Process for the formation of a perovskite layer in particular for a photovoltaic cell
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- SINGULUS TECHNOLGIES AG
- Filing Date
- 2024-07-22
- Publication Date
- 2026-06-10
AI Technical Summary
Current methods for forming perovskite layers in solar cells are costly, complex, and difficult to scale industrially, often requiring hazardous solvents and complex equipment, which limits their industrial implementation.
A two-stage process involving a first perovskite pre-product layer on a carrier substrate, followed by a second pre-product layer applied as a solution film using a roll process with a harmless solvent like water, which is then heated to initiate a chemical reaction, forming a perovskite seal without generating aerosols or requiring expensive equipment.
This approach allows for the cost-effective and industrially viable formation of perovskite layers with reduced apparatus complexity, using safe and inexpensive solvents, and enables the production of perovskite solar cells with high chemical stability and radiation resistance.
Smart Images
Figure EP2024070791_06022025_PF_FP_ABST
Abstract
Description
[0001] Singulus Technologies AG
[0002] Hanauer Landstr. 103, 63796 Kahl am Main, Germany
[0003] METHOD FOR FORMING A PEROVSKITE LAYER
[0004] ESPECIALLY FOR A SOLAR CELL
[0005] FIELD OF THE INVENTION
[0006] The present invention relates to a method for forming a perovskite layer. Furthermore, the invention relates to a method for manufacturing a solar cell with a perovskite layer formed in this way.
[0007] TECHNICAL BACKGROUND
[0008] Perovskite layers, i.e. thin layers of perovskite material, can exhibit, among other things, interesting electrical and optical properties, which make them suitable for a wide variety of applications.
[0009] In particular, solar cells have recently been developed that utilize an absorber layer made of perovskite material to absorb light and convert the energy contained in the light into electrical energy. These so-called perovskite solar cells promise high efficiencies with low material costs and simple production.
[0010] Various processes are known for the formation of perovskite layers, particularly for solar cells. For example, chemical substances that can react with one another to form a perovskite material and which are also referred to herein as perovskite precursors, perovskite precursors or perovskite educts, can be applied to a substrate in a single process step and then caused to react chemically there, for example by supplying energy in the form of heat. In such a single-step process, the perovskite layer precursors can, for example, be vapor-deposited onto a substrate in a joint vapor deposition process. However, such vapor deposition processes are often difficult to implement on an industrial scale, require complex equipment and / or are cost-intensive. Alternatively, wet-chemical deposition processes have been proposed for the formation of a perovskite layer in a single-step process.However, technical difficulties and / or high costs often stand in the way of industrial implementation of these processes.
[0011] Alternatively, perovskite precursors can be applied to a substrate in a two-step process before being subjected to a chemical reaction. This involves first depositing a first perovskite precursor layer onto a substrate, followed by a second perovskite precursor layer on top.
[0012] To form the two perovskite precursor layers, different technologies can be used.
[0013] For example, a perovskite precursor layer can be formed by depositing suitable chemical substances using physical vapor deposition (PVD) or chemical vapor deposition (CVD). However, this often requires complex equipment, and the associated high costs and / or low throughput often make such processes unattractive for industrial implementation. Alternatively, at least one of the perovskite precursor layers can be formed using wet-chemical processes. The use of different wet-chemical deposition processes is conceivable in this case.
[0014] For example, a so-called spin coating is often used on a laboratory scale. A viscous solution containing the substances required for the perovskite precursor is applied to a rotating substrate. Centrifugal forces then spread the solution into a perovskite precursor layer of homogeneous thickness. However, such an approach is usually only applicable to coating small-area substrates and, due to its lack of mass production, is particularly unsuitable for industrial implementation to form perovskite layers.
[0015] Alternatively, perovskite layers can also be applied wet-chemically using so-called slot-die extrusion dies. Such processes are also known as slot-die coating. A solution that should be sufficiently viscous and contains the substances required for the perovskite precursor is extruded through a wide slot die onto the surface of a substrate. However, the relatively high equipment required for this, as well as limitations of the viscous solutions that can be used in this case, make the industrial implementation of such deposition processes for the formation of perovskite layers unattractive.
[0016] In addition, in the two wet-chemical deposition processes mentioned above, the reactants are often dissolved in solvents such as dimethylformamide, which are relatively hazardous substances that are, for example, flammable and / or toxic. This can complicate industrial implementation of these processes, for example due to high costs or the complex equipment required. In particular, many safety-related aspects, such as compliance with regulations (e.g., ATEX), can lead to increased costs when designing a plant for this purpose. The solvents themselves are also often expensive, which can increase the manufacturing costs of the entire process.
[0017] In another approach, the reactants are dissolved in a solvent and applied to a substrate using a spraying process, also known as spray coating. However, this generally generates aerosols, which can be difficult to extract and / or prevent a portion of the reactants from reaching the perovskite layer being created, thus reducing the deposition efficiency.
[0018] SUMMARY OF THE INVENTION AND EMBODIMENTS
[0019] There may therefore be a need for an alternative approach by which a perovskite layer can be formed and by which at least some of the aforementioned problems of previous approaches can be avoided or reduced. In particular, there may be a need for a process by which a perovskite layer can be produced at low cost, with low equipment requirements, and / or in an industrially feasible manner. Furthermore, there may be a need for a method for manufacturing a solar cell using such a method for forming a perovskite layer.
[0020] The aforementioned needs can be at least partially met by the subject matter of one of the independent claims of the present application. Advantageous embodiments are specified in the dependent claims and the following description.
[0021] According to a first aspect of the present invention, a method for forming a perovskite layer on a carrier substrate is described. The method comprises at least the following process steps, preferably in the specified order: (i) providing the carrier substrate coated with a first perovskite precursor layer comprising a first perovskite precursor, and
[0022] (ii) coating the first perovskite precursor layer on the carrier substrate with a second perovskite precursor layer by
[0023] - applying a solution containing a second perovskite precursor forming the second perovskite precursor layer to a roll, and
[0024] - transferring the solution as a solution film forming the second perovskite precursor layer to the first perovskite precursor layer by rolling the roll along the first perovskite precursor layer, and
[0025] (iii) heating the first perovskite precursor layer together with the solution film above a predetermined reaction temperature limit to initiate a chemical reaction between the first perovskite precursor and the second perovskite precursor.
[0026] According to a second aspect of the present invention, a method for manufacturing a solar cell is described. The method comprises at least the following process steps, preferably in the specified order:
[0027] - forming a perovskite layer on a surface of a carrier substrate which has been previously coated with a first perovskite precursor layer, by means of the method according to one of the preceding claims, and
[0028] - Forming electrical contacts to dissipate electrical charge carriers from the perovskite layer.
[0029] Embodiments of the invention may be considered, among other things and without limiting the invention, to be based on the ideas and findings described below. By way of introduction, a basic idea for embodiments of the invention described herein will be briefly explained, whereby this explanation is to be interpreted as merely a rough summary and not as limiting the invention:
[0030] As already indicated, the aim is to provide an advantageous and, in particular, industrially applicable process for forming perovskite layers, for example, for the production of solar cells. For this purpose, a two-stage process is proposed. A first perovskite precursor layer is formed in any desired manner and pre-applied to a carrier substrate. A second perovskite precursor layer is then applied to the carrier substrate provided with this first perovskite precursor layer in a second process step. For this purpose, a special wet-chemical process is selected in which a solution containing the second perovskite precursor is applied to a roller and then transferred to the first perovskite precursor layer in the form of a solution film by rolling the roller along the first perovskite precursor layer.As explained in more detail below, the roller can be specially designed as an absorbent roller to efficiently absorb the solution and release it in a controlled manner. Furthermore, a safe and inexpensive solvent, such as water, can be used for the solution. After the solution film has been applied in this way, the first perovskite precursor layer, together with the solution film, is heated above a predetermined reaction temperature limit. Above this temperature, a chemical reaction occurs between the first and second perovskite precursors, whereupon they form the desired perovskite layer.
[0031] The proposed approach can be implemented using a relatively simple technical system. Furthermore, hazardous, harmful, and / or expensive solvents can be avoided. Furthermore, the proposed rolling process generally does not generate aerosols. Possible features of embodiments of the invention and the resulting advantages are described in detail below.
[0032] The perovskite layer to be formed using the method described herein can, in principle, be produced with any desired dimensions. For example, the area of the perovskite layer can range from a few square millimeters to several square meters. Preferably, the area of the perovskite layer can be between 5 cm 2 and 5 m 2 , more preferably between 200 cm 2 and 2 m 2The layer thickness can be between 1 nm and 1 mm, preferably between 100 nm and 1 pm. The perovskite layer is generally not self-supporting, but is supported by a carrier substrate.
[0033] The carrier substrate can, in principle, have any dimensions and be made of any material. For example, the carrier substrate can have the same surface area as the perovskite layer to be formed on it. However, the carrier substrate can also be larger than the perovskite layer to be formed, so that the latter only covers partial areas of the carrier substrate. The carrier substrate is usually significantly thicker than the perovskite layer. For example, the thickness of the carrier substrate is usually greater than 0.1 mm, often greater than 0.5 mm, greater than 1 mm, or even greater than 3 mm, but usually less than 2 cm or less than 1 cm.
[0034] The material and geometry of the carrier substrate can be selected such that, on the one hand, it provides sufficient mechanical support for the perovskite layer to withstand the forces acting on the perovskite layer during operation. On the other hand, the carrier substrate should be able to withstand the conditions encountered during formation of the perovskite layer, such as temperatures, attack by the chemicals used, etc. Furthermore, the thermal expansion coefficient of the carrier substrate should not differ excessively from that of the perovskite layer formed on it. In practice, thin glass panes have proven suitable for the carrier substrate for many applications. In some examples, the glass itself can have electrically conductive coatings. However, carrier substrates made of semiconductor material, particularly in the form of silicon disks or wafers, can also be used.As described in more detail below, a fully processed solar cell, such as one constructed from a silicon wafer, can serve as a carrier substrate. However, carrier substrates made of other materials, such as plastic, ceramic, metal, etc., are also conceivable.
[0035] The carrier substrate is pre-coated with a first perovskite precursor layer. Any coating method can be used for this purpose. For example, the first perovskite precursor layer can be deposited using PVD or CVD processes. The carrier substrate pre-processed by coating with the first perovskite precursor layer is then prepared for the process described herein.
[0036] A second perovskite precursor layer is then applied to the first perovskite precursor layer. This involves an application process in which a solution is applied to the first perovskite precursor layer using a roller and distributed over the entire surface as evenly as possible.
[0037] The solution contains the second perovskite precursor dissolved in and / or mixed with a liquid solvent. The solution can be saturated with the second perovskite precursor to a certain extent, for example, more than 10%, more than 30%, more than 60%, more than 80%, more than 90%, more than 95%, or even completely saturated or even supersaturated. The solution can be at room temperature or ambient temperature. Alternatively, the solution can be heated to a higher temperature or cooled to a lower temperature than ambient temperature.
[0038] The solution is first applied to the roller and then transferred from the roller as a solution film to the first perovskite precursor layer on the carrier substrate. To do this, the roller coated with the solution is moved along the perovskite precursor layer so that, as it rolls, it transfers at least part of the solution stored on or in it as a solution film to the surface of the first perovskite precursor layer.
[0039] The first perovskite precursor layer, thus covered with the solution film, is then specifically heated. In particular, heating occurs above a predetermined reaction temperature limit. This reaction temperature limit can depend on the material-specific properties of the first and second perovskite precursor and represents the temperature above which a chemical reaction occurs between the two perovskite precursors, ultimately forming the desired perovskite layer. This reaction temperature limit is usually above 50 °C, above 60 °C, or above 70 °C, but more commonly below 150 °C, below 130 °C, below 110 °C, or below 90 °C. During this heating, the solvent contained in the solution simultaneously evaporates.
[0040] According to one embodiment, the solution is aqueous. An aqueous solution is usually easy to handle and inexpensive to provide. In particular, the aqueous solution should be free of harmful, hazardous, and / or difficult-to-dispose chemicals.
[0041] For example, according to one embodiment, the solution may contain only water and the second perovskite precursor. In particular, it has been observed that chemicals that exhibit high solubility in water can be used as the second perovskite precursor. Accordingly, an easy-to-handle and cost-effective mixture of water and such a perovskite precursor, to which no other chemicals, or at least no significant amounts of other chemicals, are added, can be used as the solution.
[0042] According to one embodiment, the second perovskite precursor is inorganic. In other words, the second perovskite precursor is free of carbon compounds. It has been recognized that inorganic substances are particularly well suited for use in the process described herein. Furthermore, it has been recognized that perovskite layers containing inorganic substances can exhibit advantageous properties such as high chemical stability, high radiation resistance, and thus a long service life.
[0043] In particular, according to a further specific embodiment, the second perovskite precursor can be a cesium halide salt. Cesium halide salts have been identified as particularly suitable for use in the solution in the process described herein. Bromine can preferably be used as the halogen moiety. For example, cesium bromide (CsBr) can be used as the cesium halide salt. Alternatively, other halogen moieties such as chlorine or iodine, or mixtures of different cesium halide salts, can also be used.
[0044] According to one embodiment, the first perovskite precursor is also inorganic. This allows, in particular, the entire perovskite layer to be constructed of inorganic material. Thus, the entire perovskite layer can be chemically stable, radiation-resistant, and / or durable.
[0045] In particular, according to a more specific embodiment, the first perovskite precursor can be a lead halide salt. The halogen component can be bromine, chlorine, or iodine. The lead halide salt can be, for example, lead dibromide (PbBr2).
[0046] According to one embodiment, the roll can be provided with absorbent material at least on one outer circumferential surface. In other words, the roll can be designed such that it can absorb the solution at least in an outer volume region adjacent to its outer circumferential surface. The solution applied to the roll therefore does not form, or at least not exclusively, a film that forms along the outer circumferential surface of the roll, as would be the case, for example, with purely plastic rolls with a smooth surface. Instead, the solution applied to the roll is at least partially, preferably predominantly or even completely, absorbed into the absorbent material of the roll and thus absorbed within the volume of the roll within the outer circumferential surface.
[0047] The way in which the absorbency of the material of the roll is formed can determine how and in what quantities the solution is absorbed therein. The roll can consist entirely of the absorbent material. Alternatively, the roll can have a core made of a different material, onto which the absorbent material is then applied as an outer absorbent layer along the circumferential surface of the entire roll. The outer absorbent layer can, for example, have a thickness which makes up at least 5%, preferably at least 10%, at least 20% or even at least 30% of the roll diameter. The roll diameter can, for example, be in a range from 0.5 cm to 20 cm, preferably a range from 1 cm to 10 cm or a range from 2 cm to 5 cm.
[0048] According to a specific embodiment, the absorbent material (17) can be porous. In other words, the absorbent material can have pores into which the solution can be stored. For example, the absorbent material can have a porosity of more than 5%, preferably more than 10%, more than 20%, more than 30% or even more than 50%. The porosity indicates the ratio of pore volume to total volume. Preferably, the absorbent material is open-pored, i.e. adjacent pores are connected to one another. In particular, the absorbent material should be open-pored on the outer peripheral surface of the roll. A roll formed with such a porous absorbent material can also be referred to as a sponge roll.
[0049] According to one embodiment, the roller can be formed from a polymer material. Such a polymer material can simply be formed as an absorbent and, in particular, porous material. For example, the roller can be formed from polyurethane foam or coated on its surface. Alternatively, the absorbent material can be formed from other foams, cellulose, or other synthetic polymers.
[0050] According to one embodiment, the solution can be applied to the roller at a first position, which is spaced apart from a second position at which the roller contacts the first perovskite precursor layer. A pressing device can be pressed against an outer circumferential surface of the roller in the circumferential direction between the first position and the second position in such a way that the amount of solution carried along by the roller during rolling and applied to the first perovskite precursor layer is adjustable.
[0051] In other words, the amount of solution carried by the roll and particularly absorbed in the absorbent material of the roll can be adjusted and thus limited by using a special squeezing device to specifically squeeze out any excess volume of solution applied from the roll.
[0052] The squeezing device presses against the outer circumference of the roll at a third position, which differs from both the first position at which the solution is applied to the roll and the second position at which the roll rests against the perovskite precursor layer, and which is spaced apart from the first position and the second position along the circumference of the roll and lies circumferentially between these two positions.
[0053] By squeezing solution out of the roller at the third position, only a reduced volume of solution is retained in the roller at least in a fourth position, which is located circumferentially and relative to the rotational direction of the roller behind the third position. This reduced volume can be influenced or controlled by adjusting the contact pressure of the squeezing device.
[0054] Since the amount of solution transferred to the first perovskite precursor layer as the roll unwinds generally depends on the total amount of solution carried in the roll, this amount of transferred solution can be adjusted and limited in this way. In addition, the contact pressure with which the roll is pressed against the carrier substrate and / or the flow rate with which the solution is applied to the roll also influence the amount of transferred solution, so that these parameters can also be specifically adjusted. Generally, care should be taken to achieve homogeneous wetting of the roll in the longitudinal direction. This ultimately prevents an excessive amount of solution, and thus an excessively thick solution film, from being transferred to the first perovskite precursor layer.
[0055] The squeezing device can, for example, be designed as an additional roller that is pressed against the outer peripheral surface of the roller that guides the solution. This additional roller can be rigid and have a hard, smooth peripheral surface and / or be non-absorbent. Alternatively, it can also be designed with a flexible surface and / or an absorbent surface. The two rollers can roll against each other.
[0056] Alternatively, the squeezing device can also be designed as a type of squeegee, which is pressed against the outer circumferential surface of the roll and slides along it.
[0057] A contact pressure or contact force between the squeezing device and the roller can be adjustable if necessary. By adjusting this contact pressure, the amount of solution remaining in the absorbent layer of the roller after squeezing can be influenced or adjusted. Additionally or alternatively, a contact pressure or contact force between the roller and the first perovskite precursor layer can be adjustable.
[0058] According to one embodiment, an excess of solution applied to the roll can be sucked off the roll with the aid of a suction device. The suction device can be arranged adjacent to the outer circumferential surface of the roll and configured to suck off excess solution there. The suction device can in particular be arranged at a fifth position which is located along the circumference of the roll between the first position at which the solution is applied to the roll and the third position at which the squeezing device presses a portion of the applied solution back out of the roll. By sucking off excess solution, it can be prevented, among other things, that it flows to unwanted locations, i.e., for example, flowing over a lateral edge of the roll.
[0059] By means of the method according to the first aspect of the invention, a perovskite layer can be formed, which can then be used in the manufacture of a solar cell according to the second aspect of the invention.
[0060] The solar cell can be formed as a pure perovskite solar cell. For this purpose, additional electrical contacts in the form of electrodes must be attached to the formed perovskite layer. These electrodes can be used to divert electrical charge carriers generated by the absorption of light in the perovskite layer and feed them into an external circuit. In addition to the electrical contacts, further layers or components can be formed on the perovskite layer. The process described herein is particularly suitable for producing perovskite solar cells based on inorganic perovskite layers.
[0061] According to a further embodiment, the carrier substrate can comprise a first solar cell, wherein the perovskite layer, together with the electrical contacts, is formed as a second solar cell. In other words, the carrier substrate can itself be a solar cell or comprise a solar cell, so that a further solar cell can then be formed on this existing solar cell using the perovskite layer formed thereon by the method described herein. The first solar cell can be referred to as a bottom solar cell and the second solar cell as a top solar cell, with both solar cells together forming a tandem solar cell.
[0062] In particular, the first solar cell can be a silicon solar cell, preferably a solar cell formed on a silicon wafer. Such silicon solar cells can be manufactured using long-established technologies, exhibit high efficiencies, and are highly reliable. A perovskite solar cell can be formed on such a silicon solar cell as a top solar cell. The two solar cells complement each other well with regard to their respective absorption spectra.
[0063] Alternatively, the first solar cell may be a thin-film solar cell, for example, based on a 111 V semiconductor. As another example, the first solar cell may be a CdTe solar cell or a CIGS solar cell.
[0064] It should be noted that possible advantages and configurations of embodiments of the invention are described herein partly with reference to a method according to the invention for forming a perovskite layer and partly with reference to a method for manufacturing a solar cell with such a perovskite layer. A person skilled in the art will recognize that the described features can be appropriately transferred, adapted, exchanged, or modified to achieve further embodiments of the invention.
[0065] BRIEF DESCRIPTION OF THE DRAWINGS
[0066] Embodiments of the invention will now be described with reference to the accompanying drawings, which are not intended to be limiting. Figures 1 (a) - (d) show successive stages of a method according to one embodiment of the invention.
[0067] Fig. 2 shows a roller arrangement as can be used in a method according to an embodiment of the invention.
[0068] The figures are merely schematic and not to scale. The same reference numerals designate identical or equivalent features in the various figures.
[0069] DESCRIPTION OF PREFERRED EMBODIMENTS
[0070] Fig. 1 shows successive stages of a process for forming a perovskite layer 1, by means of which a solar cell 29 is ultimately formed.
[0071] In a first step (see Fig. 1 (a)), a carrier substrate 3 is provided, which has previously been coated with a first perovskite precursor layer 5. A glass substrate, for example, is used as the carrier substrate 3. A layer of a lead halide salt in the form of a layer of PbBr2 has previously been applied to this by evaporation as the first perovskite precursor layer 5.
[0072] In the present case, a further layer in the form of an electrically conductive layer 37 was formed between the carrier substrate 3 and the first perovskite precursor layer 5. In addition or alternatively, further layers can be interposed, for example, in the form of an adhesive layer, a buffer layer, or the like.
[0073] In a second step (see Fig. 1 (b)), a solution 9 of cesium halide salt dissolved in water, in the form of, for example, CsBr, is applied to a roller 11. The solution 9 can be fed continuously via a feed device 45. In the example shown, the roller 11 is designed as a sponge roller and has absorbent material 17 along its outer circumferential surface 15. As the roller 11 rolls along the first perovskite precursor layer 5 on the carrier substrate 3, a portion of the solution 9 absorbed in the roll 11 is transferred to the surface of the first perovskite precursor layer 5, where it forms a solution film 13. A second perovskite precursor layer 7 then forms from this solution film 13 after the water has evaporated from the solution 9.
[0074] In a third step (see Fig. 1 (c)), the carrier substrate 3 together with the first perovskite precursor layer 5 and the solution film 13 is heated by means of a heater 43 above a predetermined reaction temperature limit of, for example, more than 60 °C in order to trigger a chemical reaction between the perovskite precursors contained in the two perovskite precursor layers 5, 7. The perovskite precursors react to form a perovskite and thereby form the desired perovskite layer 1 on the carrier substrate 3. The heater 43 can heat the carrier substrate 3 together with the perovskite precursor layer 5 and the solution film 13 from one side or from two opposite sides, for example from above, from below, or both from above and below. For this purpose, for example, several heating elements can be provided which are arranged along a travel path along which the carrier substrate 3 is successively displaced.For example, the heating elements can be arranged in segments between transport rollers that convey the carrier substrate. The carrier substrates can possibly be transported using a continuous furnace with heating elements arranged along its travel path. The various heating elements can be set to different temperatures, for example, to implement different functionalities such as pre-drying, crystallization, etc.
[0075] In order to ultimately produce a solar cell 29 with the perovskite layer 1 formed in this way, in a fourth step (see Fig. 1 (d)) electrical contacts 31 in the form of an electrical back contact 39 and an electrical front contact 41 are produced, which electrically contact the perovskite layer 1 on opposite sides. In the simplified example, the back contact 39 can be applied to a side of the carrier substrate 3 opposite the perovskite layer 1 and electrically connected to the previously produced conductive layer 37 (not shown). Alternatively, and most preferably for practical applications, a back contact 39 can be formed which directly engages the conductive layer 37 located between the carrier substrate 3 and the perovskite layer 1. The back contact 39 can be provided, for example, in the form of a metal layer.The front contact 41 can be provided in the form of a plurality of thin, finger-like metal II contacts. Alternatively or additionally, the front contact 41 can be formed using an electrically conductive, transparent layer. Overall, a solar cell 29 in the form of a perovskite solar cell can be formed in this way. The side facing the sun can also be the side covered with the glass substrate. In this case, the metal layer 41 can act as a back contact and can possibly be formed over the entire surface.
[0076] Alternatively, the carrier substrate 3 can be formed from a pre-processed first solar cell 33 instead of a glass substrate. For example, this first solar cell 33 can be an efficient wafer-based silicon solar cell. The perovskite layer 1 can then be created on a front surface of this first solar cell 33, thereby forming a second solar cell 35. The two solar cells 33, 35 are electrically connected to one another via the conductive layer 37 formed between them and can thus form a solar cell 29 in the form of a tandem solar cell.
[0077] It should be noted that both the process steps and the resulting structures have been presented and described in a highly simplified manner. In a real implementation, additional process steps may be used and / or additional structures may be created, for example, in the form of additional layers, electrodes, or the like. Fig. 2 illustrates details of the transfer of the solution 9 to the carrier substrate 3 using the roller 11.
[0078] The solution 9 is continuously applied to the roller 11 at an upper first position 21 by means of the feed device 45. The roller 11 is designed as a sponge roller and has a solid roller core 47 surrounded by a sponge layer 49 made of absorbent material 17, such as porous polyurethane. The solution 9 is thus at least partially absorbed into the sponge layer 49 and moved along with the rotating roller 11.
[0079] At a lower second position 23, the roller 11 touches the carrier substrate 3 together with the first perovskite precursor layer 5 already deposited thereon. The roller 11 is pressed at least slightly against the carrier substrate 3, so that a part of the solution 9 absorbed therein is pressed out of the sponge layer 49 and transferred to the upper surface of the first perovskite precursor layer 5.
[0080] The roller 11 and the carrier substrate 3 are moved relative to one another, for example, by moving the carrier substrate 3 beneath the roller 11 using a conveyor device 51, and the roller 11 rolling along the upper surface of the perovskite precursor layer 5. In the example shown, the conveyor device 51 is configured with multiple conveyor rollers 59. Alternatively, other types of conveyor devices 51 can also be used, for example, a conveyor belt. Due to the relative movement between the roller 11 and the carrier substrate 3, the solution 9 emerging from the roller 11 forms the solution film 13 on the surface of the first perovskite precursor layer 5.
[0081] In order to be able to influence the amount of transferred solution 9 or the thickness of the solution film 13, a squeezing device 25 is provided at a third position 53. The third position 53 is located in the circumferential direction between the first position 21 and the second position 23. In the example shown, the squeezing device 25 is designed as a fixed roller and can also be referred to as a squeeze roller. The squeezing device 25 presses locally on the sponge layer 49 so that a portion of the solution 9 absorbed therein is squeezed out of it and thus does not reach a fourth position 55 below the squeezing device 25 and ultimately to the second position 23. Accordingly, the squeezing device 25 and in particular by adjusting a contact force or a contact pressure of this squeezing device 25 can be used to control the degree of saturation of the sponge roller.This ultimately allows the amount of solution 9 deposited onto the first perovskite precursor layer 5 to be controlled. Additionally, a suction device 27 is provided at a fifth position 57 between the first position 21 and the third position 53, by means of which an excess of solution 9 applied to the roller 11 can be sucked off.
[0082] Finally, it should be noted that terms such as "having," "comprising," etc., do not exclude other elements or steps, and terms such as "a" or "an" do not exclude a plurality. Furthermore, it should be noted that features or steps described with reference to one of the above embodiments may also be used in combination with other features or steps of other embodiments described above. Reference signs in the claims are not to be considered as limitations.
[0083] LIST OF REFERENCE SYMBOLS
[0084] I Perovskite layer
[0085] 3 Carrier substrate
[0086] 5 first perovskite precursor layer
[0087] 7 second perovskite precursor layer
[0088] 9 Solution
[0089] II Role
[0090] 13 Solution film
[0091] 15 Outer peripheral surface
[0092] 17 absorbent material
[0093] 21 first position
[0094] 23 second position
[0095] 25 Squeezing device
[0096] 27 Suction device
[0097] 29 solar cells
[0098] 31 electrical contacts
[0099] 33 first solar cell
[0100] 35 second solar cell
[0101] 37 Conductive layer
[0102] 39 electrical return contact
[0103] 41 electrical front contact
[0104] 43 stokers
[0105] 45 Feeding device
[0106] 47 roll core
[0107] 49 sponge layer
[0108] 51 conveyor system
[0109] 53 third position fourth position fifth position conveyor roller
Claims
AMENDED CLAIMS received by the International Bureau on 14 November 2024 (14.11.2024) 1. A method for forming a perovskite layer (1) on a carrier substrate (3), comprising: Providing the carrier substrate (3) coated with a first perovskite precursor layer (5) made of a first perovskite precursor, coating the first perovskite precursor layer (5) on the carrier substrate (3) with a second perovskite precursor layer (7) by - applying an aqueous solution (9) containing an inorganic second perovskite precursor forming the second perovskite precursor layer (7) to a roll (11), wherein the roll (11) is provided with absorbent, porous material (17) at least on an outer peripheral surface (15), and - transferring the solution (9) as a solution film (13), which forms the second perovskite precursor layer (7), to the first perovskite precursor layer (5) by rolling the roll (11) along the first perovskite precursor layer (5), and Heating the first perovskite precursor layer (5) together with the solution film (13) above a predetermined reaction temperature limit to initiate a chemical reaction between the first perovskite precursor and the second perovskite precursor.
2. Method according to one of the preceding claims, wherein the solution (9) contains only water and the second perovskite precursor. AMENDED SHEET (ARTICLE 19) 3. The method of claim 1 or 2, wherein the second perovskite precursor is a cesium halide salt.
4. A process according to any one of the preceding claims, wherein the first perovskite precursor is inorganic.
5. The method of claim 4, wherein the first perovskite precursor is a lead halide salt.
6. Method according to one of the preceding claims, wherein the roller (11) is formed with a polymer material.
7. Method according to one of the preceding claims, wherein the solution (9) is applied to the roller (11) at a first position (21) which is spaced from a second position (23) at which the roller (11) contacts the first perovskite precursor layer (5), and wherein in the circumferential direction between the first position (21) and the second position (23) a pressing device (25) is pressed against an outer circumferential surface (15) of the roller (11) in such a way that an amount of solution (9) which is carried along by the roller (11) during the rolling and is applied to the first perovskite precursor layer (5) is adjustable.
8. Method according to one of the preceding claims, wherein an excess of solution (9) applied to the roll (11) is sucked off the roll (11) by means of a suction device (27).
9. A method for manufacturing a solar cell (29), comprising Forming a perovskite layer (1) on a surface of a carrier substrate (3) which is previously coated with a first perovskite precursor layer (5) AMENDED SHEET (ARTICLE 19) by means of the method according to one of the preceding claims, and forming electrical contacts (31) for discharging electrical charge carriers from the perovskite layer (1).
10. The method according to one of the preceding claims, wherein the carrier substrate (3) comprises a first solar cell (33) and wherein the perovskite layer (1) is formed together with the electrical contacts (31) as a second solar cell (35). AMENDED SHEET (ARTICLE 19)