Perovskite material for solar cell with improved storage stability, and method for preparing same

Abstract

Disclosed are a perovskite material for a solar cell, the perovskite material having improved storage stability due to the addition of CsI, and a method for preparing same. A method for preparing a perovskite material according to the present invention comprises the steps of: (a) mixing cesium iodide (CsI), formamidinium iodide (FAI), and lead iodide (PbI2); (b) adding an organic solvent to the mixed mixture and then stirring at 100-140°C; and (c) filtering the stirred black powder under reduced pressure and then drying to prepare a CsdFAePbI3 (d+e=1) perovskite material.

Description

Perovskite material for solar cells with improved storage stability and method for manufacturing the same

[0001] The present invention relates to a perovskite material for solar cells with improved solid-state storage stability by adding CsI, and a method for manufacturing the same.

[0002] The rapid expansion of the field of photovoltaic (PSC) research 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] Organic / inorganic perovskite compounds, considered to be key materials for solar cells, consist of an organic or metal monovalent cation (A), a metal divalent cation (B), and a halogen anion (X).

[0006] Perovskite is represented by the chemical formula ABX3 and exhibits polymorphic characteristics with various crystal structures depending on ABX3.

[0007] In particular, FAPbI3, a representative perovskite material, has a photoactive diamond (cubic) crystal structure α-phase and a photoinactive hexagonal crystal structure α-phase.

[0008] A method for preparing α-phase FAPbI3 involves preparing α-phase FAPbI3 from a metal halide PbI2 and an organic halide FAI precursor.

[0009] α-phase FAPbI3 can also be obtained by adjusting the heating temperature.

[0010] Since δ-phase FAPbI3 is yellow and α-phase FAPbI3 is black, the δ-phase and α-phase can be easily distinguished with the naked eye.

[0011] Since FAPbI3 is a thermodynamically stable substance in the δ-phase, α-phase FAPbI3 exhibits a tendency to return to the δ-phase.

[0012] α-phase FAPbI3 undergoes a phase transition when in contact with moisture or impurities, which can be easily observed visually through a change in the color of the powder.

[0013] As such, the sensitivity of perovskites to moisture and impurities makes storage conditions demanding, and their low stability inevitably limits their shelf life.

[0014] Such deformation of perovskites is a critical factor that reduces the performance index and efficiency of organic / inorganic perovskite photoactive layer thin films and solar cells.

[0015] Therefore, there is a need for research on perovskites for solar cells with improved stability.

[0016] The objective of the present invention is to provide a perovskite material for solar cells with improved solid-state storage stability and a method for manufacturing the same.

[0017] 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.

[0018] A method for manufacturing a perovskite material according to the present invention comprises: (a) mixing cesium iodide (CsI), formamidinium iodide (FAI), and lead iodide (PbI2); (b) adding an organic solvent to the mixed mixture and stirring at 100 to 140°C; and (c) filtering the stirred black powder under reduced pressure and drying it to obtain Cs d FA e It is characterized by including the step of manufacturing a PbI3(d+e=1) perovskite material.

[0019] In step (a) above, cesium iodide (CsI):formamidinium iodide (FAI):lead iodide (PbI2) can be mixed in a molar ratio of 0.05 to 0.4:1:1.04 to 1.4.

[0020] The above Cs d FA e PbI3 perovskite may contain an α-phase.

[0021] In step (c) above, Cs d FA e PbI3(0.04 ≤ d ≤ 0.2, 0.8 ≤ e ≤ 0.96) may be.

[0022] In step (c) above, drying can be performed at 120 to 170°C.

[0023] The perovskite material according to the present invention is Cs d FA e It is characterized by being represented as PbI3(0.04 ≤ d ≤ 0.2, 0.8 ≤ e ≤ 0.96).

[0024] The above perovskite material may include an α-phase.

[0025] When the above perovskite material is stored at 23°C and 60% (RH relative humidity) for 100 hours and then observed visually, there may be no change in the color of the perovskite.

[0026] When the above perovskite material is stored at 23°C and 60% (RH relative humidity) for 100 hours and then observed visually, the rate of change in current density according to voltage of the perovskite material may be 1% or less.

[0027] A solar cell according to the present invention is characterized by comprising: a first electrode; a hole transport layer disposed on the first electrode and having a change in resistance in response to short-wavelength infrared radiation; a photoactive layer disposed on the hole transport layer and comprising the aforementioned perovskite material; an electron transport layer disposed on the photoactive layer and having a change in resistance in response to short-wavelength infrared radiation; and a second electrode.

[0028] The perovskite material for solar cells and the method for manufacturing the same according to the present invention have the effect of excellent storage stability in atmospheric conditions.

[0029] In particular, the perovskite material of the present invention has the characteristic that there is almost no change in color or change in current density according to voltage even when stored for 100 hours under constant temperature and humidity conditions.

[0030] 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.

[0031] Figure 1 is a photograph comparing the color change of perovskite materials after storing Example 1 and Comparative Example 1 according to the present invention for 100 hours under constant temperature and humidity conditions.

[0032] Figure 2 shows the XRD data results before and after storing Example 1 and Comparative Example 1 according to the present invention for 100 hours under constant temperature and humidity conditions.

[0033] Figure 3 is a graph of current density according to voltage before and after storing Example 1 and Comparative Example 1 according to the present invention for 100 hours under constant temperature and humidity conditions.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] Hereinafter, a perovskite material for solar cells with improved storage stability and a method for manufacturing the same, according to some embodiments of the present invention, will be described.

[0038] A method for manufacturing a perovskite material according to the present invention comprises: (a) mixing cesium iodide (CsI), formamidinium iodide (FAI), and lead iodide (PbI2); (b) adding an organic solvent to the mixed mixture and stirring at 100 to 140°C; and (c) filtering the stirred black powder under reduced pressure and drying it to obtain Cs d FA e It is characterized by including a step of manufacturing a PbI3 perovskite material.

[0039] First, as a precursor raw material, cesium iodide (CsI) : formamidinium iodide (FAI) : lead iodide (PbI2) can be mixed in a molar ratio of 0.05 to 0.4 : 1 : 1.04 to 1.4.

[0040] Preferably, cesium iodide (CsI) : formamidinium iodide (FAI) : lead iodide (PbI2) can be mixed in a molar ratio of 0.05 to 0.25 : 1 : 1.04 to 1.21.

[0041] Csium iodide (CsI) : formamidinium iodide (FAI) : lead iodide (PbI2) satisfies a molar ratio of 0.05 ~ 0.4 : 1 : 1.04 ~ 1.4, thereby providing excellent storage stability. d FA e It has a favorable effect in manufacturing PbI3 perovskite materials.

[0042] In particular, if the molar ratio of lead iodide (PbI2) exceeds 1.4, lead iodide (PbI2) does not dissolve well in organic solvents, so it remains in the perovskite and can act as an impurity.

[0043] Therefore, it is desirable to satisfy a molar ratio of 0.05 to 0.4 of cesium (CsI) and a molar ratio of 1.04 to 1.4 of lead iodide (PbI2).

[0044] Next, an organic solvent can be added to the mixed mixture and stirred at 100 to 140°C.

[0045] Organic solvents may include 2-methoxyethanol, methanol, acetone, ethanol, etc.

[0046] Preferably, stirring can be done at 110 to 130°C.

[0047] As the temperature rises during the reaction, it sequentially changes into a clear yellow solution, a cloudy yellow solution, and a solution with black powder precipitated.

[0048] The change from clear yellow to cloudy yellow is the process of solid precipitation, and the change from cloudy yellow to black is the process of changing from the δ-phase to the α-phase.

[0049] The temperature at which the phase changes is approximately between 110 and 115°C, and this can be confirmed visually through the color of the powder during the reaction.

[0050] If the stirring temperature is below 100℃, complete conversion to the α-phase may not occur.

[0051] Conversely, if the stirring temperature exceeds 140℃, there is a possibility that the organic solvent will evaporate due to the high boiling point of the organic solvent.

[0052] The evaporation of such organic solvents reduces reactivity and can cause impurities dissolved in the organic solvent to precipitate; therefore, reflux using a condenser column can prevent the evaporation of the organic solvent.

[0053] Black powder is produced by the above stirring step, and after the reaction mixture is naturally cooled, ethyl acetate can be added to perform additional precipitation.

[0054] When the reaction is complete, most of the powder precipitates, but some remains dissolved in the organic solvent. Since organic solvents such as ethyl acetate have no solubility for perovskite, when ethyl acetate is added, substances dissolved in ethyl acetate may precipitate due to the difference in solubility.

[0055] Therefore, when synthesizing perovskite materials, it is desirable to perform additional precipitation to obtain a high yield of over 90%.

[0056] This ethyl acetate can also be used as a washing solvent when filtering powder in the synthesis process.

[0057] Subsequently, the stirred black powder is filtered under reduced pressure and dried to obtain Cs d FA e PbI3 perovskite material can be manufactured.

[0058] Drying can be performed at 120 to 170°C, and preferably at 140 to 160°C.

[0059] As such, the present invention can improve the storage stability of perovskite materials by adding cesium iodide (CsI) as a precursor raw material.

[0060] The manufactured perovskite material is Cs d FA e It has a PbI3 structure (0.04 ≤ d ≤ 0.2, 0.8 ≤ e ≤ 0.96), and preferably Cs d FA e It can have the structure PbI3 (0.04 ≤ d ≤ 0.17, 0.83 ≤ e ≤ 0.96). Here, the sum of the molar ratios of Cs and FA must be 1.

[0061] The above Cs d FA eThe PbI3 perovskite material contains an α-phase and has excellent storage stability, as there is no change in current density or color with respect to voltage compared to the existing FAPbI3 perovskite material even when stored under constant temperature and humidity conditions.

[0062] The perovskite material according to the present invention is Cs d FA e It is characterized by being represented as PbI3(0.04 ≤ d ≤ 0.2, 0.8 ≤ e ≤ 0.96).

[0063] Perovskite materials may include an α-phase, and since this is the same as described above, it will be omitted.

[0064] The average particle size of the perovskite material may be 0.1 to 2 μm, but is not limited thereto.

[0065] The perovskite material of the present invention exhibits excellent storage stability under constant temperature and humidity conditions, and this effect means that efficiency is maintained even under indoor storage conditions and there is minimal change in color over time.

[0066] From this perspective, the storage stability of perovskite materials can be verified by color change under constant temperature and humidity conditions and the rate of change in current density according to voltage.

[0067] When the perovskite material is stored at 23°C and 60% (RH relative humidity) for 100 hours and then observed visually, there may be no change in the color of the perovskite.

[0068] For example, a black powder perovskite material can exhibit black powder even after being exposed to a constant temperature and humidity atmosphere.

[0069] When the perovskite material is stored at 23°C and 60% (RH relative humidity) for 100 hours and then observed visually, the rate of change in current density according to voltage of the perovskite material may be 1% or less.

[0070] For example, a perovskite material with a 94% yield can exhibit a yield of 93 to 94% even after being exposed to a constant temperature and humidity atmosphere.

[0071] Generally, solar panels have a structure in which multiple PN junctions are gathered together.

[0072] The surface of the solar panel is coated with a special non-reflective, transmittable coating, so when sunlight reaches the surface, it is absorbed into the panel without being reflected.

[0073] When sunlight is absorbed into the solar panel, silicon atoms absorb energy, and electrons become activated.

[0074] Activated electrons try to move from P-type silicon to N-type silicon.

[0075] At this time, electrons move through a channel called an electron hole in the PN junction, and in this process, the electrons generate electrical energy. This generated electrical energy can be transferred to the outside through wires inside the battery plate and used.

[0076] Additionally, efficiency can be improved by adding a quantum dot transport layer.

[0077] Short-wavelength and long-wavelength light of the illuminated spectrum are absorbed by the perovskite of the top cell and the silicon of the bottom cell, respectively, and electrons and holes generated in the perovskite solar cell recombine at the interface between the ITO layer and the Au layer of the perovskite.

[0078] A solar cell according to the present invention is characterized by comprising a first electrode, a hole transport layer disposed on the first electrode and having a change in resistance in response to short-wavelength infrared radiation, a photoactive layer disposed on the hole transport layer and comprising the aforementioned perovskite material, an electron transport layer disposed on the photoactive layer and having a change in resistance in response to short-wavelength infrared radiation, and a second electrode.

[0079] A solar cell comprises a hole transport layer whose resistance changes in response to short-wavelength light, a photoactive layer disposed on the hole transport layer, and an electron transport layer disposed on the photoactive layer whose resistance changes in response to short-wavelength light.

[0080] Assuming the first electrode is a transparent electrode, light passes through the first electrode and is irradiated onto the photoactive layer. As light is irradiated onto the photoactive layer, electron-hole pairs are formed in the photoactive layer, and among these, the holes move to the first electrode and are output.

[0081] Electron-hole pairs are formed in the photoactive layer by light irradiated onto the photoactive layer through the first electrode, and the generated holes flow to the first electrode via the valence band of the hole transport layer.

[0082] The first electrode may include one or more of Au, Ag, Pt, Ni, Cu, In, Ru, Pd, Rh, Mo, Ir, and Os.

[0083] 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 photoactive layer from external factors such as humidity.

[0084] To date, the most commonly used hole transport layers in perovskite solar cells are materials called Spiro-OMeTAD and PTAA.

[0085] 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.

[0086] Such organic-based materials are widely used in perovskite solar cells because they are soluble in non-polar solvents that do not damage the photoactive layer and do not require heat treatment.

[0087] PTAA, a polymer, has a higher hole mobility than other polymer materials due to the inherent characteristic of having many holes.

[0088] PTAA possesses multiple benzene rings, and its pi (ð) conjugated structure forms the channels necessary for hole transport. It is capable of appropriate energy level matching with perovskite, providing excellent hole extraction and electron backflow prevention capabilities.

[0089] The photoactive layer contains perovskite that forms electron-hole pairs in response to short-wavelength light, and electrons generated in the photoactive layer flow to the electrode through the electron transport layer.

[0090] 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.

[0091] The electron transport layer is located between the transparent conductive oxide (TCO) substrate and the perovskite-containing photoactive layer.

[0092] The electron transport layer transports electrons excited in the perovskite photoactive layer to the transparent conductive glass substrate and blocks the penetration of holes to prevent recombination.

[0093] As such, the electron transport layer (ETL) plays a role in transporting electrons, and to further facilitate the movement of these electrons, a thin film of TiO2 can be placed on the electron transport layer (ETL).

[0094] The electron transport layer changes its resistance in response to short-wavelength light, which amplifies the output current and can improve absorbance and luminescence characteristics.

[0095] For efficient electron injection and transport, characteristics such as fast electron mobility, as well as the compatibility of the photoactive layer and band structure, are required.

[0096] The electron transport layer may include one or more of TiO2, ZrO, Al2O3, SnO2, ZnO, WO3, Nb2O5, and TiSrO3, and preferably may include TiO2.

[0097] Electrons generated in the photoactive layer flow to the second electrode through the electron transport layer.

[0098] The second electrode may include one or more of FTO, ITO, IZO, ZnO-Ga2O3, ZnO-Al2O3, and SnO2-Sb2O3.

[0099] In the step of sequentially forming a first electrode, a hole transport layer, a photoactive layer including the perovskite material, an electron transport layer, and a second electrode on a counter electrode substrate, each layer can be formed using a known method.

[0100] For example, it can be formed by selecting any one of spin coating, bar coating, inkjet printing, nozzle printing, spray coating, slot die coating, gravure printing, screen printing, electrohydrodynamic jet printing, or electrospray.

[0101] Specific examples regarding the perovskite for solar cells with improved storage stability and the method for manufacturing the same are as follows.

[0102] 1. Manufacturing of perovskite materials

[0103] Example 1

[0104] 25.8g of raw material formamidinium iodide (FAI), 79.5g of lead iodide (PbI2), and 6.8g of cesium iodide (CsI) were placed in a reactor, 150ml of 2-methoxyethanol was added, and the mixture was stirred to dissolve it.

[0105] Afterwards, the reaction was carried out by heating at 120°C for 2 hours. A condenser column was installed in the reactor to prevent the solvent from evaporating. When the reaction was complete, the precipitated black powder was checked.

[0106] After naturally cooling the reaction mixture to 50°C, 450 ml of ethyl acetate, a reaction solvent, was added to proceed with further precipitation.

[0107] The precipitated powder was filtered under reduced pressure using a filter funnel. 450 ml of ethyl acetate was added to the solvent-removed powder, and the mixture was washed three times. The remaining solvent was removed by filtering under reduced pressure for 20 minutes. The solvent-removed powder was transferred to a glass dish and subjected to reduced pressure drying in a vacuum dryer at 150°C for more than 15 hours to obtain 108 g of perovskite, with a yield of 96.3%.

[0108] The molar ratios of the raw materials are CsI 0.175, FAI 1, and PbI 21.15, and the molar ratio of the final product is Cs 0.13 FA 0.87 PbI3 am.

[0109] Next, the measurement of physical properties was carried out as follows.

[0110] 10g of the perovskite from Example 1 was placed in a 20ml glass vial and stored at room temperature with the lid open, allowing it to come into continuous contact with moisture and oxygen.

[0111] At this time, the indoor storage environment is 21–23℃ and the humidity is 34–65% (RH relative humidity). The storage period is approximately 100 hours.

[0112] Solar cell devices were fabricated using indoor-stored perovskite inside a constant temperature and humidity chamber (20℃ / 20%), and their physical properties were measured.

[0113] To manufacture a solar cell device, a 1-inch square glass coated with ITO was used as a substrate, and an electron transport layer was formed by spin coating an aqueous solution of nanoparticle tin oxide.

[0114] An ink was prepared by dissolving the perovskite from Example 1 at a concentration of 1.4 M in a mixed solvent of dimethyl formamide and dimethyl sulfoxide (8:1 volume ratio). A thin film was formed by spin-coating the ink and heat-treating it. The hole transport layer used Sprio-OMeTAD, dissolved in chlorobenzene, and formed by spin-coating. The top electrode used gold and was formed to a thickness of 70 nm using a vacuum thermal evaporator.

[0115] The IV of the completed solar cell device was measured and the efficiency was calculated using a solar simulator and a source meter that meet Class AAA certification standards.

[0116] Solar cell elements not exposed to the outside air showed an efficiency of 19.06%, and solar cell elements stored indoors and exposed to the outside air showed an efficiency of 19.09%, confirming that there was no decrease in efficiency.

[0117] Example 2

[0118] 25.8g of raw material formamidinium iodide (FAI), 83.67g of lead iodide (PbI2), and 9.7g of cesium iodide (CsI) were added; 113.1g of perovskite was obtained with a yield of 94.9%; the molar ratios of the raw materials are CsI 0.25, FAI 1, PbI2 1.21, and the molar ratio of the final product is Cs 0.17 FA 0.83 PbI3 It was manufactured under the same conditions as Example 1, except for the point.

[0119] As a result of measurement under the same conditions as Example 1, the solar cell element not exposed to the outside air showed an efficiency of 18.41%, and the solar cell element stored indoors and exposed to the outside air showed an efficiency of 18.43%, confirming that there was no decrease in efficiency.

[0120] Example 3

[0121] 25.8g of raw material formamidinium iodide (FAI), 80.91g of lead iodide (PbI2), and 7.8g of cesium iodide (CsI) were added; 109.7g of perovskite was obtained with a yield of 94.9%; the molar ratios of the raw materials are CsI 0.2, FAI 1, and PbI2 1.17, and the molar ratio of the final product is Cs 0.15 FA 0.85 It was prepared under the same conditions as Example 1, except that it was PbI3.

[0122] As a result of measurements taken under the same conditions as in Example 1, the solar cell element not exposed to the outside air showed an efficiency of 18.60%, and the solar cell element stored indoors and exposed to the outside air showed an efficiency of 18.58%, confirming that there was no decrease in efficiency.

[0123] Example 4

[0124] 25.8g of raw material formamidinium iodide (FAI), 83g of lead iodide (PbI2), and 5.9g of cesium iodide (CsI) were added; 108g of perovskite was obtained with a yield of 94.2%; the molar ratios of the raw materials are CsI 0.15, FAI 1, and PbI2 1.12, and the molar ratio of the final product is Cs 0.11 FA 0.89 It was prepared under the same conditions as Example 1, except that it was PbI3.

[0125] As a result of measurement under the same conditions as Example 1, the solar cell element not exposed to the outside air showed an efficiency of 19.19%, and the solar cell element stored indoors and exposed to the outside air showed an efficiency of 19.13%, confirming that there was no decrease in efficiency.

[0126] Example 5

[0127] 25.8g of raw material formamidinium iodide (FAI), 76.07g of lead iodide (PbI2), and 4.9g of cesium iodide (CsI) were added; 103.1g of perovskite was obtained with a yield of 96.6%; the molar ratios of the raw materials are CsI 0.125, FAI 1, and PbI2 1.1, and the molar ratio of the final product is Cs 0.09 FA 0.91 It was prepared under the same conditions as Example 1, except that it was PbI3.

[0128] As a result of measurement under the same conditions as Example 1, the solar cell element not exposed to the outside air showed an efficiency of 19.31%, and the solar cell element stored indoors and exposed to the outside air showed an efficiency of 19.22%, confirming that there was no decrease in efficiency.

[0129] Example 6

[0130] 25.8g of raw material formamidinium iodide (FAI), 76.68g of lead iodide (PbI2), and 3.9g of cesium iodide (CsI) were added; 99.2g of perovskite was obtained with a yield of 95.1%; the molar ratios of the raw materials are CsI 0.1, FAI 1, and PbI2 1.08, and the molar ratio of the final product is Cs 0.07 FA 0.93 It was prepared under the same conditions as Example 1, except that it was PbI3.

[0131] As a result of measurement under the same conditions as Example 1, the solar cell element not exposed to the outside air showed an efficiency of 19.50%, and the solar cell element stored indoors and exposed to the outside air showed an efficiency of 19.39%, confirming that there was no decrease in efficiency.

[0132] Example 7

[0133] 25.8g of raw material formamidinium iodide (FAI), 71.92g of lead iodide (PbI2), and 2g of cesium iodide (CsI) were added; 95.7g of perovskite was obtained with a yield of 96.1%; the molar ratios of the raw materials are CsI 0.05, FAI 1, and PbI2 1.04, and the molar ratio of the final product is Cs 0.04 FA 0.96 It was prepared under the same conditions as Example 1, except that it was PbI3.

[0134] As a result of measurement under the same conditions as Example 1, the solar cell element not exposed to the outside air showed an efficiency of 19.65%, and the solar cell element stored indoors and exposed to the outside air showed an efficiency of 19.42%, confirming that there was no decrease in efficiency.

[0135] Comparative Example 1

[0136] In the synthesis process without the raw material cesium iodide, the equivalent ratio of the precursor materials, formamidinium iodide and lead iodide, was formed at an equal molar ratio of 1:1.

[0137] It was prepared under the same conditions as Example 1, except that 25.8g of raw material formamidinium iodine (FAI) and 69.15g of lead iodide (PbI2) were added, 90.5g of perovskite was obtained with a yield of 95.3%, the molar ratio of the raw materials was FAI 1, PbI21, and the final product was FAPbI3.

[0138] As a result of measurements taken under the same conditions as in Example 1, the solar cell element not exposed to the outside air showed a rapid decrease in efficiency with an efficiency of 20.84%, while the solar cell element stored indoors and exposed to the outside air showed an efficiency of 14.30%.

[0139] Comparative Example 2

[0140] The molar ratio of the raw materials is CsI 0.5, FAI 1, PbI 21.425, and the molar ratio of the final product is Cs 0.3 FA 0.7It was prepared under the same conditions as Example 1, except that it was PbI3.

[0141] It was impossible to manufacture ink at this ratio. Due to the excessive cesium content, the powder did not dissolve completely in the solvent.

[0142] The results of Examples 1 to 7 and Comparative Examples 1 and 2 are summarized and described in Table 1.

[0143] [Table 1]

[0144]

[0145] Figure 1 is a photograph comparing the color change of perovskite after storing Example 1 and Comparative Example 1 according to the present invention for 100 hours under constant temperature and humidity conditions.

[0146] 10g of the synthesized product was placed in 20ml glass vials and stored at room temperature without closing the lids to allow continuous contact with moisture and oxygen.

[0147] The indoor storage environment is 21–23°C, and the humidity is 34–65% (RH relative humidity). The exposure time is 100 hours.

[0148] It was confirmed that the cesium-free FAPbI3 of Comparative Example 1 turned yellow. In contrast, the CsFAPbI3 of Example 1 showed no visible change in color.

[0149] Therefore, the perovskite of the present invention has the effect of having little change over time.

[0150] Figure 2 shows the XRD data results before and after storing Example 1 and Comparative Example 1 according to the present invention for 100 hours under constant temperature and humidity conditions.

[0151] 10g of the synthesized product was placed in each 20ml glass vial and stored indoors without closing the lid to allow continuous contact with moisture and oxygen. The indoor storage environment was 21–23℃ and humidity was 34–65% (RH relative humidity). The exposure time was 100 hours.

[0152] The degree of material deformation was confirmed through XRD measurements after exposure.

[0153] The cesium-free FAPbI3 of Comparative Example 1 was confirmed to have completely transformed into the δ-phase. In contrast, no material transformation was observed in the CsFAPbI3 of Example 1, even in the XRD data.

[0154] CsFAPbI3 is a form in which CsPbI3 is mixed with α-phase FAPbI3 in the perovskite crystal structure, and the peaks appearing between 25° and 27° in the XRD data are the CsPbI3 peaks.

[0155] Figure 3 is a graph of current density according to voltage before and after storing Example 1 and Comparative Example 1 according to the present invention for 100 hours under constant temperature and humidity conditions.

[0156] The Newport 94083A model was used as the measuring instrument, the Keithley 2460 source meter was used to measure the IV value of the device, and the OMA product was used as the measuring jig to connect and fix the electrodes of the sample device.

[0157] 10g of the synthesized product was placed in each 20ml glass vial and stored indoors without closing the lid to allow continuous contact with moisture and oxygen. The indoor storage environment was 21–23℃ and humidity was 34–65% (RH relative humidity). The exposure time was 100 hours.

[0158] It shows the efficiency of the fabricated device according to exposure time and material conditions.

[0159] In the solar cell using FAPbI3 that does not contain cesium in Comparative Example 1, a rapid decrease in device efficiency is observed in the modified material.

[0160] On the other hand, in the case of the solar cell device using CsFAPbI3 of Example 1, no decrease in efficiency occurred in the device fabricated using the material exposed to the outside for 100 hours.

[0161] 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. (a) mixing cesium iodide (CsI), formamidinium iodide (FAI), and lead iodide (PbI2); and (b) a step of adding an organic solvent to the above-mentioned mixed mixture and stirring at 100 to 140°C; and (c) After filtering the above stirred black powder under reduced pressure, dry it to obtain Cs d FA e A method for manufacturing a perovskite material comprising the step of manufacturing a PbI3(d+e=1) perovskite material.

2. In Paragraph 1, A method for manufacturing a perovskite material by mixing cesium iodide (CsI):formamidinium iodide (FAI):lead iodide (PbI2) in a molar ratio of 0.05 to 0.4:1:1.04 to 1.4 in step (a) above.

3. In Paragraph 1, The above Cs d FA e A method for manufacturing a perovskite material containing an α-phase, wherein the PbI3 perovskite material is a perovskite material.

4. In Paragraph 1, In step (c) above, Cs d FA e Method for manufacturing a perovskite material of PbI3 (0.04 ≤ d ≤ 0.2, 0.8 ≤ e ≤ 0.96).

5. In Paragraph 1, A method for manufacturing a perovskite material in which, in step (c) above, drying is performed at 120 to 170°C. 6.Cs d FA e A perovskite material represented by PbI3 (0.04 ≤ d ≤ 0.2, 0.8 ≤ e ≤ 0.96).

7. In Paragraph 6, Perovskite material containing an α-phase.

8. In Paragraph 6, A perovskite material that shows no color change when observed visually after storing the above perovskite material at 23℃ and 60% (RH relative humidity) for 100 hours.

9. In Paragraph 6, A perovskite material having a current density change rate of 1% or less with respect to voltage when the perovskite material is visually observed after being stored at 23℃ and 60% (RH relative humidity) for 100 hours.

10. First electrode; A hole transport layer disposed on the first electrode above, the resistance of which changes in response to short-wavelength infrared rays; A photoactive layer disposed on the hole transport layer above and comprising a perovskite material according to claim 6; An electron transport layer disposed on the above photoactive layer and having a change in resistance in response to short-wavelength infrared rays; and A solar cell comprising a second electrode.

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