Method for preparing an electrochromic device

Abstract

A method for preparing an electrochromic device. In the method the device is prepared by inserting monovalent cations into a reducing electrochromic layer in advance, for instance, through a dry process. In particular, the method involves inserting monovalent cations into an electrochromic layer which includes a reducing electrochromic material. Then, subsequently and sequentially, placing an electrolyte layer and an ion storage layer on the electrochromic layer. In this way, it is possible to improve driving durability of the electrochromic device.

Claims

1. A method for preparing an electrochromic device, comprising: inserting monovalent cations into an electrochromic layer comprising a reducing electrochromic material; and laminating the electrochromic layer and an ion storage layer via an electrolyte layer, wherein both the electrochromic layer and the ion storage layer are laminated in a colored state; the monovalent cations are inserted into the electrochromic layer by thermal evaporation deposition; the thermal evaporation deposition is performed under conditions of a pressure of 10 mTorr or less and a temperature in a range of 500° C. to 700° C.; wherein the thermal evaporation deposition is performed so that a separate metal layer composed of a source of monovalent cations is not formed; and a content of monovalent cations inserted into the electrochromic layer is in a range of 1.0×10.sup.−8 mol to 1.0×10.sup.−6 mol, wherein the mole number of the monovalent cations inserted into the electrochromic layer is equal to a mole number of electrons present per cm.sup.2 of the electrochromic layer which is obtained by dividing a charge quantity (C/cm.sup.2) of the electrochromic layer with the Faraday constant (C/mol).

2. The method for preparing an electrochromic device according to claim 1, wherein the monovalent cations are selected from the group consisting of Li.sup.+, Na.sup.+, K.sup.+, Rb.sup.+ and Cs.sup.+.

3. The method for preparing an electrochromic device according to claim 1, wherein the electrochromic layer comprises one or more oxide of one or more metal selected from the group consisting of It, Nb, Mo, Ta and W.

4. The method for preparing an electrochromic device according to claim 3, further comprising a step of forming the electrochromic layer on a conductive base material using roll-to-roll equipment.

5. The method for preparing an electrochromic device according to claim 4, comprising steps: unwinding the conductive base material from the roll-to-roll equipment; and forming the electrochromic layer on the unwound conductive base material by a deposition method.

6. The method for preparing an electrochromic device according to claim 5, wherein the deposition method is sputtering deposition, and the sputtering deposition is performed under conditions of a pressure of 1 mTorr to 100 mTorr and a power of 50 W to 500 W.

7. The method for preparing an electrochromic device according to claim 1, wherein the electrolyte layer comprises a gel polymer electrolyte formed from a composition comprising a metal salt that provides monovalent cations that are the same as the monovalent cations inserted into the electrochromic layer, an organic solvent, and a crosslinkable monomer.

8. The method for preparing an electrochromic device according to claim 1, wherein the ion storage layer is a porous layer formed from a coating composition comprising particles having electrochromism.

9. The method for preparing an electrochromic device according to claim 8, wherein the ion storage layer is formed by applying a coating composition comprising (a) one or more oxide particle of one or more metal selected from the group consisting of Cr, Mn, Fe, Co, Ni, Rh, and Irk; or (b) Prussian blue particles, on a second conductive base material, followed by heat treatment.

Description

BEST MODE

(1) Hereinafter, the present application will be described in detail through examples. However, the scope of protection of the present application is not limited by the following examples.

(2) Method for Measurine Driving Characteristics of Electrochromic Film

(3) <Charge Amount>

(4) While changing the driving cycle of the electrochromic film, the charge amount of each film in Examples and Comparative Example was measured by using potential step chronoamperometry (PSCA) using a potentiostat device and the charge amount upon one cycle driving and the charge amount after 500 cycles were compared and described in Table 1.

(5) <Transmittance> Transmittance upon coloring: It means transmittance in a final coloring state observed after elapse of a time (50 s) during which a potential for coloring is applied. The colored film transmittance at the time of driving 500 cycles was described in Table 1. Transmittance upon decoloring: It means transmittance in a final decoloring state observed after elapse of a time (50 s) during which a potential for decoloring is applied. The decolored film transmittance at the time of driving 500 cycles was described in Table 1.

(6) <Discoloration Rate> Coloring time (unit: second): When the transmittance in a final coloring state observed after elapse of a time (50 s) during which a potential for coloring is applied is set to 100, it means a time taken to reach a level of 80. The time taken to be colored until the decolored film satisfies the above level at the time of driving 500 cycles was described in Table 1. Decoloring time (unit: second): When the transmittance in a final decoloring state observed after elapse of a time (50 s) during which a potential for decoloring is applied is set to 100, it means a time taken to reach a level of 80. The time taken to be decolored until the colored film satisfies the above level at the time of driving 500 cycles was described in Table 1.

EXAMPLES AND COMPARATIVE EXAMPLE

Example 1

(7) On an ITO/PET laminate with a thickness of 250 nm, a WO.sub.3 layer with a thickness of 300 nm was laminated using a sputtering method (process pressure 15 mTorr, deposition power 200 W, and deposition time 30 minutes). Specifically, using the roll-to-roll equipment, the laminate film was unwound from the roll on which the film was wound and simultaneously the WO.sub.3 layer was formed on one side of the ITO of the unwound film Thereafter, lithium ions (Li.sup.+) were inserted into WO.sub.3 of an ITO/WO.sub.3 laminate under conditions of 10.sup.−6 Torr and 640° C. using a thermal evaporation deposition method, and the WO.sub.3 layer was colored. At this time, the time for performing the thermal evaporation deposition is 10 seconds, and the lithium doping amount is 2.0363×10.sup.−7 (mol/cm.sup.2).

(8) Then, the ITO/WO.sub.3 laminate was bonded to a PB/ITO/PET laminate via a gel polymer electrolyte (GPE) with a thickness of 150 nm to prepare an electrochromic film with a PET/ITO/WO.sub.3/GPE/PB/ITO/PET structure. Thus, before the actual driving, the electrochromic film had a relatively low light transmission characteristic (colored state). The PB layer was prepared by coating a coating solution containing 30 wt % of Prussian blue particles having a diameter of 20 nm, 65 wt % of ethanol and 5 wt % of TEOS (tetraethoxysilane) on the ITO with a bar coater and then drying it at 110° C. for 5 minutes. The thickness of the PB layer is 250 nm.

(9) For the film, the transmittance, the driving charge amount and the discoloration rate were observed while applying decoloring and coloring voltages of +2V per cycle for 50 seconds, respectively. The results are shown in Table 1.

Example 2

(10) An electrochromic film having the same structure was prepared in the same manner as in Example 1, except that the time during which the thermal evaporation deposition was performed was 20 seconds (lithium doping amount 3.1090×10.sup.−7 (mol/cm.sup.2)).

Example 3

(11) An electrochromic film having the same structure was prepared in the same manner as in Example 1, except that the time during which thermal evaporation deposition was performed was 30 seconds (lithium doping amount 4.1090×10.sup.−7 (mol/cm.sup.2)).

Comparative Example 1

(12) An electrochromic device having the same lamination structure as in Example 1 was prepared in the same manner as in Example 1, except that the process of inserting lithium ions by thermal deposition was omitted.

(13) Thereafter, a voltage of −5 V was applied to the PB/ITO side of the film for 3 minutes to decolor the PB. Thus, the electrochromic film had a relatively high light transmission characteristic before actual driving. For the film, the transmittance, the driving charge amount and the discoloration rate were observed while applying decoloring and coloring voltages having the same size at the same time intervals. The results are shown in Table 1.

(14) TABLE-US-00001 TABLE 1 Lithium doping Driving charge Transmittance Discoloration rate time by thermal amount (mC) (%, 500 cycle) (second, 500 cycle) deposition 1 cycle 50 cycle Colored Decolored Colored Decolored Comparative 0 148 14 51 68 16 16 Example 1 Example 1 10 seconds 250 50 40 70 15 18 Example 2 20 seconds 285 300 25 70 15 19 Example 3 30 seconds 302 301 24 70 19 17

(15) From Table 1, it can be seen that as the driving time elapses, the decrease width in the driving charge amount and the colored/decolored transmittance observed in the film of Comparative Example is larger than that in Examples. This means that the long-term driving durability of the films produced according to Examples is superior to that of Comparative Example.