FR3148023A1 - Transparent substrate with a functional stack of thin layers - Google Patents

Abstract

Transparent substrate (10) provided with a functional stack (14) of thin layers on at least one of its faces (11), said functional stack (14) comprising, starting from the substrate (10), at least one metallic functional layer (140) placed between two dielectric modules (120,160) of thin layers, and in which at least one of the dielectric modules (120,160) of thin layers comprises a layer (120a,160a) of tungsten oxide, and the tungsten oxide optionally comprises at least one doping element selected from the chemical elements of group 1 according to the IUPAC nomenclature.

Description

Transparent substrate with a functional stack of thin layers

The invention relates to a transparent glass substrate provided with a functional stack of thin layers with several metallic functional layers.

Technical background

Functional stacks of thin layers are commonly used to provide thermal insulation and/or solar protection functions to glazing. These glazings can be used in buildings or vehicles. Their primary interest is that they reduce the air conditioning effort by avoiding excessive overheating (so-called "solar control" glazing) and/or by reducing the amount of energy dissipated to the outside (so-called "low-emissive" glazing).

A particularly used type of functional stack of thin layers comprises a metallic functional layer, in particular based on silver, allowing the reflection of part of the electromagnetic radiation, in particular infrared radiation.

The metallic functional layer is generally arranged between two dielectric assemblies, also called dielectric modules, in order to neutralize the optical effects of reflection and refraction in the visible range. These dielectric modules may comprise one or more thin dielectric layers of the nitride type, for example silicon or aluminum nitride, and/or of the oxide type, for example silicon, zinc, tin oxide.

Solar control functions are sought for glazings likely to be exposed to high levels of sunlight. The ability of a glazing to limit the amount of light energy transmitted is defined by the solar factor, g, which is the ratio of the total energy transmitted through the glazed surface or glazing to the interior to the incident solar energy. The lower the value of the solar factor, g, the better the protection against solar radiation.

JP H0812378 A [NISSAN MOTOR] 16.01.1996 describes a “solar control” functional stack comprising a tungsten oxide layer arranged between two dielectric layers. The stack makes it possible to reduce the surface electrical resistance and to increase the transparency to radio waves compared to stacks comprising a metallic functional layer, in particular based on silver.

JP 2010180449 A [SUMITOMO METAL MINING CO [JP]] 2010-08-19 discloses a tungsten oxide-based layer deposited by sputtering using a tungsten oxide target comprising chemical elements selected from hydrogen, alkali, alkaline earth and rare earth. The layer has a “solar control” function due to its strong absorption of near-infrared radiation.

EP 3686312 A1 [SUMITOMO METAL MINING CO [JP]] 29.07.2020 describes a layer based on cesium-doped tungsten oxide, and a method of depositing such a layer by sputtering. The layer has transparency to radio waves and a “solar control” function thanks, in particular, to its strong absorption of infrared radiation.

is a schematic representation of a first embodiment of the first aspect of the invention;
is a representation of the evolution of the optical extinction coefficient as a function of the wavelength W, in nanometers, of an example with a layer of cesium-doped tungsten oxide and of an example with a layer of sub-stoichiometric and pure tungsten oxide;
is a representation of the evolution of the optical refractive index as a function of the wavelength W, in nanometers, of an example with a layer of cesium-doped tungsten oxide and of an example with a layer of sub-stoichiometric and pure tungsten oxide;
is a schematic representation of a first embodiment of glazing according to the second aspect of the invention;
is a schematic representation of a second embodiment of glazing according to the second aspect of the invention;
is a graphical representation of selectivity as a function of light transmission for a CE counterexample, an E1 example and an E2 example;
is a graphical representation of selectivity as a function of light transmission for the CE counterexample, an E13' example, an E13''' example, and the E1 example;
is a graphical representation of selectivity as a function of light transmission for the CE counterexample, the E13' example, an E15' example, an E16' example, and the E1 example; and
is a graphical representation of selectivity versus light transmission for the CE counterexample, an E24' example, an E25' example, an E26' example, and the E2 example.

Detailed description of embodiments

It uses the following definitions and conventions.

The term “above” or “below” respectively, qualifying the position of a layer or set of layers and defined relative to the position of another layer or set, means that said layer or set of layers is closer to, or further away from, the substrate. These two terms, “above” and “below”, do not mean that the layer or set of layers that they qualify and the other layer or set in relation to which they are defined are in contact. They do not exclude the presence of other intermediate layers between these two layers. The expression “in contact” is explicitly used to indicate that no other layer is arranged between them.

Without any precision or qualification, the term "thickness" used for a layer corresponds to the physical, real or geometric thickness, e, of said layer. It is expressed in nanometers.

The expression “dielectric module” designates one or more layers in contact with each other forming a set of globally dielectric layers, that is to say that it does not have the functions of a metallic functional layer. If the dielectric module comprises several layers, these may themselves be dielectric. The physical thickness, real or geometric, of a dielectric module of layers corresponds to the sum of the physical thicknesses, real or geometric, of each of the layers that constitute it.

In the present description, the expressions "a layer of" or "a layer based on", used to qualify a material or a layer as to what it contains, are used equivalently. They mean that the mass fraction of the constituent that it comprises is at least 50%, in particular at least 70%, preferably at least 90%. In particular, the presence of minority or doping elements is not excluded.

By the term "transparent", used to describe a substrate, it is meant that the substrate is preferably colorless, non-opaque and non-translucent in order to minimize light absorption and thus maintain maximum light transmission in the visible electromagnetic spectrum.

The luminous transmission, TL, in the visible spectrum, the solar factor, g, and the selectivity, s, the internal reflection, Rint, and the external reflection, Rext, in the visible spectrum, as well as their methods of measurement and/or calculation are defined in the standards EN 410, ISO 9050 and ISO 10292.

According to the IUPAC nomenclature, group 1 of chemical elements includes hydrogen and the alkali elements, i.e. lithium, sodium, potassium, rubidium, cesium and francium.

By the expressions "optical refractive index" and "optical extinction coefficient" is meant the optical refractive index, n, and optical extinction coefficient, k, as defined in the technical field, in particular according to the Forouhi & Bloomer model described in the work Forouhi & Bloomer, Handbook of Optical Constants of Solids II, Palik, E.D. (ed.), Academic Press, 1991, Chapter 7.

According to a first aspect of the invention, with reference to the , a transparent glass substrate 10 is provided, provided with a functional stack 14 of thin layers on at least one of its faces 11, said functional stack 14 comprising, starting from the substrate 10: at least two metallic functional layers 140, 180 each placed between two dielectric modules 120, 160, 200 of thin layers, and in which at least one of the dielectric modules 120, 160, 200 of thin layers comprises a layer of tungsten oxide 120a, 160a, 200a, and the tungsten oxide optionally comprises at least one doping element selected from the chemical elements of group 1 according to the IUPAC nomenclature.

The tungsten oxide of the tungsten oxide layer(s) 120a, 160a, 200a may be pure substoichiometric tungsten oxide, WO _x , with x preferably between 2.55 and 2.98, or even between 2.6 and 2.95. A value of x between 2.98 and 3.02 will be considered as generating a pure stoichiometric tungsten oxide, WO ₃ .

Surprisingly, a tungsten oxide layer of pure substoichiometric tungsten oxide, WO _x , exhibits unexpected optical characteristics, particularly in terms of the evolution of the optical extinction coefficient and refractive index as a function of the wavelength of the electromagnetic radiation. These features, combined with the presence of several metallic functional layers, have a synergistic effect on increasing the selectivity.

Surprisingly, a tungsten oxide layer comprising a doping element selected from the group 1 elements according to the IUPAC nomenclature exhibits unexpected optical characteristics, particularly in terms of the evolution of the optical extinction coefficient and refractive index as a function of the wavelength of the electromagnetic radiation. These characteristics, combined with the presence of several metallic functional layers, have a synergistic effect on increasing selectivity.

As illustrative and explanatory examples, to which however the present invention should not be considered as inextricably linked, the evolutions of the optical extinction coefficient, k, and of the optical refractive index, n, are shown in the And respectively, on the one hand for a layer C1 of cesium-doped tungsten oxide and on the other hand for a layer C2 of pure substoichiometric tungsten oxide, WO _x , these layers being deposited by cathodic sputtering on a soda-lime-silica glass substrate according to two different deposition conditions.

On these And , layers C1 and C2 were deposited on a soda-lime-silica glass substrate on which a first silicon nitride-based layer with a thickness of approximately 5 nm had been previously deposited. They were then covered with a second silicon nitride-based layer with a thickness of approximately 5 nm. In other words, each layer C1 and C2 is encapsulated between two silicon nitride-based layers.

The encapsulation of layers C1 and C2 by two layers based on silicon nitride serves to prevent the degradation of layers C1 and C2 from excessive oxidation and/or excessive diffusion of oxygen into their structure. Instead of silicon nitride, it is possible to use any other suitable type of nitride such as, for example, zirconium nitride.

The C1 layer was deposited under an atmosphere comprising 20% dioxygen at a pressure of 4 mTorr. The resulting stack comprising the C1 layer was annealed at 650 °C for 10 min after deposition. The molar ratio of cesium to tungsten is approximately 0.05-0.06.

The C2 layer was deposited from a tungsten metal target, under an atmosphere comprising 60% dioxygen and at a pressure of 12 mTorr. The resulting stack comprising the C2 layer was annealed at 650 °C for 10 min after deposition. The C2 layer is thus a layer of pure substoichiometric tungsten oxide, WO _x , with an x of approximately 2.9.

The extinction coefficient and refractive index were calculated by modeling from experimental measurements. Measurements were obtained using a Perkin Elmer Lambda 900 spectrophotometer and a VASE M-2000XI J.A. Wollam ellipsometer.

In reference to the , regardless of the C1 or C2 layer, the extinction coefficient decreases monotonically from a value below 1 at 300 nm to a minimum level below 0.1 for C1 and below 0.05 for C2 between about 400 nm and 550 nm, then increases monotonically to a value above 1.2 at about 1200 nm for C1 and a value above 0.5 at about 1200 nm for C2. The C1 and C2 layers have strong absorption in the near infrared and some transparency in the visible region of the electromagnetic spectrum. The C2 layer has absorption in the visible light spectrum and in the near infrared that are lower than those of the C1 layer.

In reference to the , for the C1 layer, the optical refractive index decreases monotonically from a value close to 3 at 300 nm to reach a minimum level of less than 1.8, or even 1.6 between about 800 nm and 1100 nm, then increases monotonically to reach a value greater than 1.8, or even 2 around 1300-1400 nm. For the C2 layer, the optical refractive index decreases monotonically from a value close to 3 at 300 nm to reach a small level at a value close to 1.6 between about 900 nm and 1100 nm, then decreases monotonically again to reach a value of about 1.45 around 1300 nm.

According to other preferred embodiments, the optical refractive index of the tungsten oxide layer 120a, 160a, 200a decreases monotonically with wavelength from a maximum value greater than 2.4 at 350 nm to a minimum value between 600 nm and 900 nm such that the difference between the maximum value and the minimum value is greater than 0.8, preferably 1.0, or even 1.4.

In other words, the value of the optical refractive index decreases monotonically by at least 0.8, preferably by at least 1.0, or even at least 1.4 between a maximum value greater than 2.4 at 350 nm and a minimum value between 600 nm and 900 nm. By way of example, the optical refractive index value may decrease monotonically by at least 0.8, preferably by at least 1.0, or even at least 1.4 between a maximum value greater than 2.4 at 350 nm and a minimum value less than 2.3 between 600 nm and 900 nm, in particular between 800 nm and 900 nm.

Although not particularly required to achieve the effects of the present invention, these optical refractive index values may nevertheless be advantageous in terms of meeting color specifications for applications in the building and construction markets. In particular, they allow neutral colors to be obtained.

According to certain additional preferred embodiments, the optical extinction coefficient of the tungsten oxide layer 120a, 160a, 200a may be less than 0.2, or even 0.1 at 500 nm and less than 2, or even 1.5 at 1200 nm. The selectivity can thus be favorably further increased.

The optical extinction coefficient and the optical diffraction index may vary if one or more doping elements are included in the tungsten oxide layer and according to the nature and quantity of the doping element(s) selected from the elements of group 1 according to the IUPAC nomenclature. In particular, they may exhibit behaviors different from what has been described previously in the context of the illustrative and explanatory examples of the And . However, it is currently difficult to establish a general behavior law for the optical extinction coefficient and the refractive index according to the nature and/or quantity of the doping element(s).

According to certain particular embodiments, the tungsten oxide layer does not comprise any doping element and is made of pure substoichiometric tungsten oxide, WOx, with x preferably between 2.55 and 2.98.

According to certain particular embodiments, the tungsten oxide layer comprises the doping element X or the doping elements X1, X2,… in a proportion such that the molar ratio, X/W of said element on the tungsten, W, or the sum of the molar ratios of each element on the tungsten (X1+X2+…)/W is between 0.01 and 0.4, preferably between 0.01 and 0.2, or even between 0.01 and 0.1. It has been found that these molar ratio values can advantageously make it possible to obtain the optical extinction coefficient and refractive index values described in the preceding embodiments while limiting the quantity of doping elements. In addition, a saving on the exploitation of mineral resources for the doping elements can possibly result therefrom, as well as a reduction in costs.

In some embodiments, the tungsten oxide layer comprises at least one doping element selected from hydrogen, lithium, sodium, potassium and cesium. Among the group 1 elements, these particular elements can provide the most optimal optical extinction coefficient and refractive index values for the desired technical effects.

In particularly preferred embodiments, the tungsten oxide layer comprises cesium as a doping element, and the molar ratio of cesium to tungsten is between 0.01 and 0.2, preferably between 0.01 and 0.1. These embodiments provide the best performance in terms of increased selectivity, preservation of neutral colors, and cost savings.

What is most important in the context of the invention is that the absorption in the visible range of the material of the tungsten oxide layer(s) is as low as possible in the visible range (wavelength from 380 to 780 nm) in order to maximize the gain in selectivity.

The substrate 10, transparent, may preferably be flat and may be of organic or inorganic nature, rigid or flexible. In particular, it may be a mineral glass, for example a soda-lime-silica glass.

Examples of organic substrates that can be advantageously used for implementing the invention may be polymeric materials such as polyethylenes, polyesters, polyacrylates, polycarbonates, polyurethanes, polyamides. These polymers may be fluorinated polymers.

Examples of mineral substrates that can be advantageously implemented in the invention may be mineral or glass-ceramic glass sheets. The glass may preferably be a soda-lime-silica, borosilicate, aluminosilicate or alumino-borosilicate type glass. According to a preferred embodiment of the invention, the substrate 10 is a soda-lime-silica mineral glass sheet.

The presence of the tungsten oxide layer 120a, 160a, 200a in each dielectric module 120, 160, 200 allows the greatest reductions in solar factor and the greatest increases in light transmission.

According to certain advantageous embodiments, the physical thickness of the tungsten oxide layer(s) 120a, 160a, 200a may be between 2 nm and 50 nm, in particular between 5 nm and 30 nm, preferably between 5 nm and 20 nm. These thickness ranges are sufficient to obtain the remarkable advantages of the first aspect of the invention.

There illustrates a structure of a stack 14 with several functional layers according to the invention deposited on a face 11 of a transparent glass substrate 10. This diagram illustrates the positions of different layers relative to each other when these layers are present.

In this structure, the functional layers 140, 180 are in particular based on silver or a metal alloy containing silver, and are each arranged between two antireflection modules: the underlying antireflection module 120 located below the first functional layer 140 in the direction of the substrate 10 and the intermediate antireflection module 160 arranged above the first functional layer 140 opposite the substrate 10 and under the second functional layer 180. An overlying antireflection module 200 is arranged above the second functional layer 180 opposite the substrate 10.

These anti-reflective modules 120, 160, 200 each comprise at least one dielectric layer 124, 126, 129; 162, 164, 166, 168, 169; 202, 203, 204, 206.

A terminal protective layer 300, furthest from face 11, can complete the stack.

For the illustrated two-layer functional stack structure, the first functional layer 140 is located indirectly on the underlying anti-reflective module 120 and indirectly under the intermediate anti-reflective module 160: there is an under-blocking layer 130 located between the underlying anti-reflective module 120 and the first functional layer 140 and an over-blocking layer 150 located between the first functional layer 140 and the intermediate anti-reflective module 160.

For the illustrated two-functional layer stack structure, the second functional layer 180 is located indirectly on the underlying intermediate anti-reflective module 160 and indirectly below the anti-reflective module 200: there is an under-blocking layer 170 located between the underlying anti-reflective module 160 and the second functional layer 180 and an over-blocking layer 190 located between the second functional layer 180 and the anti-reflective module 200.

Each metal functional layer 140, 180 has the function of reflecting infrared radiation and/or a portion of solar radiation. It may be of any suitable metal, for example gold-based or silver-based. The thickness of each metal functional layer 140, 180 may typically be between 2 nm and 25 nm, preferably between 10 nm and 20 nm.

According to preferred embodiments, each metal functional layer 140, 180 is a silver-based layer.

The dielectric modules may comprise one or more layers of oxides and/or nitrides of metallic elements and/or metal alloys, such as, for example, zinc oxide, mixed zinc and tin oxide, silicon nitride, silicon oxide, zirconium nitride, titanium oxide, tin oxide, and silicon oxynitride.

The methods of depositing thin layers on substrates, in particular glass substrates, are methods well known in the industry. For example, the deposition of a stack of thin layers on a glass substrate is carried out by successive deposits of each thin layer of said stack by passing the glass substrate through a succession of deposition cells adapted to deposit a given thin layer.

Deposition cells can use deposition methods such as magnetic field-assisted sputtering (also called magnetron sputtering), ion beam-assisted deposition (IBAD), evaporation, chemical vapor deposition (CVD), plasma-enhanced chemical vapor deposition (PECVD), low-pressure chemical vapor deposition (LPCVD), etc.

The magnetic field-assisted sputtering deposition process is particularly used. The conditions for deposition of layers are widely documented in the literature, for example in patent applications WO2012/093238 A1 and WO2017/00602 A1.

A second aspect of the invention relates to glazing, in particular single, double or triple glazing, comprising a transparent substrate according to any of the embodiments described.

A monolithic glazing comprises a single substrate, in particular a sheet of mineral glass. It may be a single glazing. When the substrate according to the invention is used as a monolithic glazing, the functional stack of thin layers is preferably deposited on the face of the substrate facing the inside of the room of the building on the walls of which the glazing is installed. In such a configuration, it may be advantageous to protect the first layer and possibly the stack of thin layers against physical or chemical degradation using an appropriate means.

Multiple glazing comprises at least two substrates, in particular mineral glass sheets, parallel separated by a layer of insulating gas. Most multiple glazings are double or triple glazings, i.e. they comprise two or three panes respectively. When the substrate according to the invention is used as an element of multiple glazing, the functional stack of thin layers is preferably deposited on the face of the glass sheet facing inwards in contact with the insulating gas. This arrangement has the advantage of protecting the stack from chemical or physical degradation in the external environment.

Such a stack of thin layers 14 can be used in a laminated glass pane providing a separation between an exterior space and an interior space. This laminated glass pane is made up of two glass substrates, which are held together by an interlayer sheet of plastic material.

Such a stack of thin layers 14 can also be used in multiple glazing 100 providing a separation between an exterior space ES and an interior space IS; this glazing can have a double glazing structure, as illustrated in Or : this glazing is then made up of two glass substrates 10, 30, which are held together by a frame structure 90 and which are separated from each other by an interposed gas blade 15.

In And , the incident direction of sunlight entering the building is illustrated by the double arrow, top or left.

According to a first embodiment, illustrated in , the stack 14 of thin layers is positioned on face 2 (on the outermost sheet of the building considering the incident direction of the sunlight entering the building and on its face facing the gas blade), that is to say on an inner face 11 of the substrate 10 in contact with the intercalary gas blade 15, the other face 9 of the substrate 10 being in contact with the external space ES. The substrate 30, not carrying a stack in , has a face 29 in contact with the intermediate gas blade 15, the other face 31 of the substrate 30 being in contact with the interior space IS; this substrate 30 may comprise a stack of thin layers on one of its faces or both of its faces.

According to a second embodiment, illustrated in , the stack 14 of thin layers is positioned on face 3 (on the innermost sheet of the building considering the incident direction of the sunlight entering the building and on its face facing the gas blade), that is to say on an inner face 11 of the substrate 10 in contact with the intercalary gas blade 15, the other face 9 of the substrate 10 being in contact with the interior space IS. The substrate 30, not carrying a stack, has a face 29 in contact with the intercalary gas blade 15, the other face 31 of the substrate 30 being in contact with the exterior space ES.

However, it can also be envisaged that in this double glazing structure, one of the substrates has a laminated structure.

According to a third aspect of the invention, there is provided a method of manufacturing a transparent substrate according to the first aspect of the invention, such that the tungsten oxide layer is deposited by a magnetron sputtering method using a tungsten or tungsten oxide target, the material constituting said target being optionally doped using a chemical element chosen from the chemical elements of group 1 according to the IUPAC nomenclature.

When a pure tungsten metal target or a pure tungsten oxide target is used, it can be used to deposit a layer of pure substoichiometric tungsten oxide, WO _x , with x preferably between 2.55 and 2.98.

An advantage of using a ceramic target (i.e. with oxygen) over a metal target, especially for rotating targets, is that the ceramic target is lighter; it is therefore easier to control the process using this ceramic target.

When a ceramic or metallic target is used, it may in particular contain one or more doping elements in a proportion as described for the doped tungsten oxide layer in certain embodiments of the first aspect of the invention.

The tungsten layer(s) may be deposited by sputtering using the aforementioned target under an atmosphere comprising 0% to 50%, preferably 5% to 25% of dioxygen under a pressure of between 1 and 15 mTorr, preferably 3 to 10 mTorr. Preferably, the deposition is carried out cold, i.e. at a temperature below 100°C, in particular between 20°C and 60°C, for the substrate.

All the embodiments described, whether they relate to the first or second aspect of the invention, can be combined with each other without any particular modification or adaptation. In the event that technical incompatibilities arise when implementing one of these combinations, it is within the reach of those skilled in the art to be able to resolve them using their knowledge without this requiring undue effort, in particular by implementing a research program.

Examples

The features and advantages of the invention are illustrated by the examples and counterexamples described below.

In the following examples, the functional metal layers 140, 180 are silver (Ag) layers. The blocking layers 130, 150, 170, 190 are nickel-chromium alloy (NiCr) metal layers. The dielectric modules 120, 160, 200 comprise barrier layers, smoothing layers or wetting layers. The barrier layers are based on silicon nitride, doped with aluminum (Si ₃ N ₄ :Al), based on silicon nitride and zirconium. The smoothing layers are based on mixed zinc and tin oxide (SnZnOx). The wetting layers are made of zinc oxide (ZnO).

Name Content Stoichiometry Hint
(at 550 nm) CWO Cesium-doped tungsten oxide Cs/W = 0.05 2.45 for C1
2.20 for C2 SiN Aluminum-doped silicon nitride If ₃ N ₄ :Al 2.07 SiZrN17 Silicon zirconium nitride If _x' Zr _y' N _z' with
y / (y + x) = 0.17 2.20 ZnO Zinc oxide ZnO 2.00 SnZnO Zinc-tin oxide Sn _e Zn _f O 2.00 TiOx Titanium oxide- TiO ₂ or close 2.20 NiCr Nickel-Chromium Alloy Ni _0.8 Cr _0.2 - Ag Ag -

The deposition conditions of the layers, which were deposited by sputtering (so-called “magnetron cathode sputtering”), are summarized in Table 2.

Layer Target used Deposit pressure Gas SiN Si:Al 92:8 wt% 3.2-6.10-3 mbar Ar /(Ar + N2) at 55% SiZrN17 Si:Zr:Al at 78:17:5% at. 2.10 ^-3 mbar Ar/(Ar + _N2 ) at 45% ZnO Zn:Al 98:2 wt% 1.8.10-3 mbar Ar /(Ar + O2) at 63% SnZnO Zn:Sn at 64:36% at. 2.10 ^-3 mbar Ar/(Ar + _O2 ) at 50% TiOx TiO ₂ 2.10 ^-3 mbar Ar/(Ar + _O2 ) at 95% NiCr Ni:Cr at 80:20% at. 2-3.10 ^-3 mbar Ar at 100% Ag Ag 8.10 ^-3 mbar Ar at 100%

at. = atomic

In the tables presenting the composition of the examples below, bearing odd numbers, the first two columns indicate the number of the layer or module, with reference to the and the third column indicates the material for these layers. For these examples, the tables detail the complete contents of the stacks starting from surface 11 of substrate 10, with a thickness of 6 mm, in the order indicated (the materials and physical thicknesses are in nanometers and the substrate carrying the stack, made of clear glass, is in the last line, at the bottom of the tables). In the following, CE corresponds to a series of counter-examples; E1, E2, E13', E13''', E24', E24'', E'15, E16', E25', E26' each correspond to a series of examples. In each series of examples or counter-examples, when the name ends with "a", the aim is to obtain a light transmission in double glazing of the order of 50%; when the name ends in "b", it is a question of aiming to obtain a light transmission in double glazing of the order of 60%; when the name ends in "c", it is a question of aiming to obtain a light transmission in double glazing of the order of 70%; when the name ends in "d", it is a question of aiming to obtain a light transmission in double glazing of the order of 75%. In each series of examples, when the name includes a "1" it means that the C1 layer was used and when the name includes a "2" it means that the C2 layer was used.

To enable the low light transmission of 50% in double glazing to be achieved, or sometimes even to enable the low light transmission of 60% in double glazing to be achieved, a metallic absorbent layer 125 is provided in the first dielectric module, between two nitride-based dielectric layers, as taught by international patent application No. WO 02/48065.

In a first series of examples E1a, E1b and E1c, the presence of the tungsten oxide layer C1 is tested in the first dielectric module 120 and the third dielectric module 200.

Tab. 3 CEa E1a CEb E1b CEc E1c 300 TiOx 1 1 1 1 1 1 206 SiN 33 5 34 17 34 32 200 200a CWO - 27 - 12 - 3 202 ZnO 5 5 5 5 5 5 190 NiCr 0.7 0.7 0.7 0.7 0.7 0.7 180 Ag 15.7 15.6 15.3 16.5 15.1 16.0 170 NiCr 0.2 0.2 - - - - 169 ZnO 5 5 5 5 5 5 140 168 SnZnO 10 10 10 10 10 10 164 SiN 65 75 67 73 66 71 162 ZnO 5 5 5 5 5 5 150 NiCr 0.7 0.7 0.7 0.7 0.7 0.7 140 Ag 13.8 16.1 12.9 15.8 12.5 14.3 130 NiCr 1 1 2.8 0.5 1.0 - 129 ZnO 5 5 5 5 5 5 120a CWO - 17 - 21 - 15 120 126 SiN 18 6 - - - - 125 NiCr 2.2 0.5 - - - - 124 SiN 5 5 32 5 26 5 10 glass 6 mm 6 mm 6 mm 6 mm 6 mm 6 mm

In the tables presenting the properties of the examples and counterexamples below, bearing even numbers, the solar factor, g, the selectivity, s, the luminous transmission, TL, the luminous reflection on the inner face, Rint, and on the outer face, Rext, as well as the color in transmission, in reflection on the inner face and in reflection on the outer face, were measured for each substrate of the examples and counterexamples assembled in a double glazing, as illustrated in the . The second glass substrate 30 is a soda-calcium-silicon mineral glass with a thickness of 4 mm. The thickness of the interlayer blade 15 composed of air with 90% argon is 16 mm. The stack 14 is arranged on face 2, i.e. on face 11 of the substrate 10.

The term "colour", used to describe a transparent substrate with a stack, means the colour as defined in the CIE 1976 L*a*b* colour space according to ISO 11664, in particular with a D65 illuminant and a visual field of 2° or 10° for the reference observer. It is measured in accordance with said standard. The measurements of the colour parameters a* and b*, in transmission (a*T, b*T), in external reflection (a*Rext, b*Rext) and in internal reflection (a*Rint, b*Rint) are grouped together.

The luminous transmission in the visible spectrum, TL, the solar factor, g, and the selectivity, s, and the internal reflection, Rint, and the external reflection, Rext, in the visible spectrum are defined, measured and calculated in accordance with the standards EN 410, ISO 9050 and/or ISO 10292.

Tab. 4 CEa E1a CEb E1b CEc E1c TL 49.0 49.0 59.0 59.4 69.0 69.0 g 26.0 23.6 31.6 29.0 37.7 35.9 s 1,881 2,073 1,866 2,047 1,828 1,924 a*T -6.9 -8.8 -5.8 -7.2 -4.1 -5.4 b*T -2.2 0.0 -2.4 -1.5 -0.3 -1.2 Rext 18.0 17.4 16.7 16.5 15.0 14.5 a*Rext -1.1 -1.0 -1.0 -2.1 -1.0 -1.0 b*Rext -4.2 -10.0 -6.5 -7.7 -7.8 -5.8 Rint 20.6 21.7 16.4 18.4 14.4 15.2 a*Rint -0.4 -6.0 0.0 -6.1 -0.9 -2.1 b*Rint -5.0 -4.8 -5.0 -5.0 -5.0 -5.0

Tab. 4 shows that the three examples E1a, E1b and E1c according to the invention have a light transmission TL similar to that of the counterexamples CEa, CEb and CEc respectively and a solar factor, g, better (lower) than those of the counterexamples CEa, CEb and CEc.

Tab. 4 shows that the three examples E1a, E1b and E1c according to the invention allow a gain (increase) in selectivity, s, compared, respectively, to the counter-examples CEa, CEb and CEc. This gain illustrates the synergistic effect of the combination of the tungsten oxide-based C1 layer with the first and third dielectric modules.

External and internal reflections are also low; they are less than 22%.

In a second series of examples E2a, E2b, E2c and E2d of substrate according to the first aspect of the invention the presence of the tungsten oxide layer C2 is tested in the first dielectric module 120 and in the third dielectric module 200. These examples are compared respectively to the same counter-examples CEa, CEb and CEc as previously and a counter-example CEd is added.

Tab. 5 CEa E2a CEb E2b CEc E2c CEd E2d 300 TiOx 1 1 1 1 1 1 1 1 206 SiN 33 5 34 5 34 5 35 20 200 200a WO _x - 18 - 16 - 21 - 9 202 ZnO 5 5 5 5 5 5 5 5 190 NiCr 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 180 Ag 15.7 19.9 15.3 22.2 15.1 16.7 14.9 19.0 170 NiCr 0.2 0.2 - 0.2 - - - - 169 ZnO 5 5 5 5 5 5 5 5 140 168 SnZnO 10 10 10 10 10 10 10 10 164 SiN 65 68 67 72 66 72 67 75 162 ZnO 5 5 5 5 5 5 5 5 150 NiCr 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 140 Ag 13.8 15.5 12.9 13.5 12.5 14.5 12.5 11.7 130 NiCr 1 1 2.8 0.2 1.0 0.6 - - 129 ZnO 5 5 5 5 5 5 5 5 120a WO _x - 24 - 25 - 17 23 120 126 SiN 18 14 - 10 - - - - 125 NiCr 2.2 2.9 - 1.4 - - - - 124 SiN 5 5 32 5 26 5 20 6 10 glass 6 mm 6 mm 6 mm 6 mm 6 mm 6 mm 6 mm 6 mm

Table 6 presents properties of these examples and counterexamples.

Tab. 6 CEa E2a CEb E2b CEc E2c CEd E2d TL 49.0 49.0 59.0 59.0 69.0 69.0 74.0 74.0 g 26.0 23.2 31.6 27.5 37.7 34.4 40.8 38.1 s 1,881 2,113 1,866 2,146 1,828 2,006 1,813 1,944 a*T -6.9 -9.0 -5.8 -6.6 -4.1 -4.9 -3.1 -4.0 b*T -2.2 -3.3 -2.4 0.5 -0.3 -1.0 1.9 1.0 Rext 18.0 8.7 16.7 13.4 15.0 15.0 15.4 14.1 a*Rext -1.1 -2.9 -1.0 -1.8 -1.0 -1.0 -0.9 -3.0 b*Rext -4.2 0.0 -6.5 0.1 -7.8 -4.2 -9.5 -5.9 Rint 20.6 15.9 16.4 18.0 14.4 15.4 15.1 14.8 a*Rint -0.4 -1.0 0.0 0.0 -0.9 -3.8 -2.7 -0.1 b*Rint -5.0 -5.0 -5.0 -5.5 -5.0 -1.3 -7.0 -4.4

Tab. 6 shows that the four examples E2a, E2b, E2c and E2d according to the invention have a light transmission TL similar to that of the counterexamples CEa, CEb, CEc and CEd respectively and a solar factor, g, better (lower) than those of the counterexamples CEa, CEb, CEc and CEd.

Tab. 6 shows that the four examples E2a, E2b, E2c and E2d according to the invention allow a gain (increase) in selectivity, s, compared, respectively, to the counter-examples CEa, CEb, CEc and CEd. This gain illustrates the synergistic effect of the combination of the tungsten oxide-based C2 layer with the first and third dielectric modules.

External and internal reflections are also low; they are less than 20%.

There summarizes the selectivities of examples E1a, E1b and E1c according to the invention, of examples E2a, E2b, E2c and E2d according to the invention and of counterexamples CEa, CEb, CEc and CEd and shows that the selectivity of the examples is always higher than that of the counterexamples for a similar light transmission.

In a third series of examples E13’a, E13’’’a, E13’b, E13’’’b, E13’c, and E13’’’c of substrate according to the first aspect of the invention the presence of the tungsten oxide layer C1 is tested in the first dielectric module 120 only for the examples having “ ‘ ” in their name and in the third dielectric module 200 only for the examples having a “ ’’’ ” in their name. These examples are compared respectively to the same counter-examples CEa, CEb and CEc as previously (for the properties only).

Tab. 7 E13’a E13’’’a E13’b E13’’’b E13’c E13’’’c 300 TiOx 1 1 1 1 1 1 206 SiN 34 19 34 7 35 17 200 200a CWO - 14 - 20 16 202 ZnO 5 5 5 5 5 5 190 NiCr 0.7 0.7 0.7 0.7 0.7 0.7 180 Ag 16.2 16.4 16.4 13.8 16.0 14.5 170 NiCr 0.2 0.2 0.2 0.2 - - 169 ZnO 5 5 5 5 5 5 140 168 SnZnO 10 10 10 10 10 10 164 SiN 67 65 71 71 71 70 162 ZnO 5 5 5 5 5 5 150 NiCr 0.7 0.7 0.7 0.7 0.7 0.7 140 Ag 14.8 12.9 15.3 14.6 14.6 13.5 130 NiCr - - 0.9 0.9 0 0 129 ZnO 5 5 5 5 5 5 120a CWO 9 - 22 - 16 120 126 SiN 9 31 - - - - 125 NiCr 1.8 2.4 - - - - 124 SiN 5 5 5 31 10 25 10 glass 6 mm 6 mm 6 mm 6 mm 6 mm 6 mm

Table 8 presents properties of these examples and compares them to the preceding counterexamples.

Tab. 8 CEa E13’a E13’’’a CEb E13’b E13’’’b CEc E13’c E13’’’c TL 49.0 49.4 49.1 59.0 60.0 60.0 69.0 69.0 69.0 g 26.0 25.9 25.2 31.6 30.5 30.8 37.7 35.9 36.6 s 1,881 1,908 1,950 1,866 1,968 1,950 1,828 1,921 1,886 a*T -6.9 -7.5 -9.0 -5.8 -6.7 -6.3 -4.1 -5.2 -4.8 b*T -2.2 -3.1 -3.0 -2.4 -3.0 -1.5 -0.3 -1.3 -0.5 Rext 18.0 18.0 10.6 16.7 16.5 16.8 15.0 15.0 14.6 a*Rext -1.1 -1.0 -3.0 -1.0 -1.0 -0.3 -1.0 -1.1 -1.0 b*Rext -4.2 0.0 -7.6 -6.5 -1.1 -11.5 -7.8 -4.2 -10.0 Rint 20.6 20.5 16.0 16.4 18.1 19.0 14.4 15.7 16.3 a*Rint -0.4 -0.7 -6.0 0.0 -1.5 -7.5 -0.9 -1.6 -5.2 b*Rint -5.0 -5.1 -5.0 -5.0 -6.2 0.8 -5.0 -5.0 -0.2

Tab. 8 shows that the six examples E13’a, E13’’’a, E13’b, E13’’’b, E13’c, and E13’’’c according to the invention have a light transmission TL similar to that of, respectively, the counterexamples CEa, CEb and CEc and a solar factor, g, better (lower) than those of the counterexamples CEa, CEb and CEc.

External and internal reflections are also low; they are less than 22%.

Comparing the properties of examples E13’a, E13’’’a, E13’b, E13’’’b, E13’c, and E13’’’c according to the invention with, respectively depending on the light transmission range, those of examples E1a, E1b and E1c according to the invention shows that the effect of the tungsten oxide-based layer is greater (lower solar factor) or similar when the first and third dielectric modules both comprise this tungsten oxide-based layer.

There summarizes the selectivities of examples E1a, E1b and E1c according to the invention, of examples E13'a, E13'b and E13'c according to the invention, of examples E13'''a, E13'''b and E13'''c according to the invention and of counter-examples CEa, CEb and CEc and shows that the selectivity of the examples is always higher than that of the counter-examples for a similar light transmission and that this selectivity is higher or similar (for the light transmission of 70%) when the first and third dielectric modules each comprise a layer based on tungsten oxide.

In a fourth series of examples, two examples, E24’c and E24’’c of substrate according to the first aspect of the invention test the presence of the tungsten oxide layer C2 in the first dielectric module 120 for the example E24’c and in the three dielectric modules 120, 160 and 200 for the example E24’’c. These examples are compared to the same example E2c as previously.

Tab. 9 E24’c E2c E24’’c 300 TiOx 1 1 1 206 SiN 34 5 7 200 200a WO _x - 21 19 202 ZnO 5 5 5 190 NiCr 0.7 0.7 0.7 180 Ag 15.6 16.7 16.3 170 NiCr - - - 169 ZnO 5 5 5 140 168 SnZnO 10 10 10 166 SiN - - 22 160a WO _x - - 15 164 SiN 70 72 29 162 ZnO 5 5 5 150 NiCr 0.7 0.7 0.7 140 Ag 16.1 14.5 14.2 130 NiCr 0.9 0.6 0.5 129 ZnO 5 5 5 120 120a WO _x 13 17 19 124 SiN 10 5 5 10 glass 6 mm 6 mm 6 mm

Table 10 presents properties of these examples and counterexamples.

Tab. 10 CEc E24’c E2c E24’’c TL 69.0 69.0 69.0 69.0 g 37.7 36.2 34.4 33.4 s 1,828 1,905 2,006 2,065 a*T -4.1 -4.5 -4.9 -5.5 b*T -0.3 -0.6 -1.0 -0.5 Rext 15.0 15.0 15.0 15.0 a*Rext -1.0 -1.0 -1.0 -2.9 b*Rext -7.8 -4.0 -4.2 -5.0 Rint 14.4 14.8 15.4 15.3 a*Rint -0.9 -1.6 -3.8 -5.3 b*Rint -5.0 -5.0 -1.3 -4.1

Tab. 10 shows that the three examples E24’c, E2c and E24’’c according to the invention allow a gain (increase) in selectivity, s, compared, respectively, to the counter-example CEc without tungsten oxide-based layer.

Tab. 10 shows that for a similar light transmission TL of the order of 70%, the solar factor, g, is better (lower) when each dielectric module has one (and only one) tungsten oxide layer (example E24’’c). The selectivity is slightly higher (although in practice very close), when a tungsten oxide layer is provided in the first and last dielectric module (example E2c).

Comparison of the properties of examples E24’’c and E24c according to the invention shows that the effect of the tungsten oxide-based layer is greater (lower solar factor) when all three dielectric modules comprise a tungsten oxide-based layer compared to a configuration in which only the first dielectric module comprises a tungsten oxide-based layer.

External and internal reflections are also low; they are less than 20%.

In another series of examples E15'a, E16'a, E15'b, E16'b, E15'c, and E16'c of substrate according to the first aspect of the invention the presence of the tungsten oxide layer C1 is tested in the first dielectric module 120 for all these examples with in addition:
- for the E15' series: a high refractive index dielectric layer based on nitride 204 in the third dielectric module 200; and
- for the E16' series: an oxide-based contact layer 203 in the third dielectric module 200. These examples are compared to the same examples E13'a, E13'b and E13'c as previously (for the properties).

Tab. 11 E15’a E16’a E15’b E16’b E15’c E16’c 300 TiOx 1 1 1 1 1 1 206 SiN 6 5 5 5 5 10 204 SiZr17N 21 - 23 - 24 - 200 200a CWO - - - - - - 203 TiOx - 24 - 24 - 20 202 ZnO 5 - 5 - 5 - 190 NiCr 0.7 - 0.7 - 0.7 - 180 Ag 18.8 19.3 17.8 18.8 17.0 18.1 170 NiCr 0.2 0.2 - - - - 169 ZnO 5 5 5 5 5 5 140 168 SnZnO 10 10 10 10 10 10 164 SiN 69 69 71 71 71 71 162 ZnO 5 5 5 5 5 5 150 NiCr 0.7 0.7 0.7 0.7 0.7 0.7 140 Ag 14.7 15.3 15.3 14.4 14.5 16.7 130 NiCr 1.0 1.0 1.3 3.0 - - 129 ZnO 5 5 5 5 5 5 120a CWO 15 13 24 19 16 16 120 126 SiN 9 31 - - - - 125 NiCr 1.8 1.7 - - - - 124 SiN 7 6 5 5 10 10 10 glass 6 mm 6 mm 6 mm 6 mm 6 mm 6 mm

Table 12 presents properties of these examples and compares them to the preceding counterexamples.

Tab. 12 E13’a E15’a E16’a E13’b E15’b E16’b E13’c E15’c E16’c TL 49.4 49.9 49.8 60.0 59.2 59.6 69.0 69.0 69.0 g 25.9 24.8 24.7 30.5 29.3 29.2 35.9 35.3 34.8 s 1,908 2,015 2,013 1,968 2,024 2,040 1,921 1,952 1,983 a*T -7.5 -8.3 -6.9 -6.7 -6.6 -5.6 -5.2 -5.1 -5.2 b*T -3.1 -1.7 -2.9 -3.0 -2.3 -2.2 -1.3 -0.9 -1.4 Rext 18.0 15.5 17.9 16.5 16.3 16.2 15.0 15.0 15.0 a*Rext -1.0 -2.3 -3.0 -1.0 -2.3 -3.0 -1.1 -1.0 -1.0 b*Rext 0.0 0.0 0.0 -1.1 -2.1 -2.2 -4.2 -4.0 -4.0 Rint 20.5 18.5 20.3 18.1 18.0 16.4 15.7 15.7 15.6 a*Rint -0.7 -0.5 -2.7 -1.5 -3.0 -2.3 -1.6 -2.1 -1.3 b*Rint -5.1 -5.0 -5.0 -6.2 -5.7 -5.6 -5.0 -2.8 -3.9

Tab. 12 shows that the six examples E15’a, E16’a, E15’b, E16’b, E15’c, and E16’c according to the invention have a light transmission TL similar to that of, respectively, the counterexamples CEa, CEb and CEc and a solar factor, g, better (lower) than those of the counterexamples CEa, CEb and CEc.

Tab. 12 shows that the six examples E15’a, E16’a, E15’b, E16’b, E15’c, and E16’c according to the invention allow a gain (increase) in selectivity, s, compared, respectively, to examples E13’a, E13’b, and E13’c. This gain illustrates the synergistic effect of the combination of the tungsten oxide-based layer C1 in the first dielectric module with in the third dielectric module: a high refractive index dielectric layer based on nitride 204 or a contact layer based on oxide 203.

External and internal reflections are also low; they are less than 22%.

There summarizes the selectivities of examples E1a, E1b and E1c according to the invention, examples E13'a, E13'b and E13'c according to the invention, examples E15'a, E16'a, E15'b, E16'b, E15'c, and E16'c according to the invention and counter-examples CEa, CEb and CEc and shows that the selectivity of the examples is always higher than that of the counter-examples for a similar light transmission and that this selectivity is higher or similar for the low light transmissions of 50% and 60% when the first and third dielectric modules each comprise a tungsten oxide-based layer. For medium or high light transmissions (70% or more), it may be preferable to provide a single tungsten oxide-based layer in the first dielectric module; a high refractive index nitride-based dielectric layer or an oxide-based contact layer in the third dielectric module can promote the achievement of high selectivity.

Examples E25’a, E25’b and E25’c according to the invention and examples E26’a, E26’b and E26’c according to the invention were made in a similar manner, respectively one by one to examples E15’a, E15’b, E15’c E16’a, E16’b, and E16’c according to the invention by replacing only the layer C1 with the layer C2; examples E25’d and E26’d were further designed for double glazing configurations having a light transmission of approximately 75%. Examples E24’a, E24’b and E24’d according to the invention were produced in a similar manner, respectively one by one to examples E2a, E2b and E2d according to the invention using a single layer C2, in the first dielectric module (i.e. without a layer in the third dielectric module), as for example E24’c presented above.

There summarizes the selectivities of examples E2a, E2b, E2c and E2d according to the invention, of examples E24'a, E24'b, E24'c, and E24'd according to the invention, of examples E25'a, E25'b, E25'c, and E25'd according to the invention, of examples E26'a, E26'b, E26'c and E26'd according to the invention and of counter-examples CEa, CEb, CEc and CEd. This shows that the selectivity of the examples is always higher than that of the counterexamples for a similar light transmission. This further shows that this selectivity is higher or similar when the first and third dielectric modules each have a tungsten oxide-based layer for low light transmissions of 50% and 60% or for the average light transmission of 70%. For high light transmissions (more than 70%), it may be preferable to provide a single tungsten oxide-based layer in the first dielectric module; a high refractive index nitride-based dielectric layer or an oxide-based contact layer in the third dielectric module may help achieve high selectivity.

These examples very clearly illustrate the advantages of the substrates of the invention, namely that they have a reduced solar factor, higher selectivity, and exhibit a neutral color, both in transmission and for reflections.

Claims (16)

Glass substrate (10) provided with a functional stack (14) of thin layers on at least one of its faces (11), said functional stack (14) comprising, starting from the substrate (10) at least two metallic functional layers (140, 180), preferably each based on silver, each located between two dielectric modules (120, 160, 200) of thin layers and forming a succession comprising a first dielectric module (120), a first metallic functional layer (140), a second dielectric module (160), a second metallic functional layer (180) and a last dielectric module (200), and in which at least one of the dielectric modules (120, 160, 200) of thin layers comprises a layer of tungsten oxide (120a, 160a, 200a), and the tungsten oxide optionally comprising at least one doping element selected from the chemical elements of group 1 according to the IUPAC nomenclature. Substrate (10) according to claim 1, such that said functional stack (14) comprises a single layer of tungsten oxide (120a, 160a, 200a) and said layer of tungsten oxide (120a, 160a, 200a) is preferably located in said first dielectric module (120) or in said last dielectric module (200). Substrate (10) according to claim 1, such that said functional stack (14) comprises two tungsten oxide layers (120a, 160a, 200a) and said tungsten oxide layers (120a, 160a, 200a) are preferably located for one in said first dielectric module (120) and for the other in said last dielectric module (200). Substrate (10) according to claim 1, such that said functional stack (14) comprises as many layers of tungsten oxide (120a, 160a, 200a) as dielectric modules (120, 160, 200) and each dielectric module (120, 160, 200) comprises a layer of tungsten oxide (120a, 160a, 200a). Substrate (10) according to any one of claims 1 to 4, such that the optical refractive index of the tungsten oxide layer(s) (120a, 160a, 200a) decreases monotonically with wavelength from a maximum value greater than 2.4 at 350 nm to a minimum value between 600 nm and 900 nm such that the difference between the maximum value and the minimum value is greater than 0.8, preferably greater than 1.0, or even greater than 1.4. Substrate (10) according to any one of claims 1 to 5, such that the optical extinction coefficient of the tungsten oxide layer(s) (120a, 160a, 200a) is less than 0.2 at 500 nm and less than 2.0 at 1200 nm. Substrate (10) according to any one of claims 1 to 6, such that the tungsten oxide layer(s) (120a, 160a, 200a) is (or are) made of pure substoichiometric tungsten oxide, WOx, with x preferably between 2.55 and 2.98. Substrate (10) according to any one of claims 1 to 6, such that the tungsten oxide layer(s) (120a, 160a, 200a) comprises (comprise) a doping element, or several doping elements, in a proportion such that the molar ratio of said element to tungsten, or the sum of the molar ratios of each element to tungsten, is between 0.01 and 0.4, preferably between 0.01 and 0.2, or even between 0.01 and 0.1. Substrate (10) according to any one of claims 1 to 6, 8, such that the tungsten oxide layer(s) (120a, 160a, 200a) comprises (comprise) at least one doping element selected from hydrogen, lithium, sodium, potassium and cesium. Substrate according to claim 9, such that the tungsten oxide layer(s) (120a, 160a, 200a) comprises cesium as a doping element, and the molar ratio of cesium to tungsten is between 0.01 and 0.2, preferably between 0.01 and 0.1. Substrate (10) according to any one of claims 1 to 10, such that the physical thickness of the tungsten oxide layer(s) (120a, 160a, 200a) is (or are) between 2 nm and 50 nm, in particular between 5 nm and 30 nm, preferably between 5 nm and 20 nm. Substrate (10) according to any one of claims 1 to 11, such that said functional stack (14) of layers further comprises at least one blocking overlayer (150, 190), preferably based on a nickel and chromium alloy, located above and in contact with a metallic functional layer (140, 180) and/or at least one metallic blocking underlayer (130, 170), preferably based on a nickel and chromium alloy, located below and in contact with a metallic functional layer (140, 180). Substrate (10) according to any one of claims 1 to 12, such that the functional stack of layers further comprises an oxide-based contact layer (203), made of titanium oxide, located above and in contact with the metallic functional layer (180) furthest from the substrate, said oxide-based contact layer (203) preferably having a physical thickness of at least 5.0 nm, in particular between 5.0 and 35.0 nm. Substrate (10) according to any one of claims 1 to 13, such that the functional stack (14) of layers comprises a layer with a refractive index greater than 2.15 at 550 nm, said layer being included in the last dielectric module (200). Glazing comprising at least two transparent substrates, one of the substrates being a substrate according to any one of claims 1 to 14 arranged so that the functional stack of layers is located on face two and/or face three of said glazing. Method for manufacturing a transparent substrate according to any one of claims 1 to 14, such that the tungsten oxide layer(s) (120a, 160a, 200a) is (or are) deposited by a magnetron sputtering method using a tungsten or tungsten oxide target, the material constituting said target being optionally doped using a chemical element chosen from the chemical elements of group 1 according to the IUPAC nomenclature.