Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
  • H01G9/20—Light-sensitive devices
  • H01G9/2068—Panels or arrays of photoelectrochemical cells, e.g. photovoltaic modules based on photoelectrochemical cells
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
  • H01G9/20—Light-sensitive devices
  • H01G9/2004—Light-sensitive devices characterised by the electrolyte, e.g. comprising an organic electrolyte
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
  • H01G9/20—Light-sensitive devices
  • H01G9/2027—Light-sensitive devices comprising an oxide semiconductor electrode
  • H01G9/2031—Light-sensitive devices comprising an oxide semiconductor electrode comprising titanium oxide, e.g. TiO2
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
  • H01G9/20—Light-sensitive devices
  • H01G9/2059—Light-sensitive devices comprising an organic dye as the active light absorbing material, e.g. adsorbed on an electrode or dissolved in solution
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
  • H01G9/00—Electrolytic capacitors, rectifiers, detectors, switching devices, light-sensitive or temperature-sensitive devices; Processes of their manufacture
  • H01G9/20—Light-sensitive devices
  • H01G9/2068—Panels or arrays of photoelectrochemical cells, e.g. photovoltaic modules based on photoelectrochemical cells
  • H01G9/2081—Serial interconnection of cells
• • H—ELECTRICITY
  • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
  • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
  • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
  • H10K85/30—Coordination compounds
  • H10K85/341—Transition metal complexes, e.g. Ru(II)polypyridine complexes
  • H10K85/344—Transition metal complexes, e.g. Ru(II)polypyridine complexes comprising ruthenium
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E10/00—Energy generation through renewable energy sources
  • Y02E10/50—Photovoltaic [PV] energy
  • Y02E10/542—Dye sensitized solar cells
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the present invention concerns vertical electrochemical contacts of photoelectrochemical cells or DSSC (dye-sensitized solar cells) with low visual impact.
• the invention concerns the structure of said vertical electrochemical contacts, integrated into the photovoltaic modules of DSSC cells, aimed primarily at reducing the visual impact of such contacts, but also to an improvement of their operating performance, and a process for their realisation.
• electrochemical contact a contact obtained through an electrolytic solution with a redox shuttle.
• DSSC cells are photovoltaic cells consisting of a multilayer structure delimited by two substrates.
• said substrates are made of transparent materials (preferably glass, but also PET or PEN) and are coated, on the side facing the interior of the multilayer structure, by an electrically conductive coating which is also transparent (usually a transparent conductive oxide, preferably a titanium oxide doped with fluorine or iodine, respectively FTO and ITO).
• the photo-electrode (the anode), positioned on the conductive coating of one of the two substrates, a counter-electrode (the cathode), positioned on the conductive coating of the other substrate, and an electrolyte interposed between said photo- electrode and said counter-electrode.
• the photo-electrode is usually made of a porous titanium oxide, that supports the active material, consisting of a dye capable of transferring electrons following the absorption of a photon.
• the counter-electrode is usually made of platinum, while the electrolytic solution is generally based on iodine ( ) and potassium iodide (Kl).
• Photoelectrochemical cells of this type have been described for example in U.S. Patent No. 4,927,721 ; materials usable in this type of cells have been described for example in U.S. Patent No. 5,350,644.
• the conductive coatings of the structures have high resistances.
• individual cells of this type are not able to generate the voltage levels required in most of the possible applications where a photoelectrochemical cell can be addressed.
• a photoelectrochemical module ie the conductive coatings of each substrate are divided into a plurality of electrically insulated regions, generally shaped as a plurality of stripes side by side, each region of the conductive coating of one of the two substrates being arranged in a position coinciding and only slightly offset in the transverse direction compared to that of a region of the conductive coating of the other substrate, a cell being realised between each pair of coincident regions of the two substrates.
• the side by side photoelectrochemical cells thus obtained, are connected in series with a connection integrated on the same substrate, realised during the making of the module.
• connections in series integrated on the substrate can be made according to different schemes, known as Z connection, W connection and external connection.
• connections of type Z are constituted by a series of vertical contacts, arranged in the space between two adjacent cells, in particular in the space between the long sides of two cells, ie in the space not used for the cell by reason of the offset arrangement of the regions electrically insulated from the conductive coatings of the two substrates, and which connect with each other regions of the electrically insulated conductive coating of the two substrates, according to a configuration which will be explained in greater detail in the following description.
• FIG. 1 there is shown schematically the configuration of a connection of type Z between two cells of a photoelectrochemical module seen in a section transverse to the direction of the stripes defined by the photoelectrochemical cells.
• Figure 1 shows the two substrates, indicated with the reference numeral 10, each of which is coated, on the side facing the other substrate, by a transparent electrically conductive coating 11.
• the conductive coating 11 is divided into electrically insulated regions by means of interruptions 12.
• Each photoelectrochemical cell is made in the area between two overlapping electrically insulated regions of conductive coatings of the two opposing substrates, each cell being comprised of a photo-electrode 13, positioned on the conductive coating 11 of one of the two substrates 10, a counter-electrode 14, positioned on the conductive coating 11 of the other substrate 10, and a liquid electrolyte interposed between said photo-electrode 13 and said counter-electrode 14.
• Each cell is delimited laterally by an encapsulant 16, which serves to retain the liquid electrolyte inside the cell.
• connection in series between the two cells is obtained by means of the vertical electrical contact 17, which connects the offset portion of the electrically insulated region of the conductive coating 11 of one of the two substrates 10 with the coincident staggered portion in the electrically insulated region of the conductive coating 11 of the opposite substrate 10.
• connection path by means of the vertical contact can be schematized by three resistors: a first resistor constituted by the contact resistance between the conductive coating 11 disposed on the first substrate 10 and the vertical electrical contact 17, a second resistor formed by the resistance of the material of the contact vertical electric 17 itself and a third resistor formed by the contact resistance between the electrical contact 17 and the vertical conductive coating 11 disposed on the substrate 10 opposite the first.
• the vertical electrical contact 17 can be realised by means of different technologies:
• connections thus realised, however, have problems of electrical conduction with increasing temperature. This is due to different thermal behavior between the material that constitutes the electric contact and the material of the encapsulant that maintains the liquid electrolyte within the respective cells.
• connections of this type have not optimal conductivity values, besides the problem of the degradation of its performance with increasing temperature.
• connections of this type are extremely visible (usually have a width of 0,5 mm).
• metals and pastes used in the realisation of such electrical contacts are susceptible to corrosion by the electrolyte, namely in particular by the redox couple iodine iodide (the most performant mediator and used widely).
• the solution according to the present invention which aims to solve the problem of performance degradation of the electrical contact as the temperature increases, as well as to increase the transparency, realising a contact not purely electric but more specifically electrochemical.
• electrochemical contact is meant a contact obtained through an electrolytic solution with a redox shuttle.
• electrochemical vertical connections ie consisting of an electrolytic solution with a redox shuttle, perfectly camouflaged within the module, being constituted by a structure very similar to that of the cell itself.
• the vertical electrochemical connections according to the present invention are resistant to thermal and mechanical stresses, highly transparent and chemically inert to the electrolyte.
• the purpose of the present invention is therefore to provide a vertical electrochemical contact of photoelectrochemical cells that allows to overcome the limits of the solutions according to the prior art and to obtain the technical results previously described. Further object of the invention is that said vertical contact can be made with substantially limited costs, both as regards production costs and as regards management costs.
• Another object of the invention is to provide a vertical electrochemical contact of photoelectrochemical cells which is substantially simple, safe and reliable.
• a photovoltaic module comprising two overlapped panels, at least one of which being transparent or semitransparent, and each being constituted by a flat substrate covered, on the side facing towards the other panel, by an electrically conductive coating divided into a plurality of adjacent regions electrically insulated by means of a corresponding number of interruptions, among said panels a plurality of adjacent dye-sensitized solar cells being interposed, one per each electrically insulated region, each of the dye-sensitized solar cells being comprised of a photo- electrode, positioned on the conductive coating of one of the two substrates, a counter-electrode, positioned on the conductive coating of the other substrate, and a liquid electrolyte interposed between said photo-electrode and said counter-electrode, wherein said adjacent dye- sensitized solar cells are connected in series by means of a corresponding plurality of vertical connections, connecting an electrically insulated region of the electrically conductive coating of a substrate, in connection
• said vertical connections comprise two opposed catalytic layers, respectively one catalytic layer per each panel, arranged in contact with the respective conductive coating, a dye support layer, in contact with said catalytic layer of the panel on which the photo-electrodes are located of the dye-sensitized solar cells of the photovoltaic module, said support layer being constituted by a material having the same chemical characteristics (redox potential) and physical characteristics (coefficient of thermal expansion) of the material of the photo-electrode and said dye having chemical characteristics (redox potential) that are the same as those of the dye of said photo-electrodes and a liquid electrolyte, interposed between said dye support layer and the catalytic layer of the opposite panel.
• said dye support layer is made with the same material as the photo-electrode of the cells of the module and moreover said dye of said dye support layer is the same as the photo-electrode of the cells of the module.
• said liquid electrolyte has chemical characteristics (redox potential) that are the sane as those of the cells of the module and preferably is the same as the cells of the module.
• said liquid electrolyte has a higher ionic concentration with respect to that of the cells of the module.
• said photoelectrochemical cells are arranged according to the shape of stripes, and preferably are large between 5 and 8mm.
• FIG. 2 shows schematically the configuration of a connection of type Z between two cells of a photoelectrochemical module, according to a first embodiment of the present invention
• FIG. 3A shows schematically a substrate for the photo-electrode of a photoelectrochemical module according to a second embodiment of the present invention, prior to mating with the corresponding substrate of the counter-electrode,
• Figure 3B shows schematically a substrate for the counter- electrode to the substrate corresponding to the photo-electrode of Figure 3A, prior to mating
• FIG. 4 shows a graph of the efficiency (expressed in terms of efficiency measured at a reference temperature of 25 °C) with changes in temperature (expressed in °C) of a photoelectrochemical module realised according to the present invention
• FIG. 5 shows two side by side photographs, respectively one to the left relative to a module wherein the vertical connections are made according to the prior art and one to the right relative to a module wherein the vertical connections are made according to the teachings of the present invention
• FIG. 6 shows a graph of the efficiency (expressed as the percentage of incident light power converted into useful power) to vary the intensity of illumination (expressed in W/m 2 ) of two different types of photoelectrochemical module realised second the present invention, respectively, with cells arranged into stripes of 5mm and 10mm.
• an objective of the present invention is the realisation of vertical electrochemical connections perfectly camouflaged inside of a photoelectrochemical module, as constituted by a structure very similar to that of the cells of the same photoelectrochemical module.
• a vertical electrochemical contact according to the present invention is generally designated by the reference numeral 20 and is constituted by two layers of catalyst 21 (for example, platinum, PEDOT, gold, CoS), respectively arranged on the conductive coating 11 of one of the two substrates 10 and the conductive coating 11 of the other substrate 10; by one layer 22, disposed on the catalyst layer 21 which in turn is located on the conductive coating 11 of the substrate 10 on which is disposed the photo-electrode 13 of the cells of the photoelectrochemical module (but which could also be located on the conductive coating 11 of the opposite substrate, the choice of the substrate 10 on which the photo-electrode 13 is disposed of the cells of the photoelectrochemical module having aesthetic reasons but not reasons of operation), said layer 22 being formed with a material having chemical characteristics (redox potential) and physical characteristics (coefficient of thermal expansion) identical to that used for the realisation of the photo-electrode 13 of the cells of the photoelectrochemical module (preferably the same material, generally a porous titanium
• Invention is separated from the cells and the flank by means of the same encapsulant 16 which laterally delimits each cell.
• the structure of the vertical electrochemical contact 20 according to the present invention is extremely similar to the structure of the photoelectrochemical cells of the same module, but has a purely resistive characteristic.
• connection path through the vertical electrochemical contact of the present invention can be modeled, taking into account the electrochemical nature of the contact, with two interface resistances (which decrease with increasing temperature) and the electrolyte ion diffusion resistance (which also decreases with increasing temperature).
• the mismatches of thermal and mechanical expansion, that typically characterise the connections made according to the solutions of the prior art, are overcome in this case by the fact that the materials used to produce respectively the cells and the vertical contact are the same. Furthermore, the contact of the two electrodes is guaranteed by the liquid electrolyte injected under vacuum.
• the process for the production of the vertical electrochemical contact 20 provides that the same can be performed through various deposition techniques (screen printing, ink jet printing, dispensing, sputtering, CVD, spray), printing a catalyst (platinum, PEDOT, gold, CoS) on the conductive coating of the two substrates that have to be coupled.
• a catalyst platinum, PEDOT, gold, CoS
• the substrate on which the layer has been deposited that will form the photo-electrode is immersed in a solution of dye according to the prior art relating to the technology of photoelectrochemical cells. Subsequently, the substrate is washed and coupled to the other substrate through the intermediary of a sealant. In the interspace between the two substrates it is then added an electrolyte to connect the two surfaces, suitably chosen in relation to the catalyst used, always according to the teachings of the prior art.
• photoelectrochemical module consists (as the corresponding devices obtainable according to the prior art) of two panels 24', 24", constituted by the substrates 10 and by the relative layers which cover them, which must be coupled together by means of the interposition of a sealant 16, between which an electrolyte 15 is inserted, containing an appropriate redox couple, responsible for the transport of charge between the two inner panels 24', 24".
• the two panels 24', 24" can be distinguished in a panel of the photo-electrode 24' and a panel of the counter-electrode 24", respectively their name being due to the fact of being covered with the material that will form the photo-electrode 13 or with the material that will form the counter- electrode 14.
• the device to be realised is actually a module with cells integrated together with the connection, on the same substrate, connected in series. This means that the final product will be in fact the composition of multiple devices (cells) divided by a connecting element (vertical contact).
• the panel of the photo-electrode 24' is constituted by an alternation of bands of T1O2 (representing the individual photo-electrodes 13 of the cells) and of catalyst (representing one of the electrodes 21 of the vertical contact 20).
• the panel of the photo-electrode 24' is then realised by printing a paste of T1O2 on the substrate 0 and, after calcination of the latter, depositing and processing the catalyst in the spaces where the Ti0 2 is not present. Areas where Ti0 2 is printed are the active areas of the device and therefore tend to occupy a greater area on the module.
• the panel of the counter-electrode 24 instead, a layer 25 of catalyst is deposited over the whole substrate 10. Subsequently, only in the zones 26 that during the coupling will result corresponding to the areas of the photo-electrode with the catalyst, the titanium dioxide is deposited, which is then calcined. Consequently, the panel of the counter-electrode 24" is constituted by areas that function as counter-electrode for the cells that are in the DSC module and by areas (those on which ⁇ 2 is subsequently printed) that function as second electrode for the vertical connection.
• Both panels 24', 24" are then immersed in the dye.
• the panels 24', 24" are coupled, through the intermediary of a sealant deposited in such a way as to isolate from each other the internal cells and the vertical connections, according to the processes of the prior art.
• the cells of the photoelectrochemical module which constitute the active areas of the module, will have a current density lower than that of the contacts (passive areas of the module). This suggests that, although one can use the same electrolyte both for cells and for contacts, it is preferable that the ionic concentration of the electrolyte of the contacts is greater than that of the cells, since the first must support a greater current density.
• a greater current density in fact, at the same concentration of the redox couple, can lead, especially at high levels of solar radiation on the module (and therefore of current), to a limitation of current inside the contact of diffusive type and, thus, to malfunctioning of the module.
• electrolyte solvents that favor the ionic transport (ie slightly viscous) and the catalysis of the species.
• the 18-nrt printable paste made by Dyesol was used for the Ti0 2 .
• the dye used is a commercial ruthenium sensitizer, known as N-719 made by Dyesol.
• electrolyte was used a commercial electrolyte with solvent based on acetonitrile (HPE-High Performance Electrolyte, Dyesol).
• the material for the catalyst is a commercial printable paste made by HCP Dyers srl.
• the encapsulant Bynel by Dupont was used and the glass was Pilkington's TEC 8.
• Figure 4 shows the trend of efficiency with the changing of temperature of a photoelectrochemical module realised according to the present invention and is equally representative of the trend of all modules produced in order to evaluate the applicability of the present invention.
• the values of efficiency are shown expressed in relation to the efficiency measured at 25 °C, taken as a reference value.
• the trend shown in the diagram allows to see an increase in efficiency of 14% as the temperature varies from 25 °C to 60°C.
• the trend shown is mainly due to the decrease of the resistance of vertical connections realised according to the present invention compared to the contacts in accordance with the prior art.
• Figure 5 shows the visual impact of the contacts according to the present invention in comparison with those made according to the prior art.
• the preferred cell interval width can be from 5 to 8mm, while, according to the thin-film technologies of the prior art, a preferred width of cell varies from 6/7mm up to 12mm, and still more preferably has a value of around 10mm .

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• 2011
  • 2011-12-07 IT IT000653A patent/ITRM20110653A1/it unknown
• 2012
  • 2012-12-07 WO PCT/IT2012/000372 patent/WO2013084254A1/en not_active Ceased
  • 2012-12-07 EP EP12813552.2A patent/EP2788996A1/de not_active Withdrawn

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