Temperature-light-controlled dual-band electrochromic mirror system for next-generation smart window

Abstract

The present invention relates to a temperature-light-controlled dual-band electrochromic mirror system for a next-generation smart window, the system being capable of implementing a colored mode and a colored mirror mode through the adjustment of applied voltage, selectively blocking or absorbing visible light and near-infrared rays, and minimizing light reflection in the colored mirror mode so as to prevent glare. The temperature-light-controlled dual-band electrochromic mirror system for a next-generation smart window, according to the present invention, comprises: first and second electrodes arranged to face each other and be spaced apart from each other; a cathodic counterpart provided on the second electrode; and an electrolyte which is provided between the first electrode and the second electrode and which includes an organic chromic material and an inorganic chromic material, wherein the optical state is switched to any one from among a transparent mode, the colored mode and the colored mirror mode according to the application of voltage.

Description

A temperature-light-controlled dual-band electrochromic mirror system for next-generation smart windows.

[0001] Cross-reference to related applications: This application claims priority to Korean Patent Application No. 10-2024-0115757, which is incorporated herein by reference.

[0002] The present invention was made under the support of the Ministry of Science and ICT of the Republic of Korea under the task identification number 1711200109 and task number RS-2023-00283244. The management expert organization of the said task is the National Research Foundation of Korea. The research project name is “Nanomaterial Technology Development”, the research project title is “Development of Next-Generation Electrochromic Platform Capable of Simultaneous Light-Heat Control with Meter-Level Scale High Transmittance”, and the research period is from 2023.08.01 to 2026.06.30.

[0003] The present invention relates to a temperature-light controlled dual-band electrochromic mirror system for next-generation smart windows, and more particularly, to a temperature-light controlled dual-band electrochromic mirror system for next-generation smart windows, which can not only implement a tinting mode and a tinting-based mirror mode by controlling an applied voltage, but also selectively block or absorb visible light and near-infrared light while minimizing light reflection in the tinting-based mirror mode to prevent the occurrence of a glare phenomenon.

[0004] Smart windows can reversibly switch between transparent and blocking states, allowing them to selectively transmit or block light. Smart windows can be implemented in a variety of ways, but electrochromic devices are a prime example.

[0005] Electrochromic devices are devices that can reversibly switch their optical states by inducing redox reactions in electrochromic materials. Research has been conducted on various electrochromic materials. For example, metal oxides such as WO3 and TiO2, conductive polymers such as PANI (polyaniline) and PEDOT:PSS, and metal salts such as Ag have been applied as electrochromic materials.

[0006] Among these, metal oxides and conductive polymers offer control over visible light and near-infrared light, but they struggle to achieve a wide color spectrum and suffer from low transmittance contrast. While silver-based electrochromic devices can effectively block visible light and near-infrared light through mirror mode, they inevitably suffer from glare due to light reflection. This glare is a critical issue that must be addressed when applying them to building windows.

[0007] That is, in implementing a smart window based on an electrochromic device, a solution must be presented for the phenomenon of glare caused by light reflection in mirror mode, as well as fast response to reversible switching of optical states and low-voltage operation.

[0008] [Prior Art Literature]

[0009] [Patent Document]

[0010] (Patent Document 1) Korean Patent Registration No. 1595504 (Published on February 17, 2016)

[0011] (Patent Document 2) U.S. Patent Publication No. US 2024-0094589 (published on March 21, 2024)

[0012] (Patent Document 3) U.S. Patent Publication No. US 8865998 (registered on October 21, 2014)

[0013] The present invention has been devised to solve the above problems, and the purpose of the present invention is to provide a next-generation smart window temperature-light control dual-band electrochromic mirror system that can not only implement a coloring mode and a coloring-based mirror mode by controlling an applied voltage, but also prevent the occurrence of glare by minimizing light reflection in the coloring-based mirror mode while selectively blocking or absorbing visible light and near-infrared light.

[0014] In order to achieve the above object, the next-generation smart window temperature-light control dual-band electrochromic mirror system according to the present invention comprises: a first electrode and a second electrode spaced apart from each other; an anode counter electrode provided on the second electrode; and an electrolyte including an organic chromic material and an inorganic chromic material provided between the first electrode and the second electrode; characterized in that it switches to any one optical state among a transparent mode, a colored mode, and a colored-based mirror mode according to an application of a voltage.

[0015] As the applied voltage increases, it can sequentially switch from transparent mode to colored mode, and from colored mode to colored-based mirror mode.

[0016] Organic color-changing materials are materials that can change color when power is applied and have the ability to block or absorb visible light, while inorganic color-changing materials are materials that can form a mirror when power is applied and can block visible light and near-infrared light.

[0017] In transparent mode, the anode counterpart is in a reduced state, in colored mode, the organic chromophore is reduced and colored, and in colored-based mirror mode, the inorganic chromophore is reduced while the coloring of the organic chromophore is maintained.

[0018] The organic discoloring material is one or a combination of diheptyl viologen (DHV), a pyridine-based compound, and an aminoquinone-based compound, and the inorganic discoloring material is a metal salt containing at least one of Ag, Cu, and Au, and the anode counter species is one of Prussian blue (PB), WO3, and Co3O4.

[0019] When the organic discoloration material is DHV, the inorganic discoloration material is Ag, and the anode counter species is Prussian blue (PB), in transparent mode, Prussian blue (PB) is reduced to Prussian white (PW), and in colored mode, DHV present in the electrolyte 2+ Go to DHV 0 DHV is colored by being reduced to Ag, and in the color-based mirror mode, the coloration of DHV is maintained. + Go Ag 0 is reduced to form an Ag mirror on the first electrode.

[0020] As the applied voltage increases in the opposite direction, the organic discoloration material changes from a reduced state to an oxidized state, the inorganic discoloration material changes from a reduced state to an oxidized state, and the anode counterpart changes from a reduced state to an oxidized state sequentially.

[0021] Organic and inorganic discoloring substances are cathode redox substances.

[0022] DHV and Ag exist in the form of DHV(Br)2 and AgNO3, respectively, and the electrolyte contains a combination of LiCl and TBABr3.

[0023] The next-generation temperature-light controlled dual-band electrochromic mirror system for smart windows according to the present invention has the following effects.

[0024] It is possible to implement optical states of transparent mode, colored mode, and colored-based mirror mode. In addition, since selective blocking and absorption of visible light and near-infrared light are possible, indoor temperature control is possible when applied to windows. In addition, in the colored-based mirror mode, the Ag mirror is formed while maintaining the colored DHV, so that the light reflected to the outside from the Ag mirror is absorbed by the colored DHV, thereby preventing the glare phenomenon caused by light reflection.

[0025] FIG. 1 is a schematic diagram of a temperature-light controlled dual-band electrochromic mirror system for a next-generation smart window according to one embodiment of the present invention.

[0026] Figure 2 is a schematic diagram showing a temperature-light control dual-band electrochromic mirror system for a next-generation smart window manufactured by Experimental Example 1.

[0027] Fig. 3a is a UV-NIR spectrum profile showing the transmittance by wavelength according to various applied voltages, Fig. 3b is a UV-NIR spectrum profile showing the transmittance by wavelength according to various applied times, and Fig. 3c is a photograph showing the optical state of an electrochromic mirror system according to various applied voltages.

[0028] Figure 4 shows the CV profile and transmittance characteristics according to the applied voltage.

[0029] Figure 5 shows the time required for coloring and decolorization and the difference in transmittance (ΔT max ) is shown.

[0030] Figure 6 shows the change in transmittance when the transparent mode, colored mode, and colored-based mirror mode are repeated for 35,000 seconds.

[0031] Fig. 7a is a photograph of a wooden model house according to Experimental Example 4, and Figs. 7b to 7d show the results of thermal control analysis according to Experimental Example 4.

[0032] Figures 8a and 8c show the reflectivity by wavelength and photographs of each mode of an electrochromic mirror system to which DHV is not applied, and Figures 8b and 8d show the reflectivity by wavelength and photographs of each mode of an electrochromic mirror system manufactured by Experimental Example 1.

[0033] The present invention proposes a next-generation temperature-light-controlled dual-band electrochromic mirror system for smart windows, utilizing an organic chromic material, an organic chromic material, and an anode counterpart as electrochromic materials. In the present invention, the electrochromic mirror system may refer to an electrochromic element.

[0034] The next-generation temperature-light controlled dual-band electrochromic mirror system for smart windows according to the present invention can be selectively switched to any one of transparent mode, colored mode, and colored mirror mode depending on an applied voltage.

[0035] In the present invention, the organic color-changing material is a material that can change color when power is applied and has the ability to block or absorb visible light. As an example, any one or a combination of diheptyl viologen (hereinafter referred to as 'DHV'), a pyridine-based compound, and an aminoquinone-based compound may be used. The inorganic color-changing material is a material that can form a mirror when power is applied and can block visible light and near-infrared rays. A metal salt containing at least one of Ag, Cu, and Au may be used. As the anode counterpart, any one of Prussian blue (Fe4[Fe(CN)6]3), WO3, and Co3O4 may be used.

[0036] The next-generation temperature-light control dual-band electrochromic mirror system for smart windows according to the present invention, in which an organic chromic material, an inorganic chromic material, and an anode counter-species are applied as electrochromic materials, can be selectively switched to any one of a transparent mode, a colored mode, and a colored mirror mode depending on an applied voltage. Taking DHV as the organic chromic material, Ag as the inorganic chromic material, and Prussian blue (PB) as the anode counter-species as an example, the transparent mode, the colored mode, and the colored mirror mode will be described as follows.

[0037] The transparent mode means that the electrochromic mirror system becomes transparent when Prussian blue (PB) is reduced to Prussian white (PW), and the colored mode means that the DHV becomes discolored when a second voltage is applied to the electrochromic mirror system, and the colored mirror mode means that the Ag ions of the Ag ions are transferred when a third voltage is applied and the coloring of the DHV is maintained. 0 This refers to a state in which an Ag mirror is formed due to reduction. Here, the third voltage is a value greater than the second voltage, and therefore, in the process of increasing the applied voltage, the transition occurs from transparent mode to colored mode, and from colored mode to colored-based mirror mode. For reference, Prussian white (PW) is oxidized to Prussian blue (PB) through a step in which a first voltage smaller than the second voltage is applied, and this step may correspond to the colored mode.

[0038] In the coloring mode, visible light is blocked by the colored DHV, and in the coloring-based mirror mode, visible light and near-infrared light are blocked by the Ag mirror. As described above, as the applied voltage increases, the mode switches between the coloring mode and the coloring-based mirror mode, and selective blocking of visible light and near-infrared light is possible by adjusting the applied voltage.

[0039] Meanwhile, one of the important aspects of the present invention is that the mirror mode is achieved in a colored state. That is, in the present invention, the colored mirror mode refers to a state in which an Ag mirror is formed while maintaining the coloring of the DHV.

[0040] Since the Ag mirror is formed in a state where the DHV is colored, in addition to the visible light and near-infrared light blocking effect of the Ag mirror, a visible light absorption effect by the colored DHV can be additionally obtained. For example, the next-generation temperature-light control dual-band electrochromic mirror system for a smart window of the present invention comprises opposing first and second substrates, an electrolyte including a DHV is provided between the first and second substrates, the first substrate is arranged to face the interior, and the second substrate is arranged to face the exterior, and in the coloring-based mirror mode, an Ag mirror is formed on the first substrate, and external light (visible light and near-infrared light) is blocked by the Ag mirror, and at the same time, light (visible light) reflected by the Ag mirror is absorbed by the colored DHV.

[0041] This coloring-based mirror mode can be said to be the most differentiating part from conventional electrochromic devices. Conventional electrochromic devices are clearly divided into coloring mode and mirror mode, and in the mirror mode, coloring of the electrochromic material does not occur. Therefore, as described above in the 'Background Technology of the Invention', in the case of an electrochromic device that induces the formation of a silver mirror, a glare phenomenon due to light reflection inevitably occurs. On the other hand, as described above, in the present invention, even if light reflection by the silver mirror occurs, since the DHV maintains a colored state, the reflected light is absorbed by the colored DHV, thereby suppressing the glare phenomenon.

[0042] Hereinafter, a next-generation smart window temperature-light controlled dual-band electrochromic mirror system according to one embodiment of the present invention will be described in detail with reference to the drawings.

[0043] Referring to FIG. 1, a next-generation temperature-light controlled dual-band electrochromic mirror system for a smart window according to one embodiment of the present invention comprises first and second electrodes that are arranged in opposite directions. An electrolyte containing an organic chromic material and an inorganic chromic material is provided between the first and second electrodes. When power is applied to the first and second electrodes, the optical states are reversibly switched by a redox reaction of the organic chromic material, the inorganic chromic material, and the anode counterpart layered on the second electrode.

[0044] The first electrode is provided on a first substrate, and the second electrode is provided on a second substrate. The first substrate and the second substrate are made of a transparent insulating material. In one embodiment, a glass substrate, a transparent polymer substrate, or the like can be used as the first substrate and the second substrate. The first electrode and the second electrode are also made of a transparent conductive material, and in one embodiment, may be made of a transparent conductive oxide such as ITO (indium tin oxide), but is not limited thereto.

[0045] The first electrode serves as a working electrode, the second electrode serves as a counter electrode, and an anode counter species is deposited in the form of a thin film on the second electrode. The anode counter species deposited in the form of a thin film on the second electrode serves to balance the stoichiometry as an anode counter species during the redox reaction of the electrochromic material when power is applied. Any one of Prussian blue (Fe4[Fe(CN)6]3), WO3, and Co3O4 can be used as the anode counter species.

[0046] The organic and inorganic discoloring materials described below correspond to cathode oxidation-reduction materials.

[0047] An electrolyte containing an organic chromic material and an inorganic chromic material is provided between the first electrode and the second electrode. In the present invention, the organic chromic material is a material that can change color when power is applied and has the ability to block or absorb visible light. As an example, any one or a combination of diheptyl viologen (hereinafter referred to as 'DHV'), a pyridine-based compound, and an aminoquinone-based compound may be applied. The inorganic chromic material must be a material that can form a mirror when power is applied and can block visible light and near-infrared rays, and a metal salt containing at least one of Ag, Cu, and Au may be applied. Hereinafter, a description will be made with an example in which DHV is applied as the organic chromic material, Ag is applied as the inorganic chromic material, and Prussian blue (PB) is applied as the anode counterpart (see Fig. 1). DHV may be provided in the form of DHV(Br)2 in the electrolyte, and Ag may be provided in the form of AgNO3.

[0048] As described above, DHV and Ag present in the electrolyte are cathode redox substances, and Prussian blue provided on the second electrode acts as an anode counterpart. When power is applied to the first and second electrodes, DHV, Ag, and Prussian blue are oxidized or reduced.

[0049] Specifically, in the case of Prussian Blue (PB), depending on the power supply, Prussian Blue (PB) can be reduced to Prussian White (PW) or Prussian White (PW) can be oxidized to Prussian Blue (PB). In the case of DHV, depending on the power supply, DHV 2+ Go to DHV + Through DHV 0 reduced to or conversely DHV 0 Go to DHV + Through DHV 2+ can be oxidized. In the case of Ag, depending on the power supply, Ag + Go Ag 0 or reduced to Ag 0 Go Ag +can be oxidized to

[0050] When Prussian Blue (PB) is reduced to Prussian White (PW), the electrochromic mirror system becomes transparent, and DHV 2+ Go to DHV 0 When reduced to , the electrochromic mirror system becomes colored by the coloring of DHV, and Ag + Go Ag 0 When reduced to Ag, a Ag mirror is formed, and the electrochromic mirror system becomes a mirror state. When the oxidation or reduction of each substance occurs in reverse, the electrochromic mirror system becomes in the opposite state, which will be described in detail later.

[0051] Prussian white (PW) and colored DHV block or absorb visible light, while Ag mirrors block visible light and near-infrared light.

[0052] The electrolyte has no particular limitations on its composition, but as an example, a combination of LiCl and TBABr3 can be used. In addition, a non-volatile solvent, such as dimethyl sulfoxide (DMSO), may be provided together with the electrolyte to dissolve the electrolyte, DHV(Br)2, and AgNO3. In addition, a binder, such as polyvinyl alcohol (PVA), may be further included in the electrolyte to ensure physical bonding and mechanical strength between the first and second electrodes. In addition, a spacer may be further provided to separate the first and second electrodes.

[0053] Under the above configuration, the next-generation temperature-light controlled dual-band electrochromic mirror system for smart windows according to one embodiment of the present invention can achieve three optical states, namely, transparent mode, tinted mode, and tinted mirror mode, depending on the power supply. The transparent mode, tinted mode, and tinted mirror mode are described as follows.

[0054] Transparent mode

[0055] The Prussian blue (PB) on the second electrode is reduced to Prussian white (PW), and the electrochromic mirror system is in a transparent state. A certain voltage can be applied to the first electrode to reduce Prussian blue (PB) to Prussian white (PW), and this state corresponds to the initial state and transparent mode. In the experimental example described below, a voltage of 1.5 V was applied to the first electrode to convert Prussian blue (PB) to Prussian white (PW), thereby forming the initial state.

[0056] Coloring mode

[0057] By sequentially applying the first voltage and the second voltage to the first electrode, Prussian white (PW) is oxidized into Prussian blue (PB) and DHV 2+ to DHV 0 The electrochromic mirror system can be converted into a colored mode by reducing it to .

[0058] Specifically, Prussian white (PW) is oxidized to Prussian blue (PB) by the application of the first voltage, and DHV is oxidized to Prussian blue (PB) by the application of the second voltage. 2+ Go to DHV 0 is reduced to . The second voltage is a value greater than the first voltage, and each of the first voltage and the second voltage may represent a predetermined voltage range. In one embodiment, a voltage greater than 0 and less than or equal to -1.3 V may be applied as the first voltage, and a voltage greater than -1.3 V and less than or equal to -2.0 V may be applied as the second voltage. Additionally, the first voltage and the second voltage may be applied continuously.

[0059] When Prussian white (PW) is oxidized to Prussian blue (PB) by applying a first voltage, the change in transmittance of the electrochromic mirror system is minimal. In particular, the decrease in transmittance is less than 10% in the visible light range (wavelength 600 nm), and even in the near-infrared range (wavelength 1000 nm), the decrease in transmittance is at most about 20%. In other words, even when Prussian white (PW) is oxidized to Prussian blue (PB), the transmittance remains above 80%.

[0060] On the other hand, DHV by application of second voltage 2+ Go to DHV 0 During the reduction process, the transmittance decreases rapidly. In the visible light range (600 nm), the transmittance decreases to about 20%, and in the near-infrared range (1000 nm), the transmittance decreases to about 60%. This change in transmittance value can be said to be a visually (visible light range) colored state of the electrochromic mirror system, which means that visible light is blocked or absorbed by the coloring of the DHV. However, since a certain level of transmittance (about 60%) is still shown in the near-infrared range (1000 nm), it can be seen that a significant amount of near-infrared light passes through the electrochromic mirror system.

[0061] In summary, the color mode is practically DHV by applying a second voltage. 2+ Go to DHV 0 It is generated in the process of being reduced to, and through the coloring mode, visible light can be blocked (or absorbed) and near-infrared light can be transmitted. Since only visible light among visible light and near-infrared light can be selectively blocked through the coloring mode, it can be utilized for the purpose of achieving both privacy protection and indoor heat retention when applying the electrochromic element to actual windows. Here, only the stage where the second voltage is applied can be defined as the coloring mode.

[0062] For reference, DHV 2+ Go to DHV 0 In the process of being reduced to, more precisely, DHV2+ Go to DHV + Through DHV 0 It is reduced to , at which time DHV 2+ Go to DHV + In the process of reduction, the change in transmittance is actually made, and DHV + Go to DHV 0 In the process of being reduced to , the change in transmittance is minimal. Accordingly, in Fig. 4 described below, 'DHV + →DHV 0 ' The reaction display was omitted.

[0063] Color-based mirror mode

[0064] When a third voltage is applied to the first electrode, Ag + Go Ag 0 is reduced to, and the reduced Ag 0 Silver is deposited on the first electrode, and an Ag mirror is formed on the first electrode. The third voltage is a value greater than the second voltage of the coloring mode, and in one embodiment, a voltage greater than -2.0 V and less than -2.5 V may be applied as the third voltage. Here, the order of magnitude of the first to third voltages is clear, but the specific values ​​of the first to third voltages may vary depending on the constituent materials and geometric structure of the electrochromic mirror system.

[0065] In this way, the coloring-based mirror mode is implemented by forming the Ag mirror. The coloring-based mirror mode means that the Ag mirror is formed while maintaining the coloring. As the Ag mirror is formed while maintaining the coloring, the transmittance decreases significantly. The transmittance in the visible light range (600 nm) converges to 0, and the transmittance in the near-infrared range (1000 nm) also decreases to a level of less than about 4%. This transmittance characteristic means that both visible light and near-infrared light are blocked by the Ag mirror. In particular, in the previous coloring mode, the transmittance decrease progressed rapidly in the visible light range (600 nm), whereas in the coloring mode mirror mode, the transmittance decrease progressed rapidly in the near-infrared range (1000 nm).

[0066] In addition, as the coloring of the DHV is maintained, the light (visible light) reflected by the Ag mirror is absorbed by the colored DHV. That is, when the first electrode is arranged facing indoors and the second electrode is arranged facing outdoors, and the Ag mirror is formed on the first electrode, external light can be reflected by the Ag mirror, and at this time, the reflected light (visible light) is absorbed by the colored DHV, and accordingly, no glare phenomenon occurs due to the reflected light. This can be confirmed through the experimental example described below.

[0067] As discussed above, in the coloring mode, a significant decrease in transmittance in the visible light range (600 nm) can be induced by the reduction of DHV, and in the coloring-based mirror mode, a rapid decrease in transmittance in the near-infrared range (1000 nm) can be induced. In addition, it can be said that in the coloring mode, visible light is mainly blocked, and in the coloring-based mirror mode, near-infrared light is mainly blocked. In addition, in the coloring-based mirror mode, since the coloring of the DHV is maintained, the light reflected by the Ag mirror can be prevented from being absorbed by the colored DHV, thereby preventing a glare phenomenon from occurring due to the reflected light.

[0068] Restore to transparent mode

[0069] Meanwhile, restoration from the tinting-based mirror mode to the transparent mode is achieved by applying a reverse voltage. Specifically, by reducing the applied voltage (e.g., down to -1.7 V) from the tinting-based mirror mode state (e.g., -2.5 V applied), the DHV 0 DHV 2+ The process of oxidation, Ag 0 Ag + The process of oxidizing Prussian blue (PB) and reducing Prussian white (PW) are sequentially performed to restore the transparent mode.

[0070] In the above process, DHV 0 Go to DHV 2+ Even if the Ag mirror is still maintained even when the Ag is oxidized and the DHV is discolored, the change in transmittance is not large, and the Ag 0 Go Ag + When the Ag mirror state is released by oxidation, the transmittance is restored to approximately 75%. Then, the Prussian blue (PB) is reduced to Prussian white (PW), restoring the transmittance to over 90%.

[0071] Hereinafter, an electrochromic mirror system according to one embodiment of the present invention has been described. Meanwhile, an electrochromic mirror system having the above-described configuration can be manufactured by the following method, as an embodiment. A first substrate provided with a first electrode and a second substrate provided with a second electrode are prepared, and Prussian blue is deposited on the second electrode through a process such as electrodeposition, and then an electrolyte containing DHV and Ag is interposed between the first and second electrodes, thereby completing the electrochromic mirror system. At this time, a method may be used in which an electrolyte containing DHV and Ag is cast on the first electrode, and then the second substrate is laminated so that the second electrode is in contact with the electrolyte.

[0072] Next, the present invention will be explained in more detail through experimental examples.

[0073] Experimental Example 1: Fabrication of a Temperature-Light Controlled Dual-Band Electrochromic Mirror System for Next-Generation Smart Windows

[0074] A solution containing 100 mM KNO3, 100 mM HNO3, 10 mM Fe(NO3)3·9H2O and 10 mM K3Fe(CN)6 in ultrapure water was prepared, and the cyclic voltammetry method (50 μA cm -2 A Prussian blue (PB) thin film layer was formed on ITO using a voltage of 0∼1 V, 5 cycles. Then, it was washed with ultrapure water and ethanol, and dried at 80°C for 2 hours.

[0075] An EC gel electrolyte was prepared by dissolving 100 mM AgNO3, 80 mM DHV(Br)2, 500 mM LiCl, and 200 mM TBABr3 in DMSO, and 10 wt% PVA was additionally added to the EC gel electrolyte.

[0076] The manufactured EC gel electrolyte was cast onto bare ITO (the first electrode), and then an ITO (the second electrode) with a Prussian blue (PB) thin film layer formed thereon was bonded to complete the electrochromic mirror system. At this time, double-sided tape was used as a spacer. Figure 2 is a schematic diagram showing the electrochromic mirror system manufactured according to Experimental Example 1.

[0077] Experimental Example 2: Changes in optical state according to applied voltage

[0078] To optimize the applied voltage and time of the electrochromic mirror system manufactured by Experimental Example 1, various conditions were applied. Fig. 3a is a UV-NIR spectral profile showing the transmittance by wavelength according to various applied voltages, Fig. 3b is a UV-NIR spectral profile showing the transmittance by wavelength according to various applied times, and Fig. 3c is a photograph showing the optical state of the electrochromic mirror system according to various applied voltages.

[0079] Referring to Figures 3a and 3c, it can be confirmed that three optical states are realized depending on the applied voltage. The initial state is transparent, and there is almost no change in transmittance until the applied voltage increases to -1.3 V. Then, when the applied voltage increases to -1.6 V, the DHV 2+ Go to DHV 0 When reduced to , it takes on a deep blue color. At this time, the transmittance is reduced to about 20% at a wavelength of 600 nm, which is in the visible light range. In this state, when the applied voltage is increased to -2.0 V, Ag + Go Ag 0 Reduced Ag with reduction to 0 Ag is deposited on the first electrode (bare ITO) to form an Ag mirror, and the transmittance is less than 1%.

[0080] Figure 3c shows the transmittance by wavelength when the applied voltage is fixed at -2 V and the applied time is applied differently at 15 seconds, 30 seconds, 45 seconds, and 60 seconds. It can be confirmed that the transmittance decreases rapidly after 15 seconds have passed, and the transmittance converges to 0% after 45 seconds have passed.

[0081] Experimental Example 3: Transmittance characteristics and CV profile according to applied voltage

[0082] Figure 4 shows the CV profile and transmittance characteristics according to the applied voltage. In Figure 4, the transmittance is shown for each of the 600 nm and 1000 nm wavelengths. For reference, the top graph in Figure 4 shows the CV profile according to the applied voltage, the middle graph in Figure 4 shows the transmittance at a 600 nm wavelength, and the bottom graph shows the transmittance at a 1000 nm wavelength.

[0083] The results of Fig. 4 show that the CV profile and the transmittance characteristics according to the applied voltage are consistent with each other. The CV profile and transmittance characteristics of Fig. 4 can be broadly divided into eight stages (Stage 1 to Stage 8) as follows.

[0084] Step 1: PW → PB (oxidation)

[0085] Step 2: DHV 2+ → DHV + (restoration)

[0086] Step 3: DHV + → DHV 0 (restoration)

[0087] Stage 4: Ag + → Ag 0 (restoration)

[0088] Step 5: DHV 0 → DHV + (oxidation)

[0089] Step 6: DHV + → DHV 2+ (oxidation)

[0090] Step 7: Ag 0 → Ag + (oxidation)

[0091] Step 8: PB → PW (Reduction)

[0092] In the first stage, when the applied voltage increases to -1.3 V, Prussian white (PW) is oxidized to Prussian blue (PB). In the first stage, Li + Since it exists in the electrolyte, no special oxidation-reduction reaction occurs.

[0093] DHV during the process of increasing the applied voltage to -2.0 V through the second and third stages 2+ Go to DHV 0DHV is reduced to coloration, and the transmittance in the visible light region (600 nm) is reduced to about 20%, and the transmittance in the near-infrared region (1000 nm) is reduced to about 64%. At this time, the transmittance reduction occurs mostly in the second stage, and in the third stage (DHV + → DHV 0 ) the decrease in transmittance is minimal. This is because the coloring of DHV in the third stage is a form in which a dull blue is added to the dark blue of the second stage.

[0094] In the fourth step, the applied voltage increases to -2.5 V, and Ag + Go Ag 0 The Ag mirror is formed on the first electrode by reducing the Ag mirror, and both visible light and near-infrared light are blocked by the formation of the Ag mirror, so that the transmittance converges to almost 0%.

[0095] In the 5th step (-1.7 V) and the 6th step (0 V), when the applied voltage is reduced to 0 V in the reverse direction, DHV 0 is DHV 2+ It is oxidized, but there is almost no change in transmittance. This is because the Ag mirror exists.

[0096] Ag in stage 7 0 This Ag + When the Ag mirror is released by reducing to Prussian Blue (PB), the transmittance is restored to 75%, and in the 8th step, when Prussian Blue (PB) is reduced to Prussian White (PW), the transmittance is completely restored to over 94%.

[0097] Meanwhile, Fig. 5 shows the time required for coloring and decolorization and the difference in transmittance (ΔT max ), and the coloring time and decolorization time in the visible light range (600 nm) and the transmittance contrast difference (ΔT max ) were 11 seconds, 76 seconds, and 96%, respectively, and the coloring time, decolorization time, and transmittance contrast difference (ΔT) in the near-infrared region (1000 nm) were max) showed 22 seconds, 38 seconds, and 91%, respectively.

[0098] Fig. 6 shows the change in transmittance when the transparent mode, colored mode, and colored-based mirror mode are repeated for 35,000 seconds. This experiment also measured the transmittance at each wavelength of 600 nm and 1000 nm. At the wavelength of 600 nm, the time to reach +1.5 V, which is the voltage corresponding to the transparent mode, was 5 seconds, the time to reach -2.0 V, which is the voltage corresponding to the colored mode and colored-based mirror mode, was 17 seconds, and the time to reach 0 V, which is the voltage at which the colored mode is released, was 140 seconds. At the wavelength of 1000 nm, 5 seconds (+1.5 V), 30 seconds (-2.0 V), and 70 seconds (0 V) were applied. As a result of the experiment, as shown in Fig. 6, it can be seen that the device operates stably even after 35,000 seconds have elapsed. Although the electrochromic performance of the device deteriorated somewhat as the number of switching cycles increased, it still exhibited excellent transmittance characteristics of ∼88% (600 nm) and ∼86% (1000 nm) compared to the initial transmittance even after 35,000 seconds.

[0099] Experimental Example 4: Thermal Control Characteristics

[0100] The electrochromic mirror system manufactured in Experimental Example 1 was applied as a window to a wooden model house to investigate its thermal control characteristics. The electrochromic mirror system manufactured in Experimental Example 1 was installed on the roof of the wooden model house, and all openings of the wooden model house were sealed with Styrofoam. A halogen lamp (35 W) was installed at a vertical distance of 10 cm from the electrochromic mirror system and light was irradiated for 45 minutes. For comparison, an experiment under the same conditions was also conducted on a wooden model house with general glass applied. Figure 7a is a photograph of the wooden model house according to Experimental Example 4.

[0101] As shown in Fig. 7b, in the case where ordinary glass was applied, the indoor temperature initially at 14.7°C rose to 49.2°C after 45 minutes, whereas in the case of the model house where the electrochromic mirror system was applied, the indoor temperature after 45 minutes was only 18.2°C.

[0102] In more detail, when comparing the tinting mode and tinting-based mirror mode of the electrochromic mirror system with ordinary glass, the temperature difference between ordinary glass and tinting mode was 17.5℃ after 45 minutes, and the temperature difference between ordinary glass and tinting-based mirror mode was 24.8℃ (see Fig. 7c). In addition, when examining the temperature difference between the initial room temperature and the room temperature after 45 minutes, the temperature difference was 29.5℃ for ordinary glass, while the temperature difference in tinting mode was 11℃, and the temperature difference in tinting-based mirror mode was 4℃ (see Fig. 7d). These results show that the thermal control characteristics of the electrochromic mirror system according to the present invention are very excellent.

[0103] Experimental Example 5: Reflectivity Characteristics

[0104] The light reflection characteristics in the color-based mirror mode of the electrochromic mirror system manufactured by Experimental Example 1 were examined. For comparison, an electrochromic mirror system without DHV was manufactured and the light reflection characteristics were examined under the same conditions. Figures 8a and 8c show the reflectivity by wavelength and photographs of each mode of the electrochromic mirror system without DHV applied, and Figures 8b and 8d show the reflectivity by wavelength and photographs of each mode of the electrochromic mirror system manufactured by Experimental Example 1.

[0105] Referring to FIGS. 8a and 8b, in the transparent mode where the mirror mode is not formed, both electrochromic mirror systems exhibited a low outside reflectance of less than 10% in the visible light range (wavelength of 400-800 nm). On the other hand, in the mirror mode, the outside reflectance increased to about 20% in the case of the electrochromic mirror system to which DHV was not applied (see FIG. 8a), but in the case of the electrochromic mirror system manufactured by Experimental Example 1, the outside reflectance value showed a similar result to that in the transparent mode (see FIG. 8b). That is, in the case of the electrochromic mirror system manufactured by Experimental Example 1, the outside reflectance did not increase even when the coloring-based mirror mode was formed.

[0106] To visually verify these results, an experiment was conducted to determine whether light reflection occurred by vertically mounting the electrochromic mirror system and shining a flashlight on the electrochromic mirror system. As can be seen in the rightmost photo (stage 2 (light on)) of Fig. 8c, light is reflected on the floor surface, whereas in the case of the electrochromic mirror system manufactured by Experimental Example 1, no light is reflected on the floor surface (see the rightmost photo (stage 2 (light on)) of Fig. 8d).

[0107] Through the above results, it can be inferred that in the case of the electrochromic mirror system manufactured by Experimental Example 1, light reflected from the Ag mirror to the outside is absorbed by the colored DHV, whereas in the case of the electrochromic mirror system without the DHV applied, light reflected from the Ag mirror is emitted to the outside as is.

Claims

1. A first electrode and a second electrode spaced apart from each other; A positive electrode counter-electrode provided on the second electrode; and It comprises an electrolyte including an organic discoloring material and an inorganic discoloring material, which is provided between a first electrode and a second electrode; An electrochromic device characterized in that it switches to one of the optical states of transparent mode, colored mode, and colored mirror mode depending on the application of voltage.

2. An electrochromic device characterized in that it can sequentially switch from a transparent mode to a colored mode and from a colored mode to a colored-based mirror mode as the applied voltage increases in the first paragraph.

3. An electrochromic device characterized in that in paragraph 1, the organic discoloring material is a material capable of changing color when power is applied and has the ability to block or absorb visible light, and the inorganic discoloring material is a material capable of forming a mirror when power is applied and has the ability to block visible light and near-infrared light.

4. In the first paragraph, in the transparent mode, the positive electrode counterpart is in a reduced state, In the coloring mode, the organic discoloring material is reduced and colored. An electrochromic device characterized in that, in a color-based mirror mode, an inorganic color-changing material is reduced while the color of the organic color-changing material is maintained.

5. In paragraph 1, the organic discoloring material is one or a combination of diheptyl viologen (DHV), a pyridine-based compound, and an aminoquinone-based compound. The inorganic discoloration material is a metal salt containing at least one of Ag, Cu, and Au. An electrochromic device characterized in that the anode counter species is any one of Prussian blue (PB), WO3, and Co3O4.

6. In paragraph 5, if the organic discoloration material is DHV, the inorganic discoloration material is Ag, and the anode counter species is Prussian blue (PB), In transparent mode, Prussian Blue (PB) is reduced to Prussian White (PW). In the coloring mode, DHV present in the electrolyte 2+ Go to DHV 0 DHV is colored by being reduced to In the color-based mirror mode, Ag is maintained while the color of DHV is maintained. + Go Ag 0 An electrochromic device characterized in that an Ag mirror is formed on the first electrode by being reduced to .

7. An electrochromic device characterized in that, in the second paragraph, as the applied voltage increases in the opposite direction, a change from a reduced state of an organic chromic material to an oxidized state, a change from a reduced state of an inorganic chromic material to an oxidized state, and a change from a reduced state of an anode counterpart to an oxidized state sequentially occur.

8. An electrochromic device characterized in that in paragraph 1, the organic discoloration material and the inorganic discoloration material are cathode redox materials.

9. In paragraph 6, DHV and Ag exist in the form of DHV(Br)2 and AgNO3, respectively. An electrochromic device characterized in that the electrolyte comprises a combination of LiCl and TBABr3.

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