PHOTOVOLTAIC CONCRETE, ITS METHOD OF MANUFACTURE AND CONSTRUCTION ELEMENT INCLUDING SUCH A CONCRETE

Abstract

A concrete having a smooth surface, which is wholly or partly coated with a polymer film obtained by polymerisation under the action of radiation, where the film is itself wholly or partly coated with a thin photovoltaic film.

Claims

1. A method for manufacture of a photovoltaic concrete, comprising: obtaining a concrete; applying a composition containing monomers and/or reactive unpolymerised prepolymers over all or part of a surface of the concrete; polymerising this composition under the action of radiation, so as to obtain a polymer film wholly or partly covering the surface of the concrete; applying by cathodic sputtering, by chemical deposition in the vapour phase, by ionic deposition, by plasma deposition, by electron bombardment, by laser ablation, by epitaxy by molecular jets, or by thermo-evaporation, at least one thin photovoltaic layer directly on to the polymer film.

2. The method according to claim 1, wherein a temperature of the composition, at the time when it said composition is applied on to the concrete, is below 35 C.

3. The method according to claim 1, further comprising mould-removal and/or heat treatment of the concrete.

4. The method according to claim 1, not including any step of bonding of the thin photovoltaic film on to the polymer film.

5. The method according to claim 1, for which the concrete has a surface, before coating by the polymer film, with a roughness Ra of between 0.5 m and 10 m.

6. The method according to claim 1, for which the concrete has a surface, after coating by the polymer film, with a roughness Ra of between 0.1 m and 5 m.

7. A photovoltaic concrete able to be obtained by the method of claim 1.

8. The photovoltaic concrete according to claim 7 wherein said concrete is an ultra-high-performance concrete.

9. The photovoltaic concrete according to claim 7, wherein the thin photovoltaic layer of which generates electricity through the photovoltaic effect.

10. A method comprising utilizing a polymer film obtained by polymerisation under the action of radiation and of a thin photovoltaic layer, to generate electricity on a concrete surface.

11. An element for the construction field including a photovoltaic concrete according to claim 7.

12. A method for manufacture of an element for the construction field including a photovoltaic concrete, comprising manufacturing the photovoltaic concrete according to claim 1.

13. The method according to claim 2, wherein the temperature of the composition, at the time when said composition is applied on to the concrete, is below 30 C.

14. The method according to claim 5, wherein the roughness Ra is between 0.5 m and 7 m.

15. The method according to claim 14, wherein the roughness Ra is between 0.5 m and 5 m.

16. The method according to claim 14, wherein the roughness Ra is between 0.5 m and 3 m.

17. The method according to claim 6, wherein the roughness Ra is between 0.2 m and 3 m.

18. The method according to claim 17, wherein the roughness Ra is between 0.3 m and 1 m.

19. The method according to claim 18, wherein the roughness Ra is between 0.4 m and 0.6 m.

Description

EXAMPLES

[0132] The following examples show how the surface of the coated concrete according to the invention resists the conditions of deposition of thin photovoltaic layers whilst enabling surface properties appropriate for photovoltaic applications to be obtained.

[0133] Ultra-high-performance concrete formulation (1):

[0134] Ultra-high-performance concrete formulation (1) used to conduct the tests is described in the following table (1):

TABLE-US-00001 TABLE (1) Proportion (% by mass relative to the mass of Components the composition) Portland cement 31.0 DURCAL 1 limestone filler 9.3 MST silica fumes 6.8 BE01 sand 44.4 Waste water 7.1 Ductal F2 additive 1.4

[0135] The components used are available from the following suppliers:

(1) CEM I 52.5 PMES white Portland cement: Lafarge-France Le Tell
(2) DURCAL 1 limestone filler (average particle size 2.44 m): OMYA
(3) MST silica fumes: SEPR (Socit Europenne des Produits Rfractaires)
(4) BE01 sand (D50 to 307 m and D10 to 253 m): Sibelco France (SIFRACO BEDOIN quarry)
(5) Ductal F2 additive: Chryso

[0136] The Portland cement is of the CEM I 52.5 PMES type according to standard EN 197-1 of February 2001. The Ductal F2 additive is a superplasticiser including a polyoxyalkylene polycarboxylate in the aqueous phase with 30% dry extract. The silica fumes have a median particle size of approximately 1 micron. The water/cement ratio is 0.26. This is a concrete with a compression resistance after 28 days higher than 100 MPa.

[0137] The ultra-high-performance concrete according to formulation (1) was produced by means of a RAYNERI type mixing machine. The entire operation was conducted at 20 C. The preparation method includes the following steps: [0138] At T=0 seconds: put the cement, the limestone filler, the silica fumes and the sand in the mixing machine drum and blend for 7 minutes (15 rpm); [0139] At T=7 minutes: add the water and half the mass of additive, and blend for 1 minute (15 rpm); [0140] At T=8 minutes: add the remaining additive, and blend for 1 minute (15 rpm); [0141] At T=9 minutes: blend for 8 minutes (50 rpm); [0142] At T=17 minutes: blend for 1 minute (15 rpm). [0143] Starting from T=18 minutes: pour the concrete flat in the moulds intended for this purpose.

[0144] Plates (dimensions 15010010 mm) were produced by moulding of the concrete according to formulation (1) in a polyvinyl chloride (PVC) mould. Each plate was removed from its mould 18 hours after contact between the cement and the water. Each plate removed from the mould was stored at 25 C. for 14 days.

[0145] After being stored for 14 days a surface treatment of the plates was applied. Coating (1) according to the invention was applied on a face of the first plate. Comparison coatings (2) and (3) were applied on a face of the second and third plates. No coating was applied to the fourth plate.

Method of deposition of a coating (1) according to the invention of a composition including reactive monomers and/or prepolymers:

[0146] The following chemical compounds were used to produce coating (1):

TABLE-US-00002 TABLE (2) Composition of coating (1) Commercial name Chemical name % by mass Photomer 6010* Urethane acrylate oligomer 70 Photomer 4071 F* Methyl pentanediol diacrylate 10 (MPDDA) Photomer 3016 F* Epoxy acrylate oligomer 15 Irgacure 184* 1-hydroxycyclohexyl-phenyl ketone 5 *Photomers are sold by the company IGM Resins. Irgacure is sold by the company Ciba.

[0147] The compounds of coating (1) were loaded in a mixer, and then stirred at ambient temperature until a uniform blend was obtained. The blend was stable, and it was able to be kept for several months at ambient temperature away from direct sunlight. This blend was applied on to ultra-high-performance concrete (1), using an applicator roller, and then set to polymerise under the action of UV radiation. UV radiation enables the photoinitiator to be broken down, which leads to polymerisation of the acrylic groups.

[0148] The polymerisation was accomplished at a speed of passage under the UV lamp of between 5 metres/minute and 30 metres/minute; the dose of energy received was sufficient to obtain the most possible complete polymerisation and to prevent any sticky effect at the surface of the polymer film.

[0149] Method of deposition of a comparison coating (2):

[0150] The method was accomplished at 20 C. and included, after a wait of 14 days after the concrete for treatment was removed from the mould, deposition, on the face of the concrete element to be treated, of an aqueous emulsion (consisting of butyl methacrylate, aliphatic esters, carboxylic acids and ether glycol), in actuality the product PROTECTGUARD Effet Mouill Brillant [Gloss Wet Effect] sold by the company Guard Industrie. The coating was deposited by means of a roller which had been moistened by this liquid. Two layers were deposited (2 hours between each application).

[0151] Method of deposition of a comparison coating (3):

[0152] The method was accomplished at 20 C. and includes, after a wait of 14 days after the concrete for treatment was removed from the mould, deposition, on the face of the concrete element to be treated, of a first layer of an acrylic polymer diluted in an aqueous solution (in actuality the product Solarcir Primer Protec sold by the company Grace-Pieri). The emulsion was sprayed at a rate of 40 g/m.sup.2. This method then included a wait of 24 hours after the first layer dried, followed by the deposition of a second polyurethane-based layer (in actuality the product Solarcir Protec Mat sold by Grace-Pieri). This second layer was sprayed at a rate of 80 g/m.sup.2.

[0153] The plates were then used to conduct the various tests and measurements described below.

[0154] Durability of the visual surface appearance:

[0155] After the surface treatment, plates were stored at 200 C. for 2 hours in a partial vacuum (pressure<0.1 atmosphere) to verify the deformation resistance of the surfaces in a constrictive environment, close to the one required for the deposition of thin photovoltaic layers. A visual inspection was then made to examine the surfaces of the plates and to detect possible defects. The results of these visual inspections are presented in the following table (3):

TABLE-US-00003 TABLE (3) Visual inspection after 2 hours at 200 C. plate with coating plate with plate with in a partial (1) according to comparison comparison vacuum the invention coating (2) coating (3) Formation of No formation of Formation of bubbles bubbles in the bubbles in the coating coating Formation dark No Yes Yes and light spots

[0156] The concrete covered with coating (1) according to the invention has neither spots nor bubbles, whereas the concretes coated with comparison coatings (2) or (3) have at least one of these defects.

[0157] Variation of roughness and deformation resistance:

[0158] Average roughness measurements (Ra parameter) of the plates' treated faces (and of the uncoated plate) were made at 200 C. for 2 hours in a partial vacuum (pressure<0.1 atmosphere) to verify deformation resistances of the surface in a constrictive environment, close to the one required for deposition of thin photovoltaic layers. The results of these roughness measurements are presented in the following table (4):

TABLE-US-00004 TABLE (4) Measurement by plate with profilometry of coating (1) plate with plate with plate average roughness according to the comparison comparison without (Ra) invention coating (2) coating (3) coating Before being stored 0.5 m 1.0 m 2.0 m 1.0 m for 2 hours at (+/0.1) (+/0.5 m) (+/0.5 m) (+/0.5 m) 200 C. in a partial vacuum After being stored 0.5 m 1.5 m >5 m 1.5 m for 2 hours at (+/0.1) (+/0.5 m) (+/0.5 m) 200 C. in a partial vacuum

[0159] The concrete covered with coating (1) according to the invention has no variation of average roughness (Ra), whereas the concretes covered with comparison coatings (2) or (3) have a higher surface deformation; the concrete covered with coating (1) is therefore more favourable for the deposition of a thin photovoltaic layer. The concrete without a coating has a higher average roughness than that of the concrete covered with coating (1), which is less favourable for the deposition of a thin photovoltaic layer.

[0160] Hardness and scratch-resistance:

[0161] After the surface treatment, plates were subjected to a scratch-resistance test (according to standard ISO 2409:2007 (Paints and varnishescheckering test) which consisted in making a checker pattern by making parallel and perpendicular incisions in the coating.

[0162] After the incisions were made a surface photograph of each plate was then taken. The results of a visual comparison of the two photographs are shown in the following table (5):

TABLE-US-00005 TABLE (5) Visual Plate with coating (1) Plate with comparison inspection according to the invention coating (3) Appearance Slight visible degradation Degradation of the after the of the coating; the fine coating; the large incisions incisions incisions do not penetrate penetrate as far as the as far as the concrete concrete

[0163] The concrete covered with coating (1) has surface properties enabling scratching to be resisted; no incision cut through the entire thickness of the coating.

[0164] Open Surface Porosity and Permeability to Liquids

[0165] FIG. 1 represents device 10 used to measure the permeability of plate 12; this measurement of water permeability can characterise the residual porosity of the surface of the concrete (with/without coatings). Plate 12 is positioned on spacers 14 approximately 5 mm from a horizontal bracket 16. The treated face of plate 12 is upper face 18. A tapered funnel 20 with a vertical axis is positioned on upper face 18, with the large-diameter end of funnel 20 in contact with upper face 18. The larger diameter of the funnel measures 75 mm. A sealing device 22 covers the area of contact between funnel 20 and face 18. The small-diameter end of funnel 20 is extended by a graduated pipette 24. A sealing device 26 covers the area of contact between funnel 20 and pipette 24.

[0166] The test to measure permeability was made for each plate after the surface treatment, using the test device of FIG. 1 at a temperature of 20 C., with a relative humidity of 65%. Water was poured into pipette 24 so as to fill funnel 20 and pipette 24 up to a height of 250 mm relative to face 18. The change in the quantity of water penetrating into the plate was measured on pipette 24. The results are shown in the following table (6):

TABLE-US-00006 TABLE (6) Quantity of water penetrating the: plate with coating (1) plate with plate with plate Measuring according to the comparison comparison without time invention coating (2) coating (3) coating (hours) (mL/m.sup.2) (mL/m.sup.2) (mL/m.sup.2) (mL/cm.sup.2) 0 0 0 0 0 96 0.05 0.40 0.60 0.30 120 0.05 0.40 0.60 0.30 144 0.05 0.40 1.10 0.30 168 0.05 0.70 1.10 0.30 192 0.05 0.70 1.10 0.30 216 0.06 0.90 1.70 0.60

[0167] The concrete covered with coating (1) according to the invention is therefore more impermeable than the concrete covered with comparison coating (2) or (3), and also more impermeable than the concrete not covered with a coating. The high impermeability of plate (1) coated according to the invention reveals a very low open surface porosity, which is very favourable for the deposition of thin photovoltaic layers enabling the photovoltaic concrete according to the invention to be formed.

[0168] To be able to support a uniform deposition of thin photovoltaic layers, in particular during the deposition phases accomplished in a partial vacuum (10.sup.4 Torr), and with a concrete temperature raised to approximately 200 C. (or higher), the concrete should advantageously be: [0169] as smooth as possible, and have no surface deformation (tables 3 and 4), [0170] be as scratch-resistant as possible (table 5), [0171] have the lowest possible open surface porosity (table 6).

[0172] On examining the results, the ultra-high-performance concrete of formulation (1) covered with coating (1) is the one which has the best surface characteristics to receive in situ deposition of thin photovoltaic layers.

[0173] After having selected coating (1) to cover a surface of the ultra-high-performance concrete of formulation (1), tests involving deposition of a conducting layer to form the rear contact of the thin photovoltaic layers were made, with various materials and using various methods.

[0174] 1) 1st test of deposition of Molybdenum by cathodic sputtering (deposit n 1):

[0175] The deposition was effected by cathodic sputtering on two concrete substrates of formulation (1) covered with coating (1), at a pressure of 2 mTorr and with an argon flow of 20 sccm. The argon plasma was created using radio-frequencies (13.56 MHz) at a power level of 300 W.

[0176] When these parameters had stabilised the molybdenum target was exposed to the argon ions, which led to a deposition speed of 22.2 nm/min. Both substrates were placed on a rotating sample-holder which rotates at approximately 5 rpm, and left for 1330 under the molybdenum flow to obtain a layer 300 nm thick.

[0177] In terms of roughness the Ra after deposition is 0.03 m; the flatness of deposition n 1 is indeed preserved, according to the observations using the profilometer and scanning electron microscope. Both these new substrates are therefore able to support a future deposition of CZTS layers with a view to obtaining the photovoltaic concrete according to the invention.

[0178] 2) 1st test of deposition of gold by vacuum evaporation (deposit n 2):

[0179] The concrete substrate of formulation (1) covered with coating (1) was firstly treated for five minutes by an O.sub.2 plasma generated at approximately 0.1 mbar by radio-frequencies at a power level of 100 W, with an O.sub.2 flow of 5 sccm.

[0180] When this treatment had been accomplished a secondary vacuum was applied in the chamber (10 to 2 mbar) and the gold evaporated. The substrate was then placed under the gold source when the sublimation commenced under the effect of the heating caused by heating a tungsten filament.

[0181] A first deposition of gold by evaporation was therefore made. Problems of calibration of the quartz balance and of stability of the sublimation led to a gold deposition of 730 nm, a needlessly high thickness, and one which was therefore not uniform.

[0182] Despite this, the measurements by profilometry showed that deposit n 2 was as smooth as the molybdenum deposit (Ra=0.034 m), and therefore potentially able to support a future deposition of CZTS layers with a view to obtaining the photovoltaic concrete according to the invention.

[0183] 3) 2nd and 3rd tests of deposition of gold by vacuum evaporation (deposits n 3 and n 4)

[0184] After calibrating the device, depositions by evaporation of finer gold layers, respectively 55 and 150 nm thick, were made according to a method identical to the method described above for deposit n 2.

[0185] Measurement of Resistivity

[0186] By applying a voltage and by measuring the current, it was possible to measure the resistance of the metal deposits, and by this means to determine their resistivities very approximately, in particular by using the Van der Pauw method.

[0187] All these resistivity measurements are shown in the following table:

TABLE-US-00007 thick- resis- Deposition ness Roughness tance resistivity Deposit Metal method (nm) (Ra, m) () ( .Math. cm) no1 Mo Cathodic 300 0.03 4.17 5.7E04 sputtering no2 Au Deposition 730 0.034 1.67E+05 5.5E+01 by evaporation no3 Au Deposition 55 0.07 4 1.0E04 by evaporation no4 Au Deposition 150 0.09 0.9 6.1E05 by evaporation

[0188] These resistivity measurements enabled it to be determined that deposits n 1 and n 3 were conducting, but that deposit n 2 was not.

[0189] The matt and dark appearance of the first deposit by evaporation of gold (deposit n 2) suggests that polymer coating (1) was degraded during the deposition, and that a part of this insulating coating became mixed with the sputtered gold, by this means making the gold deposit more resistive.

[0190] Deposits n 1 (molybdenum) and n 3 and 4 (gold), which are less thick than deposit n 2, are better controlled, and have a correct resistivity compatible with applications of thin photovoltaic layers described in the state of the art.

[0191] Adherence Test

[0192] The adherence tests made according to standard ASTM D 3359 showed that all the layers of molybdenum and gold had correctly adhered with the concrete substrate of formulation (1) covered with polymer coating (1).

[0193] Tests of deposition of CZTS layers were then made on some of the conducting layers described above.

[0194] 4) Deposition of CZTS layers on concrete substrates of formulation (1) covered with polymer coating (1) previously covered with a layer of molybdenum (deposit n 1) or a layer of gold (deposit n 3)

[0195] The layers of CZTS were deposited in two stages:

[0196] 4.1. Firstly co-evaporation of ZnS, Cu2S and SnS was undertaken. These three metal compounds were heated by conduction in vacuum crucibles, the pressure during the deposition was of the order of 10.sup.6 mbar, this temperature potentially rising to 510.sup.5 mbar or higher during the deposition but not exceeding 110.sup.5 mbar. The deposition speeds (in nm/s) and temperatures of the metals ( C.) are given in the table below:

TABLE-US-00008 SnS Cu2S ZnS T ( C.) 570 1210 900 nm/s 0.49 0.23 0.32

[0197] The aim was to obtain Cu2ZnSnS.sub.4; the theoretical speed ratios were that: [0198] the deposition of SnS occurred 1.22 times faster than ZnS, and that [0199] the deposition of Cu2S occurred 1.2 times faster than ZnS.

[0200] 4.2. Once the deposit had been produced a layer of Cu2-xZnSn1+yS3+z was obtained. Sulphurisation was then effected. To accomplish this, samples were placed in a kiln with crucibles containing solid sulphur. The atmosphere of the kiln was a dinitrogen flow, so as to stabilise the pressure at 1 mTorr. The samples were heated for 1 hour at 60 C., and then for 3 minutes at 120 C., and finally for a quarter of an hour at 500 C.

[0201] Characteristics after Deposition:

[0202] Measurements of chemical composition by X-ray electronic spectroscopy (XPS) enabled it to be confirmed that the various layers had indeed been deposited on the concrete substrates of formulation (1) covered with polymer coating (1) previously covered with a molybdenum layer (deposit n 1) or a gold layer (deposit n 3).

[0203] The measurements by profilometry give a final roughness (Ra) after deposition of the CZTS of 0.35 m in both cases.

[0204] The accomplished deposition of thin CZTS layers could be used as a basis for the production of a complete photovoltaic cell.