KR100965225B1 - Electrochromic viologens with asymmetric structure and device therefrom - Google Patents

Abstract

The present invention relates to a novel asymmetric type viologen derivative capable of realizing a variety of colors when electrochromic and showing a fast response speed and an electrochromic device comprising the same. The electrochromic viologen derivative of the present invention is a compound having an alkyl group or an alkylene group having a terminal at the end of 4,4'-bipyridyl as a functional group, having the structure of Formula 1, easy to synthesize, simple and electrochromic device When it is applied to the voltage has the advantage of showing a quick response speed and high color contrast.

Electrochromic, Asymmetrical, Viologen, Electrochromic Device

Description

Preparation method of a novel asymmetric electrochromic viologen derivative and electrochromic device comprising the same {Electrochromic viologens with asymmetric structure and device therefrom}

The present invention relates to a novel viologen derivative having electrochromic properties and the characteristics of an electrochromic device to which the viologen derivative is applied. The electrochromic viologen derivatives of the present invention are easy and simple to synthesize, and when electrochromic devices are used, they show an improved response speed and higher color contrast than conventional viologen derivatives when voltage is applied.

Electrochromic reversibly adjusts the color of a material in response to the potential of an applied electric field, which can lead to a change in energy absorption due to electron transfer accompanying oxidation or reduction. Electrochromic materials include oxides of metals such as tungsten, iridium, nickel and vanadium, organic materials such as viologen and quinone, and conductive polymers such as polythiophene and polyaniline. Among them, viologen has been studied a lot since the 1970s because it can be easily and inexpensively synthesized. However, new electrochromic viologen is difficult due to the disadvantages of multi-color realization, inferior stability and memory effect, and slow response. Derivative development is stale.

Early electrochromic devices made by dissolving viologens with short alkyl chains such as methyl viologen in liquid electrolyte are very soluble in both 2+ (dication) and 1+ (radicalcation) forms of viologen. When the contrast of the coloration / discoloration or the applied voltage after removal is removed, the memory effect of maintaining color is inferior. In order to solve this phenomenon, methyl viologen is immobilized using metal oxide nanoparticles or the like on the surface of the electrode [US Patent 5441827, Graetzel et al] or methyl viologen is introduced by introducing a gel or a solid electrolyte instead of a liquid electrolyte. Cationic radicals have been used to slow the diffusion phenomenon from the electrode toward the bulk electrolyte. [Chem. Soc. Rev., 1997, 26 147]

However, it is easy to manufacture the electrochromic device having the memory effect, high color contrast, fast response and high stability only by the characteristics of the electrochromic material itself. Thus, studies have been made to develop 4,4'-bipyridine derivatives with long alkyl chains or complex aromatics to keep the cation radicals in the colored state by attaching them to the side [PCT Patent WO 2001/88060 (Horst Bernnet et al. ),], [Korea Patent Publication No. 10-2005-0063736] The viologen derivatives are not easily obtained by simple synthesis. In order to solve this problem, the inventors have invented a novel asymmetric viologen derivative synthesized by attaching alkyl or alkylene halide to only one side of the basic 4,4'-bipyridine unit. Was found to be stable for a long time and had high color contrast.

While the present inventors have studied electrochromic viologen derivatives, in the case of novel viologen derivatives having an asymmetric alkyl or alkylene group terminally terminated at 4,4'-bipyridyl units, the synthesis is simple and the applied voltage According to the present invention, the color intensity (intensity) can be finely adjusted, and the fast discoloration and color fading and the memory effect persist on the liquid electrolyte have been found to complete the present invention.

Accordingly, an object of the present invention is to provide a method for preparing a novel asymmetric viologen derivative compound and an electrochromic device to which the compound is applied.

The present invention provides an electrochromic material comprising a viologen compound in which an alkyl group or an alkylene group having a terminal terminal halogen asymmetrically connected to 4,4′-bipyridyl is connected.

Furthermore, an electrochromic device including the electrochromic material is provided.

First, the present invention provides a compound represented by the following formula.

And wherein R ¹ is an alkyl group or alkylene group of a carbon number of 2 ~ 20, X is Br, a halogen element such as Cl, Y ^- is a counter ion (counterion) of the Gen to rain Br ^- or I ^-, BF ₄ ^{- _{, Cl -, PF 6 -,}} ClO 4 -, SO 2 CF 3 -, N (SO 2 CF 3) 2 - are possible.

Examples of the formula (1) include the following compounds.

The present invention includes a solution type electrochromic device including the electrochromic material. The electrochromic device of the present invention is disposed on a transparent or reflective substrate and includes a working electrode, a counter electrode, and an electrolyte, and at least one of the working electrode, counter electrode, and electrolyte includes the electrochromic material of the present invention. . As the ion conductive electrolyte solution, a solution in which an electrolyte salt is dissolved may be used, and the electrochromic material is dissolved and used for the preparation of the electrochromic device by a method such as injection or vacuum entry.

At this time, the electrochromic electrolyte mixed solution is 1) 0.0005 ~ 10 M electrochromic compound represented by Formula 1; 2) 0.001 to 10 M of electrolyte salt, preferably 0.1 to 0.5 M; And 3) 1 M of solvent.

If the amount of the viologen derivative is less than 0.0005 M, the electrochromic property is not observed. If the amount of the viologen derivative is greater than 10 M, the compound may be eluted from the solution.

In this case, the electrolyte salt is a general one used in the art, but is not particularly limited, and specifically n-Bu ₄ NClO ₄ , n-Bu ₄ NPF ₆ , NaBF ₄ , LiClO ₄ , LiPF ₆ , LiBF ₄ , LiN (SO ₂ C ₂ F ₅ ) ₂ , LiCF ₃ SO ₃ , C ₂ F ₆ LiNO ₄ S _{2 ,} K ₄ Fe (CN) ₆ and the like can be used. These electrolyte salts can use 1 type of single compound or 2 or more types of mixtures. Since the electrolyte salt is used in the range of 0.001 to 10 M, it is preferable to maintain the above range because the amount of the electrolyte salt is less than 0.001 M, the electrochromic property is not observed, and when the amount exceeds 10 M, the compound is eluted from the solution. .

In this case, when the electrochromic device is manufactured, a compound having additional electrochromic properties, specifically, methyl viologen, dimethyl viologen, dimethyl viologen, diisobutyl viologen, and benzyl viol Single compound or two or more selected from benzyl viologen, 1-benzyl viologen, 1,1′-dibenzyl viologen, and derivatives thereof The mixture may be mixed and used, and may be contained in an amount ranging from 0.001 to 700 parts by weight based on 100 parts by weight of the novel viologen derivative. The solvent is a non-aqueous solvent used in the art, specifically one selected from dichloromethane, chloroform, acetonitrile, ethylene carbonate (EC), propylene carbonate (PC), tetrahydrofuran (THF), butylene carbonate, and the like. The above solvent can be used.

In addition, it may contain antioxidants such as AO-30, AO-60, IRGANOX 1010, DH-43, and the like, which are commonly used in the art, and such additives may be used by those skilled in the art. Can be.

The electrochromic device may be used for a large-area information display device, a small-area portable information display device, a car window for blocking sunlight, a building window, and the like.

As described above, the novel asymmetric viologen derivative synthesized according to the present invention is easy and simple to synthesize, and when applied to an electrochromic device, has a very fast color response and different color upon color depending on the electrolyte salt. It is possible to have excellent memory characteristics in liquid electrolyte, and it is possible to save electricity and have excellent electrochromic characteristics.

Such electrochromic materials are easily used in the construction of electrochromic devices, and the electrochromic devices manufactured therefrom are widely used in various fields such as displays, e-books, electronic papers, rearview mirrors, portable computers, solar control windows, and decorative products. It is possible.

Hereinafter, the present invention will be described in detail with reference to the following examples. The following examples are only for explaining the present invention in detail, and the present invention is not limited thereto.

Starting materials for the compounds 1-1 to 10 are known from the literature (Macromol. Rap. Commun. 2007, 28 101; Polym. Adv. Tech. 1999, 10 60; Helvetica Chim. Act. 2000, 83, 181; Tetrahedron Lett 1994, 35 4835; Polymer 2001, 42 807; Nanotechnology 2006, 17 403).

[ Example  One]

* Preparation of Compound 1-1

4,4'-bipyridinium bromide (0.1 g, 0.42 mmol) was added to a solution of N, N-dimethylformamide (DMF, 5 ml) / CH ₃ CN (25 ml) in dibromohexane (0.25 g, 1.02 mmol). Was refluxed at 120 ° C. for 48 h. After the reaction, the precipitate was washed several times with CH ₃ CN and dried under reduced pressure to obtain a compound in an orange solid state. (Yield 76%; see Formula 2 below)

¹ H NMR (300 MHz, D ₂ O; δ), δ = 1.3 (2H), 1.28 (2H), 1.79 (1H), 3.3 (1H), 7.6 (2H), 8.67 (2H), 8.7 (2H) , 9.27 (2H)

MS (70 eV, EI): 319.5 m / z

[ Example  2 ~ 5]

* Preparation of Compounds 1-2 to 1-5

The same procedure as in Example 1 was carried out, but the compound 1-2 to 1-5 was obtained by changing the conditions as described in Table 1 below.

Example 6

Preparation of Compound 1-6

(Dichlorobenzyl) octadecyldimethylammonium chloride was synthesized by applying a known method (Nanotechnology, 2006, 17 403), and 1-6 was synthesized by the method of Example 1. (Yield 52%)

¹ H NMR (300 MHz, D ₂ O; δ), δ = 9.3 (2H), 8.7 (2H), 8.67 (2H), 7.6 (2H), 6.94 (4H), 4.5 (1H), 3.38 (1H) , 3.24 (1H), 1.73 (1H), 1.57 (1H), 1.29 (13H)

MS (70 eV, EI): 578.5 m / z

EXAMPLES 7-10

* Preparation of Compounds 1-7 to 1-10

The same procedure as in Example 6 was repeated except that the compound 1-7 to 1-10 were obtained under the same conditions as shown in Table 1 below.

[ Example  11-23]

* Electrochromic device fabrication using compounds 1-1 to 1-10

The viologen compound obtained according to the above examples was mixed with an electrolyte salt and an organic solvent as shown in Table 2 with a spacer having a thickness of 20 μm between two sheets of ITO glass as an electrode, injected and sealed, and then electrochromic. The device was manufactured. The manufactured electrochromic device was discolored blue or red after at least 20 msec when a minimum 1.25 V voltage was applied.

[ Experimental Example : Electrochromic Experiment of Electrochromic Device]

When the applied voltage is changed from 0 V to -2.0 V or 2.0 V in the fabricated electrochromic device, the color changes from colorless transparent to dark blue. The response time was measured as the time taken to change 70% of the total absorbance change at 590 nm while changing the applied voltage from -2.0 V to 2.0 V every 30 seconds. At this time, the color contrast (ΔOD, optical density) is calculated by Equation 1.

Color Contrast (ΔOD) = log [Transmittance (%) / Coloration (%)]

The coloring duration is defined as the time taken for 90% of the absorbance to decrease after removing the applied voltage after coloring.

In addition, the coloration efficiency (CE) of the electrochromic device can be obtained, and it is calculated by Equation 2.

Discoloration efficiency (CE, cm ² / C) = color contrast (ΔOD) / charge consumption per unit area (C / cm ² )

1A is a photograph of a discolored / colored state of an eleventh electrochromic device.

1B is a photograph of a discolored / colored state of the Example 12 electrochromic device.

Claims (5)

Next, a viologen compound-based electrochromic material represented by Chemical Formula 1.

(Where, in formula 1, R ¹ is an alkyl group or alkylene group of a carbon number of 2 ~ 20, X is a halogen element such as Br, Cl, Y ^- as a counter ion of Gen in the rain Br ^-, BF ₄ ^{-, _{Cl -, PF 6 -, ClO}} 4 - and _{^{a) -, SO 2 CF 3 -}} , N (SO 2 CF 3) 2. The electrochromic material of claim 1, wherein R ¹ comprises an aromatic cyclic compound. The electrochromic material of claim 1, wherein the viologen compound comprises a counterion, and the counterion is Br ⁻ , I ⁻ , BF ₄ ⁻ , Cl ⁻ , PF ₆ ⁻ . The electrochromic material of claim 1, wherein the viologen compound has a structure of Formulas 1-1 to 1-10.

Electrochromic device comprising a viologen compound-based electrochromic material of claim 1.

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