The present invention relates to a photovoltaic element, preferably used as a solar cell or the like and most preferably a flexible photovoltaic element of the Grätzel solar cell type and a novel method for continuous production of the same.
Dye Photovoltaic Solar Cell (“Grätzel-cell” or Dye PV cell) is a new kind of solar cell, which is currently being developed towards commercialisation. The Grätzel Cell converts solar radiation into electricity with remarkable efficiency exceeding 10% under standard AM 1.5 sunlight. In a Grätzel cell, a photovoltaic cell comprises a light transmitting electrically conductive layer deposited on a glass plate or a transparent polymer sheet to which a series of titanium dioxide layers have been applied, in which at least the last titanium dioxide layer (optionally also the second to last and third to last layer) are doped with a metal ion which is selected from a divalent or trivalent metal
In an enhanced version, as in U.S. Pat. No. 5,482,570, for example, which relates to a photovoltaic cell comprising a substrate having a support face having a first electrode thereon and a second electrode spaced from the first electrode by a plurality of layers including at least one layer of a semiconducting material with an active junction interface thereat, said active junction having a developed surface area greater than its projected surface area.
WO 99/66519 describes a method for manufacturing a photovoltaic element comprising a layered structure of at least a first electrically conductive layer, a layer of crystalline metal oxide semiconductor material deposited thereon, a second electrically conductive layer and an electrolytic liquid between the layer of semiconductor material and the second electrically conductive layer, wherein at least one of the electrically conductive layers is transparent and is deposited on a transparent substrate, comprising of (i) providing a layer of crystalline metal oxide semiconductor material on a first electrically conductive layer and providing an electrically conductive layer; (ii) arranging an edge zone of a thermoplastic adhesive material round the deposited layer of semiconductor material; (iii) arranging the second respectively the first electrically conductive layer over said edge zone; (iv) locally heating at least a first part of the edge zone and simultaneously exerting pressure locally on the surface of this first part to cause the adhesive to adhere to the first and second conductive layer in order to form a partially bounded space; (v) introducing an electrolytic liquid into said space, wherein the second electrically conductive layer is spatially separated by this liquid from the layer of semiconductor material; and (vi) locally heating the remaining part of the edge zone not yet heated in the fourth step and simultaneously exerting pressure locally on the surface of this remaining part to cause the adhesive to adhere to the first and second conductive layer and to enclose the liquid.
According to an enhanced method (by M. Sp{overscore (a)}th, J. M. Kroon, P. M. Sommeling, J. A. Wienke, J. A. M. van Roosmalen Netherands Energy Research Foundation ECN, and T. B. Meyer, A. F. Meyer, O. Kohle Solaronix S. A.), the working principle of a nano-crystalline dye sensitised solar cell (nc-DSC) of the Grätzel type depends on a working cycle consisting of dye excitation, electron injection into titanium dioxide and fast reduction of the oxidized dye by a redox couple. New design concepts of low and high power applications, introduced conform to market requirements, have resulted in a working nc-DSC plastic cell. A new sealing and interconnection technique is introduced which is suitable for nc-DSC high power applications.
In EP 1 087 412 is provided an electrolyte composition, comprising an electrolyte containing at least one kind of an imidazolium salt selected from the group consisting of 1-methyl-3-propyl imidazolium iodide, 1-methyl-3-isopropyl imidazolium iodide, 1-methyl-3-butyl imidazolium iodide, 1-methyl-3-isobutyl imidazolium iodide and 1-methyl-3-sec-butyl imidazolium iodide, a halogen-containing compound dissolved in the electrolyte, and a compound dissolved in the electrolyte and containing at least one element selected from the group consisting of N, P and S, the compound being capable of forming an onium salt together with the halogen-containing compound.
WO 99/66519 discloses a method for manufacturing a photovoltaic element comprising a layered structure of at least a first electrically conductive layer, a layer of crystalline metal oxide semiconductor material deposited thereon, a second electrically conductive layer and an electrolytic liquid between the layer of semiconductor material and the second electrically conductive layer, wherein at least one of the electrically conductive layers is transparent and is deposited on a transparent substrate, comprising of (i) providing a layer of crystalline metal oxide semiconductor material on a first electrically conductive layer and providing an electrically conductive layer; (ii) arranging an edge zone of a thermoplastic adhesive material round the deposited layer of semiconductor material; (iii) arranging the second respectively the first electrically conductive layer over said edge zone; (iv) locally heating at least a first part of the edge zone and simultaneously exerting pressure locally on the surface of this first part to cause the adhesive to adhere to the first and second conductive layer in order to form a partially bounded space; (v) introducing an electrolytic liquid into said space, wherein the second electrically conductive layer is spatially separated by this liquid from the layer of semiconductor material; and (vi) locally heating the remaining part of the edge zone not yet heated in the fourth step and simultaneously exerting pressure locally on the surface of this remaining part to cause the adhesive to adhere to the first and second conductive layer and to enclose the liquid. This invention does not concern structural concept according to the present invention. Moreover, this invention does not allow or suggest a continuous manufacturing method according to the present invention.
The main object of the present invention is to provide a manufacturing process for continuous production of flexible photovoltaic elements, e.g. used in solar cells, and a photovoltaic element for making solar cells.
In addition to the eminent increase of the productivity and possibility to use cheap raw material, the invention provides a number of advantages:
The invention also suggests using a spacer layer that can be adhered to surrounding layers, which makes it possible to achieve adhesion between all layers in the laminate, and at the same time to create space for the electrolyte and to avoid any contact between the lower electrode and the TiO2-layer.
The invention also suggests, besides PET, to use (a variety of) other transparent or semi-transparent thermoplastic materials, such as PE/m-LLDPE or PA, PP etc. For example, using m-LLDPE generally gives better encapsulation, better moisture barrier and is more cost efficient than PET.
Suitable polymers may be chosen partly depending on the intended use of the final cell-structure (e.g. indoor-/outdoor use, humidity). Polymers used within the cell-structure may be UV-stabilised.
The invention also suggests to coat surfaces within the cells and outside the cell with SiOx, hereby achieving several advantages, among others oxygen barrier and passivisation (i.e. for avoiding galvanic effects or various chemical reactions).
Thus, further advantages are:
Other advantages of the method(s) and the photovoltaic element(s) according to the invention are disclosed in the following description.
For these reasons a flexible photovoltaic element is provided, according to the invention, comprising at least two covering layers and a semi-material consisting of at least two electrode layers and at least one electrolyte carrier layer. The element is composed of at least two covering layers and a semi-material joined together through at least one extrusion coating and/or lamination operation of said two covering layers and said semi-material, said covering layers encapsulating said semi-material. Preferably, the element further comprises at least one layer of substantially flexible and heat-resistant substrate, which allows sintering process in high temperatures. This is of substantial importance for allowing simplified manufacturing steps of the element. The substrate is provided with substantially semi-conducting characteristics, laminated in said semi-material. In one embodiment, at least one of said electrode layers comprises of a polymeric material applied with a TCO (Transparent Conductive Oxide). The substrate can be applied with a semi-conducting material. Preferably, at least one of said electrode layers consists of a screen structure applied with a semi-conducting material. In one embodiment, at least one electrode layer consists of a substantially flexible and heat-resistant material applied with a semi-conducting material. In another embodiment, at least one electrode layer consists of a wire-screen applied with a semi-conducting material. Preferably, at least one of said electrode layers is perforated. In yet another embodiment, one electrode layer is arranged as a bottom layer and applied with a catalyst. Preferably, the semi-conducting material is applied with a dye. Between said electrode layers a spacer structure can be arranged.
The polymeric material may consist of one of PE, PET, PP or PA, said substantially flexible and heat-resistant material can consist of glass-fibre and said screen structure consists of glass-fibre or of textile. In one embodiment, the wire-screen consists of a conductive material. The TCO may consist of SnO2. The semi-conducting material may consist of TiO2. Preferably, electrolyte comprises potassium iodine or an iodine solution. The element comprises a layer of polymer coated with TCO, a substrate provided with TiO2 and a dye, a spacer provided with electrolyte and a layer of polymer coated with TCO and catalyst. At least one of said covering layers is substantially transparent, and consists of a single- or multilayer structure, comprising one or more of the following: PE-layer(s), PP-layer(s), PET-layer(s), tie-layer(s), ionomer layer(s), EAA-layer(s), EMAA-layer(s), PA-layer(s), EVOH-layer(s), SiOx-layer(s). In one embodiment, the layers in said semi material and covering layers are provided with partial adhesion between all layers prior to application of covering layers and sealing.
Preferably, in one embodiment, the photovoltaic element further comprises at least two heat-resistant layers, where two of the layers either constitute electrodes or constitute a substrate for electrode layers, and that at least one of the heat-resistant layers constitute substrate for an at least one semi-conducting layer. Preferably, at least one of said electrode layers is provided as a covering layer.
Most preferably, said layers are supplied continuously before said extrusion coating and/or lamination operation. The element is a Grätzel-cell. For electrical connection, conductive materials are applied on the outside of the cells, thereby electrically connecting the electrodes of separate cells.
According to one embodiment the electrodes, may consist of perforated metal-foil or metal-screen which can be metallized with a layer of another metal in order to be more “inert” towards the electrolyte. According to another embodiment, the polymer-based substrates may be metallized in order to achieve conductivity and thus may be used as electrodes by perforation if used as upper electrode. According to one embodiment, the electrolyte-impregnated spacer layer, e.g. paper or foamed polymer, may be laminated into cells, which can be used in applications in which adhesion between layers is not necessary. Hereby the injection step can be avoided.
The invention also relates to a method of producing a flexible photovoltaic element, the method comprising the steps of: providing a semi-material consisting of at least two electrode layers and at least one electrolyte carrier layer, providing at least two covering layers, joining together said at least two covering layers and said semi-material through at least one extrusion coating and/or lamination operation for composing said element, whereby said covering layers encapsulate said semi-material through said extrusion coating and/or lamination operation. Preferably, said at least two covering and electrode layers and at least one electrolyte carrier layer are supplied continuously. The method further comprises the step of providing at least one layer of a heat resistant substrate and/or a spacer layer before lamination. The method also comprises the step of providing said substrate with TiO2. The method also comprises an injection step of an electrolyte in said electrolyte carrier layer. Preferably, the substrate and/or a spacer layer is said electrolyte carrier. The method also comprises cutting cell structure into smaller cell units. Preferably, the method is speeded by producing said electrode layers in a second parallel process.
The injection step comprises the steps of: arranging a hole during the lamination in a bottom sealing film, injecting by an injector under a pressure the electrolyte through the hole, the electrolyte filling a spacer and some of the bottom electrode and the substrate due to capillary forces, and arranging a thin film over said hole and melting it together with the film. The method also comprises the steps of: providing a through hole through the cell layers, filling said hole with electrolyte, which is distributed to the spacer, and providing a sealing with riveting or by thin films applied on each side of the laminate. The covering means is a film or foil. The method also comprises rolling said substrate together with said heat-resistant spacer layer, which prevents contact between the rolled up substrate layers and allows for hot air to pass between the substrate layers. Said roll is exposed to hot air, e.g. by being inserted into an oven, where in a drying and sintering of TiO2 is performed.
In the following, the invention will be further described in a non-limiting way under reference to the accompanying drawings in which:
a and b are schematic cross-sectional views illustrating a part of a conventional photovoltaic element and an element according to the present invention, respectively,
a, 15b, 15c schematically illustrate a multi-lane laminate structure production.
The main idea of the present invention is to present a method for mass production of flexible solar cells, such as Grätzel cells, and construction of flexible polymer-based cells. The manufacturing process can be compared to, e.g. packaging lamination technique. The invention also comprises using a combination of special type of materials, which allows the special and continuous production process different from the prior art technique.
Moreover, main principle of one variant of the production method is to separately produce flexible, continuous electrode layers, semi-conducting layer and in some cases a spacer layer, and heat laminate/extrusion coat the layers together with various polymer films into a flexible and continuous laminate (semi-material), which is cut into pieces and laminated in-between two films or a film and a foil, whereby the pieces are encapsulated and thereby sealed cells are produced. If the semi-material does not contain electrolyte (e.g. as a gel), the electrolyte is injected in the cells after sealing. By using this principle, the following advantages are achieved:
a and 1b show cross-sections through two cells for illustrating the differences between a conventional Grätzel cell element and an element produced according to the invention.
The conventional cell element 100a comprises a layer 101a of glass, provided with SnO2, constituting the electrode layer 102a, a layer 103a of TiO2 sensitised with a dye, an electrolyte layer 104a and a layer 106a of glass provided with SnO2, constituting the electrode layer 105a, and catalyst.
The exemplary cell element 100b according to the invention comprises a layer 101b of polymer coated with TCO, where the TCO, i.e. layers of 102b and 105b constitutes the electrodes, a substrate 103b provided with TiO2 (or other semi-conducting material) and sensitised with a dye, a spacer 104b provided with electrolyte and a layer 106b of polymer,-coated with TCO and catalyst, or conductive foil. Application of TiO2 on a heat resistant substrate allows flexibility and provides better efficiency and capacity.
The first layer 2012 and the second layer 2032 are then joined, as a third layer is applied on top of the first layer 2012 by extrusion coating or heat lamination (14) to a package 213. Also, the second face 2063 of the cell structure comprising a polymer film 206 is provided (15) with TCO 2061, provided (16) with a catalyst 2062 and perforated (17). The second face structure is joined with the package 213, as an additional layer is extrusion coated or heat laminated at the outside of the second face structure with a spacer 208 between the package 213 and the second face 2063, building the cell structure 200. The dye sensitisation can be done after step (14) to prevent harming the dye.
As it appears from the drawing, the packages 213 and 2063 are displaced relative each other, which allows sealing of the edges in the machine direction during step (43) and (46). Otherwise, the sealing in the machine direction and in the cross-direction is performed in the final lamination step (19), after cutting (18). Finally, the encapsulated cell structure is injected with electrolyte (20).
Using (a) heat-resistant substrates for the TiO2 and for the TCO, which preferably consists of glass-fibre, has many advantages, amongst others it allows:
The remaining process steps are substantially the same as described in connection with
The bottom layer 4063 comprises a screen of heat-resistant material 406, such as glass-, or metal-foil, which may be SiOx-coated and coated (44) with SnO2, and provided (45) with a catalyst and extrusion coated or heat laminated (46) with a polymer layer to constitute the cell structure 400. Between the package 413 and the electrode layer 4062, a spacer layer 408 can be applied during the extrusion coating or heat lamination operation (46). Further production steps (18-20) are performed as described above in connection with
In another alternative process, as illustrated in
The bottom layer 506 comprises a conductive substrate 5061, such as a metal foil, which may be provided with SnO2 5062 in a first step (55) and provided with a catalyst 5063 in a second step (56) before it is extrusion coated or heat laminated (57) with a polymer layer. The remaining steps are similar to the described method in conjunction with
A more detailed production process is illustrated in
In process step A, a flexible, heat-resistant substrate, of types mentioned above, which can be surface treated is rolled off a cylinder 701 and may be passed through a process step 702 in which a thin layer of TCO, i.e. SnO2, is applied. Then 703 is provided with TiO2, e.g. dissolved in ethanol or it is coated 703b with paste of TiO2 before it is dried. The substrate is dried in an oven 704, which sinters it at about 450° C. for some hours (e.g. 3-4 h). During the sintering the substrates is moved slowly up and down between cylinders. The substrate after the bath is passed through a dye bath 705 and then a water bath 706 and an ethanol bath 707a. It may also be sprayed 707b with ethanol. Finally, the substrate 708 is rolled on a cylinder, for storage in an air-proof and dark compartment until it is needed for next process step. Instead of passing through different baths the materials can be sprayed onto the surfaces.
An alternative way (alternative to process step 704) to sinter the TiO2, applied on a substrate, may be to roll up the coated substrate on a roll together with a heat resistant spacer layer (e.g. a screen), which hinders contact between the rolled up substrate layers and allows for air to pass between the substrate layers. Thereafter the roll may be exposed to hot air, e.g. put into an oven, where the drying and sintering of the TiO2 is taking place.
In the parallel process step B, electrodes 709 are produced (upper electrode, 709a and lower electrode, 709b). A substrate 714 is applied 711 with a TCO. If the substrate 714 is heat resistant, the TCO may be SnO2. Non-heat resistant substrates may be for example a transparent, flexible polymer film and heat resistant substrates may be a screen structure, made of glass-fibre, heat resistant polymer or textile. If the substrate is a film, perforation is done in step 715. If the electrode is going to be used as lower electrode (709b) it is additionally provided with a thin layer of catalyst in step 716.
In process step C the lamination is carried out. In first lamination, the top electrode 709a (polymer film, screen, heat resistant or non-heat resistant substrate, with or without a layer of TCO) is laminated with the substrate 708. It is carried out in a nip 710, either by extrusion coating 711 a polymer on the outside of the top electrode or by heat laminating the polymer film 206 on the outside of the top electrode 709a. In the latter case either a hot cylinder nip 710b or exposure to heat, e.g. by means of IR heater 710c, flame/burner 710d or other heating source, is used. The polymer film may have a thermoplastic adhesive layer, e.g. of ionomer, EM or EMAM facing the heat source. This can be used in any of above described embodiments for creating necessary conditions for later edge-wise sealing in the coming lamination step. In case the spacer screen is used in the cell structure and it is going to be laminated in the structure in the second lamination (see below) and no adhesion is wanted between layers within the laminate 714, the external layers are extrusion coated/heat laminated in first and second laminations, in such way that they overlap the structure and automatically produce alongside sealing.
The second lamination means that the laminate 712 is (according to above) laminated with the bottom electrode 709b.
The second lamination is carried out in a nip 717, where the laminate 712 exposed to heat is laminated to the bottom electrode 709b, possibly with a spacer 713, e.g., made of a flexible, insulating layer through which an electrolyte can pass, such as polymer screen, textile, paper, (polymer coated) glass fibre screen, SiOx- or polymer coated metallic screen. In order to better adhere to surrounding layers, the spacer screen may be impregnated or primed with a thin priming layer, which may consist of a thermoplastic polymer. The spacer may also comprise of porous perforated paper. The heat can be provided by extrusion coating 718a the polymer outside the bottom, electrode 709b and in that way adhering the layers to each other. If no spacer is used, the substrate and the bottom electrode are laminated together directly, in which case heat is provided by extruding 718b the polymer outside the bottom electrode; thus, the bottom electrode is penetrated and mechanical adhesion to substrate is generated. Alternative lamination may include heat supply in a hot cylinder nip 718c, where a cold polymer film 719 is heat laminated outside the bottom electrode (with or without spacer), or heat lamination on the outside of the bottom electrode through other heating of the polymer film 719, e.g. by means of a heating source 718d or flame/burner 718e. The polymer film may have a thermoplastic adhesive layer of e.g. ionomer, EM or EMAA facing the heat source. Another alternative is to substitute the spacer 713 with a foamed polymer having open cells, which is extruded 718f between the substrate and the bottom electrode with or without cold polymer film on the outside of the electrode 709b.
According to
An alternative way to perform process step D may comprise two steps of extrusion coating. In this case, the polymer film 722a is only used as a carrier of the portions 721b, adhered onto the surface of the polymer film 722a, which does not take part in alongside sealing of the cells. After adhering the film portions 721b on the carrier film 722a, extrusion coating (725a) is performed in two steps, according to previous description, sealing the cells by encapsulation, whereby the cells are sealed on all four sides, letting the electrodes pass through the alongside seals.
Yet another way to perform process step D is to proceed according to the latter description, but instead of extrusion coating the covering layers, they may be extrusion laminated (i.e. cold polymer films are adhered to the film portions 721b by extruded hot polymer films, applied in-between the cold polymer films and the film portions).
All polymer films mentioned above, which are used as covering layers (722a, 722b and polymer films applied in steps 725a-d), and which are intended to seal to other materials, may have a layer of thermoplastic adhesive polymer, e.g. ionomer, EAA or EMM, facing the side to be sealed, and all PE-layers may be substituted with other thermoplastic polymers, e.g. with PET-layers. The polymer films may not only consist of five-layer structures, they may consist of one or more layers. E.g. by using two-layer structures, one of the layers may be a thermoplastic adhesive polymer (e.g. ionomer), and the other layer in the two-layer structure may be a polymer (e.g. PE) different from the polymer (e.g., PET) in the layer to be sealed against.
In the final process step, i.e. step E, the electrolyte, e.g. consisting of potassium iodine-iodine solution, is injected 727 in the laminate portions 724. This is done by means of, e.g. rotating cylinders (described below) having injection nozzles. The injection is done in the spacer layer. It is also possible to add the electrolyte before the sealing. Eventually, the injection openings are sealed 729 with a film 731a or hot-melt 731b and pieces may be cut 732.
All the laminated films can be surface treated, for example through flame treating or corona, to create better conditions for adhesion. Moreover, all films or screens coated by SnO2 or working as the exterior of the cell or in contact with the electrolyte may be coated with SiOx. Additionally, all metal-foils used as electrodes may as earlier described be coated with SiOx and then with TCO, e.g. SnO2, but may also be uncoated, if certain metals are chosen.
The final cell structure may be laminated onto a tensile stress resistant substrate, which may be flexible (e.g. made of glass-fibre or metal foil).
The sealing devices 98 arranged on a second cylinder 94 are of hot melt type and comprise an outlet 95 for delivering melt film to the section to be sealed.
According to the first example:
According to the second example:
As it is illustrated in
The electrical connection may be performed by applying conductive materials, such as foil, tape, wire or print on the outside of the physically connected cells, thereby electrically connecting the electrodes of the separate cells. The electric connections may be easily changeable/moveable, thereby changing the electric circuits. On the electric connections, conductive wires may be applied, in order to connect the cell-structure to the load to be supplied by electricity.
Earlier described process, refers to a single-lane based semi-material. It is also possible to produce a multi-lane based semi-material. By the method described as follows, it is possible to manufacture a very long “semi-material”, consisting of several, continuously connected “endless” cells, which are connected in series. Advantages with this multi-lane process compared to the previously described single-lane based process, is that the number of process steps are reduced, that a separate process step for contacting is avoided as contacting is automatically achieved as an integrated part in the process and that the “semi-material” easily can be produced in large rolls and thereafter be cut and sealed in cross-direction in suitable length. The filling of the cells will also be different. In the case of multi-lane process, the process-integrated series-connection means that the voltage level will be determined by the number of lanes, thereby it will not be adjustable in the same way as may be possible with the one-lane concept.
The multi-lane concept is schematically described in
One example of the multi-lane process is described in the following:
Thereafter the “semi-material” is cut into pieces of suitable length (8-4). The films, which constitute the encapsulation, can consist of a combination of polymers as earlier mentioned in the description of the single-lane concept. If extrusion coating is used for encapsulation, the edges can be made even with the method described in
As an alternative solution to the above described process for producing a laminate structure with cells in series, instead laminate-structures with a single cell may be produced, whereafter the laminate-structure is connected/joined with other laminate-structures, in order to form a laminate-structure consisting of cells connected in series.
The cell according to the invention can have many applications, but the flexibility and mobility allows also using it as emergency device, e.g. for charging car batteries, camping energy source etc.
As mentioned above, the invention suggests using as the semi-conducting layer a flexible, heat resistant substrate (i.e. glass fibre, (SiOx-coated) perforated metal), on which TiO2 is applied. Thus, it is possible to sinter the TiO2 at, e.g. 450° C., which is preferable with respect to function and efficiency. In contrary to prior art, the heat resistant substrate is not used as lower electrode, as this means that the electrolyte layer has to be applied partially between the semiconductor and the source of light, this decreasing efficiency.
Some advantages using metal-foil as electrodes are, except from the possibility to sinter the TiO2 at high temperatures, to be able to avoid ITO as conducting layer and cost efficiency, also that conductivity is better than for ITO-coated PET, meaning that it is easier to produce cells with larger surface areas. In order to secure best functionality of the heat-resistant electrodes, the following may be done:
The upper electrode, which is perforated or will be perforated at some point during the production, may consist of a substrate of metal-foil, e.g. aluminium-foil, in order to be heat-resistant. On the upper side the semi-conductor, e.g. TiO2 is applied. Between the metal-foil and the TiO2, a thin layer of another metal may be applied by metallization or a thin layer of SnO2 may be applied in order to avoid contact and thereby interaction between the metal-electrode and the electrolyte. Between the thin metal-layer or SnO2-layer, a thin layer of SiO, may be applied in order to secure adhesion between layers. On the back-side of the metal-foil a thin SiOx-layer or a polymer layer may be applied in order to avoid direct contact between the electrodes and/or to avoid interaction between the electrolyte and the back-side of the upper electrode.
The lower electrode may consist of a substrate of metal-foil, e.g. aluminium-foil in order to be heat resistant. On the metal-foil a catalyst is applied, e.g. a thin layer of Pt or C. Between the metal-foil and the catalyst, a thin layer of SnO2 may be applied. Between the SnO2-layer and the metal-foil, a thin layer of SiOx may be applied.
The invention also suggests using as the electrode layers flexible, heat-resistant substrates (i.e. glass fibre screen, or (SiOx-coated) metal-screen), which are coated with TCO. As the substrates are heat-resistant, the TCO used can be SnO2, which is preferred with respect to the functionality and efficiency.
The invention also suggests using one single substrate both as upper electrode and as the substrate for the semi-conducting layer. This may be done by first applying the TCO-layer (e.g. SnO2) on the substrate, thereafter applying the TiO2-layer on top of the TCO-layer.
The invention also suggests performing a second sealing/encapsulation operation with different sealing techniques, in order to further strengthen the seal around the cell.
The invention also suggests that heat resistant electrodes, e.g. consisting of perforated metal-foil or metal-screen may be metallized with a thin layer of another metal in order to be more “inert” towards the electrolyte.
The invention also suggests that polymer-based substrates may be metallized in order to achieve conductivity. They may be used as electrodes by perforation if used as upper electrode.
The invention also suggests that other carriers than gels may be used for the electrolyte. An electrolyte-impregnated spacer layer (e.g. paper or foamed polymer) may be laminated into cells used in applications in which adhesion between layers is not necessary. Hereby the injection step can be avoided.
Dye photovoltaic (dye-PV) cells generally have several advantages related to their application. Flexible Dye-PV cells specifically have several additional advantages. As the cells are coming out from the production process, they are “endlessly” physically connected to each other and possible to roll up on a roll. From this roll, end-products can be cut, consisting of several physically connected cells, which might be electrically connected in series or in parallel, depending on use. They might also be used as single cells. Thus, they are: suitable for light poor environment, such as indoors use or cloudy areas, rollable cells are obtained, flexibility of the cells allows easily foldable, easily transportable and easily storable end-products and they provide possibility to adjust at least one of current or voltage in a simple way.
Electrical connection can be performed by applying conductive materials, such as foil, tape, wire or print on the outside of the physically connected cells, thereby electrically connecting the electrodes of the separate cells, the electric connections being easily changeable/moveable, thereby changing the electric circuits and on the electric connections, conductive wires being applied, connecting the cell-structure to the load to be supplied by electricity.
The invention is not limited to the shown embodiments but can be varied in a number of ways without departing from the scope of the appended claims and the arrangement and the method can be implemented in various ways depending on application, functional units, needs and requirements etc. In some cases, for example, TCO can be applied through evaporation. Moreover, if semi-conducting material is used, it can be screen-printed on the substrate or the upper electrode.
Number | Date | Country | Kind |
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0103740-7 | Nov 2001 | SE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/SE02/02049 | 8/11/2002 | WO |