extracted with chloroform was rotary evaporated to remove the solvent to obtain PBP3P as shown in formula IV, where n is 4 to 8.

[0081] Example 5 Preparation of electrochromic film 15 mg of TTP, TEP, TPP and PBP3P were respectively added into 10 ml sample bottles, 1 ml of chloroform was added thereto respectively, the solution was shaken to mix evenly, and then filtered using a microporous filter with a pore size of 0.45 μm, and then spin-coated on the conductive surface of 25*40 mm ITO glass using a spin coater (parameter setting: 1000 rpm / min, spin coating time 1 min) to obtain an electrochromic film.

[0082] Example 6 Performance Test of Electrochromic Film 1. Electrochemical testing of TTP, TEP, TPP and PBP3P The electrochemical test was performed using a Chenhua 660 electrochemical workstation with the following parameter settings: CV mode, scan rate of 50 / 100 / 200 / 300 / 500 mv / s, scan range of 0.0 V and 0.9 V (TTP, TEP and TPP), 0.0 V and 1.0 V (PBP3P). Figure 2As shown in the figure, the TTP, TEP, TPP and PBP3P electrochromic films all have electrochemical responses within the scanning range, and their CV curves have quasi-reversible redox behaviors. As the scanning speed increases, the peak current also gradually increases, proving that the film has good adhesion to the conductive substrate.

[0083] 2. Optical and electrochromic performance tests of TTP, TEP, TPP and PBP3P The optical and electrochromic performance tests were conducted using a Chenhua 660 electrochemical workstation and a Shimadzu UV1800 UV-visible spectrophotometer. The test results are as follows: Figure 3 , 4 , as shown in Figure 5.

[0084] like Figure 3 As shown in the figure, the maximum absorption peaks of TTP, TEP and TPP in the neutral state (0.0V) are 535nm, 545nm and 540nm, all showing red; with the continuous increase of voltage, the original absorption peak gradually disappears, and shows the characteristics of double absorption in the visible light region (the trough of the absorption curve appears between 500 and 600nm), showing yellow-green; with the voltage reaching 1.0V, the absorption curves of the three films in the visible light region have no obvious absorption peaks, showing a high-transmittance state. PBP3P is double-absorbent in the neutral state (0.0V), showing a green color at this time. As the voltage continues to increase, its absorption in the visible light region gradually decreases; when the voltage reaches 1V, it shows a high-transmittance state.

[0085] like Figure 4 and Figure 5 As shown, the optical contrast and cycle stability of TTP, TEP, TPP and PBP3P films in the maximum absorption peak band were tested respectively. The results show that the optical contrast of TTP in the wavelength range of 535nm is 34.08%, the coloring time is 0.77s, and the fading time is 0.87s; the optical contrast of TEP in the wavelength range of 545nm is 40.27%, the coloring time is 0.90s, and the fading time is 0.64s; the optical contrast of TPP in the wavelength range of 540nm is 45.52%, the coloring time is 0.65s, and the fading time is 0.38s; after 3000 cycles under the step voltage of 0V and 0.9V, the optical contrast of the three materials can maintain 60.92%, 87.83% and 68.52% of the initial contrast. PBP3P appears green in the neutral state, and eventually presents a high-transmittance state as the applied voltage increases. The optical contrast in the 640nm wavelength range is 43.56%, the coloring time is 0.90s, and the fading time is 0.56s. After 3000 cycles under a step voltage of 0V and 1.0V, the optical contrast of the film can maintain 88.25% of the initial contrast.

[0086] 3. Chromaticity tests and photos of TTP, TEP, TPP and PBP3P Use the CM-3600d spectrophotometer to express the color coordinates in the CIE 1976 L*a*b* color space. Figure 6 and Figure 7 As shown, at 0 V, TTP, TEP and TPP are red, reddish brown and pink, respectively. As the voltage continues to increase, the three films all appear yellow-green and eventually show a high-transmittance state. At 0 V, PBP3P appears green, and as the voltage continues to increase, the films all show a high-transmittance state.

[0087] Example 7 Preparation of electrochromic device ITO glass covered with TTP, TEP and TPP thin films were used as working electrodes and ITO glass covered with PBP3P as counter electrodes, respectively. They were assembled into red-yellow-green-green switching electrochromic devices according to the traditional sandwich structure, which are called TTP-PBP3P, TEP-PBP3P and TPP-PBP3P.

[0088] 1. Electrochemical testing of TTP-PBP3P, TEP-PBP3P and TPP-PBP3P The electrochemical test was performed using a Chenhua 660 electrochemical workstation with the following parameter settings: CV mode, scan rate of 50 / 100 / 200 / 300 / 500 mv / s, scan range of -1.0 V and 1.0 V. Figure 8 As shown, TTP-PBP3P, TEP-PBP3P and TPP-PBP3P all have electrochemical responses within this scanning range, and their CV curves have quasi-reversible redox behaviors.

[0089] 2. Optical and electrochromic performance test of TTP-PBP3P, TEP-PBP3P and TPP-PBP3P The optical and electrochromic performance test was carried out by using Chenhua 660 electrochemical workstation and Shimadzu UV1800 UV-visible spectrophotometer. The test results are as follows: Fig. 9 , 10 , as shown in 11.

[0090] like Fig. 9 As shown, the maximum absorption peaks of TTP-PBP3P, TEP-PBP3P and TPP-PBP3P in the neutral state (-1.0V) are 535nm, 545nm and 540nm, respectively, all showing a red color; as the voltage continues to increase, the original absorption peak gradually disappears, and the absorption peak belonging to PBP3P gradually appears, thus showing a yellow-green color; as the voltage reaches 1.0V, the absorption curves of the three devices in the visible light region show double absorption, showing green.

[0091] like Fig.10 and Fig.11 As shown in the figure, the optical contrast and cyclic stability of TTP-PBP3P, TEP-PBP3P and TPP-PBP3P in the maximum absorption peak band were tested respectively. The results showed that the optical contrast of TTP-PBP3P, TEP-PBP3P and TPP-PBP3P in the wavelength range of 650nm were 17.59%, 16.07% and 21.13% respectively; the coloring time and fading time were 1.05s / 0.60s, 1.00s / 0.68s and 0.36s / 0.38s respectively. After 15,000 cycles of testing, TTP-PBP3P and TPP-PBP3P could maintain 132.4% and 90.11% of the original contrast respectively; after 5,000 cycles of testing, TEP-PBP3P could maintain 97.51% of the original contrast.

[0092] 3. The colorimetric tests and photos of TTP-PBP3P, TEP-PBP3P and TPP-PBP3P use the CM-3600d spectrophotometer to express the color coordinates in the CIE 1976 L*a*b* color space. Fig.12 and 13 As shown, at -1.0 V, TTP-PBP3P and TPP-PBP3P appear red, reddish brown, and magenta, respectively. As the voltage increases, TTP-PBP3P and TPP-PBP3P appear green, while TEP-PBP3P appears yellow-green.

[0093] Example 8 Preparation of an electrochromic device with a nylon filter membrane added to the electrolyte layer ITO glass covered with TTP, TEP and TPP thin films were used as working electrodes and ITO glass covered with PBP3P as counter electrodes, respectively, in a sandwich structure. During the assembly process, nylon filter membranes with pore sizes of 10μm / 50μm / 100μm / 200μm were added to the electrolyte to assemble electrochromic devices containing nylon filter membranes with different pore sizes.

[0094] The transmission test was conducted by using Chenhua 660 electrochemical workstation and Shimadzu UV1800 UV-visible spectrophotometer. The test results are as follows: Fig.14 As shown in the figure, the three electrochromic devices containing nylon filters with different pore sizes have obvious gradient differences in transmittance in the neutral state (-1.0V) and the oxidized state (1.0V). Specifically, the smaller the pore size, the smaller the overall transmittance of the electrochromic device, and the smaller the difference in transmittance between the neutral state and the oxidized state. Fig.15 The following are photos of three devices containing a nylon filter with a pore size of 50 μm in neutral and oxidized states. It can be seen that the area where the nylon filter is located has a darker color, which can enhance the camouflage effect.

[0095] Example 9 Preparation of high performance patterned electrochromic camouflage device 15 mg of TTP, TEP, TPP and PBP3P were added to 10 ml sample bottles respectively, and 1 ml of chloroform was added thereto respectively. The solution was shaken to mix evenly, and then filtered using a microporous filter with a pore size of 0.45 μm. TTP, TEP and TPP were sprayed into different patterns on the conductive surface of 25*40 mm ITO glass or ITO-PET conductive film using a spray gun and a hollow mask (a metal plate that can penetrate the solution) respectively as working electrodes. Then, PBP3P was sprayed into a pattern on the conductive surface of 25*40 mm ITO glass or ITO-PET conductive film using a spray gun and a hollow mask (a metal plate that can penetrate the solution) as a counter electrode. Then, according to the sandwich structure, a nylon filter membrane with a pore size of 50 μm was added to the electrolyte during the assembly process to assemble a high-performance electrochromic camouflage device.

[0096] like Fig.16 As shown in the figure, due to the different oxidation voltages and intermediate colors of TTP, TEP and TPP, the patterned electrochromic camouflage device can switch between multiple camouflage modes after applying different voltages, and flexible devices can be prepared by replacing the conductive substrate. At the same time, since TTP, TEP, TPP and PBP3P are solution-processable electrochromic materials, large-sized camouflage devices can be prepared by spraying.

[0097] The above examples are for the purpose of illustrating the embodiments disclosed by the present invention and are not to be construed as limitations of the present invention. In addition, the various modifications listed herein and the variations of methods and compositions in the invention are obvious to those skilled in the art without departing from the scope and spirit of the present invention. Although the present invention has been specifically described in conjunction with various specific preferred embodiments of the present invention, it should be understood that the present invention should not be limited to these specific embodiments. In fact, various modifications obvious to those skilled in the art as described above to obtain the invention should be included within the scope of the present invention.

Claims

1. An electrochromic material, characterized in that: Its structural formula is as follows: Wherein: AR1 is a group represented by R1 or R3; AR2 is a group represented by R2 or R6; AR3 is selected from any one of R3, R4 and R5; AR4 is the group represented by R2; n is the degree of polymerization, n is 4 to 35; The structural formula of the groups represented by R1, R2, R3, R4, R5 and R6 is as follows:

2. The electrochromic material according to claim 1, characterized in that: AR1 is the group represented by R1, AR2 is the group represented by R2, AR3 is the group represented by R5, x, y, z and w are all 1; the structural formula of the electrochromic material is shown in Formula I:

3. The electrochromic material according to claim 1, characterized in that: AR1 is the group represented by R1, AR2 is the group represented by R2, AR3 is the group represented by R4, x, y, z and w are all 1; the structural formula of the electrochromic material is shown in Formula II:

4. The electrochromic material according to claim 1, characterized in that: AR1 is the group represented by R1, AR2 is the group represented by R2, AR3 is the group represented by R3, x, y, z and w are all 1; the structural formula of the electrochromic material is shown in Formula III:

5. The electrochromic material according to claim 1, characterized in that: AR1 is a group represented by R3, AR2 is a group represented by R6, AR3 is a group represented by R3, x, y and z are all 1, and w is 3; the structural formula of the electrochromic material is shown in Formula IV:

6. A method for preparing an electrochromic material as claimed in claim 2, characterized in that: Using N,N-bis(4-bromophenyl)-4-butylaniline as shown in formula V, 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene as shown in formula VI and 2,5-dibromothiophene as shown in formula VII as raw materials, reacting at 110-135° C. under a protective atmosphere to produce an electrochromic material as shown in formula I; 7. A method for preparing an electrochromic material as claimed in claim 3, characterized in that: Using N,N-bis(4-bromophenyl)-4-butylaniline as shown in formula V, 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene as shown in formula VI and 2,5-dibromo-3,4-vinyldioxythiophene as shown in formula VIII as raw materials, reacting at 110-135° C. under a protective atmosphere to produce an electrochromic material as shown in formula II; 8. A method for preparing an electrochromic material as claimed in claim 4, characterized in that: Using N,N-bis(4-bromophenyl)-4-butylaniline as shown in formula V, 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thieno[3,4-b][1,4]dioxepene as shown in formula VI and 6,8-dibromo-3,4-dihydro-3,3-dimethyl 2H-thieno[3,4-b][1,4]dioxepene as shown in formula IX as raw materials, reacting at 110-135° C. under a protective atmosphere to produce an electrochromic material as shown in formula III; 9. A method for preparing an electrochromic material as claimed in claim 5, characterized in that: The electrochromic material shown in Formula IV is prepared by reacting 4,7-bis(3,3-dimethyl-3,4-dihydro-2H-thienyl[3,4-b][1,4]dioxepin-6-yl)benzo[c][1,2,5]thiazole shown in Formula X, 3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thienyl[3,4-b][1,4]dioxepin shown in Formula VI and 6,8-dibromo-3,3-bis(((2-ethylhexyl)oxy)methyl)-3,4-dihydro-2H-thienyl[3,4-b][1,4]dioxepin shown in Formula XII; 10. Use of the electrochromic material according to claim 1 in preparing an electrochromic device.

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