HK1201375B - Method for manufacturing dye-sensitized solar cells and solar cells so produced - Google Patents

Description

Method for manufacturing dye-sensitized solar cell and solar cell manufactured thereby

Technical Field

The present invention relates to a method for the preparation of a dye-sensitized solar cell DSC comprising at least one electrode with a porous conductive powder layer, and said DSC having improved electrical properties.

Background

There is an increasing demand for lower cost photovoltaic solar cells.

From M Grthe dye-sensitized solar cell (DSC) developed by tzel et al is a new type of solar cell made of low cost materials and can be manufactured by conventional printing techniques, see for example US 5084365.

Conventional DSCs have porous TiO of a few microns thick deposited onto a transparent conductive substrate₂A working electrode layer. TiO 2₂The working electrode comprises a metal oxide layer formed on the TiO₂Interconnected TiO dyed by adsorption of dye molecules (usually polypyridyl ruthenium complexes) on the surface of the particles₂And (3) granules. The transparent conductive substrate is typically a Transparent Conductive Oxide (TCO), such as fluorine doped tin oxide (FTO), deposited onto a glass substrate. Other types of TCO materials may also be used, such as Indium Tin Oxide (ITO), or zinc oxide doped with aluminum, or tin oxide doped with antimony. TCO layerFunctioning as a back contact from dyed TiO₂The working electrode extracts the photo-generated electrons. TiO 2₂Electrodes and electrolytes (usually containing I)^-/I₃ ^-Ion pair) and another transparent conductive substrate (i.e., a counter electrode). The TCO layer of the counter electrode is usually covered with a thin platinum catalyst layer. Platinum has a strong catalytic effect, promoting the transfer of electrons to the electrolyte.

Generally without TiO₂The electrode material deposits the edges of the conductive substrate. The two conductive substrates are sealed at the edges to protect the DSC components from the surrounding atmosphere and to prevent evaporation or leakage of the DSC components within the cell.

Incident light from dyed TiO through TCO₂The working electrode generates photo-generated electrons. TCO has a light-blocking effect because it absorbs part of the incident light and thus reduces the light from reaching the dyed TiO₂The amount of working electrode. The increased transparency of the TCO results in lower conductivity and vice versa. It is impossible to have both high transparency and high conductivity.

Due to the low conductivity of the transparent conductive oxide TCO, the cell must be deposited in sections or ribbons with gaps between them. Current collectors are deposited in the gaps to connect the segments or ribbons, thereby forming a solar cell module. The wider the segment, the greater the ohmic loss of electrons in the TCO layer due to poor TCO conductivity.

The individual cells are electrically connected in parallel or in series to boost the DSC current or DSC voltage, respectively. The electrical connection can be made outside the cell using peripheral devices such as cables or solder. Alternatively, the electrical connections can be made within the cell by distributing the DSC components in such a way as to achieve the parallel or series connections required for the cell.

The low conductivity of the transparent conductive oxide TCO is a problem because it limits the width of the segment. Another problem is that TCO-based glasses are expensive and the use of two TCO-based glasses in DSC construction increases the cost even further. In order to solve these problems, attempts have been made to form a film on TiO by employing a technique using metal sputtering₂Vacuum deposition of a conductive metal layer on the working electrode displaces the TCO-based glass that was in contact after. Because the deposited sputtered metal layer is conductive, the TCO-based glass can be replaced with a much less expensive TCO-deficient glass.

Electrospray of tetrapod-shaped ZnO to TiO is described in Yohei Kashiwa, Yorkazu Yoshida and Shuzi Hayase, PHYSICS LETTERS92,033308(2008))₂On a layer, followed by TiO coated with ZnO₂The upper portion of the layer is sputtered with titanium metal. The tetrapod-like ZnO embedded in the titanium layer was then washed away by subsequent dissolution of the ZnO in HCL to form a sufficiently porous titanium layer. The porosity of the titanium layer must be sufficient so as not to create electrolyte ion confinement with resistive losses as a result. Furthermore, the dye sensitization process can be mitigated due to diffusion problems through the titanium layer.

Yohei Kashiwa, Yorkazu Yoshida and Shuzi Hayase, PHYSICS LETTERS92,033308(2008)) and US2009314339 describe methods for increasing the porosity of vacuum deposited metal layers. In US2009314339 on porous TiO₂Forming a fine particle layer on a surface of the layer and then forming a conductive metal film on the surface of the fine particle layer; and thereafter removing the fine particle layer by heating or solvent washing. Sputtering and vacuum deposition of metal layers are very expensive and slow methods that are not suitable for large-scale production of large areas. Furthermore, it is also impossible to form a layer having a sufficient thickness and porosity by these methods.

Other attempts have been made to reduce the internal resistance of the back contact by placing the back contact on the side of the working electrode opposite the incident light and forming the back contact with a porous metal film in contact with the working electrode.

In EP1708301 a dye-sensitized solar cell is described which is made by printing an alumina green sheet substrate and thereafter providing a second current collector electrode by screen printing a paste containing tungsten particles to a thickness of 1-10 microns, and screen printing a conductive film of a metallised ink containing platinum over the second current collector electrode (counter electrode). Another alumina green sheet for the insulating layer is formed by screen printing an alumina paste onto the conductive film. A first current collector electrode (back contact) was applied to the green alumina sheet layer by screen printing a tungsten containing paste. Thereafter, the green layered body (lamina) was sintered at 1500 ℃ in a reducing atmosphere, and then a titania electrode layer was printed on the sintered stack, after which the cell was sealed.

The second current collector electrode need not be a printed layer but may be replaced by a metal substrate. The metal may be tungsten, titanium, nickel, platinum, gold or copper.

Other metals such as titanium or nickel may be substituted for the tungsten particles in the paste. A pore-forming oxide material may be included in the paste to ensure a porosity of 10-30% so that the electrolyte may be distributed in the porous material.

Screen printing of substrates is a slow process that often results in defects such as pinholes in the material, which makes it difficult to print a conductive metal layer onto a green substrate.

The printed stack was bulk sintered at 1500 ℃. A high sintering temperature may be required to achieve a sintering effect between the tungsten particles.

In addition to the cost of heating, high temperatures also require that the battery contain certain materials that can withstand high temperatures. Sintering at high temperatures also incorporates the risk of contaminating the conductive material and thus deteriorating its conductive properties.

In WO2011096154 a sandwich type dye-sensitized solar cell is described with a porous conductive metal layer formed on a glass cloth or cellophane substrate. The porous metal layer may be formed by sputtering or by printing a paste containing titanium particles to a thickness of 0.3-100 microns. The titanium dioxide paste was reverse-printed onto the porous conductive metal film and calcined at 400C until the desired thickness was obtained. A transparent resin sheet was then bonded to the titanium dioxide electrode. The other resin sheet was provided with a transparent conductive film with a thin sputtered layer of platinum and was placed on the top side of the glass cloth and provided with electrolyte and sealed the cell. The fine metallic titanium powder used is very expensive and the steps for preparing the battery are complicated.

Another problem with the above solution relates to the metal particles used to form the electrodes. Tungsten particles and titanium particles have a thin oxide layer on the surface, which weakens the electrical contact between the particles.

A method for preparing a dye-sensitized solar cell comprising a back electrode with a porous conductive powder layer and a counter electrode is shown in PCT/EP2011/067603 (not disclosed), where a porous conductive powder layer can be prepared by printing a powder of a metal or metal hydride and then compacting the powder layer to achieve contact between the particles. The hydride particles are heat treated after compaction to convert the hydride to a metal. Further heat treatment is optional.

The compaction step is expensive and can introduce irregular regions where the material aggregates in an unwanted manner, which can cause various problems when the DSC electrolyte should be distributed evenly throughout the layer. This is particularly significant for layers of metal hydride particles which to a large extent consist of non-regular (non-uniform) shaped particles.

Disclosure of Invention

It is an object of the present invention to provide a cost-effective method for the preparation of a dye-sensitized solar cell DSC having a porous conductive powder layer.

The porous conductive powder layer will have low electrical losses due to its low resistivity. The porosity of the porous conductive powder layer enables transport of ions and dyes through the layer.

A DSC containing a porous conductive powder layer will have increased current handling capability. This enables the construction of dye-sensitized solar cell modules, in which each cell can have a large area.

The porous conductive powder layer may have different functions in DSC:

-back contact function. The back contact extracts electrons from the working electrode.

-counter electrode function. The counter electrode transfers electrons to the electrolyte.

Both the back contact and the counter electrode may be porous conductive powder layers.

The porous conductive powder layer used as the back contact is in direct electrical contact with the working electrode.

The counter electrode comprises a second porous conductive powder layer. The second porous conductive powder layer can have catalytic particles integrated in the porous conductive powder structure. Alternatively, the second porous conductive layer comprises a porous conductive powder layer and a separate catalytic layer in direct contact with the porous conductive powder layer. A second porous conductive powder layer is formed in the same manner as the porous conductive powder layer.

The porous conductive powder layer is formed by the following method:

-depositing a deposit comprising metal hydride particles onto a substrate;

-heating the deposit in a subsequent heating step to decompose the metal hydride particles into metal particles; and sintering the metal particles for forming a porous conductive powder layer.

In the case where the second porous conductive layer is in contact with a separate catalytic layer, then the second porous conductive powder layer is formed by:

-depositing a deposit comprising metal hydride particles onto the catalytic layer or depositing the catalytic layer onto a deposit comprising metal hydride particles.

-heating the deposit in a subsequent heating step to decompose the metal hydride particles into metal particles; and sintering the metal particles for forming a porous conductive powder layer.

In order to minimize the cell resistance, it is advantageous to deposit the catalytic layer as close to the back contact layer as possible.

The metal hydride is brittle and the metal hydride particles have a non-spherical, irregular form. The deposit of metal hydride particles forms a relatively stable layer and compaction of this layer to achieve inter-particle contact and mechanical stability is not necessary. In a subsequent heating step or steps, the metal hydride particles are decomposed into metal particles and the metal particles are sintered to form a porous conductive powder layer. The decomposition of the metal hydride particles may occur in the same heat treatment step as sintering or in a separate step prior to the sintering heat treatment step. Sintering is preferably performed in a vacuum or inert gas to prevent contamination of the particles.

The heat treatment temperature sufficient for sintering between the particles to occur depends on the material used. The temperature is usually 550-1250 ℃, 550-850 ℃ or 700-1200 ℃.

The first heat treatment step below the sintering temperature and above the hydride decomposition temperature is typically performed at a temperature of 300-. For example, TiH can be preheated at 350-550 deg.C₂To release a significant amount of hydrogen prior to sintering.

The metal particles formed from the metal hydride particles attain a non-spherical, irregular form and may be substantially free of oxides on the surface. This makes the particles suitable for forming a porous conductive powder layer having excellent conductivity.

For printing deposits, various techniques known in the art can be used. Examples of printing techniques are slot die coating, gravure printing, screen printing, knife coating, doctor blade coating, doctor blading, flexography, dip coating or spray coating. The dry powder deposition may be performed, for example, by sieving or electrostatic powder deposition.

The metal hydride particles can be mixed with a liquid to form an ink suitable for a printing process. The particles may also be milled or otherwise treated to achieve one or more particular particle sizes for forming the porous conductive powder layer. Other components, also in solid form, may be added to the ink. The deposits for dry powder deposition may contain other components for facilitating the deposition process.

The deposit of metal hydride can be mixed with particles of pure metal or metal alloy.

The porosity of the porous conductive powder layer is important in order to ensure the passage of the electrolyte in the structure. If the electrolyte is not well distributed, the efficiency of the cell will be reduced.

The porosity of the porous conductive powder layer should preferably be 30-70%, or 45-65%, or 40-60%.

The metal hydride may be a pure metal hydride or a metal alloy hydride or a mixture thereof.

The resulting metal component forming the porous conductive powder layer must have suitable corrosion resistance to withstand the environment in the DSC.

The metal hydride is preferably a hydride of titanium or a titanium alloy or a mixture thereof. Other examples are hydrides of nickel alloys such as hastelloy, inconel, haynes cobalt chromium tungsten and monel, or hydrides of molybdenum, tungsten, chromium, zirconium, niobium or alloys thereof or mixtures thereof.

Depending on which metal is used for the porous conductive powder layer and which application method is used, the thickness of the layer may vary from about 1 micron to 100 microns or from 1 micron to 50 microns.

Deposition can be performed on various types of substrates. The substrate may be rigid or flexible and dense or porous.

Examples of substrates are TCO-less glass, TCO-coated glass, metal. Other examples of substrates are porous ceramic substrates. Examples of porous ceramic substrates are glass microfiber-based substrates, or aluminosilicate fiber-based substrates or substrates comprising aluminosilicate fibers and glass fibers.

Porous ceramic substrates have some advantages as substrates because they are chemically inert, can withstand high temperatures, and are readily available and inexpensive and simple to handle in various process steps. The porous substrate is an electrical insulator, but is permeable to liquid and electrolyte ions.

The porous substrate is flexible and can be processed in the form of a sheet or in the form of a roll for a continuous process.

The substrate with release function enables the formation of a separate porous conductive powder layer that can be integrated into the cell structure during the manufacture of the DSC. Examples of such substrates are, for example, graphite, zirconia, yttria, boron nitride or substrates provided with a thin release layer of, for example, zirconia, yttria, boron nitride, enabling the formation of a separate porous conductive powder layer.

Additionally, it is also possible to print a porous conductive powder layer onto the DSC component, such as the separator layer or the working electrode.

The porous conductive powder layer may be formed from a deposit comprising a catalyst, thus forming a second porous conductive powder layer. The second porous conductive powder layer is suitable as a counter electrode for DSC.

The porous conductive layer can also be in direct contact with the catalytic layer, thus forming a second porous conductive powder layer. The second porous conductive powder layer is suitable as a counter electrode for DSC.

Deposition onto the porous substrate may be performed by depositing deposits onto both sides of the porous substrate. The deposition on one side may form a porous conductive powder layer and the deposition on the other side may form a second porous conductive powder layer. Subsequent thermal treatment of the deposits may be performed after deposition onto both sides of the substrate has occurred.

The back contact and counter electrodes are formed by the porous conductive powder layer and the second porous conductive powder layer, respectively. In order to allow light to reach the working electrode, a transparent substrate is placed on the side of the incident light.

There are several advantages for a DSC according to the invention comprising a porous conductive powder layer and/or a second porous conductive powder layer:

the use of metal hydrides enables the porous conductive powder layer to be formed from relatively inexpensive materials;

the transformation of the metal hydride particles to metal particles having a non-spherical, irregular form gives a porous layer with a uniformly distributed porosity;

the metal particles are substantially free of oxygen and the porous layer resulting from sintering has good metal particle to particle connection and thus excellent electrical conductivity;

a porous conductive powder layer allows rapid electrolyte ion transport and rapid dye sensitization;

thicker porous conductive powder layers can be formed without electrolyte ion transport or dye sensitization problems;

a highly conductive porous conductive powder layer film can be formed which allows the printing of wider solar cell segments;

printing or dry powder deposition is much faster and cheaper than vacuum deposition techniques such as sputter deposition or electron beam evaporation deposition and can be performed selectively, so that the layers can be printed in a pattern without the need for expensive masking;

the method for forming the porous conductive powder layer is very flexible and a variety of substrates are available.

When using e.g. TiH₂The reason for the excellent conductivity when the particles replace Ti particles may be that the reducing atmosphere caused by the hydrogen gas released during the vacuum sintering process effectively removes any oxides from the surface of the titanium hydride particles.

Another possible explanation for good conductivity is that of TiH₂The non-spherical, irregularly shaped titanium particles formed by the base particles accept high particle-to-particle connectivity, which facilitates the sintering process, and thus enables the formation of both porous and irregular shaped titanium particlesA conductive powder layer.

The ease of printing or dry powder deposition of the deposit, the inexpensive materials used and the improved conductivity of the DSC comprising a porous conductive powder layer leads to cost-optimized dye-sensitized solar cells with improved performance characteristics.

Detailed Description

The invention is further explained with reference to the following description of exemplary embodiments and the accompanying drawings.

Mention of TiO₂The working electrode is not limited to TiO₂But may also be any other material or materials suitable for forming a dyed working electrode for a DSC, such as ZnO. Likewise, the dye may be any dye suitable for the working electrode and the electrolyte is any electrolyte or solid electrolyte suitable for DSC.

Examples with deposits containing titanium hydride are shown below. The titanium hydride can also be a titanium alloy hydride or a mixture of titanium hydride and titanium alloy hydride.

Other metal hydrides may also be used, such as hydrides of nickel alloys such as hastelloy, inconel, haynes cobalt chromium tungsten, and monel, or hydrides of molybdenum, tungsten, chromium, niobium, or alloys or mixtures thereof.

The deposit comprising metal hydride particles may be prepared in an ink suitable for printing. The ink may comprise, for example, an organic binder for improving print quality. The binder is removed prior to the sintering heating step.

The deposit can be placed in a reducing atmosphere, such as hydrogen or H₂Organic substances are removed in a heat treatment in an/Ar atmosphere.

For forming the second porous conductive powder layer, the deposit used to print the counter electrode may contain a catalyst. Or a solution containing the catalyst is separately printed onto a preformed porous conductive powder layer. The catalyst may be a catalytic amount of platinum or other known catalysts suitable for use in DSC. For example, a conductive carbon powder may be platinized and a surface layer of platinum formed on the carbon surface. Such platinized carbon powder may be added to the ink to form a deposit for the second porous conductive powder layer to impart catalytic properties thereto. Alternatively, a porous conductive powder layer is deposited on top of the catalytic layer. One example of a catalytic layer is a porous conductive powder layer of titanium containing platinized carbon particles.

It may be advantageous to first make the fibrous substrate surface smoother before deposition onto the porous substrate. This can be done in various ways, for example by mixing inert porous ceramics such as aluminosilicates, SiO2, Al₂O₃Or some other high temperature compatible ceramic (which is also chemically compatible with the DSC cell components) onto the surface of the porous substrate. The porous substrate may also be made smoother by applying pressure to the porous substrate and possibly also heat, for example by passing the porous substrate through a pressure roller.

DSCs may have different arrangements. Examples of arrangements of DSCs containing porous conductive powder layers are shown in fig. 1-3. These examples are not an exhaustive list of possible DSC arrangements.

FIG. 1-Cross section of a Sandwich-type DSC

FIG. 2-Cross section of a monolithic DSC

FIG. 3-Cross section of monolithic DSC

FIGS. 4a, b, c-SEM pictures of a layer of sintered metal particles

Figure 1 shows a cross-section of a sandwich-type DSC. Dyed TiO₂The working electrode layer 1 is located on top of the substrate 2. Porous conductive powder layer 3 on dyed TiO₂The upper part of the working electrode layer 1. A counter electrode 4 comprising a platinized porous conductive powder layer 5 and a substrate 6 is located opposite the working electrode 1. The electrolyte 7 permeates the porous conductive powder layer 3 and the working electrode 1 and the counter electrode 4.

Porous conductive powder layer 3 acting as dyed TiO₂Back contact of the working electrode layer 1. This means that the TCO back contact layer used in conventional DSCs can be omitted and replaced by a porous conductive powder layer. The porosity of the porous conductive powder layer 3 allows the electrolyte 7 to penetrate into and through the porous conductive powder layer. The dyed TiO can be extracted through the porous conductive powder layer₂The photo-induced charge generated in (c).

The counter electrode 4 with the second porous conductive powder layer containing the platinum catalyst is replacing the platinum coated TCO layer on glass, both in terms of conductivity and catalytic effect.

The second porous conductive powder layer in the DSC may function only as an electron conductor in the counter electrode, and in this case a separate catalytic layer must be included in the counter electrode and in direct contact with the porous conductive powder layer.

Dyed TiO₂The substrate 2 on the working electrode layer 1 should be a transparent substrate, such as glass.

Fig. 2 shows a cross section of a monolithic DSC. TiO exhibiting dyeing₂The working electrode layer 1 is on top of the substrate 2. TiO showing porous conductive powder layer 3 in dyeing₂The upper part of the working electrode layer 1. A porous separator 8 is deposited on top of the porous conductive powder layer 3. The second porous conductive powder layer containing the catalyst serves as a porous counter electrode 9 deposited on top of separator 8. The electrolyte (not shown in fig. 2) permeates the counter electrode 9, the separator 8, the porous conductive powder layer 3 and the dyed TiO₂A working electrode layer 1.

The porous conductive powder layer 3 serves as the back contact for the working electrode 1. This means that the TCO back contact layer used in conventional DSCs can be omitted and replaced by a porous conductive powder layer. The porosity of the porous conductive powder layer allows electrolyte to penetrate into and through the porous conductive powder layer. Extraction of dyed TiO by means of a porous conductive powder layer₂The photo-induced charge generated in (c). Since the porous conductive powder layer is conductive, the need for a TCO layer for charge extraction is eliminated.

Dyed TiO₂The substrate 2 below the working electrode layer 1 should be transparent, e.g. glass or plastic.

Separator 8 is a porous, chemically inert, and poorly conducting oxide such as alumina, aluminosilicate, magnesia, silica, and zirconia. The separator material should also be substantially inert to the electrolyte and dye sensitization process. The separator layer 8 should adhere well to the porous conductive powder layer 3 and provide sufficient electrical insulation as well as good porosity and electrolyte penetration with minimal resistance drop in the electrolyte. The separator layer may be formed by multiple depositions of chemically inert and poorly conductive layers of the same or different materials. The separator layer may also be formed by alternating layer deposition of chemically inert and poorly conductive layers.

The porous counter electrode 9 may have a catalytic layer and a conductive layer. The catalytic layer is adapted to catalyze a redox reaction at the counter electrode in the cell.

Fig. 3 shows a cross section of a monolithic DSC. A porous conductive powder layer containing platinum particles is deposited as a porous counter electrode 9 on top of the substrate 2, a separator 8 is deposited on top of the porous counter electrode 9, a porous conductive powder layer 3 is formed on top of the separator 8, and TiO₂The working electrode layer 1 is deposited on top of the porous conductive powder layer 3. The electrolyte (not shown in fig. 4) is in contact with the counter electrode 9, the separator 8, the porous conductive powder layer 3 and the dyed working electrode 1.

In fig. 3, the porous conductive powder layer 3 serves as the back contact for the working electrode 1. This means that the TCO back contact layer used in conventional DSCs can be omitted and replaced by a porous conductive powder layer.

The substrate 2 on the porous counter electrode 9 may be a glass substrate or a metal substrate.

To prepare the DCS shown in fig. 1-3, the cells are sealed and additionally electrically connected so that the photo-induced current can be used in an external circuit.

Fig. 4 shows an SEM photograph of a free-standing porous conductive powder layer of titanium particles formed from titanium hydride. The titanium hydride based ink was deposited on a zirconia substrate and dried. Vacuum sintering was carried out at 850 ℃ for 30 minutes. The release properties of zirconia after sintering make it possible to remove the porous conductive powder layer from the zirconia substrate and form a free-standing layer that can be processed without support. As shown in the figure, the shape of the titanium particles is irregular and non-spherical. The irregular shape of the resulting titanium particles in the porous conductive powder layer is typical for titanium hydride particle deposits.

Fig. 4b shows a separate porous conductive powder layer of titanium particles formed from titanium hydride particles. The titanium hydride ink was deposited on an alumina substrate previously deposited with a layer of boron nitride particles. Vacuum sintering was carried out at 850 ℃ for 30 minutes. As shown in the figure, the bulk of boron nitride particles is located on top of a porous conductive powder layer of titanium.

Fig. 4c shows a separate porous conductive powder layer of titanium particles formed from titanium hydride particles. The sintering temperature of the porous conductive powder layer was 850 ℃ for 30 minutes. As shown in the figure, porous TiO of the working electrode₂Layer (TiO of about 20 nm)₂Particle size) is deposited on top of the porous conductive powder layer. Deposited TiO₂The calcination temperature of (2) was 500 ℃ for 15 minutes.

The SEM micrographs of FIGS. 4a, b and c show the structure of sintered particles of a porous conductive powder layer having non-spherical and irregularly shaped titanium particles and particles made of TiH₂Sharp edges of titanium particles obtained from the base deposit.

Examples

Example 1-porous conductive powder layer on ceramic substrate

By mixing TiH₂Mixed with terpineol to prepare the ink. The ink was then bead milled using 0.3mm zirconia beads at 5000RPM for 25 minutes. Separation of zirconia beads from ink by filtration. The filtered ink was then printed onto a 38 micron thick glass microfiber substrate and then dried at 200 ℃ for 5 minutes. The coated glass microfiber substrate was then vacuum sintered at 585 ℃. The pressure during sintering was below 0.0001 mbar. The obtained porous conductive powder layer is a titanium metal porous film.

Additional DSC components were then printed onto the porous conductive powder layer and ceramic microfiber-based substrate.

A variant of example 1 is that the substrate is based on aluminosilicate fibres.

Another variation of example 1 is that the substrate comprises a mixture of aluminosilicate fibers and glass microfibers.

Another variation of example 1 is to pass the substrate through a heated rubber coated roller prior to printing, resulting in smoothing of the substrate surface.

Another variation of example 1 is to treat the substrate with colloidal silica before passing the substrate through a rubber coated roller.

Example 2 porous conductive powder layer printed on ceramic substrate

By mixing TiH₂Mixed with terpineol to prepare the ink. The ink was then bead milled using 0.3mm zirconia beads at 4000RPM for 30 minutes. The zirconia beads were separated from the ink by filtration. The filtered ink was then printed onto a 40 micron thick 90% porous ceramic substrate of aluminosilicate fibres and then dried at 200 ℃ for 5 minutes. The coated ceramic substrate was then vacuum sintered at 850 ℃ for 30 minutes and then cooled to about 20 ℃. The pressure during sintering was below 0.0001 mbar. The obtained porous conductorThe electric powder layer is a titanium metal porous membrane. Additional DSC components were then printed onto the porous conductive powder layer and ceramic substrate. The porous conductive powder layer had a thickness of 16 microns and a porosity of 44%. The sheet resistance was measured to be less than 0.5 Ohm/sq.

Example 2A variant is the printing of TiH₂The ink is first treated with porous TiO₂The ceramic substrate is layer printed to make the substrate surface smoother and flatter. We have found that in printing TiH₂The smoother the substrate surface before the ink, the lower the sheet resistance of the porous conductive powder layer for a given porous conductive powder layer thickness.

Example 3 second porous conductive powder layer with platinum deposited on ceramic substrate

By mixing TiH₂Mixed with terpineol to prepare the ink. The ink was then bead milled using 0.3mm zirconia beads at 5000RPM for 25 minutes. The zirconia beads were separated from the ink by filtration. The filtered ink was then mixed with hexachloroplatinic acid and printed onto a 33 micron thick porous ceramic substrate of aluminosilicate and then dried at 200 ℃ for 5 minutes. The printed ceramic substrate was then vacuum sintered at 585 ℃ and then cooled to room temperature. The pressure during sintering was below 0.0001 mbar. The resulting second porous conductive powder layer comprises a titanium metal porous membrane with a catalytic amount of platinum.

A variation of example 3 is that the filtered ink is not mixed with hexachloroplatinic acid, but the hexachloroplatinic acid solution is printed onto a vacuum sintered porous conductive powder layer, which is then dried, followed by heating to decompose the deposited hexachloroplatinic acid to deposit platinum on the surface, thus forming a second porous conductive powder layer.

Another variation of example 3 is that the filtered ink is not mixed with hexachloroplatinic acid, but the filtered ink is mixed with platinized conductive particles.

A variant of example 3 is that, instead of aluminosilicate fibres, the substrate is based on glass microfibres.

Another variant of example 3 is that the substrate is based on aluminosilicate fibres and glass microfibres.

The substrate may be passed through a heated rubber coated roller prior to printing, resulting in smoothing of the substrate surface.

Example 4-second porous conductive powder layer with platinum deposited on ceramic substrate

By mixing TiH₂Mixed with terpineol to prepare the ink. The ink was then bead milled using 0.6mm zirconia beads at 6000RPM for 25 minutes. The zirconia beads were separated from the ink by filtration. The filtered ink was then mixed with hexachloroplatinic acid and printed onto a 32 micron thick 90% porous ceramic substrate of aluminosilicate and then dried at 200 ℃ for 5 minutes. The printed substrate was then heat treated and sintered in vacuum at 850 ℃ for 30 minutes, and then first cooled to about 100 ℃. The pressure during sintering was below 0.0001 mbar. The resulting second porous conductive powder layer comprises a titanium metal porous membrane with a catalytic amount of platinum. The second porous conductive powder layer had a thickness of 20 microns and a porosity of 50%. The sheet resistance is less than 0.6 Ohm/sq.

A variation of example 4 is that the filtered ink is not mixed with hexachloroplatinic acid, but rather a hexachloroplatinic acid solution is printed onto a vacuum sintered porous conductive powder layer and then dried and heated to decompose the deposited hexachloroplatinic acid to deposit platinum on the surface of the second porous conductive powder layer.

Can print TiH₂The ink is preceded by first printing the ceramic substrate with a porous aluminosilicate layer to make the substrate surface smoother and more planar.

Example 5-porous conductive powder layer on ceramic substrate printed to both sides

By mixing TiH₂Mixed with terpineol to prepare the ink. The ink was then bead milled using 0.3mm zirconia beads at 5000RPM for 25 minutes. The zirconia beads were separated from the ink by filtration. The filtered ink was then mixed with platinized conductive particles and printed onto a 33 micron thick porous glass microfiber substrate, and then dried at 200 ℃ for 5 minutes.

Will subsequently be formed by mixing TiH₂Another ink, prepared with terpineol and bead milled and filtered, was printed onto the opposite side of the glass microfiber substrate such that the first and second printed layers were separated by the glass microfiber substrate. The two-sided printed substrate was then dried at 200 ℃ for 5 minutes.

The two-side coated ceramic substrate was then vacuum sintered at 585 deg.c and allowed to cool to room temperature. The pressure during sintering was below 0.0001 mbar. The resulting two-sided printed substrate has a porous conductive powder layer of titanium metal on one side and a second porous conductive powder layer containing titanium metal with a catalytic amount of platinum on the other side.

A variation of example 5 is to deposit a porous ceramic coating on the opposite side of the ceramic substrate before printing the second porous conductive powder layer. Such ceramic printing may be useful in order to prevent electrical contact between the first and second porous conductive powder layers.

Another variant of example 5 is the application to TiH before preparing the ink, for example by deposition₂Thermal decomposition of platinum salts on powders TiH surface treated with platinum₂And (3) powder.

Another variation of example 5 is to mix the filtered ink with hexachloroplatinic acid instead of with platinized conductive particles.

Example 6-porous conductive powder layer on double-sided printed ceramic substrate

By mixing TiH₂Mixed with terpineol to prepare the ink. The ink was then bead milled using 0.3mm zirconia beads at 5000RPM for 40 minutes. The zirconia beads were separated from the ink by filtration. The filtered ink was then mixed with hexachloroplatinic acid and printed onto a 20 micron thick porous ceramic substrate of aluminosilicate 60%, and then dried at 200 ℃ for 5 minutes.

Then another one containing TiH₂The ink of (a) was printed on the other side of the ceramic substrate and then dried at 200 c for 5 minutes.

The two-sided printed ceramic substrate was then vacuum sintered at 850 ℃ for 30 minutes and then allowed to cool. The pressure during sintering was below 0.001 mbar. The resulting two-sided printed substrate has a first porous conductive powder layer on one side comprising a porous film of titanium metal and a second porous conductive powder layer on the other side comprising titanium metal with a catalytic amount of platinum on porous (on-porous). The sheet resistance of each porous conductive powder layer is less than 0.3 Ohm/sq. Each layer has a thickness of about 10 microns. The porosity of each layer is higher than 45%.

A variation of example 6 is to print the porous ceramic on the opposite side of the ceramic substrate before printing the second porous conductive powder layer. Such ceramic printing may be useful in order to prevent electrical contact between the first and second porous conductive powder layers, and thus may be useful in preventing electrical shorting between the first and second porous conductive powder layers.

Example 6 Another variant is the printing of TiH₂The ceramic substrate was printed with porous ceramic on both sides before the ink.

Another variant of example 6 is the application to TiH before preparing the ink, for example by deposition₂Thermal decomposition of platinum salts on particles TiH surface treated with platinum₂And (3) granules.

Example 7 DSC based on porous conductive powder layer printed on both sides onto ceramic substrate

20 micron thick TiO containing 20nm particles₂The ink layer was screen printed onto the platinum-free first porous conductive powder layer side of a two-sided printed glass microfiber substrate prepared according to example 5 or 6. Dried TiO₂The thickness of the ink layer is 1-2 microns. Second 60 micron thick TiO₂The ink layer is printed on the first TiO₂On top of the layer and dried. Adding a third TiO₂The layer is printed on the second TiO₂On top of the layer and dried. Followed by deposition of TiO in air at 500 deg.C₂The structure of (2) was subjected to a heat treatment for 20 minutes. After cooling to about 70 ℃, the TiO will be deposited₂The structure of (1) was immersed in a 20mM solution of Z907 dye in methoxypropanol and heat treated at 70 ℃ for 30 minutes followed by rinsing in methoxypropanol. An electrolyte is then added to the porous conductive powder layer double side printed ceramic substrate and the structure is sealed.

Example 8 deposition onto TiO₂Porous conductive powder layer on working electrode

Adding TiO into the mixture₂The ink layer was printed on top of a borosilicate glass substrate and then dried at 120 c for 15 minutes. Dried TiO₂The thickness of the ink layer isAbout 6 microns. Adding a second TiO₂The ink layer is printed on the first TiO₂On top of the layer and dried. Dried second TiO₂The ink layer had a thickness of about 6 microns. Followed by deposition of TiO in air at 500 deg.C₂The glass of (2) is subjected to a heat treatment for 15 minutes.

Will be prepared by mixing TiH₂Printing of inks prepared with terpineol and bead milling and filtration onto deposited TiO₂On the layer, it was then dried at 200 ℃ for 5 minutes. Followed by heating the coated TiH in vacuo at 500 deg.C₂Of TiO 2₂Glass substrate 10 minutes. The substrate was then vacuum sintered at 1000 c for 30 seconds and then allowed to cool to about 20 c. The pressure during sintering was below 0.001 mbar. Subsequently, a coating layer is deposited on the surface of the substrate₂The structure of the porous conductive powder layer on glass of (a) is ready for further preparation into a DSC.

Example 9 independent porous conductive powder layer

By mixing 8 parts by weight of TiH₂(particle size 9 μm) and 2 parts by weight of titanium particles (particle size: 1 μm) were mixed with terpineol to prepare an ink. The ink was then bead milled using 0.3mm zirconia beads at 6000RPM for 15 minutes and further bead milled at 7000RPM for 5 minutes to mix the titanium particles with TiH₂And forming TiH of suitable size₂And (3) granules. The zirconia beads were then separated from the ink by filtration. The filtered ink was then printed onto a ceramic substrate of zirconia and then dried at 200 ℃ for 5 minutes. Thereafter vacuum sintering the sintered material at 850 ℃ with TiH₂And a dried layer of titanium for 30 minutes, then cooled to about 20 ℃. The pressure during sintering was below 0.0001 mbar. The resulting porous conductive powder layer comprises a titanium metal porous film. The sintered porous conductive powder layer was removed from the zirconia substrate and prepared for integration in a DSC. Sheet resistance less than 0.9Ohm/sq and thickness 24 microns and porosity 51%.

EXAMPLE 10 independent porous conductive powder layer

An ink was prepared by mixing nickel alloy hydride particles (particle size 15 μm) with terpineol and milling the ink using 0.3mm zirconia beads at 6000RPM glass beads for 10 minutes. The zirconia beads were then separated from the ink by filtration. The filtered ink was then printed onto a ceramic substrate of zirconia and then dried at 200 ℃ for 5 minutes. The printed zirconia substrate with the dried layer of nickel hydride particles was then vacuum sintered at 750 ℃ for 30 minutes and then cooled to about 20 ℃. The pressure during sintering was below 0.0001 mbar. The resulting porous conductive powder layer contains a porous film of a nickel alloy. The sintered layer was removed from the zirconia substrate and was ready for integration in the DSC. The sheet resistance was less than 1Ohm/sq and the thickness was 19 microns with a porosity of 58%.

Example 11 independent porous conductive powder layer with platinum

By mixing TiH₂(particle size 8 μm) was mixed with terpineol to prepare an ink. The ink was bead milled using 0.3mm zirconia beads at 5000RPM for 25 minutes. The zirconia beads were separated from the ink by filtration. The filtered ink was mixed with platinized conductive particles and printed onto a zirconia ceramic substrate and then dried at 200 ℃ for 5 minutes. The printed zirconia substrate was thereafter vacuum sintered at 850 ℃ for 30 minutes and then cooled to about 25 ℃. The pressure during sintering was below 0.0001 mbar. The resulting second porous conductive powder layer comprises a titanium metal porous membrane with a catalytic amount of platinum. The sintered layer was removed from the zirconia substrate and prepared for integration as a counter electrode in the DSC.

EXAMPLE 12 independent porous conductive powder layer

By mixing TiH₂(particle size 8 μm) was mixed with terpineol to prepare an ink. The ink was bead milled using 0.3mm zirconia beads at 6000RPM15 minutes then bead mill the ink at 7000RPM to form a TiH of appropriate size for 5 minutes₂And (3) granules. The zirconia beads were separated from the ink by filtration. The filtered ink was printed onto a ceramic substrate of zirconia and then dried at 200 ℃ for 5 minutes. Thereafter vacuum sintering with dried TiH at 600 deg.C₂The printed zirconia substrate of the layer was then cooled to about 20 ℃. The pressure during sintering was below 0.0001 mbar. The resulting layer is a porous conductive powder layer of titanium. The sintered layer was removed from the zirconia substrate and was ready for integration in the DSC. The sheet resistance of the layer was measured to be less than 0.2 Ohm/sq. The porous conductive powder layer had a thickness of 12 microns and a porosity of 45%.

A variation of embodiment 12 may be to replace the zirconia substrate with a metal foil substrate such as a molybdenum foil pre-deposited with a thin layer of a non-stick material such as boron nitride or zirconia or yttria.

Example 13 independent porous conductive powder layer with platinum

By mixing TiH₂(particle size 8 μm) was mixed with terpineol to prepare an ink. The ink was bead milled using 0.6mm zirconia beads at 6000RPM for 15 minutes. The zirconia beads were then separated from the ink by filtration. The filtered ink was mixed with hexachloroplatinic acid and printed onto a ceramic substrate of zirconia, and then dried at 200 ℃ for 5 minutes. The printed zirconia substrate was then vacuum sintered at 900 ℃ for 25 minutes and then cooled to about 20 ℃. The pressure during sintering was below 0.0001 mbar. The resulting layer is a porous conductive powder layer of titanium with catalytic amounts of platinum. The sintered layer was removed from the zirconia substrate and prepared for integration as a counter electrode in the DSC. The sheet resistance of this layer is less than 0.3 Ohm/sq. The layer had a thickness of 10 microns and a porosity of 48%.

A variation of example 13 is that the filtered ink is not mixed with hexachloroplatinic acid, but rather a hexachloroplatinic acid solution is printed onto the vacuum sintered porous conductive powder layer and then dried and heated to decompose the deposited hexachloroplatinic acid to deposit platinum on the surface of the vacuum sintered porous conductive powder layer.

Example 14 DSC based on a separate porous conductive powder layer

The porous conductive powder layer prepared according to example 12 was impregnated with 0.02M TiCl₄In aqueous solution and heat treated at 70 ℃ for 30 minutes. From TiCl₄The solution removed the layer and was washed first with water and then with ethanol. Followed by the addition of TiO₂The base ink layer is printed on one side of the PCPL and then dried. Dried TiO₂The thickness of the ink layer is 1-2 microns. Second 60 micron thick TiO₂The ink layer is printed on the first TiO₂On top of the layer and dried. Adding a third TiO₂The layer is printed on the second TiO₂On top of the layer and dried. The structure was then subjected to a heat treatment at 500 ℃ in air for 30 minutes. After allowing the structure to cool, the structure was immersed in 0.02M TiCl₄In aqueous solution and heat treated at 70 ℃ for 30 minutes. Rinsing the deposited TiO in water and ethanol₂After the PCPL, it was heat-treated at 500 ℃ for 5 minutes in air. Followed by deposition of TiO₂The porous conductive powder layer structure of (a) was immersed in a 20mM solution of Z907 dye in methoxypropanol and heat treated at 70 ℃ for 30 minutes, then rinsed in methoxypropanol. Separate second porous conductive powder layer comprising platinum or PCPL having platinum deposited on a ceramic substrate located off-and-dyed TiO according to examples 11 or 13₂The working electrode layer is at 25 microns on the underside of the porous powder layer opposite. After which electrolyte is added and the cell is sealed. The efficiency of the cell was measured under simulated AM1.5 light. The efficiency of the cell was 8.2%.

Example 14A variant in which one or both TiCl's are omitted₄And (6) processing.

Another variation of example 14 is to replace the separate second porous conductive powder layer with a platinum-plated titanium foil.

Another variation of example 14 is to use the second porous conductive powder layer with platinum deposited on a ceramic substrate according to example 3 or 4 as a counter electrode instead of using a separate second porous conductive powder layer with platinum. To avoid short circuits, the surface of the ceramic substrate opposite the second porous conductive powder layer was brought into contact with the dyed TiO₂The layers are opposite the underside of the porous conductive powder layer.

EXAMPLE 15 porous conductive powder layer on ceramic substrate deposited using Dry powder

By depositing TiH using dry powder techniques₂Sieving the powder onto a ceramic substrate to size the particles<2 micron TiH₂The powder is deposited onto a zirconia ceramic substrate. The deposited ceramic substrate was then vacuum sintered at 850 ℃ for 30 minutes and then allowed to cool to about 20 ℃. The pressure during sintering was below 0.0001 mbar. Thereafter, the vacuum sintered porous conductive powder layer was removed from the zirconia substrate and prepared for integration into a DSC. The sheet resistance of this layer is less than 0.7 Ohm/sq. The layer had a thickness of 32 microns and a porosity of 56%.

Example 16-porous conductive powder layer on two-sided printed ceramic substrate, where the second porous conductive powder layer has a separate catalytic layer

By mixing TiH₂Mixed with terpineol to prepare the ink. The ink was then bead milled using 0.3mm zirconia beads at 5000RPM for 25 minutes. The zirconia beads were separated from the ink by filtration. The filtered ink was then mixed with platinized conductive particles and printed onto 33 micron thick porous glass microfibersThe substrate was dried at 200 ℃ for 5 minutes.

By mixing TiH₂Mixed with terpineol to prepare another ink. The ink was then bead milled and filtered, followed by printing a second layer containing no platinum onto the first printed layer containing platinized conductive particles. The printed substrate was then dried at 200 ℃ for 5 minutes.

By mixing TiH₂Mixed with terpineol to prepare an ink. The ink was then bead milled and filtered, and then a third layer was printed onto the opposite side of the glass microfiber substrate such that the first printed layer was separated from the second and third printed layers by the glass microfiber substrate. The two-sided printed substrate was then dried at 200 ℃ for 5 minutes.

The two-sided printed ceramic substrate was then vacuum sintered at 585 deg.c and then allowed to cool to room temperature. The pressure during sintering was below 0.0001 mbar. The resulting two-sided printed substrate has a porous conductive powder layer of titanium metal on one side of the glass microfiber substrate, and a second porous conductive powder layer comprising titanium metal and platinum and a third porous conductive powder layer comprising titanium metal are present on the other side of the glass microfiber substrate.

In embodiments, the ink may be made using water as the solvent, or organic solvents such as terpenoids, alcohols, glycol ethers, glycol ether acetates, ketones, hydrocarbons, and aromatic solvents may also be used.

A binder or other such substance may be used to enhance the mechanical strength of the deposited particulate layer prior to heat treatment of the layer.

To achieve a catalytic effect in the counter electrode, metal hydride particles such as platinum-coated ITO, ATO, PTO, and FTO may be mixed in the platinum-coated particles of the conductive metal oxide. Platinized particles of conductive metal carbides and metal nitrides may also be mixed with the metal hydride particles. Particles of platinum-coated carbon black or graphite may also be mixed with the metal hydride particles. Platinization can be accomplished by mixing, for example, a dissolved platinum salt, such as hexachloroplatinate or platinum tetrachloride, with the conductive particles and removing the solvent by evaporation and heating the mixture to a temperature high enough to decompose the platinum salt and deposit metallic platinum onto the surface of the conductive particles.

There are many variations possible for making porous conductive powder layers and DSCs comprising porous conductive powder layers according to the present invention, and the examples represent only a few of the possible variations.

Claims (16)

1. A method for manufacturing a dye-sensitized solar cell with a double-sided printed substrate, comprising a porous conductive powder layer back contact and a counter electrode, characterized in that:

-printing a deposit comprising metal hydride particles onto one side of a porous ceramic substrate to form a porous conductive powder layer as a back contact; and

-printing a deposit comprising metal hydride particles onto the other side of the porous ceramic substrate to form a second porous conductive powder layer as a counter electrode;

-heating the deposit in one or more subsequent heating steps to decompose the metal hydride particles into metal particles; and sintering the metal particles for forming a porous conductive powder layer.

2. The method according to claim 1, characterized in that the first subsequent heating step is carried out at a temperature of 350-500 ℃, which is above the hydride decomposition temperature and below the sintering temperature of the metal particles, and the second subsequent heating step is carried out at a temperature at which the metal particles are sintered.

3. The method according to claim 1, characterized in that the decomposition of the metal hydride and the sintering of the metal particles are carried out in a subsequent heat treatment step at a temperature at which the metal particles sinter.

4. The method as claimed in claim 1, wherein the sintering temperature of the metal particles is 550-1250 ℃.

5. The method of claim 1, wherein the sintering of the metal particles occurs in a vacuum or an inert gas.

6. The method according to claim 1, characterized in that the metal in the metal hydride particles is a metal selected from the group consisting of titanium, or a titanium alloy, or a nickel alloy, or molybdenum, or a molybdenum alloy, or tungsten, or a tungsten alloy, or chromium, or a chromium alloy, or niobium or a niobium alloy.

7. The method of claim 1, wherein the porous conductive powder layer comprises sintered metal particles having a non-spherical, irregular form.

8. The method according to claim 1, characterized in that the substrate is a porous ceramic substrate selected from a glass fiber substrate or an aluminosilicate fiber substrate or a substrate comprising aluminosilicate fibers and glass fibers.

9. The method according to claim 8, characterized in that the surface of the porous ceramic substrate is smoothed before the deposition of the deposit.

10. The method according to claim 1, characterized in that the porous conductive powder layer has a sheet resistance <1 ohm/sq.

11. The method of claim 1, wherein the printing is screen printing.

12. The method of claim 1, wherein the printing of the deposit comprising metal hydride particles onto the other side of the porous ceramic substrate to form a second porous conductive powder layer as a counter electrode comprises a catalyst for forming the second porous conductive powder layer.

13. A dye-sensitized solar cell, characterized in that it comprises a porous conductive powder layer back contact fabricated on one side of a porous substrate and a porous conductive powder layer counter electrode fabricated on the other side of the porous substrate, and that the back contact and counter electrode comprise sintered metal particles having a non-spherical, irregular form.

14. The dye-sensitized solar cell according to claim 13, comprising a porous conductive powder layer, characterized in that the counter electrode comprises integrated catalytic particles or a separate catalytic layer in direct contact with the counter electrode.

15. Dye-sensitized solar cell according to claim 13 or 14, characterized in that the back contact porous conductive powder layer has a sheet resistance <1 ohm/sq.

16. The dye-sensitized solar cell according to claim 13 or 14, characterized in that the working electrode comprises TiO₂And the back contact and counter electrode comprise titanium particles.