Perovskite precursor solution with excellent solution stability and method for manufacturing same

Abstract

Disclosed are a perovskite precursor solution with excellent solution stability and a method for manufacturing same. A perovskite precursor solution according to the present invention comprises: perovskite particles represented by chemical formula 1; and reductive anions, wherein the perovskite precursor solution contains 5-25 mol% of the reductive anions per 100 mol% of the perovskite particles. [Chemical formula 1] AMX3, where A is a formamidinium cation (HC(NH2)2)+), M is a divalent metal cation, and X is a halide.

Description

Perovskite precursor solution with excellent solution stability and method for preparing the same

[0001] The present invention relates to a perovskite precursor solution with improved solution stability and a method for preparing the same.

[0002] The rapid expansion of research in the field of perovskite solar cells (PSCs) is primarily due to the relatively inexpensive solution processing and the excellent optoelectronic properties of perovskite films.

[0003] Perovskites have an adjustable band gap, a high absorption coefficient, a low carrier recombination rate, and high carrier mobility.

[0004] Due to these optoelectronic properties, perovskites are attracting attention for their potential to be commercialized as next-generation photovoltaic materials.

[0005] Recently, research on continuous perovskite compositions has continued from MAPbI3 (methylammonium lead triiodide) to FAPbI3 (formamidinium lead triiodide).

[0006] Compared to MAPbI3, FAPbI3 is thermally more stable and has a bandgap closer to the Shockley-Queisser limit, making FAPbI3 potentially the most promising perovskite material for single-junction PSCs. Unfortunately, thin FAPbI3 films undergo a phase transition from a black α-phase to a photoinert δ-phase at temperatures below 150°C. To address this problem, solutions such as mixing FAPbI3 with a combination of MA+, Cs+, and Br- ions are being studied.

[0007] However, since perovskites have low solution stability and a very short shelf life, there is a need to develop perovskite precursor solutions to ensure long-term storage stability.

[0008] The objective of the present invention is to provide a perovskite precursor solution with excellent long-term storage stability and a method for preparing the same.

[0009] The objects of the present invention are not limited to those mentioned above, and other unmentioned objects and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims.

[0010] The perovskite precursor solution according to the present invention comprises perovskite particles represented by Chemical Formula 1; and reducing anions; and is characterized by comprising 5 to 25 mol% of reducing anions relative to 100 mol% of the perovskite particles.

[0011] [Chemical Formula 1]

[0012] AMX3

[0013] A is the formamidinium cation (HC(NH2)2) + ) and M is a divalent metal cation, and X is a halide.

[0014] The above reducing anion is formate (HCOO - It may include one or more of ) and oxalate.

[0015] With respect to 100 mol% of the above perovskite particles, CsI 1 to 20 mol% and PbI 27.5 to 20 mol% may be further included.

[0016] With respect to 100 mol% of the above perovskite particles, CsPbBr30 to 5 mol% may be further included. The above perovskite precursor solution contains M = Pb2 + It may include, and the above X is I - It may include.

[0017] The above perovskite precursor solution may include an α-phase.

[0018]

[0019] A method for preparing a perovskite precursor solution according to the present invention comprises the step of mixing perovskite particles represented by Chemical Formula 1 with a reducing anion, and is characterized by mixing 5 to 25 mol% of the reducing anion with respect to 100 mol% of the perovskite particles.

[0020] [Chemical Formula 1]

[0021] AMX3

[0022] A is the formamidinium cation (HC(NH2)2) + ) and M is a divalent metal cation, and X is a halide.

[0023] The above reducing anion is formate (HCOO - It may include one or more of ) and oxalate.

[0024] The above reducing anion may include FAHCOO, which is formed by the reaction of formamidine (FA) acetic acid and formic acid.

[0025] The perovskite precursor solution according to the present invention includes a solution stabilizer such as a formate anion, thereby having excellent long-term storage stability and the effect of maintaining said storage stability for more than one year.

[0026] In addition, the film and photovoltaic device formed from the perovskite precursor solution with excellent stability according to the present invention can exhibit excellent power conversion efficiency (PCE) and film stability.

[0027] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below.

[0028] Figure 1 is a photograph showing the storage stability of a FAHCOO-based precursor solution according to the present invention.

[0029] Figure 2 is a photograph showing the storage stability of the FAHCOO-based precursor solution after a period of time under the conditions of Figure 1.

[0030] Figure 3 is a photograph showing the reducing properties of a FAHCOO-based precursor solution according to the present invention.

[0031] Figure 4 is a photograph showing the storage stability of a FAHCOO-based precursor solution according to the present invention after 4 months.

[0032] Figure 5 is a graph for Figure 4.

[0033] Figure 6 is a photograph showing the storage stability of the FAHCOO-based precursor solution after a period of time under the conditions of Figure 4.

[0034] Figure 7 is a graph for Figure 6.

[0035] Figure 8 is a graph of current density according to voltage for a comparative example specimen and a FAHCOO-based precursor solution specimen of the present invention.

[0036] Figure 9 is a graph of current density according to voltage of a specimen formed into a film of the FAHCOO-based precursor solution of the present invention.

[0037] Figure 10 is a photograph showing the storage stability of FAOx (FA COOCOOH) and FA2Ox (FA(COO)2) based precursor solutions according to the present invention.

[0038] Figure 11 is a photograph showing the change in a precursor solution with Ref and FAHCOO 0 to 40 mol% added under harsh conditions at 85°C.

[0039] Figure 12 is a graph showing the change of the precursor solution in Figure 11.

[0040] Figure 13 is a photograph showing the change in the precursor solution with Ref and FA2Ox added under harsh conditions of 85°C.

[0041] The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0042] In the following, the statement that any configuration is placed on the "upper (or lower)" of a component or on the "upper (or lower)" of a component may mean not only that any configuration is placed in contact with the upper (or lower) surface of said component, but also that another configuration may be interposed between said component and any configuration placed on (or below) said component.

[0043] In addition, where it is stated that one component is "connected," "combined," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "combined," or "connected" through another component.

[0044] Hereinafter, a perovskite precursor solution and a method for preparing the same according to some embodiments of the present invention will be described.

[0045] The chemical mechanism for the damage process of perovskite solutions is as follows.

[0046] [Equation 1]

[0047]

[0048] Equation 1 shows the reduction potentials of iodine and O2, where a positive reduction potential indicates a spontaneous forward reaction, and a negative reduction potential indicates a spontaneous reverse reaction.

[0049] [Equation 2]

[0050]

[0051] Equation 2 shows the oxidation of iodide due to acidic conditions, O2.

[0052] The FAPbI3 precursor solution is FA + It exhibits weak acidity due to (formamidine), and over time I - When it reacts with oxygen, it is oxidized, and the solution turns red (formation of I2).

[0053] MACl (Methylammonium chloride) used as an additive is FA + As an acid stronger than (formamidine) - It promotes the oxidation of, making the solution more unstable. If strong acids such as HCl or HI are added to the solution, I - The oxidation of is accelerated even more. - The oxidation rate of is also affected by the solvent, and there is a phenomenon where it is accelerated more in DMSO than in DMF.

[0054] The oxidation-reduction reaction for preventing damage to the perovskite solution is as follows.

[0055] [Equation 3]

[0056]

[0057] In Equation 3, the reduction of CO2 makes the reverse reaction a spontaneous reaction.

[0058] [Equation 4]

[0059]

[0060] In Equation 4, the addition of formic acid inhibits the oxidation of I2.

[0061] HCOOH reduces I2 back to I - It can serve as a reducing agent that reduces it.

[0062] In formic acid, aldehyde (strong reducing functional group) and carboxylic acid functional group coexist.

[0063] [Equation 5]

[0064]

[0065] I - Combining the oxidation reaction of and the reduction reaction of I2, the individual reactions are expressed as Equation 5 above. It can be confirmed that HCOOH reacts with oxygen to oxidize and form CO2, while oxygen forms water. At this time, I - It can be seen that it is not damaged as long as formic acid is present, and until HCOOH is completely reacted, I - It can be expected that it will remain stable.

[0066] However, since HCOOH will be depleted in the solution over time, the conditions must be readjusted to a state where the above reaction can be inhibited.

[0067] The acid-base reaction for preventing damage to perovskite solutions is as follows.

[0068] [Equation 6]

[0069]

[0070] Formic acid is Bronsted-Lowry acid (also known as Arrhenius acid) H + Can produce.

[0071] Looking at the reduction reaction of oxygen, H + It can be seen that the concentration of also participates in the reaction. H +Since the equilibrium reaction shifts toward the forward reaction as the concentration increases, it can be predicted that the reduction of oxygen is promoted as the acidity increases. The addition of simple HCOOH is I - It cannot completely inhibit the oxidation of [the substance]. If an excessive amount of formic acid is added, it may be difficult to ensure the long-term stability of the solution due to the promotion of oxidation-reduction reactions and the depletion of HCOOH.

[0072] [Equation 7]

[0073]

[0074] The conjugate base of formic acid is HCOO - As, this can act as a base, and H + It can inhibit the reduction reaction of oxygen by reducing the concentration of HCOO - It also has reducing properties, so I - It is possible to inhibit the oxidation of . HCOO in the perovskite precursor solution. - If exists, I - It is possible to inhibit the oxidation of.

[0075] These reducing anions are formate (HCOO - It may be a conjugate base of an organic acid including ), oxalate, citrate, etc., and specifically, formate anion (FAHCOO - ), trimethylammonium formate (C4H 11 NO2)), triethylammonium formate (C7H 17 It may include NO2), tertiary ammonium formate, FAOx (FA COOCOOH, FA bioxalte or Hydrogen oxalte, carboxy formate), FA2Ox (FA (COO)2, FA oxalate), etc.

[0076] The side reactions of the formate anion FAHCOO (FA: formamidine) are as follows.

[0077] FAHCOO is also known as Formamidinium formate (Formamidine Formic acid salt).

[0078] [Equation 8]

[0079]

[0080] Formic acid, a type of carboxylic acid, can react with amines to form amides. For example, if FAHCOO and MACl are used in combination, FA + + HCOO - + CH3NH3 + + Cl - am.

[0081] This is a condition similar to that of adding an acid catalyst to HCOOH and CH3NH2.

[0082] A condensation reaction proceeds to form a solvent of N-methylformamide. Under similar conditions, using a mixture of DMACl (Dimethylammonium chloride) and FAHCOO results in the formation of DMF (N,N-Dimethylformamide). Although the condensation reaction is slow, the mixed use of FAHCOO with 0th, 1st, and 2nd ammonium compounds does not ensure long-term stability of the solution. Furthermore, it presents disadvantages in the formation of intermediate phases, which actually hinders the smooth formation of perovskites.

[0083] In the present invention, phase formation can be induced by using a FAHCOO (FA: formamidine) additive.

[0084] In the case of MACl, which is currently used as an additive, OFm(HCOO- It is difficult to use because it undergoes a condensation reaction with ). Similarly, MAPbBr3, which is used for bandgap tuning, is also difficult to add. Although phase formation is possible using only FAHCOO as an additive, strong effects like those of MACl may not appear.

[0085] CsI(Cs + When ) is present, it has the effect of inducing alpha phase formation, similar to MACl. However, if only CsI is added, CsI acts as an impurity and causes a sharp decrease in efficiency; therefore, if PbI2 is added to induce the formation of CsPbI3, a smooth phase can be formed.

[0086] For FAPbI3 100 mol%, adding 1 to 20 mol% of CsI forms a clean phase, and adding 7.5 to 17.5 mol% of PbI2 has an advantageous effect in terms of alpha phase formation and stability because the content of PbI2 is greater than the content of CsI.

[0087] Accordingly, in the present invention, a precursor solution based on FAHCOO additive, which is a formate anion, was prepared.

[0088] The perovskite precursor solution according to the present invention is MA + A perovskite precursor solution that does not contain (Methylammonium) comprises perovskite particles represented by Chemical Formula 1 and reducing anions, and is characterized by comprising 5 to 25 mol% of reducing anions relative to 100 mol% of the perovskite particles.

[0089] [Chemical Formula 1]

[0090] AMX3

[0091] A is the formamidinium cation (HC(NH2)2) + ) and M is a divalent metal cation, and X is a halide.

[0092] The reducing anion can form a hydrogen bond with the formamidinium cation of the perovskite crystal particle.

[0093] M is Pb 2+ , Sn 2+ , Pd 2+ , Cu 2+ , Ge 2+ , Sr 2+ , Cd 2+ , Ca 2+ , Ni 2+ , Mn 2+ , Fe 2+ , Co 2+ , Sn 2+ , Yb 2+ or Eu 2+ It could be.

[0094] Preferably, M is Pb2 + It may include.

[0095] X may be one or more selected from F-, Cl-, Br-, and I-, and preferably I - It may include.

[0096] The average particle size of the perovskite particles may be 0.1 to 2 μm, but is not limited thereto.

[0097] In addition, the perovskite precursor solution may contain 5 to 25 mol% of reducing anions relative to 100 mol% of perovskite particles, preferably 5 to 20 mol%, 8 to 15 mol%, and more preferably 9 to 10 mol%.

[0098] When the reducing anion content is less than 5 mol%, the manufacturing efficiency is low and the likelihood of ensuring solution stability is low.

[0099] By including 5 to 25 mol% of reducing anions in the perovskite precursor solution, stable phase formation is possible, and long-term storage stability is improved. In particular, the stability of the perovskite precursor solution can be maintained for more than one year, and the device using it also has excellent stability.

[0100] The perovskite precursor solution may further contain 1 to 20 mol% of CsI and 7.5 to 20 mol% of PbI with respect to 100 mol% of perovskite particles, and preferably may further contain 15 to 20 mol% of CsI and 15 to 20 mol% of PbI.

[0101] When CsI and PbI2 react, CSPbI3 is formed, and CSPbI3 is present in the solution.

[0102] The molar ratio of perovskite particles to CSPbI3 can be 1:0.1 to 0.5, and preferably 1:0.1 to 0.3.

[0103] In addition, for 100 mol% of perovskite particles, CsPbBr30 may be further included in an amount of 5 mol%, and preferably 2 to 4 mol% may be further included.

[0104] With this composition ratio, the perovskite precursor solution may contain an α-phase and may emit fluorescence upon ultraviolet (UV) irradiation.

[0105] A method for preparing a perovskite precursor solution according to the present invention comprises the step of mixing perovskite particles represented by Chemical Formula 1 with a reducing anion, and is characterized by mixing 5 to 25 mol% of the reducing anion with respect to 100 mol% of the perovskite particles.

[0106] [Chemical Formula 1]

[0107] AMX3

[0108] A is the formamidinium cation (HC(NH2)2)+ ) and M is a divalent metal cation, and X is a halide.

[0109] At this time, the reducing anion can be formed by the reaction of formamidine acetic acid (FA) and formic acid.

[0110] Details regarding perovskite particles and reducing anions are the same as those described above in the precursor solution, so they will be omitted.

[0111] A film can be manufactured by performing the step of forming a photoactive layer (or light absorption layer) by applying a precursor solution containing perovskite particles onto a substrate. After the step of forming the photoactive layer, the steps of heat-treating the photoactive layer and applying an isopropanol solution containing octyl ammonium iodide onto the heat-treated photoactive layer may be performed, but are not limited thereto.

[0112] The manufactured film may include a cured product of the aforementioned perovskite precursor solution. Additionally, the film may be a photoactive film.

[0113] The photoelectric device according to the present invention is characterized by comprising a cured product of the aforementioned perovskite precursor solution.

[0114] The above photovoltaic device may be a solar cell.

[0115] The solar cell structure containing perovskite is as follows.

[0116] The electron transport layer is located between the transparent conductive oxide (TCO) substrate and the perovskite layer.

[0117] The electron transport layer transports electrons excited in the perovskite light absorption layer to the transparent conductive glass substrate and prevents recombination by blocking the penetration of holes. Materials commonly used in the electron transport layer are inorganic metal oxides such as TiO2 and SnO2. For efficient electron injection and transport, characteristics such as high electron mobility, as well as compatibility of the band structure with the light absorption layer, are required.

[0118] The light absorbing layer contains a perovskite structure.

[0119] Perovskites are suitable for fabricating solar cells because they possess low binding energy, long carrier transport distances, and a broad light absorption band. Additionally, depending on the chemical composition of the material, the band gap ranges from 1.1 to 2.3 eV, and the easily adjustable band gap is one of the greatest advantages of perovskite solar cells. The photoelectric effect at a desired wavelength can be achieved through band gap tuning.

[0120] The hole transport layer not only improves the performance of the solar cell by transporting holes generated in the perovskite to the counter electrode, but also enhances long-term operational stability by protecting the perovskite layer from external factors such as humidity. To date, the most commonly used hole transport layers in perovskite solar cells are materials called Spiro-OMeTAD and PTAA.

[0121] The single molecule Spiro-OMeTAD has been continuously adopted in dye-sensitized solar cells, where it was utilized as a solid electrolyte and applied as a hole transport layer, preventing degradation by iodine. Such organic-based materials are widely used in perovskite solar cells because they are soluble in non-polar solvents that do not damage the perovskite layer and do not require heat treatment.

[0122] PTAA, a polymer, possesses higher hole mobility than other polymers due to its inherent characteristic of having many holes. PTAA has multiple benzene rings, and its pi (π) conjugated structure forms the channels necessary for hole transport. It enables appropriate energy level matching with perovskite, resulting in excellent hole extraction and electron backflow prevention capabilities.

[0123] Solar cells are semiconductor devices that generate electricity by absorbing light. Performance parameters such as short-circuit current (Isc), open-circuit voltage (Voc), fill factor (FF), and power conversion efficiency (PCE) are key factors that determine the performance and market value of solar cells.

[0124] Performance measurement is conducted through characteristic evaluation in accordance with standards set by the International Electrotechnical Commission (IEC).

[0125] Under the specified solar cell performance evaluation conditions, the spectrum of light irradiated onto the solar cell is the AM 1.5G reference spectrum, the temperature during measurement is 25℃, and the light irradiation intensity is 100mW / cm² 2 am.

[0126] In order to irradiate light in the same way as the characteristic evaluation of commonly used solar cells, virtual sunlight is irradiated through a solar simulator, and the output values ​​from both ends of the solar cell are measured using the irradiated light.

[0127] The IV curve and efficiency of the perovskite solar cell device were measured using the Newport Model 94083A solar simulator, and the light source used was AM 1.5G (100 mA / cm²). 2 A Keithley 2460 Instruments voltage source meter with a built-in ) was used.

[0128] As such, specific examples regarding the perovskite precursor solution and its preparation method are as follows.

[0129] Figure 1 is a photograph showing the storage stability of a FAHCOO-based precursor solution according to the present invention.

[0130] For the example specimen, a precursor solution was prepared by mixing FAPbI3640 mg (100 mol%) with CsI 66 mg (20 mol%), PbI2117 mg (20 mol%), FAHCOO 23 mg (25 mol%), CsPbBr30 ~ 5 mol%, and DMF and DMSO as solvents in an 8:2 ratio.

[0131] The specimen of the above example is indicated as FA Formate in the following drawing.

[0132] In the drawings below, Ref (MACl) is the result of adding MACl instead of FA Formate to the above precursor solution.

[0133] Only FAPbI3 is a mixture of only FAPbI3 and an organic solvent.

[0134] Ref(fresh) is Ref(MACl) obtained by adding MACl to FA Formate, observed on the day of manufacture.

[0135] The photograph from June 21, 2023 showed a bright yellow color immediately after the solution was prepared.

[0136] In the photo from June 21, 23, the efficiency of the Ref (MACl) solution began to decline rapidly after more than one week, and a red color began to appear after about 15 days to a month. To compare the effects of the additive, a solution composed only of FAPbI3 was added.

[0137] In the photo from July 6, 23, after about two weeks, the solution composed solely of FAPbI3 also began to change color, and the Ref (MACl) solution became even redder. FA Formate with added FAHCOO maintained a bright yellow color, just like Ref (fresh).

[0138] Figure 2 is a photograph showing the storage stability of the FAHCOO-based precursor solution after a period of time under the conditions of Figure 1.

[0139] It was confirmed that the color of the solution did not change and remained stable even after more than one year had passed.

[0140] Figure 3 is a photograph showing the reducing properties of a FAHCOO-based precursor solution according to the present invention.

[0141] I210mol% Addition (Left): I210mol% was added to the FA Formate, which is the specimen of the above example.

[0142] I2 Added X (Right): This is FA Formate, the specimen of the above example.

[0143] As in the addition of 10 mol% of I2 (left), I2 was intentionally added to prepare the solution.

[0144] Over time, the color of I2 disappears and is reduced to a bright yellow.

[0145] HCOOH + I2 → 2HI + CO2

[0146] As the above reaction proceeds, the solution is I - It becomes a solution with a rich composition, which is advantageous for forming alpha-phase perovskites.

[0147] Figure 4 is a photograph showing the storage stability of a FAHCOO-based precursor solution according to the present invention after 4 months, and Figure 5 is a graph of Figure 4.

[0148] Short-circuit current refers to the current flowing through a solar cell when the voltage applied to the solar cell is zero. It is the current flowing when the circuit is short-circuited, and it is the current output when sunlight is received in the absence of external resistance; it is equal to the maximum current that the solar cell can generate.

[0149] Generally, to exclude the influence of the actual effective area of ​​the solar cell, the short circuit current density (Jsc), calculated by dividing the short circuit current by the area, was used.

[0150] Open-circuit voltage (Voc) is the maximum voltage obtainable from a solar cell, and this occurs when the current is zero. Open-circuit voltage refers to the photovoltaic voltage generated when the circuit is open or when an infinite resistance is connected so that no current flows.

[0151] The fill factor (FF) is a measure of how closely the IV curve approaches the rectangle formed by the X and Y axes, the open-circuit voltage, and the short-circuit current, and the fill factor is the ratio of the maximum output of the solar cell to the product of the short-circuit current and the open-circuit voltage.

[0152] 1. Fresh MACl observed after 4 months is 4. Aging Form.

[0153] 2. Fresh form observed 4 months later is 4. Aging form.

[0154] [Table 1]

[0155]

[0156] The Ref solution showed a rapid decrease in efficiency during device manufacturing after about 4 months. The Target (FAHCOO) 4. Aging Form showed a result of 18.28%, which is similar to the initial efficiency of 18.55%, even after 4 months. The composition of the stable solution manufactured at that time was FAPbI3 + FAHCOO + HCOOH, which showed somewhat lower efficiency.

[0157] Figure 6 is a photograph showing the storage stability of the FAHCOO-based precursor solution after a period of time under the conditions of Figure 4, and Figure 7 is a graph of Figure 6.

[0158] [Table 2]

[0159]

[0160] Ref(Fresh MACl) was not fabricated into a device because the coating film itself was not formed. It was confirmed that the efficiency of the Target solution remained unchanged at 18.55% even after more than 9 months had passed. Through this experiment, it was confirmed that the long-term stability of the precursor solution of the present invention has been secured.

[0161] Figure 8 is a graph of current density according to voltage for a comparative example specimen and a FAHCOO-based precursor solution specimen of the present invention.

[0162] The solar cell has a stacked structure of Glass / ITO / SnO2 / PVSK / ST / Spiro-OMETAD / Au.

[0163] The PVSK solution composition (Target) is a mixture of FAPbI3:CsPbI3 (1:0.15), CsPbBr3 2 mol%, and FAHCOO 10 mol%.

[0164] 1. MACl is the above composition in which MACl is added instead of FAHCOO.

[0165] [Table 3]

[0166]

[0167] The PVSK solution composition (Target) is expected to show an efficiency of about 24% in ITO.

[0168] Figure 9 is a graph of current density according to voltage of a specimen formed into a film of the FAHCOO-based precursor solution of the present invention.

[0169] The solar cell has a stacked structure of Glass / ITO / SnO2 / PVSK / ST / Spiro-OMETAD / Au.

[0170] The PVSK solution composition (Target) is a mixture of FAPbI3100mol%, CsPbI315mol%, CsI2.5mol%, CsPbBr32mol%, and FAHCOO25mol%.

[0171] [Table 4]

[0172]

[0173] As a result of measuring with an AR film (Anti-reflection film) attached to the Target sample in Table 3, Voc improvement was slightly needed.

[0174] Therefore, HCOO - By utilizing the basic properties and reducing power of to raise the pH, H + Lowering the concentration of (acid catalytic effect) and I - It was confirmed that it inhibits the oxidation of.

[0175] When using a mixture of alkylammnium materials such as MA, side reactions occur, making it difficult to use additives such as MACl and MAPbBr3. Instead, improvements in efficiency can be expected by utilizing additives such as CsI, CsPbI3, and CsPbBr3.

[0176] It was confirmed that stability was secured even at a wide-bandgap PVSK (~1.7 eV).

[0177] Figure 10 is a photograph showing the storage stability of FAOx (FA COOCOOH) and FA2Ox (FA(COO)2) based precursor solutions according to the present invention.

[0178] Photograph 1 was observed on the first day of the experiment, and Ref is a solution composed of FAPbI3800mg (100 mol%) + MAPbBr330mg (5 mol%) + MACI 28mg (35 mol%) and 1mL of DMF:DMSO (8:2).

[0179] The samples listed as targets are those in which FAOx (FA COOCOOH) and FA2Ox (FA(COO)2) were added instead of MACl in the above Ref, in order from left to right.

[0180] Photograph 2 is the sample of Photograph 1 stored for 1 day under harsh conditions of 85°C.

[0181] Photo 3 is the result of filtering the Ref of Photo 2 and FA2Ox (FA (COO)2).

[0182] Photograph 4 shows the filtered Ref and FA2Ox (FA (COO)2) observed on the 2nd day of the experiment, and Photograph 5 shows the observation on the 3rd day.

[0183] Among FA oxalates, FAOx(FA COOCOOH) is acidified in the presence of COOH, and I - It promoted the oxidation of

[0184] It was confirmed that among FA oxalates, FA2Ox (FA (COO)2) contributes to solution stability, similar to FAHCOO.

[0185] As shown in photo 2 of Fig. 10, 85 to reduce time o Accelerated testing was conducted under harsh conditions, and it was confirmed that there were no abnormalities in the solution.

[0186] As a result of additional experiments on the stabilizers used instead of FAHCOO, FAOx(FA COOCOOH) changed color. FA2Ox (FA(COO)2) was determined to be as stable as FAHCOO.

[0187] Figure 11 is a photograph showing the change in a precursor solution with Ref and FAHCOO 0 to 40 mol% added under harsh conditions at 85°C.

[0188] Ref is a precursor solution composed of 1 mL of DMF:DMSO (8:2) with 3800 mg (100 mol%) of FAPbI + 330 mg (5 mol%) of MAPbBr + 28 mg (35 mol%) of MACl.

[0189] The target solution composition is a precursor solution consisting of FAPbI 3800 mg (100 mol%) + CsI 57 mg (17.5 mol%) + PbI 287 mg (15 mol%) + FAHCOO x mg (0~40 mol%) and 1 mL of DMF:DMSO (8:2).

[0190] At first, all the solutions appeared bright yellow.

[0191] However, after aging the solution, the solutions of Ref and F0 (FAHCOO-free) are I - The solution turned red due to the formation of I2 from the oxidation of [the substance].

[0192] It can be confirmed that the solution remains stable in the case of FAHCOO 2.5~40 mol%.

[0193] Figure 12 is a graph showing the change of the precursor solution in Figure 11.

[0194] The physical properties related to this are listed in Tables 5 and 6.

[0195] [Table 5]

[0196]

[0197] [Table 6]

[0198]

[0199] When FAHCOO was added, the solution did not show a visible color change.

[0200] When the amount of FAHCOO was small (<5 mol%), no visible color change of the solution was observed, but it was confirmed that it could not be maintained stably as the efficiency was 13% or less.

[0201] In particular, it can be confirmed that stable efficiency is achieved when the amount of FAHCOO is 5 to 15 mol%.

[0202] It can be observed that when the amount of FAHCOO exceeds 20 mol%, a decrease in efficiency occurs immediately after the solution is prepared.

[0203] Figure 13 is a photograph showing the change in the precursor solution with Ref and FA2Ox added under harsh conditions of 85°C.

[0204] Figure 14 is the material property graph of Figure 13.

[0205] The physical properties related to this are listed in Table 7.

[0206] [Table 7]

[0207]

[0208] The precursor solution with added FA2Ox is a solution composed of 1 mL of DMF:DMSO (8:2) with 3800 mg (100 mol%) FAPbI + 330 mg (5 mol%) MAPbBr + 28 mg (35 mol%) FA2Ox, similar to the sample in Fig. 10.

[0209] The solutions of Rf and F0 (FAHCOO-free) showed a reddening phenomenon.

[0210] In the case of FA2Ox, due to solubility issues, the solution was stirred for 30 minutes after preparation, filtered, and then used and stored.

[0211] It was confirmed that the FA2Ox additive stably maintains a bright yellow color even after aging.

[0212] Although the present invention has been described above with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration according to the present invention were not explicitly described while explaining the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized.

Claims

1. Perovskite particles represented by Chemical Formula 1; and Includes reducing anions; and A perovskite precursor solution containing 5 to 25 mol% of reducing anions relative to 100 mol% of the above perovskite particles: [Chemical Formula 1] AMX3 A is the formamidinium cation (HC(NH2)2) + ) and M is a divalent metal cation, and X is a halide.

2. In Paragraph 1, The above reducing anion is formate (HCOO - A perovskite precursor solution containing one or more of ) and oxalate.

3. In Paragraph 1, A perovskite precursor solution further comprising 1 to 20 mol% of CsI and 7.5 to 20 mol% of PbI with respect to 100 mol% of the above perovskite particles.

4. In Paragraph 1, A perovskite precursor solution further comprising CsPbBr30 to 5 mol% with respect to 100 mol% of the above perovskite particles.

5. In Paragraph 1, The above M is Pb2 + A perovskite precursor solution containing 6. In Paragraph 1, The above X is I - A perovskite precursor solution containing 7. In Paragraph 1, A perovskite precursor solution containing an α-phase.

8. A step of mixing perovskite particles represented by Chemical Formula 1 with a reducing anion, and A method for preparing a perovskite precursor solution by mixing 5 to 25 mol% of reducing anions with respect to 100 mol% of the above perovskite particles: [Chemical Formula 1] AMX3 A is the formamidinium cation (HC(NH2)2) + ) and M is a divalent metal cation, and X is a halide.

9. In Paragraph 8, The above reducing anion is formate (HCOO - A method for preparing a perovskite precursor solution comprising one or more of ) and oxalate.

10. In Paragraph 8, A method for preparing a perovskite precursor solution comprising the above-mentioned reducing anion FAHCOO, which is formed by the reaction of formamidine (FA) acetic acid and formic acid.

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