Ionic liquid perovskite device

Abstract

A method comprising the steps of forming a lead halide precursor ink comprising a Group 1 metal halide, lead halide, ionic liquid, and 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

Technical Field

[0001] This application claims the priority of 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 contents of which are hereby incorporated by reference in their entirety.

Background Art

[0002] The use of photovoltaic (PV) devices to generate electricity from solar energy or radiation offers many advantages, including, for example, power supply, low or zero emissions, power generation independent of the power grid, durable physical structures (without moving parts), stable and reliable systems, modular construction, relatively rapid installation, safe manufacturing and use, and favorable public opinion and acceptance of use.

Summary of the Invention

Problems to be Solved by the Invention

[0003] In certain embodiments, the method includes forming a lead halide precursor ink comprising a Group 1 metal halide, lead halide, ionic liquid, and 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.

Means for Solving the Problems

[0004] The features and advantages of the present disclosure will be readily understood by those skilled in the art. Many modifications are possible for those skilled in the art and such modifications are within the scope of the spirit of the present invention.

Brief Description of the Drawings

[0005]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

DETAILED DESCRIPTION

[0006] With various improvements in PV technologies compatible with organic, inorganic, and / or hybrid PV, it is expected that the costs of both organic PV and other PV will be further reduced. For example, in some solar cells such as perovskite PV solar cells, advantages of novel, cost-effective, and highly stable alternative components such as nickel oxide interface layers can be obtained. Further, various types of solar cells may significantly have chemical additives and other materials, which, among other advantages, are more cost-effective and durable than existing conventional options.

[0007] The present disclosure generally relates to compositions of materials, devices, and methods of use in photovoltaic cells for generating electrical energy from solar radiation. More specifically, the present disclosure relates to compositions of photoactive and other substances, as well as devices, methods of use, and methods of formation of such compositions of substances.

[0008] Some or all of the materials according to certain embodiments of the present disclosure may be significantly used in any organic or other electronic devices, and some examples of these include, but are not limited to, batteries, field effect transistors (FETs), light emitting diodes (LEDs), non-linear optical devices, transistors, ionizing radiation detectors, memristors, capacitors, rectifiers, and / or rectenna.

[0009] In some embodiments, the present disclosure may 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. The perovskite materials may be incorporated into one or more various aspects of PV or other devices. The perovskite materials according to some embodiments may have the general formula CMX3. Here, C includes one or more cations (e.g., amines, ammonium, phosphonium, group 1 metals, group 2 metals, and / or other cations or cationic compounds), M includes one or more metals (e.g., including 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. The perovskite materials according to various embodiments will be discussed in more detail below.

[0010] (Photovoltaic cells and other electronic devices) Some PV embodiments may be described by reference to exemplary drawings of perovskite material devices as shown in FIG. 1. An exemplary PV architecture according to some embodiments may be substantially in the form of a substrate - anode - IFL - active layer - IFL - cathode. The active layer of some embodiments may be photoactive and / or may include a photoactive material. As is known in the art, other layers and materials may be utilized within the cell. Further, it should be noted that the use of the term "active layer" does not mean to explicitly or implicitly limit or define the characteristics of other layers. For example, in some embodiments, one or both of the IFLs may be active as long as they can be semiconductors. In particular, referring to FIG. 1, a stereotypical general PV cell 1000 is shown, and the highly interfacial nature of some of the layers within the PV is shown. PV1000 represents a general architecture applicable to some PV devices, such as PV embodiments of perovskite materials. The PV cell 1000 includes a transparent substrate layer 1010 that may be glass (or a material similarly transparent to solar radiation), thereby allowing solar radiation to pass through this layer. Also, the transparent layer of some embodiments is also referred to as a superstrate or substrate, which may have any one or more of various rigid or flexible materials such as glass, polyethylene, polypropylene, polycarbonate, polyimide, PMMA, PET, PEN, Kapton, or quartz. Generally, the term substrate is used when referring to the material on which the device is deposited during manufacturing. The 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 showing both p - type material characteristics and n - type material characteristics, and / or an intrinsic semiconductor showing neither n - type nor p - type characteristics. In some embodiments, the photoactive layer 1040 may be the perovskite material described in this application. The active layer, or the photoactive layer 1040 as shown in FIG. 1, is sandwiched between two conductive electrode layers 1020 and 1060.In FIG. 1, the electrode layer 1020 may be a transparent conductor such as tin-doped indium oxide (ITO material) or other materials described in the present application. In other embodiments, the second substrate 1070 and the second electrode 1060 may be transparent. As described above, the active layer in some embodiments does not necessarily have to be photoactive, but in the device shown in FIG. 1, it is photoactive. The electrode layer 1060 may be an aluminum material or other metal, or other conductive materials such as carbon. Other materials known in the art may also be used. The cell 1100 also includes the IFL 1030 shown in the example of FIG. 1. The IFL can assist in charge separation. In other embodiments, the IFL 1030 may include a multilayer IFL. For example, a perovskite material device may include 0, 1, 2, 3, 4, 5, or more interface layers (such as the exemplary devices of FIGS. 2-4 of U.S. Patent No. 11,171,290, which are hereby incorporated by reference in their entirety). Also, an IFL 1050 may be present adjacent to the electrode 1060. In some embodiments, in addition to or alternatively to this, the IFL 1050 adjacent to the electrode 1060 may include a multilayer IFL. In some embodiments, the IFL on the cathode side of the device (e.g., the IFL 1050 shown in FIG. 1) may be p-type, and the IFL on the anode side of the device (e.g., the IFL 1030 shown in FIG. 1) 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 the electrical leads by a discharge unit such as the electrodes 1060 and 1020, and a battery, motor, capacitor, electrical grid, or any other electrical load. Additional embodiments of devices that may be used in accordance with the present disclosure are found in U.S. Patents Nos. 9,425,396 and 11,186,495, and U.S. Patent Publication No. 2018 / 0301288, the disclosures of which are hereby incorporated by reference in their entirety.

[0011] Various embodiments of the present disclosure provide improved materials and / or designs in various aspects of solar cells and other devices, including, in particular, active materials (including hole transport layers and / or electron transport layers), interface layers, and overall device designs.

[0012] (Perovskite material) Perovskite materials may be incorporated into one or more aspects of PV or other devices. Perovskite materials according to some embodiments generally have the formula C w M y X z where C has one or more cations (e.g., amines, ammonium, phosphonium, Group 1 metals, Group 2 metals, and / or other cations or cationic compounds), M has one or more metals (e.g., including 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 has one or more anions, and w, y, and z represent real numbers between 1 and 20. In some embodiments, C may include 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 bonded to both the cation C and the metal M.

[0013] In one embodiment, C may have ammonium and an organic cation of the general formula [NR4] + where the R groups may be the same or different groups. Suitable R groups include, but are not limited to, hydrogen, methyl, ethyl, propyl, butyl, pentyl groups, or their isomers; any alkane, alkene, or alkyne C x H y , where x = 1 to 20 and y = 1 to 42, and which is cyclic, branched, or linear; halogenated alkyl, C x H y X z, where x = 1 to 20, y = 0 to 42, z = 1 to 42, and X = F, Cl, Br, or I; any aromatic group (e.g., phenyl, alkylphenyl, alkoxyphenyl, pyridine, naphthalene); 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, thiol, alkyl sulfide); any nitrogen-containing group (nitroxide, amine); any phosphorus-containing group (phosphate); any boron-containing group (e.g., boronic acid); any organic acid (e.g., acetic acid, propanoic acid); and their ester or amide derivatives; any amino acid including α, β, γ, and larger derivatives (e.g., glycine, cysteine, proline, glutamic acid, arginine, serine, histidine, 5-ammonium valeric acid); any silicon-containing group (e.g., siloxane); and any alkoxy or group -OC x H y , where x = 0 to 20 and y = 1 to 42 are included.

[0014] In certain embodiments, C may include formamidinium, an organic cation of the general formula [R2NCRNR2] + , where 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 in the previous paragraph.

[0015]

Chemical formula

[0016] ​ [Chemical formula] Formula 2 In certain embodiments, C may include guanidinium, an organic cation having the general formula [(R2N)2C=NR2] + . Here, the R groups may be the same or different. Suitable R groups include, but are not limited to, any of the R groups listed above in the previous paragraph.

[0017] [Chemical formula] Formula 3 Formula 3 shows the structure of a guanidinium cation having the general formula [(R2N)2C=NR2] as described above + . Formula 4 shows examples of the structures of several guanidinium cations that can act as cation "C" in a perovskite material.

[0018] [Chemical formula] TIFF2025518472000006.tif99138 Formula 4 In certain embodiments, C may include ethenetetramine cation, an organic cation having the general formula [(R2N)2C=C(NR2)2] + . Here, the R groups may be the same or different. Suitable R groups include, but are not limited to, any of the R groups listed in the previous paragraph.

[0019] [Chemical formula] Formula 5 Formula 5 shows the general formula [(R2N)2C=C(NR2)2] as described above +Shows the structure of the ethylenetetramine cation having [it]. Formula 6 shows examples of the structures of several ethylenetetraamine ions that can act as cation "C" in the perovskite material.

[0020]

Chem.

[0021]

Chem.

[0022] In certain embodiments, X may include one or more halides. In certain embodiments, X may additionally or alternatively include a Group 16 anion. In certain embodiments, the Group 16 anion may be an oxide, sulfide, selenide, or telluride. In certain embodiments, X may be F, Cl, Br, I, SCN, CN, or any other pseudohalide. Other acceptable non-halide anions include, but are not limited to, nitrate, nitrite, carboxylate, acetate, acetylacetonate, formate, oxalate, sulfate, sulfite, thiosulfate, phosphate, tetrafluoroborate, hexafluorophosphate, tetra(perfluorophenyl)borate, hydride, oxide, peroxide, hydroxide, nitride, arsenate, arsenite, perchlorate, carbonate, bicarbonate, chromate, dichromate, iodate, bromate, chlorate, chlorite, hypochlorite, hypobromite, cyanide, cyanate, isocyanate, fulminate, thiocyanate, isothiocyanate, azide-based, tetracarbonylcobaltate, carbamoyldicyanomethanide, dicyanonitrosomethanide, dicyanamide, tricyanomethanate, amide, and permanganate.

[0023] For illustrative purposes and not by way of limitation, the following, formula C w M y X z Exemplary embodiments of perovskite materials having will be discussed. In one embodiment, the perovskite material may have the following empirical formula CMX3. Here, M includes one of the aforementioned metals, C includes one or more of the aforementioned cations, Group 1 metals, Group 2 metals, and / or other cations or cationic compounds, and X includes one or more of the aforementioned anions.

[0024] In another embodiment, the perovskite material may have the empirical formula C’M2X6. Here, C’ includes a cation having a 2+ charge, which includes one or more of the aforementioned cations, butanediammonium, Group 1 metals, Group 2 metals, and / or other cations or cationic compounds.

[0025] In another embodiment, the perovskite material may have the empirical formula C’MX4. Here, C’ includes a cation having a +2 charge, which includes one or more of the aforementioned cations, butanediammonium, group 1 metals, group 2 metals, and / or other cations or cationic compounds. In such an embodiment, the perovskite material may have a 2D structure.

[0026] In one embodiment, the perovskite material may have the following empirical formula: C3M2X9, CM2X7, or C2MX4. Here, C includes one or more of the aforementioned cations, group 1 metals, group 2 metals, and / or other cations or cationic compounds.

[0027] Also, the perovskite material may have a mixed ion formulation. Here, C, M, or X includes two or more chemical 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.

[0028] In one example, the perovskite material in the active layer may have the general formula CMX 3-y X’y (0 ≧ y ≧ 3). Here, C includes one or more cations (e.g., amines, ammonium, group 1 metals, group 2 metals, formamidinium, guanidinium, ethenetetramine, phosphonium, imidazolium, and / or other cations or cationic compounds), M includes 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’ include one or more anions. In one embodiment, the perovskite material is CPbI 3-y Cl ymay have. In another example, the perovskite material in the active layer may have the general formula C 1-x C’ x MX3 (0 ≧ x ≧ 1). Here, C and C’ include one or more cations as described above. In another example, the perovskite material in the active layer may have the general formula CM 1-z M’ z X3 (0 ≧ z ≧ 1). Here, M and M’ include one or more metals as described above. In one example, the perovskite material in the active layer may have the general 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). Here, C and C’ include one or more cations as described above, M and M’ include one or more metals as described above, and X and X’ include one or more anions as described above.

[0029] For illustrative purposes and not intended to be limiting, exemplary embodiments of the perovskite material are, for example, Cs 0.1 FA 0.9 Pb(I 0.9 Cl 0.1 )3; Rb 0.1 FA 0.9 Pb(I 0.9 Cl 0.1 )3, Cs 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 Rb 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.

[0030] (Formation of the Perovskite Material Active Layer) In one embodiment, the perovskite material may be deposited on a substrate layer as an active layer in a PV device using the steps described below, for example, by blade coating, drop casting, spin casting, slot die printing, screen printing, or inkjet printing.

[0031] First, a lead halide precursor ink is formed. In a controlled atmosphere environment (e.g., in a controlled atmosphere box with a port hole including gloves, material manipulation in an air-free environment is possible), an amount of lead halide may be collected in a clean and dry container. Suitable lead halides include, but are not limited to, lead(II) iodide, lead(II) bromide, lead(II) chloride, and lead(II) fluoride. The lead halide may contain a single type of lead halide or may contain a mixture of lead halides in an exact ratio. In one embodiment, the lead halide mixture may contain any binary, ternary, or quaternary ratio of iodide, bromide, chloride, or fluoride from 0.001 to 100 mol%. In one embodiment, the lead halide mixture may have lead(II) chloride and lead(II) iodide in a mol:mol ratio of about 10:90. In other embodiments, the lead halide mixture may contain lead(II) chloride and lead(II) iodide in a mol:mol ratio of about 5:95, about 7.5:92.5, or about 15:85.

[0032] 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 include any combination of lead (II) or lead (IV) with the following anions: nitrate, nitrite, carboxylate, acetate, acetylacetonate, formate, oxalate, sulfate, sulfite, thiosulfate, phosphate, tetrafluoroborate, hexafluorophosphate, tetra(perfluorophenyl)borate, hydride, oxide, peroxide, hydroxide, nitride, arsenate, arsenite, perchlorate, carbonate, bicarbonate, chromate, dichromate, iodate, bromate, chlorate, chlorite, hypochlorite, hypobromite, cyanide, cyanate, isocyanate, fulminate, thiocyanate, isothiocyanate, azide, tetracarbonylcobaltate, carbamoyldicyanomethanide, dicyanonitrosomethanide, dicyanamide, tricyanomethanate, amide, and permanganate.

[0033] Furthermore, the precursor ink may have a lead (II) salt or lead (IV) salt in a molar ratio of 0 to 100% with respect 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, Zr as salts of the aforementioned anions.

[0034] Next, a solvent may be added to the container to dissolve the lead solid and 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 further 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 have a ratio of 2-methoxyethanol and acetonitrile to DMF of about 1:100 to about 1:1, or about 1:100 to about 1:5, by volume. In certain embodiments, the solvent may have a ratio of 2-methoxyethanol and acetonitrile to DMF of at least about 1:100, by volume.

[0035] In certain embodiments, the lead solid may be dissolved at a temperature between about 20°C and about 150°C. In one embodiment, the lead halide solid is dissolved at about 85°C. The lead solid may be dissolved in the time required to form a solution, which may occur over 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 between about 0.001M and about 10M, or about 1M.

[0036] If necessary, specific additives may be added to the lead halide precursor ink to affect the crystallinity and stability of the final perovskite. In some embodiments, the lead halide precursor ink may further include an amino acid (e.g., 5-aminovaleric acid, histidine, glycine, lysine), an amino acid hydrohalide (e.g., 5-aminovalerate hydrochloride), an IFL surface modification (SAM) agent (such as those previously discussed in this application), or combinations thereof. Suitable amino acids for the lead halide precursor ink 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, formamidinium chloride may be added to the lead halide precursor ink. In other embodiments, halides of any of the cations previously discussed in this application may be used. In some embodiments, for example, a combination of additives including a combination of formamidinium chloride and 5-aminovalerate hydrochloride may be added to the lead halide precursor ink.

[0037] In certain embodiments, additives including formamidinium chloride and / or 5-aminovalerate 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 additives may be added at a concentration of from about 1 nM to about 1 M, from about 1 μM to about 1 M, or from about 1 μM to about 1 mM.

[0038] If necessary, in certain embodiments, water may be added to the lead halide precursor ink. By way of explanation and not to limit the present disclosure to any particular theory or mechanism, the presence of water affects perovskite thin film crystal growth. Under normal environmental conditions, water can be absorbed as vapor from the air. However, by directly adding water to the lead halide precursor ink at a specific concentration, the crystallinity of the perovskite PV can be controlled. Suitable water includes distilled water, deionized water, or any other water source that is substantially free of contaminants (including minerals). Based on the light I-V sweep, it has been observed that the power conversion efficiency of the perovskite PV can be increased by about three times with the addition of water compared to a completely dry device.

[0039] Water 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, water may be added at a concentration of from about 1 nL / mL to about 1 mL / mL, from about 1 μL / mL to about 0.1 mL / mL, or from about 1 μL / mL to about 20 μL / mL.

[0040] Next, the lead halide precursor ink may be deposited on a desired substrate. Suitable substrate layers may include any of the substrate layers previously identified in the present disclosure. As described above, the lead halide precursor ink may be deposited by various means, including, but not limited to, drop casting, spin coating (spin casting), slot die printing, inkjet printing, gravure printing, screen printing, sputtering, PE-CVD, atomic layer deposition, thermal evaporation, spray coating, and any combination thereof. In certain embodiments, the lead halide precursor ink may be spin-coated onto the substrate at a rate of from about 500 rpm to about 10,000 rpm for a time period of from about 5 seconds to about 600 seconds. In one embodiment, the lead halide precursor ink may be spin-coated onto the substrate at about 3000 rpm for about 30 seconds. The lead halide precursor ink may be deposited on the substrate in an ambient atmosphere in a humidity range of from about 0% relative humidity to about 50% relative humidity. Next, the lead halide precursor ink may be dried in a substantially water-free atmosphere, i.e., at a relative humidity of less than 30%, to form a thin film.

[0041] Next, the thin film may be thermally annealed at a temperature of from about 20°C to about 300°C for up to about 24 hours. In one embodiment, the thin film may be thermally annealed at a temperature of about 50°C for about 10 minutes. Thereafter, the perovskite material active layer may be completed by a conversion process. In this process, the precursor film is immersed or rinsed with a solution containing a solvent, or a mixture of solvents (e.g., DMF, isopropyl alcohol, methanol, ethanol, butanol, chloroform, chlorobenzene, dimethyl sulfoxide, water) at a concentration between 0.001 M and 10 M, and a salt (e.g., methylammonium iodide, formamidinium iodide, guanidinium iodide, 1,2,2-triaminovinylammonium iodide, 5-amino valeric acid hydroiodide). In certain embodiments, the thin film may be thermally post-annealed in the same manner as the first line of this paragraph.

[0042] In one embodiment, a lead salt precursor may be deposited on a substrate to form a lead salt thin film. The substrate may have a temperature approximately equal to the ambient temperature or a controlled temperature between 0°C and 500°C. The lead salt precursor may be deposited by any of the various methods described above for the lead halide precursor ink. In one embodiment, the deposition of the lead salt precursor may have a sheet-to-sheet or roll-to-roll manufacturing method. The deposition of the lead salt precursor may be carried out in various atmospheres under ambient pressure or at atmospheric pressure or a pressure lower than the ambient (e.g., from 1 mTorr to 500 mTorr). The deposition atmosphere may be ambient air, a controlled humidity environment (e.g., 0 to 100 gH2O / m 3 of gas), pure argon, pure nitrogen, pure oxygen, pure hydrogen, pure helium, pure neon, pure krypton, pure CO2, or any combination of the aforementioned gases. The controlled humidity environment may include an environment in which the absolute humidity or relative humidity % is maintained at a fixed value, or an environment in which the absolute humidity or relative humidity % changes according to a predetermined set point or a predetermined function. In certain embodiments, the deposition may be carried out in a controlled humidity environment having a relative humidity % of 0% or more and 50% or less. In other embodiments, the deposition may be carried out in a controlled humidity environment containing a gas of 0 gH2O / m 3 or more and 20 gH2O / m 3 or less. Unless otherwise specified, any annealing or deposition step described in the present application may be carried out under the aforementioned conditions.

[0043] The lead salt precursor may be a liquid, gas, solid, or a combination of these states of matter such as a solution, suspension, colloid, foam, gel, or aerosol. In certain embodiments, the lead salt precursor may be a solution containing one or more solvents. For example, the lead salt precursor may have one or more of 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 contain a single lead salt (e.g., lead(II) iodide, lead(II) thiocyanate), or any combination disclosed herein (e.g., PbI2 + PbCl2; PbI2 + Pb(SCN)2). The lead salt precursor may also have one or more additives such as an amino acid (e.g., 5-aminovaleric acid hydroiodide), 1,8-diiodooctane, 1,8-dithiooctane, formamidinium halide, acetic acid, trifluoroacetic acid, methylammonium halide, or water. The lead salt precursor may be dried in a substantially water-free atmosphere, i.e., an atmosphere with a relative humidity of less than 30%, and a thin film may be formed. Next, the lead salt thin film may be thermally annealed for the same time under the same conditions as described above for the lead halide precursor ink thin film. The annealing environment may have the same pressure and atmosphere as the aforementioned lead salt deposition environment and conditions. In certain embodiments, the annealing treatment may be carried out in a controlled humidity environment having a relative humidity of 0% or more and 50% or less. In other embodiments, the annealing treatment may be carried out in a controlled humidity environment containing from 0 gH2O / m 3 gas to 20 gH2O / m 3 gas and below.

[0044] After the lead salt precursor is deposited, a second salt precursor (e.g., formamidinium iodide, formamidinium thiocyanate, guanidinium thiocyanate) may be deposited on the lead salt thin film. The lead salt thin film may have a temperature approximately equal to the ambient temperature, or may have a controlled temperature between 0°C and 500°C. In some embodiments, the second salt precursor may be deposited at ambient temperature or at an elevated temperature between about 25°C and 125°C. The second salt precursor may be deposited by any of the methods described above with respect to the lead halide precursor ink. The deposition of the second salt precursor may be carried out under the same environment and the same conditions as described above for the first halide precursor.

[0045] In certain embodiments, the second salt precursor may be a solution containing one or more solvents (e.g., one or more of the solvents described above with respect to the first lead salt precursor).

[0046] After the deposition of the lead salt precursor and the second salt precursor, the substrate may be annealed. By annealing the substrate, the lead salt precursor and the second salt precursor can be converted into a perovskite material (e.g., FAPbI3, GAPb(SCN)3, FASnI3). The annealing process may be carried out under the same environment and the same conditions as the lead salt deposition environment described above. In certain embodiments, the annealing process may be carried out in a controlled humidity environment having a relative humidity of 0% or more and 50% or less. In other embodiments, the annealing process may be carried out in a controlled humidity environment containing the following gas with 0 gH2O / m 3 or more and 20 gH2O / m 3 or less. In some embodiments, the annealing process may be carried out at a temperature between 50°C and 300°C.

[0047] For example, in certain embodiments, the FAPbI3 perovskite material may be formed by the following process. First, a lead(II) halide precursor with a molar ratio of PbI2 to PbCl2 dissolved in anhydrous DMF of about 90:10 may be deposited on a substrate by spin coating or slot die printing. The lead halide precursor ink may be dried for about 1 hour (+15 minutes) in a substantially water-free atmosphere, i.e., an environment with a relative humidity of less than 30%, to form a thin film. The thin film may then be thermally annealed at a temperature of about 50 °C (+10 °C) for about 10 minutes. Next, a formamidinium iodide precursor containing formamidinium iodide at a concentration of 25 - 60 mg / mL dissolved in anhydrous isopropyl alcohol may be deposited on the lead halide thin film by spin coating or slot die printing. After depositing the lead halide precursor and the formamidinium iodide precursor, the substrate may be annealed at a relative humidity of about 25% (about 4 to 7 gH2O / m 3 air) and between about 125 and 200 °C to form a formamidinium lead (FAPbI3) perovskite material.

[0048] In another embodiment, the perovskite material may include C’CPbX3, where C’ is one or more Group 1 metals (e.g., Li, Na, K, Rb, Cs). In a particular embodiment, M’ may be cesium (Cs). In yet another embodiment, the perovskite material may include C’ v C w Pb y X z where C’ is one or more Group 1 metals, and v, w, y, and z represent real numbers between 1 and 20. In one embodiment, the perovskite material may be deposited on a substrate layer as an active layer in a PV device, for example, by drop casting, spin casting, gravure coating, blade coating, reverse gravure coating, slot die printing, screen printing, or inkjet printing.

[0049] First, a lead halide solution is formed. The lead halide solution may be prepared by any method and similar composition as the aforementioned lead halide precursor ink.

[0050] Other lead salt precursors (e.g., those described above for the lead halide precursor ink) may be used with or instead of the lead halide salt to form a lead salt solution.

[0051] Next, a Group 1 metal halide solution is formed. An amount of Group 1 metal halide may be collected 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 comprise a single type of Group 1 metal halide or may comprise a mixture of Group 1 metal halides in an exact ratio.

[0052] Alternatively, other Group 1 metal salt precursors may be used with or in place of the Group 1 metal halide salts to form a Group 1 metal salt solution. Suitable Group 1 precursor metal salts may include any combination of a Group 1 metal and the following anions: nitrate, nitrite, carboxylate, acetate, formate, oxalate, sulfate, sulfite, thiosulfate, phosphate, tetrafluoroborate, hexafluorophosphate, tetra(perfluorophenyl)borate, hydride, oxide, peroxide, hydroxide, nitride, arsenate, arsenite, perchlorate, carbonate, bicarbonate, chromate, dichromate, iodate, bromate, chlorate, chlorite, hypochlorite, hypobromite, cyanide, cyanate, isocyanate, fulminate, thiocyanate, isothiocyanate, azide, tetracarbonylcobaltate, carbamoyldicyanomethanide, dicyanonitrosomethanide, dicyanamide, tricyanomethanate, amide, and permanganate.

[0053] Next, a solvent may be added to the container to dissolve the Group 1 metal halide solid and 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 from 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 as long as necessary to form a solution, which may be carried out over a period of up to about 72 hours. The resulting solution forms a Group 1 metal halide solution. In certain embodiments, the Group 1 metal halide solution may have a Group 1 metal halide concentration between about 0.001 M and about 10 M, or about 1 M. In certain embodiments, the Group 1 metal halide solution may further have an amino acid (e.g., 5-aminovaleric acid, histidine, glycine, lysine), an amino acid hydrohalide (e.g., 5-aminovalerate hydrochloride), an IFL surface modification (SAM) agent (such as those previously discussed herein), or combinations thereof.

[0054] Next, a lead halide solution and a Group 1 metal halide solution are mixed 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 that is between 0% and 25% of the molar concentration of the lead halide. In certain embodiments, the thin film precursor ink may have a molar concentration of the Group 1 metal halide such that it is 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.

[0055] Next, the thin film precursor ink may be deposited on a desired substrate via any of the deposition means described above. Suitable substrate layers may include any of the substrate layers specifically identified earlier in this disclosure. In some embodiments, the thin film precursor ink may be spin-coated onto the substrate at a speed of from about 500 rpm to about 10,000 rpm for a time of from about 5 seconds to about 600 seconds. In one embodiment, the thin film precursor ink may be spin-coated onto the substrate at about 3000 rpm for about 30 seconds. The thin film precursor ink may be deposited on the substrate in an ambient atmosphere having a humidity range of from about 0% relative humidity to about 50% relative humidity. Next, the thin film precursor ink is dried in an atmosphere that is substantially free of water, i.e., an atmosphere having a relative humidity of less than 30% or less than 7 g H2O / m 3 and a thin film is formed.

[0056] Next, the thin film may be thermally annealed at a temperature of about 20°C to about 300°C for up to about 24 hours. In one embodiment, the thin film may be thermally annealed at a temperature of about 50°C for about 10 minutes. Next, the perovskite material active layer may be completed by a conversion process in which the precursor film is immersed or rinsed in a salt solution containing a solvent, or a mixture of solvents (e.g., DMF, isopropyl alcohol, methanol, ethanol, butanol, chloroform, chlorobenzene, dimethyl sulfoxide, water) and a salt (e.g., methylammonium iodide, formamidinium iodide, guanidinium iodide, 1,2,2-triaminovinylammonium iodide, 5-aminovaleric acid hydroiodide) at a concentration of 0.001M to 10M. Also, in certain embodiments, the perovskite material thin film may be thermally post-annealed in the same manner as the first line of this paragraph.

[0057] In one embodiment, the salt solution may be prepared by collecting the salt in a clean, dry container in a controlled atmosphere environment. Suitable salts include, but are not limited to, methylammonium iodide, formamidinium iodide, guanidinium iodide, imidazolium iodide, ethenetetramine iodide, 1,2,2-triaminovinylammonium iodide, and 5-aminovaleric acid hydroiodide. Other suitable salts may include any of the organic cations described above in the chapter entitled "Perovskite Materials". The salt may have a single chemical species of salt or may have an exact ratio of salt mixtures. Next, a solvent may be added to the container, the salt solid may be dissolved, and a salt solution may be formed. Suitable solvents include those listed in the previous paragraph and combinations thereof. In one embodiment, formamidinium iodide salt solid is dissolved in isopropanol. The salt solid may be dissolved at a temperature between about 20°C and about 150°C. In one embodiment, the salt solid is dissolved at room temperature (i.e., about 25°C). The salt solid may be dissolved for a sufficiently long time to form a solution, which may be carried out over a period of up to about 72 hours. The resulting solution forms a salt solution. In one embodiment, the salt solution may have a salt concentration between about 0.001M and about 10M. In one embodiment, the salt solution has a salt concentration of about 1M.

[0058] For example, by using the aforementioned process with a lead(II) iodide solution, a cesium iodide solution, and a methylammonium iodide (MA) salt solution, a perovskite material having the general formula Cs i MA 1-i PbI3 may be obtained. Here, i is equal to a number between 0 and 1. As another example, by using a lead(II) iodide solution, a rubidium iodide solution, and a formamidinium iodide (FA) salt solution, a perovskite material having the general formula Rb i FA 1-i PbI3 is obtained. Here, i is equal to a number between 0 and 1. As another example, when using a lead(II) iodide solution, a cesium iodide solution, and a formamidinium iodide (FA) salt solution, Cs i FA 1-iA perovskite material having the general formula PbI3 is obtained. Here, i is equal to a number between 0 and 1. As another example, when a lead(II) iodide solution, a potassium iodide solution, and a formamidinium iodide (FA) salt solution are used, a perovskite material having the general formula K i FA 1-i PbI3 can be obtained. Here, i is equal to a number between 0 and 1. As another example, by using a lead(II) iodide-sodium chloride mixed solution, a cesium iodide solution, and a formamidinium iodide (FA) salt solution, a perovskite material having the general formula Na i FA 1-i PbI3 can be obtained. Here, i is equal to a number between 0 and 1. As another example, by using a lead(II) iodide-lead(II) chloride mixed solution, a cesium iodide solution, and a formamidinium iodide (FA) salt solution, a perovskite material having the chemical formula Cs i FA 1-i Pb 3-y Cl y can be obtained. Here, i is equal to a number between 0 and 1, and y represents a number between 0 and 3.

[0059] In certain embodiments, the foregoing lead halide solution may have a molar ratio of PbI2 to PbCl2 of 90:10. By the foregoing method, a cesium iodide (CsI) solution may be added to the lead halide solution to form a thin film precursor ink having 10 mol% CsI. Using this thin film precursor solution, an FAPbI3 perovskite material may be manufactured by the method described above. As described above, when cesium ions are added via the CsI solution, chloride anions and cesium atoms may be incorporated into the FAPbI3 crystal lattice. This can result in a greater degree of lattice contraction compared to the case where cesium or rubidium ions are added without adding chloride ions as described above. Table 1 below shows the lattice constants of the FAPbI3 perovskite material in the case of containing 10 mol% rubidium and 20 mol% chloride (for example, 10 mol% PbCl2), 10 mol% cesium, and 10 mol% cesium and 20 mol% chloride. Here, the mol% concentration represents the concentration of the additive relative to the lead atoms in the lead halide solution. As can be seen from Table 1, the FAPbI3 perovskite material added with cesium and chloride has a smaller lattice constant than the other two perovskite material samples.

[0060]

Table 1

[0061]

Table 2

[0062]

Table 3

[0063]

Table 4

[0064]

Table 5

[0065] In certain embodiments, the ionic liquid may contain a salt of the general formula AB, where A is one or more cations and B is one or more anions. In certain embodiments, A may include ammonium, the organic cation of the general formula [NR4] + where the R groups may be the same or different groups. Suitable R groups include, but are not limited to, the following: hydrogen, methyl, ethyl, propyl, butyl, pentyl groups, or their isomers; any alkane, alkene, or alkyne C x H y , where x = 1 to 20, y = 1 to 42, cyclic, branched or straight chain; halogenated alkyl, C x H y X z , where x = 1 to 20, y = 0 to 42, z = 1 to 42, X = F, Cl, Br, or I; any aromatic group (e.g., phenyl, alkylphenyl, alkoxyphenyl, pyridine, naphthalene); cyclic complexes 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, thiol, alkyl sulfide); any nitrogen-containing group (nitroxide, amine); any phosphorus-containing group (phosphate); any boron-containing group (e.g., boronic acid); any organic acid (e.g., acetic acid, propanoic acid); and their ester or amide derivatives; any amino acid containing α, β, γ, and larger derivatives (e.g., glycine, cysteine, proline, glutamic acid, arginine, serine, histidine, 5-ammonium valeric acid); any silicon-containing group (e.g., siloxane); any alkoxy or group -OC x H y , where x = 0 to 20, y = 1 to 42; and any halide or pseudohalide: F, Cl, Br, I, SCN, or CN.

[0066] In one embodiment, A of the ionic liquid may contain formamidinium, an organic cation of the general formula [R2NCRNR2] + Here, the R groups may be the same or different. Suitable R groups include, but are not limited to, any R group in the previous paragraph.

[0067]

Chemical formula

[0068]

Chemical formula

[0069]

Chemical formula

[0070]

Chemical formula

[0071]

Chemical Structure

[0072]

Chemical Structure

[0073]

Chemical Structure

[0074]

Chemical Structure

[0075]

Chemical Structure

[0076]

Chemical formula

[0077]

Chemical formula

[0078]

Chemical formula

[0079] Formula 12 shows an exemplary structure that can act as cation "A" in an ionic liquid.

[0080]

Chemical formula

[0081] In certain embodiments, the anion B of the ionic liquid may have one or more halides (e.g., chloride). In certain embodiments, B may additionally or alternatively include a Group 16 anion. In certain embodiments, the Group 16 anion may be an oxide, sulfide, selenide, or telluride. In certain embodiments, B may have, but is not limited to, F, Cl, Br, I, SCN, CN, or any other pseudohalide. Other acceptable non-halide anions include, but are not limited to, nitrate, nitrite, carboxylate, acetate, acetylacetonate, formate, oxalate, sulfate, sulfite, thiosulfate, phosphate, tetrafluoroborate, hexafluorophosphate, tetra(perfluorophenyl)borate, hydride, oxide, peroxide, hydroxide, nitride, arsenate, arsenite, perchlorate, carbonate, bicarbonate, chromate, dichromate, iodate, bromate, chlorate, chlorite, hypochlorite, hypobromite, cyanide, cyanate, isocyanate, fulminate, thiocyanate, isothiocyanate, azide-based, tetracarbonylcobaltate, carbamoyldicyanomethanide, dicyanonitrosomethanide, dicyanamide, tricyanomethanate, amide, and permanganate. In certain embodiments, B may include one or more of bis(trifluoromethane)sulfonimide (TFSI) and tetraphenylborate.

[0082] In certain embodiments, B may include a borate anion of the general formula [BR1R2R3R4] - wherein R1 to R4 may be the same or different groups. Suitable R groups may include, but are not limited to, the following: halide or pseudohalide (e.g., F, Cl, Br, I, SCN, and CN), alkyl halide, Cx H y X z , where x = 1 - 20, y = 0 - 42, z = 1 - 42, X = F, Cl, Br, or I; any aromatic group (e.g., phenyl, alkylphenyl, alkoxyphenyl, pyridine, naphthalene); and a halide-substituted aromatic group (e.g., pentafluorophenyl). In certain embodiments, one or more R groups may be F or may have:

[0083]

Chemical formula

[0084]

Chemical formula

[0085] The ionic liquid may be used in any of the steps of forming the perovskite materials and layers discussed in this disclosure. Having the benefit of this disclosure, one of ordinary skill in the art can understand the steps in which the ionic liquid is incorporated and beneficial for perovskite material formation. For example, in certain embodiments, one or more ionic liquids may be added directly to the perovskite precursor ink, added to one or more solvents used in the perovskite formation process, added to one or more salt precursors, and / or added to one or more Group 1 metal halide solutions. In certain embodiments, one or more ionic liquids may be added to a solution containing one or more Group 1 metals and lead halide. In some embodiments, the ionic liquid may be added to the perovskite precursor solution prior to deposition and annealing.

[0086] The ionic liquid may be added to a solution (e.g., a lead halide precursor ink) at various concentrations depending on the desired properties of the resulting perovskite material. In one embodiment, the ionic liquid may be added at a concentration of from about 0.05 to about 10 mol%. Here, 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 may be added at a concentration of from about 0.01 to about 5 mol%, or from about 0.05 to about 1 mol%. In some embodiments, the ionic liquid may be added at a concentration of less than 10 mol%, less than 5 mol%, or less than 1 mol%.

[0087] In some embodiments, the perovskite material formed using the ionic liquid may have a mixed ion formulation in which C, M, or X comprises two or more chemical species. For example, the perovskite material may be CMX 3-x X’ x (0 ≧ x ≧ 3). Here, C comprises one or more cations (e.g., amines, ammonium, methylammonium, group 1 metals, group 2 metals, formamidinium, guanidinium, ethanetetramine, phosphonium, imidazolium, and / or other cations or cationic 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 certain embodiments, C may be Rb, Cs, formamidinium, and methylammonium. In some embodiments, the perovskite material may be CPbI 3-y Cl y and may be deposited on a substrate layer as an active layer in a PV device using the steps described below, for example, by drop casting, spin casting, gravure coating, blade coating, reverse gravure coating, slot die printing, screen printing, or inkjet printing.

[0088] An example of forming a perovskite material containing an ionic liquid will be described below. First, a lead halide solution is formed. An amount of lead halide may be collected in a clean and dry container under a controlled atmosphere environment. Suitable lead halides include, but are not limited to, lead(II) iodide, lead(II) bromide, lead(II) chloride, and lead(II) fluoride. The lead halide may contain a single type of lead halide or may contain a mixture of lead halides in an exact ratio. In one embodiment, the lead halide may contain lead(II) iodide. In a particular embodiment, the lead halide mixture may contain any binary, ternary, or quaternary ratio of iodide, bromide, chloride, or fluoride from 0.001 to 100 mol%. In one embodiment, the lead halide mixture may contain lead(II) chloride and lead(II) iodide in a ratio of about 10:90 mol:mol. In other embodiments, the lead halide mixture may contain lead(II) chloride and lead(II) iodide in mol:mol ratios of about 5:95, about 7.5:92.5, or about 15:85. Alternatively, other lead salt precursors may be used with or instead of the lead halide salt to form a lead salt solution. Suitable precursor lead salts may include any combination of lead(II) or lead(IV) with the following anions: nitrate, nitrite, carboxylate, acetate, formate, oxalate, sulfate, sulfite, thiosulfate, phosphate, tetrafluoroborate, hexafluorophosphate, tetra(perfluorophenyl)borate, hydride, oxide, peroxide, hydroxide, nitride, arsenate, arsenite, perchlorate, carbonate, bicarbonate, chromate, dichromate, iodate, bromate, chlorate, chlorite, hypochlorite, hypobromite, cyanide, cyanate, isocyanate, fulminate, thiocyanate, isothiocyanate, azide-based, tetracarbonylcobaltate, carbamoyldicyanomethanide, dicyanonitrosomethanide, dicyanamide, tricyanomethanate, amide, and permanganate.The lead salt solution may further contain a lead(II) salt or a lead(IV) salt in a molar ratio of 0 to 100% with respect 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, Zr as the salt of the aforementioned anion.

[0089] In certain embodiments, one or more ionic liquids may be added to lead halide prior to the addition of any other optional additives (e.g., solvents). Next, a solvent may be added to the vessel to dissolve the lead halide solid, forming a lead halide solution. In other embodiments, one or more ionic liquids may be added to the lead halide solution after the addition of the solvent, or may be added simultaneously with the solvent, or may first be mixed with the solvent before being introduced to the lead halide. 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 between about 20°C and about 150°C. In one embodiment, the lead halide solid is dissolved at about 85°C. The lead halide solid may be dissolved for a sufficiently long time to form a solution, which may be carried out over up to about 72 hours. The resulting solution forms the basis of the lead halide precursor ink. In certain embodiments, the lead halide precursor ink may have a lead halide concentration between about 0.001 M and about 10 M. In certain embodiments, the lead halide solution has a lead halide concentration of about 1 M. In certain embodiments, the lead halide solution may further include an amino acid (e.g., 5-aminovaleric acid, histidine, glycine, lysine), an amino acid hydrogen halide salt (e.g., 5-aminovaleric acid hydrochloride), an IFL surface modification (SAM) agent (such as those discussed previously in this application), or combinations thereof.

[0090] Next, a Group 1 metal halide solution is formed. An amount of a Group 1 metal halide may be collected in a clean, dry container under 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, and potassium fluoride. The Group 1 metal halide may comprise a single type of Group 1 metal halide or may comprise a mixture of Group 1 metal halides in exact ratios. In one embodiment, the Group 1 metal halide may have cesium iodide. In another embodiment, the Group 1 metal halide can include rubidium iodide. In another embodiment, the Group 1 metal halide may include sodium iodide. In another embodiment, the Group 1 metal halide may include potassium iodide. In an embodiment, the Group 1 metal halide may be mixed with lead halide in a clean, dry container prior to the addition of other additives (e.g., ionic liquids or solvents). In an embodiment, the Group 1 metal halide and lead halide may be weighed and added in a specific order. In an embodiment, the lead halide may be weighed and added to the container prior to the addition of any Group 1 metal halide.

[0091] Alternatively, other Group 1 metal salt precursors may be used with or instead of the Group 1 metal halide salts to form a Group 1 metal salt solution. Suitable Group 1 precursor metal salts may include any combination of a Group 1 metal and the following anions: nitrate, nitrite, carboxylate, acetate, formate, oxalate, sulfate, sulfite, thiosulfate, phosphate, tetrafluoroborate, hexafluorophosphate, tetra(perfluorophenyl)borate, hydride, oxide, peroxide, hydroxide, nitride, arsenate, arsenite, perchlorate, carbonate, bicarbonate, chromate, dichromate, iodate, bromate, chlorate, chlorite, hypochlorite, hypobromite, cyanide, cyanate, isocyanate, fulminate, thiocyanate, isothiocyanate, azide, tetracarbonylcobaltate, carbamoyldicyanomethanide, dicyanonitrosomethanide, dicyanamide, tricyanomethanate, amide, and permanganate.

[0092] Next, a solvent may be added to the container to dissolve the Group 1 metal halide solid and 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 to the Group 1 metal halide solution after the addition of the solvent. In another embodiment, one or more ionic liquids may be added simultaneously with the solvent or first added to the solvent before introducing the solvent 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 between about 20 °C and 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 a sufficiently long time to form a solution, which may be carried out over up to about 72 hours. The resulting solution forms a Group 1 metal halide solution. In certain embodiments, the Group 1 metal halide solution may have a Group 1 metal halide concentration between about 0.001 M and about 10 M. In certain embodiments, the Group 1 metal halide solution has a Group 1 metal halide concentration of about 1 M. In certain embodiments, the Group 1 metal halide solution may further have an amino acid (e.g., 5-aminovaleric acid, histidine, glycine, lysine), an amino acid hydrohalide salt (e.g., 5-aminovalerate hydrochloride), an IFL surface modification (SAM) agent (such as those previously discussed in this application), or combinations thereof.

[0093] Next, a lead halide solution and a 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 the Group 1 metal halide between 0% and 25% of the molar concentration of the lead halide. In certain embodiments, the lead halide precursor ink may have a molar concentration of the Group 1 metal halide that is 1% of the molar concentration of the lead halide. In certain embodiments, the lead halide precursor ink may have a molar concentration of the Group 1 metal halide that is 5% of the molar concentration of the lead halide. In certain embodiments, the lead halide precursor ink may have a molar concentration of the Group 1 metal halide that is 10% of the molar concentration of the lead halide. In certain embodiments, the lead halide precursor ink may have a molar concentration of the Group 1 metal halide that is 15% of the molar concentration of the lead halide. In certain embodiments, the lead halide precursor ink may have a molar concentration of the Group 1 metal halide that is 20% of the molar concentration of the lead halide. In certain embodiments, the lead halide precursor ink may have a molar concentration of the Group 1 metal halide that is 25% of the molar concentration of the lead halide. In certain embodiments, the lead halide solution, the Group 1 metal halide solution, and / or 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 (along with one or more solvents) to a single solution to form the lead halide precursor ink.

[0094] Next, the lead halide precursor ink containing the ionic liquid may be deposited on a desired substrate. Suitable substrate layers may include any of the substrate layers previously described in this disclosure. As previously mentioned, the lead halide precursor ink may be deposited by various means including, but not limited to, drop casting, spin casting, gravure coating, blade coating, reverse gravure coating, slot die printing, screen printing, or inkjet printing. In certain embodiments, the lead halide precursor ink may be spin-coated onto the substrate at a speed of from about 500 rpm to about 10,000 rpm for a time of from about 5 seconds to about 600 seconds. In one embodiment, the lead halide precursor ink may be spin-coated onto the substrate in a two-step program. In certain embodiments, an anti-solvent may be added to the substrate during one or more steps. For example, in one embodiment, the thin film precursor ink may be spin-coated at 1000 rpm and 4000 rpm for about 12 seconds and 25 seconds, respectively, and a chlorobenzene anti-solvent may be added during the second step. The thin film precursor ink may be deposited on the substrate in an ambient atmosphere within a humidity range of from about 0% relative humidity to about 50% relative humidity, from about 0.01% relative humidity to about 50% relative humidity, from about 0.1% relative humidity to about 50% relative humidity, or from 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%. Next, the lead halide precursor ink is dried in an atmosphere substantially free of water, i.e., a relative humidity of less than 30% or 7 g H2O / m 3 and less to form a thin film.

[0095] Next, the lead halide precursor ink may be thermally annealed at a temperature from about 20 °C to about 300 °C for up to about 24 hours. In one embodiment, the thin film may be thermally annealed at a temperature of about 100 °C for about 30 minutes. Next, a conversion process may be used to complete the perovskite material active layer by immersing or rinsing the precursor film in a salt solution containing a solvent or mixture of solvents (e.g., DMF, isopropyl alcohol, methanol, ethanol, butanol, chloroform, chlorobenzene, dimethyl sulfoxide, water), and a salt (e.g., methylammonium iodide, formamidinium iodide, guanidinium iodide, 1,2,2-triaminovinylammonium iodide, 5-aminovaleric acid hydroiodide) at a concentration from 0.001 M to 10 M. In certain embodiments, the perovskite material thin film may be thermally post-annealed in the same manner as the first line of this paragraph.

[0096] Figures 7 through 11 show scans of current-voltage and current density-voltage, and related test data, of a photovoltaic device incorporating a perovskite material formed using an ionic liquid of the present disclosure. The devices used to generate the scans in Figures 7 through 11 were constructed using the methods described below.

[0097] In this example, first, the FTO substrate is cleaned with detergent, deionized water, acetone, and isopropanol by ultrasonic waves, and then treated with a UV / ozone cleaner for 15 minutes. A TiO2 dense layer (cp-TiO2) was deposited on the FTO by spray pyrolysis using a titanium diisopropoxide bis(acetylacetonate) solution diluted with 2-propanol at a volume ratio of 500 °C and 1:18 and annealed in-situ for 30 minutes. Next, a mesoporous TiO2 (mpTiO2) solution containing 1 g of TiO2 paste diluted with 10 mL of absolute ethanol solution was deposited on the cpTiO2 / FTO substrate by a one-step spin-coating process at 4,500 rpm for 20 seconds. After annealing at 125 °C for 30 minutes, the formed TiO2 film was gradually heated to 500 °C in air and then calcined for 20 minutes. Next, an SnO2 layer was deposited on the substrate by spin-coating a 0.1 M aqueous SnCl4 solution in a one-step process at 3,000 rpm for 20 seconds. Then, the substrate was transferred to a hot plate and held at a temperature between 150 °C and 190 °C for 1 hour. Next, the substrate was treated with UV / ozone for 30 minutes.

[0098] Next, a lead halide precursor solution (with or without an ionic liquid) was prepared by dissolving PbI2 (1.35 M), RbI (0.05 M), CsI (0.05 M), FAI (1.15 M), and MACl (0.10 M) in a mixed solvent of DMF:DMSO with a volume ratio of 3:1. In this example, all the solids were weighed and added in the order of PbI2, RbI, CsI, FAI, and MACl. Next, DMF was added, and then DMSO was added. In other embodiments, DMSO may be added before DMF.

[0099] For comparison, the device of FIG. 14 was formed without using an ionic liquid. For the remaining elements, the ionic liquid of the present disclosure was added to the lead halide precursor solution in an amount of 0.5 mol %. When forming the perovskite materials of the devices of FIGS. 3, 5, and 6, an ionic liquid represented by Formula 8 was used as the cation together with the anions of chloride, TFSI, and tetraphenylborate, respectively. When forming the perovskite materials of the devices of FIGS. 4 and 7, an ionic liquid represented by Formula 9 was used as the cation together with the anions of TFSI and chloride, respectively. Next, 25 μL of each lead halide precursor solution was spin-coated onto an FTO / dense layer TiO2 / mesoporous layer TiO2 / SnO2 substrate using a two-step program carried out 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 onto the substrate. Next, the spin-coated film was annealed at 100° C. for 30 minutes and cooled to room temperature. Next, a solution of PEAI diluted with IPA (10 mg / 1 mL) was spin-coated onto the substrate at 4,000 rpm for 15 seconds. After the PEAI layer was formed, 45 μL of the spiro-OMeTAD solution was deposited onto the perovskite layer by spin-coating at 4,000 rpm for 12 seconds. The spiro-OMeTAD solution was prepared by dissolving spiro-OMeTAD:FK209:Li-TFSI:TBP in a molar ratio of 1:0.03:0.5:3.3.2 in chlorobenzene using 4-tert-butylpyridine (“TBP”), Li-TFSI in acetonitrile, and Co[t-BuPyPz]3[TFSI]3 (“FK209”) in acetonitrile. Finally, a 70 nm gold contact layer was thermally evaporated as the counter electrode, completing the device fabrication.

[0100] Next, solar cell measurements were performed at room temperature to generate the current-voltage characteristics and other data of the perovskite solar cells as shown in FIGS. 46 to 51 and FIG. 57. The active area of the solar cell was 0.09 cm 2Masked with a metal opening to suppress the influence of scattered light. Table 6 below shows the 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.

[0101]

Table 6

[0102] Figures 9 to 11 show images from a scanning electron microscope comparing perovskite PVs manufactured using various ionic liquids with perovskite PVs manufactured without using ionic liquids.

[0103] Many modifications, changes, and corrections to the described embodiments are possible without departing from the scope of the invention as defined in the claims. The present invention is not limited to the described embodiments, but is intended to include the full scope defined by the language of the claims and their equivalents.

Claims

1. Forming a perovskite precursor ink comprising lead halide, ionic liquid, solvent, and formamidinium halide; Depositing the perovskite precursor ink onto a substrate; Drying the perovskite precursor ink to form a perovskite precursor film; Annealing the perovskite precursor film; A method having the above steps.

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

3. The method according to claim 1, wherein the ionic liquid contains an organic cation.

4. The ionic liquid contains an anion selected from the group consisting of halides, bis(trifluoromethane)sulfonimide (TFSI), and borate anions of the general formula [BR 1 R 2 R 3 R 4 , where each of R － to R 1 to R 4 is selected from the group consisting of F, 【Chemical Formula 1】 derivatives thereof, and any combination thereof, according to claim 1.

5. The method according to claim 1, wherein the lead halide contains lead(II) iodide.

6. The method according to claim 1, wherein the perovskite precursor ink is deposited onto the substrate by spin coating.

7. The method according to claim 1, wherein the perovskite precursor film is annealed at 100 °C for 30 minutes.

8. The method according to claim 1, wherein the perovskite precursor ink contains the ionic liquid in an amount of about 0.01 to about 10 mol% based on the lead atoms in the perovskite precursor ink.

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

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

11. The perovskite material according to claim 9, wherein the ionic liquid contains an organic cation.

12. The ionic liquid contains an anion selected from the group consisting of halides, bis(trifluoromethane)sulfonimide (TFSI), and borate anions of the general formula [BR 1 R 2 R 3 R 4 , where each of R － to R 1 to R 4 is selected from the group consisting of F, 【Chemical Formula 2】 their derivatives, and any combination thereof. The perovskite material according to claim 9.

13. The perovskite material according to claim 9, wherein the lead halide contains lead(II) iodide.

14. The perovskite precursor ink is deposited on the substrate by spin coating, and the perovskite material according to claim 9.

15. The perovskite precursor film is annealed at 100 ° C for 30 minutes, and the perovskite material according to claim 9.

16. The perovskite precursor ink contains the ionic liquid in an amount of about 0.01 to about 10 mol% based on the lead atoms in the perovskite precursor ink, and the perovskite material according to claim 9.

17. A step of forming a lead halide precursor ink containing a Group 1 metal halide, lead halide, ionic liquid and solvent; A step of depositing the lead halide precursor ink on a substrate; A step of drying the lead halide precursor ink to form a lead halide film; A step of annealing the lead halide film; And a method.

18. The ionic liquid is ammonium, formamidinium, guanidinium, ethenetetramine cation, imidazolium cation, a compound of the general formula [R 3 R 2 R 1 PNPR 4 R 5 R 6 , ＋ a cation having a general formula [R 3 R 2 R 1 PNPR 4 R 5 R 6 , ＋ and a cation selected from the group consisting of cations and any combinations thereof, where R 1 to R 6Each of them is independently selected from the group consisting of hydrogen, methyl group, ethyl group, propyl group, butyl group, pentyl group, 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, amino acid, silicon-containing group, alkoxy group, halide, pseudohalide, and any combination thereof, according to the method of claim 17.

19. The ionic liquid has a general formula of 【Chemical Formula 3】 and has a cation of, according to the method of claim 17.

20. The ionic liquid has a general formula of 【Chemical Formula 4】 and has a cation of, according to the method of claim 17.

Images