Substrate for an optoelectronic device

p0001A substrate for an optoelectronic device

p0002The present invention relates to a substrate for an opto-electronic device according to the preamble of claim 1.

p0003Numerous ways are known from the prior art known to a carrier layer (substrate) for an optoelectronic device, such as a solar cell, realizing. It is initially known and widely used to provide solar cells with the so-called first-generation silicon substrates.

p0004In recent times, these products increase efficiency, both in terms of electrical efficiency, as well as the (mass) Fertigbar- ability to simultaneously remain the inherent costs, including the cost of materials of silicon, too high to such a solar cell to enable further dissemination.

p0005So-called second-generation solar cells do not require more silicon. Here is by using various deposition technologies, such as plasma sputtering, or CVD, reached on a transparent substrate, typically a glass plate or a flexible polyamide a cost advantage by the cheaper substrates, however, still seem substrate costs even with this second generation (and i.Ü. also their flexibility in use) in need of improvement.

p0006There are therefore efforts (as significant cost drivers) further lower with so-called photovoltaic technologies of the third generation, the substrate costs, while still acceptable efficiencies (typically about 10%) are to be realized. Key technologies to achieve these goals put one hand expensive substrates (eg, films or meshes) for the active components requires the other hand, manufacturing processes at low temperature and ambient pressure (such as digital or screen) and high throughput in production. It is expected that in particular organic solar cells, tandem cells or so-called DSC solar cells (dye sensitized nano-structured solar cells) have the potential to achieve the goals.

p0007Furthermore, while semiconductor-based substrates are dominant with the aforementioned silicon-based solar cells of the first generation still prove to increasingly non-semiconductor-based substrates as powerful and technological alternatives: So proves about the ability of some non-Si photovoltaic materials at low light incidence angles or to produce low light intensity or even in polarized light sources current (there is also a wider spectrum of light used), to be advantageous over silicon; equally the advantages of flexible substrates (eg on film or fabric base) perceived when solar cells need to be rolled or folded, or other free formabilities for various application environments are required. At the same time, however, there is still a lack of a low-cost, high-performance and particularly simple and reliable to be produced in large series substrate material for optoelectronic devices such as solar cells.

p0008Object of the present invention is therefore a generic substrate for an optoelectronic device, in particular a photovoltaic or solar cell (or OLED) to create, which in improved optical properties, in particular transmission characteristics for interacting active layers, a simplified, particularly suitable for mass production, manufacturability allows at low material and manufacturing costs and high reproducibility.

p0009The object is solved by the substrate with the features of the main claim; Advantageous developments of the invention are described in the dependent claims. According to the invention protection is also claimed for any combination of at least two process characteristics which are evident from the present application documents; these are as belonging to the invention claimed. First, the fibers used for the production of the fabric (fibers) are arranged or chosen according to the invention advantageous that they see 30 .mu.m and 80 .mu.m with a fiber diameter of between 20 .mu.m and 100 .mu.m, in particular between, have - typically, the fibers for a particular implementation, a constant diameter. Additionally advantageous within the scope of the invention, the fabric is configured such that the mesh openings formed between the woven fibers realize an open area between approximately 70% and approximately 85%; This means that remaining one 15% to 30%, based on a total area of ​​the fibers to be taken.

p0010Further advantageous according to the tissue is at least one side hen with a transparent coating in the form of a (eg partially) filling verse-, which is implemented by an electrically non-conductive polymer.

p0011In this way, according to the invention advantageously realized that the substrate on a first side (uncoated surface side) is electrically conductive, since conductive fibers and / or an electrically conductive coating of the fabric of the transparent polymer coating is uninfluenced, while the other end ( on the second coated surface side) the transparent polymer material for electrical isolation provides.

p0012The polymer material can be further provided with ORMOCER® or SiOx or other inorganic material, in particular coated.

p0013Advantageously enables the optionally coated in polymer material and the thus formed transparent, electrically non-conductive coating is a moisture and / or UV-resistance (for example, by suitable incorporation of a UV absorber) of the substrate (and hence a built up thereon opto-electronic device), in addition, this coating material has an advantageous and further education according to the oxidation barrier. - A -

p0014With a coating thickness which is less established as a fabric thickness, typically about 70% to 85% of the fabric thickness and the fabric at least partially penetrates, can be so compact, visually and physically powerful, at the same time be manufactured easily and at a low cost substrate assembly realize.

p0015According to a preferred embodiment of the invention is a material for the polymer material is selected which an acrylic resin, a silicone material, an FIU can be oropolymer, or a polymer selected from the group consisting of PU, PEN, PI, PET, PA, EVA or comparable materials, more preferably thermal- or radiation-curing, with in particular a UV has been found radiation-curing lacquer to be particularly preferable.

p0016In view of the inventive fibers (fibers), it is first of all covered by the invention to produce the fabric consists essentially of non-electrically conductive fibers, which are then provided for the realization of the electrodes having an electric conductivity effect. Suitable fibers (fibers) are particularly semitransparent Monofilaments of PA, PP, PET, PEEK, PI, PPS, or the like fibers.

p0017For the manufacture of electrical conductivity, whereby preferably the fabric used for the substrate of the invention has a surface resistance <50Ω / sq, preferably <20Ω / sq, more preferably less than 10Ω / sq, comprises one hand it is encompassed by the invention, a further development according provide fibers in the fabric which are made of metal (metal fibers), or carry as fibers metallization. Suitable metals for realizing the metal fibers are as Ti, Ag, Al, Cu, Au, Pa, Pt, Ni, W, Mo, Nb, Ba₁ . Sn, Zr or the like, wherein the conductivity of the tissue (or surface resistivity) can be appropriately set by the geometry with which such a metallic or metallized thread is interwoven with non-conductive threads: In the context of suitable embodiments of the invention is it to be, such conductive filaments in the form of a binding 1: 1, or preferably 1: 2, 1: 3 or higher provide, additionally or alternatively by selecting the direction (weft, Chain), in which even a metallic or metal-coated fiber to be woven to make the conductivity adjustment (provided especially weaving in both directions shot, chain).

p0018Secondly, it is in the context of preferred realization of the invention possible and intended to establish the electrical conductivity and the desired low-resistance surface resistance by a metallization of the fabric, which even then is typically exclusively of non-conductive polymer fibers (which principally metallic fibers can be woven here) , Such metallic coating of the fabric may be suitable by plasma sputtering carried out (eg with Ag₁ Au, Ti, Mo, Cr, Cu, ITO, or the like ZAO.), Or alternatively by vapor deposition (Al, Ag, Cu, etc.) or, by wet chemical methods such as electrolysis, such as deposition of Ag, Ni Typically causes such metalization the fabric a particularly high conductivity, which <10Ω / sq reflected in a sheet resistance.

p0019As already explained above, a particular advantage of the invention in the high light transmittance or transmission of the invention unrealized substrate. This can be particularly beneficial influence by setting the inventively decorated mesh openings, in particular known methods for the production of precision fabrics can be applied low here. For realizing the inventively provided mesh sizes in accordance with the invention the open area between 70% and 85%, it has been found particularly preferable to adjust mesh sizes in the range between 200 .mu.m and 300 .mu.m, or the surface of a respective mesh size (preferably constant over the surface) to a range between about δO.OOOμm² and about 800,000 microns² set.

p0020According to the invention advantageously also usually is the total transmission (in%) of a substrate according to the invention is higher than the open area of ​​the fabric; added to the so-called direct transmission, namely passage of light through the mesh and through transparent fibers, comes a diffusive transmittance, which (for example in metal-coated fibers), a reflection at the fiber or the fiber taken into account, as a result, at a region of the present invention the open area between 70% and 85% of an actual total transmission between 75% and 95% is achievable.

p0021The present invention thus allows in potentially simple, elegant and inexpensive manner the production of optoelectronic devices for a variety of applications: While the photovoltaic likely prove annual general use in the present invention, in particular organic solar cells, thin film cells, DSC cells or tandem cells can be applied in the manner according to the invention to the substrate, it is nevertheless low and scope of the invention to realize other optoelectronic devices with the substrate. These include organic LEDs, other display technologies, various passive electronic components or large-area components, such as the like as for architectural applications. be used.

p0022Thus, it is expected that the present invention not only numerous advantages as compared to the known TCO electrodes (transparent Conduc- tive oxides, used as a transparent electrode) implemented, such as significantly lower manufacturing and material costs, non-requirement of a special vacuum-pressure system ( TCO must be done in a high vacuum), simpler technology with increased conductivity and reduced brittleness and improved substrate adhesion, also expected in the first place by means of the present invention provided the substrate for the possibility for large-area, flexible surfaces as optoelectronic devices, particularly in the context of photovoltaic (also for the production of OLEDs) to design.

p0023Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and with reference to the drawings; these show in 1 shows a substrate according to a first preferred embodiment of the invention in side sectional view.

p00242 shows an alternative realization form of a substrate according to a second preferred embodiment.

p0025Fig. 3 is a schematic sectional view of an organic solar cell, achieved by means of the substrate of the first embodiment according to Fig. 1; and

p0026FIG. 4 shows a further embodiment of the present invention in which the coating is introduced into the tissue so that both sides of an electrically conductive layer can be achieved and such a tandem solar cell can be constructed about.

p0027Fig. 1 shows the lateral schematic sectional view of a web of transparent PA-10 fibers having a thickness in the range between 30 microns and 35μm. Each second fiber in the weft (alternatively, also in the chain) is an AI-metallic filament 12 of a comparable yarn thickness in the range between about 30 microns and 35μm.

p0028This fabric is coated with a coating 14 of a transparent polymer (here: UV-curing acrylic resin) is provided such that one end (in Figure 1 below.) The coating 14, which with about 60 microns 75% to 85% of the layer thickness of the gE WEBES 10, 12 achieved an insulating layer forms, while at the top of the at least partially exposed metal fibers 12, the arrangement is electrically conductive and can act as an electrode. The coating 14 is applied so that it partially penetrates the fabric, ie, the effective thickness of the coating overlaps with a layer thickness of the fabric. In the shown binding 1: 1 (ie, each second thread in one direction is metallic) is a typical surface resistivity of 5Ω / sq feasible Alternatively, this surface resistance further reduced by the binding of 1: 2 or 1: 3, ie the ratio between the metallic thread 12 and non-metallic (non-conductive) fiber 10 is adjusted accordingly.

p0029Process technology, it is provided, the coating (eg acrylic resin) into a liquid state into the fabric, so that about the impregnation or partial penetration according to FIG. 1 is produced. This can for example happen that a thin layer of liquid resin, the fabric is applied and then a following crosslinking of the resin. Alternatively, possible and encompassed by the invention would be a procedure in which the coating in the form of a film or the like. solid state is present and then through a pressure, thermal or pressing process (eg by lamination ren) into contact with the tissue is brought, that the arrangement shown in FIG. 1 is produced.

p0030In such an arrangement, an optoelectronic device can be applied, such as in connection with Fig. 3 (here, the substrate of FIG. 1 is at the top, wherein, the reverse of the illustration in FIG. 1, provided with the coating 10, closed outer surface pointing upwards). Arrows 16 illustrate the light incident on the transparent layer 4; by their polymeric material and the transparent fibers 10 (or intermediate mesh) penetrates the light in an underlying, in contact with the conductive fibers 12 a coated active layer 18th This active layer is for example realized by PEDOT + P3HT: PCBM / C60 (for organic solar cells) or by TiO2 / dye / electrolyte (for DSC) and is closed on the opposite side of a counter electrode 20th In principle can be realized by the substrate of the invention also this counter electrode.

p0031With an example furnished by a suitable choice of the mesh open area of ​​about 80% and an achievable thereby transmissivity for the light 16 of about 90% can be as a organische- or DSC solar cell implemented, comprising not only favorable electrical properties, but with minimized material costs and simplified processes high enables cost savings over known solar cells and drastic efficiency potential.

p0032FIG. 2 illustrates a comparison with FIG 1 varied embodiment of the substrate according to a second embodiment of the present invention. Here is a realized from monofilaments tissue (PA₁ Fiber thickness was 30 microns to 35μm) were prepared only as a fabric and coated with metal after weaving, for example, by plasma sputtering of Ag on the tissue. Accordingly, Figure 2 shows the sectional view of Fig., A tissue-fiber assembly 30, which carries a thin layer of Ag (0.5 .mu.m), optionally additionally stabilized by means of a thin Ti coating.

p0033This assembly is then, similarly to the procedure in the embodiment of FIG. 1, fitted with a non-conductive transparent polymer, so that again one is (in the figure lower) side is completely closed and thus non-conductive, while, by appropriate selection the coating thickness, an upper portion of the conductive coating by fibers protrude. Again, can the to a value <10Ω / sq realizable surface resistance or the like by other means of coating. Adjust and provides analogous to proceeding further, as shown in FIG. 3 the possibility of a solar cell, an organic LED or the like. build optoelectronic device on it.

p0034The present invention is not limited to the embodiments or the above-described formulations or be selected material groups shown; rather it is in the appropriate dimensions, depending on a desired application, a suitable mate ha I strength to combine flexibility and resilience of the substrate material with the desired electrical conductivity properties, in the manner and within the scope of the invention, the materials, thicknesses, can mesh sizes of the fibers used is selected or varied accordingly, as well as to realize the electrodes effect the option of either conductive (metallic or metallized) fibers in a suitable weave ratio and / or adapted to be metallized a tissue in the manner described.

p0035In principle, it is also envisaged in the context of the invention are possible and the transparent, electrically non-conductive coating of the invention provided so that these are not about one-sided arranged an electrically non-conductive surface, but is provided in the substrate in the core portion thereof so that both sides of the Kerns each protruding fibers or fiber portions of the polymer and thus can form a conductive layer on both sides of the substrate, see for example the presentation in Fig. 4. such a configuration lend themselves to it, as then both sides of the substrate dual solar cells (tandem) build.

p0036As a result, the substrate offered by the present invention provides the ability to drastic improvements in efficiency in material use and production, is to be expected that that the photovoltaic or OLED technology (but also other optoelectronic applications) numerous new fields of application can be opened up.