EP2200947A2

EP2200947A2 - Material with photocatalytic properties

Info

Publication number: EP2200947A2
Application number: EP08835279A
Authority: EP
Inventors: Sophie Besson; François-Julien VERMERSCH; Arnaud Huignard
Original assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Current assignee: Saint Gobain Glass France SAS; Compagnie de Saint Gobain SA
Priority date: 2007-09-10
Filing date: 2008-09-09
Publication date: 2010-06-30
Also published as: WO2009044066A3; CN101801868A; FR2920762B1; US20100304059A1; JP2010538808A; FR2920762A1; CN101801868B; WO2009044066A2; KR20100065322A

Abstract

The invention relates to a material comprising a substrate covered over at least a part of at least one face thereof by a coating comprising photocatalytic titanium oxide, characterised in that said substrate and/or a coating arranged between said substrate and said coating comprising photocatalytic titanium oxide has at least one compound which can convert radiation the wavelength of which is in the visible range, or the infrared range into a radiation the wavelength of which is in the ultraviolet range.

Description

MATERIAL WITH PHOTOCATALYTIC PROPERTIES

The present invention relates to the field of photocatalytic materials, in particular materials having photocatalytic activity when subjected to low energy radiation.

Titanium oxide, in particular when it is crystallized in anatase form, has photocatalytic properties: excited by radiation whose wavelength is less than or equal to 380 nm, thus located in the ultraviolet range, it has the particularity of catalyzing radical oxidation reactions. Under the effect of the radiation, an electron-hole pair is created, which contributes to degrade the organic compounds possibly present on the surface of the titanium oxide. A material comprising a coating based on photocatalytic titanium oxide thus has self-cleaning properties, antibacterial, or purification of liquid or gaseous effluents polluted particularly appreciable. Such materials are known from, for example, EP-A-0 850 204.

A disadvantage of titanium oxide is that its photocatalytic activity is mainly triggered by high energy radiation, in this case ultraviolet radiation. This disadvantage is not detrimental when the material is exposed to solar radiation, since the latter comprises components in the ultraviolet, but becomes when the material is located in a place little subject to ultraviolet radiation (part of a dwelling, passenger compartment, tunnel ...). Most of the solar ultraviolet radiation is absorbed by the glazing, while artificial light sources emit only slightly in the ultraviolet. It is therefore desirable to develop photocatalytic layers whose activity can be high for wavelengths located in the visible range, or even the infrared. Solutions have been proposed to this problem, which consist in particular in doping the crystal lattice of titanium oxide with various atoms (for example nitrogen) in order to modify the gap between the valence and conduction bands of titanium oxide. Such solutions are for example described in application WO2005 / 102953.

These solutions are however not without drawbacks, because the material thus doped has an absorption in the visible range, and therefore a certain coloring. Doping also creates defects in the structure of the titanium oxide that result in a decrease in quantum efficiency. The object of the invention is to propose a titanium oxide-based photocatalytic material whose photocatalytic activity can be high even in the absence of ultraviolet radiation while being free of the above-mentioned drawbacks.

To this end, the subject of the invention is a material comprising a substrate coated on at least a part of at least one of its faces with a coating comprising photocatalytic titanium oxide. The material is characterized in that said substrate and / or a coating disposed between said substrate and said coating comprising photocatalytic titanium oxide comprises at least one compound capable of converting radiation whose wavelength is within the range visible or infrared radiation whose wavelength is in the field of ultraviolet.

The compound capable of converting a radiation whose wavelength is comprised in the visible or infrared range into a radiation whose wavelength is in the ultraviolet range will be called a "length converter compound". wave "throughout the text as well as in the claims. It is understood that this term can not be interpreted otherwise. In particular, it can not be interpreted as covering compounds that are not capable of emitting ultraviolet radiation, or as covering compounds capable of converting radiation included in the ultraviolet range into radiation included in the visible range or infrared.

For the purposes of the present invention, the ultraviolet range comprises wavelengths of between 100 and 400 nm. The visible domain includes wavelengths between 400 and 800 nm. The infrared range includes wavelengths between 800 nm and 12 micrometers.

The fluorescent compounds have the particularity, when they are subjected to radiation of a given wavelength, to re-emit a second radiation of higher wavelength, and therefore of lower energy than that of the incident radiation.

Recently, however, compounds have been discovered capable of emitting higher energy radiation than incident radiation. This phenomenon, which is explained by successive absorptions of several photons by the same ion or by absorptions by different ions followed by energy transfers between said ions, is extremely rare. In fact, only a few ions, in particular rare earth ions or transition metal ions, occur. In addition, the associated luminescence efficiency is generally very low because the probability of occurrence of the phenomenon is itself very low. Among these compounds, some convert infrared radiation into visible radiation, and find applications in the field of imaging, photovoltaics and so on. Other, rarer, and which are called "compounds wavelength converters" in the context of the invention, are capable of converting visible or infrared radiation into ultraviolet radiation.

In the material according to the invention, such a compound is present under the photocatalytic coating based on titanium oxide, either within an underlayer or within the substrate itself. The operating principle of the invention can be schematically presented in the following manner: the titanium oxide being transparent to most of the visible or infrared radiation, this radiation passes through the photocatalytic coating, then is partially absorbed by the converter compound of wavelengths. This compound then isotropically re-emits ultraviolet radiation, part of which is absorbed by the titanium oxide. Titanium oxide, excited by this ultraviolet radiation, then fully plays its role of photocatalyst. It is important that the wavelength converting compound is disposed under the coating photocatalytic and not above because the organic soils must be in contact with the titanium oxide.

The substrate is preferably of glass (in particular of silico-soda-lime or borosilicate glass), ceramic, glass-ceramic or polymeric material. It is advantageously flat or curved. The substrate is preferably at least partially transparent. The substrate may also be fibrous, for example a mineral wool mat (glass wool or rock wool), a felt or fiberglass or silica cloth. When the substrate is of polymeric material, it is preferably polycarbonate, polymethyl methacrylate (PMMA), polyvinyl chloride (PVC), polyethylene, polypropylene.

The titanium oxide is preferably at least partially crystallized in the anatase form because it is the most active crystalline form. The rutile form, alone or mixed with the anatase form, is also interesting.

The coating comprising titanium oxide may consist of titanium oxide: it may be for example a coating obtained by processes using organometallic precursors of titanium oxide in liquid, solid form. or gaseous, as sol-gel type processes or CVD (chemical vapor deposition, possibly assisted by plasma, preferably at atmospheric pressure). It may also be coatings obtained by physical vapor deposition (PVD) techniques such as cathode sputtering, in particular assisted by magnetic field (magnetron process), or evaporation. Techniques for deposition of titanium oxide by magnetron method are for example described in application WO 02/24971. In the case of a magnetron deposition, sublayers promoting the epitaxial growth of TiO ₂ anatase, in particular BaTiO ₃ or SrTiO ₃ , may be previously deposited, as described in application WO 2005/040058.

The coating comprising titanium oxide may also comprise particles of titanium oxide dispersed in an organic binder and / or mineral, especially a mineral binder obtained by sol-gel route. The particles are preferably of nanometric size (nanoparticles), in particular of average diameter between 0.5 and 100 nm, especially between 1 and 80 nm. They generally consist of clusters of grains or elemental crystallites of diameter between 0.5 and 10 nm. The particles are preferably at least partly crystallized in the anatase form. The binder is preferably inorganic so as not to be degraded by the photocatalytic activity of the titanium oxide. It is preferably based on silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), or any of their mixtures. The coating comprising titanium oxide is advantageously obtained by sol-gel, for example by laminar coating, spin-coating, or cell-coating, solutions comprising a precursor of the binder (usually an organometallic compound) and particles. of titanium oxide. The binder is preferably a silica binder (SiO ₂ ), which can be easily obtained sol-gel from silicon alkoxides (for example TEOS, tetraethoxysilane). This binder, especially the silica binder, can advantageously be mesoporous, in the sense that it contains generally ordered pores whose size is between 2 and 50 nm. Such a binder is for example known from the application WO 03/087002, and makes it possible to obtain particularly high photocatalytic activities.

The thickness of the photocatalytic coating is preferably greater than or equal to 5 nm, especially 10 nm and / or less than or equal to 1 micrometer, especially 50 nm when the coating is made of titanium oxide. Large thicknesses lead indeed to a reflection of the high visible radiation and therefore undesirable in some applications where the optical appearance is important (especially glazing). It is possible to insert under the photocatalytic coating at least one layer whose function is to reduce the luminous reflection of the material and / or to make the coloration in reflection more neutral. It may in particular be the layers or stacks of layers described in the application WO 02/24971. The photocatalytic coating may also itself be included in an antireflection stack, as described in application WO 2005/110937.

The coating comprising the titanium oxide is preferably in contact with the air, therefore the only layer deposited on the substrate or the last layer of the stack. The coating comprising the titanium oxide may, however, itself be coated with a very thin, preferably non-covering, layer of an oxide comprising silicon, in particular and preferably based on silica (SiO ₂ ). This layer makes it possible to confer photo hydrophilic properties. induced prolonged even in the dark and / or improve the abrasion resistance of the stack. Its thickness is preferably less than or equal to 5 nm. The application WO 2005/040056 describes such overlays.

The coating comprising the titanium oxide may also be coated with a very thin metal layer, preferably non-covering (for example in the form of micro-grid), in particular based on metal chosen from silver, platinum, palladium. This electroconductive layer makes it possible to avoid recombinations of the electron-hole pairs produced during the activation of the titanium oxide. The or each wavelength converting compound preferably comprises at least one rare earth ion or a transition metal inserted in a mineral matrix. Mineral matrices have higher durability than organic matrices. Rare earth ions (lanthanides) are preferred because they have the highest conversion efficiencies.

The ions of a rare earth or of a transition metal are preferably chosen among the ions Yb ³⁺ , Tb ³⁺ , Tm ³⁺ , Eu ³⁺ , Eu ²⁺ , Er ³⁺ , Pr ³⁺ , Nd ³⁺ , Dy ³⁺ , Ho ³⁺ , Ti ²⁺ , Ni ²⁺ , Mo ³⁺ , Os ⁴⁺ , Re ⁴⁺ , Mn ²⁺ , Cr ³⁺ . It may be preferable to use two different ions, one absorbing visible or infrared radiation, the other retransmitting ultraviolet radiation after energy transfer. The pairs formed by the Yb ³⁺ ion (which absorbs for wavelengths close to 980 nm) with Tb ³⁺ or Tm ³⁺ or Er ³⁺ make it possible, for example, to obtain high luminescence yields. The pair of ions Pr ³ VNd ³⁺ is also interesting. In the case where an ion of a single nature is used, the Pr ³⁺ or Er ³⁺ ions are preferred. It may be advantageous in applications of the glazing type to choose wavelength converting compounds which absorb infrared radiation and not visible radiation, which is the case, for example, of compounds containing a Yb ³⁺ / Tb ³⁺ couple. or Tm ³⁺ or Er ³⁺ described previously.

The mineral matrix can be amorphous (it can for example be a glass), or crystallized. The advantage of choosing an amorphous matrix is that it can contain large amounts of ions. The crystallized matrices are however preferred because the environment of the ions (and therefore their emission / absorption spectrum) is perfectly controlled. In addition, the amorphous matrices generally contain more structural defects, which can lead to the creation of intermediate energy levels and thus facilitate deexcitations by non-radiative (for example by phonon emission) or radiative transfer, but low energy transfers. In the case where the matrix is crystallized, the active ion must be able to be inserted into the crystal lattice in place of an ion of the matrix. As a result, matrices containing yttrium (Y), lanthanum (La), gadolinium (Gd) or lutetium (Lu) atoms are preferred because it has been observed that rare earth ions can easily be substitute for these ions within a crystal lattice. The phonon frequency of the crystalline matrix is preferably at least four times lower than the emission frequency so as to avoid non-radiative transfer deexcitations. As a result, the preferred crystalline matrices are chosen from halides (in particular fluorides, but also bromides or chlorides) or oxides. The inorganic matrix is selected for example (non-limiting manner) from NaYF _4, Y ₂ O _3, Y ₂ SiO _5, LaPO _4, TeO _2, or Y ₃ Al ₅ O ₂ (YAG). The quantity of doping ions is generally between 0.01 and 50% (in moles relative to the ions to which they substitute), more particularly between 5 and 50% when it is about Yb ³⁺ and between 0, 01 and 10% for the other doping ions mentioned above.

The following wavelength-converting compounds proved to be particularly effective: doped TeO ₂ Pr ³ VNd ³⁺ , doped Y ₂ SiO ₅ Pr ³⁺ , Y ₃ Al ₅ O ₁₂ doped Er ³⁺ , CaF ₂ doped Yb ³ VTb ³⁺ , Y ₂ O ₃ doped Yb ³ VTb ³⁺ , NaYF ₄ doped Yb ³ VTb ³⁺ . By "doped" is meant that the matrix comprises the ions mentioned, without necessarily prejudging the amount of ions present, which can be relatively high, as indicated above.

The wavelength converter compound may be included in the substrate. The latter can thus be a glass-ceramic comprising crystals and an amorphous binder, at least a portion of said crystals constituting wavelength converting compounds. Vitro-ceramics based on SiO ₂ / Al ₂ O ₃ / CaF ₂ in which crystals of CaF ₂ are formed, which crystals include in their crystal structure Yb ³⁺ and Tb ³⁺ ions are thus capable of absorbing radiation whose wavelength is 980 nm to re-emit radiation centered on the 380 nm wavelength.

The wavelength converting compound may alternatively or cumulatively be included in a coating disposed between the substrate and the coating comprising photocatalytic titanium oxide. This coating is called in the following text "coating wavelength converter".

The wavelength converting compound can be included in the coating in the form of particles dispersed in a mineral or organic binder. These particles are preferably less than 500 nm in size, in particular 300 nm and even 200 nm or 100 nm so as not to generate spurious diffusions likely to affect the transparency of the material. Diffusion can also be avoided by choosing a binder whose refractive index is equal to that of the particles. The amount of particles of the energy converting compound within the binder is at least 1% (by weight) and preferably greater than 5%. The thickness of the coating is preferably at least equal to 100 nm, preferably greater than or equal to 500 nm and even greater than or equal to 1 μm and / or less than or equal to 10 μm, or even 5 μm.

The organic binder can be, for example, acrylic, epoxy, cellulosic or silicone type, the latter type being preferred because it is less sensitive to possible degradation by photocatalytic titanium oxide. If necessary, a barrier layer may be disposed between the wavelength converting coating and the photocatalytic coating to prevent degradation of the first coating by the second.

The inorganic binder can be, for example, a binder made of a material chosen from silica (SiO ₂ ), alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ) or a mixture thereof. This binder may in particular be obtained by a decomposition method of organometallic precursors or halides, for example a sol-gel type process, or plasma-assisted chemical vapor deposition at atmospheric pressure (APPECVD). The binder can also be an enamel or a glaze, obtained by melting a glass frit deposited for example by screen printing.

The wavelength converter coating may also consist of a wavelength converter compound. Unlike the mode of previously described embodiment, in which active particles were dispersed in a binder, the wavelength converting compound forms in itself the coating.

Various techniques are possible to deposit this coating: chemical vapor deposition (CVD) techniques, in particular assisted by plasma and at atmospheric pressure, sol-gel type techniques, or physical vapor deposition techniques, by example by sputtering, in particular assisted by magnetic field (magnetron process), or by evaporation. The coating, when the wavelength converting compound comprises an amorphous mineral matrix, may also be an enamel or a glaze obtained by melting a glass frit deposited for example by screen printing.

An underlayer or a stack of sub-layers reflecting at least a portion of the ultraviolet radiation is advantageously disposed between the wavelength converting coating and the substrate. The ultraviolet radiation emitted by the wavelength converting compound is indeed isotropic, so that a portion of this radiation is emitted towards the substrate and not towards the photocatalytic coating. Thanks to the underlayer reflecting at least a portion of the ultraviolet radiation, this portion of the emitted radiation is reflected to the photocatalytic coating, thereby increasing the activity of the latter. Stacks of sub-layers containing at least three layers having alternately low and high refractive indexes are preferred because they exhibit very low reflection in the visible range, but strong reflection in the ultraviolet range.

A preferred embodiment consists of a transparent silica-soda-lime glass substrate coated with a silica layer obtained by a sol-gel type process comprising particle-length wavelength converting compounds, this layer being itself even surmounted by a silica layer also obtained by a sol-gel type process and comprising crystallized titanium oxide particles in anatase form.

When the substrate contains alkaline ions (especially in the case of silico-soda-lime glass, which contains about 13% by weight of sodium oxide), these are likely to migrate, especially under the effect of temperature, in the layers that surmount the substrate. Since this migration is likely to cause a decrease in the luminescence efficiency of the wavelength converting compound, it is preferable to have an underlayer acting as a barrier to migration between the substrate and the wavelength converting coating. alkaline ions. Such an underlayer, which is otherwise known, may be, for example, SiO ₂ , Al ₂ O ₃ , SiO _x Cy, Si ₃ N ₄ , SnO ₂ etc.

The invention also relates to different products incorporating the material according to the invention. When the substrate is transparent, especially when it is made of soda-lime-silica glass, the material according to the invention can be incorporated into a glazing, for example single, multiple and / or laminated glazing, curved and / or tempered glazing, clear or tinted glazing. The material according to the invention can also be incorporated in a display screen, an aquarium, a greenhouse, indoor furniture, tiles, a mirror. In the latter case, the substrate may be a mirror comprising a transparent glass sheet on one side of which is deposited a layer of silver coated with a lacquer. The resulting mirror thus has self-cleaning and anti-fogging properties that are particularly appreciable, for example in a bathroom. The material according to the invention can also be used in eyewear. The material may also be used as tiling, in particular glass, for example as described in application FR-A-2868799.

The material according to the invention, in particular when the substrate is fibrous, may be incorporated into a filtration and purification structure for liquid or gaseous effluents.

Given its activation properties by visible or infrared radiation, the material according to the invention can be used in a dwelling or vehicle interior to degrade organic soil deposited on its surface. The invention will be better understood in the light of the embodiments described below, which illustrate the present invention without limiting it. EXAMPLE 1

In this example, the wavelength converting compound is included in an enamel coating. Micrometric particles of yttrium oxide (Y ₂ O ₃ ) doped with 18% (in mol) of ytterbium Yb ³⁺ and 2% of terbium Tb ³⁺ are dispersed in a glass frit with a low melting point ( 600 ⁰ C) based on silica and bismuth oxide. The paste obtained is deposited on a silico-soda-lime glass substrate by screen printing, then annealed for 6 minutes at a temperature of 680 ^° C. After cooling, a layer of titanium oxide of 50 nm thick is deposited with known manner by chemical vapor deposition (CVD), using titanium tetraisopropylate as a precursor.

The photocatalysis process is activated by excitation by a lamp emitting mainly between 900 and 1000 nm. Under these radiations, the wavelength converting material emits at 380 nm, wavelength which triggers the photocatalytic effect.

EXAMPLE 2

This example illustrates an embodiment in which the wavelength converting compound is included in a coating by being dispersed in a sol-gel silica binder.

To 4 ml of a colloidal solution of nanoparticles of NaYF ₄ : 20 mol% Yb ³⁺ , 2 mol% Er ³⁺ is added 1 ml of sol-gel silica sol. The diameter of the nanoparticles is 30 nm ± 10 nm, the mass concentration of the colloidal solution in nanoparticles being 10%. The sol-gel silica sol is obtained by hydrolysis (duration = 4 hours) of a mixture of tetraethoxysilane (TEOS), absolute ethanol and an aqueous solution of pH = 2.5 acidified with the aid of hydrochloric acid, the respective molar ratios of the various constituents of the mixture being 1: 4: 4. The solution containing nanoparticles of NaYF ₄ : 20% Yb, 2 mol% Er ³⁺ and silica sol-gel is then deposited by spin-coating on a sand-calcium-silicate glass substrate previously cleaned with the aid of a aqueous solution containing 2% by weight of RBS (surfactant). The coating obtained is then dried at 100 ^° C. for 1 hour, then annealed at 450 ^° C. for 3 hours. The thickness of the coating is 450 nm, its light transmission being greater than 80% over the entire visible spectrum. At the end of these steps, a photocatalytic coating based on TiO ₂ nanoparticles dispersed in a mesoporous silica sol-gel binder is deposited. To do this, 22.3 ml of tetraethoxysilane, 22.1 ml of absolute ethanol and 9 ml of HCl in demineralized water are mixed in a first step until the solution becomes clear (pH 1, 25), then the resulting solution is placed at 60 ° C for 1 h. In a second step, an organic structuring agent, in the form of a solution of a polyoxyethylene-polyoxypropylene block copolymer marketed by BASF under the trade name Pluronic PE6800 (molar mass 8000), is added to the soil obtained above in proportions such as the molar ratio PE6800 / Si = 0.01. This is achieved by mixing 3.78 g of PE6800, 50 ml of ethanol and 25 ml of the sol. Crystallized TiO ₂ nanoparticles in the anatase form and approximately 50 nm in size are added to the liquid composition thus obtained before the sample deposition, in an amount such that the Ti / Si atomic ratio is equal to 1. The deposit is done by spin-coating. The samples are then subjected to heat treatment at 250 ^° C. for 2 hours in order to consolidate the mesoporous coating and to evacuate the solvent and the organic structuring agent. The pores of the coating thus formed have a size of 4-5 nm.

The photocatalysis process is activated by excitation by a lamp emitting mainly between 900 and 1000 nm. Under this radiation, the wavelength converting material emits at 380 nm, a wavelength that triggers the photocatalytic effect.

EXAMPLE 3

In this example, the wavelength converting compound is included in the substrate itself.

The substrate is a vitroceramic obtained by ceramizing a mother glass of molar composition SiO ₂ (47%) / Al ₂ O ₃ (19%) / CaF ₂ (28%) TbF ₃ (2%) / YbF ₃ (3%). It may be thought that the wavelength converting compound consists of a CaF ₂ matrix doped with Tb ³⁺ and Yb ³⁺ ions.

On this glass-ceramic substrate is deposited a TiO ₂ coating with a thickness of 50 nm. This coating is deposited by chemical vapor deposition (CVD) using titanium tetraisopropoxide (TiPt) at 500 ^° C.

Claims

1. Material comprising a substrate coated on at least a portion of at least one of its faces with a coating comprising photocatalytic titanium oxide, characterized in that said substrate and / or a coating disposed between said substrate and said coating comprising photocatalytic titanium oxide comprises at least one compound capable of converting radiation whose wavelength is in the range of visible or infrared into radiation whose wavelength is included in the ultraviolet domain (wavelength converter compound).

2. Material according to claim 1, such that the substrate is glass, ceramic, glass-ceramic or polymeric material.

3. Material according to one of the preceding claims, such that the titanium oxide is at least partially crystallized in the anatase form.

4. Material according to one of the preceding claims, such that the coating comprising titanium oxide is made of titanium oxide.

5. Material according to one of claims 1 to 3, such that the coating comprising titanium oxide comprises titanium oxide particles dispersed in an organic binder and / or mineral, including a mineral binder obtained by a sol -gel.

6. Material according to one of the preceding claims, such that the at least one wavelength converting compound comprises at least one ion of a rare earth or of a transition metal inserted in a mineral matrix.

7. Material according to the preceding claim, such that the at least one ion of a rare earth or of a transition metal is chosen from ions Yb ³⁺ , Tb ³⁺ , Tm ³⁺ , Eu ³⁺ , Eu ^{2 +} , Er ³⁺ , Pr ³⁺ , Nd ³⁺ , Dy ³⁺ , Ho ³⁺ , Ti ²⁺ , Ni ²⁺ , Mo ³⁺ , Os ⁴⁺ , Re ⁴⁺ , Mn ²⁺ , Cr ³⁺ .

8. Material according to one of claims 6 or 7, such that the mineral matrix is crystallized.

9. Material according to one of claims 6 to 8, such that the mineral matrix is a halide, especially a fluoride, or an oxide.

10. Material according to the preceding claim, such that the inorganic matrix is selected from NaYF _4, Y ₂ O _3, Y ₂ SiO _5, LaPO _4, TeO ₂ or Y ₃ AI ₅ O _2.

11. Material according to one of claims 6 to 10, such that the wavelength converting compound is selected from doped TeO ₂ Pr ³ VNd ³⁺ , Y ₂ SiO ₅ doped Pr ³⁺ , Y ₃ AI ₅ O ₁₂ doped Er ³⁺ , CaF ₂ doped Yb ³ VTb ³⁺ , Y ₂ O ₃ doped Yb ³ VTb ³⁺ , NaYF ₄ doped Yb ³ VTb ³⁺

12. Material according to one of the preceding claims, such that the wavelength converting compound is included in the substrate.

13. Material according to the preceding claim, such that the substrate is a glass-ceramic comprising crystals and an amorphous binder, at least a portion of said crystals constituting wavelength converting compounds.

14. Material according to one of claims 1 to 11, such that the wavelength converting compound is included in a coating (wavelength converter coating).

15. Material according to the preceding claim, such that the wavelength converting compound is included in the coating in the form of particles dispersed in a mineral or organic binder.

16. The material of claim 14, wherein the wavelength converting coating is comprised of a wavelength converting compound.

17. Material according to one of claims 14 to 16, such as an underlayer or a stack of sub-layers reflecting at least a portion of the ultraviolet radiation is disposed between the wavelength converting coating and the substrate.

18. Single, multiple and / or laminated glazing, curved and / or tempered glazing, clear or tinted glazing, display screen, aquarium, greenhouse, interior furniture, tiling, mirror, eyewear, incorporating the material according to the one of the preceding claims.