KR101914393B1 - High performance electrochromic chromophores, application to electrochromic devices, and their operation method - Google Patents

Abstract

The present invention relates to an electrochromic compound which is represented by chemical formula 1. The present invention further relates to an electrochromic device including the same, and an operation method thereof. According to the present invention, it is possible to provide an electrochromic device with improved coloring efficiency, coloring-bleaching reaction rate, and coloring-bleaching operation stability. In the chemical formula 1, Ar^1, Ar^2, R^1, R^2, A^-, n^1, and n^2 are the same as described in the specification.

Description

TECHNICAL FIELD [0001] The present invention relates to a high-performance electrochromic compound, an electrochromic device including the electrochromic device, and a driving method thereof. BACKGROUND OF THE INVENTION [0001]

The present invention relates to an electrochromic compound having improved coloring efficiency, coloring-bleaching reaction rate and coloring-bleaching operation stability, an electrochromic device comprising the same, and a driving method thereof.

Electrochromism is a phenomenon that reversibly changes color when electrochemically oxidizing or reducing the electrode material. A device made of an organic or inorganic electrochromic material can be manufactured as a wide area device at a low cost even though the response speed is slower than that of a conventional cathode ray tube (CRT), a liquid crystal display (LCD), or a light emitting diode (LED) Because it has low power consumption, it can be applied to many fields such as smart window, smart mirror, and electronic paper.

In addition, the development of smart windows / films using electrochromic materials can reduce the emission of fossil fuel emissions through alternative energy utilization, save energy, and contribute to environmental conservation. Therefore, The development of a new concept window that can control the active function such as the effect and the heat transmission can improve the quality of life by improving the residential culture and office environment.

It is an object of the present invention to provide electrochromic compounds having improved properties.

Another object of the present invention is to provide an electrochromic device comprising the electrochromic compound having improved coloring efficiency, coloring-bleaching reaction rate and coloring-bleaching operation stability.

It is still another object of the present invention to provide a method of driving the electrochromic device.

The present invention provides an electrochromic compound represented by the following formula (1).

[Chemical Formula 1]

Wherein Ar ¹ and Ar ² are each independently an aryl group represented by the following formula (2), R ¹ and R ² each independently represents a halogen group, a nitryl group, a nitro group, an amino group, an alkyl group, an alkoxy group, A halogenated alkyl group and a heteroaryl group, A ^- is an anion, and n ¹ and n ² are each independently an integer of 0 to 4.

(2)

In Formula 2, R ³ is a halogen group, and n ³ is an integer of 0 to 4.

In Formula 2, n ³ is an integer of 1 to 4, and R ³ may be any halogen group selected from the group consisting of F, Cl, Br and I.

The electrochromic compound may be an electrochromic compound represented by the following formula (3).

(3)

In Formula 3, A ^- is an anion.

The anion may be any one selected from the group consisting of TFSI ^- (bis (trifluoromethylsulfonyl) imide), PF ₆ ^- , BF ₄ ^-, and combinations thereof.

The present invention also relates to a plasma display panel comprising a pair of electrodes; And an electrochromic layer disposed between the pair of electrodes, wherein the electrochromic layer comprises an ion gel and an electrochromic compound represented by the formula (1).

The ionic gel may comprise a polymer matrix and an ionic salt in a liquid state at room temperature.

The polymer matrix may be any one of poly (vinylidene fluoride) and poly (styrene); And any one polymer selected from the group consisting of poly (hexafluoropropylene), poly (ethylene oxide), poly (alkyl methacrylate), and poly (alkyl acrylate).

The ionic salt in the liquid state at room temperature is preferably 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, [EMI] [TFSI] ), 1-ethyl-3-methylimidazolium hexafluorophosphate, [EMI] [PF ₆ ]), 1-ethyl-3-methylimidazolium tetrafluoroborate 1-ethyl-3-methylimidazolium tetrafluoroborate, [EMI] [BF ₄ ], 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) 1-butyl-3-methylimidazolium hexafluorophosphate, [BMI] [PF ₆ ]), 1-butyl-3-methylimidazolium hexafluorophosphate (1-butyl-3-methylimidazolium tetrafluoroborate, [BMI] [BF ₄ ]), and combinations thereof. have.

The present invention also relates to a plasma display panel comprising a pair of electrodes; And an electrochromic layer disposed between the pair of electrodes, wherein the electrochromic layer comprises an ion gel and an electrochromic compound represented by Formula 1, An ON step of supplying an electric current for a period of time; And an OFF step of shutting off current for a predetermined time, the ON step; And an off (OFF) step are performed at an intersection.

The present invention can provide electrochromic compounds with improved properties.

The present invention can also provide an electrochromic device comprising the above electrochromic compound having improved coloring efficiency, coloring-bleaching reaction rate and staining-bleaching operation stability.

The present invention can also provide a method of driving the electrochromic device.

1 is a schematic view showing the constituent elements and the chemical structure of the electrochromic device manufactured in Production Example 2 of the present invention.
2 shows UV-vis absorption spectra at various voltages in the electrochromic device according to Reference Example 1 of the present invention.
3 shows UV-vis absorption spectra at various voltages in the electrochromic device according to Example 1 of the present invention.
4 shows UV-vis absorption spectra at various voltages in the electrochromic device according to Example 2 of the present invention.
5 is a graph showing the color coordinates analyzed in Experimental Example 1 of the present invention.
6 is a result of recording an instantaneous transmittance profile at 596 nm in order to evaluate the color change rate of the electrochromic device according to Reference Example 1 of the present invention.
7 shows the result of recording the instantaneous transmittance profile at 596 nm in order to evaluate the coloring speed of the electrochromic device according to Example 1 of the present invention.
8 is a graph showing a plotted value of injected charge quantity density versus optical density at -0.00 V and -0.23 V of the electrochromic device according to Reference Example 1 of the present invention.
9 is a graph showing a plotted value of the injected charge density versus optical density at -0.00 V and -0.35 V of the electrochromic device according to Example 1 of the present invention.
10 is a graph showing a change in the normalized transmittance of the electrochromic device according to an experimental example of the present invention. Reference Example 1 for black, and Example 1 for red.
11 is cyclic voltammograms of an electrochromic device according to Reference Example 1 of the present invention.
12 is cyclic voltammograms of the electrochromic device according to Example 1 of the present invention.
13 is cyclic voltammograms of an electrochromic device according to Example 2 of the present invention.

Hereinafter, the present invention will be described in detail.

Unless otherwise stated, alkyl groups include primary alkyl groups, secondary alkyl groups, and tertiary alkyl groups.

Unless otherwise specified in the specification, the halogen group means a fluoro group, a chloro group, a bromo group or an iodo group.

In the present specification, unless otherwise specified, all the compounds or substituents may be substituted or unsubstituted. The term "substituted" as used herein means that hydrogen is substituted with at least one substituent selected from the group consisting of a halogen group, a hydroxyl group, a carboxyl group, a cyano group, a nitro group, an amino group, a thio group, a methylthio group, an alkoxy group, a nitryl group, an aldehyde group, Means a substituted one selected from the group consisting of an acetal group, a ketone group, an alkyl group, a perfluoroalkyl group, a cycloalkyl group, a heterocycloalkyl group, a benzyl group, an aryl group, a heteroaryl group, a derivative thereof and a combination thereof .

Unless otherwise specified in the present specification, the alkyl group is a linear or branched alkyl group having 1 to 10 carbon atoms, a halogenated alkyl group is a linear or branched halogenated alkyl group having 1 to 10 carbon atoms, an aryl group is an aryl group having 6 to 30 carbon atoms, A heteroaryl group having 2 to 30 carbon atoms, and an alkoxy group means an alkoxy group having 1 to 10 carbon atoms.

Unless otherwise specified herein, a halogenated alkyl group means an alkyl group in which some hydrogen atoms or all of the hydrogen atoms are replaced with halogen atoms. For example, the halogenated alkyl group may include a perfluoroalkyl group.

Unless otherwise specified in the specification, an aryl group means a chemical group obtained by removing one hydrogen atom from a monocyclic or polycyclic compound having 2 to 30 carbon atoms including at least one benzene ring and derivatives thereof, Examples of the monocyclic or polycyclic compound containing a benzene ring include a benzene ring, biphenyl in which two or more benzene rings are bound by a single bond, such as toluene or xylene having an alkyl side chain attached to a benzene ring, etc., a benzene ring is a cycloalkyl group or a heterocyclo Naphthalene or anthracene condensed with two or more benzene rings such as fluorene, xanthene or anthraquinone condensed with an alkyl group, and the like.

Unless otherwise specified herein, the prefixed heteroaryl means that one to three heteroatoms selected from the group consisting of -N-, -O-, -S-, and -P- substitute carbon atoms. For example, pyridine, pyrrole or carbazole containing a nitrogen atom as a hetero atom, furan or dibenzofuran containing an oxygen atom as a hetero atom, or dibenzothiophene, diphenylamine, and the like.

Unless otherwise specified in the present specification, an asterisk (*) in the formula represents a moiety wherein this compound is substituted by another compound.

As used herein, the combination thereof means that two or more substituents are bonded to each other through a single bond or a linking group, or two or more substituents are condensed and connected unless otherwise specified.

An embodiment of the present invention provides an electrochromic compound represented by the following formula (1).

[Chemical Formula 1]

In Formula 1, R ¹ and R ² are each independently any one selected from a halogen group, a nitro group, a nitro group, an amino group, an alkyl group, alkoxy group, aryl group, halogenated alkyl group and a heteroaryl group the group consisting of, n ¹ To n < ² > are each independently an integer of 0 to 4;

In Formula 1, Ar ¹ and Ar ² may each independently be an aryl group represented by Formula 2 below.

(2)

In Formula 2, R ³ is a halogen group, and may be any one of halogen groups selected from the group consisting of F, Cl, Br and I, and more specifically, F. N ³ is an integer of 0 to 4, specifically, an integer of 1 to 4, more specifically 1.

In the above formula (1), A ^- represents an anion. Specifically, for example, A ^- may be a halogen anion such as F ^- , Cl ^- , Br ^- or I ^- or a combination of TFSI ^- (bis (trifluoromethylsulfonyl) imide), PF ₆ ^- , BF ₄ ^- And an anion selected from the group consisting of

The molecular weight of the anion may be 145 to 280 g / mol. Specifically, the molecular weight of the TFSI is 280 g / mol and the molecular weight of PF ₆ is 145 g / mol. This is because the size of the anion component is controlled so that the electrochromic material easily fuses in the ion gel. This may be selected depending on the type of ion gel used, and is not particularly limited in the present invention.

The electrochromic compound means a compound which is discolored into a color differentiated by different applied voltages. The electrochromic compound includes a cation component and an anion component including a phenyl group functionalized at both terminals centered on a viologen structure. The electrochromic compound induces a green colored state when the viologen is in a reduced (+) state, and a bleached (off-white) state when it is in an oxidized (2+) state.

The electrochromic compound can be obtained from a synthesis process involving the Zincke reaction, including the functionalized phenyl substituent, to obtain a more stable and high purity green color with a lower a * value of the CIELAB color coordinate system.

The electrochromic compound is characterized in that the substituent at both terminals is a phenyl group substituted with CF ₃ group. The electrochromic compound contains a phenyl group substituted with the CF ₃ group, so that the electrochromic compound has an effect of showing green in a hydrophobic electrolyte. Accordingly, the electrochromic compound may have a color purity of L * = 50 to 62, a * = -25 to -35 and b * = 20 to 30, more specifically, a color purity of L * = 51 to 52, a * = -34 to -35, and b * = 29 to 30.

In addition, the electrochromic compound may further include any one halogen group selected from the group consisting of F, Cl, Br, and I in which the phenyl group substituted with the CF ₃ group is included. When the phenyl group substituted with the CF ₃ group contains the halogen group, the color purity is higher and the device stability is improved. Specifically, the electrochromic device including the electrochromic compound improves the reversibility of the oxidation-reduction reaction, thereby improving the device driving stability. When used in an ion gel, the electrochromic reaction stability and the implementation of a green pixel with high color purity Not only is it possible, but also device implementations that are flexible or stretchable are possible, so that better effects can be obtained.

In addition, since the phenyl group substituted with the CF ₃ group further includes the halogen group, the affinity of the halogen anion or anion such as TFSI ^- , PF ₆ ^- or BF ₄ ^- can be increased, Solubility is improved.

Specifically, the electrochromic compound may be represented by the following formula (3).

(3)

In the above formula (3), A ^- represents an anion.

In another embodiment of the present invention, a pair of electrodes; And an electrochromic layer disposed between the pair of electrodes, wherein the electrochromic layer comprises an ion gel and an electrochromic compound represented by the formula (1). The definition of the electrochromic compound is the same as that of the embodiment of the present invention described above.

The electrochromic compound means a compound which is discolored into a color differentiated by different applied voltages. By using such a device, it is possible to control the applied voltage and adjust the color of the discoloration of the device.

More specifically, the electrochromic layer includes an ion gel and a plurality of electrochromic compounds, wherein the ion gel is an electrolyte matrix, and the electrochromic compound in the ion gel is uniformly dissolved.

The ion gel includes a heterogeneous polymer copolymer. The heterogeneous polymer copolymer may be any one of poly (vinylidene fluoride) and poly (styrene), which is capable of improving the mechanical strength of the ion gel by not mixing with an ionic liquid; Poly (ethylene oxide), poly (alkylmethacrylate), and poly (alkylmethacrylate), which are mixed with the ionic liquid and act as a part of the ion gel where an electrochemical reaction can take place, Alkyl acrylate), and the like.

The ionic gel may further include an ionic liquid, that is, an ionic liquid, which is in a liquid state at room temperature. The ionic salt in the liquid state at room temperature is preferably 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, [EMI] [TFSI] ), 1-ethyl-3-methylimidazolium hexafluorophosphate, [EMI] [PF ₆ ]), 1-ethyl-3-methylimidazolium tetrafluoroborate 1-ethyl-3-methylimidazolium tetrafluoroborate, [EMI] [BF ₄ ], 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) 1-butyl-3-methylimidazolium hexafluorophosphate, [BMI] [PF ₆ ]), 1-butyl-3-methylimidazolium hexafluorophosphate (1-butyl-3-methylimidazolium tetrafluoroborate, [BMI] [BF ₄ ]), and combinations thereof. have.

Such an ionic salt is a substance that can help the movement of ions in the electrolyte, and can be effectively applied to an ionic gel in a liquid state at room temperature. The ionic salt in a liquid state at room temperature may preferably have 1 to 10 carbon atoms in the ionic salt. The ionic salts listed above exhibit an increase in viscosity as the number of carbon atoms in the ionic salt increases, but they remain liquid even when the number of carbon atoms is less than 10 (decyl).

The electrochromic layer may further include an anode redox compound. The anode redox compound may be any one selected from the group consisting of dimethyl ferrocene (dmFc), ferrocene (Fc), hydroquinone, potassium ferrocyanide, and combinations thereof. have.

The electrochromic device may be flexible or stretchable. For this purpose, the substrate itself may be a plastic substrate or a flexible material. Specific examples of the plastic that can be used include transparent plastic such as polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyethersulfone, polyimide, glass fiber reinforced plastics and the like. However, when the product is not required to have a flexible characteristic, the substrate may be made of glass.

The pair of electrodes includes an inorganic or organic conductive material, and may be transparent. For example, an inorganic material such as indium tin oxide (ITO), indium zinc oxide (IZO), and florine-doped tin oxide (FTO), and organic materials such as polythiophene and phenyl polyacetylene .

In another embodiment of the present invention, a pair of electrodes; And an electrochromic layer positioned between the pair of electrodes, wherein the electrochromic layer comprises an ion gel and an electrochromic compound represented by the following general formula (1): An ON step of supplying an electric current for a period of time; And turning off the current for a predetermined period of time; The ON step; And an off (OFF) step are performed at an intersection. The definition of the electrochromic compound is the same as that of the embodiment of the present invention described above.

The predetermined time of the ON step may be 20 to 25 seconds, and the predetermined time of the OFF step may be 10 to 35 seconds. Through adjustment of the driving method, it is possible to adjust the time of power application, and finally, the device can be driven with low power.

As the electrochromic device includes the electrochromic compound, the electrochromic device may have a transmittance to light of a specific wavelength of 20% or less, specifically 15 to 18%. The maximum absorption wavelength upon discoloration may be from 590 nm to 600 nm.

Hereinafter, examples and comparative examples of the present invention will be described. However, the following examples are only illustrative of the present invention and are not intended to limit the scope of the present invention.

[ Manufacturing example  1: electrochromic compound]

All materials in this example were purchased from Sigma-Aldrich.

< Reference example  1>

An electrochromic compound represented by the following Chemical Formula 4 was prepared and used (hereinafter referred to as CNPhV ²⁺ ).

[Chemical Formula 4]

The synthesis route and the molecular structure of the compound of Reference Example 1 are shown in Scheme 1.

[Reaction Scheme 1]

Briefly, a mixture of 4,4'-bipyridine (32 mmol, 1 eq) and 2,4-dinitrochlorobenzene (128 mmol, 4 eq) dissolved in dry acetonitrile (80 mL) And the resulting yellow solution was cooled to room temperature and filtered. A bright yellow precipitate was obtained and washed with anhydrous acetonitrile.

The crude product was recrystallized from deionized water / acetone and vacuum dried for 24 hours to give a yellowish green product (1,1'-bis (2,4-dinitrophenyl) -4,4'-bipyridinium dichloride, DNPhVCl ₂ ) &Lt; / RTI &gt;

The DNPhVCl ₂ (1.78 mmol, 1 eq) was dissolved in 50% aqueous ethanol (40 mL) and an ethanol solution (10 mL) of 4-aminobenzonitrile (10.68 mmol, 6 eq) was added dropwise. After refluxing for 72 hours, the solution was cooled to room temperature. The resulting red solution was evaporated with a rotary evaporator to remove excess ethanol.

Additional deionized water (200 mL) was introduced and stirred at room temperature for 1 hour. The solution was filtered and the filtrate was evaporated to give 1,1'-bis (2,4-cyanophenyl) -4,4'-bipyridinium dichloride, CNPhVCl ₂ .

For the anion exchange, an excess of lithium bis (trifluoromethanesulfonyl) imide ([Li] [TFSI]) solution in deionized water was reacted with an aqueous solution of CNPhVCl ₂ at room temperature for 20 minutes. The precipitated CNPhV (TFSI) ₂ was collected and dried in vacuum for 24 hours.

[EMI] [Cl] and excess [Li] in deionized water were obtained from ionic liquid 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide And [TFSI].

< Example  1>

(Hereinafter referred to as TFMFPhV ²⁺ ).

[Chemical Formula 5]

Except that generate TFMFPhVCl ₂ by introducing Ar 1 is Ar 2 in place of CNPh TFMFPh in Reference Example 1 instead of ₂ CNPhVCl as intermediates, which was prepared in the same manner as in the above method.

< Example  2>

An electrochromic compound represented by the following formula (6) was prepared and used (hereinafter referred to as TFMPhV ²⁺ ).

[Chemical Formula 6]

Except that generate TFMPhVCl ₂ by introducing Ar 1 is Ar 3 CNPh instead of TFMPh in Reference Example 1 instead of ₂ CNPhVCl as intermediates, which was prepared in the same manner as in the above method.

[ Manufacturing example  2: Manufacture of electrochromic device]

The electrochromic device was prepared so as to include a pair of ITO-coated glass as an electrode, and an electrochromic layer containing an electrolyte, an electrochromic compound and an anode redox compound between the pair of electrodes. A heteropolymeric polymer (PVDF-co-HFP) of poly (vinylidene fluoride) polymer and poly (hexafluoropropylene) polymer as an electrolyte; ([EMI] [TFSI]) was used as an ion-exchange resin and 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide The prepared electrochromic compound and dimethylferrocene (dmFc) were mixed in equimolar.

Electricity Discoloration layer  Produce

The electrochromic compound prepared in Preparation Example 1 and an anode redox compound (dmFc) (equimolar); Heteropolymer copolymer (PVDF-co-HFP); And an ionic salt ([EMI] [TFSI]) were mixed in a weight ratio of 3: 4: 36, and all of the above components were completely dissolved in acetone at 50 占 폚.

The prepared homogeneous solution was cast on a slide glass and dried in ambient air. Residual acetone was completely removed in vacuum.

Manufacture of electrochromic devices

The fabricated electrochromic layer was placed on a ITO coated glass (sheet resistance: 10 Ω / sq, Asahi Glass Co.) through a "cut-and-stick" method.

The electrochromic device was prepared by fixing the ITO coated glass on the electrochromic layer by using a double-sided tape having a thickness of 88 μm, and then placing another ITO-coated glass on the electrochromic layer.

A schematic diagram of the constituent elements and the chemical structure of the electrochromic device manufactured is shown in Fig.

[ Experimental Example  1: UV- vis  Change in absorption spectrum and color in bleached-colored state CIELAB  analysis]

In order to evaluate the voltage dependency of the optical characteristics of the electrochromic device prepared in Production Example 2, UV-vis absorption spectra were recorded at various voltages and the photographs of bleached and colored states were compared. The redox potentials of Reference Example 1 (CNPhV ^{2 +} ), Example 1 (TFMFPhV ^{2 +} ) and Example 2 (TFMPhV ²⁺ ) were calculated according to the redox potential of the internal standard dmFc ⁺ / dmFc. The change in UV-vis absorption spectrum of ECDs was measured from 400 to 850 nm using a UV-vis spectrometer (V-730, Jasco) at a scan rate of 400 nm / min. The applied DC voltage was supplied by a Sourcemeter (Keithley 2400, Tektronix).

CIELAB color coordinates of the colored and bleached electrochromic devices were estimated using Spectra Magic NX software (CM-S100w, Konica Minolta). The color coordinates are shown in Fig. L * represents the brightness of the color, a * and b * correspond to the position of the color, and a * represents from green (-) to red (+) and blue (-) to yellow (+), respectively. The lower the a * value, the higher the purity of the color.

The change in the UV-vis absorption spectrum of the electrochromic device containing the electrochromic compound of Reference Example 1 is shown graphically in Fig. The right side of the graph is a photograph of bleached and colored state at -0.0 V and -0.23 V, respectively.

2, absorption peaks were not observed at -0.13 V or less except for peaks of 450 nm or less generated from dmFc in the electrolyte (ion gel). As shown in the photograph at -0.0 V on the right side of Fig. 2, the electrochromic device before the coloring was slightly yellowed in the bleached state due to dmFc.

As the voltage increased, the device absorbed a broad range of wavelengths and exhibited characteristic peaks at 596 nm and 655 nm. As shown in the photograph at -0.23V on the right side of Fig. 2, the electrochromic device appeared green after the coloration occurred. The CIELAB coordinates (L *, a *, b *) at -0.23V were (54.7, -22.8, 18.8).

The UV-vis absorption spectrum of the electrochromic device comprising the electrochromic compound of Example 1 is shown in FIG. 3 as a graph. On the right side of the graph are photographs of bleached and colored states at -0.0 V and -0.35 V, respectively.

The bleaching state of Example 1 was the same as the bleaching state of Reference Example 1, while the coloration to green was started at a slightly higher voltage of -0.2 V than in the Reference Example.

However, the CIELAB coordinates (L *, a *, b *) at -0.35V showed (51.5, -34.1, 29.8) (Fig. 5). When estimating the color coordinates of the induced green, it was confirmed that a * was moved to a negative value remarkably. This means that a more pure green color is implemented.

The change in the UV-vis absorption spectrum of the electrochromic device comprising the electrochromic compound of Example 2 is shown graphically in Fig. Referring to FIG. 4, bleaching state was shown at -0.35 V or less, and the coloration to green started at -1.00 V, which was somewhat higher. CIELAB coordinates (L *, a *, b *) showed (61.13, -26.41, 21.84) (Fig. 5). It was confirmed that the a * value of Example 2 was lower than the a * value of Reference Example 1, but higher than the value of Example 1. When the electrochromic device was fabricated in an ion gel of the same condition, the a * higher value was obtained in Example 2 (TFMPhV ^{2 +} ) containing no halogen group than in Example 1 (TFMFPhV ²⁺ ) It was also confirmed by numerical analysis that the purity of bore green was lower.

To determine the type of operation of the device, the electrochromic device containing the electrochromic compound (TFMFPhV ^{2 +} ) of Example 1 was disassembled. As a result, a green gel with no residual solids was observed on the electrode.

(Type I ECD) electrochromic device comprising the electrochromic compound (TFMFPhV ^{2 +} ) of Example 1 based on the bleached species (TFMFPhV ^{2 +} ) and the colored species (TFMFPhV ⁺ .

[ Experimental Example  2: transmittance profile]

An instantaneous transmittance profile at 596 nm was recorded to evaluate the bleaching and coloring rate of the electrochromic device prepared according to Preparation Example 2 and shown in Figures 6 and 7. Transient and transmittance profiles were recorded using a combination of UV-vis spectroscopy and a potentiometer.

To understand the dynamics of the device of the electrochromic device comprising the electrochromic compound (CNPhV ^{2 +} ) of Reference Example 1, transient transmittance profiles at 596 nm corresponding to one of the characteristic peaks were recorded 6.

When the voltage of -0.23 V was applied, the transmittance of the electrochromic device gradually decreased and the coloring time defined as a time interval reaching 90% (? T90%) of the total transmittance change was 74 seconds. While the bleaching time was measured as ~ 398 seconds and ~ 122 seconds in open circuit and short circuit conditions, respectively. It was predictable to recover the transmittance three times faster in short circuit.

Only one passageway is possible in the open circuit condition to the uncolored state (chemical bleaching by reaction between CNPhV ^{2 +} , for example CNPhV ^{2 +} and dmFc ⁺ ). When the circuit is short-circuited, a relatively quick re-direct the CNPhV ^{+ ·} (or dmFc ⁺⁾ - and the oxidation occurs at the same time in the vicinity of the electrode.

As a result, faster bleaching behavior was obtained in short circuit conditions consistent with previously reported gel-based type 1 (Type IEDS) behavior.

The transient transmittance profiles at 596 nm of the electrochromic device containing the electrochromic compound (TFMFPhV ^{2 +} ) of Example 1 were recorded and shown in FIG.

The electrochromic device exhibited a faster response time of? T 10 sec (short circuit condition) and 32 sec (open circuit condition) for bleaching, and good reversibility of the coloring / bleaching cycle was observed at -0.35 V for tinting .

Transparency levels in the bleached state were almost recovered by open or short circuit conditions. This high transmittance change (DELTA T = 73%) can be advantageously compared with other green-colored electrochromic devices based on viologens.

[ Experimental Example  3: Coloring efficiency (侶, ΔOD / Q)]

Changes in optical density (? OD) per injected charge density (Q) were measured and shown in Figs. 8 and 9. ΔOD / Q) defined by a change in the optical density (ΔOD) per charge density (Q) injected from the graph can be derived.

The coloring efficiency η value for the electrochromic device including the electrochromic compound (CNPhV ^{2 +} ) of Reference Example 1 shown in FIG. 8 was measured at -73.22 cm 2 / C at -0.23 V. This is comparable to the efficiency of a previously reported viologen-based type I electrochromic device.

The? Value for the electrochromic device including the electrochromic compound (TFMFPhV ^{2 +} ) of Example 1 shown in FIG. 9 was 79.39 cm 2 / C at -0.35 V. It lies in the η range of the analogue virologen system.

Although the coloring voltage of Example 1 was slightly higher, it was found that Example 1 (TFMFPhV ^{2 +} ) required a smaller amount of charge for coloration of a particular region.

[ Experimental Example  4: transmittance ( ΔT )]

The change in the normalized transmittance (? T) over time is plotted and shown in FIG. 10 to see the persistence of the coloration of the electrochromic device and the degree of performance degradation after the coloring-bleaching cycle. Reference Example 1 for black, and Example 1 for red.

In the case of the electrochromic device including Reference Example 1, an extreme decrease (72%) of the initial value? To in the initial stage (? 1 h) was observed, and then? T was further decreased to 0.06.

On the other hand, in the case of the electrochromic device including Example 1, only a 14% reduction in the initial value (? To) occurred in the initial stage (~ 1 h). After 25 hours, it decreased to half at the? To level, but the transition of the clear electrochromic compound between the colored state and the bleached state also appeared after 24 hours of operation.

[ Experimental Example  5: Cyclic Voltage Curve ( CV ) Measure]

The cyclic voltammetric curves of the electrochromic device including the electrochromic compound (CNPhV ²⁺ ₎ of Reference Example 1 and the electrochromic compound (TFMFPhV ^{2 +} ₎ of Example 1 were compared to clarify the origin of the difference in device stability. dmFc functioned as an internal reference material as well as a bipolar species. The redox potential of the EC material was calculated based on the redox potential of dmFc ⁺ / dmFc. The redox peak (redox peak) at -0.23 V against Reference Example 1 (CNPhV ^{2 +} / CNPhV ⁺ ) and the redox peak at -0.35 V against Example 1 (TFMFPhV ^{2 +} / TFMFPhV ⁺ (Redox peak) was determined by taking an intermediate potential corresponding to the coloring voltage.

Specifically, using a platinum disk, Ag wire, and ITO coated glass as working electrode, reference electrode, and counter electrode, respectively, a cyclic voltammetric curve (CV) at a potentiostat at a sweep rate of 50 mV / Are recorded, and are shown in Figs.

11 is a cyclic voltage-current curve (CV) showing the oxidation-reduction stability of the electrochromic device including Reference Example 1. Fig. The graph shows that the anodic peak is not clear and the corresponding negative peak suddenly decreases as the voltage sweep progresses. This indicates that the bleaching behavior of the electrochromic device including Reference Example 1 is irreversible, and the operation stability is poor.

12 is a cyclic voltage-current curve (CV) of the electrochromic device including Example 1. Fig. The graph shows that a significantly symmetric anode and cathode peaks were detected.

The peak of the negative electrode was relatively lower than that of FIG. 11, but the CV of FIG. 12 was slightly decreased at the two peaks of the negative and positive electrodes. This indicates that the electrochemical stability of the electrochromic compound chromophore is closely related to the performance of the electrochromic device.

13 is a cyclic voltage-current curve (CV) of the electrochromic device including Example 2. Fig. The above graph shows that a less stable anode and cathode peaks are detected as compared with Fig.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

Claims (9)

An electrochromic compound represented by the following formula (3):
(3)

In Formula 3, A ^- is an anion. delete delete The method according to claim 1,
Wherein the anion is any one selected from the group consisting of TFSI ^- (bis (trifluoromethylsulfonyl) imide), PF ₆ ^- , BF ₄ ^-, and combinations thereof. A pair of electrodes; And
And an electrochromic layer disposed between the pair of electrodes,
Wherein the electrochromic layer comprises an ion gel and an electrochromic compound represented by the following Formula 3:
(3)

In Formula 3, A ^- is an anion. 6. The method of claim 5,
Wherein the ionic gel comprises a polymer matrix and an ionic salt in a liquid state at room temperature. The method according to claim 6,
The polymer matrix may comprise,
A polymer of any one of poly (vinylidene fluoride) and poly (styrene); And
Any one selected from the group consisting of poly (hexafluoropropylene), poly (ethylene oxide), poly (alkyl methacrylate), and poly (alkyl acrylate);
Wherein the electrochromic device is a co-polymer of an electrochromic device. The method according to claim 6,
The ionic salt in the liquid state at room temperature is preferably 1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) imide, [EMI] [TFSI] ), 1-ethyl-3-methylimidazolium hexafluorophosphate, [EMI] [PF ₆ ]), 1-ethyl-3-methylimidazolium tetrafluoroborate 1-ethyl-3-methylimidazolium tetrafluoroborate, [EMI] [BF ₄ ], 1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) 1-butyl-3-methylimidazolium hexafluorophosphate, [BMI] [PF ₆ ]), 1-butyl-3-methylimidazolium hexafluorophosphate methyl-imidazolium tetrafluoroborate (1-butyl-3-methylimidazolium tetrafluoroborate, [BMI] [BF 4]) , and any one of the former being selected from the group consisting of Color transfer element. A pair of electrodes; And an electrochromic layer positioned between the pair of electrodes, wherein the electrochromic layer comprises an ion gel and an electrochromic compound represented by the following formula (3)
An ON step of supplying an electric current for a predetermined time; And
Turning off the current for a predetermined time; Lt; / RTI &gt;
The ON step; And an OFF step are performed at an intersection.
(3)

In Formula 3, A ^- is an anion.

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