Transparent photovoltaic laminated glazing with thermal comfort and neutral color during transmission

Abstract

The invention relates to a laminated glazing (1) for a motor vehicle roof, comprising an outer glass sheet (2), an inner glass sheet (3), a lamination adhesive intermediate layer (4), a perovskite photovoltaic cell (5), a colored layer (6) and a solar control stack (7), the laminated glazing (1) comprising, starting from the inner glass sheet (3): the colored layer (6), the perovskite photovoltaic cell (5), the lamination adhesive intermediate layer (4), the solar control stack (7) and the outer glass sheet (2), and to a method for manufacturing this laminated glazing (1).

Description

[0001] DESCRIPTION TITLE: TRANSPARENT PHOTOVOLTAIC LAMINATED GLAZING WITH THERMAL COMFORT AND NEUTRAL COLOUR TRANSMISSION

[0002] technical field

[0003] The invention relates to laminated glazing of the type used for example as an automobile roof, in particular comprising photovoltaic cells (or modules) capable of converting part of the received solar spectrum into producing electric current.

[0004] Previous technique

[0005] One approach could be to space out photovoltaic cells of varying opacity to create transparent areas between them. However, this would result in optical inhomogeneities degrading the aesthetic appearance from both the inside and outside, and an overall darkening that would compromise visual comfort.

[0006] Alternatively, one could consider replacing conventional opaque photovoltaic cells or modules, such as silicon-based ones, with perovskite photovoltaic cells, as the layers and films of this material can be semi-transparent. Indeed, by varying the thickness of a perovskite film, satisfactory compromises can be achieved for the use of laminated photovoltaic glazing as a car roof or similar application. This compromise is summarized by the values ​​of two parameters: Visible Light Transmission (VLT) of 20% and Power Conversion Efficiency (PCE) of 10%, or, for a slightly greater film thickness: VLT of 10% and PCE of 15%, for example.

[0007] Within the framework of the invention, all values ​​of light transmission, visible light absorption, (near) infrared radiation, ultraviolet radiation, total solar energy transmission factor, solar factor g, are defined and determined in accordance with standard EN 410:201 1.

[0008] Based on the observation that a perovskite photovoltaic cell or module primarily converts electromagnetic radiation of visible wavelength to produce electrical current, particularly with wavelengths between 300 and 740 nm, or up to 600 nm, the inventor was able to establish that an infrared-reflective (IRR) solar stack placed between the sun and a perovskite photovoltaic layer had virtually no effect on the latter's conversion efficiency. The invention aimed to provide a semi-transparent laminated photovoltaic glazing equipped, upstream of the photovoltaic layer relative to the sun, with an solar stack.It was important that the photovoltaic layer have a sufficiently high conversion efficiency, that the solar blocking layer provide adequate thermal comfort, and that it be positioned on the inner face of the laminated glass sheet intended to be in contact with the outside atmosphere. By numbering the faces of all the glass sheets constituting the laminate, starting with 1 (face F1) for the glass face in contact with the outside atmosphere, it was advantageous to be able to position the solar blocking layer on face 2 (face F2) of the laminate, particularly considering the ease of industrial manufacturing.

[0009] Description of the invention

[0010] This objective has been achieved by the invention which, consequently, relates to a laminated glazing for a motor vehicle roof comprising an outer glass sheet, an inner glass sheet, an intermediate adhesive lamination layer, a perovskite-based photovoltaic cell, a coloured layer and a solar control stack, the laminated glazing comprising, starting from the inner glass sheet, the coloured layer, the perovskite photovoltaic cell, the intermediate adhesive lamination layer, the solar control stack and the outer glass sheet.

[0011] The intermediate layer of lamination is opportunely clear (untinted) so as to allow access to the photovoltaic layer by a maximum proportion of visible light from solar radiation.

[0012] The perovskite-based photovoltaic cell is semi-transparent in the visible spectrum, where, at moderate thicknesses, it can achieve a maximum light transmission of, for example, 20% in the visible range. It thus also provides a degree of transparency to laminated glass, making it ideally suited for use in automotive roofs. The perovskite photovoltaic cell comprises the perovskite layer, transparent electrodes, buffer layers, etc., in a known manner.

[0013] Due to the selective absorption of the shortest visible wavelengths by the perovskite cell to produce electric current, the photovoltaic cell's transmission in the visible range is strongly colored orange. With this invention, the colored layer absorbs visible wavelengths to neutralize the transmitted color of the entire photovoltaic cell and the colored layer. The colored layer is chosen to decrease the value of a* to correct / attenuate the undesirable brown / red color of the perovskite photovoltaic cell, and / or the value of b* to attenuate the undesirable yellow color of the perovskite photovoltaic cell. Preferably, the value of both parameters is decreased simultaneously by the colored layer, which could be blue, for example.

[0014] Preferably, laminated glazing includes a low-emissivity coating deposited on the inner glass sheet, the inner glass sheet being positioned between the low-emissivity coating and the coloured layer.

[0015] Preferably, the solar control stack is deposited by the magnetron process and comprises at least two metallic functional layers, in particular two or three metallic layers, especially silver. The magnetron process is understood to be a magnetically assisted (magnetron) sputtering, for example under a certain vacuum or pressure reduced relative to atmospheric pressure.

[0016] The laminated glass is advantageously curved in accordance with current aesthetic criteria, for example, for an automobile roof. The structure of the laminated glass of the invention can easily be industrially produced with a curved shape.

[0017] Preferably, the intermediate adhesive layer of the laminate and the colored layer each comprise a transparent adhesive material (also called OCA for "Optical Clear Adhesive") in liquid form before the assembly of all the constituent elements of the laminated glazing and suitable for crosslinking, selected from acrylic, polyvinyl acetate (PVA), polyurethane (PU), silicone, and epoxy, alone or in a mixture of several of these, or a polymer selected from polyvinyl butyral (PVB), polyurethane (PU), ethylene-vinyl acetate copolymer (EVA), casting resin, ionomer resin, or equivalent, alone or in a copolymer or mixture of several of these, and each have a thickness of between 50 and 1600 µm, preferably not exceeding 1 mm, or even 0.5 mm. Said polymer, when selected from PVB, PU, ​​or EVA, may or may not contain a plasticizer.Preferably, the colored layer comprises, or is essentially composed of, a transparent adhesive material (OCA). Then, the intermediate adhesive layer of the laminate preferably comprises essentially a polymer selected from polyvinyl butyral (PVB), polyurethane (PU), or ethylene-vinyl acetate copolymer (EVA).

[0018] Preferably, the outer glass sheet is a clear glass sheet, i.e. untinted, and particularly preferably extra clear, with a light transmission of at least 88%, or even 90%.

[0019] Depending on the light transmission of the other components of the laminated glass, the inner glass pane may preferably be tinted; its light transmission is then at most 50%, and in increasing order of preference, 40% and 30%. However, the inner glass pane is not necessarily tinted, particularly when a clear glass inner pane allows for a sufficiently low visible light transmission (VLT) of the laminated glass, which may be required in certain applications such as for an automotive roof, such as at most 10%.

[0020] Preferably, the outer glass sheet and the inner glass sheet are made of mineral glass such as soda-lime, aluminosilicate, borosilicate, possibly thermally tempered or chemically strengthened, and each have a thickness between 0.7 and 2.5 mm.

[0021] Another object of the invention consists of a method for manufacturing laminated glazing described above, characterized in that it comprises the following steps: stacking, in this order, the inner glass sheet optionally supporting a low-emissivity coating, the coloured layer on the side of the inner glass sheet opposite, where applicable, the low-emissivity coating, the photovoltaic cell based on a perovskite layer, the intermediate adhesive lamination layer, and the outer glass sheet supporting the solar control stack oriented towards the intermediate adhesive lamination layer, the coloured layer and the intermediate adhesive lamination layer being made, each independently of the other, of a liquid transparent adhesive material (OCA) or a solid polymer sheet;crosslink the liquid OCA and / or proceed with the lamination operation by heating under pressure the solid polymer sheet(s), depending on the composition of the colored layer and the intermediate adhesive lamination layer, to obtain the laminated glazing.

[0022] This process does not exclude the layering of additional, undescribed elements.

[0023] Liquid OCA is suitable for crosslinking and hardening by polymerization methods such as ultraviolet radiation. OCA is, for example, an acrylic resin. A solid polymer sheet used in the context of the invention is a thermoplastic sheet, particularly of PVB, PU, ​​or EVA. The lamination operation by heating under pressure of a solid polymer sheet preferably includes placing the entire stack in a vacuum bag (instead of calendering the stack) to expel the air, and then autoclaving it under mild conditions (maximum pressure of 15 bar and maximum temperature of 140 °C, typically 12 bar and 120 °C).

[0024] When at least one of the colored layer and the intermediate adhesive layer of the lamination is made of a liquid transparent adhesive material (OCA), its implementation consists of maintaining the inner glass sheet spaced from the perovskite photovoltaic cell, and / or the latter spaced from the solar control stack supported by the outer glass sheet, to provide a cavity to be filled with the liquid OCA, the spacing and sealing being achieved by a peripheral sealing joint including spacers, to provide one or more openings in the sealing joint in order to introduce the liquid OCA by injection through them until it occupies the entire cavity between the inner glass sheet and the perovskite photovoltaic cell, and / or between the perovskite photovoltaic cell and the solar control stack,and finally to crosslink the OCA to form the colored layer and / or the adhesive intermediate layer of the laminate.

[0025] In an advantageous embodiment of the process of the invention, the adhesive intermediate layer of lamination is formed from a solid polymer sheet and the colored layer from liquid OCA, and the manufacturing process comprises the following steps:

[0026] - stack in this order the perovskite photovoltaic cell, the intermediate adhesive layer of solid polymer sheet lamination, and the outer glass sheet supporting the solar control stack oriented towards the intermediate adhesive layer of lamination;

[0027] - to carry out the lamination operation by heating the adhesive intermediate layer of lamination under pressure, so as to obtain a laminated assembly; and

[0028] - to complete the manufacture of the laminated glazing by assembling the inner glass sheet to the laminated assembly via the colored layer, the cross-linking of the liquid OCA constituting it provides the required adhesion.

[0029]

[0001] In this particular embodiment of the invention, pressure heating lamination is performed on only one side of the perovskite photovoltaic cell (the side facing the adhesive intermediate lamination layer), minimizing the risk of thickness variation. If a temporary support backing glass is used on the other side of the perovskite cell during pressure heating lamination, once the backing glass is removed, the perovskite cell relaxes and any inhomogeneous light transmission spots disappear. Furthermore, the deposition of a liquid material on the other side of the photovoltaic cell will prevent thickness deformation on that side and will provide surface flatness to the interface between this other side of the perovskite cell and the inner glass sheet.Laminated glazing (in the sense of a stack of materials) will present less risk of inhomogeneity in light transmission.

[0030] Brief description of the drawings

[0031] Other features and advantages of the object of this presentation will emerge from the following description of embodiments, given by way of non-limiting examples, with reference to the attached figure.

[0032] [Fig. 1] Figure 1 is a schematic cross-sectional view of a laminated glazing of the invention.

[0033] Detailed description

[0034] Referring to Figure 1, the laminated glazing 1 comprises an inner clear glass sheet 3, 2.1 mm thick, marketed by Saint-Gobain Glass under the registered trademark Planiclear®. Alternatively, a 2.1 mm thick tinted glass sheet marketed by Saint-Gobain Glass under the registered trademark Venus® Grey 10 could be used (10% visible light transmission for a thickness of 4 mm, and 28% for a thickness of 2.1 mm). The inner clear glass sheet 3 supports a low-emissivity coating 8 marketed by Saint-Gobain Glass under the registered trademark ComfortSky®. This coating is on the free face of the inner glass sheet 3 in the laminated glazing 1, the free face intended to face the passenger compartment of the motor vehicle in the installation position of the laminated glazing 1.The low-emissivity coating 8 has the function, in cold weather, of reflecting thermal radiation into the passenger compartment in order to increase the heat for the same heating power, and in hot weather, of absorbing solar heat in order to avoid thermal radiation towards the passengers and promote heat dissipation to the outside.

[0035] The inner glass pane 3 is bonded to a perovskite photovoltaic cell 5 via a 0.200 mm thick colored layer 6 made of a transparent adhesive material (also called OCA for "Optical Clear Adhesive") consisting of an acrylic material. The colored layer 6 contains one or more organic dyes that give it a blue color in transmission, thus giving the laminated glass 1 a neutral color in transmission by neutralizing the orange color in transmission of the perovskite photovoltaic cell 5.

[0036] The perovskite 5-photovoltaic cell produces electric current by absorbing almost all of the electromagnetic radiation with wavelengths between 300 and 500 nm, so that the light transmission at the wavelength of 500 nm is less than 5% through perovskite 5-cells with thicknesses between 60 and 300 nm, and at the wavelength of 700 nm it is 7% for a 5-layer thickness of 300 nm, 24% for a thickness of 240 nm, 34% for a thickness of 180 nm, 39% for a thickness of 140 nm and 55% for a thickness of 60 nm.The absorption of the perovskite photovoltaic cell 5 is sufficiently low in the infrared, particularly for wavelengths of at least 800 nm, so that its production of electric current can be considered unaffected by the interposition of an infrared reflective coating (IRR for "Infra-Red Reflective" in English) between the sun and the perovskite cell 5.

[0037] The perovskite photovoltaic cell 5 is bonded to an outer 2.1 mm thick clear glass sheet 2, marketed by Saint-Gobain Glass under the registered trademark Planiclear®, by a 0.76 mm thick clear polyvinyl butyral (PVB) sheet 4. The outer glass sheet 2 supports a two- or three-layer silver solar control stack 7 on the face of the outer glass sheet 2 that is internal to the structure of the laminated glazing 1, i.e., the face of the outer glass sheet 2 facing the perovskite photovoltaic cell 5.

[0038] The semi-transparency of the perovskite photovoltaic cell 5 provides that of the laminated glass 1. The anti-solar function provided by the solar control stack 7 does not affect the efficiency of the photovoltaic cell 5, even though the infrared-reflecting stack 7 is interposed between the sun and the photovoltaic cell 5, because the latter 5 produces electrical current by almost exclusively converting visible light with a wavelength of at most 700, or even 600 nm. Finally, the transmitted color of the laminated glass is neutral, even though that of the photovoltaic cell 5 is orange, because the colored layer 6 is designed to simultaneously lower, for the entire laminated glass 1, the values ​​of a* and b* relative to those of the photovoltaic cell 5.

[0039] The manufacturing process for laminated glass 1 involves the following steps:

[0040] - stack, in this order, the perovskite photovoltaic cell 5, the PVB sheet 4, and the external glass sheet 2 supporting the solar control stack 7 oriented towards the PVB sheet 4;

[0041] - to carry out the lamination operation by placing the entire stack in a vacuum bag to expel the air, and then placing it in an autoclave under a maximum pressure of 14 bar and a maximum temperature of 130 °C, so as to obtain a laminated assembly of 5; 4; 7; 2; and

[0042] - to complete the manufacture of the laminated glazing 1 by assembling the inner glass sheet 3 to the laminated assembly 5; 4; 7; 2 via the colored layer 6, the crosslinking of the liquid OCA constituting it provides the required adhesion.

[0043] The implementation of the liquid OCA consists of maintaining the inner glass sheet 3 spaced away from the perovskite photovoltaic cell 5, to create a cavity to be filled with the liquid OCA, the spacing and sealing being achieved by a peripheral sealing joint including spacers, to provide one or more openings in the sealing joint in order to introduce by injection through these the liquid OCA until it occupies the entire cavity between the inner glass sheet 3 and the perovskite photovoltaic cell 5, and finally to crosslink the OCA to form the colored layer 6.

[0044] The way in which liquid OCA hardens depends on its nature, with some OCAs crosslinking by polymerization methods such as ultraviolet radiation or other energy input, for example by heating, and others crosslinking at room temperature with the addition of a hardener.

Claims

DEMANDS 1. Laminated glazing (1) for motor vehicle roof comprising an outer glass sheet (2), an inner glass sheet (3), an adhesive laminate intermediate layer (4), a perovskite-based photovoltaic cell (5), a coloured layer (6) and a solar control stack (7), the laminated glazing (1) comprising, starting from the inner glass sheet (3), the coloured layer (6), the perovskite photovoltaic cell (5), the adhesive laminate intermediate layer (4), the solar control stack (7) and the outer glass sheet (2), at least one of the coloured layer (6) and the adhesive laminate intermediate layer (4) is made of a liquid transparent adhesive material (OCA).

2. Laminated glazing (1) according to claim 1, comprising a low emissive coating (8) deposited on the inner glass sheet (3), the inner glass sheet (3) being disposed between the low emissive coating (8) and the coloured layer (6).

3. Laminated glazing (1) according to claim 1 or 2, wherein the solar control stack (7) is deposited by magnetron process and comprises at least two metallic functional layers.

4. Laminated glazing (1) according to any one of claims 1 to 3, the laminated glazing (1) being curved.

5. Laminated glazing (1) according to any one of claims 1 to 4, wherein the intermediate adhesive lamination layer (4) and the coloured layer (6) each comprise a transparent adhesive material (also called OCA for "Optical Clear Adhesive" in English) in liquid form before the assembly of all the constituent elements of the laminated glazing (1) and being suitable for crosslinking, selected from an acrylic material, poly(vinyl acetate) (PVA), polyurethane (PU), silicone and epoxy, alone or in a mixture of several of them, or a polymer selected from polyvinyl butyral (PVB), polyurethane (PU), ethylene-vinyl acetate (EVA) copolymer, casting resin, or ionomer resin, alone or in a copolymer or mixture of several of them, and each have a thickness of between 50 and 1600 pm, preferably not more than 1, or even 0.5 mm.

6. Laminated glazing (1) according to any one of claims 1 to 5, wherein the outer glass sheet (2) is a clear glass sheet.

7. Laminated glazing according to any one of claims 1 to 6, wherein the inner glass sheet (3) is tinted.

8. Laminated glazing (1) according to any one of claims 1 to 7, characterized in that the outer glass sheet (2) and the inner glass sheet (3) are made of mineral glass such as soda-lime, aluminosilicate, borosilicate, optionally thermally tempered or chemically strengthened, and each have a thickness of between 0.7 and 2.5 mm.

9. Method of manufacturing a laminated glazing (1) according to any one of the preceding claims, characterized in that it comprises the following steps: stacking, in this order, the inner glass sheet (3), optionally supporting a low-emissivity coating (8), the coloured layer (6) on the side of the inner glass sheet (3) opposite, where applicable, the low-emissivity coating (8), the photovoltaic cell (5) based on a perovskite layer, the intermediate adhesive lamination layer (4), and the outer glass sheet (2) supporting the solar control stack (7) oriented towards the intermediate adhesive lamination layer (4), the coloured layer (6) and the intermediate adhesive lamination layer (4) being made, each independently of the other, of a liquid transparent adhesive material (OCA) or a solid polymer sheet;crosslink the liquid OCA and / or carry out the lamination operation by heating under pressure the solid polymer sheet(s), according to the constitution of the coloured layer (6) and the intermediate adhesive lamination layer (4), to obtain the laminated glazing (1).

10. A manufacturing method according to the preceding claim, characterized in that the implementation of the liquid OCA consists of maintaining the inner glass sheet (3) spaced apart from the perovskite photovoltaic cell (5), and / or the perovskite photovoltaic cell (5) spaced apart from the solar control stack (7) supported by the outer glass sheet (2), to create a cavity intended to be filled with the liquid OCA, the spacing and sealing being achieved by a peripheral sealing joint comprising spacers, and providing one or more openings in the sealing joint in order to introduce the liquid OCA by injection through them until which occupies the entire cavity between the inner glass sheet (3) and the perovskite photovoltaic cell (5), and / or between the perovskite photovoltaic cell (5) and the solar control stack (7), and finally to crosslink the OCA to form the coloured layer (6) and / or the adhesive intermediate layer of lamination (4).

11. A manufacturing process according to any one of claims 9 or 10, characterized in that the adhesive intermediate layer of lamination (4) is formed from a solid polymer sheet and the colored layer (6) from liquid OCA, and in that the manufacturing process comprises the following steps: - stack in this order the perovskite photovoltaic cell (5), the adhesive laminate intermediate layer (4) in solid polymer sheet, and the external glass sheet (2) supporting the solar control stack (7) oriented towards the adhesive laminate intermediate layer (4); - to carry out the lamination operation by heating under pressure the adhesive intermediate lamination layer (4), so as to obtain a laminated assembly (5; 4; 7; 2); and - to complete the manufacture of the laminated glazing (1) by assembling the inner glass sheet (3) to the laminated assembly (5; 4; 7; 2) via the colored layer (6), the cross-linking of the liquid OCA constituting it provides the required adhesion.

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