Solar Glass And Method For Its Production

Abstract

A solar glass is specified. In an embodiment a solar glass includes a glass substrate and a layer system arranged on the glass substrate, wherein the layer system includes a base layer comprising one or more first dielectric layers, a first silver layer arranged on the base layer, an absorber layer arranged on the first silver layer, the absorber layer comprising a metal or metal alloy, an aluminum oxynitride layer arranged on the absorber layer, an intermediate layer arranged on the aluminum oxynitride layer, the intermediate layer comprising one or more second dielectric layers, a second silver layer arranged on the intermediate layer and a cover layer arranged on the second silver layer, the cover layer comprising one or more third dielectric layers, and wherein the absorber layer has a spatially varying thickness, a spatially varying material composition and/or a spatially varying surface coverage density in at least one direction.

Claims

1-18. (canceled)

19. A solar glass comprising: a glass substrate; and a layer system arranged on the glass substrate, the layer system comprising: a base layer comprising one or more first dielectric layers; a first silver layer arranged on the base layer; an absorber layer arranged on the first silver layer, the absorber layer comprising a metal or metal alloy; an aluminum oxynitride layer arranged on the absorber layer; an intermediate layer arranged on the aluminum oxynitride layer, the intermediate layer comprising one or more second dielectric layers; a second silver layer arranged on the intermediate layer; and a cover layer arranged on the second silver layer, the cover layer comprising one or more third dielectric layers, wherein the absorber layer has a spatially varying thickness, a spatially varying material composition and/or a spatially varying surface coverage density in at least one direction.

20. The solar glass according to claim 19 wherein a g-value of the solar glass has a maximum value g.sub.max at a first position and a minimum value g.sub.min at a second position, and wherein g.sub.maxg.sub.min0.05.

21. The solar glass according to claim 20, where g.sub.maxg.sub.minis 0.2.

22. The solar glass according to claim 19, wherein a g-value of the solar glass varies in a range between 0.05 and 0.45.

23. The solar glass according to claim 19, wherein a light transmission L.sub.t of the solar glass varies in a range between 0 and 0.8.

24. The solar glass according to claim 19, wherein the absorber layer has a thickness between 0.5 nm and 50 nm.

25. The solar glass according to claim 19, wherein the absorber layer comprises NiCr.

26. The solar glass according to claim 19, wherein the solar glass is a component of a window, a facade element or a vehicle pane.

27. The solar glass according to claim 19, wherein a thickness, a surface coverage density and/or a material composition of the absorber layer is not constant over the entire surface of the solar glass.

28. A method for producing the solar glass according to claim 19, the method comprising: producing the layer system by sputtering.

29. The method according to claim 28, wherein sputtering is performed in a sputtering system in which the glass substrate is transported while sputtering, and wherein a transport speed of the glass substrate varies while sputtering to produce the spatially varying thickness of the absorber layer. 3o. (New) The method according to claim 28, wherein sputtering is performed in a sputtering system in which the glass substrate is transported while sputtering, and wherein electrical power while sputtering of the absorber layer is varied over time to produce the spatially varying thickness of the absorber layer.

31. The method according to claim 28, wherein sputtering is performed in a sputtering system which, in order to produce the spatially varying thickness of the absorber layer, has at least one aperture between a cathode provided for sputtering the absorber layer and the glass substrate.

32. The method according to claim 28, wherein sputtering is performed in a magnetron sputtering system, and wherein an inhomogeneous magnetic field is used to generate the spatially varying thickness of the absorber layer.

33. The method according to claim 28, wherein a spatially inhomogeneous process gas is used for sputtering the absorber layer.

34. The method according to claim 28, wherein a cathode whose material composition varies in one direction is used for sputtering the absorber layer.

35. The method according to claim 28, further comprising, before applying the absorber layer, applying a mask layer to the glass substrate in order to produce a spatially varying surface coverage density of the absorber layer, wherein the mask layer has a spatially varying surface coverage density.

36. The method according to claim 35, wherein the mask layer is a point mask or a line mask.

37. The method according to claim 36, wherein the mask layer is a point mask comprising mask dots having a size between 0.5 mm and 3 mm.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The invention is explained in more detail in the following on the basis of exemplary embodiments in connection with FIGS. 1 to 3.

[0040] In the Figures:

[0041] FIG. 1 shows a schematic representation of a cross-section through a solar glass with a layer system according to an exemplary embodiment;

[0042] FIG. 2A is a top view of an example of an exemplary embodiment of the solar glass;

[0043] FIG. 2B shows a course of the thickness dA of the absorber layer in the vertical direction z in an exemplary embodiment;

[0044] FIG. 2C shows a course of the nickel concentration c.sub.Ni of the absorber layer in the vertical direction z in a further exemplary embodiment;

[0045] FIG. 3A shows the solar glass in an intermediate step of an exemplary embodiment of the method for producing the solar glass; and

[0046] FIG. 3B shows a course of the surface coverage density A of the absorber layer in the vertical direction z in an exemplary embodiment.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0047] Like or likely acting components are marked with the same reference signs in the figures. The components shown and the proportions of the components to each other are not to be regarded as true to scale.

[0048] The solar glass shown in FIG. 1 has a glass substrate 1, which may in particular be a float glass pane. On the glass substrate 1 a layer system 10 is applied, which serves in particular to protect against solar radiation.

[0049] The layer system 10 comprises a base layer 2 applied to the substrate 1, which is formed from several dielectric layers 21, 22, 23. The first layer on the substrate 1 in the growth direction of the layer system 10 is an aluminum oxynitride layer 21, which has a thickness between 10 nm and 17 nm, for example. The aluminum oxynitride layer 21 functions advantageously as a diffusion barrier which reduces diffusion of components of the glass substrate 1, for example sodium, into the layer system 10 and diffusion of components of the layer system 10 into the glass substrate 1. This is followed by a layer 22 of SnO.sub.2, which can have a thickness between 0 nm and 15 nm. The uppermost layer of the base layer 2 is a ZnO:Al layer 23, which can have a thickness between 5 nm and 30 nm, for example.

[0050] On top of the cover layer 23 of base layer 2 a first silver layer 3 has been grown, which for example has a thickness between 7 nm and 12 nm. The silver layer 3 is a first of two optical functional layers 3, 7, which serve in particular for the reflection of heat radiation.

[0051] The first silver layer 3 is followed in the direction of growth by a metallic absorber layer 4, which consists of a metal or a metal alloy and does not contain any silver. In particular, the absorber layer may be directly adjacent to the silver layer 3. The absorber layer is preferably a NiCr layer. For example, the absorber layer may contain 80% Ni and 20% Cr.

[0052] In the layer system described herein, the absorber layer 4 is produced in such a way that it has a spatially varying thickness, a spatially varying surface coverage density and/or a spatially varying material composition in at least one direction. In this way, the g-value and the light transmission L.sub.T are advantageously varied in at least one direction of the solar glass.

[0053] The absorber layer 4 is followed in the growth direction by a layer of aluminum oxynitride, which preferably directly adjoins the absorber layer 4. The layer 5 of aluminum oxynitride preferably has an oxygen content between o and 30% and a thickness of, for example, 5 nm to 27 nm. Layer 5 of aluminum oxynitride protects the absorber layer 4 advantageously against corrosion, especially oxidation. This has the advantage that the purely metallic character of the absorber layer 4 is retained even if the layer system 10 is subjected to a temperature treatment.

[0054] Layer 5 of the aluminum oxynitride is followed by an intermediate layer 6, which is formed by several dielectric layers 61, 62, 63, 64, 65, 66.

[0055] In the exemplary embodiment, the intermediate layer 6 contains, in the growth direction, a ZnO:Al layer 61 with a thickness of 10 nm to 17 nm, a SnO.sub.2 layer 62 with a thickness of 8 nm to 13 nm, a SiO.sub.xN.sub.y layer 63 with a thickness of 7 nm to 12 nm, an AlO.sub.xN.sub.y layer 64 with a thickness of 10 nm to 17 nm, a SnO.sub.2 layer 65 with a thickness of 0 nm to 15 nm and a ZnO:Al layer 66 with a thickness of 5 nm to 29 nm. In the case of a layer with a minimum thickness specification of 0 nm, this means here and below that this layer could be optionally omitted.

[0056] On the uppermost layer 66 of the intermediate layer 6 a further silver layer 7 is arranged, which has a thickness between 10 nm and 17 nm, for example. The first silver layer 3 and the second silver layer 7 of the layer system serve in particular to reflect infrared radiation and are therefore essential optical functional layers of the solar glass.

[0057] The second silver layer 7 is followed by a cover layer 8 in the direction of growth. The cover layer 8 contains a NiCrO.sub.x layer 81, which is applied directly to the other silver layer 7 and preferably has a thickness between 0.5 nm and 4 nm. This suboxidic NiCrO.sub.x layer 81 serves in particular to protect the second silver layer 7 from oxidation.

[0058] The cover layer 8 is followed in the direction of growth by a ZnO:Al layer 82 with a thickness between 12 nm and 31 nm and a SnMayer 83 with a thickness between 0 nm and 16 nm.

[0059] The last layer of layer system 10 in the direction of growth is advantageously a SiO.sub.xN.sub.y layer 84, which preferably has a thickness between 6 nm and 10 nm. This last layer 84 of the layer system in the growth direction protects the layer system in particular against oxidation.

[0060] FIGS. 2A to 2C schematically illustrate possible configurations of the gradient of the absorber layer in the layer system of the solar glass 100. FIG. 2A shows a top view of an example of the design of solar glass 100. The shading shows the gradient of the thickness of the absorber layer 4 in the layer system 10 of the solar glass. Here, the light area in the middle has a smaller thickness of the absorber layer than the darker areas at the upper and lower edge of the solar glass 100. This ensures that the g-value in the layer system varies.

[0061] The solar glass 100 can, for example, be a window pane that is intended for use as solar control glazing. The exemplary embodiment of solar glass 100 can be a room-high window pane, for example. The direction z shown is the vertical direction of the solar glass 100, which may correspond to the height above the floor, for example. The absorber layer has a high transparency in the central area of the window pane, which corresponds in particular to the visible area. In the upper and lower area of the solar glass 100, on the other hand, the absorber layer has a greater thickness, so that the g-value and light transmission in these areas are lower. In this way, it can be achieved in particular that the input of solar energy is not too great in the middle area despite the high transparency and the associated low g-value. For example, the lower transparency in the floor area can be used to achieve visual protection.

[0062] A possible course of the thickness d.sub.A of the absorber layer in the direction z is shown schematically in FIG. 2B. The absorber layer has a greater thickness than in the middle of the solar glass for small and large values for z, i.e., for example in the lower and upper areas of the solar glass 100.

[0063] As an alternative to the spatial variation of the thickness of the absorber layer, a spatial gradient of the g-value and the light transmission can be achieved by a spatial variation of the material composition of the absorber layer. For example, the absorber layer may contain NiCr, where the concentration of nickel c.sub.Ni varies in the z direction. As shown in FIG. 2C, the concentration of nickel is greater than in the central region at small values and large values of the vertical coordinate z, i.e., for example in the floor and ceiling region of the solar glass 100. In this way, the g-value and the light transmission in the central area of the solar glass are greater than in the lower or upper area.

[0064] The variation of the thickness of the absorber layer according to FIG. 2B and the variation of the concentration of nickel according to FIG. 2C are thus two alternative ways of realizing a gradient of the g-value and light transmission in the solar glass 100.

[0065] A gradient of the thickness of the absorber layer as in the example of FIG. 2B can be created in the production of the layer system of the solar glass 100 by one of the technical measures described above, in particular by varying the sputtering power when sputtering the absorber layer, by varying the transport speed of the glass, by one or more apertures between the cathode provided for sputtering the absorber layer and the glass substrate, by an inhomogeneous magnetic field in the sputtering system or by an inhomogeneous process gas in the sputtering system.

[0066] A gradient of the nickel concentration as in the example of FIG. 2C can be generated as described above by an inhomogeneous cathode in which, for example, the nickel content varies in a direction perpendicular to a transport direction of the glass substrate in the sputtering system.

[0067] The gradients of the thickness of the absorber layer or the nickel concentration shown in FIGS. 2A to 2C, which have a minimum in the middle of the glass substrate and a maximum at the edges, are purely exemplary. Of course, depending on the application of the solar glass, any other gradients of thickness or concentration of e.g., nickel in the absorber layer can be produced. In particular, it is possible to create a gradient in two directions. This can be achieved, for example, by combining a method for generating a gradient parallel to the transport direction of the glass substrate in the sputtering system with a method for generating a gradient perpendicular to the transport direction of the glass substrate. For example, the transport speed during sputtering of the absorber layer can be varied to produce a spatially varying thickness parallel to the transport direction, and at the same time an aperture between the cathode and the glass substrate can be used to produce a thickness gradient in the direction perpendicular to the transport direction.

[0068] FIG. 3A shows a top view of the solar glass 100 at an intermediate step of the process for producing the solar glass before the application of the absorber layer. In this exemplary embodiment of the method, a mask layer 9 is applied to the layer below, in particular to the first silver layer of the layer system, before the absorber layer is applied. In the exemplary embodiment, mask layer 9 is designed as a dot mask in which the mask dots have a spatially varying size. As can be seen in FIG. 3A, the size of the mask dots varies, for example, in the vertical z-direction in such a way that the mask dots in the center of the solar glass 100 are larger than at the lower and upper edges of the solar glass. With an alternative design, instead of the size of the mask dots, their density could be varied spatially. The size of the mask dots of mask layer 9 is preferably not more than 3 mm, especially in the range of 0.5 mm to 3 mm. Such a small size of the mask dots has the advantage that the structuring of the absorber layer is essentially not visible in architectural glass.

[0069] The mask dots of mask layer 9, for example, can be formed from a water-soluble mask material, preferably applied by screen printing. The absorber layer is subsequently applied to mask layer 9 by sputtering. The areas of the absorber layer covered by the mass dots are then lifted off by a so-called lift-off process, so that the absorber layer remains only in those areas that were not previously covered by the mask dots.

[0070] In this way, a spatially varying surface coverage density A of the absorber layer is generated, as shown in FIG. 3B as an example. In particular, in this example, the surface coverage density A can vary in the vertical direction Z in such a way that it is maximum in the lower and upper area of the solar glass 100 and minimum in the center of the solar glass 100. The effect on the g-value and light transmission in this case is comparable to the exemplary embodiments in FIGS. 2A to 2C, i.e., with such a solar glass a high g-value combined with a high light transmission is achieved in the center and a low g-value combined with a low light transmission in the lower and upper area.

[0071] By a different choice of the mask layer, of course, other gradients of the surface coverage density as well as the g-value and light transmission can be produced.

[0072] The invention is not limited by the description based on the exemplary embodiments. Rather, the invention comprises each new feature as well as each combination of features, which in particular includes each combination of features in the claims, even if this feature or combination itself is not explicitly stated in the claims or exemplary embodiments