Method for producing a layer composed of perovskite, layer composed of perovskite and use of the layer composed of perovskite

Abstract

The invention relates to a method for producing a layer composed of perovskite , the perovskite being an organic-inorganic and / or a fully inorganic perovskite. The invention further relates to a layer that is composed of perovskite. The invention further relates to uses of the layer composed of perovskite inter alia as a light-absorbing layer in a photovoltaic cell.

Description

[0001] Friedrich-Alexander University Erlangen-Nuremberg, public corporation,

[0002] Schloßplatz 4, 91054 Erlangen, Germany

[0003] Method for producing a perovskite layer, perovskite layer and use of the perovskite layer

[0004] The invention relates to a method for producing a perovskite layer. The perovskite is an organic-inorganic, i.e., hybrid, and / or a completely inorganic perovskite. Furthermore, the invention relates to a perovskite layer. Furthermore, the invention relates to various uses of the perovskite layer.

[0005] Wet-chemical processes for producing hybrid perovskite layers are known in the state of the art. Examples of such wet-chemical processes include blade coating, spin coating, drop casting, dip coating, spray coating, slot-die coating, and inkjet printing.

[0006] Another approach involves depositing a material as a precursor and then converting it into the desired perovskite in one- or two-step processes (vapor- or solution-assisted).

[0007] The known processes are simple and quick to perform. However, they are limited in terms of precise control of layer thickness, especially for large-area or non-planar substrates, and in terms of scalability. Consequently, the imperfect reproducibility, homogeneity, and lack of thickness control of hybrid perovskite layers remain a major challenge.

[0008] The object of the present invention is to eliminate the disadvantages of the prior art. In particular, a method for producing a perovskite layer is to be provided that is simple, inexpensive, highly reproducible, and scalable, with which the layer thickness of the perovskite layer can be precisely controlled, with which the layer thickness of the perovskite layer can be adjusted, in particular, to within a few nanometers, and with which a homogeneous, continuous, conformal, and stable perovskite layer can be produced. Furthermore, a homogeneous, continuous, conformal, and stable perovskite layer is to be provided. Furthermore, various uses of the perovskite layer are to be specified.

[0009] According to the invention, this object is achieved by a method according to the subject matter of claim 1, by a layer of perovskite according to the subject matter of claim 19, and by uses according to the subject matter of claim 25. Advantageous embodiments of the invention are specified in the dependent claims.

[0010] According to the invention, a method for producing a layer of perovskite is claimed. The perovskite is an organic-inorganic and / or a completely inorganic perovskite. An organic-inorganic perovskite is also called a hybrid perovskite. The perovskite or the layer of perovskite preferably has a composition ABX3 or a composition A2BX4 and / or a composition

[0011] A2(MA)ni BnXßn+i or A2(FA) n -i BnXßn+i or a composition A3B2X9. The components A, B, X, MA, and FA are discussed in more detail below.

[0012] The method comprises the following steps, preferably in the following order: a) Providing a substrate in a reaction chamber, wherein the substrate has a substrate surface, b) Conveying a first solution into the reaction chamber, wherein the first solution is formed from a first precursor and a first solvent, wherein the first precursor reacts with the substrate surface and is deposited on the substrate, and wherein preferably a residual portion of the first precursor and / or reaction by-products remains / remain in the first solution, c) Conveying a first rinsing solvent into the reaction chamber, wherein the portion of the first precursor preferably remaining in the first solution and / or the remaining reaction by-products is / are completely or substantially completely removed from the reaction chamber, d) Conveying a second solution into the reaction chamber,wherein the second solution is formed from a second precursor and a second solvent, wherein the second precursor is reacted with the last solvent at the,

[0013] reacts with a precursor chemically bound to the substrate surface and is deposited on the substrate, wherein preferably a residual portion of the second precursor and / or reaction by-products remains / remain in the second solution, e) conveying a second rinsing solvent into the reaction space, wherein the portion of the second precursor preferably remaining in the second solution and / or the remaining reaction by-products is / are completely or essentially completely removed from the reaction space, f) repeating steps b) to e), preferably repeating steps b) to e several times, wherein the first precursor in step b) preferably does not react with the substrate surface, but reacts with the precursor last chemically bound to the substrate surface.

[0014] The first solvent comprises at least 99% aprotic solvent and / or an aprotic solvent mixture. The aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.5. Preferably, the aprotic solvent and / or the aprotic solvent mixture has / have a coordination ability index of -10 to -0.5, particularly preferably of -4 to -0.5.

[0015] The first solvent is preferably aprotic.

[0016] The second solvent comprises at least 99% aprotic solvent and / or an aprotic solvent mixture. The aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.5. Preferably, the aprotic solvent and / or the aprotic solvent mixture has / have a coordination ability index of -10 to -0.5, particularly preferably of -4 to -0.5. The second solvent is preferably aprotic.

[0017] According to the invention, the perovskite layer is formed by a chemical bonding, occurring in step d), of the second precursor with the precursor immediately previously chemically bonded to the substrate surface. The precursor immediately previously chemically bonded to the substrate surface is preferably the first precursor. Therefore, the perovskite layer is preferably formed by the chemical bonding, occurring in step d), of the second precursor with the first precursor immediately previously chemically bonded to the substrate surface.

[0018] The chemical bonding of the second precursor can occur exclusively with the precursor immediately previously chemically bonded to the substrate surface, preferably with the first precursor immediately previously chemically bonded to the substrate surface. Alternatively, the chemical bonding of the second precursor can occur with several precursors immediately previously chemically bonded to the substrate surface and / or with the substrate surface. Furthermore, the chemical bonding of the second precursor can occur with the precursor immediately previously chemically bonded to the substrate surface, preferably with the first precursor immediately previously chemically bonded to the substrate surface, and with the substrate surface.

[0019] The perovskite layer can be formed by the chemical bonding of the second precursor in step d) exclusively with the first precursor that was immediately previously chemically bonded to the substrate surface. Alternatively, the perovskite layer can be formed by the chemical bonding of the second precursor in step d) with several precursors that were immediately previously chemically bonded to the substrate surface and / or with the substrate surface. Furthermore, it is possible for the perovskite layer to be formed by the chemical bonding of the second precursor in step d) with the precursor that was immediately previously chemically bonded to the substrate surface, preferably with the first precursor that was immediately previously chemically bonded to the substrate surface, and with the substrate surface.

[0020] If steps b) to e) are repeated several times according to step f), a layer of perovskite is formed in each cycle, more precisely a monolayer of the perovskite layer.

[0021] The reaction chamber is preferably formed in a reaction vessel. The reaction vessel is preferably closed. The reaction vessel can be, for example, a microfluidic reactor. However, the reaction chamber and / or the reaction vessel can also be open to the environment.

[0022] The reaction chamber and / or the reaction vessel are preferably located in an inert atmosphere (e.g., N2 and / or Ar). This advantageously prevents contact of the precursors used and / or the resulting perovskite layer with air.

[0023] In step b), the first precursor reacts with the substrate surface preferably in a self-limiting surface reaction.

[0024] A self-limiting surface reaction is understood to be a chemical reaction in which only a limited number of binding partners for a specific chemical substance are available on a surface. After chemical bonds have been formed with each of these binding partners, advantageously no further chemical reactions can be entered into for the specific chemical substance. A self-limiting surface reaction, in the context of the present application, is understood in particular to be a chemical reaction on a surface of a limited size where a limited number of reaction partners (e.g., reactive and / or functional surface groups) are available.

[0025] In the reaction described in step b), a chemical bond is formed between the substrate, e.g., reactive groups on the substrate surface, and the first precursor. Starting in the second cycle, the first precursor in step b) preferably reacts with the second precursor that was last chemically bonded to the substrate surface, particularly in a self-limiting surface reaction. In this reaction, a chemical bond is formed between the second precursor and the first precursor, preferably a chemical bond formed exclusively between the second precursor and the first precursor.

[0026] In step b), at least part of the substrate surface is brought into contact with the first solution, preferably the entire substrate surface is brought into contact with the first solution.

[0027] In step c), any excess of first precursor is removed from the reaction space. This means that any remaining, non-chemically bound first precursor is removed from the reaction space. Upon completion of step c), preferably only chemically bound first precursor remains in the reaction space. The first precursor remaining in the reaction space is preferably chemically bound directly to the substrate, i.e., directly to the substrate surface, and / or (in the case of a repetition of step b) according to step f)) directly to the last chemically bound second precursor. In step d), the second precursor reacts with the last chemically bound precursor to the substrate surface, preferably in a self-limiting surface reaction.In particular, in step d), the second precursor reacts with the last chemically bound first precursor on the substrate surface in a self-limiting surface reaction.

[0028] In step d), the second precursor preferably reacts exclusively with the precursor last chemically bound to the substrate surface, preferably in a self-limiting surface reaction. In particular, in step d), the second precursor reacts exclusively with the first precursor last chemically bound to the substrate surface, preferably in a self-limiting surface reaction. Preferably, the binding partners available on the substrate surface are already completely saturated by the first precursor. Alternatively, in step d), the second precursor can react with several precursors immediately previously chemically bound to the substrate surface and / or with the substrate surface, preferably in a self-limiting surface reaction.For example, 99% of the binding partners available on the substrate surface are already saturated by the first precursor, so that only 1% of the binding partners available on the substrate surface can react with the second precursor in step d).

[0029] As already explained above, the second precursor reacts with the last precursor chemically bonded to the substrate surface, in particular with the first precursor, to form perovskite, i.e. the layer of perovskite.

[0030] In the reaction described in step d), a chemical bond is formed between the last precursor chemically bonded to the substrate surface and the second precursor. In particular, in the reaction described in step d), a chemical bond is formed between the last precursor chemically bonded to the substrate surface and the second precursor.

[0031] Preferably, in the reaction described in step d), a chemical bond is formed exclusively between the precursor last chemically bonded to the substrate surface and the second precursor. In particular, in the reaction described in step d), a chemical bond is formed exclusively between the first precursor last chemically bonded to the substrate surface and the second precursor.

[0032] In step d), at least a portion of the substrate surface is brought into contact with the second solution; preferably, the entire substrate surface is brought into contact with the second solution. The first precursor has already been deposited on the substrate surface, and (in the case of one or more repetitions according to step f)), a layer of perovskite has preferably already been deposited.

[0033] In step e), any excess of second precursor is removed from the reaction chamber. This means that any remaining, non-chemically bound second precursor is removed from the reaction chamber. Upon completion of step e), preferably only chemically bound second precursor remains in the reaction chamber. In particular, the second precursor preferably remains exclusively in the perovskite layer deposited on the substrate surface. The perovskite layer is chemically bonded to the substrate surface.

[0034] By providing steps c) and e) for flushing the reaction chamber, the first and second solutions preferably remain spatially separated from one another throughout the entire process according to the invention. In addition, the first and second solutions are preferably stored in different containers. This advantageously prevents uncontrollable direct reactions between the two solutions and instead advantageously enables surface reactions between the precursors or between one of the precursors and the substrate on the substrate surface of the substrate located in the reaction chamber.

[0035] The provision of steps c) and e) for purging the reaction space advantageously enables control over the chemical reactions entered into by the first and / or second precursor and thus control over the growth of the perovskite layer and over the layer thickness of the perovskite layer.

[0036] In step f), steps b) to e) are preferably repeated in this order. In particular, in step f), steps b) to e) are preferably repeated several times in this order.

[0037] According to step f), the first precursor reacts in step b) preferably exclusively with the precursor last chemically bound to the substrate surface, preferably in a self-limiting surface reaction. Alternatively, the first precursor according to step f) can react in step b) with several precursors immediately previously chemically bound to the substrate surface and / or with the substrate surface.

[0038] In other words, the chemical bonding of the first precursor can occur exclusively directly with the precursor that was immediately previously chemically bound to the substrate surface. Alternatively, the chemical bonding of the first precursor can occur directly with a plurality of precursors that were immediately previously chemically bound to the substrate surface and / or directly with the substrate surface. In particular, the first precursor according to step f) reacts in step b) preferably with the second precursor that was last chemically bound to the substrate surface, preferably in a self-limiting surface reaction. The first precursor preferably reacts exclusively with the second precursor that was last chemically bound to the substrate surface. Alternatively, the first precursor according to step f) can react in step b) with a plurality of precursors that were immediately previously chemically bound to the substrate surface and / or with the substrate surface.

[0039] For the purposes of this application, the term "cycle" refers precisely to one run through the process steps for providing each individual precursor and subsequent rinsing. Accordingly, each repetition of steps b) to e) according to step f) forms a cycle. A cycle comprises steps b) to e), preferably in this order. If exactly two precursors are provided, a cycle preferably consists of steps b) to e), preferably in this order. If at least three precursors are provided, a cycle comprises steps b), c), g), h), d) and e), preferably in this order. Steps g) and h) are defined further down in this application. If at least four precursors are provided, steps g) and h) are repeated accordingly within a cycle.

[0040] Preferably, steps b) to e) are repeated according to step f) until the perovskite layer has a predetermined thickness. The layer thickness is preferably 0.5 to 500 nm, preferably 0.5 to 200 nm, more preferably 0.5 to 100 nm, particularly preferably 0.5 to 50 nm, and most preferably 0.5 to 10 nm.

[0041] Steps b) to e) are preferably repeated 1 to 500 times, preferably 5 to 200 times, more preferably 10 to 100 times, even more preferably 20 to 100 times, particularly preferably 20 to 70 times according to step f). The process can be terminated optionally immediately after a final performance of step b), after a final performance of step c), after a final performance of step d), or after a final performance of step e);

[0042] Preferably, the method is terminated immediately after a final execution of step c) or after a final execution of step e). Preferably, therefore, steps b) to e) or b) and c) are repeated in the last cycle.

[0043] The process according to the invention is preferably carried out as atomic layer deposition (ALD) from the liquid phase. This process is also known as solution atomic layer deposition (abbreviated to "solution ALD" or "sALD").

[0044] Preferably, the chemical bond between the perovskite layer and the substrate surface, i.e., the substrate, is maintained throughout the entire process according to the invention. Preferably, the perovskite layer remains chemically bonded to the substrate surface, i.e., the substrate, even after completion of the process according to the invention.

[0045] In the context of the present application, the terms substrate and substrate surface are used interchangeably. For example, the statement that a substance reacts chemically with the substrate surface naturally also means that the substance reacts chemically with the substrate. For example, the statement that a substance is deposited on the substrate means that the substance is deposited on the substrate surface. In this case, however, it is also possible that the substance is deposited on a layer deposited on the substrate surface. For the purposes of the present application, a reaction is understood to mean a chemical reaction. The statement that one substance reacts with another substance means that the substance reacts chemically with the other substance. In addition to the chemical reaction, intermolecular interactions can also occur to a small extent.Intermolecular interactions are also called van der Waals interactions. In particular, a reaction is understood to be an irreversible chemical reaction, preferably one that is irreversible under the given conditions.

[0046] For the purposes of the present application, the statement that a substance is chemically bonded to another substance is understood to mean that the substance is directly or indirectly chemically bonded to the other substance. For example, for the purposes of the present application, a precursor that is chemically bonded to the last precursor chemically bonded to the substrate surface is also chemically bonded to the substrate surface. A "last precursor chemically bonded to the substrate surface" is preferably only indirectly chemically bonded to the substrate surface. Preferably, the "last precursor chemically bonded to the substrate surface" is directly chemically bonded to a precursor previously chemically bonded to the substrate surface.

[0047] The term "precursor" can also be referred to as "Vorstufe" and / or "Vorläufer" and / or "Vorstufemoleküle" (precursor molecules) according to German-language literature. A precursor is understood to mean a set of molecules and / or ionic compounds, preferably a set of similar molecules and / or similar ionic compounds. However, it is also possible for a precursor to comprise different types of molecules and / or different types of ionic compounds. For example, a precursor can comprise a set of similar molecules and a set of similar ionic compounds. As a further example, a precursor can comprise a set of one molecule with coordination character and a set of another molecule with coordination character. Furthermore, a precursor can comprise, for example, a set of one ionic compound and a set of another ionic compound. For the production of the perovskite MA3Sb2l9-xClx For example, a mixture of the ionic compound Sbh and the ionic compound SbCh can be used as the first precursor. (Alternatively, MA3Sb2l9-xCl can be used to produce the perovskite. x The ionic compounds Sbh and SbCh can also be provided separately from each other by two different precursor solutions, e.g., by the first solution and by a further solution.) Furthermore, a precursor can, for example, comprise a quantity of an ionic compound and a quantity of a molecule with coordination properties. The preceding definitions and possible configurations of a precursor apply in particular to the first, second, third, fourth, and / or further precursor.

[0048] In the context of this application, the term "organic radical" or the designation "organic radical R" is used generally to refer to a radical. Therefore, for example, an H atom and a halogen atom are also referred to as "organic radical" or "organic radical R."

[0049] The thickness of the perovskite layer can be measured ex-situ using spectroscopic ellipsometry and / or an atomic force microscope (AFM). From such a layer thickness measurement, a growth rate per cycle can be determined, given the number of cycles undergone to produce the perovskite layer. The layer thickness of the perovskite layer can also be measured in-situ during its production. The layer thickness of the perovskite layer is preferably measured using QCM (quartz crystal microbalance). Furthermore, the layer thickness of the perovskite layer can be determined during its production, given the growth rate per cycle and the number of cycles already undergone to produce the perovskite layer.

[0050] Preferably, the thickness of the perovskite layer can be precisely adjusted within the specified value range. Preferably, the thickness of the perovskite layer can be precisely adjusted to within 0.1 nm to 5 nm. Preferably, the thickness of the perovskite layer can be precisely adjusted to within 0.1 nm to 2 nm. Particularly preferably, the thickness of the perovskite layer can be precisely adjusted to within 0.1 nm to 1 nm. For example, the previously specified thickness of the perovskite layer is 9 nm. With an accuracy of 1 nm, the actual thickness of the perovskite layer is between 8.5 nm and 9.5 nm.

[0051] The layer thickness built up per cycle is preferably 0.1 A to 100 A, preferably 0.1 A to 50 A, particularly preferably 1 A to 20 A. Where A stands for Angstroms, 1 A = 0.1 nm. The layer thickness built up in the first cycles per cycle can be greater than the layer thickness built up in the subsequent cycles per cycle. For lead-containing perovskite, for example, CHsNHsPbh (methylammonium lead iodide), the layer thickness built up per cycle is, for example, 12 A, whereas the layer thickness built up in the first cycles per cycle is, for example, 20 A.

[0052] Alternatively, the layer thickness built up in the first cycles can be smaller than the layer thickness built up in subsequent cycles. Preferably, the layer thickness of the perovskite layer can be precisely adjusted to the layer thickness built up per cycle. In the example of lead-containing perovskite, the layer thickness of the perovskite layer can preferably be precisely adjusted to 1.2 nm.

[0053] The initial deposition of the first precursor according to step b) preferably takes place directly on the substrate, i.e., directly on the substrate surface. In particular, preferably no intermediate layer is applied to the substrate surface before the initial deposition of the first precursor according to step b).

[0054] For the purposes of this application, as in technical terminology, the term "perovskite" also includes perovskite-like structures. In particular, the term "perovskite" refers to a three-dimensional (3D) crystal structure. The three-dimensional (3D) crystal structure preferably has the composition ABX3. Furthermore, the term "perovskite" refers to a two-dimensional or quasi-two-dimensional crystal structure (2D or quasi-2D). The two-dimensional or quasi-two-dimensional crystal structure (2D or quasi-2D) preferably has the composition A2BX4 and / or the composition A2(MA) n -iB n X3n+i or A2(FA) n -i B n Xsn+i or the composition A3B2X9.

[0055] In a three-dimensional perovskite (3D) with a composition ABX3, A is preferably selected from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + , Rb +, Cs + or mixtures thereof. The organic radical R is preferably selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom. If several organic radicals are present, all organic radicals can be the same, or individual organic radicals can be different, or all organic radicals can be different. B is preferably selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof. X is preferably selected from a group comprising F; Cl, ​​Br, I; or mixtures thereof.

[0056] In a two-dimensional or quasi-two-dimensional perovskite (2D or quasi-2D) with a composition A2BX4, A is preferably selected from a group comprising organic ammonium, preferably [RNHs]+ and / or [R2NH2] + , Rb + , Cs + or mixtures thereof. The organic radical R is preferably selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom. B is preferably selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof. X is preferably selected from a group comprising F; Cl; Br; I; or mixtures thereof.

[0057] For a two-dimensional or quasi-two-dimensional perovskite (2D or quasi-2D) with a composition A2(MA) n -iB n X3n+i or A2(FA)ni BnXßn+i, A is preferably selected from a group comprising organic ammonium, preferably [RNHs] + and / or [R2NH2] Rb + , Cs +or mixtures thereof. The organic radical R is preferably selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom, or halogen atom. MA stands for the methylammonium cation, which has the composition [CHsNH3] + FA stands for the formamidinium cation, which has the composition [H2N-CH=NH2] + B is preferably selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof. X is preferably selected from a group comprising F; Cl; Br; I; or mixtures thereof.

[0058] In a two-dimensional or quasi-two-dimensional perovskite (2D or quasi-2D) with a composition A3B2X9, A is preferably selected from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + , Rb+ , Cs + or mixtures thereof. The organic radical R is preferably selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom. If several organic radicals are present, all organic radicals can be the same, or individual organic radicals can be different, or all organic radicals can be different. B is preferably selected from a group comprising As 3+ , Bi 3+ , Sb 3+ or mixtures thereof. X is preferably selected from a group comprising F, Cl, Br, I, or mixtures thereof.

[0059] The coordination ability index is defined in this application with regard to the coordination of a solvent or solvent mixture with transition metal complexes. For this purpose, the number of structures in which a solvent or solvent mixture is coordinated, semi-coordinated, or non-coordinated with any transition metal is taken into account. "Semi-coordinated" refers to those sparsely bonded structures in which bonds to a transition metal are formed at a distance shorter than the sum of the van der Waals radii. This results in the following formula for the coordination ability index a™ of a solvent or solvent mixture with transition metals, where c, s, and u are the number of structures in which the solvent or solvent mixture is coordinated, semi-coordinated, or non-coordinated with any transition metal.Values ​​for c, s, and u are available from the Cambridge Structural Database (CSD). a™ = log((c + s) / u).

[0060] The aprotic solvent and / or the aprotic solvent mixture contained in the solvent and / or first solvent and / or second solvent and / or further solvent therefore preferably has only weakly coordinating properties, preferably no coordinating properties. The aprotic solvent and / or the aprotic solvent mixture preferably has a coordination ability index a™ of at most -0.5 if the metal cation B contained in the perovskite structure contains at least one p- or d-block metal, semimetal, or transition metal. The aprotic solvent and / or the aprotic solvent mixture preferably has a coordination ability index a™ of at most -0.6 if the A contained in the perovskite structure contains at least one s-block alkali or alkaline earth metal. In this case, the coordination ability index a™ is preferably -10 to -0.6, particularly preferably -4 to -0.6.

[0061] As an alternative to the coordination ability index, the coordination ability percentage p can also be determined from c, s and u.

[0062] The definition of the coordination ability index a™ and the coordination ability percentage p is preferably carried out according to the scientific publication Alvarez, S.: “Coordinating Ability of Anions, Solvents, Amino Acids, and Gases towards Alkaline and Alkaline-Earth Elements, Transition Metals and Lanthanides” , Chem. Eur. J. 2020, 26, 4350 - 4377 (doi.org / 10.1002 / chem.201905453).

[0063] For the case of c + s = 0, the coordination ability index a™ is not defined. In this case, the coordination ability percentage p is 0.

[0064] A conversion between coordination ability index a™ and

[0065] Coordination ability percentage p is possible using the following formula: 100

[0066] P~ 1 + io-«™

[0067] With a coordination ability index a™ of -0.5, the coordination ability percentage p is up to 26.

[0068] The aprotic solvent according to the invention and / or the aprotic solvent mixture according to the invention can therefore, according to an alternative terminology, have a coordination ability percentage p of 0 to 26, preferably of 0.00000001 to 26, particularly preferably of 0.01 to 26.

[0069] The order of the first and second precursors can also be swapped. Thus, in step b), a second solution can be pumped into the reaction chamber, wherein the second solution is formed from a second precursor and a second solvent. In step c), a second rinsing solvent can be pumped into the reaction chamber. In step d), a first solution can be pumped into the reaction chamber, wherein the first solution is formed from a first precursor and a first solvent. In step e), a first rinsing solvent can be pumped into the reaction chamber. In this embodiment, in steps b), c), d), and e), all references to first, first, first, first are to be replaced by the corresponding designations second, second, second, second, second, and vice versa.In the steps g) and h) described below, the precursor last chemically bound to the substrate surface in this embodiment is preferably the second precursor.

[0070] The number of precursors is not limited to two. Any number of precursors can be used (in each cycle), in particular any number of different precursors can be used (in each cycle). For example, two, three, four, five or six precursors can be provided (in each cycle), in particular two, three, four, five or six different precursors can be used (in each cycle). Preferably, the same number of precursors is used in each cycle. Preferably, the same precursors are used in each cycle, in particular in the same order. Alternatively, the precursors can change between successive cycles. For example, the precursors can change alternately in successive cycles.In this example, a first cycle can have a first combination of precursors, in particular two, three, four, five or six precursors, while an immediately following second cycle can have a second combination of precursors that differs from the first combination, in particular two, three, four, five or six precursors. An immediately following third cycle can then again have the first combination, and an immediately following fourth cycle can then again have the second combination. This alternation between the first and second combination can be repeated until the desired layer thickness is reached. To produce a mixed metal cation perovskite, such as CH3(Pb,Sn)h, two precursors can be used in each cycle. The first precursor can remain the same in successive cycles, and the second precursor can be changed alternately.

[0071] The precursors used react to form a perovskite layer according to the invention. The precursors must therefore be selected such that the reactivity between the individual precursors leads to the desired perovskite as the product. Furthermore, the precursors must be selected such that components A, B, and X are present in the respective precursors used, particularly taking into account the possible precursor compositions specified below. In the case of the production of quasi-two-dimensional perovskite (2D or quasi-2D) with a composition A2(MA) n -iB n X3n+i or A2(FA) n -iB n X3n+i the precursors must be selected such that the components A, B and X and additionally the components MA or FA are present in the respective precursors used, in particular taking into account the possible precursor compositions given below.

[0072] As already described above, the chemical bonding of the second precursor can occur exclusively with the precursor immediately previously chemically bonded to the substrate surface; alternatively, the chemical bonding of the second precursor can occur with several precursors immediately previously chemically bonded to the substrate surface and / or with the substrate surface. If at least three precursors are used, the second precursor can intercalate between several precursors immediately previously chemically bonded to the substrate surface.

[0073] Accordingly, for example, a third solution comprising a third precursor and a third solvent and / or a third rinsing solvent can be used. Furthermore, for example, a fourth solution comprising a fourth precursor and a fourth solvent and / or a fourth rinsing solvent can be used. The third and fourth solvents can be the same. In particular, the third and fourth solvents can be the same as the first and / or second solvent. Alternatively, the third and fourth solvents can differ. Furthermore, the third and / or fourth solvents can differ from the first and / or second solvent. The third and fourth rinsing solvents can be the same. In particular, the third and fourth rinsing solvents can be the same as the first and / or second rinsing solvent. Alternatively, the third and fourth rinsing solvents can differ.Furthermore, the third and / or fourth rinsing solvent can differ from the first and / or second rinsing solvent. The respective solution, that is to say the first solution and / or the second solution and / or the third solution and / or the fourth solution and / or the further solution, and / or the respective rinsing solvent, that is to say the first rinsing solvent and / or the second rinsing solvent and / or the third rinsing solvent and / or the fourth rinsing solvent and / or the further rinsing solvent, is preferably conveyed into the reaction chamber at a flow rate in the range from 0.01 ml / min to 1000 ml / min, preferably in the range from 0.1 ml / min to 100 ml / min, particularly preferably in the range from 0.1 ml / min to 10 ml / min. The respective solutions and / or the respective solvents are preferably conveyed into the reaction chamber at the same flow rate.

[0074] The respective solution, that is to say the first solution and / or the second solution and / or the third solution and / or the fourth solution and / or the further solution, is preferably provided in the reaction chamber for a provision time in the range from 0.5 s to 10 min, preferably in the range from 0.5 s to 5 min, more preferably in the range from 0.5 s to 100 s, particularly preferably in the range from 0.5 s to 30 s, most particularly preferably in the range from 0.5 s to 20 s.

[0075] The respective rinsing solvent, i.e., the first rinsing solvent and / or the second rinsing solvent and / or the third rinsing solvent and / or the fourth rinsing solvent and / or the further rinsing solvent, is preferably provided in the reaction chamber for a rinsing time in the range of 10 s to 5 h, preferably in the range of 10 s to 1 h, particularly preferably in the range of 10 s to 10 min. The rinsing time preferably exceeds the immediately preceding provision time.

[0076] Successive perovskite layers, i.e., perovskite layers built up in successive cycles, are preferably composed of the same perovskite. By varying the first, second, and / or at least one further precursor in successive cycles, successive layers can be formed from different perovskites, wherein the perovskites are organic-inorganic, i.e., hybrid perovskites, and / or fully inorganic perovskites.

[0077] It is also possible for the steps of the method according to the invention to be carried out once or more than once. In particular, steps and sub-steps can be repeated. The preferred sequence of steps comprises at least the sequence of step a) - step b) - step c) - step d) - step e) - step f), wherein in particular further steps or sub-steps can be inserted between these steps. Preferably, no further steps or sub-steps are inserted between these steps. In particular, no further steps or sub-steps are inserted between steps b) to f). Preferably, further steps g) and h) are inserted once or more than once between step c) and step d) (see below). Apart from that, preferably no further steps or sub-steps are inserted between steps b) to f).

[0078] The process according to the invention results in direct deposition of the perovskite layer on the substrate. The deposition advantageously takes place in situ, i.e., exclusively in a reaction chamber. The perovskite layer is produced directly by the process according to the invention. Advantageously, no further processing of the layer is therefore required. In particular, no subsequent conversion and / or vapor conversion is required, such as, for example, the vapor conversion of initially deposited PbS to MAPI (methylammonium iodoplumbate) using vapors of MAI (methylammonium iodide) at high temperatures in the prior art.

[0079] Advantageously, the perovskite layer is deposited directly onto the substrate in the process according to the invention. Thus, advantageously, no intermediate layer or boundary layer is formed between the substrate and the perovskite layer due to the process.

[0080] The process according to the invention is based on self-limiting chemical reactions. The provision of the precursors is advantageously separated temporally and / or spatially. This advantageously prevents direct reaction between the (unbound) precursors. The provision of the precursors is advantageously carried out sequentially. Furthermore, the provision of the precursors is advantageously carried out cyclically.

[0081] The growth of the perovskite layer can occur according to various growth modes, such as: (1) Volmer-Weber (VW: "island formation"), (2) Frank-van der Merwe (FM: "layer-by-layer"), and / or (3) Stranski-Krastanov (SK: "layer-plus-island"). Mixtures of these growth modes can also occur. Preferably, the growth of the perovskite layer occurs layer by layer ("layer-by-layer growth"). The increase in the layer thickness of the perovskite layer preferably remains constant per cycle. The layer thickness of the perovskite layer therefore preferably shows a linear progression as a function of time and / or as a function of the number of cycles completed.

[0082] This advantageously results in the highest precision and control during the deposition of the perovskite layer. The thickness of the perovskite layer can therefore be precisely adjusted. The process according to the invention advantageously offers the highest precision and control even at extremely thin layer thicknesses in the range of 0.5 nm.

[0083] The process according to the invention is advantageously not limited to one material. Instead, a variety of different organic-inorganic perovskites, i.e., hybrid perovskites, and / or completely inorganic perovskites can be produced using the process according to the invention. The process according to the invention is advantageously simple, flexible, highly reproducible, gentle, scalable, energy-efficient, economical in precursor material, inexpensive, and inexpensive.

[0084] Furthermore, the rinsing solvent can be reused after filtration and / or distillation (with drying). Advantageously, 70 to 80% of the solvent can be recovered and reused in the process.

[0085] The perovskite layer is preferably homogeneous and / or continuous and / or conformal.

[0086] A homogeneous layer is understood to mean that the layer is evenly distributed across its planar extent. The perovskite layer is homogeneous over at least part of its planar extent. Preferably, the perovskite layer is homogeneous over a large planar extent. The perovskite layer can be homogeneous across its entire planar extent, except for recesses provided, for example, for masking. In particular, the perovskite layer is homogeneous across its entire planar extent.

[0087] A continuous layer is understood to be a self-contained layer. A continuous layer is preferably understood to be a self-contained layer without pores and / or without pinholes. The perovskite layer is preferably continuous in its planar extent and / or continuous in its construction direction arranged perpendicular to it. The perovskite layer is preferably continuous from a certain minimum layer thickness. The minimum layer thickness can be 50 nm. Preferably, the minimum layer thickness is 10 nm, particularly preferably 5 nm. A conformal coating is understood to mean that the coating reproduces the structure of the underlying surface. This applies in particular to a structured underlying surface. The conformal coating therefore has the same layer thickness at every position.

[0088] The perovskite layer is advantageously particularly stable. This is advantageously ensured by inter- and / or intramolecular interactions between the substrate and the perovskite layer, as well as inter- and / or intramolecular interactions within the perovskite layer.

[0089] The perovskite layer is advantageously transparent and / or semi-transparent.

[0090] Furthermore, the composition of the perovskite layer can advantageously be precisely adjusted. The stoichiometry of the individual components can be adjusted by adjusting the respective precursor concentrations and the respective precursor preparation times.

[0091] The flexibility during the process (e.g., the alternating change of one or more precursors in successive cycles as described above) advantageously allows the preparation of mixed (organic) cation / mixed metal cation / and / or mixed halide perovskites in a controlled manner.

[0092] Further advantageous embodiments of the invention are specified in the dependent claims.

[0093] According to an advantageous embodiment of the invention, the following

[0094] Steps are each carried out once or several times between step c) and step d), preferably in the following order.

[0095] Preferably, the following steps are carried out in this way in each cycle. g) Conveying a further solution into the reaction chamber, wherein the further solution is formed from a further precursor and a further solvent. The further precursor preferably reacts with the precursor last chemically bound to the substrate surface and is deposited on the substrate. In this case, a residual portion of the further precursor and / or reaction by-products preferably remains in the further solution. h) Conveying a further rinsing solvent into the reaction chamber, wherein the portion of the further precursor preferably remaining in the further solution and / or the remaining reaction by-products is / are completely or essentially completely removed from the reaction chamber.

[0096] The further solvent comprises at least 99% aprotic solvent and / or an aprotic solvent mixture. The aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.5. Preferably, the aprotic solvent and / or the aprotic solvent mixture has / have a coordination ability index of -10 to -0.5, particularly preferably of -4 to -0.5.

[0097] The additional solvent is preferably aprotic.

[0098] The phrase "between step c) and step d)" means that step c) has been completed, and step d) has not yet begun. Of course, each step is part of the same cycle. The phrase "between step c) and step d)" could, for example, be replaced by "after step c) and before step d)."

[0099] In step g), the further precursor reacts with the last precursor chemically bound to the substrate surface, preferably in a self-limiting surface reaction. In particular, in step g), the further precursor reacts with the last first precursor chemically bound to the substrate surface and / or with the last further precursor chemically bound to the substrate surface in a self-limiting surface reaction.

[0100] In step g), the further precursor preferably reacts exclusively with the precursor last chemically bound to the substrate surface, preferably in a self-limiting surface reaction. In particular, in step g), the further precursor reacts exclusively with the first precursor last chemically bound to the substrate surface or exclusively with the further precursor last chemically bound to the substrate surface, preferably in a self-limiting surface reaction. Preferably, the binding partners available on the substrate surface are already completely saturated by the first precursor and / or by at least one further precursor and / or by the second precursor.Alternatively, the additional precursor in step g) can react with several precursors chemically bound to the substrate surface immediately beforehand and / or with the substrate surface, preferably in a self-limiting surface reaction. For example, 99% of the binding partners available on the substrate surface are already saturated by the first precursor, so that a further 1% of the binding partners available on the substrate surface can react with the additional precursor in step g). In the reaction described in step g), a chemical bond is formed between the last precursor chemically bound to the substrate surface and the additional precursor.In particular, in the reaction described in step g), a chemical bond is formed between the further precursor and the first precursor last chemically bound to the substrate surface and / or the further precursor last chemically bound to the substrate surface.

[0101] The chemical bond of the further precursor can be formed in step g) exclusively with the precursor immediately previously chemically bound to the substrate surface, in particular exclusively with the first precursor last chemically bound to the substrate surface or exclusively with the further precursor last chemically bound to the substrate surface. Alternatively, the chemical bond of the further precursor can be formed in step g) directly with several precursors immediately previously chemically bound to the substrate surface and / or directly with the substrate surface. In this case, the further precursor can be intercalated between several precursors immediately previously chemically bound to the substrate surface.

[0102] In step g), at least a portion of the substrate surface is brought into contact with the further solution; preferably, the entire substrate surface is brought into contact with the further solution. The first precursor is already deposited on the substrate surface, optionally at least one further precursor is already deposited, and (in the case of one or more repetitions according to step f)), a layer of perovskite is preferably already deposited.

[0103] According to the invention, the perovskite layer is formed by a chemical bonding, occurring in step d), of the second precursor with the precursor immediately previously chemically bonded to the substrate surface. If steps g) and h) are provided, the precursor immediately previously chemically bonded to the substrate surface is the further precursor. Therefore, the perovskite layer is preferably formed by the chemical bonding, occurring in step d), of the second precursor with the further precursor immediately previously chemically bonded to the substrate surface.

[0104] The chemical bonding of the second precursor can occur exclusively with the further precursor that was immediately previously chemically bonded to the substrate surface. Alternatively, the chemical bonding of the second precursor can occur with several precursors that were immediately previously chemically bonded to the substrate surface, preferably with several further precursors that were immediately previously chemically bonded to the substrate surface, and / or with the substrate surface. Furthermore, the chemical bonding of the second precursor can occur with the further precursor that was immediately previously chemically bonded to the substrate surface and with the substrate surface.

[0105] The perovskite layer can be formed by the chemical bonding of the second precursor in step d) exclusively with the further precursor that was immediately previously chemically bonded to the substrate surface. Alternatively, the perovskite layer can be formed by the chemical bonding of the second precursor in step d) with a plurality of precursors that were immediately previously chemically bonded to the substrate surface, preferably with a plurality of further precursors that were immediately previously chemically bonded to the substrate surface, and / or with the substrate surface. Furthermore, it is possible for the perovskite layer to be formed by the chemical bonding of the second precursor in step d) with the further precursor that was immediately previously chemically bonded to the substrate surface and with the substrate surface. In step h), any excess of further precursor is removed from the reaction chamber.This means that any remaining, non-chemically bound precursor is removed from the reaction space. Upon completion of step h), preferably only chemically bound precursor remains in the reaction space. The remaining precursor in the reaction space is preferably chemically bonded directly to the last chemically bonded first precursor or chemically bonded directly to the last chemically bonded precursor.

[0106] The provision of steps c), e) and h) for purging the reaction space advantageously enables control over the chemical reactions entered into by the first and / or second and / or at least one further precursor and thus control over the growth of the perovskite layer and over the layer thickness of the perovskite layer.

[0107] Steps g) and h) can be performed any number of times between step c) and step d). In particular, steps g) and h) can be performed once, twice, three times, or four times between step c) and step d).

[0108] According to this advantageous embodiment of the invention, at least one additional precursor is used. Preferably, one additional precursor, or two additional precursors, or three additional precursors, or four additional precursors are used.

[0109] Preferably, the additional precursor used in each case differs. The first precursor, the second precursor, and the at least one additional precursor react to form the perovskite layer according to the invention. The precursors are to be selected such that the reactivity between the individual precursors leads to the desired perovskite as the product. Furthermore, the precursors are to be selected such that components A, B, and X are present in the respective precursors used, in particular taking into account the possible precursor compositions specified below. In the case of the production of quasi-two-dimensional perovskite (2D or quasi-2D) with a composition A2(MA) n -iB n X3n+i or A2(FA)n-iB nX3n+i the precursors must be selected such that the components A, B and X and additionally the components MA or FA are present in the respective precursors used, in particular taking into account the possible precursor compositions given below.

[0110] If multiple additional precursors are used, i.e., if steps g) and h) are carried out multiple times, the additional solvent used in each case can comprise the same aprotic solvent and / or the same aprotic solvent mixture to at least 99%. The additional solvents used in each case can be identical. However, one or more of the additional solvents used in each case can also have a different composition or compositions. The additional solvents used in each case can also each have a different composition.

[0111] Furthermore, the first solvent, the second solvent, and the at least one further solvent can each comprise the same aprotic solvent and / or the same aprotic solvent mixture to at least 99%. The first solvent, the second solvent, and the at least one further solvent can be identical. However, one or more of the group formed by the first solvent, the second solvent, and the at least one further solvent can also have a different composition or compositions. The first solvent, the second solvent, and the at least one further solvent can also each have a different composition.

[0112] Likewise, the additional rinsing solvent used in each case can comprise the same aprotic solvent and / or the same aprotic solvent mixture to at least 99%. The additional rinsing solvents used in each case can be identical. However, one or more of the additional rinsing solvents used in each case can also have a different composition or compositions. The additional rinsing solvents used in each case can also each have a different composition.

[0113] Furthermore, the first rinsing solvent, the second rinsing solvent, and the at least one further rinsing solvent can each comprise the same aprotic solvent and / or the same aprotic solvent mixture to at least 99%. The first rinsing solvent, the second rinsing solvent, and the at least one further rinsing solvent can be identical. However, one or more of the group formed by the first rinsing solvent, the second rinsing solvent, and the at least one further rinsing solvent can also have a different composition or compositions. The first rinsing solvent, the second rinsing solvent, and the at least one further rinsing solvent can also each have a different composition.

[0114] Furthermore, the first solvent and the first rinsing solvent can each comprise the same aprotic solvent and / or the same aprotic solvent mixture at least 99%. The first solvent and the first rinsing solvent can be identical. Alternatively, the first solvent and the first rinsing solvent can be different.

[0115] Furthermore, the second solvent and the second rinsing solvent can each comprise the same aprotic solvent and / or the same aprotic solvent mixture at least 99%. The second solvent and the second rinsing solvent can be identical. Alternatively, the second solvent and the second rinsing solvent can be different.

[0116] Furthermore, the at least one further solvent and the at least one further rinsing solvent can each comprise the same aprotic solvent and / or the same aprotic solvent mixture to at least 99%. The at least one further solvent and the at least one further rinsing solvent can be identical. Alternatively, the at least one further solvent and the at least one further rinsing solvent can be different.

[0117] The first solvent, the second solvent, the at least one further solvent, the first rinsing solvent, the second rinsing solvent, and the at least one further rinsing solvent can comprise nonpolar and / or polar hydrocarbon-containing solvents (alkanes, cyclic alkanes, aromatics, ethers, esters), nonpolar and polar halogenated carbon-based solvents, polar aprotic to protic solvents (alcohols, ketones, aldehydes, sulfoxides, amines, amides). The restrictions according to the invention naturally apply here. The first solvent, the second solvent, and the at least one further solvent each comprise at least 99% of an aprotic solvent and / or an aprotic solvent mixture. The aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.5.Protic solvents can therefore make up a maximum of 1% of the first solvent, the second solvent, or the at least one additional solvent. This applies, for example, to most alcohols, ketones, aldehydes, sulfoxides, amines, or amides because they are protic and polar. The same restrictions preferably apply to the first rinsing solvent, the second rinsing solvent, and / or the at least one additional rinsing solvent.

[0118] For example, at least one further solvent is chloroform and / or a mixture of chloroform and isopropanol with a maximum of 0.24 vol% isopropanol.

[0119] For example, at least one other rinsing solvent is chloroform.

[0120] The advantageous embodiment of the invention can advantageously be implemented particularly flexibly.

[0121] According to a further advantageous embodiment of the invention, the following step is carried out before step a) or simultaneously with step a) or between steps a) and b): i) Filling the reaction space with a solvent which comprises at least 99% an aprotic solvent and / or an aprotic solvent mixture, wherein the aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.5. Preferably, the aprotic solvent and / or the aprotic solvent mixture has / have a coordination ability index of -10 to -0.5, particularly preferably of -4 to -0.5. The solvent is preferably aprotic.

[0122] The solvent can include nonpolar and / or polar hydrocarbon-based solvents (alkanes, cyclic alkanes, aromatics, ethers, esters), nonpolar and polar halogenated carbon-based solvents, and polar aprotic and protic solvents (alcohols, ketones, aldehydes, sulfoxides, amines, amides). The restrictions mentioned in step i) apply. Protic solvents can therefore make up a maximum of 1% of the total solvent. This applies, for example, to most alcohols, ketones, aldehydes, sulfoxides, amines, or amides because they are protic and polar.

[0123] For example, the solvent is chloroform and / or a mixture of chloroform and isopropanol with a maximum of 0.24 vol% isopropanol.

[0124] In the process according to the invention, the reaction space is preferably filled with a solvent at all times. In particular, the reaction space is filled with a solvent during the implementation of steps a) to f), optionally including steps g) and h), or during the implementation of steps i) to f), optionally including steps g) and h). In other words, the substrate is preferably in a liquid atmosphere at all times. The substrate itself can be solid and / or flexible (e.g., formed from a polymer).

[0125] In particular, the substrate is in a liquid atmosphere during the implementation of steps a) to f), optionally including steps g) and h), or during the implementation of steps i) to f), optionally including steps g) and h). Thus, in the process according to the invention, an interface between the solid and liquid phases is preferably present at all times. Drying of the substrate is preferably not provided during the implementation of the process according to the invention, in particular during the implementation of steps a) to f), optionally including steps g) and h), or during the implementation of steps i) to f), optionally including steps g) and h). An exception to this may be drying of the substrate after the previously determined layer thickness of the perovskite layer has been reached at the end of the process according to the invention and / or after step f).

[0126] According to a further advantageous embodiment of the invention, the following step is carried out after step f), i.e. after the last cycle: j) drying the substrate coated with the layer of perovskite.

[0127] Drying of the substrate can be achieved by independent evaporation of the solvent. Alternatively or additionally, drying of the substrate can be achieved by exposure to an inert gas stream. The inert gas stream can comprise, for example, N2 and / or Ar. Alternatively or additionally, drying of the substrate can be achieved by heating the substrate. When drying the substrate by heating, the substrate is preferably heated to a temperature in the range of 40°C to 120°C, preferably to a temperature in the range of 40°C to 100°C, particularly preferably to a temperature in the range of 40°C to 50°C.

[0128] The substrate can be dried partially or completely in situ, i.e., in the reaction chamber. The substrate can be dried partially or completely after removal of the substrate from the reaction chamber (see step k) described below). The substrate can therefore first be dried partially in the reaction chamber and then completely after removal of the substrate from the reaction chamber. According to a further advantageous embodiment of the invention, the following step is carried out after step f), i.e., after the last cycle: k) Removal of the substrate coated with the perovskite layer from the reaction chamber.

[0129] Step k) may be carried out immediately after step f) and / or after step j) following step f).

[0130] It is possible for step k) to be performed immediately after step f) and before step j). Thus, the substrate can be removed from the reaction chamber after the perovskite layer has been completed and subsequently dried outside the reaction chamber.

[0131] The layer of perovskite and / or the substrate coated with the layer of perovskite is already the finished product of the process according to the invention.

[0132] The process according to the invention advantageously requires no further processing to produce the perovskite layer. The perovskite layer is produced directly by the process according to the invention. In particular, no subsequent conversion and / or vapor conversion is required, such as, for example, the prior art vapor conversion of initially deposited PbS to MAPI (methylammonium iodoplumbate) using vapors of MAI (methylammonium iodide) at high temperatures.

[0133] According to a further advantageous embodiment of the invention, the substrate is planar, porous and / or structured, preferably micro- and / or nanostructured, and / or powdered. Alternatively or additionally, the substrate is formed from an oxide and / or metal oxide and / or sulfide and / or metal sulfide and / or metallic material and / or carbonaceous material and / or polymeric material.

[0134] The substrate has at least one substrate surface. Preferably, the substrate has exactly one substrate surface on which the method according to the invention is carried out.

[0135] The substrate can be planar in some areas and / or porous in some areas and / or structured in some areas, preferably micro- and / or nanostructured in some areas, and / or powdery in some areas. For example, the substrate can be planar in one area of ​​the substrate surface and structured, preferably micro- and / or nanostructured, on the remaining substrate surface. Preferably, the substrate is planar over the entire substrate surface and / or porous over the entire substrate surface and / or structured, preferably micro- and / or nanostructured, over the entire substrate surface.

[0136] The substrate may have a coating with an oxide and / or metal oxide and / or sulfide and / or metal sulfide and / or metallic material and / or carbonaceous material and / or polymeric material.

[0137] The substrate can be rigid or flexible. The substrate can have any desired geometry. The substrate is preferably substantially or completely cuboid-shaped. Thus, the substrate preferably has a planar extension and a thickness (and / or height) perpendicular thereto. The thickness of the substrate is preferably significantly smaller than the planar extension of the substrate.

[0138] The substrate preferably has a planar extension in the range of 0.01 cm 2 up to 20000 cm 2 , preferably in the range of 100 cm 2 up to 10000 cm 2 , particularly preferably in the range of 1000 cm 2 up to 5000 cm 2 , on.

[0139] Preferably, the perovskite layer is formed over the entire substrate surface. Therefore, the perovskite layer preferably covers an area in the range of 0.01 cm 2 up to 20000 cm 2 , preferably in the range of 100 cm 2 up to 10000 cm 2 , particularly preferably in the range of 1000 cm 2 up to 5000 cm 2 .

[0140] The actual surface area of ​​structured or powdered substrates is preferably significantly larger than the planar extent of the substrate. Powdered substrates, in particular nanopowder substrates, preferably have an actual surface area of ​​50 m 2 / g up to 500 m 2 / g, for example from 200 m 2 / g on.

[0141] The substrate preferably has a thickness in the range of 0.01 cm to 5 cm, particularly preferably in the range of 0.1 cm to 1 cm.

[0142] If the substrate is structured, it preferably has a relief. The relief can have a comparatively large ratio between the depth of the relief and the width of the relief.

[0143] The substrate is made of tin oxide, for example. The substrate can be pretreated by exposing it to UV radiation and / or Os gas. This pretreatment can be followed by immersing the substrate in an aqueous KCl solution.

[0144] The perovskite layer is advantageously conformal with the substrate. The substrate can be planar and / or porous and / or structured, preferably micro- and / or nanostructured, and / or powdered.

[0145] A structured substrate, preferably a micro- and / or nanostructured substrate, or a powdered substrate, advantageously offers a significantly larger surface area compared to a planar substrate. This larger surface area allows more light to be absorbed even with a comparatively thin perovskite layer. The method according to the invention allows (as already described above) coating with extremely thin perovskite layers. This advantageously allows for material and cost savings.

[0146] According to a further advantageous embodiment of the invention, the first precursor is ionic or molecular with coordination character. In other words, the first precursor is ionic with molecular character of the counterion. The counterion can therefore have ligand character.

[0147] According to a further advantageous embodiment of the invention, the first precursor is dissolved in the first solution at a concentration of 0.1 to 100 mmol / L, preferably 0.1 to 50 mmol / L, particularly preferably 0.1 to 10 mmol / L, and most particularly preferably 0.1 to 5 mmol / L. For example, the first precursor is dissolved in the first solution at a concentration of 1 mmol / L. The unit mmol / L is to be read as millimoles per liter.

[0148] According to a further advantageous embodiment of the invention, the first precursor is used to produce a layer of three-dimensional (3D) perovskite with a composition ABX3 or to produce a layer of two-dimensional or quasi-two-dimensional (2D or quasi-2D) perovskite with a composition A2BX4 or to produce a layer of two-dimensional or quasi-two-dimensional (2D or quasi-2D) perovskite with a composition A2(MA) n -iB nX3n+i or with a composition A2(FA) n -iB n X3n+i is chosen so that the first precursor is a doubly positively charged cation B from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof, and negatively charged counterions and / or coordinating ligands G1 and G2 from a group comprising halide anion X as negatively charged counterion, carboxylate anion, alkoxides, beta-diketonate anion, amides, preferably organic amides, imides, silylamides, stannylamides, amidinates, guanidinates, pyrazolates, 1,4-diazabutadienes or mixtures thereof.

[0149] Two notes for clarification: The latter group refers to the entire phrase "negatively charged counterions and / or coordinating ligands G1 and G2." Likewise, the terms "G1 and G2" refer to the entire phrase "negatively charged counterions and / or coordinating ligands." These two notes also apply, of course, to the following use of the phrase "negatively charged counterions and / or coordinating ligands."

[0150] Preferably, the first precursor contains two negatively charged counterions and / or coordinating ligands G1 and G2 selected from the group just mentioned. The (preferably two) negatively charged counterions and / or coordinating ligands G1 and G2 are bound to B. The (preferably two) negatively charged counterions and / or coordinating ligands G1 and G2 can be the same or different. In abbreviation, G1 = G2 or G1 + G2 can apply.

[0151] The halide anion X is preferably selected from the group comprising F-, Cl-, Br, I-. The first precursor can also comprise a combination of different halide anions X. The first precursor can comprise similar ionic compounds comprising several different anions, including halide anions X. Examples are tin(II) diiodide, tin(II) acetate iodide, tin(II) iodide chloride, or

[0152] Lead(II) pivalate chloride. The first precursor can comprise various ionic compounds, each comprising a different anion X, for example, tin(II) diiodide and lead(II) pivalate chloride. A counterion can comprise multiple halide anions X, for example, two halide anions X. An example of this is SnCl (tin(II) chloride iodide). For example, the first precursor can be lead(II) pivalate. Lead(II) pivalate can also be written as lead(II)-[-O2CC(CH3)3]2 or Pb(Piv)2. Pivalate is a carboxylate anion (RCOO-).

[0153] To produce a Pb-based perovskite layer, the first precursor can be, for example, Pb(TMHD)2, i.e., lead(II) 2,2,6,6-tetramethyl-3,5-heptanedionate. TMHD belongs to the beta-diketonates.

[0154] To prepare a layer of Sb-based perovskite, the first precursor can be, for example, Sb(Piv)3, Sbh or SbCh.

[0155] To produce a layer of Sn-based perovskite, the first precursor can be, for example, Sn(Piv)2, Snh or Snk.

[0156] According to a further advantageous embodiment of the invention, the first precursor for producing a layer of two-dimensional or quasi-two-dimensional (2D or quasi-2D) perovskite with a composition A3B2X9 is selected such that the first precursor is a triply positively charged cation B from a group comprising As 3+ , Bi 3+ , Sb 3+ or mixtures thereof, and contains negatively charged counterions and / or coordinating ligands G1, G2 and G3 from a group comprising halide anion X as negatively charged counterion, carboxylate anion, alkoxides, beta-diketonate anion, (organic) amides, imides, silylamides, stannylamides, amidinates, guanidinates, pyrazolates, 1,4-diazabutadienes or mixtures thereof.

[0157] Preferably, the first precursor contains three negatively charged counterions and / or coordinating ligands G1, G2, and G3 from the group just mentioned. The (preferably three) negatively charged counterions and / or coordinating ligands G1, G2, and G3 are bound to B. The (preferably three) negatively charged counterions and / or coordinating ligands G1, G2, and G3 can be the same or at least partially different. In abbreviation, G1 = G2 = G3 or G1 + G2 = G3 or G1 = G2 + G3 or G1 + G2 + G3.

[0158] The halide anion X is preferably selected from the group comprising F-, Cl-, Br, I-. The first precursor can also comprise a combination of different halide anions X. The first precursor can comprise similar ionic compounds comprising several different anions, including halide anions X. Examples are tin(II) diiodide, tin(II) acetate iodide, tin(II) iodide chloride, or

[0159] Lead(II) iodide. The first precursor can comprise various ionic compounds, each comprising a different anion X, for example tin(II) diiodide and lead(II) iodide. A counterion can comprise several halide anions X, for example two halide anions X. An example of this is SnCl (tin(II) chloride iodide).

[0160] The first precursor can in particular contain mixtures of several metal cations from the above-mentioned group. The first precursor can comprise similar molecules or similar ionic compounds comprising several different metal cations B. The first precursor can comprise different molecules and / or different ionic compounds, each comprising a different metal cation B. For example, the first precursor can comprise an amount of one molecule with one metal cation B and an amount of another molecule with another metal cation B. The two amounts can, for example, form a 1:1 mixture, i.e., an equimolar mixture. Alternatively, the two amounts can form a non-equimolar mixture, for example, a 1:2 mixture, a 1:3 mixture, or a 1:4 mixture. The mixture preferably follows the desired stoichiometry of the solid product.An example of such a mixture is given below: the first precursor consists of a 1:1 mixture of Pb(Piv)2 and Sn(Piv)2. In this example, the first precursor can be dissolved in the first solution at a total concentration of 1 mmol / L.

[0161] In addition, MAI, for example, can be dissolved in the second solution as a second precursor at a concentration of 3 mM. This would result in the perovskite MAPbo.5Sno.5l3 being deposited as a perovskite with the composition ABX3. MAPiv (methylammonium pivalate) would be formed as a soluble byproduct.

[0162] In a variation of the above example, the components Pb 2+ and Sn 2+can also be provided in two different precursors. In this case, preferably at least three precursors are provided. For example, Pb(Piv)2 (step b)) as the first precursor, Sn(Piv)2 as a further precursor (step g)) and MAI as the second precursor (step d)). In a further example, Pb(Piv)2 can be provided as the first precursor (step b)), Snh as a further precursor (step g)) and MAI as the second precursor (step d)). In the latter example, the two substances Pb(Piv)2 and Snh are advantageously separated from one another in time and space by the procedure via two different precursors with an intermediate rinsing step (step c)), and this advantageously prevents Pb(Piv)2 + Snh from reacting directly to form Pbh, which is virtually insoluble in the solvent or solvent mixture used.

[0163] Advantageously, the Pbh or (Pb, Sn)h formed on the substrate surface in step g) reacts with the addition of MAI to the perovskite MAPbxSnyh, preferably with x = y = 0.5 in the above example of a 1:1 mixture.

[0164] Generally, the perovskite prepared according to the invention can contain a mixture of two or more metal cations B. A perovskite of composition ABX3 can be prepared according to the above example as MAPbo.5Sno.5l3.

[0165] Likewise, the first precursor may contain mixtures of several negatively charged counterions and / or coordinating ligands G1 and G2.

[0166] The four cases of different perovskite compositions summarized above are discussed individually below, giving more precise specifications:

[0167] To produce a layer of three-dimensional (3D) perovskite with a composition ABX3, the first precursor is preferably selected such that the first precursor is a doubly positively charged cation B from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof, and negatively charged counterions and / or coordinating ligands G1 and G2 from a group comprising halide anion X as negatively charged counterion, carboxylate anion (RCOO-, with organic radical R), alkoxides (RO _, with organic residue R), beta-diketonate anion (with two organic residues Ri and R2, where Ri = R2 or Ri + R2), amides and / or organic amides (R2N7 where Ri = R2 or Ri + R2), imides (RN-), silylamides ([RsSi^N-, with six organic residues R, where the six organic residues can be the same, or individual organic residues can be different, or all six organic residues can be different), stannylamides ([RsSn^N-, with six organic residues R, where all organic residues can be the same, or individual organic residues can be different, or all organic residues can be different), amidinates (with three organic residues Ri, R2, R3, where Ri = R2 = R3 or Ri + R2 = R3 or Ri = R2 + R3 or R2 + Ri = R3 or Ri + R2 + R3 + Ri), guanidinates (with four organic residues R, where the four organic residues can be the same, or individual organic residues can differ,or the four organic residues may be different), pyrazolates, 1,4-diazabutadienes (with four organic residues R, where the four organic residues may be the same, or individual organic residues may be different, or the four organic residues may be different) or mixtures thereof.

[0168] Preferably, the first precursor contains two negatively charged counterions and / or coordinating ligands G1 and G2 selected from the group just mentioned. The (preferably two) negatively charged counterions and / or coordinating ligands G1 and G2 are bound to B.

[0169] The (preferably two) negatively charged counterions and / or coordinating ligands G1 and G2 can be the same or different. In short, G1 = G2 or G1 + G2 can apply.

[0170] The organic radical R is preferably selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0171] The two organic radicals Ri and R2 are preferably each selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0172] The three organic radicals Ri, R2, R3 are preferably each selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0173] The four or six organic radicals R are each selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom. The halide anion X is preferably selected from the group comprising F-, Cl-, Br, I-. The first precursor can also comprise a combination of different halide anions X. The first precursor can comprise similar ionic compounds comprising several different anions including halide anions X. Examples of these are tin(II) diiodide, tin(II) acetate iodide, tin(II) iodide chloride or

[0174] Lead(II) pivalate chloride. The first precursor can comprise various ionic compounds, each comprising a different anion X, for example, tin(II) diiodide and lead(II) pivalate chloride. A counterion can comprise several halide anions X, for example, two halide anions X. An example of this is SnCl (tin(II) chloride iodide).

[0175] The explanations and definitions just given for organic residues R and halide anion X also apply to the different compositions of the perovskite in the following cases:

[0176] To produce a layer of two-dimensional or quasi-two-dimensional (2D or quasi-2D) perovskite with a composition A2BX4, the first precursor is preferably selected such that the first precursor is a doubly positively charged cation B from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co2+ , Zn 2+ , Fe 2+or mixtures thereof, and negatively charged counterions and / or coordinating ligands G1 and G2 from a group comprising halide anion X as negatively charged counterion, carboxylate anion (RCOO-, with organic radical R), alkoxides (RO-, with organic radical R), beta-diketonate anion (with two organic radicals Ri and R2, where Ri = R2 or Ri + R2), amides and / or organic amides (R2N-, where Ri = R2 or Ri + R2), imides (RN-), silylamides ([RsSi^N-, with six organic radicals R, where the six organic radicals can be the same, or individual organic radicals can be different, or all six organic radicals can be different), stannylamides ([RsSn^N-, with six organic radicals R, where all organic radicals can be the same, or individual organic radicals can be different, or all organic radicals can be different), amidinates (with three organic radicals Ri, R2, R3,where Ri = R2 = R3 or Ri + R2 = R3 or Ri = R2 + R3 or R2 + Ri = R3 or Ri + R2 + R3 + Ri), guanidinates (with four organic residues R, where the four organic residues can be the same, or individual organic residues can differ, or the four organic residues can be different), pyrazolates, 1,4-diazabutadienes (with four organic residues R, where the four organic residues can be the same, or individual organic residues can differ, or the four organic residues can be different) or mixtures thereof.

[0177] Preferably, the first precursor contains two negatively charged counterions and / or coordinating ligands G1 and G2 selected from the group just mentioned. The (preferably two) negatively charged counterions and / or coordinating ligands G1 and G2 are bound to B.

[0178] The (preferably two) negatively charged counterions and / or coordinating ligands G1 and G2 can be the same or different. In short, G1 = G2 or G1 + G2 can apply.

[0179] For the preparation of a layer of two-dimensional or quasi-two-dimensional (2D or quasi-2D) perovskite with a composition A2(MA)ni BnXßn+i or A2(FA) n -i B n X3n+i, the first precursor is preferably chosen such that the first precursor is a doubly positively charged cation B from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof, and (two) negatively charged counterions and / or coordinating ligands G1 and G2 from a group comprising halide anion X as negatively charged counterion, carboxylate anion (RCOO-, with organic radical R), alkoxides (RO _, with organic residue R), beta-diketonate anion (with two organic residues Ri and R2, where Ri = R2 or Ri + R2), amides and / or organic amides (R2N-, where Ri = R2 or Ri + R2), imides (RN _), silylamides ([RsSi^N-, with six organic residues R, where the six organic residues can be the same, or individual organic residues can be different, or all six organic residues can be different), stannylamides ([RsSn^N-, with six organic residues R, where all organic residues can be the same, or individual organic residues can be different, or all organic residues can be different), amidinates (with three organic residues Ri, R2, R3, where Ri = R2 = R3 or Ri + R2 = R3 or Ri = R2 + R3 or R2 + Ri = R3 or Ri + R2 + R3 + Ri), guanidinates (with four organic residues R, where the four organic residues can be the same, or individual organic residues can be different, or the four organic residues can be different), pyrazolates, 1,4-diazabutadienes (with four organic residues R, where the four organic residues can be the same, or individual organic residues can be different,or the four organic residues may be different) or mixtures thereof.

[0180] Preferably, the first precursor contains two negatively charged counterions and / or coordinating ligands G1 and G2 selected from the group just mentioned. The (preferably two) negatively charged counterions and / or coordinating ligands G1 and G2 are bound to B.

[0181] The (preferably two) negatively charged counterions and / or coordinating ligands G1 and G2 can be the same or different. In short, G1 = G2 or G1 + G2 can apply.

[0182] To produce a layer of two-dimensional or quasi-two-dimensional (2D or quasi-2D) perovskite with a composition A3B2X9, the first precursor is preferably selected such that the first precursor is a triply positively charged cation B from a group comprising As 3+ , Bi 3+ , Sb 3+or mixtures thereof, and (three) negatively charged counterions and / or coordinating ligands G1, G2 and G3 from a group comprising halide anion X as negatively charged counterion, carboxylate anion (RCOO-, with organic radical R), alkoxides (RO _, with organic residue R), beta-diketonate anion (with two organic residues Ri and R2, where Ri = R2 or Ri + R2), amides and / or organic amides (R2N-, where Ri = R2 or Ri + R2), imides (RN-), silylamides ([RsSi^N-, with six organic residues R, where the six organic residues can be the same, or individual organic residues can be different, or all six organic residues can be different), stannylamides ([RsSn^N-, with six organic residues R, where all organic residues can be the same, or individual organic residues can be different, or all organic residues can be different), amidinates (with three organic residues Ri, R2, R3, where Ri = R2 = R3 or Ri + R2 = R3 or Ri = R2 + R3 or R2 + Ri = R3 or Ri + R2 + R3 + Ri), guanidinates (with four organic residues R, where the four organic residues can be the same, or individual organic residues can differ,or the four organic residues may be different), pyrazolates, 1,4-diazabutadienes (with four organic residues R, where the four organic residues may be the same, or individual organic residues may be different, or the four organic residues may be different) or mixtures thereof.

[0183] Preferably, the first precursor contains three negatively charged counterions and / or coordinating ligands G1, G2, and G3 from the group just mentioned. The (preferably three) negatively charged counterions and / or coordinating ligands G1, G2, and G3 are bound to B.

[0184] The (preferably three) negatively charged counterions and / or coordinating ligands G1, G2, and G3 can be identical or at least partially different. In abbreviation, G1 = G2 = G3 or G1 + G2 = G3 or G1 = G2 + G3 or G1 + G2 + G3 can apply. According to a further advantageous embodiment of the invention, the second precursor is ionic or molecular with coordination character. In other words, the second precursor is ionic with the molecular character of the counterion. The counterion can therefore have ligand character.

[0185] According to a further advantageous embodiment of the invention, the second precursor is dissolved in the second solution at a concentration of 0.1 to 100 mmol / L, preferably 0.1 to 50 mmol / L, particularly preferably 0.1 to 10 mmol / L, and most preferably 0.1 to 5 mmol / L. For example, the second precursor is dissolved in the second solution at a concentration of 4 mmol / L. The unit mmol / L is to be read as millimoles per liter.

[0186] For example, the second precursor can be methylammonium iodide. Methylammonium iodide can also be denoted by the molecular formula [CHsNHs]! or by the abbreviation MAI.

[0187] In the same example, the first precursor can be lead(II) pivalate. Lead(II) pivalate can also be written as lead(II)-[-O2CC(CH3)3]2 or Pb(Piv)2.

[0188] The underlying chemical reaction is:

[0189] Pb(Piv)2+ 3 MAI MAPbh + 2 MAPiv,

[0190] The abbreviations used are explained below:

[0191] Pb(Piv)2= lead(II) pivalate,

[0192] MAI = Methylammonium iodide,

[0193] MAPbh = methylammonium lead(II) iodide, MAPiv = methylammonium pivalate. In this example, the reaction product is methylammonium iodoplumbate (MAPI). This means that the perovskite layer in this example is formed from methylammonium iodoplumbate (MAPI). In other words, the perovskite layer in this example is a layer of methylammonium iodoplumbate (MAPI).

[0194] Another example of the perovskite layer results from the deposition of the hybrid, bilayer, Sb-based perovskite MA3Sb2l9-xClx.

[0195] Other examples of the second precursor are tetramethylammonium iodide, tetraethylammonium iodide, tetrabutylammonium iodide, tetrabutylammonium bromide and tetraethylammonium chloride.

[0196] The process according to the invention preferably results in a combination of ionic reactants and an ionic product. The reactants are the precursors, i.e., the first precursor and / or the second precursor and / or the at least one further precursor are preferably ionic. The product is the perovskite or the perovskite layer. The perovskite is preferably ionic. However, as already mentioned above, the precursors can be ionic or molecular with coordination characteristics.

[0197] According to a further advantageous embodiment of the invention, the second precursor for producing a layer of three-dimensional (3D) perovskite with a composition ABX3 is selected such that the second precursor is a singly positively charged cation A from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + , Rb + , Cs +, or mixtures thereof, and a singly negatively charged counterion and / or a coordinating ligand G from a group comprising halide anion X as negatively charged counterion, carboxylate anion, beta-diketonates, or mixtures thereof, wherein the singly negatively charged counterion and / or the coordinating ligand G is bonded to A.

[0198] According to a further advantageous embodiment of the invention, the second precursor for producing a layer of two-dimensional or quasi-two-dimensional (2D or quasi-2D) perovskite with a composition A2BX4 is selected such that the second precursor is a singly positively charged cation A from a group comprising organic ammonium, preferably [RNH3] + and / or [R2NH2] + , Rb + , Cs +, or mixtures thereof, and a singly negatively charged counterion and / or a coordinating ligand G from a group comprising halide anion X as negatively charged counterion, carboxylate anion, beta-diketonates, or mixtures thereof, wherein the singly negatively charged counterion and / or the coordinating ligand G is bonded to A.

[0199] According to a further advantageous embodiment of the invention, the second precursor is used to produce a layer of two-dimensional or quasi-two-dimensional (2D or quasi-2D) perovskite with a composition A2(MA)ni BnXßn+i or A2(FA) n -i B n X3n+i is chosen so that the second precursor is a singly positively charged cation A from a group comprising organic ammonium, preferably [RNHs] + and / or [R2NH2] + , Rb + , Cs +, or mixtures thereof, contains a singly positively charged methylammonium cation MA or a singly positively charged formamidinium cation FA, and contains a singly negatively charged counterion and / or a coordinating ligand G from a group comprising halide anion X as negatively charged counterion, carboxylate anion, beta-diketonates, or mixtures thereof, wherein the singly negatively charged counterion and / or the coordinating ligand G is bonded to A.

[0200] According to a further advantageous embodiment of the invention, the second precursor for producing a layer of two-dimensional or quasi-two-dimensional (2D or quasi-2D) perovskite with a composition A3B2X9 is selected such that the second precursor is a singly positively charged cation A from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + , Rb + , Cs +, or mixtures thereof, and a singly negatively charged counterion and / or a coordinating ligand G from a group comprising halide anion X as negatively charged counterion, carboxylate anion, beta-diketonates, or mixtures thereof, wherein the singly negatively charged counterion and / or the coordinating ligand G is bonded to A.

[0201] The singly negatively charged counterion and / or the coordinating ligand G of the second precursor can therefore in particular be the halide anion X.

[0202] The halide anion X is preferably selected from the group comprising F-, Cl-, Br, I-. The first precursor can also comprise a combination of different halide anions X. The first precursor can comprise similar ionic compounds comprising several different anions, including halide anions X. Examples are tin(II) diiodide, tin(II) acetate iodide, tin(II) iodide chloride, or

[0203] Lead(II) iodide. The first precursor can comprise various ionic compounds, each comprising a different anion X, for example tin(II) diiodide and lead(II) iodide. A counterion can comprise several halide anions X, for example two halide anions X. An example of this is SnCl (tin(II) chloride iodide).

[0204] Preferably, the precursors, in particular the first precursor, the second precursor, and / or the at least one further precursor, provide the constituents of the perovskite to be produced in sufficient concentration. Preferably, the precursors, in particular the first precursor, the second precursor, and / or the at least one further precursor, provide the constituents of the perovskite to be produced in saturation. Particularly preferably, the precursors, in particular the first precursor, the second precursor, and / or the at least one further precursor, provide the constituents of the perovskite to be produced in the stoichiometrically required amount.

[0205] The number of halide anions X required for the composition of the perovskite is preferably provided by the first precursor and / or by the second precursor and / or by the at least one further precursor.

[0206] The four cases of different perovskite compositions just mentioned are discussed individually below, with more detailed specifications:

[0207] To produce a layer of three-dimensional (3D) perovskite with a composition ABX3, the second precursor is preferably selected such that the second precursor is a singly positively charged cation A from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + (each with an organic radical R, where in the presence of several organic radicals all organic radicals can be the same, or individual organic radicals can be different, or all organic radicals can be different, i.e. in the case of three organic radicals: Ri = R2 = R3 or Ri + R2 = R3 or Ri = R2 + Rs or R2 + Ri = R3 or Ri + R2 + R3 + Ri), Rb + , Cs +, or mixtures thereof, and a singly negatively charged counterion and / or a coordinating ligand G from a group comprising halide anion X as negatively charged counterion, carboxylate anion (RCOO-, with organic radical R), beta-diketonates (with two organic radicals Ri and R2, where Ri = R2 or Ri + R2) or mixtures thereof. The singly negatively charged counterion and / or the coordinating ligand G is bonded to A. The organic radical R is preferably selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0208] The two organic radicals Ri and R2 are preferably each selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0209] Three organic radicals Ri, R2, R3 are preferably each selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0210] The four organic radicals R are each selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0211] The halide anion X is preferably selected from the group comprising F-, Cl-, Br, I-. The first precursor can also comprise a combination of different halide anions X. The first precursor can comprise similar ionic compounds comprising several different anions, including halide anions X. Examples are tin(II) diiodide, tin(II) acetate iodide, tin(II) iodide chloride, or

[0212] Lead(II) iodide. The first precursor can comprise various ionic compounds, each comprising a different anion X, for example tin(II) diiodide and lead(II) iodide. A counterion can comprise several halide anions X, for example two halide anions X. An example of this is SnCl (tin(II) chloride iodide).

[0213] To produce a layer of two-dimensional or quasi-two-dimensional (2D or quasi-2D) perovskite with a composition A2BX4, the second precursor is preferably selected such that the second precursor is a singly positively charged cation A from a group comprising organic ammonium, preferably [RNHs] + and / or [R2NH2] + (with organic residue R), Rb + , Cs +, or mixtures thereof, and a singly negatively charged counterion and / or a coordinating ligand G from a group comprising halide anion X as negatively charged counterion, carboxylate anion (RCOO-, with organic radical R), beta-diketonates (with two organic radicals Ri and R2, where Ri = R2 or Ri + R2) or mixtures thereof. The singly negatively charged counterion and / or the coordinating ligand G is bonded to A.

[0214] The organic radical R is preferably selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0215] The two organic radicals Ri and R2 are preferably each selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0216] The halide anion X is preferably selected from the group comprising F-, Cl-, Br, I-. The first precursor can also comprise a combination of different halide anions X. The first precursor can comprise similar ionic compounds comprising several different anions, including halide anions X. Examples are tin(II) diiodide, tin(II) acetate iodide, tin(II) iodide chloride, or

[0217] Lead(II) iodide chloride. The first precursor can comprise various ionic compounds, each comprising a different anion X, for example tin(II) diiodide and lead(II) iodide chloride. A counterion can comprise several halide anions X, for example two halide anions X. An example of this is SnCl (tin(II) chloride iodide). To produce a layer of two-dimensional or quasi-two-dimensional (2D or quasi-2D) perovskite with a composition A2(MA)n+i BnXßn+i or A2(FA) n -i Bn X3n+i, the second precursor is preferably chosen such that the second precursor is a singly positively charged cation A from a group comprising organic ammonium, preferably [RNHs] + and / or [R2NH2] + (with organic residue R), Rb + , Cs + , or mixtures thereof, a singly positively charged methylammonium cation MA with the composition [CH3NH3] + or a singly positively charged formamidinium cation FA with the composition [H2N-CH=NH2] + and a singly negatively charged counterion and / or a coordinating ligand G from a group comprising halide anion X as negatively charged counterion, carboxylate anion (RCOO-, with organic radical R), beta-diketonates (with two organic radicals Ri and R2, where Ri = R2 or Ri + R2) or mixtures thereof. The singly negatively charged counterion and / or the coordinating ligand G is bound to A.

[0218] Where n is a natural number.

[0219] The organic radical R is preferably selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0220] The two organic radicals R1 and R2 are preferably each selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0221] The halide anion X is preferably selected from the group comprising F-, Cl-, Br, I-. The first precursor can also comprise a combination of different halide anions X. The first precursor can comprise similar ionic compounds comprising several different anions including halide anions X. Examples of these are tin(II) diiodide, tin(II) acetate iodide, tin(II) iodide chloride or lead(II) pivalate chloride. The first precursor can comprise different ionic compounds, each comprising a different anion X, for example tin(II) diiodide and lead(II) pivalate chloride. A counterion can comprise several halide anions X, for example two halide anions X. An example of this is SnClII (tin(II) chloride iodide).

[0222] To produce a layer of two-dimensional or quasi-two-dimensional perovskite (2D or quasi-2D) perovskite with a composition A3B2X9, the second precursor is preferably selected such that the second precursor is a singly positively charged cation A from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + (each with an organic radical R, where in the presence of several organic radicals all organic radicals can be the same, or individual organic radicals can be different, or all organic radicals can be different, i.e. in the case of three organic radicals: Ri = R2 = R3 or Ri + R2 = R3 or Ri = R2 + Rs or R2 + Ri = R3 or Ri + R2 + R3 + Ri), Rb + , Cs +, or mixtures thereof, and a singly negatively charged counterion and / or a coordinating ligand G from a group comprising halide anion X as negatively charged counterion, carboxylate anion (RCOO-, with organic radical R), beta-diketonates (with two organic radicals Ri and R2, where Ri = R2 or Ri + R2) or mixtures thereof. The singly negatively charged counterion and / or the coordinating ligand G is bonded to A.

[0223] The organic radical R is preferably selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0224] The two organic radicals R1 and R2 are preferably each selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, hydrogen atom, or halogen atom. Three organic radicals R1, R2, and R3 are preferably each selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, hydrogen atom, or halogen atom.

[0225] The four organic radicals R are each selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0226] The halide anion X is preferably selected from the group comprising F-, Cl-, Br, I-. The first precursor can also comprise a combination of different halide anions X. The first precursor can comprise similar ionic compounds comprising several different anions, including halide anions X. Examples are tin(II) diiodide, tin(II) acetate iodide, tin(II) iodide chloride, or

[0227] Lead(II) iodide. The first precursor can comprise various ionic compounds, each comprising a different anion X, for example tin(II) diiodide and lead(II) iodide. A counterion can comprise several halide anions X, for example two halide anions X. An example of this is SnCl (tin(II) chloride iodide).

[0228] The second precursor can, in particular, contain mixtures of several cations A from the respective above-mentioned groups. Accordingly, the perovskite produced according to the invention can contain a mixture of two or more cations A for A. Examples of these are a mixture of tetrabutylammonium iodide and tetrabutylammonium bromide or a mixture of tetraethylammonium iodide and tetraethylammonium chloride.

[0229] According to a further advantageous embodiment of the invention, the at least one further precursor is ionic or molecular with coordination characteristics. In other words, the at least one further precursor is ionic with the molecular character of the counterion. The counterion can therefore have ligand characteristics.

[0230] According to a further advantageous embodiment of the invention, the further precursor is dissolved in the further solution at a concentration of 0.1 to 100 mmol / L, preferably 0.1 to 50 mmol / L, particularly preferably 0.1 to 10 mmol / L, and most particularly preferably 0.1 to 5 mmol / L. The unit mmol / L is to be read as millimoles per liter.

[0231] According to a further advantageous embodiment of the invention, the first precursor, the second precursor, and preferably the at least one further precursor are selected such that they provide the components A, B, X, and optionally MA or FA of the perovskite layer to be formed. In the case of producing a layer of two-dimensional or quasi-two-dimensional (2D or quasi-2D) perovskite with a composition A2(MA) n -iB n X3n+i or A2(FA) n -i B n X3n+i provided by the mentioned precursors.

[0232] To produce a layer of three-dimensional (3D) perovskite with a composition ABX3, component A is selected from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + (each with organic residue R), Rb + , Cs + or mixtures thereof. Component B is a divalent metal cation. The divalent metal cation is preferably selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof. The component X is a halide anion. The halide anion X is preferably selected from the group comprising F, Cl, Br, I, or mixtures thereof.

[0233] When multiple organic radicals are present, all organic radicals can be identical, or individual organic radicals can be different, or all organic radicals can be different. The organic radical R is selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, hydrogen atom, or halogen atom.

[0234] The plurality of organic radicals R are selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0235] For the production of a layer of two-dimensional or quasi-two-dimensional perovskite (2D or quasi-2D) with a composition A2BX4, component A is selected from a group comprising organic ammonium, preferably [RNH3] + and / or [R2NH2] + (with organic residue R), Rb + , Cs +or mixtures thereof. Component B is a divalent metal cation. The divalent metal cation is preferably selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof. The component X is a halide anion. The halide anion X is preferably selected from the group comprising F _ , CI-, Br, I or mixtures thereof.

[0236] The organic radical R is selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0237] For the preparation of a layer of two-dimensional or quasi-two-dimensional perovskite (2D or quasi-2D) with a composition A2(MA)ni BnXßn+i or A2(FA) n -i B nX3n+i is component A from a group comprising organic ammonium, preferably [RNHs] + and / or [R2NH2] + (with organic residue R), Rb + , Cs + or mixtures thereof. The component MA is a methylammonium cation with the composition [CH3NH3] + or the component FA is a formamidinium cation with the composition [H2N-CH=NH2] + . Component B is a divalent metal cation. The divalent metal cation is preferably selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof. The component X is a halide anion. The halide anion X is preferably selected from the group comprising F-, Cl-, Br, F , or mixtures thereof.

[0238] The organic radical R is selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0239] To produce a layer of two-dimensional or quasi-two-dimensional perovskite (2D or quasi-2D) with a composition A3B2X9, component A is selected from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + (each with organic residue R), Rb + , Cs + or mixtures thereof. Component B is a trivalent metal cation. The trivalent metal cation is preferably selected from a group comprising As 3+ , Bi 3+ , Sb 3+ or mixtures thereof. The component X is a halide anion. The halide anion X is preferably selected from the group comprising F, Cl, Br, F, or mixtures thereof.

[0240] If several organic residues are present, all organic residues may be the same, or individual organic residues may be different, or all organic residues may be different.

[0241] The organic radical R is selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, hydrogen atom, or halogen atom. The plurality of organic radicals R are selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, hydrogen atom, or halogen atom.

[0242] According to a further advantageous embodiment of the invention, the first precursor, the second precursor and preferably the at least one further precursor are selected such that the first precursor, the second precursor and preferably the at least one further precursor react with one another to form the perovskite layer, wherein the perovskite layer is not soluble in the first, the second and preferably the at least one further solvent.

[0243] The precursors thus provide the components A, B, X, and optionally MA or FA. The precursors then react with each other to form the desired product (a perovskite layer), which is insoluble in the solvent used. Any reaction byproducts are preferably soluble in the solvent used. The solubility conditions in the respective solvent and / or solvent mixture and / or solvent mixtures are within the specified ranges.

[0244] Typically, in the process according to the invention, step c) begins with a precursor (first precursor) containing a metal cation B. The next precursor (second precursor) or the next precursors (second precursor and further or further precursors) then provide the components A and X (and optionally MA or FA) in the next steps. Deviating from this, the process according to the invention can begin in step c) with a precursor containing the components A and / or X and / or optionally MA or FA (for 2D / quasi-2D) (referred to as the second precursor in the above description). The next precursor or the next precursors then provide the metal cation B and any missing components from A and / or X and / or optionally MA or FA in the next steps.

[0245] The order of the precursors is therefore not necessarily fixed so that the first precursor contains only B and the second precursor contains only A and X. The order of the precursors is changeable. The components provided by each precursor are also changeable.

[0246] According to a further advantageous embodiment of the invention, the first solvent is selected such that the first precursor is dissolved by the first solvent and / or that the resulting layer of perovskite (or the perovskite deposited as a layer of perovskite) is not dissolved by the first solvent.

[0247] According to a further advantageous embodiment of the invention, the second solvent is selected such that the second precursor is dissolved by the second solvent and / or that the resulting layer of perovskite (or the perovskite deposited as a layer of perovskite) is not dissolved by the second solvent.

[0248] According to a further advantageous embodiment of the invention, the at least one further solvent is selected such that the at least one further precursor is dissolved by the at least one further solvent, and / or that the resulting layer of perovskite (or the perovskite deposited as a layer of perovskite) is not dissolved by the at least one further solvent.

[0249] Preferably, the solvent provided in step i) is also selected such that the first, second and / or at least one further precursor is dissolved by the solvent, and / or that the resulting layer of perovskite (or the perovskite deposited as a layer of perovskite) is not dissolved by the solvent.

[0250] Furthermore, the solvent and / or the solvent mixture and / or the first solvent and / or the second solvent and / or the at least one further solvent is preferably selected such that the resulting reaction byproducts dissolve in the solvent. In the example reaction "Pb(Piv)2 + 3 MAI MAPbh + 2 MAPiv" mentioned above, for example, MAPiv, i.e., methylammonium pivalate, is formed as a reaction byproduct. Thus, the reaction byproducts can be removed from the reaction space and the substrate surface. This advantageously ensures a pure product without reaction byproduct contamination.

[0251] Furthermore, the solvent and / or the solvent mixture and / or the first solvent and / or the second solvent and / or the at least one further solvent is selected such that the perovskite deposited as a perovskite layer does not dissolve in the solvent. In the example reaction "Pb(Piv)2 + 3 MAI MAPbh + 2 MAPiv" mentioned above, for example, the MAPbh, i.e., methylammonium lead(II) iodide or MAPI, is deposited as a perovskite or as a perovskite layer.

[0252] Deviating from the above-mentioned feature, it is possible for the resulting perovskite layer or the perovskite deposited as a perovskite layer to exhibit solubility in the first solvent and / or the second solvent and / or in at least one further solvent. However, this is only possible if the growth rate of the resulting perovskite layer or the perovskite deposited as a perovskite layer nevertheless exceeds the dissolution rate of the resulting perovskite layer or the perovskite deposited as a perovskite layer.

[0253] The first solvent, the second solvent, the at least one further solvent, the first rinsing solvent, the second rinsing solvent, and the at least one further rinsing solvent can comprise nonpolar and / or polar hydrocarbon-containing solvents (alkanes, cyclic alkanes, aromatics, ethers, esters), nonpolar and polar halogenated carbon-based solvents, polar aprotic to protic solvents (alcohols, ketones, aldehydes, sulfoxides, amines, amides). The restrictions according to the invention naturally apply here. The first solvent, the second solvent, and the at least one further solvent each comprise at least 99% of an aprotic solvent and / or an aprotic solvent mixture. The aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.5.Protic solvents can therefore make up a maximum of 1% of the first solvent, the second solvent, or the at least one additional solvent. This applies, for example, to most alcohols, ketones, aldehydes, sulfoxides, amines, or amides because they are protic and polar. The same restrictions preferably apply to the first rinsing solvent, the second rinsing solvent, and / or the at least one additional rinsing solvent.

[0254] The first and / or the second and / or the at least one further solvent is preferably chloroform and / or a mixture of chloroform and isopropanol with a maximum of 0.24 vol% isopropanol.

[0255] Preferably, the total solvent delivered during a complete cycle contains a maximum of 0.24 vol% isopropanol. The total solvent delivered during a complete cycle comprises the first and / or the second and / or the at least one further solvent. Preferably, the total solvent delivered during a complete cycle additionally comprises the first and / or the second and / or the at least one further rinsing solvent.

[0256] According to a further advantageous embodiment of the invention, the first rinsing solvent comprises at least 99% aprotic solvent and / or an aprotic solvent mixture. The aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.5. Preferably, the aprotic solvent and / or the aprotic solvent mixture has / have a coordination ability index of -10 to -0.5, particularly preferably of -4 to -0.5.

[0257] The first rinsing solvent is preferably aprotic.

[0258] According to a further advantageous embodiment of the invention, the second rinsing solvent comprises at least 99% aprotic solvent and / or an aprotic solvent mixture. The aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.5. Preferably, the aprotic solvent and / or the aprotic solvent mixture has / have a coordination ability index of -10 to -0.5, particularly preferably of -4 to -0.5.

[0259] The second rinsing solvent is preferably aprotic. According to a further advantageous embodiment of the invention, the at least one further rinsing solvent comprises at least 99% aprotic solvent and / or an aprotic solvent mixture. The aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.5. The aprotic solvent and / or the aprotic solvent mixture preferably has / have a coordination ability index of -10 to -0.5, particularly preferably of -4 to -0.5.

[0260] The additional rinsing solvent is preferably aprotic.

[0261] According to a further advantageous embodiment of the invention, the first rinsing solvent is selected such that the first precursor is dissolved by the first rinsing solvent and / or that the resulting layer of perovskite (or the perovskite deposited as a layer of perovskite) is not dissolved by the first rinsing solvent.

[0262] According to a further advantageous embodiment of the invention, the second rinsing solvent is selected such that the second precursor is dissolved by the second rinsing solvent and / or that the resulting layer of perovskite (or the perovskite deposited as a layer of perovskite) is not dissolved by the second rinsing solvent.

[0263] According to a further advantageous embodiment of the invention, the at least one further rinsing solvent is selected such that the at least one further precursor is dissolved by the at least one further rinsing solvent, and / or that the resulting layer of perovskite (or the perovskite deposited as a layer of perovskite) is not dissolved by the at least one further rinsing solvent. Furthermore, the first rinsing solvent and / or the second rinsing solvent and / or the at least one further rinsing solvent is preferably selected such that resulting reaction by-products (such as the reaction by-product methylammonium pivalate = MAPiv in the example reaction "Pb(Piv)2 + 3 MAI MAPbh + 2 MAPiv") dissolve in the respective rinsing solvent. The reaction by-products can thus be removed from the reaction space and from the substrate surface.This advantageously ensures a pure product without reaction by-product contamination.

[0264] Furthermore, the first rinsing solvent and / or the second rinsing solvent and / or the at least one further rinsing solvent are selected such that the perovskite deposited as a perovskite layer does not dissolve in the respective rinsing solvent. In the example reaction "Pb(Piv)2 + 3 MAI MAPbh + 2 MAPiv" mentioned above, for example, the MAPbh, i.e., methylammonium lead(II) iodide or MAPI, is deposited as a perovskite or as a perovskite layer.

[0265] Deviating from the above-mentioned feature, it is possible for the resulting perovskite layer or the perovskite deposited as a perovskite layer to exhibit solubility in the first rinsing solvent and / or the second rinsing solvent and / or the at least one further rinsing solvent. However, this is only possible if the growth rate of the resulting perovskite layer or the perovskite deposited as a perovskite layer nevertheless exceeds the dissolution rate of the resulting perovskite layer or the perovskite deposited as a perovskite layer.

[0266] The first and / or the second and / or the at least one further rinsing solvent is preferably chloroform. According to a further advantageous embodiment of the invention, the perovskite layer comprises a three-dimensional perovskite (3D) with a composition ABX3. A is selected from a group comprising [R4- n NH n ] + , [R2N-CH=NR2]+ (each with organic residue R), Rb + , Cs + or mixtures thereof. B is selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof. X is selected from a group comprising F, CI, Br, I, or mixtures thereof.

[0267] The organic radical R is selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, hydrogen atom, or halogen atom. If multiple organic radicals are present, all organic radicals may be identical, or individual organic radicals may be different, or all organic radicals may be different.

[0268] X can be provided by a precursor, in particular by the first or second or further precursor. Preferably, X is provided by multiple precursors, in particular by the first and / or second and / or at least one further precursor.

[0269] In the example reaction "Pb(Piv)2 + 3 MAI MAPbh + 2 MAPiv" mentioned above, for example, MAPbh, i.e., methylammonium lead(II) iodide or MAPI, is deposited as a perovskite or perovskite layer. The methylammonium cation MA has the composition [CH3NH3] + which result from the [R4- n NH n ] + with n = 3 and R = CH3. In this example, B is Pb 2+ and X is I'.

[0270] Further examples of a three-dimensional perovskite (3D) with a composition ABX3 are CsPbBrs and MAxFAi-xPblyC-y. MA again stands for the methylammonium cation. FA stands for the formamidinium cation and has the composition [H2N-CH=NH2] + According to a further advantageous embodiment of the invention, the perovskite layer comprises a two-dimensional or quasi-two-dimensional perovskite (2D or quasi-2D) with a composition A2BX4. A is selected from a group comprising organic ammonium, preferably [RNHs] + and / or [R2NH2] + (with organic residue R), Rb + , Cs + or mixtures thereof. B is selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof. X is selected from a group comprising F; Cl, ​​Br, I; or mixtures thereof.

[0271] The organic radical R is selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0272] X can be provided by a precursor, in particular by the first or second or further precursor. Preferably, X is provided by multiple precursors, in particular by the first and / or second and / or at least one further precursor.

[0273] According to a further advantageous embodiment of the invention, the perovskite layer comprises a two-dimensional or quasi-two-dimensional perovskite (2D or quasi-2D) with a composition A2(MA) n -iB n X3n+i or A2(FA)n-iB n X3n+i. A is selected from a group comprising organic ammonium, preferably [RNHs] + and / or [R2NH2] + (with organic residue R), Rb + , Cs +or mixtures thereof. MA stands for the methylammonium cation, which has the composition [CH3NH3] + FA stands for the formamidinium cation, which has the composition [H2N- CH=NH2] + B is selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof. X is selected from a group comprising F; Cl; Br; I; or mixtures thereof. The organic radical R is selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom, or halogen atom.

[0274] X can be provided by a precursor, in particular by the first or second or further precursor. Preferably, X is provided by multiple precursors, in particular by the first and / or second and / or at least one further precursor.

[0275] According to a further advantageous embodiment of the invention, the perovskite layer comprises a two-dimensional or quasi-two-dimensional perovskite (2D or quasi-2D) with a composition A3B2X9. A is selected from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + (each with organic residue R), Rb + , Cs + or mixtures thereof. B is selected from a group comprising As 3+ , Bi 3+ , Sb 3+ or mixtures thereof. X is selected from a group comprising F, CI, Br, I, or mixtures thereof.

[0276] The organic radical R is selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, hydrogen atom, or halogen atom. If multiple organic radicals are present, all organic radicals may be identical, or individual organic radicals may be different, or all organic radicals may be different.

[0277] X can be provided by a precursor, in particular by the first or second or further precursor. Preferably, X is provided by several precursors, in particular by the first and / or second and / or at least one further precursor. Another example of the perovskite layer results here from the deposition of the hybrid, double-layer, Sb-based perovskite MA3Sb2l9-xCl x This is a perovskite with a composition A3B2X9 where A is the methylammonium cation MA with the composition [CH3NH3] +which results from the [R4- n NH n ] + with n = 3 and R = CH3. In this example, B is Sb 3+ . X is provided as a mixture of CI' and I' anions.

[0278] An example of a two-dimensional perovskite (2D) with a composition of A2BX4 is (pipH)2PbBr4. PipH stands for piperidinium.

[0279] An example of a two-dimensional perovskite (2D) with a composition A2(MA)n-iBnX 3n +i is BA2MAPb2l?, where BA stands for butylammonium.

[0280] According to a further advantageous embodiment of the invention, the process, preferably steps a) to f, optionally including steps g) and h), in particular steps b) to f), optionally including steps g) and h), optionally step i)) is carried out at a temperature in the range from -10°C to 120°C, preferably at a temperature in the range from 10°C to 40°C, preferably at a temperature in the range from 15°C to 25°, particularly preferably at room temperature.

[0281] Room temperature is preferably understood to be a temperature in the range of 17°C to 23°.

[0282] Preferably, steps a) to f), optionally including steps g) and h), in particular steps b) to f), optionally including steps g) and h), and / or optionally step i) are carried out at a temperature in the range from -10°C to 120°C, preferably at a temperature in the range from 10°C to 40°C, more preferably at a temperature in the range from 15°C to 25°, particularly preferably at room temperature.

[0283] According to a further advantageous embodiment of the invention, the process is carried out at a pressure in the range of 0.5 bar to 4 bar, preferably at atmospheric pressure.

[0284] Atmospheric pressure is preferably understood to mean a pressure in the range of 0.9 bar to 1.1 bar.

[0285] Preferably, steps a) to f), optionally including steps g) and h), in particular steps b) to f), optionally including steps g) and h), and / or optionally step i) are carried out at a pressure in the range from 0.5 bar to 4 bar, preferably at atmospheric pressure.

[0286] The temperature and / or pressure is preferably constant during the process.

[0287] Preferably, the temperature and / or the pressure remain constant during steps a) to f), optionally including steps g) and h), in particular during steps b) to f), optionally including steps g) and h), and / or optionally during step i),

[0288] The temperature during the process is preferably below the boiling point of the solvent and / or the first solution and / or the second solution and / or the further solution and / or the first rinsing solvent and / or the second rinsing solvent and / or the further rinsing solvent, particularly preferably below the boiling point of all solvents used. Preferably, the temperature during steps a) to f), optionally including steps g) and h), in particular during steps b) to f), optionally including steps g) and h), and / or optionally during step i) is below the boiling point of the solvent and / or the first solution and / or the second solution and / or the further solution and / or the first rinsing solvent and / or the second rinsing solvent and / or the further rinsing solvent, particularly preferably below the boiling point of all solvents used.

[0289] To provide the temperature, the solvent and / or the first solution and / or the second solution and / or the further solution and / or the first rinsing solvent and / or the second rinsing solvent and / or the further rinsing solvent and / or the reaction space and / or the substrate can be heated.

[0290] According to the invention, a perovskite layer is claimed. The perovskite layer is preferably produced by the method according to the invention. The perovskite is an organic-inorganic and / or a completely inorganic perovskite. An organic-inorganic perovskite is also called a hybrid perovskite.

[0291] The perovskite layer is deposited directly onto a substrate. The perovskite layer has a thickness of 0.5 to 500 nm, preferably 0.5 to 200 nm, preferably 0.5 to 100 nm, more preferably 0.5 to 50 nm, and particularly preferably 0.5 to 10 nm.

[0292] The perovskite layer according to the invention is deposited directly onto the substrate. Thus, there is advantageously no intermediate layer or boundary layer between the substrate and the perovskite layer. The perovskite layer is advantageously simple, flexible, highly reproducible, gentle, scalable, energy-efficient, economical in precursor material, inexpensive, and inexpensive to produce. Further advantages of producing the perovskite layer are described above.

[0293] The perovskite layer is advantageously highly reproducible and scalable.

[0294] The perovskite layer is advantageously particularly stable. This is advantageously ensured by inter- and / or intramolecular interactions between the substrate and the perovskite layer, which are made possible by the fact that the perovskite is deposited directly onto the substrate. Furthermore, inter- and / or intramolecular interactions within the perovskite layer ensure the stability of the perovskite layer.

[0295] The perovskite layer is advantageously transparent and / or semi-transparent.

[0296] Furthermore, the composition of the perovskite layer can advantageously be precisely adjusted. The stoichiometry of the individual components can be adjusted by adjusting the respective precursor concentrations and the respective precursor preparation times.

[0297] The flexibility during the process (for example, the above-described alternating change of one or more precursors in successive cycles) advantageously enables the production of mixed (organic) cation / mixed metal cation / and / or mixed halide perovskites in a controlled manner. According to an advantageous embodiment of the invention, the thickness of the perovskite layer can be precisely adjusted to within 0.1 nm to 5 nm, preferably within 0.1 nm to 2 nm, particularly preferably within 0.1 nm to 1 nm.

[0298] For example, the previously determined layer thickness of the perovskite layer is 9 nm. With an accuracy of 1 nm, the layer thickness of the perovskite layer actually formed in the method according to the invention is between 8.5 nm and 9.5 nm.

[0299] The layer thickness built up per cycle is preferably 0.1 A to 100 A, preferably 0.1 A to 50 A, particularly preferably 1 A to 20 A. Where A stands for Angstroms, 1 A = 0.1 nm. The layer thickness built up in the first cycles per cycle can be greater than the layer thickness built up in the subsequent cycles per cycle. For lead-containing perovskite, for example, CHsNHsPbh (methylammonium lead iodide), the layer thickness built up per cycle is, for example, 12 A, whereas the layer thickness built up in the first cycles per cycle is, for example, 20 A.

[0300] According to a further advantageous embodiment of the invention, the layer of perovskite is homogeneous and / or continuous and / or conformal.

[0301] A homogeneous layer is understood to mean that the layer is evenly distributed over its planar extent. The perovskite layer is homogeneous over at least part of its planar extent. Preferably, the perovskite layer is homogeneous over a large planar extent. The perovskite layer can be homogeneous over its entire planar extent, apart from recesses provided for masking, for example. In particular, the perovskite layer is homogeneous over its entire planar extent. A continuous layer is understood to mean a self-contained layer. A continuous layer is preferably understood to mean a self-contained layer without pores and / or pinholes. The perovskite layer is preferably continuous over its planar extent and / or continuous in its construction direction arranged perpendicular to it.The perovskite layer is preferably continuous above a certain minimum layer thickness. The minimum layer thickness can be 50 nm. Preferably, the minimum layer thickness is 10 nm, particularly preferably 5 nm.

[0302] A conformal coating is understood to reflect the structure of the underlying surface. This is especially true for a structured underlying surface. The conformal coating therefore has the same layer thickness at every position.

[0303] According to a further advantageous embodiment of the invention, the perovskite layer comprises a three-dimensional perovskite (3D) with a composition ABX3. A is selected from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + (each with organic residue R), Rb + , Cs + or mixtures thereof. B is selected from a group comprising Pb2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof. X is selected from a group comprising F, CI, Br, I, or mixtures thereof.

[0304] The organic radical R is selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom, or halogen atom. If multiple organic radicals are present, all organic radicals may be the same, or individual organic radicals may be different, or all organic radicals may be different. X can be provided by a precursor, in particular by the first or second or further precursor. Preferably, X is provided by multiple precursors, in particular by the first and / or second and / or at least one further precursor.

[0305] Organic-inorganic perovskites, i.e., hybrid perovskites, encompass all the compositions mentioned here consisting of an organic and an inorganic component. Components A, B, and X are therefore selected so that at least one organic component and at least one inorganic component are present.

[0306] Completely inorganic perovskites include all compositions mentioned here, with components A, B and X comprising purely inorganic components.

[0307] The perovskite layer, for example, contains the three-dimensional perovskite MAPbh, which is methylammonium lead(II) iodide or MAPI. The methylammonium cation MA has the composition [CH3NH3] + which result from the [R4- n NH n ] + with n = 3 and R = CH3.

[0308] B in this example is Pb 2+ and X is I'.

[0309] Further examples of a three-dimensional perovskite (3D) with a composition ABX3 are CsPbBrs and MA x FAi- x PblyCl3-y. MA again stands for the methylammonium cation. FA stands for the formamidinium cation and has the composition [H2N-CH=NH2] + on.

[0310] According to a further advantageous embodiment of the invention, the perovskite layer comprises a two-dimensional or quasi-two-dimensional perovskite (2D or quasi-2D) with a composition A2BX4. A is selected from a group comprising organic ammonium, preferably [RNHs] + and / or [R2NH2] + (with organic residue R), Rb + , Cs + or mixtures thereof. B is selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+or mixtures thereof. X is selected from a group comprising F; Cl, ​​Br, I; or mixtures thereof.

[0311] The organic radical R is selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0312] According to a further advantageous embodiment of the invention, the perovskite layer comprises a two-dimensional or quasi-two-dimensional perovskite (2D or quasi-2D) with a composition A2(MA) n -iB n X3n+i or A2(FA)n-iB n X3n+i. A is selected from a group comprising organic ammonium, preferably [RNH3] + and / or [R2NH2] + (with organic residue R), Rb + , Cs + or mixtures thereof. MA stands for the methylammonium cation, which has the composition [CH3NH3] + FA stands for the formamidinium cation, which has the composition [H2N- CH=NH2] +B is selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof. X is selected from a group comprising F; Cl; Br; I; or mixtures thereof.

[0313] The organic radical R is selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, H atom or halogen atom.

[0314] According to a further advantageous embodiment of the invention, the perovskite layer comprises a two-dimensional or quasi-two-dimensional perovskite (2D or quasi-2D) with a composition A3B2X9. A is selected from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + (each with organic residue R), Rb + , Cs + or mixtures thereof. B is selected from a group comprising As 3+ , Bi3+ , Sb 3+ or mixtures thereof. X is selected from a group comprising F; Cl, ​​Br, I; or mixtures thereof.

[0315] The organic radical R is selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, hydrogen atom, or halogen atom. If multiple organic radicals are present, all organic radicals may be identical, or individual organic radicals may be different, or all organic radicals may be different.

[0316] X can be provided by a precursor, in particular by the first or second or further precursor. Preferably, X is provided by multiple precursors, in particular by the first and / or second and / or at least one further precursor.

[0317] Organic-inorganic perovskites, i.e., hybrid perovskites, encompass all the compositions mentioned here consisting of an organic and an inorganic component. Components A, B, and X are therefore selected so that at least one organic component and at least one inorganic component are present.

[0318] Completely inorganic perovskites include all compositions mentioned here, with components A, B and X comprising purely inorganic components.

[0319] The perovskites described here contain X from a group comprising F; Cl; Br; I; or mixtures thereof. Therefore, the perovskites described can also be referred to as halide perovskites.

[0320] An example of a two-dimensional perovskite (2D) with a composition A3B2X9 is the hybrid, double-layer, Sb-based perovskite MA3Sb2l9-xCl xIn this example, A is the methylammonium cation MA with the composition [CH3NH3] + , which results from the [R4- n NH n ] + with n = 3 and R = CH3. In this example, B is Sb 3+ . X is provided as a mixture of CI' and I anions.

[0321] An example of a two-dimensional perovskite (2D) with a composition of A2BX4 is (pipH)2PbBr4. PipH stands for piperidinium.

[0322] An example of a two-dimensional perovskite (2D) with a composition A2(MA) n -iB n X3n+i is BA2MAPb2l?, where BA stands for butylammonium.

[0323] According to a further advantageous embodiment of the invention, the layer of perovskite is deposited directly on a planar and / or porous and / or structured, preferably micro- and / or nanostructured, and / or powdered substrate.

[0324] According to a further advantageous embodiment of the invention, the substrate is formed from an oxide and / or metal oxide and / or sulfide and / or metal sulfide and / or metallic material and / or carbon-containing material and / or polymeric material.

[0325] The substrate has at least one substrate surface. Preferably, the substrate has exactly one substrate surface on which the perovskite layer is deposited.

[0326] The substrate can be planar in some areas and / or porous in some areas and / or structured in some areas, preferably micro- and / or nanostructured in some areas, and / or powdery in some areas. For example, the substrate can be planar in one area of ​​the substrate surface and structured, preferably micro- and / or nanostructured, on the remaining substrate surface. Preferably, the substrate is planar over the entire substrate surface and / or porous over the entire substrate surface and / or structured, preferably micro- and / or nanostructured, over the entire substrate surface.

[0327] The substrate may have a coating with an oxide and / or metal oxide and / or sulfide and / or metal sulfide and / or metallic material and / or carbonaceous material and / or polymeric material.

[0328] The substrate can be rigid or flexible. The substrate can have any desired geometry. The substrate is preferably substantially or completely cuboid-shaped. Thus, the substrate preferably has a planar extension and a thickness (and / or height) perpendicular thereto. The thickness of the substrate is preferably significantly smaller than the planar extension of the substrate.

[0329] The substrate preferably has a planar extension in the range of 0.01 cm 2 up to 20000 cm 2 , preferably in the range of 100 cm 2 up to 10000 cm 2 , particularly preferably in the range of 1000 cm 2 up to 5000 cm 2 , on.

[0330] Preferably, the perovskite layer is formed over the entire substrate surface. Therefore, the perovskite layer preferably covers an area in the range of 0.01 cm 2 up to 20000 cm 2 , preferably in the range of 100 cm2 up to 10000 cm 2 , particularly preferably in the range of 1000 cm 2 up to 5000 cm 2 .

[0331] The actual surface area of ​​structured or powdered substrates is preferably significantly larger than the planar extent of the substrate. Powdered substrates, in particular nanopowder substrates, preferably have an actual surface area of ​​50 m 2 / g up to 500 m 2 / g, for example from 200 m 2 / g. The substrate preferably has a thickness in the range of 0.01 cm to 5 cm, particularly preferably in the range of 0.1 cm to 1 cm.

[0332] If the substrate is structured, it preferably has a relief. The relief can have a comparatively large ratio between the depth of the relief and the width of the relief.

[0333] The substrate is made of tin oxide, for example. The substrate can be pretreated by exposing it to UV radiation and / or Os gas. This pretreatment can be followed by immersing the substrate in an aqueous KCl solution.

[0334] The perovskite layer is advantageously conformal with the substrate. The substrate can be planar and / or porous and / or structured, preferably micro- and / or nanostructured, and / or powdered.

[0335] A structured substrate, preferably a micro- and / or nanostructured substrate, advantageously offers a significantly larger surface area compared to a planar substrate. This larger surface area allows more light to be absorbed even with a comparatively thin perovskite layer. The perovskite layers can be made extremely thin (as described above). This advantageously allows for material and cost savings.

[0336] The perovskite layer can be part of a solar cell, e.g. a silicon solar cell.

[0337] According to the invention, the use of an inventive

[0338] A perovskite layer is used as a light-absorbing layer in a solar cell. The light-absorbing layer can also be a photoactive layer.

[0339] According to the invention, the use of a perovskite layer according to the invention as part of a photovoltaic semiconductor junction for the purpose of constructing a tandem solar cell, in particular based on silicon, is further claimed.

[0340] According to the invention, the use of a perovskite layer according to the invention in optoelectronics is further claimed.

[0341] According to the invention, the use of a layer of perovskite according to the invention for modifying the interface between substrate and perovskite in an otherwise conventionally produced perovskite-based component is further claimed.

[0342] The perovskite layer can generally be used as a photoactive layer, for example, in photovoltaics. In particular, the perovskite layer can be used in planar and nanostructured, transparent or semi-transparent solar cells. The perovskite layer can be used as a light absorber.

[0343] Furthermore, the perovskite layer can be used in optoelectronic devices, sensors, lasers, detectors (e.g. for X-rays), catalytic electrodes, fuel cells, and / or storage devices.

[0344] It is also conceivable to use the perovskite layer as a light-absorbing and / or photoactive layer in a solar cell to power devices operated indoors. Such solar cells are also referred to as indoor PV or IPV. The devices can be IoT devices, for example. A non-toxic perovskite layer, especially a lead-free perovskite layer, is preferably used.

[0345] The perovskite layer according to the invention can be used as a light-absorbing and / or photoactive layer in a flexible and / or transparent or semi-transparent solar cell.

[0346] Furthermore, the perovskite layer can be used as an adhesion layer directly on a substrate to improve the adhesion between the substrate and a thicker perovskite layer produced by a conventional process.

[0347] The perovskite layer according to the invention, in particular a sufficiently thin perovskite layer according to the invention, can be used to modify the interface between the substrate and the perovskite in an otherwise conventionally manufactured perovskite-based component. This use advantageously improves the adhesion between the substrate and the conventionally applied perovskite.

[0348] Of course, the above-mentioned features of a perovskite layer according to the invention can also be used equivalently in a process according to the invention. Likewise, the features mentioned above for the process according to the invention can specify the perovskite layer according to the invention.

[0349] In the following, the invention is explained using exemplary embodiments with the aid of the attached figures. The exemplary embodiments shown are therefore not to be understood as limiting. Fig. 1 A Schematic representation of an atomic

[0350] Liquid-phase layer deposition (“sALD”) with two precursors.

[0351] Fig. 1 B Schematic representation of the surface reactions taking place in an s-ALD cycle.

[0352] Fig. 2 Schematic representation of a setup for carrying out the method according to the invention.

[0353] Fig. 3 Flowchart of a first exemplary method according to the invention.

[0354] Fig. 4 Flowchart of a second exemplary method according to the invention.

[0355] Fig. 5 (a) Saturation behavior of the growth of a layer of the perovskite MAPI as a function of the preparation time of the precursor and the rinsing time;

[0356] (b) Linear increase of layer thickness with increasing number of sALD cycles.

[0357] Fig. 6 SEM images of (a) an uncoated SnO2 substrate and (b) a SnO2 substrate coated with a layer of the perovskite MAPI with 15 sALD cycles.

[0358] Fig. 7 EDX maps of a layer of the perovskite MAPI on a

[0359] SnO2 substrate. Fig. 8 GI-XRD diffractogram of a sALD deposited

[0360] MAPI layer after 30 cycles (upper curve) on a SnO2 substrate (lower curve, uncoated reference).

[0361] Fig. 9 (a) Optical absorption spectra of MAPI films after different numbers of cycles and (b) determination of the optical band gap using the Tauc method.

[0362] Fig. 10 X-ray photoelectron spectroscopic analysis of a

[0363] MAPI films.

[0364] Fig. 11 Time-resolved photoluminescence of different MAPI

[0365] Films.

[0366] Fig. 12 Characterization of a functional solar cell based on a sALD-MAPI layer.

[0367] Fig. 13 Atomic force microscopy characterization of a sALD-

[0368] MAPI Films (30 cycles) on SnÜ2.

[0369] Fig. 14 SEM image of a homogeneous layer of the hybrid

[0370] Perovskite MA3Sb2lg-xClx after 75 cycles of sALD on the substrate TiO2.

[0371] Fig. 15 GI-XRD diffractogram of the layer from the hybrid

[0372] Perovskite MA3Sb2lg-xClx.

[0373] Fig. 16 In-situ QCM measurements on a developing layer of

[0374] MA3Sb2lg-xClx. Fig. 17 Spectroscopic ellipsometry measurements on MA3Sb2l9-xClx layers after different numbers of cycles.

[0375] Fig. 18 JV curves for a layer of MA3Sb2l9-xClx on a

[0376] Substrate made of TiO2.

[0377] Fig. 19 Chemical structures for suitable counterions or coordinating ligands.

[0378] Fig. 1 A shows a schematic representation of atomic layer deposition from the liquid phase using two precursors. The term "solution atomic layer deposition" (abbreviated to "solution ALD" or "sALD") is also commonly used for atomic layer deposition from the liquid phase.

[0379] Atomic layer deposition is a process for producing thin films based on self-limiting surface reactions between two (or more) molecular precursors and a substrate surface. In a self-limiting surface reaction, only a limited number of binding partners are available to each precursor. The respective surface reactions occur sequentially and are separated temporally and / or spatially, thus preventing direct reaction between the precursors. The self-limiting behavior of the surface reactions leads to strong control of the film thickness with precision down to the angstrom range. With atomic layer deposition, it is not only possible to conformally coat flat substrates but also substrates with high aspect ratios (e.g., porous and / or nanostructured and / or powdered substrates).The layer thickness deposited per cycle is preferably constant. In other words, the total deposited layer thickness exhibits a linear behavior depending on the number of cycles completed. Therefore, the growth of the layers using ALD is highly controllable and scalable.

[0380] As shown in Fig. 1A, the precursors 1, 2 are each dissolved in a solvent to form a solution. In addition, pure solvent is used as rinsing solvent 3. A microfluidic reactor 4 forms a reaction chamber for carrying out the atomic layer deposition from the liquid phase. Several pumps 5 are designed to pump the solutions of the precursors 1, 2 and / or the rinsing solvent 3 into the reaction chamber. The pumps 5 can be peristaltic pumps and / or syringe pumps. The pumps 5 transport the respective liquids individually through channels in a predetermined order into the reaction chamber. In the embodiment shown, the channels are designed as tubes 6. The tubes 6 are made of chemically resistant materials such as PTFE, PVDF and / or PEEK. In the reaction chamber, the precursors 1, 2 react with the substrate surface in a self-limiting surface reaction.

[0381] Alternatively to the embodiment shown, only one pump 5 can be provided to pump the solutions of the precursors 1, 2 and / or the rinsing solvent 3 into the reaction chamber. For this purpose, the pump 5 is connected to several channels that can be controlled independently of one another.

[0382] The perovskite layer produced in the process according to the invention comprises organic-inorganic and / or completely inorganic perovskite. Organic-inorganic perovskite is also referred to as hybrid perovskite. Fig. 1B shows a schematic representation of the surface reactions taking place in an s-ALD cycle. In an exemplary process according to the invention, one cycle comprises four different steps. In a first step, the first precursor 1 (for example, lead(II) pivalate or abbreviated Pb(Piv)2, shown in Fig. 1B as building blocks Pb and X) reacts in a self-limiting manner with all available surface-reactive functional groups (e.g., -OH groups on the substrate surface). Methylammonium pivalate (shown in Fig. 1B as building blocks MA and X) is formed as a reaction product remaining in the solution or as a reaction by-product in this reaction. In a second step (not shown in Fig.In a third step (shown in Fig. 1B), excess amounts of the first precursor 1 and possible reaction by-products are removed from the reaction space by conveying the rinsing solvent 3. In a third step, the second precursor 2 (for example, methylammonium iodide or abbreviated MAI, shown in Fig. 1B as building blocks MA and I) reacts in a self-limiting manner with the first precursor 1 deposited on the substrate surface. As a reaction product remaining in the solution or as a reaction by-product, methylammonium pivalate (shown in Fig. 1B as building blocks MA and X) is also formed in this reaction. In a fourth step (not shown in Fig. 1B), excess amounts of the second precursor 2 and possible reaction by-products are removed from the reaction space by conveying the rinsing solvent 3. With these four steps, an sALD cycle is completed in the exemplary process according to the invention.

[0383] In the sALD cycle just explained (more precisely in the third step), the following chemical reaction takes place:

[0384] Pb(Piv)2+ 3 MAI MAPbh + 2 MAPiv,

[0385] The abbreviations used are explained below:

[0386] Pb(Piv)2= lead(II) pivalate,

[0387] MAI = methylammonium iodide, MAPbh = MAPI = methylammonium lead(II) iodide, MAPiv = methylammonium pivalate.

[0388] The reaction product is the perovskite MAPI. MAPI stands for methylammonium lead(II) iodide, but can also be referred to as methylammonium iodoplumbate. Using the sALD process just described, a layer of MAPI is built up cycle by cycle, i.e., successively.

[0389] Another example of the perovskite layer results from the deposition of the hybrid, bilayer, Sb-based perovskite MA3Sb2l9-xClx.

[0390] A key prerequisite for the sALD process is that the solvent is capable of completely dissolving the precursors and any possible reaction by-products. On the other hand, the solvent either does not dissolve the perovskite layer, the desired reaction product, or only dissolves it to such a small extent that the growth rate of the perovskite layer exceeds the dissolution rate. The precursors are ionic in nature, while the counterions have ligand character. This allows the precursors (and reaction by-products) to be dissolved in solvents with low polarity, but prevents the dissolution of the ionic perovskite as a reaction product. The precursors are dissolved in the respective solution at a concentration in the low mmol range, i.e., at a concentration of 1–10 mmol.

[0391] The aforementioned small amounts of precursors, the cost-effective equipment, and the process operation under ambient conditions (preferably at room temperature and atmospheric pressure) make sALD an easily accessible and resource-efficient technique. Fig. 2 shows a schematic representation of an exemplary setup for carrying out the inventive method for producing perovskite layers using sALD. The pump 5 is connected to the reactor 4, which comprises a slot nozzle head, via the hoses 6. Furthermore, the reactor 4 is connected to a control unit 7 via a control line 7a and to a temperature controller 8 via a signal line 8a.

[0392] The parameters of the slot nozzle head, such as speed or travel distance, are adapted to the requirements of the respective process for the deposition of organic-inorganic (hybrid) and / or fully inorganic perovskites. The sALD process for producing perovskite layers is typically carried out at room temperature, making it a very gentle process. If necessary, the solutions and / or the substrate surface can be heated to higher temperatures. A peristaltic or syringe pump, chemically resistant tubing (e.g., Viton or PTFE), and chemically resistant tubing connections (e.g., PEEK or PVDF) are used to sequentially and cyclically transport the dissolved precursors and the pure rinse solvent to the slot nozzle head of the sALD setup and onto the substrate.Typical flow rates for the precursors and the rinsing solvent(s) in this setup can be between 0.5 ml / min and 10 ml / min. However, lower or higher flow rates can also be set as required. The preparation time for the respective precursors is, for example, in the range of a few seconds, while the rinsing time ranges from several seconds to several minutes. The preparation time and rinsing time can be adapted to the requirements of the sALD and can vary depending on the sALD process and the size of the system. Using MAPI as an example as a hybrid perovskite, flow rates of 1 ml / min to 1.5 ml / min and preparation times of 10 s for the respective precursors and rinsing times of 220 s are preferably used for the sALD process.Depending on the process requirements, the solvent used to dissolve the precursors in sALD for the production of perovskite layers can include, for example, nonpolar and polar hydrocarbon solvents (alkanes, cyclic alkanes, aromatics, ethers, esters), nonpolar and polar halogenated carbon solvents, and polar aprotic and even protic solvents (alcohols, ketones, aldehydes, sulfoxides, amines, amides). Of course, the restrictions of the invention apply. The solvent used comprises at least 99% aprotic solvent and / or an aprotic solvent mixture. The aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.5. Protic solvents can therefore make up a maximum of 1% of the solvent used.This applies, for example, to most alcohols, ketones, aldehydes, sulfoxides, amines or amides because they are protic and polar.

[0393] In the example of the hybrid perovskite MAPI (methylammonium iodoplumbate or methylammonium lead(II) iodide), dry, anhydrous chloroform (CHCh) and dry, anhydrous isopropanol (PrOH) are used as solvents to dissolve the precursors, for example lead(II) pivalate or abbreviated Pb(Piv)2 with 1 mmol concentration and for example methylammonium iodide or abbreviated MAI with 4 mmol concentration. Pure, dry, anhydrous chloroform (CHCl3) is used as a rinsing solvent.

[0394] Planar or non-planar substrates of various types can be used as substrates for the deposition of the perovskite layer using sALD. Non-planar substrates are preferably structured substrates, particularly preferably nanostructured substrates. The substrate can be formed from an oxide and / or metal oxide and / or sulfide and / or metal sulfide and / or metallic material and / or carbonaceous material and / or polymeric material. In the example of sALD from MAPI, for example, a tin oxide substrate is used. The substrate is subjected to a pretreatment, for example, before the deposition of the perovskite layer. The pretreatment includes UV irradiation and ozone treatment followed by immersion in an aqueous KCl solution.Such pretreatment of the substrates is not a prerequisite for successful deposition of the perovskite layer using sALD, but can be part of the process to modify the properties of the perovskite layer. Using MAPI as an example, the successful deposition of the hybrid perovskite layer using sALD is demonstrated by a visibly brown coating on the substrate (in this case, glass).

[0395] Fig. 3 shows a flowchart of an exemplary first method according to the invention for producing a perovskite layer. The following steps are preferably performed in the following order.

[0396] In a step S01 of the first method according to the invention, a substrate made of SiO2 is provided in a reaction space.

[0397] In a step S02, the reaction space is filled with a solvent mixture of chloroform and isopropanol (with 0.2 vol% isopropanol).

[0398] In step S03, a 1 mmol / L solution of the precursor Pb(Piv)2 (i.e., lead(II) pivalate or lead(II)-[-O2CC(CH3)3]2) in a solvent mixture of chloroform and 0.2 vol% isopropanol is pumped into the reaction chamber. This deposits the precursor Pb(Piv)2 onto the substrate. In step S04, chloroform is pumped into the reaction chamber as a rinsing solvent. This removes residues of the precursor Pb(Piv)2 and any reaction byproducts from the reaction chamber.

[0399] In step S05, a 4 mmol / L solution of the precursor methylammonium iodide ([CPhNHs] ! or abbreviated MAI) in a solvent mixture of chloroform and 0.2 vol% isopropanol is pumped into the reaction chamber. The precursor MAI reacts with the precursor Pb(Piv)2 previously deposited on the substrate, thereby forming the perovskite methylammonium lead(II) iodide (MAPbh , abbreviated MAPI). This creates a layer of MAPI.

[0400] In summary, the following chemical reaction takes place: Pb(Piv)2+ 3 MAI MAPbh + 2 MAPiv,

[0401] Methylammonium pivalate (abbreviated MAPiv) is produced in the solution as a reaction by-product.

[0402] In step S06, chloroform is pumped into the reaction chamber as a rinsing solvent. This removes residues of the precursor MAI, the reaction byproduct MAPiv, and any other reaction byproducts from the reaction chamber.

[0403] Steps S03 to S06 are repeated 49 times, resulting in a total of 50 cycles. A 64 nm MAPI layer thickness is produced. The layer thickness built up per cycle is 20 A in the first few cycles and approaches 12 A as the repetitions progress.

[0404] In step S07, the substrate coated with the MAPI layer is dried. In addition to the solvent evaporating spontaneously, the substrate is dried by exposure to an inert gas stream of N2.

[0405] In a step S08, the substrate coated with the layer of MAPI is removed from the reaction chamber.

[0406] Fig. 4 shows a flow diagram of an exemplary second method according to the invention for producing a layer of perovskite.

[0407] The following steps are preferably performed in the order shown below.

[0408] In a step S11 of the second method according to the invention, the reaction space of an sALD system is filled with a solvent mixture of chloroform and isopropanol (with 0.2 vol% isopropanol).

[0409] In a step S12, a substrate made of SiCh is provided in the reaction space.

[0410] In step S13, a 1 mmol / L solution of the precursor Pb(Piv)2 (i.e., lead(II) pivalate or lead(II)-[-O2CC(CH3)3]2) in a solvent mixture of chloroform and 0.2 vol% isopropanol is pumped into the reaction chamber. The precursor Pb(Piv)2 is deposited on the substrate.

[0411] In step S14, chloroform is pumped into the reaction chamber as a rinsing solvent. This removes residues of the precursor Pb(Piv)2 and any reaction byproducts from the reaction chamber.

[0412] In step S15, a 1 mmol / L solution of the precursor Snh (i.e., tin(II) iodide) in a solvent mixture of chloroform and 0.2 vol% isopropanol is pumped into the reaction chamber. The precursor Snh is deposited on the substrate. The precursor Snh can then react with the Pb(Piv)2 already deposited on the substrate surface to form Pbh.

[0413] In step S16, chloroform is pumped into the reaction chamber as a rinsing solvent. This removes residues of the precursor Snh and any reaction byproducts from the reaction chamber.

[0414] In step S17, a 4 mmol / L solution of the precursor methylammonium iodide ([CHsNHs] ! or abbreviated MAI) in a solvent mixture of chloroform and 0.2 vol% isopropanol is pumped into the reaction chamber. The precursor MAI reacts with the precursor Pb(Piv)2 previously deposited on the substrate, with the precursor Snh previously deposited on the substrate, and / or with the Pbh formed by a reaction between Pb(Piv)2 and Snh, thereby forming the perovskite MAPbo.sSno.sh. This creates a layer of MAPbo.sSno.sh. Methylammonium pivalate (abbreviated MAPiv) is formed in the solution as a reaction byproduct.

[0415] In step S18, chloroform is pumped into the reaction chamber as a rinsing solvent. This removes residues of the precursor MAI, the reaction byproduct MAPiv, and any other reaction byproducts from the reaction chamber.

[0416] Steps S13 to S18 are repeated until the layer of the perovskite MAPbo.sSno.sh has reached a total layer thickness of 50 nm.

[0417] In step S19, the substrate coated with the MAPbo.sSno.sh layer is removed from the reaction chamber. In step S20, the substrate coated with the MAPbo.sSno.sh layer is dried. For this purpose, the substrate is heated to a temperature of 45°C for a period of 10 minutes.

[0418] Fig. 5 (a) shows the saturation behavior of the growth of a perovskite layer as a function of the precursor preparation time and the rinsing time for a sALD process on SnCh-coated Si / SiCh wafers. Pb(Piv)2 and MAI are used as precursors. Each growth rate is derived from three thickness measurements using spectroscopic ellipsometry.

[0419] For this purpose, two saturation experiments were conducted using the example of MAPI deposition using sALD. By varying the respective preparation times of the first precursor Pb(PiV)2 (1 mmol in CHCh) and the second precursor MAI (4 mmol in a mixture of one part i-PrOH and 8 parts CHCl3) between 1 s and 20 s while maintaining the purge time of 250 s, a constant growth rate is achieved starting at a minimum preparation time of 8 s (curve beginning at the bottom). The self-limiting surface reaction of the precursors thus comes to an end after these 8 s. Below this value, complete coverage of the substrate surface cannot yet be guaranteed.

[0420] This saturation experiment is supplemented by another saturation experiment in which the purge time is varied from 80 s to 270 s (curve starting at the top). The preparation time for both precursors is kept constant at 12 s. The experimental data show that a purge time of at least 200 s is required to avoid uncontrolled, direct contact between the two precursors. In both saturation experiments, the growth rate per cycle (GPC) saturates at a constant value of approximately 20 A per cycle. Based on these data, a preparation time of 10 s for each precursor and a purge time of 200 s appear advantageous. Fig. 5 (b) shows the linear increase in the thickness of the perovskite layer using MAPI as an example with increasing number of sALD cycles. The layer thickness is determined by spectroscopic ellipsometry.The linear growth behavior of the perovskite layer is accompanied by a constant layer thickness, which is additionally deposited in each sALD cycle. The process according to the invention therefore enables highly controlled deposition of perovskite layers with a layer thickness in the range of a few nanometers or in the low tens of nanometers.

[0421] Fig. 6 shows SEM images of (a) an uncoated SnCh substrate and (b) a SnCh substrate with 15 sALD cycles of a thin layer of MAPI. SEM stands for scanning electron microscope.

[0422] According to Fig. 6 (b), after only 15 cycles of sALD, a nearly closed, particulate, smooth and homogeneous layer of MAPI is deposited on a substrate (here SnCh on a silicon wafer) compared to the uncoated SnCh substrate (see Fig. 4 (a)).

[0423] Energy-dispersive X-ray spectroscopy (EDX) analysis performed on an uncoated SnCh reference substrate and an SnCh substrate coated with MAPI after 30 sALD cycles shows the presence of all elements expected during deposition of this hybrid perovskite (C, N, I, Pb) and all expected elements of the substrate (O, Sn, Si). More importantly, the absence of any impurities (the negligible amount of K could be due to a KCl pretreatment step) and the slight increase in O content during deposition demonstrate the high purity of the hybrid perovskite layer. Table 1: Results of an EDX analysis of an uncoated SnO2 substrate on a Si / SiO2 wafer (reference) and a similar SnO2 substrate coated with 30 cycles of MAPI by sALD.

[0424] Fig. 7 shows EDX maps of a layer of the perovskite MAPI on a SnO2 substrate. The corresponding SEM image is shown in the top row. The middle and bottom rows show maps with respect to Si, Sn, O (from the substrate) and C, Pb, and I (from the MAPI layer). C may also originate from a small amount of random carbon. The EDX maps show that the deposited MAPI layer consists only of the expected elements. This suggests that the process according to the invention produces highly pure perovskite layers.

[0425] Fig. 8 shows a GI-XRD diffractogram of a MAPI layer deposited by sALD after 30 cycles (upper curve) on a SnCh substrate. The lower curve shows a comparison measurement of an uncoated SnO2 substrate as an uncoated reference. GI-XRD stands for "grazing-incidence X-ray diffraction". The measurement reveals crystal facets of MAPI, which can be assigned according to the Crystallographic Open Database, COD no. 7218931. This proves the direct deposition of perovskite as a thin layer. However, no evidence of Pbh was found, which would represent an impurity and is the typical degradation product of MAPI. This once again proves the purity of the deposited perovskite layer. Advantageously, the perovskite layer (in this example, MAPI) grows directly in crystalline form.Therefore, advantageously, no subsequent annealing step is required. Direct growth as a crystalline material, especially as a polycrystalline material, enables thin layers of perovskite to be epitaxially deposited directly onto a preferred substrate. Advantageously, the process according to the invention is carried out under mild conditions, especially at room temperature and atmospheric pressure.

[0426] Fig. 9 (a) shows optical absorption spectra of MAPI films after different cycle numbers. The upper curve results from a MAPI film after 70 cycles, the middle curve results from a MAPI film after 40 cycles, and the lower curve results from a MAPI film after 20 cycles. Fig. 9 (b) shows the determination of the optical band gap using the Tauc method for the MAPI film after 70 cycles.

[0427] Figure 10 shows an X-ray photoelectron spectroscopic analysis of a MAPI film. In addition to the overall spectrum, finer measurements of the peaks for the relevant elements (Pb, I, N, C) are shown. The measured elemental composition is listed in the table above.

[0428] Fig. 11 shows time-resolved photoluminescence measurements of different MAPI films deposited by sALD (K27, 40 nm; K28, 80 nm; K30, 170 nm) and of MAPI films deposited using traditional techniques (Sample 1, Sample 3, 40 nm; Sample 4, Sample 5, 80 nm; Sample 2, 170 nm). The MAPI films deposited by sALD consistently show higher values ​​than the MAPI films deposited using traditional techniques. Fig. 12 shows a characterization of a functional solar cell based on an sALD-MAPI layer: ITO / 30 nm SnO2 / 137c MAPI (~180 nm) / spiro-OMeTAD / Au. The upper plot shows the current-voltage characteristic under irradiation by simulated sunlight (AM 1.5). The lower plot shows a quantum efficiency spectrum.

[0429] Fig. 13 shows an atomic force microscopy characterization of a sALD-MAPI film (30 cycles) on SnO2. The roughness (defined as root-mean-squares) is 15 nm.

[0430] Table 2: Electrical parameters determined using the Hall method on a MAPI film (sALD deposited)

[0431] In the following, several measurements of a layer deposited by sALD from the two-dimensional hybrid Sb-based perovskite MA3Sb2lg-xClx are shown.

[0432] The experimental details for the preparation of the MA3Sb2lg-xClx layer are as follows:

[0433] 1 mmol of a 1:4 mixture of SbCh and Sbh as the first precursor dissolved in toluene and 0.5 mmol of MAPiv (methylammonium pivalate) as the second precursor, also dissolved in toluene, react in an sALD process to yield MA3Sb2l9-xClx. A sALD setup with a slotted nozzle is used. Toluene is used as the rinsing solvent. The preparation time of the precursors is 20 s each, and the rinsing time is 120 s. SiO2 and TiO2 are used as substrates.

[0434] Fig. 14 shows an SEM image of the hybrid Sb-based perovskite MAsSbJg-xClx layer. 75 cycles of MAsSbJg-xClx were deposited on a TiO2 substrate using sALD. The SEM image shows a homogeneous perovskite layer.

[0435] Fig. 15 shows the lower curve of a GI-XRD diffractogram of a layer of the same hybrid Sb-based perovskite MA3Sb2Ig-xClx. The upper curve shows a simulated curve. The GI-XRD measurement demonstrates the crystalline growth of the hybrid perovskite at room temperature. Thus, the process according to the invention advantageously produces a crystalline perovskite directly, without an elevated temperature during the process and without a subsequent annealing step.

[0436] Fig. 16 shows in-situ measurements using a quartz crystal microbalance (QCM) on a developing layer of MA3Sb2lg-xClx. The oscillation frequency Av is plotted as a function of time At. The individual curves differ in the respective provision time and / or purge time. In the first curve from the top, the provision time is 20 s and the purge time is 120 s. In the second curve from the top, the provision time is 40 s and the purge time is 120 s. In the third curve from the top, the provision time is 60 s and the purge time is 120 s. In the bottom curve, the provision time is 40 s and the purge time is 180 s. The measurements demonstrate the growth of the layer of the hybrid Sb-based perovskite MAsSbdg-xClx with each sALD cycle. The data indicate a minimum preparation time of 20 s and a minimum purge time of 120 s. Figure 17 shows spectroscopic ellipsometry measurements.The individual curves differ in the number of sALD cycles. Two curves are shown for each sample with respect to ellipticity and orientation. The first curve from the top represents the uncoated TiO2 substrate. The second curve from the top represents a layer of MA3Sb2l9-xClx deposited with 25 sALD cycles. The third curve from the top represents a layer of MA3Sb2lg-xClx deposited with 50 sALD cycles. The bottom curve represents a layer of MA3Sb2lg-xClx deposited with 75 sALD cycles. The measurements show a linear shift with increasing number of sALD cycles. This further confirms the linear growth behavior of the perovskite layer.

[0437] Fig. 18 shows JV curves from a feasibility study for the fabrication of solar cells with a layer of MA3Sb2Ig-xClx on a TiO2 substrate. J is the current density in milliamperes per square centimeter. The curves refer to several individual solar cells and several different measurement parameters, such as the voltage drive rate.

[0438] Fig. 19 shows the chemical structures of halides, alkoxides, carboxylates, beta-diketonates, amides, silylamides, stannylamides, imides, amidinates, guanidinates, pyrazolates, and 1,4-diazabutadienes. M represents a central metal ion. R, R1, R2, R3, R4, R5, and Re each represent an organic radical. The organic radical is preferably selected from a group comprising alkyl group, aryl group, hydroxyl group, amino group, alkoxy group, hydrogen atom, or halogen atom.

[0439] The molecules shown can be present as negatively charged counterions or coordinating ligands in the precursors used in the process according to the invention. For example, they can be bound to a doubly positively charged cation such as Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or to a triply positively charged cation B such as As 3+ , Bi 3+ , Sb 3+ be bound.

[0440] It is clear to the person skilled in the art that the above-mentioned embodiments of the features of the perovskite layer, the process or individual process steps can be combined with each other as desired and do not represent any limitation, in particular in their design and combination.

[0441] List of reference symbols

[0442] 1 first precursor 2 second precursor

[0443] 3 rinsing solvents

[0444] 4 reactor

[0445] 5 pumps

[0446] 6 Hoses 7 Control unit

[0447] 7a Control line

[0448] 8 temperature controllers

[0449] 8a Signal line

Claims

Claims 1. A method for producing a layer of perovskite, wherein the perovskite is an organic-inorganic and / or a completely inorganic perovskite, the method comprising the following steps, preferably in the following order: a) providing a substrate in a reaction chamber, wherein the substrate has a substrate surface, b) conveying a first solution into the reaction chamber, wherein the first solution is formed from a first precursor and a first solvent, wherein the first precursor reacts with the substrate surface and is deposited on the substrate, and wherein preferably a residual portion of the first precursor and / or reaction by-products remains in the first solution, c) conveying a first rinsing solvent into the reaction chamber,wherein the portion of the first precursor preferably remaining in the first solution and / or the remaining reaction by-products is / are completely or substantially completely removed from the reaction space, d) conveying a second solution into the reaction space, wherein the second solution is formed from a second precursor and a second solvent, wherein the second precursor reacts with the precursor last chemically bound to the substrate surface and on the, substrate is deposited, wherein preferably a residual portion of the second precursor and / or reaction by-products remains / remain in the second solution, e) conveying a second rinsing solvent into the reaction space, wherein the portion of the second precursor preferably remaining in the second solution and / or the remaining reaction by-products is / are completely or substantially completely removed from the reaction space, f) repeating steps b) to e), wherein the first precursor in step b) preferably does not react with the substrate surface, but reacts with the precursor last chemically bound to the substrate surface, wherein the first solvent comprises at least 99% an aprotic solvent and / or an aprotic solvent mixture, wherein the aprotic solvent and / or the aprotic solvent mixture has a dipole moment of at most 1,54 Debye and preferably a coordination ability index of at most -0.5, wherein the second solvent comprises at least 99% an aprotic solvent and / or an aprotic solvent mixture, wherein the aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.5, and wherein the perovskite layer is formed by a chemical bonding of the second precursor with the precursor immediately previously chemically bonded to the substrate surface in step d).

2. The method according to claim 1, wherein the following steps are carried out once or several times between step c) and step d): g) conveying a further solution into the reaction space, wherein the further solution consists of a further precursor and a further Solvent is formed, wherein the further precursor preferably reacts with the precursor last chemically bound to the substrate surface and is deposited on the substrate, wherein preferably a residual portion of the further precursor and / or reaction by-products remains / remain in the further solution, and h) conveying a further rinsing solvent into the reaction space, wherein the portion of the further precursor preferably remaining in the further solution and / or the remaining reaction by-products is / are completely or essentially completely removed from the reaction space, wherein the further solvent comprises at least 99% an aprotic solvent and / or an aprotic solvent mixture, wherein the aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.

5.

3. The process according to claim 1 or 2, wherein the following step is carried out before step a) or simultaneously with step a) or between steps a) and b): i) filling the reaction space with a solvent which comprises at least 99% an aprotic solvent and / or an aprotic solvent mixture, wherein the aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.

5.

4. A method according to any one of the preceding claims, wherein the following step is carried out after step f): j) drying the substrate coated with the layer of perovskite.

5. Method according to one of the preceding claims, wherein the following step is carried out after step f): k) removing the substrate coated with the layer of perovskite from the reaction chamber.

6. Method according to one of the preceding claims, wherein the substrate is planar and / or porous and / or structured and / or powdery, and / or wherein the substrate is formed from an oxide and / or metal oxide and / or sulfide and / or metal sulfide and / or metallic material and / or carbonaceous material and / or polymeric material.

7. The method according to any one of the preceding claims, wherein the first precursor is ionic or molecular with coordination character, and / or wherein the first precursor is dissolved in the first solution at a concentration of 0.1 to 100 mmol / L, preferably 0.1 to 50 mmol / L, particularly preferably 0.1 to 10 mmol / L, most particularly preferably 0.1 to 5 mmol / L.

8. Method according to one of the preceding claims, wherein the first precursor is used to produce a layer of three-dimensional perovskite with a composition ABX3 or to produce a layer of two-dimensional or quasi-two-dimensional perovskite with a composition A2BX4 or with a composition A2(MA) n -i B n X3n+i or with a composition A2(FA) n -i B n X3n+i is chosen so that the first precursor is a doubly positively charged cation B from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof, and negatively charged counterions and / or coordinating ligands from a group comprising halide anion X as negatively charged counterion, carboxylate anion, alkoxides, beta-diketonate anion, amides, Imides, silylamides, stannylamides, amidinates, guanidinates, pyrazolates, 1,4-diazabutadienes or mixtures thereof, wherein the negatively charged counterions and / or coordinating ligands are bound to B, or wherein the first precursor for producing a layer of two-dimensional or quasi-two-dimensional perovskite with a composition A3B2X9 is selected such that the first precursor is a triply positively charged cation B from a group comprising As 3+ , Bi 3+ , Sb 3+ or mixtures thereof, and contains negatively charged counterions and / or coordinating ligands from a group comprising halide anion X as negatively charged counterion, carboxylate anion, alkoxides, beta-diketonate anion, amides, imides, silylamides, stannylamides, amidinates, guanidinates, pyrazolates, 1,4-diazabutadienes or mixtures thereof, wherein the negatively charged counterions and / or coordinating ligands are bonded to B.

9. The method according to any one of the preceding claims, wherein the second precursor is ionic or molecular with coordination character, and / or wherein the second precursor is dissolved in the second solution at a concentration of 0.1 to 100 mmol / L, preferably 0.1 to 50 mmol / L, particularly preferably 0.1 to 10 mmol / L, most particularly preferably 0.1 to 5 mmol / L.

10. The method according to any one of the preceding claims, wherein the second precursor for producing a layer of three-dimensional perovskite with a composition ABX3 is selected such that the second precursor is a singly positively charged cation A from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + , Rb + , Cs +, or mixtures thereof, and a singly negatively charged counterion and / or a coordinating ligand from a group comprising halide anion X as negatively charged counterion, carboxylate anion, beta-diketonates, or mixtures thereof, wherein the singly negatively charged counterion and / or the coordinating ligand G is bound to A, or wherein the second precursor for producing a layer of two-dimensional or quasi-two-dimensional perovskite with a composition A2BX4 is selected such that the second precursor is a singly positively charged cation A from a group comprising organic ammonium, Rb + , Cs +, or mixtures thereof, and a singly negatively charged counterion and / or a coordinating ligand G from a group comprising halide anion X as negatively charged counterion, carboxylate anion, beta-diketonates, or mixtures thereof, wherein the singly negatively charged counterion and / or the coordinating ligand G is bound to A, or wherein the second precursor for producing a layer of two-dimensional or quasi-two-dimensional perovskite with a composition A2(MA) n -iB n X3n+i or A2(FA) n -iB n X3n+i is chosen so that the second precursor is a singly positively charged cation A from a group comprising organic ammonium, Rb + , Cs +, or mixtures thereof, contains a singly positively charged methylammonium cation MA or a singly positively charged formamidinium cation FA, and contains a singly negatively charged counterion and / or a coordinating ligand G from a group comprising halide anion X as negatively charged counterion, carboxylate anion, beta-diketonates, or mixtures thereof, wherein the singly negatively charged counterion and / or the coordinating ligand G is bound to A, or wherein the second precursor for producing a layer of two-dimensional or quasi-two-dimensional perovskite with a composition A3B2X9 is selected such that the second precursor contains a singly positively charged cation A from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + , Rb + , Cs +, or mixtures thereof, and a singly negatively charged counterion and / or a coordinating ligand G from a group comprising halide anion X as negatively charged counterion, carboxylate anion, beta-diketonates, or mixtures thereof, wherein the singly negatively charged counterion and / or the coordinating ligand G is bound to A.

11. Method according to one of the preceding claims, wherein the at least one further precursor is ionic or molecular with coordination character, and / or wherein the further precursor is dissolved in the further solution at a concentration of 0.1 to 100 mmol / L, preferably 0.1 to 50 mmol / L, particularly preferably 0.1 to 10 mmol / L, most particularly preferably 0.1 to 5 mmol / L.

12. Method according to one of the preceding claims, wherein the first precursor, the second precursor and preferably the at least one further precursor are selected such that they provide the components A, B, X and optionally MA or FA of the perovskite layer to be formed, wherein for the production of a layer of three-dimensional perovskite with a composition ABX3, the component A is selected from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + , Rb + , Cs + or mixtures thereof, component B is a divalent metal cation, and component X is a halide anion, or wherein, for producing a layer of two-dimensional or quasi-two-dimensional perovskite with a composition A2BX4, component A is selected from a group comprising organic ammonium, Rb + , Cs +or mixtures thereof, component B is a divalent metal cation, and component X is a halide anion, or wherein for producing a layer of two-dimensional or quasi-two-dimensional perovskite with a composition A2(MA) n -iB n X3n+i or A2(FA) n -i B n Xsn+i is component A from a group comprising organic ammonium, Rb + , Cs + or mixtures thereof, the component MA is a methylammonium cation or the component FA is a Formamidinium cation, component B is a divalent metal cation, and component X is a halide anion, or wherein, for producing a layer of two-dimensional or quasi-two-dimensional perovskite with a composition A3B2X9, component A is selected from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + , Rb + , Cs +or mixtures thereof, component B is a trivalent metal cation, and component X is a halide anion, and / or that the first precursor, the second precursor and preferably the at least one further precursor react with one another to form the layer of perovskite, wherein the layer of perovskite is not soluble in the first, the second and preferably the at least one further solvent.

13. The method according to any one of the preceding claims, wherein the first solvent is selected such that the first precursor is dissolved by the first solvent, and / or that the resulting layer of perovskite is not dissolved by the first solvent, and / or wherein the second solvent is selected such that the second precursor is dissolved by the second solvent, and / or that the resulting layer of perovskite is not dissolved by the second solvent, and / or wherein the at least one further solvent is selected such that the at least one further precursor is dissolved by the at least one further solvent, and / or that the resulting layer of perovskite is not dissolved by the at least one further solvent.

14. The method according to any one of the preceding claims, wherein the first rinsing solvent comprises at least 99% of an aprotic solvent and / or an aprotic solvent mixture, wherein the aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.5, and / or wherein the second rinsing solvent comprises at least 99% an aprotic solvent and / or an aprotic solvent mixture, wherein the aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.5, and / or wherein the at least one further rinsing solvent comprises at least 99% an aprotic solvent and / or an aprotic solvent mixture, wherein the aprotic solvent and / or the aprotic solvent mixture has / have a dipole moment of at most 1.54 Debye and preferably a coordination ability index of at most -0.

5.

15. The method according to any one of the preceding claims, wherein the first rinsing solvent is selected such that the first precursor is dissolved by the first rinsing solvent, and / or that the resulting layer of perovskite is not dissolved by the first rinsing solvent, and / or wherein the second rinsing solvent is selected such that the second precursor is dissolved by the second rinsing solvent, and / or that the resulting layer of perovskite is not dissolved by the second rinsing solvent, and / or wherein the at least one further rinsing solvent is selected such that the at least one further precursor is dissolved by the at least one further rinsing solvent, and / or that the resulting layer of perovskite is not dissolved by the at least one further rinsing solvent.

16. A method according to any one of the preceding claims, wherein the layer of perovskite comprises a three-dimensional perovskite having a composition ABX3, wherein A is selected from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + , Rb + , Cs + or mixtures thereof, wherein B is selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof, and wherein X is selected from a group comprising F; Cl, ​​Br, I; or mixtures thereof.

17. A method according to any one of the preceding claims, wherein the layer of perovskite comprises a two-dimensional or quasi-two-dimensional perovskite having a composition A2BX4, wherein A is selected from a group comprising organic ammonium, Rb + , Cs +or mixtures thereof, wherein B is selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof, and wherein X is selected from a group comprising F; CI Br; I; or mixtures thereof, and / or wherein the layer of perovskite is a two-dimensional or quasi-two-dimensional perovskite having a composition A2(MA) n -iB n X3n+i or A2(FA)n-iB n X3n+i, where A is selected from a group comprising organic ammonium, Rb + , Cs + or mixtures thereof, wherein MA stands for the methylammonium cation, wherein FA stands for the formamidinium cation, wherein B is selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+or mixtures thereof, and wherein X is selected from a group comprising F; Cl; Br; I; or mixtures thereof, and / or wherein the layer of perovskite comprises a two-dimensional or quasi-two-dimensional perovskite with a composition A3B2X9, wherein A is selected from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + , Rb + , Cs + or mixtures thereof, wherein B is selected from a group comprising As 3+ , Bi 3+ , Sb 3+ or mixtures thereof, and wherein X is selected from a group comprising F; Cl; Br; I; or mixtures thereof.

18. A process according to any one of the preceding claims, wherein the process is carried out at a temperature in the range of -10°C to 120°C, preferably at a temperature in the range of 10°C to 40°C, preferably at a temperature in the range of 15°C to 25°, particularly preferably at room temperature, and / or wherein the process is carried out at a pressure in the range of 0.5 bar to 4 bar, preferably at atmospheric pressure.

19. A layer of perovskite, preferably produced by a process according to any one of the preceding claims, wherein the perovskite is an organic-inorganic and / or a completely inorganic perovskite, wherein the layer of perovskite is deposited directly on a substrate, wherein the layer of perovskite has a layer thickness of 0.5 to 500 nm, preferably of 0.5 to 200 nm, more preferably of 0.5 to 100 nm, more preferably of 0.5 to 50 nm, particularly preferably of 0.5 to 10 nm.

20. A perovskite layer according to claim 19, wherein the layer thickness of the perovskite layer is adjustable to an accuracy of 0.1 nm to 5 nm, preferably to an accuracy of 0.1 nm to 2 nm, particularly preferably to an accuracy of 0.1 nm to 1 nm.

21. A perovskite layer according to claim 19 or 20, wherein the perovskite layer is homogeneous and / or continuous and / or conformal.

22. A perovskite layer according to any one of claims 19 to 21, wherein the perovskite layer comprises a three-dimensional perovskite having a composition ABX3, wherein A is selected from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + , Rb + , Cs + or mixtures thereof, wherein B is selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+or mixtures thereof, and wherein X is selected from a group comprising F, CI, Br, I, or mixtures thereof.

23. A perovskite layer according to claim 19 to 22, wherein the perovskite layer comprises a two-dimensional or quasi-two-dimensional perovskite having a composition A2BX4, wherein A is selected from a group comprising organic ammonium, Rb + , Cs + or mixtures thereof, wherein B is selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof, and wherein X is selected from a group comprising F; CI Br, I; or mixtures thereof, and / or wherein the layer of perovskite is a two-dimensional or quasi-two-dimensional perovskite having a composition A2(MA) n -iB n X3n+i or A2(FA)n-iB nX3n+i, where A is selected from a group comprising organic ammonium, Rb + , Cs + or mixtures thereof, wherein MA stands for the methylammonium cation, wherein FA stands for the formamidinium cation, wherein B is selected from a group comprising Pb 2+ , Sn 2+ , Ge 2+ , Sr 2+ , CD 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 2+ or mixtures thereof, and wherein X is selected from a group comprising F; CI Br; I; or mixtures thereof, and / or wherein the layer of perovskite comprises a two-dimensional or quasi-two-dimensional perovskite with a composition A3B2X9, wherein A is selected from a group comprising [R4- n NH n ] + , [R2N-CH=NR2] + , Rb + , Cs + or mixtures thereof, wherein B is selected from a group comprising As 3+ , Bi 3+ , Sb 3+or mixtures thereof, and wherein X is selected from a group comprising F; Cl; Br; I; or mixtures thereof.

24. A perovskite layer according to any one of claims 19 to 23, wherein the perovskite layer is deposited directly on a planar and / or porous and / or structured and / or powdered substrate, and / or wherein the substrate is formed from an oxide and / or metal oxide and / or sulfide and / or metal sulfide and / or metallic material and / or carbonaceous material and / or polymeric material.

25. Use of the perovskite layer according to any one of claims 19 to 24 as a light-absorbing layer in a solar cell, and / or Use of the perovskite layer according to one of claims 19 to 24 as part of a photovoltaic semiconductor junction for the purpose of constructing a tandem solar cell, in particular based on silicon, and / or Use of the perovskite layer according to one of claims 19 to 24 in optoelectronics, and / or Use of the perovskite layer according to one of claims 19 to 24 for modifying the interface between substrate and perovskite in an otherwise conventionally produced perovskite-based component.

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