TRANSPARENT SUBSTRATE WITH A FUNCTIONAL STACK OF THIN LAYERS

Description

Technical domain

[0001] The invention relates to a transparent substrate provided with a functional stack of thin layers. Technical Background

[0002] 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 benefit is that they reduce air conditioning efforts by preventing excessive overheating (so-called "solar control" glazing) and / or by reducing the amount of energy dissipated to the outside (so-called "low-emissivity" glazing).

[0003] 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.

[0004] 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.

[0005] Solar control features are required for glazing that is 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.

[0006] JP H0812378 A [NISSAN MOTOR] 16.01.1996 describes a "solar control" functional stack comprising a tungsten oxide layer disposed between two dielectric layers. The stack makes it possible to reduce the surface electrical resistance and increase the transparency to radio waves compared to stacks comprising a metallic functional layer, in particular based on silver.

[0007] JP 2010180449 A [SUMITOMO METAL MINING CO [JP]] 19.08.2010 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.

[0008] EP 3686312 A1 [SUMITOMO METAL MINING CO [JP]] 29.07.2020 describes a layer based on cesium-doped tungsten oxide, and a method for depositing such a layer by cathode sputtering. The layer has transparency to radio waves and a "solar control" function thanks, in particular, to its strong absorption of infrared radiation.

[0009] US 6,040,939 A describes a glass substrate provided with a solar control and low-emissivity stack comprising a silver-based functional layer and tungsten oxide-based dielectric layers. Summary of the Invention Technical problem

[0010] For certain applications, for example in the building and construction markets, it is desirable for the functional stack to have a high light transmission, TL, in the visible range, in particular greater than 67% or even 77%, in order to ensure sufficient and comfortable natural illumination of interiors and to reduce the use of artificial domestic lighting.

[0011] A functional stack is considered suitable for such applications when it meets a triple requirement: high light transmission, low solar factor value and low emissivity value. A functional stack is therefore suitable when it has a high selectivity value, s, defined as the ratio of light transmission to solar factor, and low emissivity.

[0012] State-of-the-art solutions consisting of using only infrared radiation-absorbing layers as functional layers in the functional stack are not suitable because they have a higher emissivity, which is incompatible, for example, with applications in the residential market.

[0013] There therefore remains a need for a functional stack suitable for “solar control” applications in a residential market, i.e. presenting high selectivity and suitable overall energy performance, particularly concerning emissivity. Solution to technical problem

[0014] According to a first aspect of the invention, there is provided a transparent substrate provided with a functional stack of thin layers as described in claim 1, the dependent claims being advantageous embodiments.

[0015] According to a second aspect of the invention, there is provided a glazing comprising a transparent substrate according to the first aspect of the invention.

[0016] According to a third aspect of the invention, there is provided a method for manufacturing a transparent substrate according to the first aspect of the invention. Advantages of the invention

[0017] A first advantage of the invention is that it provides a suitable "solar control" functional stack, particularly for applications in the building and construction markets. The functional stack meets the triple requirement of high light transmission, low solar factor value, and low emissivity. It has high selectivity and suitable overall energy performance.

[0018] By way of examples, a transparent substrate provided with a functional stack in accordance with the first aspect of the invention may, compared to a conventional functional stack, have a solar factor value lower by at least 2%, or even at least 4%, and an equivalent light transmission, or even higher by at least 1%, or even at least 2%.

[0019] A second advantage is that the tungsten oxide layer does not affect, or at least only slightly, the color of the stack compared to a conventional functional stack. Color specifications are therefore always met when such a layer is introduced into an existing functional stack.

[0020] Another advantage of the invention is that the tungsten oxide layer can be deposited by a magnetron sputtering method, in particular using a tungsten oxide target. Since functional stacks of thin layers are generally deposited by a magnetron sputtering method, existing methods can be more easily adapted. Brief description of the drawings

[0021] [ Fig.1 ] a schematic representation of a first embodiment of the first aspect of the invention. [ Fig.2 ] a schematic representation of a second embodiment of the first aspect of the invention. [ Fig.3 ] is a representation of the evolution of the optical extinction coefficient of several examples of cesium-doped tungsten oxide layer as a function of wavelength. [ Fig.4] is a representation of the evolution of the optical refractive index of several examples of cesium-doped tungsten oxide layer as a function of wavelength [ Fig.5 ] a schematic representation of a third embodiment of the first aspect of the invention. [ Fig.6 ] a schematic representation of a fourth embodiment of the first aspect of the invention. [ Fig.7 ] a schematic representation of a fifth embodiment of the first aspect of the invention. [ Fig.8 ] a schematic representation of a sixth embodiment of the first aspect of the invention [ Fig.9 ] is a schematic representation of a first embodiment of a glazing according to the second aspect of the invention. [ Fig.10 ] is a schematic representation of a second embodiment of a glazing according to the second aspect of the invention. [ Fig.11] is a graphical representation of the light transmission and the solar factor for seventeen examples of glazing according to the invention and four counter-examples. [ Fig.12 ] is a graphical representation of the light reflection on the inner face and outer face for seventeen examples of glazing according to the invention and four counter-examples. [ Fig.13 ] is a graphical representation of the color parameters a* and b* in transmission, internal reflection and external reflection for seventeen examples of glazing according to the invention and four counter-examples. Detailed description of achievement modes

[0022] It uses the following definitions and conventions.

[0023] 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", in no way 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.

[0024] 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.

[0025] 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, real or geometric thickness of a dielectric module of layers corresponds to the sum of the physical, real or geometric thicknesses of each of the layers that constitute it.

[0026] 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.

[0027] By the term "transparent", used to describe a substrate, means 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.

[0028] By "light transmission" is meant the light transmission, noted TL, as defined and measured in section 4.2 of standard EN 410.

[0029] 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.

[0030] According to the IUPAC nomenclature, Group 1 of the chemical elements includes hydrogen and the alkali elements, i.e., lithium, sodium, potassium, rubidium, cesium, and francium.

[0031] The expressions "optical refractive index" and "optical extinction coefficient" mean the optical refractive index, n, and the 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, ED (ed.), Academic Press, 1991, Chapter 7.

[0032] According to a first aspect of the invention, with reference to [ Fig.1] and [Fig.2 ], a transparent substrate (1000) is provided with a functional stack (1001) of thin layers on at least one of its faces (1000a, 1000b), said functional stack (1001) comprising, starting from the substrate (1000): at least one metallic functional layer (1003) placed between two dielectric modules (1002,1004) of thin films, and wherein at least one of the dielectric modules (1002,1004) of thin films comprises a layer (1002a,1004a) of tungsten oxide, and the tungsten oxide comprises at least one doping element selected from the chemical elements of group 1 according to the IUPAC nomenclature.

[0033] 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 a metallic functional layer have a synergistic effect on increasing selectivity.

[0034] 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, for a layer of tungsten oxide doped with cesium deposited by cathodic sputtering on a soda-lime-silica glass substrate according to three deposition conditions are represented on the [ Fig.3] and [Fig.4] respectively. The molar ratio of cesium to tungsten is about 0.05-0.06.

[0035] Layers C1, C2 and C3 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, C2 and C3 is encapsulated between two silicon nitride-based layers.

[0036] The encapsulation of layers C1, C2 and C3 by two layers based on silicon nitride serves to prevent the degradation of layers C1, C2 and C3 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.

[0037] Layer C1 was deposited under an atmosphere comprising 25% oxygen at a pressure of 4 mTorr, layer C2 under an atmosphere comprising 20% ​​oxygen at a pressure of 4 mTorr and layer C3 under an atmosphere comprising 5% oxygen at a pressure of 10 mTorr.

[0038] The stacks thus obtained comprising layers C1, C2 and C3 were annealed at 650°C for 10 min after deposition.

[0039] The extinction coefficient and refractive index were calculated by modeling from experimental measurements. The measurements were obtained using a Perkin Elmer Lambda 900 spectrophotometer and a VASE M-2000XI JA Wollam ellisopmeter.

[0040] With reference to the [ Fig.3], regardless of the C1, C2 or C3 layer, the extinction coefficient decreases monotonically from a value below 1 at 300 nm to reach a minimum level below 0.1 between approximately 400 nm and 550 nm, then increases monotonically to reach a value above 1.2 around 1200 nm. The C1, C2 and C3 layers exhibit strong absorption in the near infrared and some transparency in the visible region of the electromagnetic spectrum.

[0041] With reference to the [ Fig.4], regardless of the layer C1, C2 or C3, 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 approximately 800 nm and 1100 nm, then increases monotonically to reach a value greater than 1.8, or even 2 towards 1300-1400 nm. The changes in the optical refractive index and the optical extinction coefficient show a certain variation between the three layers C1, C2 and C3. This very moderate variability is probably due to the deposition conditions and is not detrimental to obtaining the advantages of the present invention.

[0042] According to other preferred embodiments, the optical refractive index of the tungsten oxide layer (1002a, 1004a) decreases monotonically with wavelength from a maximum value greater than 2.4 at 350nm to a minimum value between 600nm and 900nm such that the difference between the maximum value and the minimum value is greater than 0.8, preferably 1.0, or even 1.4.

[0043] 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 350nm and a minimum value between 600nm and 900nm. For 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 350nm and a minimum value less than 2.3 between 600nm and 900nm, in particular between 800nm ​​and 900nm.

[0044] Although not particularly required to achieve the effects of the present invention, these optical refractive index values ​​may nevertheless be advantageous in meeting color specifications for applications in the building and construction markets. In particular, they allow neutral colors to be obtained.

[0045] According to certain additional preferred embodiments, the optical extinction coefficient of the tungsten oxide layer 1002a, 1004a may be less than 0.2, or even 0.1 at 500nm and less than 2, or even 1.5 at 1200nm. The selectivity can thus be favorably further increased.

[0046] The optical extinction coefficient and the optical diffraction index may vary depending on 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 [ Fig.3] and [Fig.4 ]. 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).

[0047] According to certain particular embodiments, the layer 1002a, 1004a of tungsten oxide comprises the doping element X or the doping elements X1, X2,... in proportions 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, as well as a reduction in costs.

[0048] According to certain embodiments, the tungsten oxide layer 1002a, 1004a comprises at least one doping element selected from hydrogen, lithium, sodium, potassium and cesium. Among the group 1 elements, these particular elements can make it possible to obtain the most optimal optical extinction coefficient and refractive index values ​​for the desired technical effects.

[0049] According to particularly preferred embodiments, the tungsten oxide layer 1002a, 1004a 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 make it possible to obtain the best performances with regard to the increase in selectivity, the preservation of neutral colors, and cost savings.

[0050] The transparent substrate 1000 may preferably be planar and may be of an organic or inorganic nature, rigid or flexible. In particular, it may be a mineral glass, for example a soda-lime-silica glass.

[0051] 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.

[0052] Examples of mineral substrates that can be advantageously used 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 transparent substrate 1000 is a soda-lime-silica mineral glass sheet.

[0053] With reference to the [ Fig.1], according to advantageous embodiments, the tungsten oxide layer 1002a may be included in the dielectric module 1002 of layers located under the metal functional layer 1003, between said substrate 1000 and said metal functional layer 1003. The presence of the tungsten oxide layer 1002a in the dielectric module 1002 of layers located under the metal functional layer 1003 makes it possible both to reduce the solar factor value and / or to increase the light transmission.

[0054] With reference to the [ Fig.5 ], according to preferred embodiments, each dielectric module 1002,1004 of layers comprises a layer 1002a,1004a of tungsten oxide. The presence of the tungsten oxide layer 1002a,1004a in each dielectric module 1002,1004 allows for the greatest reductions in solar factor and the greatest increases in light transmission.

[0055] According to certain advantageous embodiments, the physical thickness of the layer(s) 1002a, 1004a of tungsten oxide may be between 2nm and 50nm, in particular between 5nm and 30nm, preferably between 5nm and 20nm. These thickness ranges are sufficient to obtain the remarkable advantages of the first aspect of the invention.

[0056] According to embodiments, with reference to the [ Fig.6 ], the functional stack 1001 of layers further comprises a blocking metal overlayer 6002, preferably based on a nickel and chromium alloy, located above and in contact with the metal functional layer 1003 and / or a blocking metal underlayer 6001, preferably based on a nickel and chromium alloy, located below and in contact with the metal functional layer 1003.

[0057] The presence of a blocking metal overlayer 6002 and / or a blocking metal underlayer 6001 makes it possible to advantageously increase the durability of the stack, for example in terms of mechanical resistance to brushing or scratching. It also makes it possible to avoid deterioration, for example oxidation, of the metal functional layer 1003 during the deposition of subsequent layers and / or during heat treatments, in particular by limiting the diffusion of certain chemical elements from the adjacent layers and / or the diffusion of oxygen.

[0058] According to other embodiments, with reference to the [ Fig.7], the functional stack 1001 of thin layers may further comprise a titanium oxide overlayer 7001 located above, preferably in contact with, the metallic functional layer 1003, said overlayer 4000 preferably having a physical thickness of at least 5 nm. The titanium oxide overlayer 7001 makes it possible to increase the selectivity.

[0059] According to particular embodiments, with reference to the [ Fig.8 ], the functional stack 1001 of layers comprises a layer 8001 with a refractive index of less than 2.45 at 550nm, said layer being included in the dielectric module 1004 of layers forming the upper part of the functional stack 1001 starting from the substrate 1000. Preferably, said layer 8001 is the last layer of the dielectric module 1004.

[0060] The combination of a layer of refractive index less than 2.45 at 550nm in the last dielectric module 1004 with a layer 1002a, 1004a of tungsten oxide in the first and / or second dielectric modules 1002, 1004 makes it possible to prevent any structural degradation of the layer(s) 1002a, 1004a of tungsten oxide by the possible diffusion of elements, such as oxygen, from the adjacent layers.

[0061] According to other particular embodiments, the functional stack 1001 of layers comprises a layer with a refractive index of less than 2.45 at 550nm, said layer being included in the dielectric module 1002 of layers forming the lower part of the functional stack 1001 starting from the substrate 1000.

[0062] According to preferred embodiments, the functional stack 1001 of layers comprises a first layer with a refractive index of less than 2.45 at 550nm, said first layer being included in the dielectric module 1002 of layers forming the lower part of the functional stack 1001 starting from the substrate 1000, and a second layer with a refractive index of less than 2.45 at 550nm, said second layer being included in the dielectric module 1004 of layers forming the upper part of the functional stack 1001 starting from the substrate 1000.

[0063] The layer(s) with a refractive index of less than 2.45 at 550nm are preferably based on silicon, zirconium, titanium, or tin and zinc oxide or nitride. For example, they may be based on silicon nitride, silicon oxide, zirconium nitride or zinc and tin oxide.

[0064] The metal functional layer 1003 has the function of reflecting infrared radiation and / or part of the solar radiation. It can be made of any suitable metal, for example gold-based or silver-based. The thickness of the metal functional layer 1003 can typically be between 2nm and 25nm, preferably between 10nm and 20nm.

[0065] According to preferred embodiments, the metal functional layer 1003 is a silver-based layer.

[0066] The dielectric modules may comprise one or more layers of oxides and / or nitrides of metallic elements and / or metallic 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.

[0067] The methods for depositing thin layers on substrates, in particular glass substrates, are well-known methods in the industry. For example, the deposition of a stack of thin layers on a glass substrate is carried out by successively depositing each thin layer of said stack by passing the glass substrate through a succession of deposition cells adapted to deposit a given thin layer.

[0068] 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.

[0069] The magnetic field-assisted sputtering 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.

[0070] 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.

[0071] A monolithic glazing unit comprises a single substrate, in particular a sheet of mineral glass. It may be a single glazing unit. When the substrate according to the invention is used as a monolithic glazing unit, the functional stack of thin layers is preferably deposited on the face of the substrate facing the interior of the room of the building on the walls of which the glazing unit 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 damage using a suitable means.

[0072] A multiple glazing unit comprises at least two substrates, in particular mineral glass sheets, parallel and separated by a layer of insulating gas. Most multiple glazing units are double or triple glazing units, i.e. they comprise two or three panes of glass respectively. When the substrate according to the invention is used as an element of a multiple glazing unit, 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 damage from the external environment.

[0073] According to preferred embodiments, with reference to [ Fig.9 ] And [ Fig.10], the glazing is a double glazing 9000, 10000 comprising a transparent substrate 1000 according to one of any of the embodiments described previously arranged so that the functional stack 1001 of layers is located on face two and / or on face three of said glazing 9000, 10000. In the figure, (E) corresponds to the exterior of the room where the glazing is installed, and (I) to the interior of the room.

[0074] According to a first embodiment, with reference to the [ Fig.9 ], the glazing 9000 comprises a first transparent glass sheet 1000 with an inner surface 1000a and an outer surface 1000b, a second transparent glass sheet 9001 with an inner surface 9001a and an outer surface 9001b, an insulating gas layer 9002, a spacer 9003 and a sealing gasket 9004.

[0075] The glass sheet 1000 comprises, on and in contact with its inner surface 1000b in contact with the gas of the insulating gas layer 9002, a functional stack 1001 according to the first aspect of the invention. The functional assembly 1001 is preferably arranged so that its outer surface which is opposite that 1000b of the transparent glass sheet 1000 is oriented towards the interior (I) of the room, for example a building, in which the glazing is used. In other words, the functional stack 1001 is arranged on face 2 of the glazing starting from the exterior (E).

[0076] According to another embodiment, with reference to the [ Fig.10], the glazing is a double glazing 10000 comprising a first transparent glass sheet 1000 with an inner surface 1000a and an outer surface 1001b, a second transparent glass sheet 10001 with an inner surface 1001a and an outer surface 1001b, an insulating gas layer 10004, a spacer 10003 and a sealing gasket 10004.

[0077] The glass sheet 1000 comprises, on and in contact with its inner surface 1000a in contact with the gas of the insulating gas layer 9004, a functional stack 1001 according to the first aspect of the invention. The functional assembly 1001 is preferably arranged so that its outer surface which is opposite that 1000a of the transparent glass sheet 1000 is oriented towards the outside (E) of the room. In other words, the functional stack (1001) is arranged on face 3 of the glazing starting from the outside (E).

[0078] 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 oxide target doped with a chemical element selected from the chemical elements of group 1 according to the IUPAC nomenclature.

[0079] The tungsten oxide target may in particular contain one or more doping elements in the proportions as described for the doped tungsten oxide layer in certain embodiments of the first aspect of the invention.

[0080] 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 oxygen under a pressure of between 1 and 15 mTorr, preferably 3 to 10 mTorr. Preferably, the deposition may be carried out cold, i.e. at a temperature below 100°C, in particular between 20°C and 60°C, for the substrate.

[0081] 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 appear during the implementation of 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

[0082] The characteristics and advantages of the invention are illustrated by the examples and counter-examples described below.

[0083] Seventeen examples, E1 - E17, in accordance with the invention are described in Tables 1, 2 and 3 which indicate the composition and the thickness expressed in nanometers of the different layers. The numbers in the first two columns correspond to the references in the figures.

[0084] The layer, denoted CWO, of cesium-doped tungsten oxide. The molar ratio of cesium to tungsten is approximately 0.05-0.06. Tab. 1 E1 E2 E3 E4 E5 E6 TiOx 1.5 1.5 1.5 1.5 1.5 1.5 1004 Sign 41 42 41 17 41 24 SnZnO 5 SiZr 1004a CWO 19 7001 TiOx 20 ZnO 5 5 5 5 5 6002 NiCrO x 0.6 0.6 0.6 0.6 0.6 0.6 1003 Ag 16.6 16.6 17.0 17.5 16.6 16.3 1002 ZnO 5 5 5 5 5 5 1002a CWO 17 10 10 19 17 18 SiZr Sign 9 17 12 5 9 5 1000 remote 4mm 4mm 4mm 4mm 4mm 4mm Tab. 2 E7 E8 E9 E10 E11 E12 TiOx 1.5 1.5 1.5 1.5 1.5 1.5 1004 Sign 41 30 17 13 24 35 SnZnO 5 10 6 SiZr 1004a CWO 11 7001 TiOx 20 20 14 ZnO 5 5 5 6002 NiCrO x 0.6 0.6 0.6 1003 Ag 17.0 17.4 17.5 18.3 18.5 12.9 1002 ZnO 5 5 5 5 5 5 1002a CWO 10 15 19 19 16 15 SiZr Sign 12 5 5 5 5 22 1000 remote 4mm 4mm 4mm 4mm 4mm 4mm Tab. 3 E13 E14 E15 E16 E17 TiOx 1.5 1.5 1.5 1.5 1.5 1004 Sign 18 21 5 5 19 SnZnO 10 5 5 SiZr 1004a CWO 20 15 12 7001 TiOx 20 25 5 ZnO 5 5 6002 NiCrO x 0.6 0.6 1003 Ag 12.6 14.2 13.2 14.8 14.8 1002 ZnO 5 5 5 5 5 1002a CWO 23 20 18 24 20 SiZr Sign 5 5 19 5 5 1000 remote 4mm 4mm 4mm 4mm 4mm

[0085] Examples E1 to E5, E7, E9 to E12, E15 and E16 comprise only one layer 1002a of doped tungsten oxide in the first dielectric module 1002. Examples E6, E8, E13 to E14 and E17 comprise two layers 1002a, 1004a of doped tungsten oxide located in the first 1002 and second 1004 dielectric modules. The corresponding counterexamples are counterexamples CE1 and CE3.

[0086] Examples E9 to E11 and Examples E15 to E17 are examples consistent with certain advantageous embodiments in which a titanium oxide-based layer 7001 is located above and in contact with the metal functional layer 1003. Corresponding counterexamples are counterexamples CE2 and CE4.

[0087] Four counterexamples, CE1 - CE4 are described in Table 4 which indicates the composition and thickness expressed in nanometers of the different layers. Tab. 3 CE1 CE2 CE3 CE4 TiOx 1.5 1.5 1.5 1.5 1004 Sign 40 30 37 25 SnZnO SiZr 1004a CWO 7001 TiOx 5 10 ZnO 5 5 6002 NiCrOx 0.6 0.6 1003 Ag 17.0 18.5 13.4 15.7 1002 ZnO 5 5 5 5 1002a CWO SiZr 14 23 Sign 22 5 28 0 1000 remote

[0088] The thin-film stacks of the seventeen examples E1 - E17 and the counter-examples CE1 - CE4 were deposited by magnetic field-assisted sputtering (magnetron process) whose characteristics are widely documented in the literature, for example in patent applications WO2012 / 093238 and WO2017 / 00602. The substrate 1000 is a 4 mm thick soda-lime-silica mineral glass. After deposition, the substrates were heat treated at 650°C for 10 min.

[0089] The nature of the targets used and the deposition conditions of examples E1 to E17 and counter-examples CE1 - CE4 are grouped in Table 5. Tab. 5 Target Pressio n (µbar) The (sccm) O2 (sccm) N2 (sccm) Power (W) TiOx TiOx 2 10 2 0 2000 SnZnO Sn60Zn40 2 7 44 0 1000 Sign Sign 5 7 0 14 2000 SiZr Si:ZR 27 wt. % 2 15 0 15 1000 NiCrO x NiCr 2 20 0 0 70 Ag Ag 8 40 0 0 210 ZnO ZnO:Al 2 wt. % 2 40 2 0 1300 CWO CWO 4-10 30-40 2-10 0 1300

[0090] The solar factor, g, the selectivity, s, the light transmission, T1, the light reflection on the inner side, Rint, and on the outer side, Rext, as well as the color in transmission, on the inner side and on the outer side, were measured for each substrate of examples E1 to E17 and counter-examples CE1 to CE4 assembled in a double glazing, as illustrated in the [ Fig.9 ]. The second glass sheet 9001 is a soda-calcium-silicon mineral glass with a thickness of 4 mm. The thickness of the air layer 9002 is 16 mm. The stack is arranged on face 2, i.e. on face 1001b of the substrate 1000.

[0091] The term "color," used to describe a transparent substrate with a stack, means the color as defined in the CIE 1976 L*a*b* color 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.

[0092] 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.

[0093] The measurements of solar factor, selectivity, light transmission, internal reflection and external reflection are grouped in Table 6. The measurements of the color 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 in Table 7. Tab. 6 g s T1 Rint Rext E1 45,3 1,523 69,0 20,8 20,0 E2 45,9 1,503 69,0 21,0 20,0 E3 45,3 1,528 69,2 22,6 20,8 E4 43,8 1,575 69,0 20,7 19,1 E5 45,3 1,523 69,0 20,8 20,0 E6 44,8 1,564 70,0 23,7 21,7 E7 45,3 1,528 69,2 22,6 20,8 E8 44,0 1,593 70,0 23,4 21,3 E9 43,8 1,575 69,0 20,7 19,1 E10 44,0 1,593 70,0 23,2 20,8 E11 44,0 1,592 70,0 23,2 20,9 E12 54,7 1,428 78,2 12,1 12,4 E13 52,9 1,485 78,5 15,0 14,0 E14 50,5 1,554 78,5 14,6 13,7 E15 53,0 1,478 78,3 11,5 11,8 E16 51,2 1,534 78,5 14,5 13,5 E17 50,3 1,561 78,5 14,7 13,7 CE1 46,3 1,489 69,0 24,1 21,9 CE2 45,3 1,544 70,0 22,9 21,0 CE3 56,1 1,394 78,2 14,9 13,9 CE4 52,9 1,485 78,5 14,2 13,4 Tab. 7 a*T b*T a*Rext b*Rext a*Rint b*Rint E1 -4,0 -1,0 2,3 -3,4 4,1 -4,1 E2 -4,1 1,3 2,3 -3,7 4,5 -5,9 E3 -4,6 1,4 1,0 -3,5 3,4 -4,9 E4 -4,1 0,6 1,7 -6,8 3,8 -7,2 E5 -4,0 -1,0 2,3 -3,4 4,1 -4,1 E6 -3,9 3,0 3,0 -5,1 4,6 -7,1 E7 -4,6 1,4 1,0 -3,5 3,4 -4,9 E8 -4,1 3,0 2,2 -2,8 4,0 -5,0 E9 -4,1 0,6 1,7 -6,8 3,8 -7,2 E10 -4,0 3,0 2,9 -4,5 4,4 -6,1 E11 -4,0 3,0 2,0 -2,6 4,0 -5,2 E12 -3,5 -1,0 3,0 -4,7 4,9 -2,9 E13 -3,2 2,4 3,0 -7,2 4,4 -8,0 E14 -3,8 3,0 2,5 -4,8 4,3 -6,1 E15 -4,0 0,5 1,8 -8,0 4,7 -6,1 E16 -3,5 3,0 3,0 -7,2 4,3 -8,0 E17 -3,8 3,0 2,3 -4,5 4,1 -5,9 CE1 -3,6 4 3,2 -7,7 4,3 -8,1 CE2 -4,3 3,4 3,0 -3,8 4,7 -5,4 CE3 -2,9 2,7 3,1 -8,8 4,0 -8,0 CE4 -3,8 3,0 3,0 -4,8 4,8 -5,7

[0094] The values ​​of light transmission, TL, and solar factor, g, are shown in the [ Fig.11] for examples E1 to E17 (solid circles) and counterexamples CE1 to CE4 (open circles). Also shown on this graph are the selectivity thresholds, s = 1.4; s = 1.5 and s = 1.6 as guides for the eyes.

[0095] There [ Fig.11 ] shows that high selectivity values ​​are obtained both with examples E1 to E5, E7, E9 to E12, E15 and E16 comprising only one layer 1002a of doped tungsten oxide in the first dielectric module 1002, and with examples E6, E8, E13 to E14 and E17 comprising two layers 1002a, 1004a of doped tungsten oxide located in the first 1002 and second 1004 dielectric modules.

[0096] As illustrated in the [ Fig.11], examples E1 to E17 and counterexamples CE1 to CE7 can be divided into two groups. The group of examples E1 to E11 and counterexamples CE1 and CE2 for which the light transmission is about 70% and the group of examples E12 to E17 and counterexamples CE3 and CE4 for which the light transmission is greater than 78%.

[0097] For the first group, i.e. the examples and counterexamples with a light transmission of approximately 70%, the [ Fig.11 ] clearly illustrates a reduction in the solar factor for the examples according to the invention in comparison with the counter-examples CE1 and CE2. In particular, the selectivity of the examples is greater than 1.50 or even 1.55.

[0098] Counterexample CE2 has a selectivity greater than 1.50 but less than 1.55. This counterexample CE2 includes a titanium oxide layer placed above and in contact with the metal functional layer. The corresponding examples E9 to E11 have a lower solar factor value and therefore a higher selectivity.

[0099] For the second group, i.e. examples and counter-examples with a light transmission greater than 78%, the [ Fig.11 ] clearly illustrates a reduction in the solar factor for the examples according to the invention in comparison with the counter-examples CE3 and CE4. In particular, the selectivity of the examples is greater than 1.40 or even 1.50.

[0100] Counterexample CE4 has a selectivity greater than 1.40 but less than 1.50. This CE4 counterexample includes a titanium oxide layer placed above and in contact with the metal functional layer. The corresponding examples E15 to E17 have a lower solar factor value and therefore a higher selectivity.

[0101] The light reflection values ​​on the inner face, Rint, and on the outer face, Rext, are represented on the [ Fig.12 ] for examples E1 to E17 (filled circles) and counter-examples CE1 to CE 4 (empty circles).

[0102] There [ Fig.12] shows that the examples according to the invention have levels of reflection on the internal face and on the external face which are lower, if not equivalent, to those of the counter-examples for comparable light transmission values. In other words, the invention also makes it possible to reduce light reflection while preserving the same level of light transmission.

[0103] The values ​​of the color parameters a*, b* are represented on the [ Fig.13 ] for examples E1 to E17 (filled figures) and counter-examples CE1 to CE 4 (empty figures). The transmission color parameters a*T, b*T are represented by circles, the reflection parameters on the outer face a*Rext, b*Rext are represented by triangles, and the reflection parameters on the inner face a*Rint, b*Rint are represented by squares.

[0104] In transmission, the examples according to the invention, in particular most of the examples which only comprise a layer 1002 of doped tungsten oxide in the first dielectric module 1002, have a lower color parameter b*. The counter-examples have a color shifted towards yellow.

[0105] In external face reflection, the examples according to the invention have a lower color parameter a*Rext. The examples which only comprise a layer 1002 of doped tungsten oxide in the first dielectric module 1002 also have a higher color parameter b*Rext, i.e. approaching zero. The counter-examples have a red-shifted color.

[0106] In internal face reflection, the examples according to the invention have a lower a*Rint color parameter and a higher b*Rext color parameter. The counterexamples have a color shifted towards violet.

[0107] These examples very clearly illustrate the advantages of the substrates of the invention, namely that they have a reduced solar factor, higher selectivity, and have a more neutral color.

Claims

1. A transparent substrate (1000) provided with a functional stack (1001) of thin layers on at least one of its faces (1000a, 1000b), said functional stack (1001) comprising, starting from the substrate (1000): - at least one metallic functional layer (1003) placed between two dielectric modules (1002, 1004) of thin layers, and wherein at least one of the dielectric modules (1002, 1004) of thin layers comprises a layer (1002a, 1004a) of tungsten oxide, and the tungsten oxide comprises at least one doping element selected from the chemical elements of group 1 according to the IUPAC nomenclature.

2. The substrate (1000) according to claim 1, wherein the optical refractive index of the tungsten oxide layer (1002a, 1003a) is decreasing monotonically with the wavelength from a maximum value greater than 2.4 at 350 nm up to a minimum value between 600 nm and 900 nm so that the difference between the maximum value and the minimum value is greater than 0.8, preferably than 1.0, or even than 1.4.

3. The substrate (1000) according to either one of claims 1 to 2, wherein the optical extinction coefficient of the tungsten oxide layer (1002a, 1004a) is less than 0.2 at 500 nm and less than 2 at 1200 nm.

4. The substrate (1000) according to any one of claims 1 to 3, wherein the tungsten oxide layer (1002a, 1004a) comprises the doping element or several doping elements in proportions 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.

5. The substrate (1000) according to any one of claims 1 to 4, wherein the tungsten oxide layer (1002a, 1004a) comprises at least one doping element selected from hydrogen, lithium, sodium, potassium and cesium.

6. The substrate according to claim 2, wherein the tungsten oxide layer (1002a, 1004a) 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.

7. The substrate (1000) according to any one of claims 1 to 3, wherein the tungsten oxide layer (1002a) is comprised in the dielectric module (1002) of layers located under the metallic functional layer (1003), between said substrate (1000) and said metallic functional layer (1003).

8. The substrate (1000) according to any one of claims 1 to 3, wherein each dielectric module (1002, 1004) of layers comprises a layer (1002a, 1004a) of tungsten oxide.

9. The substrate (1000) according to any one of claims 1 to 5, wherein the physical thickness of the tungsten oxide layer(s) (1002a, 1004a) is between 2 nm and 50 nm, in particular between 5 nm and 30 nm, preferably between 5 nm and 20 nm.

10. The substrate (1000) according to any one of claims 1 to 6, wherein the functional stack (1001) of layers further comprises a blocking metal overlayer (6001), preferably based on nickel and chromium alloy, located above and in contact with the metallic functional layer (1003) and / or a metallic blocking underlayer (6002), preferably based on nickel and chromium alloy, located below and in contact with the metallic functional layer (1003).

11. The substrate (1000) according to any one of claims 1 to 7, wherein the functional stack of layers further comprises an overlayer (7001) of titanium oxide located above, preferably in contact with, the metallic functional layer (1003), said overlayer preferably having a physical thickness of at least 5 nm.

12. The substrate (1000) according to any one of claims 1 to 8, wherein the functional stack (1001) of layers comprises a layer with a refractive index less than 2.45 at 550 nm, said layer being comprised in the dielectric module (1004) of layers forming the upper part of the functional stack (1001) starting from the substrate (1000).

13. The substrate (1000) according to any one of claims 1 to 12, wherein the metallic functional layer (1003) is a silver-based layer.

14. A glazing comprising at least two transparent substrates, one of the substrates being a substrate according to any one of claims 1 to 13 arranged such that the functional stack of layers is located facing two and / or facing three of said glazing.

15. A method for manufacturing a transparent substrate according to any one of claims 1 to 13, such that the tungsten oxide layer is deposited by a magnetron sputtering method using a tungsten oxide target doped using a chemical element chosen from the chemical elements of group 1 according to the IUPAC nomenclature.