Method for the synthesis of organic iodides, perovskite-forming compositions containing organic iodides, and photovoltaic cells having perovskite layers obtained therefrom

Abstract

General formula R x Method for obtaining salts having NI, wherein R x N is an organic cation (R x N + ) and R is an organic substituent R 1 -, R 2 -, R 3 -, and hydrogen (H-), and x represents an organic cation R x N + is the number of substituents R- directly bonded to the nitrogen (N) atom in - The method includes the steps of synthesizing hydrogen iodide (HI) in situ by mixing molecular iodine (I) and formic acid (COOH) in a solvent medium in a molar ratio of molecular iodine (I):formic acid (COOH) of 1.01:1 or greater, and dissolving an organic cation R x N + The donor compound of organic cation R is 1.01:1 or more. x N + and introducing a compound of general formula R x and maintaining the reaction mixture at a temperature of 20°C or greater for a time necessary to obtain a reaction product that is a salt with NI. The resulting product is a base material for the synthesis of perovskite.

Description

[Technical field]

[0001] The present invention relates to a compound having the general formula (R x The present invention relates to a method for obtaining an organic iodide that is a salt with at least one iodide having a structure having a molecular weight of 1,000 to 1,000,000, and a method for obtaining an organic iodide that is a salt with at least one iodide ... [Background technology]

[0002] Photoactive coatings are used to fabricate photovoltaic cells, semiconductor devices used to convert solar radiation into electricity. In a photovoltaic cell, the photoactive layer acts as the solar light (photon) absorber and is usually applied as the visible surface of the cell coated with a suitable solar-transmissible (semi-transparent / transparent) electrode material.

[0003] One known type of photoactive coating is photoactive ink. One advantage of photoactive ink is that there is an easy and inexpensive way to apply the ink to a substrate, i.e., the ink is printed, where the choice of printing technique depends on the scale of production, the type of substrate, and the physical properties of the ink, such as the viscosity and adhesive properties of the ink.

[0004] There are known organic photoactive inks that contain organic film-forming materials in the form of doped polymers or monomers that are polymerizable after their application to a target substrate.

[0005] For example, U.S. Patent Application No. US20130087744 describes a compound of formula M B A photovoltaic ink composition is described that comprises a polymeric precursor having the formula (ER)3, where M Bis a metal selected from the group In, Ga, or Al; E is S or Se; and R represents an alkyl, aryl, heteroaryl, alkenyl, amido, or silyl moiety. Organic materials such as aliphatic and aromatic hydrocarbons, as well as siloxanes, cyclosiloxanes, silicone fluids, acetonitrile, esters, and ethers are used as ink solvents. The inks are represented by the molecular formula M alk M B (ER)4 or formula M alk (ER), wherein M alk is Li, Na, or K, and R is an alkyl or aryl moiety. Other ink components are surfactants, dispersants and emulsifiers, defoamers, viscoelasticity modifiers, antioxidants, and adhesion promoters. Depending on the composition, the ink is in the form of a suspension or a solution prepared by mixing all the components. The ink acts as a photovoltaic layer and is applied to the substrate by printing. To solidify the applied coating, the ink is dried by evaporation of the solvent.

[0006] Moreover, perovskites are known materials used to obtain photovoltaic cells. Perovskites are hybrid organic-inorganic compounds with the general formula ABX3, where A is an organic methylammonium cation (CH3NH3 + ), the presence of which enhances the solubility of the material and makes the perovskite suitable for thin layer applications; B is the lead cation (Pb 2+ ) and the anion X is typically iodide (I - ), bromide (Br - ), or chloride (Cl - The perovskite is prepared in the form of a film, i.e. a thin coating, which constitutes the photoactive layer of a photovoltaic cell, where, in a cell having a standard architecture, the perovskite layer is located between a layer of p-type conductive material and a layer of n-type conductive material, which are typically covered with suitable electrodes, including one electrode that allows the transmission of solar photons.

[0007] Perovskite thin films intended for the photoactive layer of a photovoltaic cell are prepared from a perovskite-forming composition, which is a colloidal solution containing perovskite precursors, i.e. the substrates for a particular perovskite synthesis, constituting the dispersed phase, where the colloid contains a suitable liquid, usually an organic solvent, as the dispersion medium.

[0008] Binary perovskite-forming compositions are also known that contain two physically separate components that, after mixing, react to form a perovskite.

[0009] In the perovskite-forming compositions constituting the colloidal solution, the colloidal particles typically take the form of coordination complexes represented by the structures of lead polyhalides between organic and inorganic components, which may be adjusted by varying the degree of coordination of the complexes, thereby allowing the formation of perovskite layers in the form of thin films with predetermined film coverage parameters and the morphology of the resulting perovskite structures.

[0010] There are also known perovskite-forming compositions in the form of inks containing at least one perovskite precursor, in which the mechanism of curing, i.e., of forming a photoactive coating, involves the synthesis of a perovskite from the perovskite precursor contained in the composition.

[0011] International Patent Application WO2016088019 discloses a film-forming composition containing at least two perovskite precursors, such as CH3NH3I and PbI2, or NH2CH=NH2I and PbI2, or CsI and SnI2. The composition may take the form of a powder or ink and may contain additives including dimethylformamide (DMF) or isopropanol (IPA) as a solvent, and thickeners such as glycerol or d-sorbitol, and crystallization retarders such as dimethylsulfoxide (DMSO). A method for curing the composition on a selected substrate to form a photoactive layer consists in applying a layer of the composition having a suitable thickness to the substrate, and curing the composition to synthesize the appropriate perovskite from its precursors, and evaporating the solvent, if present in the composition. According to WO2016088019, depending on the form and components of the film-forming composition, the film-forming composition may be applied to the substrate using spin-coating techniques, printing and heating the applied layer, or applying a coating from the gas phase, including dual source deposition, or using ablation techniques, or printing techniques, including in particular inkjet printing, as well as spraying techniques, blade coating, meniscus coating, slot-die coating, or dip coating. The resulting photoactive layer features good absorption of photons, while the prepared photovoltaic cell comprising the perovskite film obtained by curing the film-forming composition shows good efficiency.

[0012] In addition, the scientific publication "Unraveling the hidden function of a stabilizer in a precursor in improving hybrid perovskite film morphology for high efficiency solar cells" by Zhengguo Xiao et al., Energy & Environmental Science, DOI: 10.1039 / c6ee00183a, published on January 28, 2016, describes the synthesis of organometallic alkyl halides "OPT" (organometallic trihalide perovskites) containing three atoms of each halogen. The publication describes the role of phosphoric acid (I), also called phosphinic acid H3PO2, in stabilizing hydrogen iodide HI, which is necessary for the synthesis of perovskite precursors from the OPT group - methylammonium iodide (MAI - methylammonium iodide). In fact, the presence of phosphoric acid (I), H3PO2, as a stabilizer of hydrogen iodide HI during the synthesis of MAI leads to contamination of the reaction product with methylammonium hypophosphite MAH2PO2, which is due to H3PO2 reacting with methylamine (MA). Said contamination induces a significant decrease in the crystallization reaction rate, i.e., the synthesis of perovskite from MAI contaminated with MAH2PO2 and PbI2 (lead iodide) due to the formation of the intermediate phase Pb(H2PO2)2, resulting in a very uniform and smooth perovskite layer with larger grains. And then, the synthesis of perovskite using MAI purified from MAH2PO2 by recrystallization leads to a coarse-grained, inhomogeneous perovskite film, which indicates that contamination with MAH2PO2 promotes the synthesis of perovskite. The authors of the publication propose to use Pb(H2PO2)2 as a nucleation center for perovskite crystals.

[0013] The scientific publication "Enhanced optoelectronic quality of perovskite thin films with hypophosphorous acid for planar heterojunction solar cells" by Wei Zhang et al., published on November 30, 2015, in NATURE COMMUNICATIONS, DOI: 10.1038 / ncomms10030, describes perovskite semiconductors such as CH3NH3PbI3. The authors of the publication mention the addition of phosphoric acid (I) (HPA) to a solution of perovskite precursors, which converts the oxide I2 (molecular iodine) into I - The quality of the resulting perovskite films is significantly improved due to the HPA reducing to (iodide anion), which improves the stoichiometry of the resulting perovskite crystals.

[0014] Another scientific publication by Wei Zhang et al., "Ultrasmooth organic-inorganic perovskite thin-film formation and crystallization for efficient planar heterojunction solar cells", NATURE COMMUNICATIONS, DOI:10.1038 / ncomms7142, published on January 30, 2015, describes the role of anions in the synthesis of perovskite in solution and how they affect the growth of perovskite crystals and, consequently, the fabrication and quality of perovskite films. The authors of the publication used lead acetate (Pb(OAc)2) instead of the traditionally used lead chloride (PbCl2) or lead iodide (PbI2), which resulted in faster growth of perovskite crystals and a smoother surface for the perovskite film. Also, the heating time during the preparation of perovskite CH3NH3PbI3 using the precursors Pb(OAc)2 and MAI is shorter, which is attributed to the facilitated removal of excess CH3NH3OAc from the mixture.

[0015] According to the aforementioned publications, the concentration of the perovskite precursors in the perovskite-forming composition as well as all of the above-mentioned methods for preparing and purifying the perovskite precursors for the perovskite-forming composition in the form of a colloidal solution substantially affect the quality and morphology of the resulting perovskite film crystals prepared using a particular composition.

[0016] Therefore, methods for obtaining perovskite precursors, i.e. raw materials for perovskite synthesis, are continually modified so as to obtain compounds with an appropriate degree of purity for use in preparing perovskite-forming compositions for excellent perovskite coatings exhibiting appropriate morphology and quality of crystals, and, as a consequence, better and better properties of photovoltaic cells using such coatings as light-sensitive elements. Summary of the Invention [Problem to be solved by the invention]

[0017] It would therefore be useful to develop methods for the synthesis of perovskite precursors, as well as perovskite compositions containing said precursors, that allow for the preparation of perovskite coatings that exhibit improved morphology and quality of perovskite crystals. [Means for solving the problem]

[0018] General formula R x A method for obtaining a salt having a NI, wherein R x N is an organic cation (R x N + ) where R is an organic substituent R 1 -, R 2 -, R 3 represents a substituent (R-) independently selected from the group consisting of -, and hydrogen (H-), and x represents an organic cation R x N + is the number of substituents R- directly bonded to the nitrogen (N) atom in the -The method includes the steps of synthesizing hydrogen iodide (HI) in situ by mixing molecular iodine (I2) and formic acid (COOH) in a solvent medium in a molar ratio of molecular iodine (I2):formic acid (COOH) of 1.01:1 or greater; x N + A compound that is a donor of organic cation R with a ratio of 1.01:1 or more x N + and introducing a compound of general formula R x and maintaining the reaction mixture at a temperature of 20° C. or greater for a period of time necessary to obtain a reaction product that is a salt having an NI.

[0019] Preferably, the organic cation R x N + The donor of R is independently selected from the group consisting of linear or branched alkyl substituents containing 1 to 8 carbon atoms in the substituted molecule and optionally containing at least one heteroatom replacing a carbon or hydrogen atom in the substituted molecule. 1 -, R 2 - and optionally R 3 - moieties as organic substituents, where the heteroatoms are selected from the group consisting of silicon, oxygen, nitrogen, sulfur, iodine, chlorine, and bromine.

[0020] Preferably, the iodine molecule (I2) is mixed with formic acid (HCOOH) in a molar ratio of 1.01:1 to 1.1:1 of iodine molecule (I2):formic acid (COOH), and the organic cation R x N + The donor is an organic cation R in the range of 1.01:1 to 1.50:1. x N + The donor is introduced into the solvent medium in an amount that gives a molar ratio of donor:molecular iodine (I2).

[0021] Preferably, molecular iodine (I2) is mixed with formic acid (HCOOH) in a molar ratio of 1.01:1 iodine (I2):formic acid (COOH).

[0022] Preferably, the reaction mixture is heated to a temperature in the range of 20 to 80°C.

[0023] Preferably, the organic cation R x N + The donor is introduced into the solvent medium following the in situ synthesis of hydrogen iodide (HI).

[0024] Preferably, the amine is an organic cation R x N + and the resulting salt (R x NI) is an alkylammonium cation (R(H3)N + ), dialkylammonium cation R2(H2)N + , and trialkylammonium cations (R(H)N + an organic cation (R x N + ) is contained.

[0025] Preferably, the primary alkylamine having the general formula RNH2 is x N + The resulting salt, an alkyl ammonium iodide, has the general formula R(H3)NI, where the substituent R represents an alkyl moiety containing from 1 to 8 carbon atoms.

[0026] Preferably, methylamine is the organic cation R x N + to give methylammonium iodide (MAI) as the salt.

[0027] Preferably, octylamine is a cation R x N + to give octylammonium iodide (OAI) as a salt.

[0028] Preferably, the amidine salt is an organic cation R x N + It is used as a donor for amidinium iodide (R2N-(R 3)C=N(H2)I) is obtained as the salt.

[0029] Preferably, formamidine acetate is the organic cation R x N + to give formamidinium iodide (FAI) (H2N-C(H)=N(H2)I) as a salt.

[0030] Preferably, the solvent medium comprises at least one compound selected from the group consisting of methanol, ethanol, absolute ethanol, isopropanol, dioxane, tetrahydrofuran (THF), and dimethylformamide (DMF).

[0031] Preferably, the solvent medium is water.

[0032] Preferably, the step of preparing the reaction mixture comprises in a solvent medium a compound of the general formula R x It further includes the step of introducing a catalyst which is a salt having an NI.

[0033] Preferably, the catalyst is the reaction product salt R x It is the same compound as NI.

[0034] Preferably, the catalyst is obtained by a method according to the present disclosure.

[0035] Preferably, the catalyst is introduced at a molar ratio of catalyst:molecular iodine (I2) ranging from 0.01:1 to 0.03:1.

[0036] Furthermore, perovskite-based compounds of the general formula R prepared using the method according to the present disclosure can be used as substrates in the synthesis of perovskites. x The use of salts with NI is disclosed.

[0037] Furthermore, compounds of the general formula R obtained using the method according to the present disclosure x Perovskite-forming compositions are disclosed that include salts having a NI.

[0038] Preferably, the composition comprises an ammonium iodide having the general formula R selected from the group consisting of methylammonium iodide (MAI), ethylammonium iodide, propylammonium iodide, butylammonium iodide, pentylammonium iodide, hexylammonium iodide, heptylammonium iodide, octylammonium iodide (OAI), and formamidinium iodide (FAI). x Includes salts having NI.

[0039] Preferably, the composition further comprises at least one lead salt and at least one solvent.

[0040] Preferably, the composition further comprises methylammonium dihydrogen phosphate(I) CH3NH3H2PO2.

[0041] Preferably, the composition comprises the following compounds, methylammonium iodide (MAI), anhydrous lead(II) acetate (CH3COO)2Pb, and lead(II) chloride PbCl2, in amounts effective for the synthesis of perovskite from the above compounds, as well as dimethylformamide (DMF) as a solvent, and methyl ammonium dihydrogen phosphate(I), CH3NH3H2PO2, in an amount of 0.3% by weight relative to the weight of methylammonium iodide (MAI) contained in the composition.

[0042] Preferably, the composition comprises formamidinium iodide (FAI), methylammonium bromide CH3NH3Br, lead (II) iodide PbI2, and cesium iodide (CsI) in amounts effective for the synthesis of perovskite from the above compounds.

[0043] The general formula R obtained using the method according to the present disclosure x Further disclosed is a photovoltaic cell that includes a perovskite layer prepared using a salt having Ni.

[0044] Preferably, the battery comprises a perovskite layer obtained from a perovskite-forming composition comprising components as described above.

[0045] The object of the invention is illustrated in exemplary embodiments in the drawings. [Brief description of the drawings]

[0046] [Figure 1A] 1 is a schematic representation of the synthesis reaction of organic iodides (RxNI) using methods according to the present disclosure. [Figure 1B] 1 is a schematic representation of the synthesis reaction of organic iodides (RxNI) using methods according to the present disclosure. [Figure 2A] 1 is a schematic representation of the synthesis reaction of methylammonium iodide (MAI) using a method according to the present disclosure. [Figure 2B] 1 is a schematic representation of the synthesis reaction of methylammonium iodide (MAI) using a method according to the present disclosure. [Figure 3A] 1 is a schematic representation of the synthesis reaction of octylammonium iodide (OAI) using a method according to the present disclosure. [Figure 3B] 1 is a schematic representation of the synthesis reaction of octylammonium iodide (OAI) using a method according to the present disclosure. [Figure 4A] 1 is a schematic representation of the synthesis reaction of formamidinium iodide (FAI) using a method according to the present disclosure. [Figure 4B] 1 is a schematic representation of the synthesis reaction of formamidinium iodide (FAI) using a method according to the present disclosure. [Diagram 5] 1 is a schematic representation of structural and semi-structural formulae of exemplary organic iodides obtained using methods according to the present disclosure. [Figure 6] An example of the synthesis of perovskites from iodides obtained using the method according to the present disclosure is given. [Figure 7A] FIG. 1 shows an SEM image of a perovskite coating in the form of a thin film on a PEDOT / PET / ITO substrate. [Figure 7B] FIG. 1 shows an SEM image of a perovskite coating in the form of a thin film on a PEDOT / PET / ITO substrate. [Figure 7C] FIG. 1 shows an SEM image of a perovskite coating in the form of a thin film on a PEDOT / PET / ITO substrate. [Figure 8A] 1 shows X-ray diffractograms under stress of MAI synthesized using the method according to the invention and of CH3NH3PbI3 obtained using MAI synthesized using the method according to the invention with the addition of MAH2PO2. [Figure 8B] For comparison with FIG. 8A, an enlarged peak corresponding to the reflection (110) at the tetragonal plane of the perovskite phase is shown. [Figure 8C] The expanded peak corresponding to the PET material (control) is shown. [Figure 9A] FIG. 1 shows the results of cell efficiency (η) measurements, which determine the energy conversion efficiency of a cell, as a function of the type of perovskite-forming composition used to form the perovskite layer of the cell. [Figure 9B] 1 shows test results depicting the current density-voltage dependence for selected perovskite cells. [Figure 10] The results of aging tests performed on selected cells (aging at maximum power point, under 0.8 sunlight, in an inert atmosphere, and at a temperature of 32° C.) are shown. [Figure 11A] FIG. 1 shows an SEM image of a perovskite coating prepared using Composition I of Example VIII. [Figure 11B] FIG. 1 shows an SEM image of a perovskite coating prepared using Composition II of Example VIII. [Figure 12A] X-ray diffractograms of loaded networks of two perovskites are shown. [Figure 12B] Shown is an enlarged peak corresponding to the reflection (100) in the tetragonal plane of the perovskite phase. [Figure 13] 4 shows the current density-voltage dependence for the prepared batteries. [Figure 14A] 1 shows an image of a colloid containing MAI obtained using a method according to the present invention. [Figure 14B] 1 shows images of colloids of the same composition containing MAI (commercially available MAI) obtained using a prior art method. [Figure 14C]Photographs of MAI obtained using a prior art method and a colloid of the same composition containing MAI that had been recrystallized once are shown. [Figure 14D] Photographs of MAI obtained using a prior art method and a colloid of the same composition containing MAI that had been recrystallized three times are shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] The method according to the invention that has been developed makes it possible to prepare a group of chemical formulations to be used as perovskite precursors, the chemical formulations having the general formula R x N, with ion notation RxN + I - wherein R x N + is an organic cation, and I - is an iodide anion, and x is the number of substituents directly bonded to the nitrogen atom, preferably x is 3 to 4 (when x=3, a double bond in the organic cation is present between the nitrogen atom and the carbon atom in one R moiety).

[0048] R x The methods developed to prepare the NI compounds ensure improved purity of the obtained products, thus enabling them to be used as perovskite precursors in various perovskite-forming compositions, including colloidal solutions such as inks, to create perovskite coatings with improved morphology and quality of the perovskite crystals.

[0049] The developed method of iodide synthesis differs from the prior art methods in that the method according to the present disclosure includes a step of obtaining hydrogen iodide (HI) in situ in the reaction medium. In other words, according to the developed method, hydrogen iodide (HI) is not used as a direct substrate for the synthesis of the respective iodide. Instead, the developed method includes a step of providing a substrate suitable for in situ hydrogen iodide (HI) synthesis to the reaction medium.

[0050] The developed method is x It is possible to obtain various compounds which are iodide salts with NI, in which the organic cation R x N + teeth - Alkyl ammonium cation R 1 (H3)N + , dialkylammonium cation R 1 R 2 (H2)N + , and a trialkylammonium cation R 1 R 2 R 3 (H)N + The general formula R + (x=4), and - Amidinium cation R 1 R 2 N-(R 3 )C=N(H2) + and formamidinium cation R 1 R 2 NC(H)=N(H2) + The general formula R + (x=3), in which the moiety R- is a group H-, R-, 1 -, R 2 - and R 3 -. The substituents R-, R 1 -, R 2 -, R 3 - is hydrogen (H-), linear and / or branched aliphatic hydrocarbons (C y H z The moieties may be the same or different and are selected from the group consisting of organic cations (R − ), alicyclic hydrocarbons, and aromatic hydrocarbons. Preferably, the moieties are organic cations other than (H−) (R x N + ) all the substituents R-, R 1 -, R 2 -, R 3- may contain 1 to 8 carbon atoms in the molecule, i.e., the general formula C y H z At least one substituent R-, R 1 -, R 2 -, R 3 -, y may be 1 to 8. Also, at least one substituent R of the organic cation 1 -, R 2 -, R 3 - means that at least one carbon or hydrogen atom may be replaced with another atom, such as silicon, oxygen, nitrogen, sulfur, iodine, chlorine, or bromine.

[0051] For example, the developed method can be used to extract iodide salts (R x NI), in which the organic cation (R x N + )teeth, - For x=4, methylammonium CH3(H3)N + , Ethylammonium CH3CH2(H3)N + , Propylammonium C3H7(H3)N + , Butylammonium C4H9(H3)N + , Pentylammonium H3C5H 11 N + , Hexylammonium H3C6H 13 N + , Heptylammonium CH 15 (H3)N + , or octylammonium CH 17 (H3)N + is a cation, - and for x=3, formamidinium (H2N-HC=NH2) + , or guanidinium (H2N)2-C=NH2) + It is a cation.

[0052] For greater clarity, examples of iodide salts that may be obtained using the method of the invention are shown in the form of structural or semi-structural formulas in FIG. 5, where formula I and formula II are general formulas of iodides, in which formula I represents salts with the general formula R4NI (i.e. x=4), formula II represents salts R3NI (i.e. x=3), and formula III, formula IV and formula V respectively give detailed examples of compounds that may be obtained using the developed method, where formula III represents methylammonium iodide (MAI), formula IV represents octylammonium iodide (OAI) and formula V represents formamidinium iodide (FAI).

[0053] The developed method thus makes it possible to obtain iodide salts R4NI (Figure 5, formula I), such as methylammonium iodide (MAI), dimethylammonium iodide, propylammonium iodide, methylethylammonium iodide, butylammonium iodide, pentylammonium iodide, hexylammonium iodide, heptylammonium iodide, octylammonium iodide (OAI), and iodide salts with the general formula R3NI (Figure 5, formula II), such as formamidinium iodide (FAI) or guanidinium iodide (GAI).

[0054] 1-4 are schematic representations of the reactions occurring during synthesis according to the developed method, with Figs. 1A, 2A, 3A, and 4A showing synthesis without the use of a catalyst, while Figs. 1B, 2B, 3B, and 4B showing synthesis with an optional catalyst. x The method developed to prepare NI was - Iodine molecule I2 is reacted with formic acid (HCOOH) in excess and with an organic cation (R x N + ) is supplied to the reaction medium in a shortage relative to the donor, - formic acid (HCOOH) is provided in the amounts indicated above relative to molecular iodine (I2) to produce hydrogen iodide (HI) in situ (in the reaction medium) with the release of carbon dioxide (CO2), a by-product of the HI synthesis; - Organic cation Rx N + is provided to the reaction medium in an amount corresponding to the amount of molecular iodine (I2) indicated above, - and an organic cation donor R x N + The donors react with in situ synthesized hydrogen iodide (HI) in the reaction medium to form the respective R x and generating an NI salt.

[0055] Depending on the target synthesis product, various organic compounds are synthesized using the organic cation R x N + As donors of R, i.e., as they dissociate in the reaction medium to give the respective organic cations R x N + , i.e. R4N + and R3N + may be used as a compound capable of forming a cation selected from the group:

[0056] Preferably, the organic cation R is a compound whose dissociation does not introduce additional and difficult to remove contamination into the reaction medium. x N + It is used as a donor.

[0057] R x Organic cations R by the method developed to prepare NI salts x N + Examples of compounds that can be used as donors include amines, preferably primary amines, preferably amines containing 1 to 8 carbon atoms in the molecule, such as methylamine (CH3NH2) to obtain methylammonium iodide (CH3NH3I), ethylamine (C2H5NH2) to obtain ethylammonium iodide (C2H5NH3I), or octylammonium iodide (C8H 17 Octylamine (CH) to obtain NHI 17 NH2) is an organic cation R4N +(i.e. x=4) donor. Thus, each amine can be dissociated to form the respective organic cation R4N, which is the substrate for salt synthesis. + results.

[0058] Furthermore, amidine acetates such as formamidine acetate are cations of the organic cation R + (i.e. x=3) (the ionic formula is [(HC(NH2)2] + [CH3COO] - ), because these compounds are readily soluble under the reaction conditions and the respective organic cations R + and the acetate anion, which is converted to acetic acid during the course of the reaction and can be evaporated from solution due to its low boiling point, and therefore can be easily removed from the mixture after the reaction.

[0059] The above-mentioned selection of the compound acting as the donor of the organic cation provides high purity of the synthesis product, i.e., the salt containing the iodide anion and the organic cation, and as a result, the salt R prepared using the developed method. x The quality of perovskite coatings fabricated with Ni is improved.

[0060] The reaction proceeds with the use of an organic cation R x N + Depending on the solubility of the donor, either molecular iodine (I2) (reactions shown in Figures 1A, 2A, 3A, and 4A) or iodine in its ionized form, I3 - (reactions shown in Figures 1B, 2B, 3B, and 4B) and the organic cation R used x N +The reaction may be carried out in a polar or non-polar medium using a variety of solvents that provide good solubility of the donor. In addition, the solvent should preferably allow the reaction to be carried out at a temperature higher than 50° C., so that, for example, the solvent should have a boiling point higher than 50° C., more preferably between 50 and 150° C. Solvents with a boiling point higher than 150° C. may be difficult to remove when washing the reaction product, and therefore such solvents may constitute an undesirable contamination and are less preferred to use.

[0061] For example, in an embodiment of the present disclosure with methylamine used as the donor of organic cation, the reaction can be carried out in a solvent such as water, methanol, ethanol, absolute ethanol (at a concentration of 99.8%, e.g. obtained by distillation with the addition of benzene, where a small amount of benzene can be removed during purification, so that contamination of the solvent with benzene does not adversely affect the final purity of the product), isopropanol, a mixture of a suitable alcohol and water, dioxane, tetrahydrofuran (THF), etc., and preferably, the reaction is carried out using absolute ethanol as a solvent, since absolute ethanol provides a relatively high solubility of the substrate, including the iodine molecule and the donor of organic cation, including methylamine. Furthermore, ethanol has a boiling point of 78°C, and therefore, the reaction can be carried out at a preferred temperature higher than 50°C. In addition, absolute ethanol is easily removable during purification of the reaction product.

[0062] With the increase in the number of carbon atoms in the molecule of the organic cation donor, the polar character of the molecule weakens in favor of the non-polar character of the molecule, hence solvents such as methanol, ethanol, isopropanol, absolute ethanol, dioxane, tetrahydrofuran (THF) etc. must be used instead of water.

[0063] For example, when octylamine or formamidine acetate is used as the donor of the organic cation, ethanol may be used as the solvent.

[0064] The introduction of the organic cation donor during the preparation of the reaction mixture is preferably accomplished at a temperature in the range of 0-30° C. For example, the addition of the organic cation donor may be accomplished at room temperature, since the reaction induced by such addition is inherently exothermic. After the organic cation donor compound is added, the reaction mixture is preferably heated to a temperature above 50° C. This ensures an increased reaction rate. At such temperature conditions, the reaction can be carried out with satisfactory product yields within a relatively short time, e.g., less than 2 hours.

[0065] 1A, 2A, 3A, and 4A show schematic diagrams of the respective reaction steps of the synthesis of iodide salts according to the developed method in the form of stoichiometric equations, where FIG. 1A shows the reaction steps of R x Generalized representation of reactions for the synthesis of NI iodides, while FIG. 2A shows the synthesis of methylammonium iodide (MAI), FIG. 3A shows the synthesis of octylammonium iodide (OAI), while FIG. 4A shows the synthesis of formamidinium iodide (FAI). In FIG. 1A, FIG. 2A, FIG. 3A, and FIG. 4A, reactions labeled with reference numbers 1 and 2 represent individual synthetic steps involving intermediate products, while reaction labeled with reference number 3 is a combination of reactions 1 and 2.

[0066] As illustrated in FIGS. 1A-4A, in the first synthetic step (reaction 1), formic acid (HCOOH) reacts with molecular iodine (I2) to produce hydrogen iodide (H + I - ), and the by-product carbon dioxide (CO2) which is released. The hydrogen iodide formed constitutes the source of iodide anions. The iodide ions (I - ) reacts with a compound that is an organic cation donor (reaction 2) to produce the reaction product, the respective organic cation R x This produces NI iodide.

[0067] The reaction is carried out with an excess of iodine (I2) relative to formic acid (HCOOH), where preferably an excess of iodine is used in the reaction in a molar ratio of 1.01(I2):1.0(HCOOH) to 2.0(I2):1.0(HCOOH), more preferably molecular iodine (II2) is used in excess in a molar ratio to formic acid of 1.01(I2):1.0(HCOOH) to 1.10(I2):1(HCOOH), most preferably in a molar ratio of 1.05(I2):1(HCOOH).

[0068] Molecular iodine excess relative to formic acid in the reaction medium provides for synthesis of the respective iodide salts with improved purity (superior).

[0069] A small excess of iodine (I2) relative to formic acid (HCOOH), but more preferably an excess of I2 in the ranges mentioned above relative to HCOOH, will act as a donor to convert the formate salt ([R x N + ][HCOO - ]) from forming in the reaction mixture. x N + ][HCOO -

[0036] is difficult to separate from the reaction products, and in some cases (for certain salts and certain products) impossible without expensive specialized purification methods. Therefore, it is beneficial to use molecular iodine in a moderate excess.

[0070] The use of an excess of molecular iodine relative to formic acid results in the production of by-products ([R x N + ][HCOO - ]), whereby the purity of the resulting product is necessarily improved by limiting the formation of difficult-to-remove salts ([R x N + ][HCOO - The most beneficial excess of iodine molecules, which significantly reduces the formation of reaction by-products, is 1.01 to 1.10 moles of I2 per mole of HCOOH.

[0071] Furthermore, the product needs to be purified to remove the iodine present in the reaction mixture, and if the excess iodine used is higher than indicated, the purification procedure may need to be repeated (recrystallization), which incurs additional costs due to the use of additional solvents, and also wastes time due to the use of additional solvents.

[0072] As a result, excess unreacted iodine and acetate ([R x N + ][HCOO - To prevent contamination of the final product with both reaction by-products in the form of iodine and iodine per mole of HCOOH, a preferred excess of iodine that may be used is 1.01 mole of I2 per mole of HCOOH, as such value provides an optimal high purity of the final product.

[0073] In addition, the reaction proceeds with an excess of organic cations (R x N + ) donor (examples of which are described above), and most preferred excesses of organic cation donor relative to molecular iodine are in the range of 1.01 to 1.50 moles of organic cation donor per mole of molecular iodine (I2). The use of excess organic cation donor provides the advantages described below. Among other things, the excess of organic cation (R x N + ) ensures the complete reaction of the in situ prepared hydrogen iodide (HI) with the organic cation. If the obtained HI remains in the reaction environment at the end of the reaction as a result of a molar shortage of the organic cation donor, this remaining acid HI may be oxidized to iodine oxoacids such as HIO, HIO2, HIO3, and HIO4, and as a result by-products (in the form of the respective salts) may be formed by anion exchange reactions between the iodine oxoacids and the reaction products. Such salts are very difficult to separate from the products, and the purity of the products (respective iodide salts) is lower. Therefore, in order to prevent an excess of the in situ prepared hydrogen iodide (HI) relative to the organic cation donor, an excess of the organic cation donor (R x N+ ) is used, which, as explained above, prevents contamination of the reaction products. In other words, an excess of organic cations (R x N + ) ensures improved purity of the product obtained. In addition, the organic cation (R x N + For embodiments according to the present disclosure in which the donor of ) is in gas or liquid state, unreacted excess of said compound can be readily separated from the reaction product using commonly known purification techniques.

[0074] In preparing the reaction mixture, an excess of organic cation (R x N + An additional advantage of providing donors of iodine (I2) is the relatively low price of the compounds mentioned (e.g. methylamine) compared to molecular iodine (I2), which means a reduction in the costs of preparing the respective iodides using the developed method.

[0075] Optionally, to achieve improved time efficiency, salt R x The reaction for the synthesis of NI may be carried out in the presence of a small amount of a catalyst, which is preferably a catalyst that is capable of reacting with the reaction product R x It is the same compound as NI iodide salt. The reactions involving the use of the respective catalysts are shown in FIG. 1B - as a general representation, and in FIG. 2B - synthesis of methylammonium iodide (MAI), FIG. 3B - synthesis of octylammonium iodide (OAI), and FIG. 4B - synthesis of formamidinium iodide (FAI) as exemplary embodiments. Thus, for example, to obtain methylammonium iodide (MAI) as a product, as shown in FIG. 2B, a small (catalytic) amount of MAI is mixed with iodine (I2) in a first step (reaction 1).

[0076] Thus, similar to the steps in the synthesis of the iodides MAI, OAI, and FAI, respectively, without a catalyst (Figures 2A, 3A, and 4A), reactions 1-3 in Figures 2B, 3B, and 4B show the individual steps in the synthesis of the products with the catalyst, showing the transition states and intermediate products, while reaction 4 is a compilation of reactions 1-3, the substrates, and the products.

[0077] As can be seen in Figures 1B, 2B, 3B, and 4B, in the first step (reaction 1), the catalyst, which is the respective iodide salt (preferably the same as that to be obtained), reacts with iodine (I2) to give the transition state triatomic iodine anion I3 - which then (reaction 2) reacts with formic acid to produce the respective iodide salt, in situ hydrogen iodide (HI), and carbon dioxide. Then (reaction 3), the resulting I - The iodide anion is an organic cation donor compound R x N + and react with each of the reaction products R x NI, produces iodide salt.

[0078] Compared to the solubility of molecular iodine (I2), which has a slightly lower tendency to react with formic acid in situ to obtain hydrogen iodide (HI), the solubility of I3 formed with the aid of a catalyst added to the reaction is - The ion features significantly improved solubility in polar solvents and reacts more readily with formic acid (HCOOH) to generate hydrogen iodide (HI) in situ, thus allowing for a faster reaction process with the addition of a catalyst (Figures 1B-4B, respectively).

[0079] The transition form of the triatomic iodine anion I3 - The formation of has an accelerating effect and the reaction with the presence of a catalyst can be carried out, for example, on an industrial or semi-technical scale, thus increasing the production capacity of said compound.

[0080] The addition of a catalyst reduces the reaction time by approximately 60-180 minutes. Thus, with the addition of a catalyst, the average reaction time is 20-120 minutes, whereas without a catalyst the average reaction time is 120-300 minutes.

[0081] An additional advantage of using a catalyst that is the same compound as the product of the reaction is that the purity of the product obtained is improved since the catalyst and the reaction product are the same compound, thereby the catalyst does not constitute a contamination of the product. However, iodide salts, preferably R, that are not the same compound as the product synthesized, are also useful. x The use of NI as a catalyst also increases the reaction rate.

[0082] Preferably, the catalyst is added to the system in an amount of 0.01 to 0.03 moles per mole of iodine (II2), i.e., in a molar ratio of 0.01 (moles of catalyst):1 (moles of I2) to 0.03 (moles of catalyst):1 (moles of I2). The reaction involving the presence of a catalyst is carried out at a temperature in the range of 0 to 80°C.

[0083] Thus, in MAI synthesis, MAI may preferably be used as a catalyst, in OAI synthesis, OAI may preferably be used as a catalyst, and in FAI synthesis, FAI may preferably be used as a catalyst.

[0084] R obtained using the developed method x Ni iodide salts feature improved product purity and are suitable for use as one of the precursor components of the respective perovskite in perovskite-forming compositions, such as perovskite inks for printing on various substrates, e.g., ITO, to prepare perovskite photoactive layers in photovoltaic cells.

[0085] R obtained using the method of the present invention in a perovskite-forming composition x The use of NI iodide, especially those used in photovoltaic devices in the photoactive layer, is particularly beneficial because it provides the resulting R xThis is because Ni iodide ensures the formation of a perovskite layer that exhibits improved morphology, leading to improved photoactive properties of the resulting perovskite layer.

[0086] Preferably, the resulting product (R x NI) is recrystallized to separate it from unreacted substrates used in the synthesis.

[0087] FIG. 6 shows the iodide R prepared using the method according to the present disclosure. x The exemplary reactions of perovskite synthesis from NI are shown. The resulting perovskite is suitable for use in photovoltaic cells as a photoactive layer. Reactions 1, 2, 3, 5, and 6 show synthesis in which one of the precursors of the perovskite is methylammonium iodide (MAI) prepared using the developed method, while the other precursor is iodide, bromide, or lead(II) chloride or tin(II) iodide, respectively. Reaction 4 represents synthesis in which one of the perovskite precursors is formamidinium iodide (FAI) prepared using the method according to the present disclosure, and the other perovskite precursor is lead(II) iodide.

[0088] Thus, the iodides prepared with the developed method can be used to obtain a variety of perovskites, including those used in photovoltaic devices, in particular for the photoactive layer.

[0089] Due to their high purity, the iodides obtained using the developed method are suitable for use in perovskite-forming compositions as precursor components of perovskite (e.g., according to the reaction in FIG. 6 ), including those in the form of colloidal solutions containing lead salts, lead halides, lead(II) iodide, lead(II) chloride, or lead(II) bromide, respectively, as other perovskite precursors.

[0090] In addition, it was found in the course of further research, the results of which are discussed below in the embodiments of the present invention, that a particularly advantageous perovskite-forming composition in the form of a colloidal solution, a composition containing an iodide salt obtained using the method developed, to which the added methylammonium dihydrogen phosphate(I) CH3NH3H2PO2, is particularly suitable, since the perovskite-forming layer obtained using this composition improves the parameters of the photovoltaic cell obtained therewith. EXAMPLES

[0091] Example I - Synthesis of methylammonium iodide (MAI) using MAI as a catalyst In a round bottom flask, a portion of the MAI catalyst was dissolved in ethanol and MAI was added in an amount of 0.01 moles for each mole of I2 iodine, resulting in a light translucent solution. To the resulting solution was then added all of the dark brown I2 iodine in a single step to obtain a brown non-translucent solution, thereby confirming the presence of iodine (I2) in the solution, which dissolved after 5 minutes, thereby forming I3 -It was shown that I2-iodine molecules were formed in the solution (otherwise I2-iodine molecules would dissolve at a much slower rate). Formic acid was then added to the resulting mixture in a molar ratio of 0.97:1.0 relative to I2-iodine in a single step, and no change was observed in the flask with the naked eye. Methylamine, a suitable organic cation donor, was then added to the solution. Methylamine was slowly dripped into the solution, totaling 2.6 moles of methylamine for each mole of I2-iodine, and added to the solution. Upon addition of methylamine, the formation of bubbles and effervescence of the flask contents was observed, indicating that CO2 gas was released from the reaction mixture. An increase in temperature was also observed during the reaction, indicating that the reaction was exothermic. Foam formation was observed only after the addition of methylamine, which can be explained by the fact that the reaction was accelerated by the use of hydrogen iodide (HI) generated in situ. After the addition of methylamine was completed, the brown mixture was heated for 1 hour while maintaining the temperature of the mixture at 80° C., after which the reaction was terminated. After 1 hour of heating, the mixture turned from brown to light brown, but the color of the mixture was not considered as an indication of the end of the reaction, which was attributed to the use of excess iodine relative to formic acid, preventing the conversion of the entire iodine (I2) content to hydrogen iodide (HI). The excess iodine used in the reaction prevented the formation of methylammonium formate as a by-product of the reaction. The resulting product was separated from the post-reaction mixture by evaporation of the solvent to obtain a tan powder, which was completely dissolved in boiling absolute ethyl alcohol (100%) and recrystallized. After cooling to room temperature, diethyl ether was added to the mixture to precipitate further product. The precipitate was filtered and washed with diethyl ether until the precipitate turned white. The resulting precipitate, which was the product of the reaction, i.e., MAI, was dried in vacuum (pressure lower than 0.2 mbar) for 5 hours, after which the product was weighed. A product (MAI) yield of 88% was obtained, compared to the theoretical yield according to the stoichiometry of the reaction. The composition of the resulting product was subjected to analysis which confirmed the absence of even trace amounts of phosphorus salts since no phosphorus donor was used at any step of the synthesis.

[0092] The resulting product was also tested for the presence of phosphorus and the results were compared with MAI prepared using methods known in the art and with commercially available MAI. The results are summarized in Table I.

[0093] Example II - Synthesis of Octylammonium Iodide (OAI) without Catalyst A portion of iodine (I2) was dissolved in ethanol in a round bottom flask in a single step to obtain a non-translucent dark brown solution indicating the presence of molecular iodine (I2). After 15 minutes, the iodine was dissolved in the ethanol and the solution remained dark brown and non-translucent. Formic acid was then added to the flask in a molar ratio of 0.97:1.0 HCOOH:I2 and no change was observed in the flask. 2.6 moles of octylamine per mole of I2 iodine were then slowly dripped into the solution. After each drop of octylamine was added, bubbles and foam were seen in the reaction solution and the temperature of the reaction mixture was observed to increase due to its exothermic process. The bubbles and foam indicated that the octylamine had reacted with hydrogen iodide HI generated in situ. After all the octylamine had been added (the reaction mixture remained brown), the flask was heated for 2 hours while maintaining the temperature of the reaction mixture at 80°C. The reaction was then terminated and the resulting mixture had a lighter brown color, but the color of the mixture was not considered an indication of the end of the reaction, which was due to the excess iodine (I2) used, which prevented the iodine from reacting completely. The use of an excess of iodine relative to formic acid prevented the formation of octylamine formate, which would have been a by-product of the synthesis, and therefore contamination of the resulting octylammonium iodide (OAI). Once the reaction was over, the mixture was evaporated on a rotary evaporator under a reduced pressure of 30 mbar, with the flask containing the solution placed in a water bath at a temperature of 50° C. during evaporation, resulting in a tan powder, which was then dissolved in boiling absolute ethanol and recrystallized in 1 mL of absolute ethanol per 1 g of expected product (the expected yield was 1 mL / 1 g). The solution was then cooled and diethyl ether was added to the cooled mixture to increase the precipitation efficiency. It was filtered to obtain a white precipitate, which was washed with diethyl ether until the precipitate was white. The resulting precipitate, constituting the reaction product (OAI), was dried in vacuum (pressure below 0.2 mbar) for 5 hours, after which the product was weighed. A product (OAI) yield of 76% was obtained, compared to the theoretical yield according to the stoichiometry of the reaction.

[0094] Example III - Synthesis of Formamidinium Iodide (FAI) without Catalysis A portion of iodine (I2) was dissolved in ethanol in a round bottom flask in a single step to obtain a non-translucent dark brown solution indicating the presence of molecular iodine (I2). After 15 minutes, the iodine was dissolved in the ethanol and the solution remained dark brown and non-translucent. 1.0 Eq (equivalent) of formic acid HCOOH (relative to iodine (I2)) was then added to the flask and no change was observed in the flask. Formamidine acetate (solid at room temperature) was then added to the solution in a single step with a total amount of 2.1 Eq (equivalent) of formamidine acetate (relative to iodine (I2)). After the addition of formamidine acetate (the reaction mixture remained brown), the flask was heated for 12 hours while maintaining the temperature of the reaction mixture at 50°C. The reaction was then terminated and the resulting mixture had a lighter brown color. Once the reaction was over, the mixture was evaporated on a rotary evaporator under a reduced pressure of 30 mbar, while the flask containing the solution to be evaporated was placed in a water bath at a temperature of 50° C., resulting in a yellow-brown powder which was then dissolved in boiling absolute ethanol and recrystallized in 1 mL of absolute ethanol per 1 g of expected product (the expected yield was 1 mL / 1 g). The solution was then cooled to room temperature and diethyl ether was added to the cooled mixture to increase the precipitation efficiency. It was filtered to obtain a white precipitate, which was washed with diethyl ether until the precipitate was white. The resulting precipitate, which constituted the reaction product (FAI), was vacuum dried (pressure lower than 0.2 mbar) for 5 hours, after which the product was weighed. A product (FAI) yield of 82% was obtained, compared to the theoretical yield according to the stoichiometry of the reaction.

[0095] The resulting product was also tested for the presence of phosphorus, and the results are summarized in Table I below. [Table 1]

[0096] Example IV - Preparation of a perovskite-forming composition in the form of an ink using MAI as a perovskite precursor The following compounds: - 305.14 mg of methylammonium iodide (MAI), prepared according to the procedure of Example I above, - 166.50 mg of anhydrous lead(II) acetate, Pb(CH3COO)2; - 35.58 mg of lead(II) chloride PbCl2 - 46 μL of a solution of methylammonium dihydrogen phosphate(I) CH3NH3H2PO2 in DMF at a concentration of 19.8 mg / mL (corresponding to 0.3% by weight of CH3NH3H2PO2 relative to the weight of MAI used) A perovskite-forming composition was prepared by dissolving in 954 μL of dimethylformamide (DMF).

[0097] The components were mixed for 12 hours, after which the resulting colloidal solution was filtered using a 0.45 μM filter to obtain a colloid with a dispersed phase of appropriate particle size.

[0098] The resulting composition had the form of a stable colloid suitable for printing (ink). No change in the particle size of the colloids and no tendency to aggregate were observed. During several weeks of observation, the composition remained in the form of a clear (semi-transparent) colloidal solution.

[0099] The resulting colloids (containing the single crystallized MAI) are shown in images I, II, III, and IV of Figure 14A, where the images show samples of the same colloid, where image I shows the colloid on the day of its preparation, image II shows the colloid 24 hours after its preparation, image III shows the colloid 96 hours after its preparation, and image IV shows the colloid 168 hours after its preparation, confirming that the transparency of the colloid has not changed over time. For comparison, Figures 14B, 14C, and 14D show images of colloids with the same composition, where Figure 14B shows an image of a colloid containing commercial MAI prepared in a conventional manner (without in situ generated HI), Figure 14C shows a colloid with MAI prepared using methods known in the art, a colloid containing MAI that had been recrystallized once, while Figure 14D shows a colloid with MAI obtained using methods known in the art, a colloid containing MAI that had been recrystallized thrice. Like FIG. 14A, FIG. 14B shows photographs I, II, III, and IV of the same colloid sample taken respectively as follows: I—the day of colloid preparation, II—24 hours, III—96 hours, and IV—168 hours after its preparation; FIG. 14C, I shows a photograph of the colloid taken on the day of colloid preparation, FIG. 14C, II—72 hours after said colloid preparation; similarly FIG. 14D, I—image of the colloid on the day of colloid preparation, FIG. 14D, II—photograph taken 72 hours after said colloid preparation, and FIG. 14D, III—photograph taken 144 hours after colloid preparation, illustrating the change over time in transparency of MAI-containing colloids prepared using methods known in the art, which is due to the presence of phosphorus salts in the colloids of FIG. 14B and FIG. 14C. It should be noted that there is no visible (to the naked eye) turbidity only for the colloid prepared from the thrice recrystallized MAI after 144 hours, which is also observed for the colloid prepared with the MAI of the present invention, but subjected to one recrystallization, further demonstrating the superior parameters of the iodide (MAI) prepared using the method of the present invention.

[0100] All photographs in Figures 14A, 14B, 14C, and 14D were taken with a flashlight shining on the colloids to demonstrate the Tyndall effect under the same lighting conditions. Thus, the studies conducted confirmed the improved stability over time of MAI-containing colloids prepared using the methods of the present invention (Figure 14A), as well as the overall improved transparency of the colloids.

[0101] Thus, a perovskite-forming composition prepared in the form of a colloidal solution contains the MAI of the present invention as one of the perovskite-forming components.

[0102] Example V - Preparation of Perovskite Coatings Using MAI The three perovskite-forming compositions are as follows: - composition I containing the same components as the perovskite-forming composition of example IV above, using MAI obtained by methods known in the art; Composition II containing the same components as the perovskite-forming composition of Example IV above, but without the addition of CH3NH3H2PO2; Composition III containing the same components as the perovskite-forming composition of Example IV above, where the MAI used is MAI obtained by the method according to the present disclosure, and CH3NH3H2PO2 is added. It was prepared as follows.

[0103] The substrates for the application of compositions I, II and III were then appropriately prepared as follows: plates were cut from PET / ITO (ethylene terephthalate / indium tin oxide) sheets using a laboratory punch, and then etched in 15% hydrochloric acid (HCl) solution by immersion to obtain the desired pattern on the ITO conductive layer. The etched plates were cleaned in an ultrasonic bath (cleaning solutions used: ion-exchanged water, isopropyl alcohol). The substrates thus prepared were air-dried at 95° C. for 1 hour, then PEDOT:PSS (Poly(3,4-ethylene-1,4-dioxythiophene:styrene polysulfonate) was applied onto the cleaned and dried substrates using a spin-coating method in air. The substrates were then heated at 95° C. for 45 minutes in air. Then, the respective perovskite-forming compositions: Composition I, Composition II, and Composition III were applied to the respective plates using a spin-coating method under a nitrogen atmosphere (inside a glove container). To crystallize the perovskite materials, the substrates coated with the respective perovskite-forming compositions: Composition I, Composition II, and Composition III films were heated at 96° C. for 15 minutes.

[0104] The resulting perovskite coating in the form of a thin film on the PEDOT / PET / ITO substrate was then examined under a scanning electron microscope (SEM) and the images shown in FIG. 7 were taken, where FIG. 7A is an SEM image of a perovskite coating prepared using composition I containing in its composition MAI prepared using known methods, FIG. 7B is an SEM image of a perovskite coating prepared using composition II containing in its composition MAI prepared using a method according to the present disclosure but without added CH3NH3H2PO2, while FIG. 7C is an SEM photograph of a perovskite coating prepared using composition III containing in its composition MAI prepared using a method according to the present disclosure and with added CH3NH3H2PO2.

[0105] The results of SEM analysis of the perovskite coatings prepared using compositions I, II, and III confirmed the improved morphology of the perovskite coatings prepared using MAI obtained using the method according to the present disclosure.

[0106] As shown in the photograph in Figure 7A, the perovskite layer (using the prior art MAI) is dense, i.e. does not contain any pinholes, and features small grains of perovskite material. The perovskite layer in Figure 7B prepared using the MAI obtained using the method according to the present disclosure features larger grains and improved crystallinity, which is beneficial for the operation of the battery, and pinholes are visible in the layer.

[0107] Here, the layer in Figure 7C prepared using MAI obtained by the method according to the present disclosure with CH3NH3H2PO2 added features larger grains and improved crystallinity, which is beneficial for the operation of the battery, and pinholes are visible in the layer. This may be achieved by adding CH3NH3H2PO2 in an amount of 0.3 wt% CH3NH3H2PO2 with respect to the weight of MAI, which allows adjusting the chemical parameters of the perovskite-forming composition, which is a colloidal solution, to obtain the optimal morphology of the perovskite layer.

[0108] The resulting coating was also analyzed using X-ray diffraction studies to obtain the diffractograms shown in FIG. 8, where FIG. 8A shows the diffraction of the CHNHPbI perovskite network, FIG. 8B shows the magnified peaks corresponding to the reflection (110) at the tetragonal plane of the perovskite phase, while FIG. 8C shows the magnified (control) peaks corresponding to the PET material, with negligible differences between the samples.

[0109] The thickness measured using an optical profilometer was the same for all coatings obtained with compositions I, II, and III, so the differences in the intensity of the peaks in the diffractograms are not due to different amounts of perovskite material between the samples. The obtained X-ray diffractograms showed a higher intensity of the peaks corresponding to the perovskite reflection positions for the samples with MAI (compositions II and III) prepared by the method according to the present disclosure, in particular the peak at 14° corresponding to the reflection (110) in the tetragonal symmetry of the perovskite material (FIG. 8B). This may be due to the formation of a higher occupancy of the crystalline phase and / or a higher degree of orientation of the perovskite grains, which is particularly beneficial for photosensitive perovskite coatings for optoelectronic applications and may provide improved functionality when the coatings are used in solar cells.

[0110] Example VI - Preparation of perovskite photovoltaic cells using MAI To prepare a photovoltaic cell having a photoactive perovskite layer, the composition, i.e. - composition I containing ingredients as in the perovskite-forming composition of Example IV above, using MAI obtained using methods known in the art; - composition II, containing ingredients as in the perovskite-forming composition of Example IV above, containing MAI (with in situ generated HI) according to the present disclosure, but without added CH3NH3H2PO2; - Composition III containing ingredients as in the perovskite-forming composition of Example IV above, the MAI used is MAI obtained by the method according to the present disclosure, and CH3NH3H2PO2 is added. The perovskite composition was prepared using

[0111] Using the above-mentioned compositions, photovoltaic cells with a simple sandwich architecture were prepared, including the following layers: PET / ITO / PEDOT:PSS / perovskite:CH3NH3PbI3 / PCBM / BCP / Ag.

[0112] For this purpose, substrates comprising respective layers of PET / ITO / PEDOT:PSS / perovskite:CH3NH3PbI3 were prepared for each cell individually from the perovskite-forming compositions I, II, and III described above.

[0113] Immediately after the perovskite layer was obtained, a PCBM (phenyl-C61-butyric acid methyl ester) solution dissolved in anhydrous chlorobenzene at a concentration of 20 mg / mL was deposited on the perovskite layer of each cell using a spin-coating method under nitrogen (inside a glove box). For each cell, the deposited PCBM layer was heated at 60° C. for 10 minutes.

[0114] Then, a layer of 5 nm BPC (bathocuproine) and 90 nm silver (Ag) was added at 1·10 -6 They were thermally evaporated one by one at a given pressure of mbar.

[0115] The characteristics of the resulting cells are shown in Figure 9A, which shows the results of cell efficiency (η) measurements, which determine the energy conversion efficiency of the cell as a function of the type of perovskite-forming compositions I, II, and III for the cell's perovskite layer. The results confirm the improved efficiency of the cell with the perovskite layer of perovskite composition II with the MAI of the present invention compared to the cell containing the perovskite layer of composition I with the MAI of the prior art, and show a further significant improvement in the efficiency of the cell with the perovskite layer of composition III with the MAI of the present invention and the addition of CH3NH3H2PO2.

[0116] On the other hand, FIG. 9B is a summary of test results showing the dependence: current density-voltage, which also confirms the improved parameters of the cells with perovskite layers made with compositions II and III containing MAI obtained by the method of the present disclosure. As shown in the graph of FIG. 9B, the average efficiency of the cells with perovskite layers of composition II is 8.2%, while the efficiency of the cells with perovskite layers of composition I of the prior art ranges from 7.2 to 8.0%, which represents an improvement in cell efficiency at the level of 2.5 to 14%. The cells with perovskite layers made with composition III (containing MAI and CH3NH3H2PO2 according to the present disclosure) showed a further increase in efficiency with respect to both the cells with composition I and the cells with composition II. The efficiency of the cells with composition III ranges from 9.0 to 9.2%.

[0117] Furthermore, it was found that during the course of operation, compared with a cell having a perovskite layer made with composition I containing MAI of the prior art, cells having perovskite layers made with compositions II and III exhibited improved reproducibility and long-term stability of operation, which is attributed to the difference in the density of defects in the perovskite layers of compositions I, II, and III, respectively.

[0118] Additionally, selected batteries were subjected to degradation tests at 800 W / m in an inert atmosphere. 2 and degradation at a temperature of 32° C. The results of these tests, summarized in FIG. 10, show that cells containing perovskite layers with the MAI of the present invention exhibit good performance over extended periods of time. In particular, the use of the MAI provided by the present disclosure allows for greater control over the quality of the resulting perovskite layer, including in particular a higher crystallinity of the perovskite layer, which may result in improved stability of cells made with such perovskites.

[0119] Example VII - Preparation of perovskite-forming compositions using FAI The following compounds: - 95.01 mg of formamidinium iodide (FAI), prepared according to the procedure of Example III above, - 38.53 mg of methylammonium bromide CH3NH3Br, - 274 mg of lead(II) iodide PbI2 - 2M solution of cesium iodide (CsI) in toluene A perovskite-forming composition was prepared by dissolving in a mixture of 400 μL of dimethylformamide (DMF) and 100 μL of dimethylsulfoxide (DMSO).

[0120] The components were mixed for 12 hours, after which the resulting colloidal solution was filtered using a 0.45 μM filter to obtain a colloid with a dispersed phase of appropriate particle size.

[0121] The resulting composition had the form of a stable colloid. No change in the particle size of the colloid and no tendency to aggregate was observed (as is the case for colloids containing FAI of the prior art). During the observation period of several weeks, the composition had the form of a clear (semi-transparent) colloidal solution.

[0122] Thus, the perovskite-forming composition prepared in the form of a colloidal solution contains the FAI of the present invention as one of the perovskite-forming components (perovskite precursor).

[0123] Example VIII - Preparation of perovskite coatings using FAI The two perovskite-forming compositions are referred to below: - composition I, containing the same components as the perovskite-forming composition of Example VII above, but using FAI obtained by methods known in the art; - Composition II containing the same components as the perovskite-forming composition of Example VII above, but containing FAI prepared by a method according to the present disclosure. It was prepared as follows.

[0124] The substrates were then prepared for depositing compositions I and II as described in Example V above. A layer of PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine]) in toluene was then applied onto the plate by spin-coating a PTAA toluene solution (concentration of 2 mg / mL, solution filtered using a 0.2 μm filter). Composition I (control) and composition II were then applied onto the substrate, respectively, under nitrogen using a spin-coating method with the following given parameters: spin time: 30 s, acceleration: 2500 rpm, rotation speed: 2500 rpm. During the last 8 s of coating, ethyl acetate (as anti-solvent) was dropped onto the film being prepared in an amount of 1000 μL per plate. The film was then heated at 100° C. for 40 min to obtain a perovskite structure.

[0125] The resulting perovskite coating in the form of a thin film on the substrate was then examined under a scanning electron microscope (SEM) and the images shown in FIG. 11 were taken, where FIG. 11A is an SEM image of a perovskite coating prepared with composition I containing in its composition an FAI prepared using a known method, while FIG. 11B is an SEM image of a perovskite coating prepared with composition II containing in its composition an FAI prepared using a method according to the present disclosure.

[0126] The results of SEM analysis of the perovskite coatings prepared with compositions I and II confirmed the good morphology of the perovskite coatings prepared with the FAI obtained using the developed method. The images show larger grains of the perovskite material obtained from the FAI of the present invention compared to the perovskite prepared with the prior art FAI.

[0127] The resulting coating was also analyzed using X-ray diffraction testing to obtain the diffractograms shown in FIG. 12, where FIG. 12A shows the diffraction pattern of the resulting perovskite Cs 0,1 (FA 0,83 MA 0,17 ) 0,9 Pb(I0,84 Br 0,16 12A shows the diffraction of a network of 3, where MA is a methylammonium moiety and FA is a formamidinium moiety, and FIG. 12B shows the zoomed-in peak corresponding to the (100) reflection of the cubic perovskite phase.

[0128] The thickness measured using the optical profilometer was the same for all coatings obtained with compositions I and II, so the difference in the intensity of the peaks in the diffractograms is not caused by different amounts of perovskite material between the samples. The obtained X-ray diffractograms showed a higher intensity of the perovskite reflection positions, especially the peak corresponding to (100) in the cubic perovskite phase, for the sample with FAI according to the method disclosed herein (composition II) (FIG. 9B). This may be due to the formation of a higher occupancy of the crystalline phase and / or a higher degree of orientation of the perovskite grains, which is particularly beneficial for photosensitive perovskite coatings for optoelectronic applications.

[0129] Example IX - Preparation of Perovskite Photovoltaic Cell Using FAI To fabricate a photovoltaic cell having a perovskite photoactive layer, a perovskite composition was prepared using the ingredients as in Example VIII above containing an FAI according to the present disclosure (Composition II - HI prepared in situ).

[0130] Using the composition as described above, the following layers were formed: PET / ITO / PTAA / Perovskite:Cs 0,1 (FA 0,83 MA 0,17 ) 0,9 Pb(I 0,84 Br 0,16 A photovoltaic cell with a simple sandwich architecture was prepared, including ZnO / PCBM / BCP / Ag.

[0131] For this purpose, a substrate containing layers of PET / ITO / PTAA / perovskite was prepared. 0,1 (FA 0,83MA 0,17 ) 0,9 Pb(I 0,84 Br 0,16 )3.

[0132] The respective PCBM, BCP, and Ag layers were then applied using the same methods as described in Example VI.

[0133] [Item 1] General formula R x A method for obtaining a salt having a NI, comprising the steps of: R x N is an organic cation (R x N + ) and R is an organic substituent R 1 -, R 2 -, R 3 represents a substituent (R-) independently selected from the group consisting of -, and hydrogen (H-); x is the organic cation R x N + is the number of said substituents R- directly bonded to the nitrogen (N) atom in the formula (I), and x is 3 or 4; I is the iodide anion (I - ) and The method comprises: synthesizing hydrogen iodide (HI) in situ by mixing molecular iodine (I2) and formic acid (COOH) in a solvent medium in a molar ratio of molecular iodine (I2):formic acid (COOH) of 1.01:1 or greater; The organic cation R x N + The organic cation R x N + in an amount to provide a molar ratio of donor:molecular iodine (I2); General formula R x maintaining the reaction mixture at a temperature of 20° C. or greater for a period of time necessary to obtain a reaction product that is the salt having an NI; having preparing a reaction mixture, method.

[0134] [Item 2] The organic cation R x N + The donor of R is independently selected from the group consisting of linear or branched alkyl substituents containing 1 to 8 carbon atoms in the substituted molecule and optionally containing at least one heteroatom replacing a carbon or hydrogen atom in the substituted molecule. 1 -, R 2 - and optionally R 3 The method of claim 1, wherein the heteroatom contains an - moiety as an organic substituent and the heteroatom is selected from the group consisting of silicon, oxygen, nitrogen, sulfur, iodine, chlorine, and bromine.

[0135] [Item 3] Iodine molecules (I2) are mixed with formic acid (HCOOH) in a molar ratio of iodine molecules (I2):formic acid (COOH) of 1.01:1 to 1.1:1, and the organic cation R x N + The donor is the organic cation R x N + 3. The method according to claim 1 or 2, wherein the donor is introduced into the solvent medium in an amount that gives a molar ratio of donor:molecular iodine (I2).

[0136] [Item 4] The method of any one of the preceding items, wherein molecular iodine (I2) is mixed with formic acid (HCOOH) in a molar ratio of 1.01:1 iodine (I2):formic acid (COOH).

[0137] [Item 5] The method of any one of the preceding items, wherein the reaction mixture is heated to a temperature in the range of 20 to 80° C.

[0138] [Item 6] The organic cation R x N + The method according to any one of the preceding items, wherein the donor is introduced into the solvent medium following in situ synthesis of hydrogen iodide (HI).

[0139] [Item 7] The amine is the organic cation R x N + and the resulting salt (R x NI) is an alkylammonium cation (R(H3)N + ), dialkylammonium cation R2(H2)N + , and trialkylammonium cations (R(H)N + an organic cation (R x N + The method of any one of the preceding items, comprising:

[0140] [Item 8] Primary alkylamines having the general formula RNH2 are substituted with the organic cation R x N + and the resulting salt, alkyl ammonium iodide, has the general formula R(H3)NI, where the substituent R represents an alkyl moiety containing 1 to 8 carbon atoms.

[0141] [Item 9] Methylamine is the organic cation R x N + and methylammonium iodide (MAI) is obtained as a salt.

[0142] [Item 10] Octylamine is the organic cation R x N + and octylammonium iodide (OAI) is obtained as a salt.

[0143] [Item 11] The amidine salt is the organic cation R x N + It is used as a donor for amidinium iodide (R2N-(R 3 7. The method according to any one of items 1 to 6, wherein C=N(H2)I) is obtained as a salt.

[0144] [Item 12] Formamidine acetate is the organic cation R x N + and formamidinium iodide (FAI) (H2N-C(H)=N(H2)I) is obtained as a salt.

[0145] [Item 13] The method of any one of the preceding items, wherein the solvent medium comprises at least one compound selected from the group consisting of methanol, ethanol, absolute ethanol, isopropanol, dioxane, tetrahydrofuran (THF), and dimethylformamide (DMF).

[0146] [Item 14] 10. The method of claim 9, wherein the solvent medium is water.

[0147] [Item 15] The step of preparing a reaction mixture comprises adding to the solvent medium a compound of the general formula R x The method of any one of the preceding items, further comprising the step of introducing a catalyst, the salt having a NI.

[0148] [Item 16] The catalyst is the reaction product, the salt R x Item 16. The method according to item 15, wherein the compound is the same as NI.

[0149] [Item 17] Item 17. The method according to item 16, wherein the catalyst is obtained by the method according to any one of items 1 to 14.

[0150] [Item 18] 18. The method according to any one of items 15 to 17, wherein the catalyst is introduced in a molar ratio of catalyst:molecular iodine (I2) ranging from 0.01:1 to 0.03:1.

[0151] [Item 19] As a base material in the synthesis of perovskite, a compound of general formula R prepared by the method according to any one of items 1 to 18 x Use of salts having NI.

[0152] [Item 20] A compound of general formula R obtained by the method according to any one of items 1 to 18. x A perovskite-forming composition comprising a salt having a Ni.

[0153] [Item 21] ammonium iodide (MAI), ethyl ammonium iodide, propyl ammonium iodide, butyl ammonium iodide, pentyl ammonium iodide, hexyl ammonium iodide, heptyl ammonium iodide, octyl ammonium iodide (OAI), and formamidinium iodide (FAI) x 21. The perovskite-forming composition of item 20, comprising said salt having a Nl.

[0154] [Item 22] 22. The perovskite-forming composition of item 21, further comprising at least one lead salt and at least one solvent.

[0155] [Item 23] 23. The perovskite-forming composition according to any one of items 20 to 22, further comprising methylammonium dihydrogen phosphate(I) CH3NH3H2PO2.

[0156] [Item 24] 24. The perovskite-forming composition according to item 23, comprising the following compounds, methylammonium iodide (MAI), anhydrous lead(II) acetate (CHCOO)Pb, and lead(II) chloride PbCl2, in amounts effective for the synthesis of perovskite from said compounds, and dimethylformamide (DMF) as a solvent, and ammonium methyl dihydrogen phosphate(I) CHNHHPO2 in an amount of 0.3% by weight relative to the weight of methylammonium iodide (MAI) contained in the composition.

[0157] [Item 25] 22. The perovskite-forming composition of claim 21, comprising formamidinium iodide (FAI), methylammonium bromide CH3NH3Br, lead (II) iodide PbI2, and cesium iodide (CsI) in amounts effective for the synthesis of a perovskite from said compounds.

[0158] [Item 26] A compound of general formula R obtained by the method according to any one of items 1 to 16. x A photovoltaic cell comprising a perovskite layer prepared using a salt having Ni.

[0159] [Item 27] 27. The photovoltaic cell according to item 26, comprising a perovskite layer obtained from the perovskite-forming composition according to any one of items 20 to 25.

Claims

1. General formula R ｘ A method for obtaining a salt having an NI, comprising the steps of: - R ｘ N is an organic cation (R ｘ N ＋ ) and R is an organic substituent R １ -, R ２ -, R ３ represents a substituent (R-) independently selected from the group consisting of -, and hydrogen (H-); - x is the organic cation R ｘ N ＋ is the number of said substituents R- directly bonded to the nitrogen (N) atom in the formula (I), and x is 3 or 4; - I is the iodide anion (I － ) and The method comprises: - Molecular iodine (I) in a solvent medium ２ ) and formic acid (HCOOH) in a ratio of 1.01:1 or more ２ synthesizing hydrogen iodide (HI) in situ by mixing hydrogen iodide (HI) and formic acid (HCOOH) in a molar ratio of 0.1:0.2; - adding an organic cation R ｘ N ＋ and a compound which is a donor of the organic cation R ｘ N ＋ Donor: Iodine molecule (I ２ ) in an amount that gives a molar ratio of 0.1 to 0.25 moles of R x N + , wherein the donor of organic cation R x N + contains as organic substituents R 1 -, R 2 -, and optionally R 3 - moieties independently selected from the group consisting of linear or branched alkyl substituents containing 1 to 8 carbon atoms, or substituents in which a carbon atom of the linear or branched alkyl substituent is substituted with at least one substituent containing at least one heteroatom, wherein the heteroatom is selected from the group consisting of oxygen, nitrogen, sulfur, iodine, chlorine, and bromine; - General formula R ｘ maintaining the reaction mixture at a temperature of 20° C. or greater for a period of time necessary to obtain a reaction product which is said salt with NI; preparing a reaction mixture having the steps of: The amine is the organic cation R ｘ N ＋ and the resulting salt (R ｘ NI) is an alkyl ammonium cation (R(H ３ ) N ＋ ), dialkylammonium cation R ２ (H ２ ) N ＋ , trialkylammonium cation (R ３ (H)N ＋ ), and cations in which a carbon atom of these cations is substituted with at least one substituent containing at least one heteroatom. ｘ N ＋ ) or Alternatively, formamidine acetate may be converted to formamidinium iodide (FAI) (H ２ NC(H)=N(H ２ ) to obtain I), ｘ N ＋ Used as a donor of method.

2. Iodine molecule (I ２ ) is a mixture of formic acid (HCOOH) and iodine (I) in a ratio of 1.01:1 to 1.1:

1. ２ ) (HCOOH) in a molar ratio of 0.1 to 0.2; ｘ N ＋ The donor is a 1.01:1 to 1.50:1 ratio of said organic cation R ｘ N ＋ Donor: Iodine molecule (I ２ ) into the solvent medium in an amount that provides a molar ratio of organic cation R ｘ N ＋ is introduced into the solvent medium following in situ synthesis of hydrogen iodide (HI) and the reaction mixture prepared is heated to a temperature in the range of 20-80°C.

3. The organic cation R used ｘ N ＋ 3. The method according to claim 1 or 2, wherein the donor of is selected from the group consisting of methylamine to obtain methylammonium iodide (MAI) or octylamine to obtain octylammonium iodide (OAI).

4. 4. The method of any one of claims 1 to 3, wherein the solvent medium comprises at least one compound selected from the group consisting of methanol, ethanol, absolute ethanol, isopropanol, dioxane, tetrahydrofuran (THF), dimethylformamide (DMF) and water.

5. The step of preparing a reaction mixture comprises adding the reaction product, the salt R ｘ 5. The method of any one of claims 1 to 4, further comprising the step of introducing a catalyst which is the same compound as NI.

6. The process according to claim 5, wherein the catalyst is obtainable by the process according to any one of claims 1 to 4.

7. The catalyst may be in the range of 0.01:1 to 0.03:1 catalyst: molecular iodine (I ２ 7. The method according to claim 5 or 6, wherein the aryl group is introduced in a molar ratio of 0.1 to 0.5.

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