Ionic liquid perovskite device

Abstract

A method comprising: forming a lead halide precursor ink comprising a Group 1 metal halide, a lead halide, an ionic liquid, and a solvent; depositing the lead halide precursor ink on a substrate; drying the lead halide precursor ink to form a lead halide film; and annealing the lead halide film.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 339,837, entitled “Ionic Liquid Perovskite Device,” filed on May 9, 2022, and U.S. Provisional Patent Application No. 63 / 339,337, entitled “Ionic Liquid Perovskite Device,” filed on May 6, 2022, the entire contents of which are incorporated herein by reference. Background Art

[0003] The use of photovoltaics (PV) to generate electricity from solar energy or radiation can provide many benefits including, for example, a power source, low or zero emissions, grid-independent electricity production, durable physical structure (no moving parts), stable and reliable systems, modular construction, relatively quick installation, safe manufacture and use, and good public opinion and acceptance for use. Summary of the invention

[0004] According to certain embodiments, a method includes: forming a lead halide precursor ink comprising a Group 1 metal halide, a lead halide, an ionic liquid, and a solvent; depositing the lead halide precursor ink on a substrate; drying the lead halide precursor ink to form a lead halide film; and annealing the lead halide film. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Figure 1 is a schematic diagram illustrating components of a photovoltaic device according to some embodiments of the present invention.

[0006] Figure 2 X-ray diffraction patterns of perovskite materials according to some embodiments of the present invention are shown.

[0007] Figure 3 Current-voltage (IV) and current density-voltage (JV) scans of perovskite material photovoltaic devices according to some embodiments of the present invention are shown.

[0008] Figure 4 Current-voltage (IV) and current density-voltage (JV) scans of perovskite material photovoltaic devices according to some embodiments of the present invention are shown.

[0009] Figure 5 Current-voltage (IV) and current density-voltage (JV) scans of perovskite material photovoltaic devices according to some embodiments of the present invention are shown.

[0010] Figure 6 Current-voltage (IV) and current density-voltage (JV) scans of perovskite material photovoltaic devices according to some embodiments of the present invention are shown.

[0011] Figure 7 Current-voltage (IV) sweeps and additional test data of perovskite material photovoltaic devices according to some embodiments of the present invention are shown.

[0012] Figure 8 is a graphical representation of X-ray diffraction peaks (XRD) spectra and UV-visible spectra of perovskite devices fabricated with or without ionic liquids according to some embodiments of the present invention.

[0013] Fig. 9 Scanning electron microscope images are shown comparing perovskite devices fabricated with and without ionic liquids according to some embodiments of the present invention.

[0014] Fig.10 Scanning electron microscope images are shown comparing perovskite devices fabricated with and without ionic liquids according to some embodiments of the present invention.

[0015] Fig.11 Scanning electron microscope images are shown comparing perovskite devices fabricated with and without ionic liquids according to some embodiments of the present invention.

[0016] Fig.12 Structural illustrations of certain organic molecules that can function as cations of ionic liquids according to some embodiments of the present invention are provided.

[0017] Fig.13 Structural illustrations of certain organic molecules that can serve as anions of ionic liquids according to some embodiments of the present invention are provided.

[0018] Fig.14 Current density-voltage (JV) scans of perovskite material photovoltaic devices according to some embodiments of the present invention are shown.

[0019] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The features and advantages of the present invention will be readily apparent to those skilled in the art. Although numerous modifications may be made by those skilled in the art, such modifications are within the spirit of the present invention.

[0021] Improvements in multiple aspects of PV technology that are compatible with organic, non-organic, and / or hybrid PV are expected to further reduce the cost of organic and other PV. For example, some solar cells such as perovskite PV solar cells can utilize novel cost-effective and high-stability alternative components such as nickel oxide interfacial layers. In addition, various types of solar cells can advantageously include chemical additives and other materials that, among other advantages, can be more cost-effective and durable than currently existing conventional options.

[0022] The present invention generally relates to compositions of matter, devices and methods of use of materials in photovoltaic cells that generate electrical energy from solar radiation. More specifically, the present invention relates to photoactive and other compositions of matter, and devices, methods of use and formation of such compositions of matter.

[0023] Some or all of the materials according to some embodiments of the present invention may also be advantageously used in any organic or other electronic device, some examples of which include, but are not limited to: batteries, field effect transistors (FETs), light emitting diodes (LEDs), nonlinear optical devices, transistors, ionizing radiation detectors, memristors, capacitors, rectifiers, and / or rectennas.

[0024] In some embodiments, the present invention can provide PV and other similar devices (e.g., batteries, hybrid PV cells, multi-junction PV, FETs, LEDs, X-ray detectors, gamma-ray detectors, photodiodes, CCDs, etc.). In some embodiments, such devices may include improved active materials, interfacial layers (IFLs), and / or one or more perovskite materials. Perovskite materials can be incorporated into each of one or more aspects of PV or other devices. According to some embodiments, the perovskite material may have the general formula CMX3, wherein: C includes one or more cations (e.g., amines, ammonium, phosphonium, Group 1 metals, Group 2 metals, and / or other cations or quasi-cation compounds); M includes one or more metals (examples include Be, Mg, Ca, Sr, Ba, Fe, Cd, Co, Ni, Cu, Ag, Au, Hg, Sn, Ge, Ga, Pb, In, Tl, Sb, Bi, Ti, Zn, Cd, Hg, and Zr); and X includes one or more anions. Perovskite materials according to various embodiments are discussed in more detail below.

[0025] Photovoltaic cells and other electronic devices

[0026] Some PV implementation plans can be found in Figure 1 . According to some embodiments, the exemplary PV structure may be substantially in the form of substrate-anode-IFL-active layer-IFL-cathode. The active layer of some embodiments may be photoactive, and / or it may include photoactive materials. Other layers and materials may be used in cells known in the art. In addition, it should be noted that the use of the term "active layer" is in no way intended to explicitly or implicitly limit or otherwise define the properties of any other layer. For example, in some embodiments, either IFL or both IFLs may also be active because they may be semiconducting in nature. Specifically, reference is made to Figure 1, depicting a stylized generic PV cell 1000 showing the high interfacial properties of some layers within the PV. PV 1000 represents a generic construction that may be applicable to several PV devices, such as perovskite material PV embodiments. PV cell 1000 includes a transparent substrate layer 1010, which may be glass (or a similar material that is transparent to solar radiation), which allows solar radiation to pass through the layer. The transparent layer of some embodiments may also be referred to as a superstrate or substrate, and it may include any one or more of a variety of rigid or flexible materials, such as: glass, polyethylene, polypropylene, polycarbonate, polyimide, PMMA, PET, PEN, Kapton or quartz. In general, the term "substrate" is used to refer to the material on which the device is deposited during manufacturing. Photoactive (PAM) layer 1040 may be composed of: an electron donor or p-type material, and / or an electron acceptor or n-type material, and / or an ambipolar semiconductor that exhibits p-type material properties and n-type material properties, and / or an intrinsic semiconductor that exhibits neither n-type properties nor p-type properties. In some embodiments, the photoactive layer 1040 can be a perovskite material as described herein. Figure 1 The photoactive layer 1040 is depicted as being sandwiched between two conductive electrode layers 1020 and 1060. Figure 1 In the embodiment, the electrode layer 1020 can be a transparent conductor, such as tin-doped indium oxide (ITO material) or other materials described herein. In other embodiments, the second substrate 1070 and the second electrode 1060 can be transparent. As previously described, the active layer of some embodiments does not have to be photoactive, although in Figure 1 In the device shown in FIG. 100 , it is photoactive. Electrode layer 1060 may be an aluminum material or other metal, or other conductive material such as carbon. Other materials may be used as known in the art. Battery 1100 also includes Figure 1 The IFL 1030 shown in the example of FIG. 1030 can facilitate charge separation. In other embodiments, the IFL 1030 can include multiple layers of IFL. For example, a perovskite material device can contain zero, one, two, three, four, five, or more interfacial layers (such as those of U.S. Pat. No. 11,171,290, the entire contents of which are incorporated herein by reference). Figures 2 to 4 There may also be an IFL 1050 adjacent to electrode 1060. In some embodiments, the IFL 1050 adjacent to electrode 1060 may also or alternatively include multiple layers of IFLs. In some embodiments, the IFL on the cathode side of the device (e.g. Figure 1 The IFL 1050 shown) may be p-type, and the IFL on the anode side of the device (eg Figure 1The IFL 1030 shown may be n-type. However, in other embodiments, the cathode side IFL may be n-type and the anode side IFL may be p-type. The battery 1100 may be attached to wires and discharge units such as batteries, motors, capacitors, electric grids, or any other electrical loads by electrodes 1060 and 1020. Additional embodiments of devices that may be used in accordance with the present invention may be found in U.S. Pat. Nos. 9,425,396 and 11,186,495 and U.S. Pat. Publication No. 2018 / 0301288, the entire disclosures of which are incorporated herein by reference.

[0027] Various embodiments of the present invention provide improved materials and / or designs in various aspects of solar cells and other devices, including, among others, active materials (including hole transport layers and / or electron transport layers), interfacial layers, and overall device design.

[0028] Perovskite materials

[0029] Perovskite materials may be incorporated into one or more aspects of PV or other devices. According to some embodiments, the perovskite material may have the general formula C w M y X z , wherein: C comprises one or more cations (e.g., amines, ammonium, phosphonium, Group 1 metals, Group 2 metals, and / or other cations or quasi-cation compounds); M comprises one or more metals (examples include Be, Mg, Ca, Sr, Ba, Fe, Cd, Co, Ni, Cu, Ag, Au, Hg, Sn, Ge, Ga, Pb, In, Tl, Sb, Bi, Ti, Zn, Cd, Hg, and Zr); X comprises one or more anions; and w, y, and z represent real numbers from 1 to 20. In some embodiments, C may comprise one or more organic cations. In some embodiments, each organic cation C may be larger than each metal M, and each anion X may be capable of combining with both the cation C and the metal M.

[0030] In certain embodiments, C may include ammonium, the general formula [NR4] +The organic cation, wherein the R groups can be the same or different groups. Suitable R groups include, but are not limited to: hydrogen, methyl, ethyl, propyl, butyl, pentyl or their isomers; any cyclic, branched or linear alkane, alkene or alkyne CxHy, wherein x = 1-20, y = 1-42; alkyl halide CxHyXz, x = 1-20, y = 0-42, z = 1-42, X = F, Cl, Br or I; any aromatic group (e.g., phenyl, alkylphenyl, alkoxyphenyl, pyridine, naphthylene); cyclic complexes containing at least one nitrogen in the ring (e.g., pyrrole, pyrrolidine, piperidine, tetrahydroquinoline, 2-hexahydropyrimidin-2-ylidenehexahydropyrimidine, octahydropyrazino[2,3-b]pyrazine, pyrazine, pyridine, pyrrol ... any sulfur-containing group (e.g., sulfoxide, thiol, alkyl sulfide); any nitrogen-containing group (nitrogen oxide, amine); any phosphorus-containing group (phosphate / ester); any boron-containing group (e.g., boric acid); any organic acid (e.g., acetic acid, propionic acid), and their ester or amide derivatives; any amino acid (e.g., glycine, cysteine, proline, glutamic acid, arginine, serine, histidine, 5-ammonium valeric acid), including α, β, γ and higher derivatives; any silicon-containing group (e.g., siloxane); and any alkoxy group or group -OCxHy, where x = 0-20 and y = 1-42.

[0031] In certain embodiments, C may include formamidine, the general formula [R2NCRNR2] + The organic cation wherein the R groups may be the same or different groups. Suitable R groups include, but are not limited to, any of the R groups listed in the preceding paragraphs.

[0032]

[0033] Formula 1 shows a compound having the general formula [R2NCRNR2] as described above. + Formula 2 shows exemplary structures of several formamidinium cations that can serve as cation "C" in perovskite materials.

[0034]

[0035] In certain embodiments, C may comprise a guanidine salt, of the general formula [(R2N)2C=NR2] + The organic cation, wherein the R groups can be the same or different groups. Suitable R groups include but are not limited to any R groups listed above in the preceding paragraphs.

[0036]

[0037] Formula 3 shows a compound having the general formula [(R2N)2C=NR2] as described above. +Formula 4 shows examples of the structures of several guanidinium cations that can serve as the cation "C" in the perovskite material.

[0038]

[0039]

[0040] In certain embodiments, C may include an ethylenetetramine cation of the general formula [(R2N)2C=C(NR2)2] + An organic cation, wherein the R groups may be the same or different groups.

[0041] Suitable R groups include, but are not limited to, any of the R groups listed above in the preceding paragraph.

[0042]

[0043] Formula 5 shows a compound having the general formula [(R2N)2C=C(NR2)2] + Formula 6 shows examples of the structures of several ethylenetetramine ions that can serve as the cation "C" in the perovskite material.

[0044]

[0045] In certain embodiments, C may include an imidazolium cation of the general formula [CRNRCRNRCR] + An aromatic cyclic organic cation wherein the R groups may be the same or different groups. Suitable R groups may include, but are not limited to, any of the R groups listed above in the preceding paragraphs.

[0046]

[0047] Formula 7 shows a compound having the general formula [CRNRCRNRCR] as described above. + Structure of the imidazolium cation.

[0048] In some embodiments, X may include one or more halides. In certain embodiments, X may alternatively or additionally include a Group 16 anion. In certain embodiments, a Group 16 anion may be an oxide ion, a sulfide ion, a selenium ion, or a tellurium ion. In certain embodiments, X may be F, Cl, Br, I, SCN, CN, or any other pseudohalogen. Other acceptable non-halogen anions may include, but are not limited to, nitrate, nitrite, carboxylate, acetate, acetonyl, pyruvate, formate, oxalate, sulfate, sulfite, thiosulfate, phosphate, tetrafluoroborate, hexafluorophosphate, tetrakis(perfluorophenyl)borate, hydrogen, oxygen, peroxide, hydroxide, nitrogen, arsenate, arsenite, perchlorate, carbonate, bicarbonate, chromate, dichromate, iodate, bromate, chlorate, chlorine, acid, hypochlorite, hypobromite, cyanate, cyanate, isocyanate, fulminate, thiocyanate, isothiocyanate, azide, tetracarbonylcobaltate, carbamoyldicyanomethanide, dicyanonitrosomethanide, dicyanamide, tricyanomethanide, amide, and permanganate.

[0049] By way of explanation, and without implying any limitation, the following discussion is of the formula C w M y X z In one embodiment, the perovskite material may comprise the empirical formula CMX3, wherein: M comprises one of the above metals, C comprises one or more of the above cations, Group 1 metals, Group 2 metals, and / or other cations or quasi-cation compounds; and X comprises one or more of the above anions.

[0050] In further embodiments, the perovskite material may comprise the empirical formula C'M2X6, wherein C' comprises a cation having a 2+ charge, including one or more of the above cations, diammonium butane, Group 1 metals, Group 2 metals, and / or other cations or cation-like compounds.

[0051] In other embodiments, the perovskite material may comprise an empirical formula C'MX4, wherein C' comprises a cation having a 2+ charge, including one or more of the above cations, diammonium butane, Group 1 metals, Group 2 metals, and / or other cations or cation-like compounds. In such embodiments, the perovskite material may have a 2D structure.

[0052] In one embodiment, the perovskite material may comprise the empirical formula C3M2X9, CM2X7 or C2MX4, wherein: C comprises one or more of the above-mentioned cations, Group 1 metals, Group 2 metals and / or other cations or quasi-cation compounds.

[0053] The perovskite material may also include a mixed ion formulation, wherein C, M or X comprises two or more species. In some embodiments, the perovskite material may include two or more anions or three or more anions. In some embodiments, the perovskite material may include two or more cations or three or more cations. In certain embodiments, the perovskite material may include two or more metals or three or more metals.

[0054] In one example, the perovskite material in the active layer may have a formula CMX 3-y X' y (0 ≥ y ≥ 3), wherein: C comprises one or more cations (e.g., amines, ammonium, Group 1 metals, Group 2 metals, formamidines, guanidinium salts, ethylenetetramine, phosphonium, imidazolium, and / or other cations or quasi-cation compounds); M comprises one or more metals (e.g., Be, Mg, Ca, Sr, Ba, Fe, Cd, Co, Ni, Cu, Ag, Au, Hg, Sn, Ge, Ga, Pb, In, Tl, Sb, Bi, Ti, Zn, Cd, Hg, and Zr); and X and X' comprise one or more anions. In one embodiment, the perovskite material may comprise CPbI 3-y Cl y In another example, the perovskite material in the active layer may have a formula C 1-x C' x MX3 (0 ≥ x ≥ 1), wherein C and C' include one or more cations discussed above. In another example, the perovskite material in the active layer may have a formula CM 1-z M' z X3 (0 ≥ z ≥ 1), wherein M and M' include one or more metals discussed above. In one example, the perovskite material in the active layer may have a formula C 1-x C' x M 1-z M' z X 3-y X' y (0≥x≥1, 0≥y≥3, 0≥z≥1), wherein: C and C' include one or more cations discussed above, M and M' include one or more metals discussed above, and X and X' include one or more anions discussed above.

[0055] By way of explanation, and without implying any limitation, an exemplary embodiment of a perovskite material may be, for example, Cs0.1 FA 0.9 Pb(I 0.9 Cl 0.1 )3, Rb 0.1 FA 0.9 Pb(I 0.9 Cl 0.1 )3Cs 0.1 FA 0.9 PbI3, FAPb 0.5 Sn 0.5 I3, FA 0.83 Cs 0.17 Pb(I 0.6 Br 0.4 )3, FA 0.83 Cs 0.12 R 0.05 Pb(I 0.6 Br 0.4 )3 and FA 0.85 MA 0.15 Pb(I 0.85 Br 0.15 )3.

[0056] Forming the active layer of perovskite material

[0057] In certain embodiments, the perovskite material can be deposited as an active layer on a substrate layer in a PV device by, for example, doctor blade coating, dropcasting, spin casting, slot die printing, screen printing, or inkjet printing using the steps described below.

[0058] First, a lead halide precursor ink is formed. A certain amount of lead halide can be gathered in a controlled atmosphere environment, in a clean dry container (e.g., a controlled atmosphere box with a glove porthole allows the material to be operated in an airless environment). Suitable lead halides include, but are not limited to, lead (II) iodide, lead (II) bromide, lead (II) chloride, and lead (II) fluoride. Lead halide may include a single species of lead halide or it may include a lead halide mixture of an exact ratio. In certain embodiments, the lead halide mixture may include any binary, ternary, or quaternary ratio of 0.001-100 mol% of iodide, bromide, chloride, or fluoride. In one embodiment, the lead halide mixture may include lead chloride (II) and lead iodide (II) at a ratio of about 10:90 mol:mol. In other embodiments, the lead halide mixture may include lead chloride (II) and lead iodide (II) at a ratio of about 5:95, about 7.5:92.5, or about 15:85 mol:mol.

[0059] Alternatively, other lead salt precursors may be used with or in place of the lead halide salts to form the precursor ink. Suitable precursor salts may comprise lead (II) or lead (IV) with any combination of the following anions: nitrate, nitrite, carboxylate, acetate, acetonyl, pyruvate, formate, oxalate, sulfate, sulfite, thiosulfate, phosphate, tetrafluoroborate, hexafluorophosphate, tetrakis(perfluorophenyl)borate, hydrogen, oxide, peroxide, hydroxide, nitrogen, arsenate, arsenite, perchlorate, carbonate, bicarbonate, chromate, dichromate, iodate, bromate, chlorate, chlorite, hypochlorite, hypobromite, cyanate, cyanate, isocyanate, fulminate, thiocyanate, isothiocyanate, azide, tetracarbonylcobaltate, carbamoyldicyanomethyl, dicyanonitrosomethyl, dicyanamide, tricyanomethyl, amide, and permanganate.

[0060] The precursor ink may also contain lead (II) or lead (IV) salts in a molar ratio of 0 to 100% relative to the following metal ions: Be, Mg, Ca, Sr, Ba, Fe, Cd, Co, Ni, Cu, Ag, Au, Hg, Sn, Ge, Ga, Pb, In, Tl, Sb, Bi, Ti, Zn, Cd, Hg and Zr, which are present in the form of salts of the above-mentioned anions.

[0061] Solvent can then be added to the container to dissolve the lead solid to form a lead halide precursor ink. Suitable solvents include, but are not limited to, dry N-cyclohexyl-2-pyrrolidone, alkyl-2-pyrrolidone, dimethylformamide, dialkylformamide, dimethyl sulfoxide (DMSO), methanol, ethanol, propanol, butanol, tetrahydrofuran, formamide, tert-butylpyridine, pyridine, alkylpyridine, pyrrolidine, chlorobenzene, dichlorobenzene, dichloromethane, chloroform, alkyl nitrile, aryl nitrile, acetonitrile, alkoxy alcohol, alkoxyethanol, 2-methoxyethanol, glycol, propylene glycol, ethylene glycol, and combinations thereof. In one embodiment, the lead solid is dissolved in dry dimethylformamide (DMF). In some embodiments, the solvent may also include 2-methoxyethanol and acetonitrile. In some embodiments, 2-methoxyethanol and acetonitrile may be added in a volume ratio of about 25:75 to about 75:25 or at least 25:75. In certain embodiments, the solvent may include 2-methoxyethanol and acetonitrile to DMF in a ratio of about 1:100 to about 1:1 or about 1:100 to about 1:5 by volume. In certain embodiments, the solvent may include 2-methoxyethanol and acetonitrile to DMF in a ratio of at least about 1:100 by volume.

[0062] In certain embodiments, the lead solids may be dissolved at a temperature of about 20°C to about 150°C. In one embodiment, the lead halide solids are dissolved at about 85°C. The lead solids may be dissolved for a period of time required to form a solution, which may occur over a period of time up to about 72 hours. The resulting solution forms the basis of the lead halide precursor ink. In some embodiments, the lead halide precursor ink may have a lead halide concentration of about 0.001M to about 10M, or about 1M.

[0063] Optionally, certain additives may be added to the lead halide precursor ink to affect the final perovskite crystallinity and stability. In some embodiments, the lead halide precursor ink may also include amino acids (e.g., 5-aminopentanoic acid, histidine, glycine, lysine), amino acid hydrohalides (e.g., 5-aminopentanoic acid hydrochloride), IFL surface modification (SAM) agents (such as those previously discussed in the specification), or combinations thereof. Amino acids suitable for lead halide precursor inks may include, but are not limited to, α-amino acids, β-amino acids, γ-amino acids, δ-amino acids, and any combination thereof. In one embodiment, formamidine chloride may be added to the lead halide precursor ink. In other embodiments, any cation halide previously discussed in the specification may be used. In some embodiments, a combination of additives, including, for example, a combination of formamidine chloride and 5-aminopentanoic acid hydrochloride, may be added to the lead halide precursor ink.

[0064] In some embodiments, additives including formamidine chloride and / or 5-aminovaleric acid hydrochloride may be added to the lead halide precursor ink at various concentrations, depending on the desired properties of the resulting perovskite material. In one embodiment, the additive may be added at a concentration of about 1 nM to about 1 M, about 1 μM to about 1 M, or about 1 μM to about 1 mM.

[0065] Optionally, in certain embodiments, water may be added to the lead halide precursor ink. As an explanation, and without limiting the invention to any particular theory or mechanism, the presence of water affects the perovskite thin film crystal growth. Under normal circumstances, water can be absorbed from the air as vapor. However, the perovskite PV crystallinity can be controlled by adding water directly to the lead halide precursor ink at a specific concentration. Suitable water includes distilled deionized water or any other water source that is substantially free of contaminants (including minerals). It has been found that the conversion efficiency of perovskite PV light to electricity can be nearly three times that of a completely dry device with the addition of water, based on optical IV scans.

[0066] Water can be added to the lead halide precursor ink at various concentrations depending on the desired properties of the resulting perovskite material. In one embodiment, water can be added at a concentration of about 1 nL / mL to about 1 mL / mL, about 1 μL / mL to about 0.1 mL / mL, or about 1 μL / mL to about 20 μL / mL.

[0067] Then, the lead halide precursor ink can be deposited on the desired substrate. Suitable substrate layers may include any substrate layer previously confirmed in the present invention. As noted above, lead halide precursor ink can be deposited by various means including but not limited to: droplet casting, spin coating (spin casting), slit extrusion printing, inkjet printing, gravure printing, screen printing, sputtering, PE-CVD, atomic layer deposition, thermal evaporation, spraying, and any combination thereof. In certain embodiments, the lead halide precursor ink can be spin-coated on the substrate at a speed of about 500rpm to about 10,000rpm for a period of about 5 seconds to about 600 seconds. In one embodiment, the lead halide precursor ink can be spin-coated on the substrate at about 3000rpm for about 30 seconds. The lead halide precursor ink can be deposited on the substrate in an ambient atmosphere at a humidity range of about 0% relative humidity to about 50% relative humidity. Then, the lead halide precursor ink is dried to form a film in a substantially anhydrous atmosphere (i.e., less than 30% relative humidity).

[0068] The film may then be thermally annealed at a temperature of about 20°C to about 300°C for a period of up to about 24 hours. In one embodiment, the film may be thermally annealed at a temperature of about 50°C for about ten minutes. The active layer of perovskite material may then be completed by a conversion process in which the precursor film is immersed or rinsed with a solution comprising a solvent or a mixture of solvents (e.g., DMF, isopropanol, methanol, ethanol, butanol, chloroform, chlorobenzene, dimethyl sulfoxide, water) and a salt (e.g., methylammonium iodide, formamidine iodide, guanidine iodide, 1,2,2-triaminovinylammonium iodide, 5-aminopentanoic acid hydroiodide) at a concentration of 0.001M to 10M. In certain embodiments, the film may also be post-annealed thermally in the same manner as in the first line of this paragraph.

[0069] In some embodiments, the lead salt precursor may be deposited on a substrate to form a lead salt film. The substrate may have a temperature approximately equal to ambient temperature or have a controlled temperature of 0°C to 500°C. The lead salt precursor may be deposited by any of the various methods discussed above for lead halide precursor inks. In certain embodiments, the deposition of the lead salt precursor may include sheet-to-sheet or roll-to-roll manufacturing methodologies. The deposition of the lead salt precursor may be performed in various atmospheres, at ambient pressure, or at a pressure below atmospheric pressure or ambient (e.g., 1 mTorr to 500 mTorr). The deposition atmosphere may include ambient air, a controlled humidity environment (e.g., 0-100 g H2O / m 3Gas), pure argon, pure nitrogen, pure oxygen, pure hydrogen, pure helium, pure neon, pure krypton, pure CO2, or any combination of the foregoing gases. The controlled humidity environment may include an environment in which the absolute humidity or relative humidity % is maintained at a fixed value or in which the absolute humidity or relative humidity % varies according to a predetermined set point or a predetermined function. In specific embodiments, deposition may occur in a controlled humidity environment having a relative humidity % greater than or equal to 0% and less than or equal to 50%. In other embodiments, deposition may occur in a controlled humidity environment containing more than or equal to 0 g H2O / m 3 Gas and less than or equal to 20g H2O / m 3 Unless otherwise described, any annealing or deposition step described herein may be performed under the aforementioned conditions.

[0070] The lead salt precursor may be a liquid, a gas, a solid, or a combination of these states of matter, such as a solution, a suspension, a colloid, a foam, a gel, or an aerosol. In some embodiments, the lead salt precursor may be a solution containing one or more solvents. For example, the lead salt precursor may contain one or more of the following: N-cyclohexyl-2-pyrrolidone, alkyl-2-pyrrolidone, dimethylformamide, dialkylformamide, dimethyl sulfoxide (DMSO), acetonitrile, methanol, ethanol, propanol, butanol, tetrahydrofuran, formamide, tert-butylpyridine, pyridine, alkylpyridine, pyrrolidine, chlorobenzene, dichlorobenzene, dichloromethane, chloroform, and combinations thereof. The lead salt precursor may include a single lead salt (e.g., lead iodide (II), lead thiocyanate (II)) or any combination of those disclosed herein (e.g., PbI2+PbCl2; PbI2+Pb(SCN)2). The lead salt precursor may also contain one or more additives, such as amino acids (e.g., 5-aminopentanoic acid hydroiodide), 1,8-diiodooctane, 1,8-dithiooctane, halogenated formamidine, acetic acid, trifluoroacetic acid, methylammonium halide, or water. The lead salt precursor is dried in a substantially anhydrous atmosphere (i.e., less than 30% relative humidity) to form a film. Then, the lead salt film may be thermally annealed for the same time as discussed above for the lead halide precursor ink film. The annealing environment may have the same pressure and atmosphere as the lead salt deposition environment and conditions discussed above. In a specific embodiment, annealing may occur in a controlled humidity environment having a relative humidity of greater than or equal to 0% and less than or equal to 50%. In other embodiments, annealing may occur in a controlled humidity environment containing more than or equal to 0 g H2O / m 3 Gas and less than or equal to 20g H2O / m 3 The gas is kept in a controlled humidity environment.

[0071] After the lead salt precursor is deposited, a second salt precursor (e.g., formamidine iodide, formamidine thiocyanate, guanidine thiocyanate) may be deposited on the lead salt film, wherein the lead salt film may have a temperature approximately equal to ambient temperature or have a controlled temperature of 0° C. to 500° C. In some embodiments, the second salt precursor may be deposited at ambient temperature or at an elevated temperature of about 25° C. to 125° C. The second salt precursor may be deposited by any of the methods discussed above with respect to the lead halide precursor ink. The deposition of the second salt precursor may be carried out in the same environment and under the same conditions as discussed above with respect to the first salt precursor.

[0072] In some embodiments, the second salt precursor can be a solution containing one or more solvents, such as one or more of the solvents discussed above with respect to the first lead salt precursor.

[0073] After the deposition of the lead salt precursor and the second salt precursor, the substrate may be annealed. Annealing the substrate may convert the lead salt precursor and the second salt precursor into a perovskite material (e.g., FAPbI3, GAPb(SCN)3, FASnI3). Annealing may occur in the same environment and under the same conditions as the lead salt deposition environment and conditions discussed above. In specific embodiments, annealing may occur in a controlled humidity environment having a relative humidity of greater than or equal to 0% and less than or equal to 50%. In other embodiments, annealing may occur in a controlled humidity environment containing more than or equal to 0 g H2O / m 3 Gas and less than or equal to 20g H2O / m 3 The annealing may occur in a controlled humidity environment of gases. In some embodiments, the annealing may occur at a temperature greater than or equal to 50°C and less than or equal to 300°C.

[0074] For example, in a specific embodiment, a FAPbI3 perovskite material can be formed by the following method. First, a lead (II) halide precursor comprising PbI2 and PbCl2 in a molar ratio of about 90:10 dissolved in anhydrous DMF can be deposited on a substrate by spin coating or slit extrusion printing. The lead halide precursor ink can be dried for about one hour (+15 minutes) in a substantially anhydrous atmosphere (i.e., less than 30% relative humidity) to form a film. The film can then be thermally annealed for about ten minutes at a temperature of about 50°C (+10°C). Next, a formamidine iodide precursor comprising 25-60mg / mL of formamidine iodide dissolved in anhydrous isopropanol can be deposited on a lead halide film by spin coating or slit extrusion printing. After depositing the lead halide precursor and the formamidine iodide precursor, a film can be formed at about 25% relative humidity (about 4 to 7g H2O / m 3 The substrate is annealed at about 125° C. to 200° C. to form a lead formamidinium iodide (FAPbI 3 ) perovskite material.

[0075] In further embodiments, the perovskite material may comprise C'CPbX3, wherein C' is one or more Group 1 metals (e.g., Li, Na, K, Rb, Cs). In specific embodiments, M' may be cesium (Cs). In yet other embodiments, the perovskite material may comprise C'vCwPbyXz, wherein C' is one or more Group 1 metals and v, w, y, and z represent real numbers from 1 to 20. In certain embodiments, the perovskite material may be deposited as an active layer on a substrate layer in a PV device by, for example, drop casting, spin casting, gravure coating, blade coating, reverse gravure coating, slot die printing, screen printing, or inkjet printing.

[0076] First, a lead halide solution is formed. The lead halide solution can be prepared in any of the same methods as the lead halide precursor ink discussed above and using similar compositions.

[0077] Other lead salt precursors, such as those discussed above with respect to the lead halide precursor inks, may be used along with or in place of the lead halide salt to form the lead salt solution.

[0078] Next, a Group 1 metal halide solution is formed. A certain amount of Group 1 metal halide can be gathered in a clean dry container in a controlled atmosphere environment. Suitable Group 1 metal halides include, but are not limited to, cesium iodide, cesium bromide, cesium chloride, cesium fluoride, rubidium iodide, rubidium bromide, rubidium chloride, rubidium fluoride, lithium iodide, lithium bromide, lithium chloride, lithium fluoride, sodium iodide, sodium bromide, sodium chloride, sodium fluoride, potassium iodide, potassium bromide, potassium chloride, potassium fluoride. The Group 1 metal halide can include a single species of Group 1 metal halide or it can include a mixture of Group 1 metal halides in a precise ratio.

[0079] Alternatively, other Group 1 metal salt precursors may be used together with or in place of the Group 1 metal halide salt to form the Group 1 metal salt solution. Suitable precursor Group 1 metal salts can comprise a Group 1 metal and any combination of the following anions: nitrate, nitrite, carboxylate, acetate, formate, oxalate, sulfate, sulfite, thiosulfate, phosphate, tetrafluoroborate, hexafluorophosphate, tetrakis(perfluorophenyl)borate, hydrogen, oxide, peroxide, hydroxide, nitrogen, arsenate, arsenite, perchlorate, carbonate, bicarbonate, chromate, dichromate, iodate, bromate, chlorate, chlorite, hypochlorite, hypobromite, cyanate, cyanate, isocyanate, fulminate, thiocyanate, isothiocyanate, azide, tetracarbonylcobaltate, carbamoyldicyanomethyl, dicyanonitrosomethyl, dicyanamide, tricyanomethyl, amide, and permanganate.

[0080] Then, a solvent may be added to the container to dissolve the Group 1 metal halide solid to form a Group 1 metal halide solution. Suitable solvents include, but are not limited to, dry N-cyclohexyl-2-pyrrolidone, alkyl-2-pyrrolidone, dimethylformamide (DMF), dialkylformamide, dimethyl sulfoxide (DMSO), acetonitrile, methanol, ethanol, propanol, butanol, tetrahydrofuran, formamide, tert-butylpyridine, pyridine, alkylpyridine, pyrrolidine, chlorobenzene, dichlorobenzene, dichloromethane, chloroform, and combinations thereof. In one embodiment, the lead solid is dissolved in dry dimethyl sulfoxide (DMSO). The Group 1 metal halide solid may be dissolved at a temperature of about 20°C to about 150°C. In one embodiment, the Group 1 metal halide solid is dissolved at room temperature (i.e., about 25°C). The Group 1 metal halide solid may be dissolved for the time required to form a solution, which may occur over a period of up to about 72 hours. The resulting solution forms a Group 1 metal halide solution. In some embodiments, the Group 1 metal halide solution can have a Group 1 metal halide concentration of about 0.001 M to about 10 M, or about 1 M. In some embodiments, the Group 1 metal halide solution can also include an amino acid (e.g., 5-aminovaleric acid, histidine, glycine, lysine), an amino acid hydrohalide (e.g., 5-aminovaleric acid hydrochloride), an IFL surface modification (SAM) agent (such as those discussed previously in the specification), or a combination thereof.

[0081] Next, the lead halide solution is mixed with the Group 1 metal halide solution to form a thin film precursor ink. The lead halide solution and the Group 1 metal halide solution may be mixed in a ratio such that the resulting thin film precursor ink has a molar concentration of the Group 1 metal halide of 0% to 25% of the molar concentration of the lead halide. In specific embodiments, the thin film precursor ink may have a molar concentration of the Group 1 metal halide of 1%, 5%, 10%, 15%, 20%, or 25% of the molar concentration of the lead halide. In some embodiments, the lead halide solution and the Group 1 metal halide solution may be stirred or agitated during or after mixing.

[0082] The thin film precursor ink can then be deposited on the desired substrate by any deposition method discussed above. Suitable substrate layers may include any substrate layer identified in the foregoing text of the present invention. In certain embodiments, the thin film precursor ink can be spin-coated on the substrate at a speed of about 500 rpm to about 10,000 rpm for a period of about 5 seconds to about 600 seconds. In one embodiment, the thin film precursor ink can be spin-coated on the substrate at about 3000 rpm for about 30 seconds. The thin film precursor ink can be deposited on the substrate in an ambient atmosphere at a humidity range of about 0% relative humidity to about 50% relative humidity. Then, in a substantially anhydrous atmosphere (i.e., less than 30% relative humidity or 7g H2O / m 3 ) Dry the thin film precursor ink to form a thin film.

[0083] The film may then be thermally annealed at a temperature of about 20°C to about 300°C for a period of up to about 24 hours. In one embodiment, the film may be thermally annealed at a temperature of about 50°C for about ten minutes. The perovskite material active layer may then be completed by a conversion process in which the precursor film is immersed or rinsed with a salt solution comprising a solvent or a mixture of solvents (e.g., DMF, isopropanol, methanol, ethanol, butanol, chloroform, chlorobenzene, dimethyl sulfoxide, water) and a salt at a concentration of 0.001M to 10M (e.g., methylammonium iodide, formamidine iodide, guanidine iodide, 1,2,2-triaminovinylammonium iodide, 5-aminopentanoic acid hydroiodide). In certain embodiments, the perovskite material film may also be post-annealed in the same manner as in the first line of this paragraph.

[0084] In some embodiments, a salt solution can be prepared by aggregating salts in a clean dry container in a controlled atmosphere environment. Suitable salts include, but are not limited to, methylammonium iodide, formamidine iodide, guanidine iodide, imidazole iodide, ethylenetetramine iodide, 1,2,2-triaminovinyl ammonium iodide, and 5-aminopentanoic acid hydroiodide. Other suitable salts may include any organic cation described above in the chapter name "perovskite material". The salt may contain a single species salt or it may contain a salt mixture of an exact ratio. Next, a solvent may be subsequently added to the container to dissolve the salt solid to form a salt solution. Suitable solvents include those listed in the previous paragraph and their combinations. In one embodiment, the formamidine iodide salt solid is dissolved in isopropanol. The salt solid may be dissolved at a temperature of about 20°C to about 150°C. In one embodiment, the salt solid is dissolved at room temperature (i.e., about 25°C). The salt solid may dissolve for the time required to continuously form a solution, which may occur within a time period of up to about 72 hours. The resulting solution forms a salt solution. In some embodiments, the saline solution can have a salt concentration of about 0.001 M to about 10 M. In one embodiment, the saline solution has a salt concentration of about 1M.

[0085] For example, using the method described above, using lead (II) iodide solution, cesium iodide solution and methylammonium iodide (MA) salt solution, a compound having the formula Cs i MA 1-i PbI3 perovskite material, wherein i is equal to a value between 0 and 1. As another example, using a lead (II) iodide solution, a rubidium iodide solution, and a formamidine iodide (FA) salt solution, a perovskite material having the formula Rb i FA 1-i PbI3 perovskite material, wherein i is equal to a value between 0 and 1. As another example, using lead (II) iodide solution, cesium iodide solution and formamidine iodide (FA) salt solution, a perovskite material having the formula Cs i FA 1-iPbI3 perovskite material, wherein i is equal to a value between 0 and 1. As another example, using lead (II) iodide solution, potassium iodide solution and formamidine iodide (FA) salt solution, a perovskite material having the formula K i FA 1-i PbI3 perovskite material, wherein i is equal to a value between 0 and 1. As another example, using a lead (II) iodide solution, a sodium iodide solution, and a formamidine iodide (FA) salt solution, a perovskite material having the formula Na i FA 1-i PbI3 perovskite material, wherein i is equal to a value between 0 and 1. As another example, using a lead (II) iodide-lead (II) chloride mixture solution, a cesium iodide solution, and a formamidine iodide (FA) salt solution, a perovskite material having the formula Cs i FA 1-i PbI 3-y Cl y A perovskite material, wherein i is equal to a value between 0 and 1 and y represents a value between 0 and 3.

[0086] In a specific embodiment, the lead halide solution described above may have a ratio of PbI2 to PbCl2 of 90:10 based on a molar ratio. A cesium iodide (CsI) solution may be added to the lead halide solution by the method described above to form a thin film precursor ink having 10 mol% CsI. This thin film precursor solution may be used to produce a FAPbI3 perovskite material according to the method described above. The addition of cesium ions through the CsI solution described above may cause chloride anions and cesium atoms to be incorporated into the FAPbI3 lattice. This may result in a greater degree of lattice contraction than the addition of cesium ions or rubidium ions without the addition of chloride ions described above. Table 1 below shows the lattice parameters of FAPbI3 perovskite materials with 10 mol% rubidium and 20 mol% chlorine (e.g., 10 mol% PbCl2), 10 mol% cesium, and 10 mol% cesium and 20 mol% chlorine, where the mol% concentration represents the concentration of the additive relative to the lead atoms in the lead halide solution. As can be seen in Table 1, the FAPbI3 perovskite material with added cesium and chlorine has a smaller lattice parameter than the other two perovskite material samples.

[0087] Table 1

[0088]

[0089] In addition, the data show that FAPbI3 perovskite materials with additions of rubidium, cesium and / or chlorine have a Pm3-m cubic structure. It has been observed that FAPbI3 perovskites with up to and including 10 mol% Rb and 10 mol% Cl, or 10 mol% Cs, or 10 mol% Cs and 10 mol% Cl maintain a Pm3-m cubic crystal structure. Figure 2X-ray diffraction patterns are shown corresponding to each of the samples presented in Table 1. Tables 2-4 provide X-ray diffraction peaks and intensities for the three perovskite materials shown in Table 1. Data were collected at ambient conditions on a Rigaku Miniflex 600 using a Cu Ka radiation source at a scan speed of 1.5 degrees 2θ / min.

[0090] Table 2

[0091]

[0092] Table 3

[0093]

[0094] Table 4

[0095]

[0096] exist The geometrically expected X-ray diffraction patterns of cubic Pm3-m materials are shown in Table 5. As can be seen from the data, the perovskite materials produced using 10 mol% Rb and 10 mol% Cl, 10 mol% Cs, and 10% Cs and 10% Cl each have a diffraction pattern that fits the expected pattern for a cubic Pm3-m perovskite material.

[0097] Table 5

[0098]

[0099] Method for forming a perovskite material layer using an ionic liquid

[0100] In certain embodiments, an ionic liquid may be introduced into any of the methods of forming a perovskite material discussed herein. In some embodiments, the ionic liquid may include a molten salt having a low melting point. In certain embodiments, the ionic liquid may include a salt having a melting point of 100°C or less, 80°C or less, or 60°C or less. Among the many potential advantages of the methods, compositions, and devices of the present invention, only some of which are hinted at herein, the use of ionic liquids in forming perovskite materials can enhance the perovskite crystallization process and provide oxygen and water (i.e., hydrophobicity) to the perovskite material, which can produce more robust, durable, and efficient perovskite devices.

[0101] In some embodiments, the ionic liquid may include a salt of the general formula AB, wherein A is one or more cations and B is one or more anions. In certain embodiments, A may include ammonium, the general formula [NR4] +The organic cation, wherein the R groups can be the same or different groups. Suitable R groups include, but are not limited to: hydrogen, methyl, ethyl, propyl, butyl, pentyl or their isomers; any cyclic, branched or linear alkane, alkene or alkyne C x H y , wherein x = 1-20, y = 1-42; alkyl halide C x H y X z , x=1-20, y=0-42, z=1-42, X=F, Cl, Br or I; any aromatic group (e.g. phenyl, alkylphenyl, alkoxyphenyl, pyridine, naphthylene); a cyclic complex containing at least one nitrogen in the ring (e.g. pyridine, pyrrole, pyrrolidine, piperidine, tetrahydroquinoline, 2-hexahydropyrimidin-2-ylidenehexahydropyrimidine, octahydropyrazino[2,3-b]pyrazine, pyrazino[2,3-b]pyrazine, quinoxalino[2,3-b]quinoxaline); any sulfur-containing group (e.g. sulfoxide, mercapto, alkyl sulfide); any nitrogen-containing group (nitrogen any alkoxy or -OCxHy group, wherein x=0-20 and y=1-42; and any halogen or pseudohalogen: F, Cl, Br, I, SCN or CN.

[0102] In certain embodiments, A of the ionic liquid may include formamidine, with the general formula [R2NCRNR2] + The organic cation wherein the R groups may be the same or different groups. Suitable R groups include but are not limited to any R groups in the preceding paragraphs.

[0103]

[0104] Formula 1 shows a compound having the general formula [R2NCRNR2] as described above. + Formula 2 shows exemplary structures of several formamidinium cations that can serve as cation "A" in ionic liquids.

[0105]

[0106] In certain embodiments, A may include a guanidine salt, of the general formula [(R2N)2C=NR2] + The organic cation wherein the R groups may be the same or different groups. Suitable R groups include but are not limited to any R groups in the preceding paragraphs.

[0107]

[0108] Formula 3 shows a compound having the general formula [(R2N)2C=NR2] as described above. + Formula 4 shows examples of the structures of several guanidinium cations that can serve as cation "A" in an ionic liquid.

[0109]

[0110]

[0111] In certain embodiments, A may include an ethylenetetramine cation of the general formula [(R2N)2C=C(NR2)2] + An organic cation, wherein the R groups may be the same or different groups.

[0112] Suitable R groups include, but are not limited to, any of the R groups in the preceding paragraphs.

[0113]

[0114] Formula 5 shows a compound having the general formula [(R2N)2C=C(NR2)2] + Formula 6 shows examples of the structures of several ethylenetetramine ions that can serve as cation "A" in an ionic liquid.

[0115]

[0116] In certain embodiments, A may include an imidazolium cation of the general formula [CRNRCRNRCR] + An aromatic cyclic organic cation wherein the R groups may be the same or different groups. Suitable R groups may include, but are not limited to, any of the R groups in the preceding paragraphs.

[0117]

[0118] Formula 7 shows a compound having the general formula [CRNRCRNRCR] as described above. + Formulas 8 and 9 show exemplary structures that can serve as cation "A" in ionic liquids.

[0119]

[0120] In certain embodiments, A may include the general formula [R3R2R1PNPR4R5R6] + A cation, wherein R1-R6 may be the same or different groups. Suitable R groups may include, but are not limited to, any of the R groups in the preceding paragraphs. In some embodiments, one or more R groups may include Among them R7-R 11 Any suitable R group discussed in the previous paragraph may be used.

[0121]

[0122] Formula 10 shows a general formula [R3R2R1PNPR4R5R6] as described above that may be suitable for ionic liquids. + The structure of the cation.

[0123]

[0124] Formula 11 shows a general structure of a cation that may be suitable for an ionic liquid. Suitable R groups for R1-R6 of this structure may include, but are not limited to, any of the R groups in the previous paragraphs.

[0125] Formula 12 shows an exemplary structure that can serve as the cation "A" in the ionic liquid.

[0126]

[0127] Fig.12 Illustrations of additional structures of organic molecules that can function as the cation "A" of an ionic liquid according to certain embodiments are provided.

[0128] In some embodiments, the anion B of the ionic liquid may include one or more halide ions (e.g., chloride ions). In certain embodiments, B may alternatively or additionally include a Group 16 anion. In certain embodiments, the Group 16 anion may be an oxygen ion, a sulfur ion, a selenium ion, or a tellurium ion. In certain embodiments, B may include, but is not limited to, F, Cl, Br, I, SCN, CN, or any other pseudohalogen. Other acceptable non-halogen anions may include, but are not limited to, nitrate, nitrite, carboxylate, acetate, acetonyl, pyruvate, formate, oxalate, sulfate, sulfite, thiosulfate, phosphate, tetrafluoroborate, hexafluorophosphate, tetrakis(perfluorophenyl)borate, hydrogen, oxide, peroxide, hydroxide, nitrogen, arsenate, arsenite, perchlorate, carbonate, bicarbonate, chromate, dichromate, iodate, bromate, chlorate, chlorite, hypochlorite, hypobromite, cyanate, cyanate, isocyanate, fulminate, thiocyanate, isothiocyanate, azide, tetracarbonylcobaltate, carbamoyldicyanomethyl, dicyanonitrosomethyl, dicyanamide, tricyanomethyl, amide, and permanganate. In certain embodiments, B may include one or more of bis(trifluoromethane)sulfonimide (TFSI) and tetraphenylborate.

[0129] In certain embodiments, B may include the general formula [BR1R2R3R4] -borate anion, wherein R1-R4 may be the same or different groups. Suitable R groups may include, but are not limited to: halogen or pseudohalogen (e.g., F, Cl, Br, I, SCN, and CN); alkyl halides CxHyXz, x=1-20, y=0-42, z=1-42, X=F, Cl, Br, or I; any aromatic group (e.g., phenyl, alkylphenyl, alkoxyphenyl, pyridine, naphthylene); and halogen-substituted aromatic groups (e.g., pentafluorophenyl). In some embodiments, one or more R groups may include F,

[0130]

[0131] Formula 13 shows the above-mentioned ionic liquid having the general formula [BR1R2R3R4] - The structure of the anion.

[0132]

[0133] Fig.13 Illustrations of additional structures of organic molecules that can function as anions "B" of ionic liquids according to certain embodiments are provided.

[0134] Ionic liquids may be employed in any of the steps of forming perovskite materials and layers discussed in the present invention. With the benefit of the present invention, one skilled in the art will appreciate the steps in which ionic liquids may be incorporated and are beneficial to the formation of perovskite materials. For example, in certain embodiments, one or more ionic liquids may be added directly to a perovskite precursor ink, to one or more solvents used in the perovskite formation process, to one or more salt precursors, and / or to one or more Group 1 metal halide solutions. In certain embodiments, one or more ionic liquids may be contained in a solution comprising one or more Group 1 metals and lead halide. In some embodiments, an ionic liquid may be added to a perovskite precursor solution prior to deposition and annealing.

[0135] Depending on the desired properties of the resulting perovskite material, the ionic liquid can be added to the solution (e.g., lead halide precursor ink) at various concentrations. In one embodiment, the ionic liquid can be added at a concentration of about 0.05 mol% to about 10 mol%, where the mol% concentration represents the concentration of the additive relative to the lead atoms in the lead halide solution. In certain embodiments, the ionic liquid can be added at a concentration of about 0.01 to about 5 mol%, or about 0.05 to about 1 mol%. In some embodiments, the ionic liquid can be added at a concentration of less than 10 mol%, less than 5 mol%, or less than 1 mol%.

[0136] In some embodiments, the perovskite material formed using an ionic liquid may include a mixed ion formulation, where C, M, or X includes two or more species. For example, the perovskite material may include CMX 3-x X' x (0 ≥ x ≥ 3), wherein: C comprises one or more cations (e.g., amines, ammonium, methylammonium, Group 1 metals, Group 2 metals, formamidines, guanidiniums, ethylenetetramines, phosphines, imidazoliums, and / or other cations or quasi-cation compounds); M comprises one or more metals (e.g., Be, Mg, Ca, Sr, Ba, Fe, Cd, Co, Ni, Cu, Ag, Au, Hg, Sn, Ge, Ga, Pb, In, Tl, Sb, Bi, Ti, Zn, Cd, Hg, and Zr); and X and X' comprise one or more anions. In specific embodiments, C may be Rb, Cs, formamidine, and methylammonium. In some embodiments, the perovskite material may comprise CPbI 3-y Cl y In certain embodiments, the perovskite material can be deposited as an active layer on a substrate layer in a PV device by, for example, drop casting, spin casting, gravure coating, doctor blade coating, reverse gravure coating, slot die printing, screen printing, or inkjet printing using the steps described below.

[0137] The example of forming a perovskite material including an ionic liquid is described below. First, a lead halide solution is formed. A certain amount of lead halide can be gathered in a clean dry container in a controlled atmosphere environment. Suitable lead halides include but are not limited to lead (II) iodide, lead (II) bromide, lead chloride (II) and lead fluoride (II). Lead halide may include a single species lead halide or it may include a lead halide mixture of an exact ratio. In one embodiment, lead halide may include lead (II) iodide. In certain embodiments, the lead halide mixture may include any binary, ternary or quaternary ratio of 0.001-100mol% of iodide, bromide, chloride or fluoride. In one embodiment, the lead halide mixture may include lead chloride (II) and lead iodide (II) in a ratio of about 10:90mol:mol. In other embodiments, the lead halide mixture may include lead chloride (II) and lead iodide (II) in a ratio of about 5:95, about 7.5:92.5 or about 15:85mol:mol. Alternatively, other lead salt precursors may be used together with or in place of the lead halide salt to form the lead salt solution. Suitable precursor lead salts may comprise lead (II) or lead (IV) with any combination of the following anions: nitrate, nitrite, carboxylate, acetate, formate, oxalate, sulfate, sulfite, thiosulfate, phosphate, tetrafluoroborate, hexafluorophosphate, tetrakis(perfluorophenyl)borate, hydrogen, oxide, peroxide, hydroxide, nitrogen, arsenate, arsenite, perchlorate, carbonate, bicarbonate, chromate, dichromate, iodate, bromate, chlorate, chlorite, hypochlorite, hypobromite, cyanate, cyanate, isocyanate, fulminate, thiocyanate, isothiocyanate, azide, tetracarbonylcobaltate, carbamoyldicyanomethyl, dicyanonitrosomethyl, dicyanamide, tricyanomethyl, amide, and permanganate. The lead salt solution may also contain lead (II) or lead (IV) salts in a molar ratio of 0 to 100% relative to the following metal ions: Be, Mg, Ca, Sr, Ba, Fe, Cd, Co, Ni, Cu, Ag, Au, Hg, Sn, Ge, Ga, Pb, In, Tl, Sb, Bi, Ti, Zn, Cd, Hg and Zr, which are present in the form of salts of the above-mentioned anions.

[0138] In certain embodiments, one or more ionic liquids may be added to the lead halide, followed by any other additives (e.g., solvents). Then, a solvent may be added to a container to dissolve the lead halide solid to form a lead halide solution. In other embodiments, one or more ionic liquids may be added to the lead halide solution after the solvent is added, added to the lead halide solution simultaneously with the solvent, or mixed with the solvent before the lead halide is introduced. Suitable solvents include, but are not limited to, dry N-cyclohexyl-2-pyrrolidone, alkyl-2-pyrrolidone, dimethylformamide (DMF), dialkylformamide, dimethyl sulfoxide (DMSO), acetonitrile, methanol, ethanol, propanol, butanol, tetrahydrofuran, formamide, tert-butylpyridine, pyridine, alkylpyridine, pyrrolidine, chlorobenzene, dichlorobenzene, dichloromethane, chloroform, and combinations thereof. In one embodiment, the lead solid is dissolved in dry dimethylformamide (DMF). The lead halide solid may be dissolved at a temperature of about 20°C to about 150°C. In one embodiment, the lead halide solid is dissolved at about 85°C. The lead halide solid can be dissolved for the time required to continue to form a solution, which can occur within a period of up to about 72 hours. The resulting solution forms the basis of the lead halide precursor ink. In some embodiments, the lead halide precursor ink may have a lead halide concentration of about 0.001M to about 10M. In one embodiment, the lead halide precursor ink has a lead halide concentration of about 1M. In some embodiments, the lead halide solution may also include an amino acid (e.g., 5-aminopentanoic acid, histidine, glycine, lysine), an amino acid hydrohalide (e.g., 5-aminopentanoic acid hydrochloride), an IFL surface modification (SAM) agent (such as those previously discussed in the specification), or a combination thereof.

[0139] Next, a Group 1 metal halide solution is formed. A certain amount of Group 1 metal halide can be gathered in a clean dry container in a controlled atmosphere environment. Suitable Group 1 metal halides include, but are not limited to: cesium iodide, cesium bromide, cesium chloride, cesium fluoride, rubidium iodide, rubidium bromide, rubidium chloride, rubidium fluoride, lithium iodide, lithium bromide, lithium chloride, lithium fluoride, sodium iodide, sodium bromide, sodium chloride, sodium fluoride, potassium iodide, potassium bromide, potassium chloride, potassium fluoride. The Group 1 metal halide may contain a single species of Group 1 metal halide or it may contain a precise ratio of a mixture of Group 1 metal halides. In one embodiment, the Group 1 metal halide may contain cesium iodide. In another embodiment, the Group 1 metal halide may contain rubidium iodide. In another embodiment, the Group 1 metal halide may contain sodium iodide. In another embodiment, the Group 1 metal halide may contain potassium iodide. In some embodiments, the Group 1 metal halide can be gathered with the lead halide in a clean, dry container before adding other additives (e.g., ionic liquids or solvents). In some embodiments, the Group 1 metal halide and lead halide can be weighed and added in a specific order. In certain embodiments, the lead halide can be weighed and added to the container before adding any Group 1 metal halide.

[0140] Alternatively, other Group 1 metal salt precursors may be used with or in place of the Group 1 metal halide salt to form the Group 1 metal salt solution. Suitable precursor Group 1 metal salts can comprise a Group 1 metal and any combination of the following anions: nitrate, nitrite, carboxylate, acetate, formate, oxalate, sulfate, sulfite, thiosulfate, phosphate, tetrafluoroborate, hexafluorophosphate, tetrakis(perfluorophenyl)borate, hydrogen, oxide, peroxide, hydroxide, nitrogen, arsenate, arsenite, perchlorate, carbonate, bicarbonate, chromate, dichromate, iodate, bromate, chlorate, chlorite, hypochlorite, hypobromite, cyanate, cyanate, isocyanate, fulminate, thiocyanate, isothiocyanate, azide, tetracarbonylcobaltate, carbamoyldicyanomethyl, dicyanonitrosomethyl, dicyanamide, tricyanomethyl, amide, and permanganate.

[0141] Then, a solvent may be added to the container to dissolve the Group 1 metal halide solid to form a Group 1 metal halide solution. In certain embodiments, one or more ionic liquids are added to the Group 1 metal halide solid or the Group 1 metal halide solution after the solvent is added. In other embodiments, one or more ionic liquids may be added simultaneously with the solvent, or the solvent may be added first and then introduced into the lead halide solution. Suitable solvents include, but are not limited to, dry N-cyclohexyl-2-pyrrolidone, alkyl-2-pyrrolidone, dimethylformamide (DMF), dialkylformamide, dimethyl sulfoxide (DMSO), acetonitrile, methanol, ethanol, propanol, butanol, tetrahydrofuran, formamide, tert-butylpyridine, pyridine, alkylpyridine, pyrrolidine, chlorobenzene, dichlorobenzene, dichloromethane, chloroform, and combinations thereof. In one embodiment, the lead solid is dissolved in dry dimethyl sulfoxide (DMSO). The Group 1 metal halide solid may be dissolved at a temperature of about 20°C to about 150°C. In one embodiment, the Group 1 metal halide solid dissolves at room temperature (i.e., about 25° C.). The Group 1 metal halide solid may dissolve for the time required to form a solution, which may occur over a period of up to about 72 hours. The resulting solution forms a Group 1 metal halide solution. In some embodiments, the Group 1 metal halide solution may have a Group 1 metal halide concentration of about 0.001M to about 10M. In one embodiment, the Group 1 metal halide solution has a Group 1 metal halide concentration of about 1M. In some embodiments, the Group 1 metal halide solution may also include an amino acid (e.g., 5-aminopentanoic acid, histidine, glycine, lysine), an amino acid hydrohalide (e.g., 5-aminopentanoic acid hydrochloride), an IFL surface modification (SAM) agent (such as those previously discussed in the specification), or a combination thereof.

[0142] Next, the lead halide solution and the Group 1 metal halide solution are mixed to form a lead halide precursor ink. In certain embodiments, one or more ionic liquids may be added to the lead halide precursor ink. The lead halide solution and the Group 1 metal halide solution may be mixed in a ratio such that the resulting thin film precursor ink has a molar concentration of Group 1 metal halide of 0% to 25% of the molar concentration of the lead halide. In a specific embodiment, the lead halide precursor ink may have a molar concentration of Group 1 metal halide of 1% of the molar concentration of the lead halide. In a specific embodiment, the lead halide precursor ink may have a molar concentration of Group 1 metal halide of 5% of the molar concentration of the lead halide. In a specific embodiment, the lead halide precursor ink may have a molar concentration of Group 1 metal halide of 10% of the molar concentration of the lead halide. In a specific embodiment, the lead halide precursor ink may have a molar concentration of Group 1 metal halide of 15% of the molar concentration of the lead halide. In a specific embodiment, the thin film precursor ink may have a molar concentration of Group 1 metal halide of 20% of the molar concentration of lead halide. In a specific embodiment, the lead halide precursor ink may have a molar concentration of Group 1 metal halide of 25% of the molar concentration of lead halide. In some embodiments, the lead halide solution, the Group 1 metal halide solution, and / or the one or more ionic liquids may be stirred or agitated during or after mixing. In other embodiments, the components of the lead halide solution, the Group 1 metal halide solution, and the ionic liquid may be added together into a single solution (along with one or more solvents) to form the lead halide precursor ink.

[0143] Then, the lead halide precursor ink including the ionic liquid can be deposited on the desired substrate. Suitable substrate layer can include any substrate layer previously confirmed in the present invention. As noted above, lead halide precursor ink can be deposited by various means, including but not limited to drop casting, spin casting, gravure coating, blade coating, reverse gravure coating, slit extrusion printing, screen printing or inkjet printing. In certain embodiments, the lead halide precursor ink can be spin-coated on the substrate at a speed of about 500rpm to about 10,000rpm, for a period of about 5 seconds to about 600 seconds. In one embodiment, the lead halide precursor ink can be spin-coated on the substrate in a two-step procedure. In some embodiments, an anti-solvent can be added to the substrate during one or more steps. For example, in one embodiment, the film precursor ink can be spin-coated with 1000rpm and 4000rpm for about 12 seconds and 25 seconds, respectively, and chlorobenzene anti-solvent can be added during the second step. The thin film precursor ink may be deposited on the substrate in an ambient atmosphere at a humidity range of about 0% relative humidity to about 50% relative humidity, about 0.01% relative humidity to about 50% relative humidity, about 0.1% relative humidity to about 50% relative humidity, or about 1% relative humidity to about 50% relative humidity. In some embodiments, the thin film precursor ink may be deposited on the substrate in an ambient atmosphere having a humidity greater than 0% relative humidity. The thin film precursor ink may then be deposited in an atmosphere substantially free of water (i.e., less than 30% relative humidity or 7 g H2O / m 3 ) The lead halide precursor ink is dried to form a thin film.

[0144] The lead halide precursor ink may then be thermally annealed at a temperature of about 20°C to about 300°C for a period of up to about 24 hours. In one embodiment, the film may be thermally annealed at a temperature of about 100°C for about thirty minutes. The perovskite material active layer may then be completed by a conversion process in which the precursor film is immersed or rinsed with a salt solution comprising a solvent or a mixture of solvents (e.g., DMF, isopropanol, methanol, ethanol, butanol, chloroform, chlorobenzene, dimethyl sulfoxide, water) and a salt at a concentration of 0.001M to 10M (e.g., methylammonium iodide, formamidine iodide, guanidine iodide, 1,2,2-triaminovinylammonium iodide, 5-aminopentanoic acid hydroiodide). In certain embodiments, the perovskite material film may also be thermally post-annealed in the same manner as in the first line of this paragraph.

[0145] Figure 7-11 The current-voltage and current density-voltage scans and related test data of photovoltaic devices incorporating perovskite materials formed using the ionic liquids of the present invention are shown. Figure 7-11 The scanned device is formed using the method described below.

[0146] According to this embodiment, the FTO substrate is first washed with ultrasonic detergent, deionized water, acetone and isopropanol, and then treated with UV / ozone cleaner for 15min. By spray pyrolysis, a diisopropyl di(acetylacetonato)titanate solution diluted in 2-propanol in a volume ratio of 1:18 is used at 500°C to deposit a dense layer of TiO2 (cp-TiO2) on FTO, and annealed in situ for 30 minutes. Then, a mesoporous TiO2 (mp-TiO2) solution composed of 1g TiO2 paste diluted in 10mL anhydrous ethanol solution is deposited on cp-TiO2 / FTO substrates by a one-step spin coating process at 4,500rpm for 20 seconds. After annealing at 125°C for 30 minutes, the deposited TiO2 film is gradually heated to 500°C in air, and then baked for 20 minutes. A SnO2 layer was then deposited on the substrate by spin coating a 0.1 M SnCl4 aqueous solution at 3,000 rpm for 20 seconds in a one-step process. Next, the substrate was transferred to a hot plate and kept at a temperature of 150°C to 190°C for one hour. The substrate was then treated with UV / ozone for 30 minutes.

[0147] Next, by PbI2 (1.35M), RbI (0.05M), CsI (0.05M), FAI (1.15M) and MACl (0.10M) are dissolved in the mixed solvent of DMF:DMSO of volume ratio 3:1 to prepare lead halide precursor solution (with or without ionic liquid). In this embodiment, solids are all weighed and added in the following order: PbI2, RbI, CsI, FAI and MACl. Next, DMF is added, followed by DMSO. In other embodiments, DMSO can be added before DMF.

[0148] For comparison purposes, the Fig.14 For the remaining devices, the ionic liquid of the present invention was added to the lead halide precursor solution in an amount of 0.5 mol%. Chloride, TFSI and tetraphenylborate anions were used to form ionic liquids including Formula 8 as cations. Figure 3 , Figure 5 and Figure 6 The perovskite material of the device is formed by using TFSI and chloride anions, respectively, and using an ionic liquid including Formula 9 as a cation. Figure 4 and Figure 7Perovskite materials for devices. Next, 25 μL of each lead halide precursor solution was spin-coated on the FTO / dense layer TiO2 / mesoporous layer TiO2 / SnO2 substrate using a two-step procedure running at 1,000 rpm and 4,000 rpm for 12 seconds and 25 seconds, respectively. During the second step, 750 μL of chlorobenzene was dispensed on the substrate. Next, the spin-coated film was annealed at 100°C for 30 minutes and allowed to cool to room temperature. Next, a PEAI solution (10 mg / 1 mL) diluted in IPA was spin-coated on the substrate at 4,000 rpm for 15 seconds. After the PEAI layer was deposited, 45 μL of the spiro-OMeTAD solution was deposited on the perovskite layer by spin coating at 4,000 rpm for 12 seconds. The spiro-OMeTAD solution was prepared by dissolving 4-tert-butylpyridine ("TBP"), Li-TFSI in acetonitrile, and Co[t-BuPyPz]3[TFSI]3 ("FK209") in acetonitrile in chlorobenzene at a molar ratio of 1:0.03:0.5:3.3.2 spiro-OMeTAD:FK209:Li-TFSI:TBP. Finally, a 70 nm gold contact layer was thermally evaporated as a counter electrode to complete the device fabrication.

[0149] Then, solar cell measurements were performed at room temperature to generate the current-voltage characteristics and other data of the perovskite solar cells shown in Figures 46-51 and Figure 57. 2 The metal holes mask the active area of ​​the solar cell to reduce the influence of scattered light. The open circuit voltage (Voc), short circuit current density (Jsc), fill factor (FF) and power conversion efficiency (PCE) of each ionic liquid perovskite solar cell and the control perovskite solar cell are listed in Table 6 below.

[0150] Table 6

[0151]

[0152] As can be seen in Table 6, the perovskite PV devices show an absolute improvement in device performance of about 1% compared to the control, while producing a more robust perovskite material that is resistant to water.

[0153] Figure 9-11 Scanning electron microscope images comparing perovskite PVs made with various ionic liquids with those made without ionic liquids are shown.

[0154] Many modifications, changes and variations of the described embodiments are possible without departing from the scope of the invention as defined in the claims.The present invention is not intended to be limited to the described embodiments, but rather has the full scope defined by the words of the following claims and their equivalents.

Claims

1. A method comprising: forming a perovskite precursor ink comprising a lead halide, an ionic liquid, a solvent, and a formamidine halide; depositing the perovskite precursor ink on a substrate; drying the perovskite precursor ink to form a perovskite precursor film; and The perovskite precursor film is annealed.

2. The method of claim 1, wherein the perovskite precursor film is a thin film.

3. The method of claim 1, wherein the ionic liquid comprises an organic cation.

4. The method according to claim 1, wherein the ionic liquid comprises an anion selected from the group consisting of a halide ion, bis(trifluoromethane)sulfonyl imide (TFSI), and a general formula [BR1R2R3R4] - The borate anion, wherein each of R1-R4 is selected from F, The group composed of Derivatives of the foregoing, and any combinations thereof.

5. The method of claim 1, wherein the lead halide comprises lead (II) iodide. The method of claim 1 , wherein the perovskite precursor ink is deposited on the substrate by spin coating.

7. The method of claim 1, wherein the perovskite precursor film is annealed at 100°C for 30 minutes. 8 . The method of claim 1 , wherein the perovskite precursor ink comprises the ionic liquid in an amount of about 0.01 mol % to about 10 mol % relative to lead atoms in the perovskite precursor ink.

9. A perovskite material prepared by a method comprising the following steps: forming a perovskite precursor ink comprising a lead halide, an ionic liquid, a solvent, and a formamidine halide; depositing the perovskite precursor ink on a substrate; drying the perovskite precursor ink to form a perovskite precursor film; and The perovskite film is annealed to form the perovskite material.

10. The perovskite material according to claim 9, wherein the perovskite precursor film is a thin film.

11. The perovskite material of claim 9, wherein the ionic liquid comprises an organic cation.

12. The perovskite material according to claim 9, wherein the ionic liquid comprises anions selected from the group consisting of halide ions, bis(trifluoromethane)sulfonyl imide (TFSI), and a general formula [BR1R2R3R4] - The borate anion, wherein each of R1-R4 is selected from F, The group composed of Derivatives of the foregoing, and any combinations thereof.

13. The perovskite material of claim 9, wherein the lead halide comprises lead (II) iodide.

14. The perovskite material of claim 9, wherein the perovskite precursor ink is deposited on the substrate by spin coating.

15. The perovskite material of claim 9, wherein the perovskite precursor film is annealed at 100°C for 30 minutes. 16 . The perovskite material according to claim 9 , wherein the perovskite precursor ink comprises the ionic liquid in an amount of about 0.01 mol % to about 10 mol % relative to lead atoms in the perovskite precursor ink.

17. A method comprising: forming a lead halide precursor ink comprising a Group 1 metal halide, a lead halide, an ionic liquid, and a solvent; depositing the lead halide precursor ink on a substrate; drying the lead halide precursor ink to form a lead halide film; and The lead halide film is annealed.

18. The method of claim 17, wherein the ionic liquid comprises a cation selected from the group consisting of ammonium, formamidine, guanidinium, ethylenetetramine cation, imidazolium cation, a cation of the general formula [R3R2R1PNPR4R5R6] + A compound having the general formula [R3R2R1PNPR4R5R6] + cations, and any combination thereof; Wherein each of R1-R6 is independently selected from the group consisting of: hydrogen, methyl, ethyl, propyl, butyl, pentyl, alkane, alkene, alkyne, alkyl halide, aromatic group, cyclic complex containing at least one nitrogen in the ring, sulfur-containing group, nitrogen-containing group, phosphorus-containing group, boron-containing group, organic acid and its ester or amide derivative thereof, amino acid, silicon-containing group, alkoxy group, halogen, pseudohalogen, and any combination thereof.

19. The method of claim 17, wherein the ionic liquid comprises a cation of the formula:

20. The method of claim 17, wherein the ionic liquid comprises a cation of the formula:

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