ROOM TEMPERATURE METHOD FOR PRODUCING A PV LAYER SEQUENCE

Description

TECHNICAL AREA

[0001] The present invention can be generally applied to the field of electrotechnical thin films. Known measures, features, and methods can be found in this field. DESCRIPTION OF THE STATE OF THE ART

[0002] The present invention relates to a room temperature method for producing a PV layer sequence according to the preamble of the independent claim.

[0003] From a commercial perspective, a key aspect is that manufacturing takes place at room temperature. This significantly reduces manufacturing costs and offers a substantial advantage in production. However, it also means that the PV layer sequence cannot contain layers that have been precisely sintered or specifically compacted at elevated temperatures. However, the precisely adjusted, nanoscale planarity of a photovoltaically active layer composite is a key performance feature of established PV systems: PV layers are regularly precisely adjusted using vacuum plasma processes to ensure sufficient energy yield. However, room-temperature processes, which produce thin films—i.e., solid, continuous layer sequences—by printing, spinning, or flooding—i.e., by mechanical means—are generally unable to achieve planarity in the nanometer range in a controlled manner.The layers are uneven and often only flat in the micrometer range. Uneven layers that are only flat in the micrometer range can disadvantageously only use a planar PV junction adjusted by doping on a nanoscale for power generation with considerable losses. The inventors attribute this to the fact that in the field of photovoltaic, commercial production technology only a few documents and approaches seriously address RT manufacturing processes (RT = room temperature): JP H4-249379 A describes a PV device and a method for its production, wherein various reactions comprising deposition and etching processes are carried out under negative pressure using a CVD process (CVD = chemical vapor deposition, i.e. the gas phase serves to force a chemical reaction) in order to initially form the highly planar, planar PV basic structure.The disadvantage of the vacuum reaction chamber is that it necessitates expensive batch processing: only a certain number of substrates can be introduced into a vacuum reaction chamber at a time, then evacuated and, if necessary, dried, and finally removed again after coating under a reactive gas atmosphere. Another disadvantage is that the substrates to be coated must be kept at precisely controlled temperatures during coating to ensure that the same type and thickness of reactively formed layer is always formed. Furthermore, this document teaches the final printing with a Cu electrode paste, which must be baked, i.e., the layer composite must be exposed to high temperatures during contacting, whereby both the layers of the PV-active layer and the layers intended to form the electrodes are compacted and sintered to form an electrically sufficiently conductive and contacted overall cell.The disadvantageous thermal compaction step in particular results in high costs and disadvantages, because impurities and tiny contaminants are also subject to diffusion at the sintering temperatures that sinter copper pastes into a conductor track. Therefore, such manufacturing methods require the use of expensive, high-purity reactants that are free of impurities even during the final sintering step. Otherwise, the impurities would diffuse into the PV-active layer and weaken or even completely destroy it.

[0004] Similarly, CA 2 467 690 A proposes a printable hot-melt adhesive mixture that can be applied as an electrode structure and / or contact to electrical thin-film sequences, particularly PV layer sequences. The conductive paste contains conductive lead-glass particles, onto whose surface silver or aluminum flakes are deposited; this base mixture is fixed with a thermoplastic matrix. However, the disadvantage here is that all organic components must be subsequently burned out at 650 °C to 900 °C, otherwise sufficient conductivity and stability of the layer cannot be guaranteed.

[0005] The abstract of CN 10 329 3600 A discloses a method for forming five optical layers that specifically introduce or exit light and are suitable for PV or display devices. A polymer is printed onto a polyimide layer in the desired arrangement and spatial shape and is then heated to polymerization temperature. Through the targeted arrangement and modification of molecular chains, the refractive index of the optical layer can be adjusted in a direction-dependent manner, so that the optical cover layer no longer needs to be subsequently etched or structured. A disadvantage here, too, is that a final heating step is required to ensure complete polymerization. Furthermore, this document offers no indication as to whether and how such methods could be applied to a complete PV layer composite, in particular to a PV-active layer or layer combination.

[0006] Similarly, TW 2014 42 271 A discloses in its abstract a sealing system for PV modules in which a finished PV module is placed on a substrate and coated with UV-curing adhesive in various colors at room temperature using an inkjet printing station, while simultaneously sealing it firmly to the substrate. A disadvantage here is the use of a conventional, established PV-active layer as the module, meaning the manufacturing process for the power-supplying, PV-active layer is carried out in an established and costly manner, with the disadvantages already outlined.

[0007] The abstract of CN 10 321 434 0 A discloses a triptycene system that can be prepared as a nanoscale, aqueous dispersion via a sol-gel process. The aqueous dispersion can provide 50 nanometer to 200 micrometer-sized agglomerates of triptycene, thus offering semiconductor properties that can be printed into specific areas via the aqueous dispersion.

[0008] "Printable" encompasses—also within the meaning of the present invention—conventional printing systems, i.e., airbrush spray heads, inkjet print heads, electrostatic spraying of inks or color pigments, pad printing, lithographic printing, flexographic printing, offset printing, and even thermal sublimation printing, which can apply pigment inks via a meltable thermoplastic base. Triptycene, however, has the disadvantage of containing benzene groups; it is derived from dehydrobenzene and anthracene. Such systems regularly contain byproducts that slowly outgas from the matrix of the main product over time.Consequently, such organic, electrotechnical thin films are generally not stable in the long term, show a strong, initial deterioration of the electrotechnical properties in their corrosion behavior and contain components that must be declared, such as benzene, which, as volatile, organic components, often abbreviated as VOC, can outgas from the layer composite, endanger those present and further impair or even destroy adjacent layers.

[0009] CN 103 839 605 A discloses in its abstract a silver-graphene-based conductivity dispersion. This base is dispersed in an organic resin with crosslinkers and thinners, thus providing a printable, organic paste. A disadvantage of these resins is that they are only roughly adjusted to a medium molecular weight; they regularly contain VOCs and frequently potentially carcinogenic benzenes and their derivatives. Furthermore, adhesives containing thinners are dispersion adhesives: they cure by evaporation of the thinner / solvent, which cannot occur quickly and completely at room temperature and thus results in continuous evaporation of the thinner over time. Incomplete curing and the risk of long-term VOC release are known and typical disadvantages of such resin systems.

[0010] The application of pastes by screen printing is known from DE 10 2012 107 100 A1. The disadvantage is that these pastes must be converted into a continuous volume layer by sintering at a few hundred degrees Celsius. Organic components must also be destroyed by prolonged heating in order to even obtain the inorganic, continuous layers.

[0011] DE 10 2007 014 608 A1 discloses a semiconducting film that is thermally treated during production. In one process step, the particles are at least partially sintered. Similar to established processes, a conventional high-temperature furnace is replaced by an alternative and less voluminous energy source (preferably laser pulses according to paragraph 50). However, sintering is always intended, even if the pores may remain larger. Consequently, this process also requires the energy, equipment, and protective devices required for sintering processes.

[0012] The object of the present invention was therefore to overcome the disadvantages of the prior art and to provide a method which, despite industrial process control at room temperature and large-area fabrication, can provide thin films which provide a PV-active layer in a finished, contactable layer composite.

[0013] This object is achieved according to the features of the independent claim. Advantageous embodiments will become apparent from the following description. SUMMARY OF THE INVENTION

[0014] According to the invention, a PV layer sequence is obtained by a room temperature method according to claim 1; this comprises printing the PV layer sequence as a thin-film sequence at least including contact electrodes at room temperature in a continuous printing process, printing at least one aqueous solution and / or mixture comprising electrically conductive and / or semiconductive, inorganic agglomerates and curing them with an accompanying chemical reaction to form a PV-active layer, wherein again during the reaction nanoscale structures comprising at least one structure selected from the group consisting of chains, networks, network tubes, vacancies, pores were formed in the PV layer sequence.

[0015] The room temperature process for producing electrotechnical PV thin films, in which electrically conductive and / or semiconducting, inorganic agglomerates are provided in a dispersion over a large area and cured to form a layer, thus comprises that the curing is carried out at room temperature and the curing is accelerated by exposure to at least one reagent, whereby a PV layer sequence is formed. DESCRIPTION OF THE INVENTION AND ADVANTAGEOUS FEATURES

[0016] A PV layer sequence is accessible via the method claimed here.

[0017] The PV layer sequence according to the invention is obtained using a room temperature process. "Room temperature" is within the acceptable and usual range for humans and is around 25 degrees Celsius + / - 5 degrees Celsius in Europe. At this temperature, the PV layer sequence is formed as a thin-film sequence.

[0018] For the purposes of the present invention, 'thin film' encompasses layers in the micrometer range, whose layer thicknesses can be meaningfully specified in micrometers and deviate within no more than two orders of magnitude. The PV layer sequence, including at least the contact electrodes, is printed at room temperature in a continuous printing process. This creates a finished PV layer sequence that only needs to be connected to an existing system to collect and utilize photovoltaic power.

[0019] During the manufacturing process, at least one aqueous solution and / or mixture comprising electrically conductive and / or semiconducting inorganic agglomerates is printed and cured to form a PV-active layer under an accompanying chemical reaction. Printing a reactive solution or mixture significantly shortens the curing time, making production times comparable to those in industrial printing possible for the first time.Furthermore, the inventors assume that curing typically occurs most rapidly at the surface of a thin film, thereby creating a gradient within the thin film itself, which can meaningfully explain the electrotechnical properties: A gradient of vacancies and / or reaction products can create an electrochemical driving force in conductive and / or semiconducting agglomerates, which can meaningfully explain why layers produced in this way improve charge separation, support PV effects at PN junctions, and can also exhibit diode-like properties. In addition, nanoscale structures comprising at least one structure selected from the group consisting of chains, networks, network tubes, vacancies, and pores in the PV layer sequence are formed in the PV thin film during the reaction.Particularly advantageous is the simultaneous implementation of both reactively assisted curing and a reaction that forms nanoscale structures. This allows for the creation of nanoscale structural gradients, concentration gradients, and size distributions for nanostructure elements. The inventors attribute this to the fact that the measurable electrical properties indicate multiple excitation processes within a band gap. The low production temperature provides an additional advantage: Even with only technically pure reactants (purities of 95% to 99%, preferably 99% + / - 0.5% for large-scale industrial production), functioning, stable PV layer sequences can be obtained, since the PN junctions printed and / or chemically generated during production are not destroyed by diffusing impurities during subsequent sintering.Furthermore, the inorganic basic structure of the agglomerates, which essentially form the layer sequence, can explain the improved stability: Layer sequences produced in this way, after a final, slightly acidic sealing at temperatures of around 160 degrees Celsius, demonstrated typical performance values, showing no initial degradation in the climate chamber test. Specific PV layer sequence samples remained stable in performance for over 1000 hours, which the inventors attribute to the stable, inorganic agglomerate matrix. The PV layer sequences obtained in this way are therefore available at a fraction of the usual production price, both in terms of the required production facility and in terms of the cost of the necessary materials. They demonstrate significantly better long-term stability without initial degradation.

[0020] The thin-film sequence with the PV layer sequence according to the invention preferably has a PV-active layer which generates at least 4% of its open-circuit voltage, preferably 5% to 18% of its open-circuit voltage, particularly preferably 10 ± 4% of its open-circuit voltage, in the long-wave range of the visible spectral range, preferably in the spectral range greater than 1200 nm, particularly preferably in the range from 1500 nm to 4000 nm. If a PN junction is formed as described above with an accompanying reaction, nanostructures directly at the junction can additionally modify the band gap. Long, semiconducting to conductive nanostructures can be regarded as additional, long-wave quantum dots or wells which generate additional levels within the band gap. The inventors attribute this to the fact that they have already succeeded in producing thin-film sequences which generate energy only at long wavelengths of the visible light spectrum.

[0021] The thin-film sequence with a PV layer sequence is preferably characterized in that the entire thin-film sequence is free of volatile, organic components, contains no toxic heavy metals, preferably no selenium, arsenic, lead, cadmium, indium, or gallium as additives or added dopants, the PV layer sequence has a terrestrial efficiency of at least 10 ± 4%, and the PV layer sequence can be applied to a paper-like, flexible carrier. Volatile, organic components include plasticizers, long-chain alcohols, and polyfused hydrocarbons, which, as long-chain and heavy molecules, can outgas over time and harm both the cell and people present. Inorganic agglomerates are preferably free of toxic heavy metals; in particular, selenium, arsenic, lead, cadmium, indium, or gallium are not included as additives or added dopants.

[0022] The particularly advantageous PV layer sequences thus obtained have demonstrated a terrestrial efficiency of at least 10 ± 4% in specific samples. By using blends and application techniques familiar from the printing sector, application to paper is the simplest and fastest way to produce initial test samples. These samples demonstrated a flexibility and stability otherwise typical only of print products. Since such print products can also be printed on transfer films and / or label films and then finally applied to the actual carrier, the PV layer sequence can be applied in the same direction to a paper-like, flexible carrier. Corresponding self-adhesive films with electrotechnical thin films have already been produced.

[0023] The room temperature method according to the invention for producing electrotechnical PV thin films according to claim 1, in which electrically conductive and / or semiconductive, inorganic agglomerates are provided in a dispersion over a large area and cured to form a layer, comprises that the curing is carried out at room temperature and the curing is accelerated by exposure to at least one reagent, whereby a PV layer sequence is formed.

[0024] Preferably, the method is characterized in that a PV-active layer is formed on a carrier layer by providing a flowable mixture or solution, applying it in a thin layer, preferably printed, and finally curing it under accompanying reaction, supported by at least one measure, which at least one measure is selected from the group consisting of UV exposure, exposure to CO2, exposure to acidic gases, exposure to basic gases, exposure to oxidative gases, exposure to reducing gases, exposure to acid chlorides, exposure to urea solutions, exposure to metal oxide dispersion, exposure to metal carbonyls, exposure to metal complex compounds, exposure to metal compounds, exposure to metal salts, exposure to water, exposure to desiccant, exposure to drying gas, exposure to inert gas,Exposure to dry air.,

[0025] Preferably, the method is characterized in that a PV-active layer is at least partially arranged on a carrier layer which has at least one region which has at least one layer selected from the group consisting of conductive copper layer, conductive graphite agglomerate layer, conductive silver agglomerate layer, conductive gold agglomerate layer, conductive metal oxide agglomerate layer, conductive glass agglomerate layer, conductive graphene layer, conductive CNT layer, conductive SWCNT layer, conductive MWCNT layer.

[0026] According to the invention, the method is further characterized in that the method is carried out in a printing machine.

[0027] According to the invention, the method is further characterized in that a PV-active layer has an inorganic matrix with an interpenetrating organic network.

[0028] The method is preferably characterized in that the inorganic matrix comprises at least one type of agglomerate, preferably oxidized agglomerate, which is selected from the group consisting of silica agglomerates, basic silica agglomerates, acidic silica agglomerates, sodium waterglass agglomerates, potassium waterglass agglomerates, bromine agglomerates, iodine agglomerates, halogen agglomerates, carbon agglomerates, silicon agglomerates, germanium agglomerates, tin agglomerates, lead agglomerates, boron agglomerates, aluminum agglomerates, gallium agglomerates, indium agglomerates, phosphorus agglomerates, arsenic agglomerates, antimony agglomerates, sulfur agglomerates, selenium agglomerates, Tellurium agglomerates, bismuth agglomerates.

[0029] According to the invention, the method is further characterized in that an organic matrix has at least one cross-linked component which is selected from the group consisting of polyamide component, polyacrylate component, polyol component, polyester component, polyhexose component, polyamino acid component, swellable polyhexose component, red algae extract, agar-agar, corn starch, potato starch, starch, carrageenan, tragacanth, swellable polysaccharide, gum arabic, alginates, pectin, swellable polypeptide, gelatin, carboxymethylcellulose, hydroxyethylcellulose, polyacrylics, polycarboxylic acids, polyethers, polyamides, polyimides, organosilicon compound with polymerizable side group based on methacrylic acid, organosiloxane.

[0030] The process is preferably characterized in that at least one reaction is carried out as an accompanying reaction, which is selected from the group consisting of oxidation with a halogen, oxidation under UV exposure, oxidation under UV exposure with wavelengths less than 385 nm, oxidation under UV exposure with a deuterium lamp, oxidation under UV exposure with a UV LED at 365 nm, oxidation with atmospheric oxygen, oxidation under UV exposure with a mercury vapor lamp, oxidation under UV exposure with wavelengths around 254 nm, oxidation under UV exposure with wavelengths around 185 nm, crosslinking and oxidation under UV exposure, release of organic acids under condensation, release of organic alcohols under condensation, release of alcohols with oxide formation.

[0031] Preferably, the method is characterized in that nanoscale poly-ions are introduced before or during curing, wherein the poly-ions comprise at least one type of poly-ion selected from the group consisting of polyhalide ions, interhalide ions, poly-sulfide ions, poly-iodo-iodide ions, conjugated carbon ions, graphene ions, CNT ions.

[0032] The process is preferably characterized in that the length of the - preferably chain-shaped - poly-ions is adjusted to an average chain length.

[0033] The method is preferably characterized in that a PV-active layer comprises at least a portion of one type of carrier molecule, the carrier molecule being selected from the group consisting of ion-absorbing framework polymers, Li-ion-absorbing framework polymers, ion-exchange resins, ion-exchange polymers, ion-exchange glasses, halogen ion-exchange glasses, halogen ion-exchange silicates, and iodophores. The method is preferably characterized in that a PV-active layer comprises at least one further sensitizer.

[0034] According to the invention, the method is further characterized in that an accompanying reaction of a PV-active layer applied to a conductive component comprises a surface oxidation of a metallic component.

[0035] Preferably, the process is characterized in that the oxidation comprises at least one reaction selected from the group consisting of formation of CuI on a particulate copper component, formation of Cu2O on a particulate copper component, formation of Ag2O on a conductive component, formation of ZnS on a metallic component, formation of SnO on a metallic component, formation of titanium four-oxide compounds on a conductive component, formation of titanium four-oxide compounds with low-valent metal oxide admixture. DETAILED EXPLANATION OF THE INVENTION USING EXEMPLARY EMBODIMENTS

[0036] In an advantageous embodiment, the room temperature process for producing an electrotechnical, PV-active thin-film sequence, wherein electrically conductive and / or semiconducting, inorganic agglomerates are provided in a dispersion over a large area and cured to form a layer, is characterized in thatthe curing is carried out at room temperature, the curing is accelerated by applying at least one reagent, the process is carried out in a printing machine, a PV layer sequence is formed, wherein in turn a PV-active layer is formed on a carrier layer by providing a flowable, aqueous mixture or solution, the mixture or solution comprises at least one inorganic agglomerate type selected from the group consisting of silica agglomerates, basic silica agglomerates, acidic silica agglomerates, sodium waterglass agglomerates, potassium waterglass agglomerates, halogen agglomerates, iodine agglomerates, preferably a combination of silica agglomerate with an adjusted pH value and halogen agglomerate, wherein the mixture or solution comprises at least one organic, crosslinkable component as a further constituent,whose crosslinkable molecular part comprises at least one molecular part selected from the group consisting of lactam part, acrylic part, polysaccharide part, silicon-organic compound with polymerizable side group based on methacrylic acid, organosiloxane, organosilyl acetate, and the mixture or solution is printed in a thin layer and finally cured under accompanying reaction, assisted by UV exposure and exposure to drying gas, whereby the PV-active layer forms an inorganic matrix with an interpenetrating, organic network.

[0037] In a further advantageous embodiment, the room temperature process for producing an electrotechnical, PV-active thin-film sequence, wherein electrically conductive and / or semiconductive, inorganic agglomerates are provided in a dispersion over a large area and cured to form a layer, is characterized in that a PV layer sequence is formed in a printing machine, whereby in turn a PV-active layer is formed on a carrier layer in which a flowable, aqueous mixture or solution is introduced, a mixture or solution with mutually reacting components is prepared, printed on in a thin layer, and finally cured while the reaction continues, whereby the PV-active layer forms an inorganic matrix with an interpenetrating, organic network with cross-linking binder bridges.

[0038] In a further advantageous embodiment, a PV layer sequence according to the invention was obtained as follows: At room temperature, during a printing process on a flexographic printing machine with a self-adhesive, two-layer label paper as the carrier and with multiple printing stations, an at least partially metallic thin layer—in this case a copper layer and / or a silver layer—was first formed on a reductively adjusted graphite-carbon layer on the paper. As a further printing paste for the aforementioned machine, an electrically conductive and / or semiconductive, inorganic agglomerates in a dispersion was prepared as follows: A partially crosslinkable polysaccharide-starch ether was adjusted to a low pH value as a secondary component with an ascorbic acid-hydrochloric acid mixture in dispersion. The pH value was monitored using an added color indicator.The remaining solid was then dissolved in distilled water with constant stirring and mixed with a saccharide containing dextran to adjust the viscosity. The acidic to strongly acidic solution was mixed with silica as the main component and adjusted to a strongly basic pH with sodium hydroxide solution, i.e., until the indicator changed color, while stirring. The silica coagulates / precipitates and forms inorganic agglomerates. The strongly basic dispersion is reductively adjusted with the addition of a metal that dissolves in alkalis—in this example, a small amount of completely soluble aluminum together with an equal amount of iodine-potassium iodide. The potassium iodide dissolves concomitantly, forming a colored complex, allowing the dissolution kinetics in the aqueous dispersion to be monitored both optically and via the conductivity of the mixture.The aqueous, still-reactive, and reductively adjusted dispersion was added as a printing paste to a subsequent printing station of the flexographic printing machine. This means that the reductively adjusted paste is printed directly after the metal layer has been applied. After the reductive dispersion has been printed, the fresh, still-moist paste is dried under UV exposure with a mercury vapor lamp and exposure to dry air. UV exposure decolorizes the iodine complex, at least partially, releasing elemental iodine, which reacts with the surrounding matrix and any chloride ions present during curing. Furthermore, the iodine—like chlorine—can react with the previously printed metal layer on the underside.The inventors assume that, on the one hand, PN junctions form directly at the metal layer, and simultaneously, corresponding junctions can form along the inorganic agglomerates from the dissolved metal—here, aluminum—and the released halogens. The entire process is carried out in a flexographic printing press. The PV-active layer is formed on the carrier layer with at least a partial metal layer. Varying the amount of hydrochloric acid, potassium iodide, and reductively dissolved metal significantly influences the efficiency and performance of the PV-active layer and allows for optimization of its properties. The mixture or solution contains the polysaccharide component as a further component. The inventors assume that this component, as a secondary component, builds up an organic framework that also includes and can support halogen agglomerates and interhalogen agglomerates.The PV-active layer, printed in a thin layer and subsequently cured under an accompanying reaction supported by UV exposure and exposure to drying gas, thus formed an inorganic matrix as its main component with an interpenetrating organic network as a secondary component. The PV layer sequence was contacted on the top side with room-drying conductive silver; alternatively, printing with conventional, self-adhesive electrodes and / or with layers corresponding to the metal layer printed on the underside is also conceivable. It is crucial that the PV-active layer is not covered to ensure sufficient PV conversion of light to electricity. The fully contacted PV layer sequence was provided with leads and sealed in a laminator with an acrylate thermoplastic sleeve.The welded cell was tested for efficiency according to established Si standards and norms and demonstrated an efficiency of around 10 ± 4% with a low fill factor of around 0.3 to 0.4. The exploitable potential of the cell manufactured here is therefore in the range of 10% to 20% efficiency. In a climate chamber test based on IEC Standard 61215, the cell was exposed to strong sunlight with UV at 80°C and high humidity. No change in performance was observed over 1,000 hours. Only after the laminate weld, which was not optimized for outdoor use, peeled off and the humid atmosphere was in direct contact with the thin-film sequence for several hundred hours did a performance decrease of less than 6% become apparent.The inventors attribute the high stability (no initial performance decline) and the surprisingly stable performance, even in direct contact with a humid atmosphere, to the inorganic backbone: The agglomerates have formed solid contact points and bridges among themselves. The matrix is ​​extremely stable and hardly susceptible to sintering or corrosion processes. The cross-linked structure also explains the high flexibility of the product obtained by printing: The paper carrier can be rolled, bent, and folded like a traditional printed product without the printed thin-film sequence exfoliating or flaking.

[0039] Additional studies on the usable wavelengths further revealed that when increasing the power of a light bulb's radiation source, the present cell demonstrated significantly greater performance gains compared to a conventional Si PV cell: Whereas the Si cell delivers only 0.5 to 1 percent more power at increased brightness, the printed cell according to the invention was able to provide several percent more power. Furthermore, when the light bulb was switched off but still warm, the cell according to the invention showed a residual power of around 10% of the originally available open-circuit voltage, which decreased in the same direction as the temperature of the light bulb fell.The inventors attribute these superior performance characteristics to the morphology and a modified band gap structure: Firstly, the significantly larger surface area of ​​the printed agglomerates is capable of converting more photons under stronger light incidence; secondly, the PV-active, nanoscale structures arranged on the surface of the agglomerates make the present cell less sensitive to varying incident angles: Even at a steeply inclined incident angle, a significantly larger portion of the power can still be accessed than was the case with established, available Si cells. Furthermore, the residual efficiency, arranged at a long wavelength relative to the visible spectrum, indicates quantum dots and / or closely spaced energy levels within the band gap, which allow the conversion of long-wavelength photons. The inventors assume that the reactively formed, nanoscale structures modify the band gap here.This can reasonably explain why the cell described above was able to provide a usable, constant residual power using a warm light bulb, even in apparent darkness. INDUSTRIAL APPLICABILITY

[0040] A disadvantage of traditional printed PV layer cells is that they often require expensive vacuum preparation and thermal annealing or sintering steps during production, making the thin, doped vacuum layers highly susceptible to corrosion and contamination. The challenge was therefore to overcome these disadvantages and develop a suitable process and a suitable PV layer sequence. The solution is a room-temperature process in which aqueous dispersions are printed onto a substrate and cured under an accompanying reaction. This accompanying reaction forms gradients and nanoscale structures at the layer boundaries, creating a PV-active layer with typical performance and high stability. Efficiency levels of around 10% are stable and achievable without initial performance loss in climate chamber tests, and are consistently available with little fluctuation over a 20-year test period.The process is free of annealing or sintering steps, allows the use of technically pure, inexpensive starting materials, and makes the PV layer sequence available as a finished, highly flexible cell for a fraction of the usual investment required for production or distribution. For the first time, PV layer sequences can be produced completely analogously to the manufacture of a printed product. Thus, the invention offers extremely versatile applications, both in terms of production and use, in all areas where established PV thin films have previously been rejected as too expensive or too unstable.

Claims

1. Method for producing a PV layer sequence at room temperature, in which - without annealing or sintering steps, - aqueous dispersions are printed onto a carrier and cured in an accompanying reaction, - the PV layer sequence is printed as a thin layer sequence at least including contact electrodes at room temperature in a continuous printing process, - at least one aqueous solution and / or mixture comprising electrically conductive and / or semiconductive, inorganic agglomerates is printed and cured to form a PV active layer in an accompanying chemical reaction, - during the accompanying reaction, nanoscale structures comprising at least one structure selected from the group consisting of chains, nets, net tubes, spaces, pores are formed in the PV layer sequence, - the curing is accelerated by exposure to at least one reagent, - electrically conductive and / or semiconductive, inorganic agglomerates are provided planarly in a dispersion and cured to form a layer, wherein, however, - a PV active layer is formed on a carrier layer by a flowable, aqueous dispersion being provided, - the dispersion is prepared with components that react with each other and printed in a thin layer onto a conductive component, - the accompanying reaction of the printed layer involves a superficial oxidation of a metal component, - is finally cured while the reaction continues, wherein the PV active layer forms an inorganic matrix with an interpenetrating, organic network having crosslinking binder bridges and the organic matrix has at least one cross-linked component which is selected from the group consisting of polyamide component, polyacrylate component, polyol component, polyester component, polyhexose component, polyamino acid component, swellable polyhexose component, red algae extract, agar agar, corn starch, potato starch, starch, carrageenan, tragacanth, swellable polysaccharide, gum arabic, alginates, pectin, swellable polypeptide, gelatin, carboxymethylcellulose, hydroxyethylcellulose, polyacrylics, polycarboxylic acids, polyethers, polyamides, polyimides, silicon-organic compound with polymerizable side group based on methacrylic acid, organosiloxane.