Active solid-state devices (e.g. – transistors – solid-state diode – Housing or package – With contact or lead
Reexamination Certificate
2002-02-04
2003-12-16
Flynn, Nathan J. (Department: 2826)
Active solid-state devices (e.g., transistors, solid-state diode
Housing or package
With contact or lead
C257S439000, C257S700000, C257S431000, C438S048000, C438S054000, C438S069000
Reexamination Certificate
active
06664623
ABSTRACT:
TECHNICAL FIELD
This invention relates to single cell and multi-cell regenerative photoelectrochemical (RPEC) devices, materials and methods used for electrical connections for such devices, and materials and methods used for sealing electrical connections and electrical networks in such devices.
Examples of the RPEC cells of the type concerned are disclosed in the following US 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 Piere 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 is the attached transparent electrically conducting (TEC) coating. RPEC cells contain a photoanode, typically comprising a dye-sensitised, nanoporous semiconducting oxide (eg. titanium dioxide known as 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.
Many RPEC single cell and module designs would be advantaged by an increased size of individual RPEC cells. However, such 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, which affects the efficiency of the RPEC device especially in high illumination conditions. These losses can be reduced by the use of a pattern of electrically conductive material (ECM) in the form of bus bars, pads, grid of lines or any other pattern on the TEC coating(s). Conduction of electrons into and out of RPEC cells via the electrically conductive material typically necessitates penetration of the sealing of said cells by the electrically conductive material. Such penetration often presents difficulties in maintaining the hermetic sealing of said cells. The dominant selection criteria for the electrically conductive material deposited upon the TEC are cost and conductivity, so the selected material is commonly chemically reactive towards the electrolyte of the RPEC cells. Whilst this problem can be overcome by application of a sealant over the electrically conductive material the effectiveness of this seal is often compromised by the surface roughness and/or the porosity of the conductive coatings, especially with respect to TEC coatings. The inability of the sealant to completely fill the surface roughness and/or pores of the conductive coatings, especially with respect to TEC coatings, can lead to corrosion of the electrically conductive material and/or to degradation of the electrolyte, thereby reducing the performance of the cells.
OBJECTIVES OF THE INVENTION
It is an objective of this invention to provide materials and methods for electrical connections for use with RPEC cells and RPEC modules that will overcome the above-mentioned disadvantages in the art. It is a further objective of this invention to provide materials and methods for hermetic sealing of electrically conductive material in RPEC cells and RPEC modules that will overcome the mentioned disadvantages in the art.
OUTLINE OF THE INVENTION
This invention provides for electrical connections to be made to said electrically conductive coating (including TEC) and/or to said electrically conductive material (ECM) via holes in one or both of the substrates, thereby eliminating the need for said electrically conductive coating and/or said electrically conductive material to penetrate the hermetic seal of RPEC cells and modules.
This invention also provides for the deposition upon said TEC of a network of said electrically conductive material with an underlayer of protective material to seal the surface of the TEC and with an overcoat layer of protective material. The thickness of the underlayer and correspondingly the electrical conduction path length in the underlayer is negligible in comparison to that in electrically conductive material. The underlayer material is selected to be chemically inert towards the electrolyte of the RPEC cell. Such network of said electrically conductive material is particularly advantageous for efficient collection and distribution of electrons in RPEC cells.
In order to maximise light exposure for solar cells and to minimise costs, it is of particular importance to minimise the surface area covered by patterns of said ECM. Significant effort has been expended to design electrically conducting material patterns to minimise said material costs and to minimise said covered surface area. It is a feature of this invention that location of said electrical connections of the invention may be made wherever appropriate, thereby providing a wide range of flexibility in said pattern design and hence a wide range of device layouts. For example, a star-shaped busbar design layout could utilise a single central electrical connection of the invention compared to the four penetrations of the seal required by a conventional design of the same said covered surface area which would comprise an inverse shape for each arm of the star. Alternatively, said conventional design of the same said covered surface area could be connected by four electrical connections of the invention, similarly avoiding four penetrations of the seal. This invention anticipates a wide range of alternative layouts of said electrically conducting material including the use of small lines connected to busbars. Whilst not limited to such substrates, the invention is particularly suited to providing electrical connections to said ECM deposited upon electrically conducting coatings on glass substrates, including transparent electrically conducting (TEC) coatings. Additionally, this invention provides for external electrical connection of RPEC cells in series and/or parallel to realise well-known advantages of performance and reliability.
According to one aspect of the invention, an RPEC cell, that comprises in part, firstly one substrate that is successfully coated with transparent electrically conductive coating, a dye-sensitised, nanoporous semiconducting oxide, electrically insulating layer, catalytical layer and electrically conductive layer and secondly another substrate, whereby one or both of said substrates is substantially transparent to visible light, and one or more holes are made through one or both substrates to provide electrical connection to said electrically conductive coating and/or electrically conducting layer. In the case where an ECM pattern is deposited on to electrically conductive coating and/or ele
Hopkins Jason Andrew
Phani George
Skryabin Igor Lvovich
Vittorio David
Flynn Nathan J.
Ostrolenk Faber Gerb & Soffen, LLP
Sustainable Technologies International PTY Ltd.
Wilson Scott R
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