Patent Application
20080212160
The present invention relates to a method for supplying an electrically controllable device having variable optical and/or energy properties. It relates more particularly to devices using electrochromic systems, whether operating in transmission or in reflection.
Electrochromic systems have been very extensively studied. They are constructed on the following “five-layer” model: TC1/EC1/EL/EC2/TC2, where TC1 and TC2 are electronically conducting materials, EC1 and EC2 are electrochromic materials capable of reversibly and simultaneously inserting cations and electrons, and EL is an electrolyte material that is both an electronic insulator and an ionic conductor. The electronic conductors are connected to an external electrical supply and application of a suitable potential difference between the two electronic conductors causes the system to change color. Under the effect of the potential difference, the ions are ejected from one electrochromic material and inserted into the other electrochromic material, passing via the electrolyte material. The electrons are extracted from one electrochromic material, entering the other electrochromic material via the electronic conductors and the external supply circuit in order to counterbalance the charges and ensure electrical neutrality of the materials.
A modification in their oxidation state as a result of these charge insertions/ejections results in a modification in their optical and/or thermal properties (for example, in the case of tungsten oxide, a switch from a blue color to a colorless appearance and, in the case of iridium oxide, a switch from a yellowish color to a colorless appearance).
The electrochromic system is generally deposited on a transparent or nontransparent support, of organic or mineral nature, which then takes the name “substrate”. In certain cases, two substrates may be used: either each substrate possesses one part of the electrochromic system, and the complete system is obtained by joining the substrates together, or one substrate has the entire electrochromic system and the other is intended to protect the system.
The switching of the electrically controllable system consists of a complex electrochemical process defined by a charge transfer (electrical migration of charged species (ions and electrons) within a thin-film multilayer a few hundred nanometers in thickness) and of a mass transfer, due to the movement of the charged species in the multilayer.
Under the effect of the potential difference, the charge transfer within the electrically controllable system results in an electrochemical equilibrium corresponding to a colored state or a bleached state of the system, and therefore to certain optical properties characterized for example by the level of light transmission (generally expressed in %) achieved.
Now, electrically controllable system manufacturers have developed electrical supplies that deliver potential differences corresponding to operating points for which, on the one hand, optical optimization of the system—color homogeneity, switching speed, contrast—and, on the other hand, mechanical optimization—preservation of these functionalities after several coloring/bleaching cycles (i.e. durability)—are obtained.
Although these systems are entirely satisfactory, manufacturers have noticed that this optimization, both optical and mechanical, does not last over the course of time. For a given operating point, corresponding to a potential difference applied to the terminals of the electrically controllable system, there is a drift over time in the operating point (the optical performance is no longer obtained for this potential value).
Starting from the postulate that it is difficult (or almost impossible) to provide the electrically controllable systems with an optical measurement sensor (especially for measuring the percentage light transmission), the inventors have discovered, quite surprisingly, that it is possible to adapt or modify the operating point of the electrically controllable system, thus making it possible for it to guarantee the optimum performance over the course of time, while obviating any optical measurement.
The object of the present invention is therefore to alleviate the drawbacks of the prior supplies by proposing a novel design of electrically controllable system and a novel design of its method of supply that obviate any variations as a result of a drift in the operating point.
For this purpose, the electrically controllable system having variable optical/energy properties in transmission or reflection, comprising at least one carrier substrate provided with a multilayer allowing the migration of active species, especially an electrochromic multilayer comprising at least two active layers that are separated by at least one layer having an electrolyte function, said multilayer being placed between two electronic conductors connected respectively to current leads, namely lower and upper leads respectively (“lower” corresponding to the current lead closest to the carrier substrate, as opposed to the “upper” current lead, which is furthest from said substrate), is characterized in that the layer having an electrolyte function incorporates at least one hybrid layer based on a metal layer and on a passivation layer for passivating the same metal as that of the metal layer.
Thanks to this hybrid layer incorporated within the layer having an electrolyte function, it is possible to create, within the multilayer forming the electrically controllable system, a third electrode, called a reference electrode, suitable for determining the distribution of the potentials within the system.
In preferred embodiments of the invention, one or more of the following arrangements may optionally be furthermore employed:
According to another aspect, the subject of the invention is also a method of operating the electrically controllable system as described above.
For this purpose, the method for supplying an electrically controllable system having variable optical/energy properties, in transmission or reflection, comprising at least one carrier substrate provided with a multilayer allowing the migration of active species, especially an electrochromic multilayer comprising at least two active layers that are separated by at least one layer having an electrolyte function incorporating at least one hybrid layer based on a metal layer and on a passivation layer for passivating the same metal as that of the metal layer, the hybrid layer forming a reference electrode, said multilayer being placed between two electronic conductors connected respectively to current leads, namely lower and upper leads respectively (“lower” corresponding to the current lead closest to the carrier substrate, as opposed to the “upper” current lead, which is furthest from said substrate), is characterized in that:
In preferred embodiments of the invention, one or more of the following arrangements may optionally be furthermore employed:
The invention will be described in greater detail in conjunction with the appended figures in which:
In the appended drawings, certain elements may be shown on a larger or smaller scale than in reality, so as to make it easier to understand the figure.
The example illustrated by
The glass panes S1 and S2 are of the same size, with dimensions of 150 mm×150 mm.
The glass pane S1 shown in
The glass pane S1 is laminated to the glass pane S2 via a thermoplastic sheet f1 made of polyurethane (PU) 0.8 mm in thickness (it may be replaced with a sheet of ethylene/vinyl acetate (EVA) or polyvinyl butyral (PVB)).
The “all-solid-state” electrochromic thin-film multilayer comprises an active multilayer 3 placed between two electronically conducting materials, also called current collectors 2 and 4. The collector 2 is intended to be in contact with face 2.
The collectors 2 and 4 and the active multilayer 3 may either be of substantially the same dimensions and shape, or substantially different dimensions and shape, and it will be understood therefore that the path of the collectors 2 and 4 will be adapted according to the configuration. Moreover, the dimensions of the substrates, in particular of S1, may be essentially greater than those of 2, 4 and 3.
The collectors 2 and 4 are of the metallic type or of the TCO (Transparent Conductive Oxide) type, made of In2O3:Sn (ITO), SnO2:F or ZnO:Al, or a multilayer of the TCO/metal/TCO type, this metal being chosen in particular from silver, gold, platinum and copper. It may also be a multilayer of the NiCr/metal/NiCr type, the metal also being chosen in particular from silver, gold, platinum and copper.
Depending on the configurations, they may be omitted, and in this case current leads are directly in contact with the active multilayer 3.
The window 1 incorporates current leads 8, 9, which allow the active system to be controlled via an electrical supply. These current leads are of the type of those used for heated windows (namely shims, wires or the like).
One preferred embodiment of the collector 2 consists in depositing, on face 2, a 50 nm SiOC first layer surmounted by a 400 nm SnO2:F second layer (both layers preferably being deposited in succession by CVD on the float glass before cutting).
A second embodiment of the collector 2 consists in depositing, on face 2, a bilayer consisting of an approximately 20 nm SiO2-based first layer which may or may not be doped (especially doped with aluminum or boron) surmounted by an approximately 100 to 600 nm ITO second layer (both layers preferably being vacuum-deposited in succession by magnetron reactive sputtering in the presence of oxygen, optionally carried out hot).
Another embodiment of the collector 2 consists in depositing, on face 2, an approximately 100 to 600 nm monolayer consisting of ITO (a layer preferably vacuum-deposited by magnetron reactive sputtering in the presence of oxygen, optionally carried out hot).
The collector 4 is a 100 to 500 nm ITO layer again deposited by magnetron reactive sputtering on the active multilayer.
The active multilayer 3 shown in
According to a second embodiment, shown in
Irrespective of the embodiment of the electrically controllable system, and in particular the active multilayer shown in detail in
The active multilayer 3 may be incised over all or part of its periphery with grooves produced by mechanical means or by etching using laser radiation, optionally pulsed laser radiation, for the purpose of limiting peripheral electrical leakage, as described in French Application FR-2 781 084.
Moreover, the window shown in
A second peripheral seal is in contact with the edge of S1, the edge of S2 and face 4, so as to produce: a barrier; a means for fitting it into the vehicle; sealing between the inside and the outside; an esthetic function; and a means of incorporating the reinforcing elements.
In other embodiments, the “all-solid-state” active multilayer 3 may be replaced with other families of electrochromic materials of the polymer type.
Thus, for example, a first part formed from a 10 to 10,000 nm, preferably 50 to 500 nm, layer of electrochromic material, also called the active layer, made of poly(3,4-ethylenedioxythiophene)—as a variant it may be one of the derivatives of this polymer—is deposited by known liquid deposition techniques (spray coating, dip coating, spin coating or casting), or by electrodeposition, on a substrate coated with its current collector, it being possible for this current collector to be a lower conducting layer or an upper conducting layer forming the electronic conductor (the anode or the cathode), optionally provided with wires or the like. Whatever the polymer constituting this active layer, this polymer is particularly stable, especially to UV, and operates by insertion/ejection of lithium ions (Li+) or alternatively of H30 ions.
A second part acting as electrolyte, and formed from a layer with a thickness of between 50 nm and 2000 nm, and preferably between 50 nm and 1000 nm, is deposited by a known liquid deposition technique (spray coating, dip coating, spin coating or casting) between the first and third parts on the first part or else by injection. This second part is based on a polyoxyalkylene, especially polyoxyethylene. It may be combined with a layer of mineral-type electrolyte, for example based on hydrated tantalum oxide, zirconium oxide or silicon oxide.
This second electrolyte part deposited on the active layer of electrochromic material, itself supported by the glass or similar substrate, is then coated with a third part, the constitution of which is similar to the first part, namely this third part is made up of a substrate coated with a current collector (conducting wires, or conducting wires plus conducting layer, or only conducting layer), this current collector itself being covered with an active layer.
On the basis of this hybrid (polymer/mineral) electrochromic multilayer, it is proposed to incorporate the reference electrode described above within the mineral-type electrolyte layer.
This example corresponds to a window operating by proton transfer. It consists of a first glass substrate 1, made of 4 mm soda-lime-silica glass, followed in succession by:
In this example, there is therefore a bilayer electrolyte based on a polymer normally used in this type of glazing, which is “lined” with a layer of hydrated tantalum oxide that is sufficiently conducting not to impair proton transfer via the polymer and that protects the counterelectrode made of anodic electrochromic material from direct contact with the latter, the intrinsic acidity of which would be prejudicial thereto.
Instead of the hydrated Ta2O5 layer, a layer of the hydrated Sb2O5 or TaWOx type may be used.
It is also possible to provide a three-layer electrolyte, with two hydrated oxide layers, either with one of them on each side of the polymer layer, or with the two layers superposed one on the other on the side facing the layer of anodic electrochromic material.
The electrically controllable structure as described above with its reference electrode permits an innovative operation mode based on a comparison of the operation of the system at instant t with its operation relative to a preestablished knowledge model.
The first step therefore consists in establishing a database, namely a knowledge model of the electrically controllable system.
A supply mode is applied between the current leads of the electrically controllable system. Conventionally, this is a voltage source or a current source or a charge source.
To give an example, a first voltage level denoted by V1 is therefore applied. For this voltage level V1, a characteristic quantity of the system is recorded by appropriate means. This may be an optical property such as for example a light transmission level.
A light transmission level is therefore associated with this voltage level V1.
In parallel with this voltage level V1, the voltage between the reference electrode and each of the current leads is recorded, this being associated with the lower electronic conductor and upper electronic conductor respectively.
For any one light transmission level there are therefore three voltage levels (between the current leads, and between the reference electrode and each of the current leads).
These four data items are stored in a table.
Next, the voltage level is incremented between a minimum value and a maximum value, and for each of these voltage levels the entire database characteristic of the operating points of the electrically controllable system is constructed.
The actual operation phase consists in comparing the voltage levels obtained at an instant t across the terminals of the current leads and the reference electrode with the operating values of the knowledge model.
One operating mode may be the following:
If it is necessary to modify the level of the characteristic quantity, the light transmission level for example to be modified the voltage level applied across the terminals of the current leads.
At this instant t2, the level Vmes2 at the reference electrode and the current lead identical to that used for Vmes1 is recorded.
Vmes1 and Vmes2 are then compared and, depending on the difference, the level of the voltage applied between the current leads is readjusted so that the potential difference between one of the current leads and the reference electrode is equal to a value selected from a reference table.
Given below is a table of voltage levels between, on the one hand, the two current leads (namely V1, which varies between V1min and V1max) and, on the other hand, voltage levels measured between one of the current leads and the reference electrode, Vmes1. Each measurement has been normalized between 0 and 100, namely 100 corresponds to V1max and 0 corresponds to V1min. The Vmes1 measurements have also been normalized between 0 and 100 by the extreme values of Vmes1.
As can be seen in the graph of
The electrically controllable system as described may be incorporated within a glazing assembly having in particular a variable light and/or energy transmission and/or reflection, this glazing assembly consisting of at least one substrate in which at least one part of the substrate is transparent or partially transparent, made of glass or plastic, preferably mounted as multiple and/or laminated glazing, or as double glazing. It is also possible to combine this glazing assembly with at least one other layer suitable for providing an additional functionality (solar control, low emissivity, hydrophobicity, hydrophilicity, antireflection).
These glazing assemblies are used as architectural glazing, automotive glazing, windows for industrial or rail, sea or air mass-transit vehicles, rear-view mirrors, or other mirrors.
| Number | Date | Country | Kind |
|---|---|---|---|
| 05500563 | Mar 2005 | FR | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/FR06/50179 | 3/1/2006 | WO | 00 | 1/31/2008 |
