Coating processes – Electrical product produced – Photoelectric
Reexamination Certificate
2001-11-30
2003-11-25
Diamond, Alan (Department: 1753)
Coating processes
Electrical product produced
Photoelectric
C438S061000, C438S062000, C438S064000, C438S067000, C438S080000, C438S085000, C136S244000, C136S245000, C136S251000, C136S263000, C257S043000, C257S433000, C257S431000, C429S111000
Reexamination Certificate
active
06652904
ABSTRACT:
TECHNICAL FIELD
This invention relates to single cell and multi-cell regenerative photovoltaic photoelectrochemical (RPEC) devices, and to materials and methods used for manufacture of such devices.
Examples of the RPEC cells of the type concerned are disclosed in the following U.S. patents.
U.S. Pat. No. 4,927,721, Photoelectrochemical cell; Michael Graetzel and Paul Liska, 1990.
U.S. Pat. No. 5,350,644, Photovoltaic cells: Michael Graetzel, Mohammad K Nazeeruddin and Brian O'Regan, 1994.
U.S. Pat. No. 5,525,440, Method of manufacture of photo-electrochemical cell and a cell made by this method; Andreas Kay, Michael Graetzel and Brian O'Regan, 1996.
U.S. Pat. No. 5,728,487, Photoelectrochemical cell and electrolyte for this cell; Michael GraetzeL Yordan Athanassov and Pierre Bonhote, 1998.
BACKGROUND TO THE INVENTION
RPEC cells, as of the type disclosed in the above patents, are capable of being fabricated in a laminate arrangement between two large area substrates without undue expense. One typical arrangement involves two glass substrates, each utilising an electrically conducting coating upon the internal surface of the substrate. Another typical arrangement involves the first substrate being glass or polymeric and utilising an electrically conducting coating upon the internal surface of the substrate, with the second substrate being polymeric. In some arrangements, the internal surface of said second polymeric substrate is coated with an electrically conducting coating, whereas in other arrangements, said second polymeric substrate comprises a polymeric foil laminate, utilising adjacent electrically conductive material, such as carbon. Also, in some arrangements, the external surface may be a laminated metal film, and in other arrangements, the external surface may be coated by a metal. At least one of said first and second substrates is substantially transparent to visible light, as in the attached transparent electrically conducting (TEC) coating. RPEC cells contain a photoanode, typically comprising a ruthenium dye-sensitised, nanoporous semiconducting oxide (eg. titania) layer attached to one conductive coating, and a cathode, typically comprising a redox electrocatalyst layer attached to the other conductive coating or conductive material. An electrolyte containing a redox mediator is located between the photoanode and cathode, and the electrolyte is sealed from the environment. If one or more polymer substrates are utilised, the photoanode and the cathode are typically electrically separated by a porous insulating layer (eg. insulating ceramic oxides) or spacer(s) (eg. insulating spheres). TEC coatings, which usually comprise a metal oxide(s), have high resistivity when compared with normal metal conductors, resulting in high resistive losses for large area RPEC cells operating under high illumination. When operating under high illumination, one method to minimise these losses is the deposition of one or more networks of electrically conductive material that serve to collect and/or distribute electrons in the cell. Another method to minimise these losses is by connecting a multiple of RPEC cells (here called ‘RPEC modules’) in series to generate higher voltages and to minimise total current. Such connections in RPEC modules may be made externally or internally (International Application PCT/AU00/00190). To enable internal series connection of adjacent RPEC cells, selected areas of such conducting coatings must be electrically isolated, portions of such areas overlapped when laminated, interconnects used to connect such overlapped areas and electrolyte-impermeable barriers used to separate the electrolyte of individual cells.
One example of the manufacture of an RPEC module involves the use of two glass substrates that have TEC-coatings that have been divided into electrically isolated regions. Titanium dioxide (or similar semiconductor) is screen printed onto selected areas of the TEC coating of one substrate and an electrocatalyst is screen printed onto selected areas of the TEC coating of the other substrate. The titanium dioxide (titania) is coated with a thin layer of a dye by immersion of the titania-coated substrate in the dye solution. Strips of sealant and interconnect material are deposited upon one of the substrates and the two substrates are then bonded together. Electrolyte is added to the cells via access apertures in one of the substrates and these apertures are then sealed.
Another example of the manufacture of an RPEC module involves the use of one substrate with a TEC-coating that has been divided into electrically isolated regions. Successive layers of titania, insulating ceramic oxide, and conducting catalytic material (for example, carbon-based) are deposited, for example by screen printing, onto selected areas of the TEC-coated substrate, with the catalytic layer also serving as an interconnect. The titania is coated with a thin layer of the dye by immersion of the multiple-coated substrate in the dye solution. Electrolyte is added to the spaces within the porous titania-insulator-catalytic layers. The sealant face of a sealant/polymer and/or metal foil laminate is sealed to the substrate.
One of the difficulties in the manufacture of RPEC cells and modules is that when the semiconducting oxide-coated substrate is exposed to the dye solution, dye not only adsorbs to the semiconducting oxide, but also to the conductive coating. Similarly, if sealant has been applied to the semiconducting oxide-coated substrate, exposure to the dye solution typically results in dye adsorption to the sealant surface. The adsorbed dye on the conductive coating or sealant can interfere with the strength and/or permeability of any bond made to these surfaces during sealing, and also can affect the performance and service life of the RPEC cell. One process that prevents dye adsorption to the conductive coating involves covering relevant areas of the conducting coating with a polymeric film, application of dye to the coated substrate and then removal of the polymeric film, thus leaving a clean conductive coating surface to which a subsequent seal may be made. Another process that prevents dye adsorption to the conductive coating involves use of a laminated film (eg. surlyn/polypropylene) in which one face (eg. the surlyn face) is sealed to the relevant areas of the conducting coating, after which the dye is applied to the coated substrate and then the upper layer (eg. polypropylene) is removed, thus leaving a clean polymer (eg. surlyn) surface to which a subsequent seal may be made. This subsequent seal may involve additional sealant material or may involve-sealing directly to the sealant surface, with the seal being made to a coated glass substrate or to a polymeric foil laminate, such as surlyn/aluminium. Unfortunately, these protective film processes are inconvenient and time consuming and can result in variability in performance of the RPEC. An additional impediment to a continuous manufacturing process is that dye application to the semiconducting oxide needs to be automated to be carried out efficiently, preferably within a low volume container that may be dark, heated, and provided with a partially sealed, low-oxygen content atmosphere.
SUMMARY OF THE INVENTION
The present invention provides a method for manufacturing regenerative photoelectrochemical (RPEC) devices in a production line, each device being deposited on a substrate, the method comprising the steps of:
attaching at least one substrate to the protective film in such a way that a predetermined areas of the substrate are protected from being coated during at least one subsequent manufacturing process;
The protective film may comprise a patterned composite, laminated or multilayer film (CLM film) and the substrate may be a multiply-coated substrate of RPEC cells and modules. The protective film may be patterned to create apertures, which are used as engagement means and the step of transporting the substrate comprises penetrating the engagement means with teeth to locate and mechanically enga
Hopkins Jason Andrew
Phani George
Vittorio David
Diamond Alan
Ostrolenk Faber Gerb & Soffen, LLP
Sustainable Technologies International Pty. Limited
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