Patent Application
20110317243
The present invention relates to an electrically controllable device having variable optical/energy properties, comprising the following multilayer stack:
The electronically conductive layers are denoted by “TCC”, the abbreviation for “transparent conductive coating”, one example of which is a transparent conductive oxide or TCO.
The electroactive medium (EA) is a medium in solution or a gelled medium. It may also be contained in a self-supporting polymer matrix, as described in International Application PCT/FR2008/051160 filed on 25 Jun. 2008 or in European Patent Application EP 1 786 883.
If the two electroactive materials are electrochromic materials, these may be identical or different. If one of the electroactive materials is electrochromic and the other is not, the latter will act as counter-electrode not participating in the coloring and bleaching processes of the system.
Assuming that the compound (ea1+) is electrochromic (for example being 1,1′-diethyl-4,4′-bipyridinium diperchlorate) and assuming that the compound (ea2) is electrochromic (for example being 5,10-dihydro-5,10-dimethylphenazine) or nonelectrochromic (for example being a ferrocene), the redox reactions that are set up under the action of the electrical current are the following:
ea
1
+
+e
−
→ea
1
ea
2
≡ea
2
+
+e
−
In such known devices and in accordance with a first prior art, as illustrated by
In this case, and for small glazing, such as rearview mirrors for example, the transition from the bleached state to the bleached state may take place uniformly.
In contrast, for glazing larger in size, such as architectural glazing, the transition from the bleached state to the bleached state takes place with a curtain effect consisting in having coloration that starts at only one or at both of the two current leads and then propagates through the rest of the glazing. This is illustrated schematically in
Moreover, for such large glazing, during the coloration step, but also when the colored state is at a maximum, the absorption of the glazing will be greater with one or the two current leads than that away from these current leads.
In accordance with a second prior art, represented by French Patent Application filed on May 12, 2008 under the number 08/58289 in the name of the Applicant company and having as title “Dispositif électrocommandable présentant un acheminement amélioré des charges électriques en milieu électro-actif [Electrically controllable device having improved flow of electrical charges in an electroactive medium]”, the conductive strips used as current leads are applied to the entire perimeter of the conductive layers, which face or substantially face one another so as to avoid any color segregation when the electrochromic device is kept for a long time in the colored state.
As in the previous case, the transition from the bleached state to the colored state may take place uniformly for small glazing.
In contrast, for glazing of large size, the transition from the bleached state to the colored state will be accompanied by a halo effect in which the coloration starts at the current leads. This is what is illustrated in
Here again, for such large glazing, during the coloration step, but also when the colored state is at a maximum, the absorption of the glazing will be larger at the periphery of the glazing, at the place where the current leads are, than at the center of this glazing.
The applicant company has therefore sought an effective means for eliminating the curtain or halo effects during the electrochromic glazing coloration process and for ensuring uniform absorption over the entire surface of electrochromic glazing both in the colored and bleached states, and during the coloration and bleaching steps, irrespective of the size of this glazing.
These objectives have been achieved according to the present invention by the use of conductive layers that are specifically manufactured in order to limit the ohmic drop at the electrodes of electrochromic glazing. The results of the present invention may be seen by looking at
The subject of the present invention is therefore an electrically controllable device having variable optical/energy properties, comprising the multilayer stack as defined right at the beginning of this description, characterized in that each of the layers TCC1 and TCC2 is chosen to have a resistance R□ per unit area enabling it to have an equipotential surface in coloring mode and bleaching mode, each of the layers TCC1 and TCC2 having a variable resistance R□ that gradually decreases from the periphery toward the interior of the electrically controllable device by choosing R□ at the center of the glazing, in the zone or zones furthest away from the current leads, so that the ohmic drop over the central surface of the substrates of the glazing, in the zone or zones furthest away from the current leads, is at most equal to 5% of the voltage applied across the terminals of the device.
This enables a uniform current distribution to be obtained, those parts of the TCCs that have lower resistivity acting as electron wells. The result obtained is that the halo phenomenon is avoided.
This is because the surface voltage VP at a point P on one of the conductive layers is defined by the equation:
V
P
=V
applied
−iR
in which:
R=ρL/A=ρL/(Wt)=R□L/W
where:
Preferably, the two facing layers TCC1 and TCC2 are identical.
The layers TCC1 and TCC2 may have a variable resistance R□ that gradually decreases in a progressive manner along a gradient.
The grid or microgrid may be made of a metal, such as aluminum.
The layers TCC1 and TCC2 may have a variable resistance R□ that gradually decreases in zones.
Advantageously, a conductive layer TCC1 or TCC2 of variable resistance R has a resistance which goes from 20Ω/□ or more on the periphery to 5Ω/□ or less at the center of the layer.
A layer TCC1 or TCC2 may take the form of a continuous layer or the form of a grid or a microgrid, or else the form of grids or of a microgrid which is coated with a continuous layer.
A layer TCC1 or TCC2 having a variable resistance R may be obtained:
French Patent Application FR 2 875 669 describes such arrays of conductive and/or insulating features.
Thus, as indicated in the above application, it is possible to create an array of insulating or weakly conductive features in the conductive layer (TCC1, TCC2) and to form an array with conductive features by filling holes formed in the conductive layer (TCC1, TCC2) with a material more conductive than that of the latter, by producing the conductive layer (TCC1, TCC2) with local overthicknesses forming the array of features, said overthicknesses being sufficient to obtain the desired characteristics, or else by producing portions of a more conductive second layer (TCC1, TCC2), this second layer being deposited for example by sputtering on the layer covered beforehand with a mask. The conductive features are especially silver dots.
The electronically conductive layers TCC1 and TCC2 are especially metal layers, such as silver, gold, platinum or copper layers; transparent conductive oxide (TCO) layers, such as tin-doped indium oxide (In2O3:Sn or ITO), antimony-doped indium oxide (In2O3:Sb), fluorine-doped tin oxide (SnO2:F) and aluminum-doped zinc oxide (ZnO:Al) layers; or multilayers of the TCO/metal/TCO type, the TCO and the metal being in particular chosen from those listed above; or multilayers of the NiCr/metal/NiCr type, the metal being especially chosen from those listed above.
The layers TCC1 and TCC2 may be each connected to a current lead formed by a conductive strip applied to the associated layer TCC1 or TCC2, it being possible for the conductive strip to be a metal, an alloy or an electrically conductive composite which is deposited directly on the substrate covered with its conductive layer or on a spacer separating the two spacer substrates using, for example, a vacuum deposition technique or a screen printing technique with a metal paste, or else which is soldered to the substrate covered with its conductive layer or on a spacer separating the two substrates or else which is bonded using an electrically conductive adhesive, it being possible for the conductive strip applied to a substrate to be continuous or to have discontinuous regions that are connected together and for it to be applied on all or part of each substrate.
The current leads in particular consist of continuous conductive strips applied to the layers TCC1 and TCC2 and placed over the entire perimeter or substantially over the entire perimeter of said conductive layers (TCC1 and TCC2).
The substrates having a glass function may be chosen from glass and transparent polymers, such as polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polyethylene naphthoate (PEN) and cyclosporine copolymers (COCs).
Moreover, lying between a substrate having a glass function, in particular a plastic substrate, and a layer TCC1 or TCC2 may be a layer or a multilayer stack, this layer or stack being chosen independently from inorganic, organic and organic-inorganic hybrid layers and having been deposited on the substrate before the associated layer TCC1 or TCC2 has been deposited, in particular so as to improve the adhesion of the TCC1 or TCC2 to the substrate or to provide an additional function, such as gas impermeability and moisture impermeability. As an example of such an intermediate layer, mention may be made of an Si3N4 or SiO2 layer, which acts in particular as a moisture and oxygen barrier.
In accordance with a first variant, the electroactive system (EA) may comprise a self-supporting polymer matrix into which the electroactive organic compound or compounds (ea1+ and ea2) and the ionic charges have been inserted, said polymer matrix containing within it a liquid (L) dissolving said ionic charges but not dissolving said self-supporting polymer matrix, said matrix being chosen so as to provide a percolation path for the ionic charges in order to allow said electroactive organic compounds (ea1+ and ea2) to undergo said oxidation and reduction reactions, the ionic charges being carried by at least one of said electroactive organic compounds (ea1+ and ea2) and/or reduced and oxidized species that are respectively associated therewith (ea1 and ea2+), and/or by at least one ionic salt and/or at least one acid dissolved in said liquid (L) and/or by said self-supporting polymer matrix, and the liquid (L) being formed by a solvent or a solvent mixture and/or by at least one ionic liquid or a molten salt at room temperature, said ionic liquid or molten salt or said ionic liquids or molten salts then constituting a liquid (L) carrying ionic charges, which represent some or all of the ionic charges of said electroactive system.
According to a second variant, the electroactive system may comprise a solution or a gel containing the electroactive organic compounds (ea1+ and ea2).
The electroactive organic compound or compounds (ea1+) may be chosen from bipyridiniums or viologens, such as 1,1′-diethyl-4,4′-bipyridinium diperchlorate, pyraziniums, pyrimidiniums, quinoxaliniums, pyryliums, pyridiniums, tetrazoliums, verdazyls, quinones, quinodimethanes, tricyanovinylbenzenes, tetracyanoethylene, polysulfides and disulfides, and also all the electroactive polymeric derivatives of the electroactive compounds mentioned above, and the electroactive organic compound or compounds (ea2) is or are chosen from metallocenes, such as cobaltocenes and ferrocenes, N,N,N′,N′-tetramethylphenylenediamine (TMPD), phenothiazines, such as phenothiazine and dihydrophenazines such as 5,10-dihydro-5,10-dimethylphenazine, reduced methyl-phenothiazone (MPT), Bernthsen's methylene violet (MV), verdazyls and all electroactive polymeric derivatives of the abovementioned electroactive compounds.
The ionic salt or salts may be chosen from lithium perchlorate, trifluoromethanesulfonate or triflate salts, trifluoromethanesulfonylimide salts and ammonium salts; the acid or acids are chosen from sulfuric acid (H2SO4), triflic acid (CF3SO3H), phosphoric acid (H3PO4) and polyphosphoric acid (Hn+2PnO3n+1); the solvent or solvents may be chosen from dimethylsulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, propylene carbonate, ethylene carbonate, N-methyl-2-pyrrolidone (1-methyl-2-pyrrolidinone), γ-butyrolactone, ethylene glycols, alcohols, ketones, nitriles and water; and the ionic liquid or liquids may be chosen from imidazolium salts, such as 1-ethyl-3-methylimidazolium tetrafluoroborate (emim-BF4), 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (emim-CF3SO3), 1-ethyl-3-methylimidazolium bis(trifluoromethyl sulfonyl)imide (emim-N(CF3SO2)2 or emim-TSFI) and 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (bmim-N(CF3SO2)2 or bmim-TSFI).
The self-supporting polymer matrix may be formed by at least one polymer layer in which said liquid has penetrated to the core.
The polymer constituting at least one layer may be a homopolymer or copolymer taking the form of a nonporous film but capable of swelling in said liquid, or taking the form of a porous film, said porous film being possibly capable of swelling in the liquid containing ionic charges, and the porosity of said film after swelling is chosen so as to allow the ionic charges to percolate through the thickness of the liquid-impregnated film.
The polymeric material constituting at least one layer may also be chosen from:
The polymer matrix may be formed by a film based on a homopolymer or copolymer containing ionic charges, able by itself to give a film essentially capable of ensuring that the desired rate of percolation for the electroactive system or a higher rate of percolation than that is obtained, and on a homopolymer or copolymer, which may or may not contain ionic charges, able by itself to give a film not necessarily ensuring that the desired rate of percolation is obtained but essentially capable of providing mechanical strength, the contents of each of these two homopolymers or copolymers being regulated so as to ensure that both the desired rate of percolation and the mechanical strength of the resulting self-supporting organic active medium are obtained.
The polymer or polymers of the polymer matrix not containing ionic charges may be chosen from the following: copolymers of ethylene, vinyl acetate and optionally at least one other comonomer, such as ethylene-vinyl acetate (EVA) copolymers; polyurethane (PU); polyvinyl butyral (PVB); polyimides (PI); polyamides (PA); polystyrene (PS); polyvinylidene fluoride (PVDF); polyetheretherketone (PEEK); polyethylene oxide (PEO); epichlorohydrin copolymers; and polymethyl methacrylate (PMMA); and
the polymer or polymers of the polymer matrix containing ionic charges, or polyelectrolytes, may be chosen from sulfonated polymers that have undergone an exchange of the H+ ions of the SO3H groups by the ions of the desired ionic charges, this ion exchange taking place before and/or simultaneously with the swelling of the polyelectrolyte in the liquid containing ionic charges, the sulfonated polymers being especially chosen from sulfonated tetrafluoroethylene copolymers, sulfonated polystyrenes (PSS), sulfonated polystyrene copolymers, poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPS), sulfonated polyetheretherketones (PEEK) and sulfonated polyimides.
The electrically controllable device of the present invention may also possess current leads at the respective layers TCC1 and TCC2 consisting of conductive strips applied to the layers TCC1 and TCC2. The conductive strip may be a metal, an alloy or an electrically conductive composite which is deposited directly on the substrates covered with a conductive layer or on the spacers using, for example, a vacuum deposition technique or a screen printing technique with a metal paste, or else which is soldered to the substrates covered with a conductive layer or on the spacers or else which is bonded using an electrically conductive adhesive. The conductive strips of each substrate may be continuous or discontinuous and connected together and may be applied to all or part of each substrate. According to a preferred embodiment of the invention, the current leads are formed from continuous conductive strips applied to the layers TCC1 and TCC2 and placed along the entire perimeter or substantially along the entire perimeter of said conductive layers (TCC1 and TCC2).
The electrically controllable device of the present invention is especially configured to form: a motor vehicle roof, which is activatable autonomously, or a side window or rear window for a motor vehicle or a rearview mirror; a windshield or a portion of a windshield for a motor vehicle or for an airplane or for a ship; an automobile roof; an airplane window; a panel for displaying graphical and/or alpha-numeric information; interior or exterior architectural glazing; a skylight; a shop counter or display case; glazing for the protection of an object of the painting type; a computer antidazzle screen; glass furniture; a wall separating two rooms inside a building.
To better illustrate the subject of the present invention, two particular embodiments thereof will be described in greater detail below, with reference to the appended drawing.
In this drawing:
The current leads for the layers TCC1, TCC2 respectively are produced by shims 1, 2 respectively, each formed by an L-shaped metal strip, one of the branches of which is applied to the edge of the coated glass V1, V2 and the other branch of which is applied against that part of the layer TCC1, TCC2 extending beyond the “reservoir” part. The shims 1, 2 are applied along the upper border and along the lower border of the rearview mirror respectively.
In the following explanation, 1,1′-diethyl-4,4′-bipyridinium diperchlorate (electrochromic) is chosen as compound ea1+ and 5,10-dihydro-5,10-dimethylphenazine (electrochromic) or ferrocene (nonelectrochromic or counterelectrode not participating in the coloring process of the system) is chosen as compound ea2.
In an ideal system, where no voltage is applied to the device, the active medium containing the ea1+ and ea2 species is colorless and, when a voltage is applied, the ea1+ species are reduced to ea1 species, these being uniformly distributed in the vicinity of the surface of the electronically conductive layer connected to the negative pole of the power supply, i.e. connected to the cathode of the glazing, and, likewise, the ea2 species are oxidized to ea2+ species, these being uniformly distributed in the vicinity of the surface of the electronically conductive layer connected to the positive pole of the power supply, i.e. connected to the anode of the glazing, the panel then appearing with a uniform color corresponding to the uniform mixing of the ea1 and ea2+ species.
However, in reality it turns out that, when an electrical current is applied and when this current is cut off, a phase segregation phenomenon occurs between the pairs of species (ea1, ea1+) and (ea2, ea2+) and especially between the ea1 and ea2+ species. This phenomenon decreases over the course of time once the bleaching process has been started or during the coloration obtained after the poles of the power supply have been reversed, which phenomenon however may still remain for a very long time, or even still remain when a new command to change the state of the electrically controllable device is applied, so that, in this case, the desired uniform colors are never obtained, whether in the colored state or in the bleached state.
This segregation phenomenon is due to the preferential reduction of the ea1+ species to ea1 species toward the higher current density zone of the cathode and, conversely, due to the preferential oxidation of the ea2 species to ea2+ species toward the higher current density zone of the anode, these two higher current density zones being those of the shims.
Moreover, the segregation phenomenon is greater the larger the size of the panel of the electrically controllable device and, at the present time, prevents large electrically controllable devices, such as electrically controllable architectural glazing, from being commercially exploited.
Referring to
A conductive current lead strip is applied to each of the coated glass sheets, this strip having a length 1 along one border as in the case of the prior art shown in
The aforementioned thin strips are folded on themselves, each time through 90°, at the corners. They are located with regard to the spacer frame 3 by facing each other in the embodiment shown in
The assembly of the glazing unit and the encapsulation of the medium EA are carried out conventionally, the current lead strips having been soldered or bonded beforehand to the perimeter of the corresponding coated glass sheet.
The following examples illustrate the present invention without however limiting its scope. In these examples, the following abbreviations have been used:
The glass “K-glass®” used in the examples is a glass covered with an electroconductive SnO2:F layer (glass sold under this name by the company Pilkington).
The glass “VG40” used in the examples is a tinted glass having a light transmission TL of 54%, from the Venus Thermocontrol® range by Saint-Gobain Sekurit.
To produce the PVDF films, polyvinylidene fluoride powder manufactured by the company Arkema under the name “Kynarflex® 2821” was used.
In the Tables:
K-glass® plate with R□=20.5Ω/□;
Electroactive system: PVDF+ferrocene+1,1′-diethyl-4,4′-bipyridinium diperchlorate+lithium triflate+propylene carbonate;
K-glass® plate with R□=20.5Ω/□;
Current lead strip soldered to the K-glass® plate over the entire periphery of each K-glass® plate according to the configuration shown in
A self-supporting PVDF film was produced by mixing 6.5 g of PVDF powder with 13.0 g of dibutyl phthalate, 0.5 g of nanoporous silica and 25 g of acetone. The formulation was stirred for 2 hours and cast on a glass plate. After solvent evaporation, the PVDF film was removed from the glass plate under a stream of water. The film thus obtained had a thickness of about 200 μm.
An electroactive solution was prepared by mixing 0.17 g of ferrocene, 0.37 g of 1,1′-diethyl-4,4′-bipyridinium diperchlorate and 0.28 g of lithium triflate in 30 ml of propylene carbonate. The solution was stirred for 1 hour.
The approximately 200-micron thick PVDF film was immersed for 5 minutes in diethyl ether (to dissolve the dibutyl phthalate) and then for 5 minutes in the electroactive solution before being deposited on a K-glass® plate. A second K-glass® plate was deposited on the electrolyte-impregnated film, a PET frame was used as spacer around the electroactive medium, and clips were used to ensure good contact between the glass and the film.
The electrochromic device thus produced had an active surface of 22×23 cm2 area and its performance characteristics are given in Table 1 below:
Glass plate with an ITO layer having regions of differed R□: 20, 10 and 5Ω/□, as illustrated in
Electroactive system of Example 1;
Glass plate with an ITO layer having regions of differed R□: 20, 10 and 5Ω/□, as illustrated in
Current lead strip soldered to the K-glass® plate over the entire periphery of each K-glass® plate according to the configuration shown in
An ITO conductive layer was produced with a variable surface resistance by carrying out three ITO depositions on the same substrate by magnetron sputtering.
During the first deposition, the ITO was deposited over the entire surface of the substrate and the deposited thickness of 180 nm provided an R□˜20Ω/□.
During the second deposition, a PET mask was used to protect the substrate except for a central circle of 15 cm in diameter. The thickness deposited during this second deposition was 90 nm, enabling an R□˜10Ω/□ to be achieved at the center of the substrate.
During the third deposition, a PET mask was used to protect the substrate with the exception of a central circle of 6 cm in diameter. The thickness deposited during this third deposition was 240 nm, enabling an R□˜5Ω/□ to be achieved at the center of the substrate.
An electrochromic device having an active surface of 22×23 cm2 area was produced as described in Example 1, the performance characteristics of which are given in Table 2 below:
K-glass® plate with R□=20.5Ω/□;
Electroactive system: PVDF+5,10-dihydro-5,10-dimethylphenazine+1,1′-diethyl-4,4′-bipyridinium diperchlorate+lithium triflate+propylene carbonate;
K-glass® plate with R□=20.5Ω/□;
Current lead strip soldered to the K-glass® plate over the entire periphery of each K-glass® plate according to the configuration shown in
An electroactive solution was prepared by mixing 0.25 g of 5,10-dihydro-5,10-dimethylphenazine, 0.50 g of 1,1′-diethyl-4,4′-bipyridinium diperchlorate and 0.47 g of lithium triflate in 20 ml of propylene carbonate. The solution was stirred for 1 hour.
An electrochromic device was produced having an active surface of 22×23 cm2 area as described in Example 1, the performance characteristics of which are given in Table 3 below:
Glass plate with an ITO layer with R□ varying between 20, 10 and 5Ω/□ of Example 2;
Electroactive system of Example 2;
Glass plate with an ITO layer with R□ varying between 20, 10 and 5Ω/□, of Example 2;
Shims soldered to the entire perimeter of the coated glass plates;
Current lead strip soldered to the K-glass® plate over the entire periphery of each K-glass® plate according to
An electrochromic device having an active surface of 22×23 cm2 area was produced as described in Example 1, the performance characteristics of which are given in Table 4 below:
| Number | Date | Country | Kind |
|---|---|---|---|
| 0951309 | Mar 2009 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2010/052620 | 3/2/2010 | WO | 00 | 9/14/2011 |
