EP2694448A1

EP2694448A1 - Glass substrate with slightly rough layer

Info

Publication number: EP2694448A1
Application number: EP12718284.8A
Authority: EP
Inventors: Alexandre Popoff; Bernard Nghiem
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: 2011-04-04
Filing date: 2012-03-30
Publication date: 2014-02-12
Also published as: JP5992993B2; US20140116412A1; EA201391462A1; WO2012136919A1; EA025612B1; JP2014511817A; CN103459344B; MX347045B; MX2013011446A; FR2973366A1; BR112013023979A2; CN103459344A; KR20140009431A

Abstract

The invention relates to - a glass substrate, characterized in that it is provided with a layer constituted of crystallites of at least 25 nm, covered directly with a layer constituted of crystallites of at most 10 nm; - the process for manufacturing same; - the applications thereof in a photovoltaic cell electrode, as low-emissivity glazing or in solar control.

Description

LOW RUGGED LAYER VERRIER SUBSTRATE

The present invention relates to the coating of a rough inorganic layer and / or having surface irregularities with acute angles and / or spikes and deposited on a particular glass substrate, by an amorphous or nanocrystalline layer, in order to reduce or eliminate the surface roughness and / or rounding or softening surface irregularities.

The assembly constituted by the substrate and the layers is in particular transparent, the layers conferring on the whole of the properties for example optical (blur, diffusion, absorption of light, coloration ...) and / or thermal (low-emissivity, control solar -reflection of part of solar radiation -...) and / or electrical (conductivity ...) and / or catalytic (self-cleaning ...).

For example, the production of low-emissivity glazing for building or transport vehicle (automotive) applications requires the deposition of a transparent conductive oxide (TCO) layer on a substrate. glass. One commonly used route is to deposit fluorine doped tin oxide by chemical vapor deposition (CVD).

The disadvantage of the thermal CVD comes from the fact that, since the glass is hot, the layer obtained is generally well crystallized, that is to say predominantly contains relatively large crystallites, and thus has a non-zero roughness on the surface. Roughness here refers, in common, the height between the highest points of an irregular surface (vertices) and the lowest (valleys). This surface roughness results in a high blur value that is sought to avoid in certain applications, in which it is considered aesthetically unpleasant or visually troublesome.

In addition, the well-crystallized layer obtained has surface irregularities forming sharp-edged asperities which may hinder or even prevent cleaning of the surface.

In applications of photovoltaic cell electrode type, such asperities on the surface of a TCO layer can induce short-circuit phenomena with the absorbing active layer (amorphous silicon, CdTe ...) overlying. This results in a decrease in performance of the photovoltaic cell, especially through the reduction of the open circuit voltage. The inventors have therefore set themselves the objective of reducing or even eliminating the roughness of layers such as obtained on hot glass substrate by thermal CVD, and / or rounding or softening their surface irregularities at acute angles (forming points), possibly with maintenance. roughness.

This object is achieved by the invention, which relates to a glass substrate, characterized in that it is provided with a layer consisting of crystallites of at least 25 nm, directly covered with a layer consisting of crystallites of at most 10 nm. According to the invention, a layer consisting of crystallites of at least 25 nm, or at most 10 nm, is mainly composed of crystallites whose largest dimension is such. A layer consisting of crystallites of at least 25 nm results from thermal CVD deposition on glass usually at about 600 ° C.

The two layers of the glass substrate of the invention consist of identical or different materials.

The size of the crystallites is here determined from the X-ray diffraction measurements (XRD) carried out on the crystallized layers. The X-ray diffraction apparatus is used in theta-theta mode on a plane parallel to the surface of the sample. The calculation of the grain size uses the Scherrer relation (k = 0.9, instrumental width determined from the fundamental parameters) and all the widening of the peak is attributed to a size effect (Pearson VII type profile used). The indicated size is the minimum size for 25 nm, respectively maximum for 10 nm, among the sizes obtained for each of the diffraction peaks.

The thickness of the layer consisting of crystallites of at most 10 nm can reach values of 700 nm, or even up to 2 μηι.

The thickness of the crystallite layer of at least 25 nm is not limited; it is for example at most equal to 2, preferably 1, 5 μηη; and a minimum average thickness of the order of the size of the crystallites (from 25 nm) is conceivable.

According to other preferred characteristics of the glass substrate of the invention:

the thickness of the layer of crystallites of at most 10 nm is at most equal to 350, preferably 250 nm; the inventors have found that a maximum thickness of 350 nm of coating consisting of crystallites of at most 10 nm provides a desired effective smoothing of an underlying functional layer deposited by thermal CVD, by decreasing or even eliminating the surface roughness and / or rounding out small pointed growths with possible maintenance of the roughness in this case; this effect is still obtained at thicknesses of this layer of 100 nm, and even up to thicknesses of this layer of 10 or even 5 nm;

the glass substrate is directly covered with a barrier layer vis-à-vis the migration of alkali glass; the barrier layer is therefore under the layer consisting of crystallites of at least 25 nm, either directly or with the interposition of one or more other layers; the function of the barrier layer is to prevent the contamination of the upper layers by the sodium ions of the glass, when the glass is in particular conditions, especially at elevated temperature; it may consist of silica or silicon oxycarbide SiOC;

the layer of crystallites of at least 25 nm on the one hand, of at most 10 nm on the other hand, is a transparent oxide layer, electroconductive or not; examples of transparent conductive oxides Sn0 ₂ : F, SnO ₂ : Sb, ZnO: Al, ZnO: Ga, InO: Sn, ZnO: 1n, and examples of non-conductive transparent oxides Sn0 ₂ , ZnO, InO; the transparent oxide constituting these layers can be photocatalytic, such as Ti0 ₂ , that is to say have properties of radical oxidizing initiator under solar radiation (hydrocarbon degradation properties, self-cleaning).

The invention also relates to

a method of manufacturing a glass substrate defined above, in which the layers consisting of crystallites of at least 25 nm, respectively at most 10 nm, are formed by chemical vapor deposition at a temperature of the substrate relatively high (especially at least 500, preferably 550 ° C), respectively relatively low (in particular at least equal to 300 ° C and at most equal to 550, preferably 500 ° C);

the application of a glass substrate described above in a photovoltaic cell electrode, in which the layer composed of crystallites of at most 10 nm rounds and / or softens the surface irregularities with acute angles and / or spikes the layer consisting of crystallites of at least 25 nm, but without necessarily reducing its roughness, and is coated with amorphous or microcrystalline silicon as an absorbent;

applying a glass substrate described above in a photovoltaic cell electrode, wherein the crystallite layer of at most 10 nm has a flat surface (zero roughness), and is coated with CdTe as absorbent; the relatively conductive layer such as Sn0 ₂ : F consisting of crystallites of at least 25 nm is then covered with the layer of crystallites of at most 10 nm, necessarily non-conductive (in English "buffer layer"), such as Sn0 ₂ , which is advantageously flat and smooth because CdTe, absorbing relatively large amounts of light, does not require light trapping by the underlying layers; and

the application of a glass substrate described above as low-emission glazing in the building or for a transport vehicle, in household appliances such as oven door or heating layer structure, or in solar control on the face of glazing in contact with the external atmosphere, whose surface with reduced roughness or even zero, and / or rounded and / or softened asperities facilitates cleaning; let us mention as a solar control layer Sn0 ₂ : Sb.

The invention is now illustrated by the following embodiment.

EXAMPLE

Two chemical vapor phase depositions are successively carried out on a substrate 1 m wide.

The substrate consists of 4 mm thick float soda-lime glass sold under the registered trade name Planilux® by Saint-Gobain Glass France, provided with a 25 nm SiOC layer constituting a barrier against the migration of alkaline glass.

The first deposit is made under the following conditions:

Substrate temperature: 600 ° C,

Substrate running speed (direction perpendicular to the width): 12 m / min,

Flow rate of monobutyltin trichloride (MBTCL): 30 kg / h, Water flow rate: 7.5 kg / h,

Air flow (80% nitrogen, 20% oxygen by volume) total: 1,195 l / min.

A 400 nm thick layer consisting of Sn0 ₂ crystallites of at least 25-30 nm is obtained. The blur of the coated substrate is 17%.

The second deposit is made under the following conditions:

Substrate temperature: 450 ° C,

Substrate speed: 8 m / min,

Other conditions identical to those of the first deposit.

A second 150 nm thick layer consisting of Sn0 ₂ crystallites of about 6 nm is obtained. The blur of the substrate coated with the layers of the first and second deposits is 17.1%.

The layer of the second deposit maintained the properties of the substrate before it was deposited. The only modification was the smoothing of the surface facilitating its cleaning; it is found that a cloth-type cleaning means is no longer hooked by the asperities with sharp corners of the surface, which have been more or less covered and / or rounded.

Claims

Glass substrate, characterized in that it is provided with a transparent oxide layer consisting of crystallites of at least 25 nm, directly covered with a transparent oxide layer consisting of crystallites of at most 10 nm.

Glass substrate according to claim 1, characterized in that the thickness of the crystallite layer of at most 10 nm is at most equal to 350 nm.

Glass substrate according to one of the preceding claims, characterized in that the thickness of the crystallite layer of at most 10 nm is at most equal to 250 nm.

Glass substrate according to one of the preceding claims, characterized in that it is covered directly with a barrier layer vis-à-vis the migration of alkali glass.

Glass substrate according to one of the preceding claims, characterized in that the layer of crystallites of at least 25 nm on the one hand, of at most 10 nm on the other hand, is electroconductive and selected from Sn0 ₂ : F, Sn0 ₂ : Sb, ZnO: Al, ZnO: Ga, InO: Sn, ZnO: In, or non-electroconductive and selected from Sn0 ₂ , ZnO, InO, or photocatalytic and consisting of Ti0 ₂ .

A method of manufacturing a glass substrate according to one of the preceding claims, characterized in that said layers consisting of crystallites of at least 25 nm, respectively at most 10 nm, are formed by chemical vapor deposition at a relatively high substrate temperature, respectively relatively low.

Process according to Claim 6, characterized in that the relatively high substrate temperature is at least 500, preferably 550 ° C.

Process according to one of Claims 6 or 7, characterized in that the temperature of the relatively weak substrate is at least 300 ° C and at most 550, preferably 500 ° C.

Application of a glass substrate according to one of claims 1 to 5 in a photovoltaic cell electrode, wherein the crystallite layer of at most 10 nm rounds and / or softens the acute angle surface irregularities and / or in points of the layer consisting of crystallites of at least 25 nm, and is coated with amorphous or microcrystalline silicon as an absorbent.

Application of a glass substrate according to one of Claims 1 to 5 in a photovoltaic cell electrode, in which the layer consisting of crystallites of at most 10 nm has a flat surface and is coated with CdTe as an absorbent .

Application of a glass substrate according to one of claims 1 to 5 as low-emissive glazing in the building or for a transport vehicle, in the household appliance as oven door or heating layer structure, or in solar control on the glazing face in contact with the outside atmosphere.