Method for synthesizing delta-phase perovskite crystals and delta-phase perovskite crystals produced by this method

Abstract

The present invention relates to a method for producing a delta-phase perovskite crystal, and more specifically to a novel method for synthesizing a delta-phase perovskite crystal in high yield and a delta-phase perovskite crystal produced using the same.

Description

[Technical Field]

[0001] The present invention relates to a method for producing delta-phase perovskite crystals in high yield and with high purity, and to delta-phase perovskite crystals produced using the method. [Background technology]

[0002] In order to solve the global environmental problems caused by the depletion and use of fossil energy, active research is being conducted into renewable and clean alternative energy sources such as solar energy, wind power, and hydropower.

[0003] Among these, interest in solar cells, which directly convert sunlight into electrical energy, has increased significantly. Here, a solar cell refers to a cell that absorbs light energy from sunlight and generates current and voltage using the photovoltaic effect, which generates electrons and holes.

[0004] Currently, it is possible to manufacture np diode-type silicon (Si) single crystal-based solar cells with a light energy conversion efficiency of over 20% and they are actually used in solar power generation, and there are also solar cells that use compound semiconductors such as gallium arsenide (GaAs) that have even better conversion efficiency. However, these inorganic semiconductor-based solar cells require highly refined materials to achieve high efficiency, which consumes a lot of energy to refine the raw materials, and the process of turning the raw materials into single crystals or thin films requires expensive processing equipment, which limits the reduction in solar cell manufacturing costs and has been an obstacle to large-scale use.

[0005] Therefore, in order to manufacture solar cells at low cost, it is necessary to significantly reduce the costs of the materials and manufacturing processes used as the core of solar cells. As such, research is being conducted on perovskite solar cells, which can be manufactured using low-cost materials and processes, as an alternative to inorganic semiconductor-based solar cells.

[0006] The general structural formula of perovskite is an AMX3 structure, in which anions are located at the X sites, large cations are located at the A sites, and small cations are located at the M sites.

[0007] These perovskite compounds have excellent electrical conductivity, charge mobility, and optical properties, and are widely applicable. They also have a variety of features, including a long lifespan, a high absorption wavelength spectrum due to a small energy band gap, and a wide charge carrier diffusion length. At the same time, they are economical in terms of material cost, can be processed as a solution, and have advantages such as low processing costs and the ability to be produced using low-temperature processes. As such, they are attracting attention as promising materials for renewable energy applications, and research is ongoing into their use as light absorbers in perovskite solar cells.

[0008] The conventional synthesis method for producing perovskite crystals with the ABX3 structure (A = monovalent organic cation, B = divalent metal cation, X = halogen ion) involves synthesizing ABX3 from AX and BX2 in a solvent at high temperature, followed by filtering and drying. However, this method is not suitable for mass production due to its low synthesis yield, and is limited by the low yield caused by the generation of unnecessary by-products during the synthesis of AX, the precursor used in the synthesis. Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention has been devised to overcome the above-mentioned problems, and aims to provide a method for producing delta-phase perovskite crystals in high yield and / or high purity using precursors different from those already known, which is efficient and allows for mass production, and delta-phase perovskite crystals produced by this method. [Means for solving the problem]

[0010] To solve the above-mentioned problems, the present invention relates to a method for producing delta-phase perovskite crystals, which includes the steps of: (1) adding a solvent to a reactor and then adding and dissolving an organic anion precursor represented by the following Chemical Formula 1 and a metal ion precursor represented by the following Chemical Formula 2 into the solvent to produce a reaction solution; (2) heating the reaction solution at 20 to 110°C until the reaction solution turns yellow, and then adding an anti-solvent to obtain a solution containing a precipitate; (3) removing the colorless solution from the solution containing the precipitate from Step 2 and then performing a primary wash of the precipitate with a bad solvent; (4) performing a secondary wash of the primary washed precipitate with an ether-based solvent and filtering to obtain a filtrate; and (5) drying the filtrate to obtain a delta-phase perovskite crystal represented by the following Chemical Formula 3.

[0011] (chemical formula 1) AX

[0012] (Chemical formula 2) BX2

[0013] (Chemical formula 3) ABX3 In the above Chemical Formula 1 and Chemical Formula 3, A is formamidinium (FA), methylammonium (MA), FA x MA (1-x) (0 <X<1)、またはN(R 1 )4 + and R 1 is a linear alkyl group having 1 to 5 carbon atoms, a branched alkyl group having 3 to 5 carbon atoms, a phenyl group, an alkylphenyl group, or an alkoxyphenyl group, and in the above Chemical Formula 2 and Chemical Formula 3, B is Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Sn 2+ , Pb 2+ , Bi 2+ , Ge 2+ , Ti 2+ ,EU 2+ or Zr 2+and X is I - , Cl - or Br - is.

[0014] In a preferred embodiment of the present invention, the solvent for the first stage may comprise one or more selected from gamma-butyrolactone, gamma-valerolactone, alpha-angelica lactone, alpha-methylene-gamma-butyrolactone, alpha-hydroxy-gamma-butyrolactone, and ε-caprolactone.

[0015] In a preferred embodiment of the present invention, the reaction solution in one step may contain the organic anion precursor and the metal ion precursor in a molar ratio of 0.8 to 1.2:1.

[0016] In a preferred embodiment of the present invention, the non-solvent may include one or more selected from chlorobenzene, toluene, and xylene.

[0017] In a preferred embodiment of the present invention, the anti-solvent may include a nitrile solvent including one or more selected from acetonitrile, propionitrile, and aminopropionitrile.

[0018] In a preferred embodiment of the present invention, the ether solvent may include one or more selected from diethyl ether, methyl tert-butyl ether, diisopropyl ether, and dibutyl ether.

[0019] In a preferred embodiment of the present invention, the delta-phase perovskite crystals obtained through the five steps may have a yield of 75.00% or more and a purity of 99.00% or more, preferably a yield of 82.00% or more and a purity of 99.00% or more, and more preferably a yield of 90.00% or more and a purity of 99.00% or more.

[0020] Another object of the present invention is a delta-phase perovskite crystalline body prepared by the above method, wherein the perovskite complex may be a perovskite crystalline body represented by the following Chemical Formula 3:

[0021] (Chemical formula 3) ABX3 In the above formula 3, A is formamidinium (FA), methylammonium (MA), FA x MA (1-x) (0 <X<1)、またはN(R 1 )4 + and R 1 is a linear alkyl group having 1 to 5 carbon atoms, a branched alkyl group having 3 to 5 carbon atoms, a phenyl group, an alkylphenyl group, or an alkoxyphenyl group, and B is Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Sn 2+ , Pb 2+ , Bi 2+ , Ge 2+ , Ti 2+ ,EU 2+ or Zr 2+ and X is I - , Cl - or Br - is.

[0022] Another object of the present invention is to provide a perovskite solar cell that includes the perovskite crystal as a light absorption layer (or photoactive layer). [Effects of the Invention]

[0023] The present invention enables mass production of delta-phase perovskite crystals in high yield and high purity in an economical manner, and the delta-phase perovskite crystals of the present invention can be applied to materials in the electrical, electronic, or optical fields that require high electrical conductivity, charge mobility, and optical properties. As a preferred example, the delta-phase perovskite crystals can be applied to the light absorption layer (photoactive layer) of solar cells. [Brief explanation of the drawings]

[0024] [Figure 1] FIG. 1 is a photograph showing a schematic process for synthesizing the delta-phase perovskite crystal carried out in Example 1. [Figure 2] FIG. 2 shows the results of XRD measurements of the delta-phase perovskite crystals synthesized in Examples 1 to 5 and Comparative Examples 1 to 3, which were carried out by adding a non-solvent under different temperature conditions. [Figure 3] FIG. 3 is a TGA analysis graph for the delta-phase perovskite crystal produced in Example 2. [Figure 4] FIG. 4 shows the results of performance test measurements of the perovskite solar cells produced in Production Examples 1 to 3. DETAILED DESCRIPTION OF THE INVENTION

[0025] The present invention will now be described in more detail.

[0026] The present invention relates to a method for producing a perovskite crystal represented by the following chemical formula 3:

[0027] (Chemical formula 3) ABX3 In the above formula 3, A is formamidinium (FA), methylammonium (MA), FA x MA (1-x) (0 <X<1)、またはN(R 1 )4 +and preferably formamidinium (FA), methylammonium (MA) or FA x MA (1-x) (0 < X < 1), more preferably formamidinium (FA) or methylammonium (MA). And the R 1 is a linear alkyl group having 1 to 5 carbon atoms, a branched alkyl group having 3 to 5 carbon atoms, a phenyl group, an alkylphenyl group or an alkoxyphenyl group, preferably the R 1 is a linear alkyl group having 1 to 5 carbon atoms, more preferably a linear alkyl group having 1 to 2 carbon atoms.

[0028] Also, B in Chemical Formula 3 is Fe 2+ Co 2+ Ni 2+ Cu 2+ Sn 2+ Pb 2+ Bi 2+ Ge 2+ Ti 2+ Eu 2+ [[ID=·32]]or Zr 2+ and preferably Cu 2+ Sn 2+ Pb 2+ Bi<00·00061>Ge 2+ or Ti 2+ and more preferably Sn 2+ Pb 2+ or Bi 2+ is.

[0029] And X in Chemical Formula 3 is I - Cl - or Br - and preferably I - or Cl - more preferably I - is.

[0030] Organic halides such as FAI (formamidinium iodide) are vulnerable to moisture, and purified organic halides are costly. When directly synthesizing organic halides during the synthesis of perovskite (ABX3), considering the low yield of the conventional perovskite synthesis method, it is uneconomical.

[0031] The delta-phase perovskite crystal of the present invention comprises the following steps: after introducing a solvent into a reactor, introducing and dissolving an organic anion precursor represented by the following Chemical Formula 1 and a metal ion precursor represented by the following Chemical Formula 2 into the solvent to produce a reaction solution in a first step; heating the reaction solution at 20 to 110 °C until the reaction solution turns yellow, then introducing an anti-solvent to obtain a solution containing a precipitate in a second step; removing a colorless solution from the solution containing the precipitate in the second step, and then performing a first washing of the precipitate with a bad solvent in a third step; performing a second washing and filtration of the precipitate after the first washing with an ether-based solvent to obtain a filtrate in a fourth step; and drying the filtrate to obtain a delta-phase perovskite crystal represented by the following Chemical Formula 3 in a fifth step; and can be synthesized by performing the included steps.

[0032] (Chemical Formula 1) AX In Chemical Formula 1, A is formamidinium (FA, formamidinium), methylammonium (MA, methylammonium), FA x MA (1-x) (0 < X < 1), or N(R 1 )4 + and preferably, formamidinium (FA, formamidinium), methylammonium (MA, methylammonium) or FA x MA (1-x) (0 < X < 1), and more preferably, formamidinium (FA, formamidinium) or methylammonium (MA, methylammonium).

[0033] And X in Chemical Formula 1 is I - , Cl- or Br - and preferably, I - or Cl - , more preferably I - is.

[0034] (Chemical formula 2) BX2 B in chemical formula 2 is Fe 2+ , Co 2+ , Ni 2+ , Cu 2+ , Sn 2+ , Pb 2+ , Bi 2+ , Ge 2+ , Ti 2+ ,EU 2+ or Zr 2+ and preferably Cu 2+ , Sn 2+ , Pb 2+ , Bi 2+ , Ge 2+ or Ti 2+ and more preferably, Sn 2+ , Pb 2+ or Bi 2+ And, X in chemical formula 2 is I - , Cl - or Br - and preferably, I - or Cl - , more preferably I - is.

[0035] The solvent for the first step may include one or more selected from gamma-butyrolactone, gamma-valerolactone, alpha-angelica lactone, alpha-methylene-gamma-butyrolactone, alpha-hydroxy-gamma-butyrolactone, and caprolactone, preferably one or more selected from gamma-butyrolactone, gamma-valerolactone, and alpha-angelica lactone, and more preferably one or more selected from gamma-butyrolactone and gamma-valerolactone.

[0036] The mixed solution in one step may contain the organic anion precursor and the metal ion precursor in a molar ratio of 0.8 to 1.2: 1, preferably 0.9 to 1.2: 1, and more preferably 0.95 to 1.1: 1. In this case, if the molar ratio of the organic anion precursor to the metal ion precursor is less than 0.8 or exceeds 1.2, the yield of the perovskite crystal may be reduced.

[0037] The first step can be carried out at room temperature, 10 to 35°C, preferably 20 to 30°C. After adding the organic anion precursor and the metal ion precursor to a solvent, the mixture is stirred for about 1 to 2 hours, whereby the precursors are completely dissolved in the solvent, forming a transparent yellow reaction solution.

[0038] Next, in the two steps, the reaction solution in which the organic anion precursor and the metal ion precursor are dissolved in the first step is heated at 20 to 110°C, preferably 50 to 100°C, more preferably 50 to 80°C, and even more preferably 55 to 70°C, whereby the reaction solution becomes opaque or deep yellow.

[0039] When the anti-solvent is added dropwise, a yellow precipitate forms and the anti-solvent is added dropwise until the solution becomes colorless or transparent. In this case, it is preferable to use a benzene-based non-solvent rather than an ether-based non-solvent such as diethyl ether, methyl tert-butyl ether, or dimethyl ether, which has a low yield of about 30%.

[0040] If the temperature exceeds 110°C, the yield of delta-phase perovskite crystals will be too low due to an increase in alpha-phase perovskite crystals, while if the temperature is below 20°C, the amount of non-solvent used will be too large, the reaction time will be long, and the yield of delta-phase perovskite crystals will be low, which is uneconomical.

[0041] The amount of non-solvent added is preferably 200 to 400 volume ratios, more preferably 230 to 370 volume ratios, and more preferably about 260 to 340 volume ratios, per 100 volume ratio of the solvent used in one step.

[0042] The non-solvent may include one or more selected from chlorobenzene, toluene, and xylene, preferably one or more selected from chlorobenzene and toluene, and more preferably toluene.

[0043] In addition, before carrying out the following three steps, the drying step for removing the reaction solvent remaining in the precipitate obtained in the second step can be omitted.

[0044] Next, in the third step, the transparent and / or colorless solution is removed, and then the precipitate is primarily washed using a poor solvent. As the poor solvent, it is preferable to use a nitrile-based solvent that has a high boiling point and high volatility, and does not dissolve the perovskite crystals as the reaction product, but dissolves the organic anion precursors as the reaction residue, and has good miscibility with the solvent used in the first step.

[0045] The nitrile solvent may be at least one selected from acetonitrile, propionitrile, and aminopropionitrile, and preferably at least one selected from acetonitrile and propionitrile.

[0046] The three-stage primary washing is preferably repeated 1 to 3 times, preferably about 2 to 3 times.

[0047] Next, in step 4, the poor solvent used in step 3 is removed, followed by a second wash with an ether-based solvent and filtration to obtain a filtrate. The second wash is performed to remove the remaining solvent used in step 1 and the poor solvent used in the first wash.

[0048] The ether-based solvent used in the second cleaning may include at least one selected from diethyl ether, methyl tert-butyl ether, diisopropyl ether, and dibutyl ether, preferably at least one selected from diethyl ether, methyl tert-butyl ether, and dibutyl ether, and more preferably at least one selected from diethyl ether and methyl tert-butyl ether.

[0049] The filtration can be carried out by a common filtration method used in the art, and preferably by vacuum filtering.

[0050] From the viewpoint of improving the purity of the delta-phase perovskite crystal, it is preferable to repeat the washing and filtering in the four stages at least once, preferably 2 to 5 times, and more preferably about 3 to 5 times.

[0051] Next, in step 5, the filtered material is dried to obtain a yellow delta-phase perovskite crystal represented by Formula 3. The drying can be performed by a common method used in the art. As a preferred example, the filtered material obtained in step 4 can be stored in a vacuum oven for about 12 to 36 hours to be completely dried.

[0052] The delta-phase perovskite crystal synthesized by the method of the present invention may have a yield of 75.00% or more, preferably 82.00% or more, more preferably 90.00% or more, and even more preferably 93.0 to 99.0%, as measured according to the following formula 1.

[0053] [Formula 1] Yield (%) = (weight of obtained delta-phase perovskite crystals) / (weight of organic anion precursor used in the reaction + weight of metal ion precursor used in the reaction) × 100% The delta-phase perovskite crystal obtained by the synthesis method of the present invention can have a purity of 99.00% or more.

[0054] The delta-phase perovskite crystal prepared by this method can be used as a material in the electrical, electronic, or optical fields (solar cells, displays, lasers, sensors, etc.) where high electrical conductivity, charge mobility, and optical properties are required. As a preferred example, the delta-phase perovskite crystal can be used as a precursor to coat a perovskite layer that can be used as the light-absorbing layer (photoactive layer) of a solar cell, making it easier to control the light-absorbing layer with a targeted band gap. Therefore, it may be possible to efficiently control the indirect band gap.

[0055] A preferred example of a perovskite solar cell in which the delta-phase perovskite crystal produced by the method of the present invention is applied to the light absorption layer is as follows.

[0056] The perovskite solar cell can be a pin-structured perovskite solar cell, an inverted structured perovskite solar cell, a tandem perovskite solar cell or a tandem silicon / perovskite heterojunction solar cell.

[0057] A preferred embodiment of the perovskite solar cell is a solar cell including a laminate structure in which a hole transport layer (HTL), a perovskite light absorbing layer, an electron transporting layer (ETL), a conductive barrier layer (passivation layer), and a source electrode are laminated in this order.

[0058] In addition, when the solar cell is an inverted perovskite solar cell, the stack may be stacked on top of a drain electrode.

[0059] In addition, the inverted perovskite solar cell may be formed by stacking a conductive substrate, a drain electrode, a hole transport layer, a light absorption layer, an electron transport layer, and a source electrode in order to form one set, and the set may be stacked in a single layer or multiple layers.

[0060] In yet another preferred embodiment, when the solar cell of the present invention is a tandem silicon / perovskite heterojunction solar cell, a drain electrode, a silicon solar cell, a recombination layer, and the stack may be stacked in this order.

[0061] To explain in detail the method for manufacturing the laminate constituting the perovskite solar cell, the laminate can be manufactured by performing processes including: Step 1: forming an electron transport layer by coating a coating agent for forming an electron transport layer on the top of the perovskite light-absorbing layer of a laminate including a hole transport layer and a perovskite light-absorbing layer; Step 2: forming a passivation layer on the top of the electron transport layer through a deposition process; and Step 3: forming a source electrode on the top of the passivation layer.

[0062] The hole transport layer (HTL) may comprise inorganic and / or organic hole transport materials. The inorganic hole transport materials include nickel oxide (NiO x ), CuSCN, CuCrO2 and CuI.

[0063] The organic hole transport material may be a carbazole derivative, a polyarylalkane derivative, a phenylenediamine derivative, an arylamine derivative, an amino-substituted chalcone derivative, a styrylanthracene derivative, a fluorene derivative, a hydrazone derivative, a stilbene derivative, a silazane derivative, an aromatic tertiary amine compound, a styrylamine compound, an aromatic dimethylidine-based compound, a porphyrin-based compound, a phthalocyanine-based compound, a polythiophene derivative, a polypyrrole derivative, a polyparaphenylenevinylene derivative, pentacene, coumarin 6 (coumarin 6,3-(2-benzothiazolyl)-7-(diethylamino)coumarin), ZnPC (zinc phthalocyanine), CuPC (copper phthalocyanine), TiOPC (titanium oxide phthalocyanine), Spiro-MeOTAD(2,2',7,7'-tetrakis(N,Np-dimethoxyphenylamino)-9,9'-spirobifluorene), F16CuP C(copper(II)1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro-29H, 31H-phthalocyanine), SubPc(boron N3(cis-di(thiocyanato)-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)-ruthenium(II), P3HT(poly[3-hexylthiophene]), MDMO-PPV(poly[2-methoxy-5-(3',7'-dimethyloctyloxyl)]-1,4-phenylene vinylene)、MEH-PPV(poly[2-methoxy-5-(2’’-ethylhexyloxy)-p-phenylene vinylene])、P3OT(poly(3-octyl thiophene))、POT(poly(octyl thiophene))、P3DT(poly(3-decyl thiophene))、P3DDT(poly(3-dodecyl thiophene)、PPV(poly(p-phenylene vinylene))、TFB(poly(9,9’-dioctylfluorene-co-N-(4-butylphenyl)diphenyl amine)、ポリアニリン(Polyaniline)、Spiro-MeOTAD([2,22’,7,77’-tetrakis(N、N-di-pmethoxyphenyl amine)-9,9,9’-spirobi fluorine])、CuSCN、CuI、PCPDTBT(Poly[2,1,3-benzothiadiazole-4,7-diyl[4,4-bis(2-ethylhexyl-4H-cyclopenta[2,1-b:3,4-b’]dithiophene-2,6-diyl]]、Si-PCPDTBT(poly[(4,4’-bis(2-ethylhexyl)dithieno[3,2-b:2’,3’-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl])、PBDTTPD(poly((4,8-diethylhexyloxyl)、PFDTBT(poly[2,7-(9-(2-ethylhexyl)-9-hexyl-fluorene)-alt-5,5-(4’,7,-di-2-thienyl-2’,1’,3’-benzothiadiazole)])、PFO-DBT(poly[2,7-9,9-(dioctyl-fluorene)-alt-5,5-(4’,7’-di-2-thienyl-2’,1’,3’-benzothiadiazole)])、PSiFDTBT(poly[(2,7-dioctylsilafluorene)-2,7-diyl-alt-(4,7-bis(2-thienyl)-2,1,3-benzothiadiazole)-5,5'-diyl]), PCDTBT(Poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl]), PFB(poly(9,9'-dioctyl fluorene-co-bis(N,N'-(4,butylphenyl))bis(N,N'-phenyl-1,4-phenylene)diamine), F8BT(poly(9,9'-dioctylfluorene-cobenzothiadiazole), PEDOT(poly(3,4-ethylenedioxythiophene)), PEDOT:PSS The polymer may include poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate), PTAA (poly(triarylamine)), 2-PACz, and / or MeO-2PACz.

[0064] The hole transport layer can be formed by coating, vacuum deposition, or the like, and the coating method can be gravure coating, bar coating, printing, spraying, spin coating, dipping, or die coating.

[0065] Next, the light absorbing layer may include a delta phase perovskite crystal represented by Chemical Formula 3 above.

[0066] The electron transport layer may contain an inorganic material (e.g., a metal oxide) and / or an organic material. The electron transport layer may be a flat metal oxide layer, a metal oxide layer with a roughened surface, a composite metal oxide layer in which nanostructures (including metal oxide particles, nanowires, and / or nanotubes) of the same or different metal oxides are formed on the surface of a thin film of metal oxide, or a porous metal oxide layer. Preferably, the electron transport layer may contain a compact metal oxide layer or a meso-porous metal oxide layer. Preferred examples include TiO2, SnO2, ZnO, etc. The organic material may also include PCBM.

[0067] The upper electrode (or source electrode) of the solar cell can be formed by coating or depositing one or more materials selected from Pt, Au, Ni, Cu, Ag, In, Ru, Pd, Rh, Ir, Os, C, and conductive polymers.

[0068] The solar cell may further include a passivation layer between the light absorbing layer and the electron transport layer.

[0069] The present invention will be described in more detail below with reference to examples. However, it should be understood that the following examples do not limit the scope of the present invention, but are merely intended to aid in the understanding of the present invention.

[0070] [Example] Example 1: Synthesis of delta-phase perovskite crystals A lactone solvent, gamma-butyrolactone, was added to an Erlenmeyer flask, and then an organic anion precursor represented by the following Chemical Formula 1-1 and a metal ion precursor represented by the following Chemical Formula 2-1 were added and dissolved to prepare a transparent yellow reaction solution.

[0071] In this case, the mixing molar ratio of the organic anion precursor and the metal ion precursor was 1:1.

[0072] Next, the reaction solution was heated to about 25° C., and the reaction solution became cloudy and changed to an opaque yellow color. Toluene as a non-solvent was added dropwise to the reaction solution while stirring.

[0073] The addition of the non-solvent resulted in the formation of a precipitate, and the dropwise addition of toluene as a non-solvent was continued until the reaction solution became colorless (or transparent). At this time, the amount of the non-solvent added was approximately three times the volume ratio of the amount of gamma-butyrolactone used.

[0074] Next, after removing the colorless (or transparent) reaction solution, the precipitate was washed three times by adding acetonitrile as a poor solvent. After adding the poor solvent, the solvent turned cloudy, but it was continued until it became transparent, and then the solvent was discarded and removed.

[0075] Next, the precipitate after the first washing was washed with diethyl ether and filtered under reduced pressure to obtain a filtrate, and the washing and filtration were repeated twice.

[0076] The filtered material was then stored in a vacuum oven for 24 hours to completely dry it, yielding a delta-phase perovskite crystal represented by the following formula 3-1 (yield 91.2%, purity 99.90-99.95%).

[0077] Photographs of the manufacturing process are shown in Figure 1.

[0078] (Chemical formula 1-1) AX

[0079] (Chemical formula 2-1) BX2

[0080] (Chemical formula 3-1) ABX3 In the above Chemical Formula 1-1 and Chemical Formula 3-1, A is formamidinium (FA), and in the Chemical Formula 1-1, Chemical Formula 2-1, and Chemical Formula 3-1, B is Pb 2+and X is I - is.

[0081] Examples 2 to 3 and Comparative Examples 1 to 3 Examples 2 to 3 and Comparative Examples 1 to 3 were carried out by producing perovskite crystals in the same manner as in Example 1, but by varying the temperature of the reaction solution when toluene was added as a non-solvent to the reaction solution, as shown in Table 1 below, to produce perovskite crystals.

[0082] Example 4 A perovskite crystal was produced in the same manner as in Example 2, but chlorobenzene was used as the non-solvent instead of toluene to produce a delta-phase perovskite crystal.

[0083] Example 5 Perovskite crystals were produced in the same manner as in Example 2, but xylene was used as the non-solvent instead of toluene to produce delta-phase perovskite crystals.

[0084] Comparative Example 4 A perovskite crystal was produced in the same manner as in Example 1, but diethyl ether as an ether solvent was used instead of toluene as a non-solvent to produce a delta-phase perovskite crystal.

[0085] [Table 1]

[0086] Experimental Example 1: XRD and TGA measurements (1)XRD measurement The results of XRD measurement of the delta-phase perovskite crystals produced in Examples 1 to 3 and Comparative Examples 1 to 3 are shown in FIG.

[0087] Referring to FIG. 2, it can be seen that the phase of the delta-phase perovskite crystal (powder) obtained (synthesized) represented by Chemical Formula 3-1 changes as the temperature of the solvent (gamma-butyrolactone) in which the organic anion precursor and metal ion precursor are dissolved changes.

[0088] Below 90°C, the majority of the synthesized perovskite crystals are obtained as delta phase, while in the range of about 110-150°C, a mixture of alpha and delta phases is obtained, and in the range of 150-180°C, it can be confirmed that the majority is obtained as alpha phase.

[0089] (2)TGA measurement The results of TGA measurement of the delta-phase perovskite crystal produced in Example 2 are shown in FIG. 3, and it was confirmed that the delta-phase perovskite crystal was of high purity.

[0090] Experimental Example 2: Yield Measurement The synthesis yields of the delta-phase perovskites produced in Examples 1 to 5 and Comparative Examples 1 to 4 were determined based on the following formula 1, and the results are shown in Table 2 below.

[0091] Figure 2 shows the XRD measurement results as a function of temperature.

[0092] [Formula 1] Delta-phase perovskite yield (%) = (weight of obtained delta-phase perovskite crystals) / (weight of organic anion precursor used in the reaction + weight of metal ion precursor used in the reaction) × 100%

[0093] [Table 2]

[0094] Referring to Table 2, in Examples 1 to 5, in which organic anion precursors and metal ion precursors were synthesized at temperatures below 90° C., delta-phase perovskite was mostly obtained in the total perovskite yield. In addition, in Example 4, in which chlorobenzene was used as the non-solvent, and Example 5, in which xylene was used, the total perovskite yield tended to be slightly lower than in Example 2, in which toluene was used as the non-solvent.

[0095] Furthermore, Example 2 synthesized at 60°C tended to have a higher overall perovskite yield than Example 1 synthesized at 25°C, while Example 3 synthesized at 90°C tended to have a relatively lower overall perovskite yield than Example 2.

[0096] In Comparative Examples 1 to 3, in which organic anion precursors and metal ion precursors were synthesized at 120 to 180°C, the overall yield of perovskite was high. However, Comparative Example 1 showed a significantly lower yield of delta-phase perovskite compared to Example 3, and Comparative Examples 2 and 3 showed that most of the perovskite was alpha-phase.

[0097] Furthermore, in the case of Comparative Example 4, in which diethyl ether was used as the non-solvent, the overall yield of perovskite was lower than in Example 2, and the yield of the delta phase was also relatively low.

[0098] Through this, it was confirmed that the optimum temperature range for the organic anion precursor and metal ion precursor is 40 to 90°C, preferably approximately 50 to 80°C, from the viewpoints of the total yield of perovskite and delta phase, productivity, and economy.

[0099] Manufacturing Example 1: Manufacturing of Perovskite Solar Cells The delta-phase perovskite crystals prepared in Example 2, CsBr, and PbBr2 were dissolved in DMF (Dimethylformamide) and NMP (N-Methyl-2-Pyrrolidinone) to prepare a coating agent for forming a perovskite thin film, and then used to prepare (FAPbI3). 0.8 (CsPbBr3) 0.2A single opaque perovskite solar cell (active area: 0.096 cm) was fabricated. 2 Specifically, the structure of the opaque single element is an organic substrate on which ITO (100 nm) is deposited, followed by NiO x (17 nm), 2PACz (1 nm), perovskite thin film ((FAPbI3) 0.8 (CsPbBr3) 0.2 , 550nm), LiF (1nm), C60 (13nm), BCP (8nm), Ag electrode (200nm).

[0100] Manufacturing Examples 2-3 Perovskite solar cells were manufactured in the same manner as in Manufacturing Example 1, but the perovskite crystals manufactured in Examples 4 and 5 were used instead of Example 2 to manufacture solar cells, thereby carrying out Manufacturing Examples 2 and 3, respectively.

[0101] Comparative Manufacturing Example 1 FAI, PbI2, CsBr, and PbBr2 were dissolved in DMF (Dimethylformamide) and NMP (N-Methyl-2-Pyrrolidinone) to prepare a coating agent (precursor solution) for forming perovskite thin films, and then this was used to prepare (FAPbI3). 0.8 (CsPbBr3) 0.2 A single opaque perovskite solar cell (active area: 0.096 cm) was fabricated. 2 Specifically, the structure of the opaque single element is an organic substrate on which ITO (100 nm) is deposited, followed by NiOx (17 nm), 2PACz (1 nm), and a perovskite thin film ((FAPbI3) 0.8 (CsPbBr3) 0.2 , 550nm), LiF (1nm), C60 (13nm), BCP (8nm), Ag electrode (200nm).

[0102] Experimental example 2: Performance measurement of solar cell elements The current-voltage characteristics and efficiency of the solar cells produced in Production Examples 1 to 3 were measured, and the results are shown in Table 3 below and FIG.

[0103] [Table 3]

[0104] Referring to Table 3 and FIG. 4, it can be seen that Preparation Examples 1 to 3 all have relatively higher photoelectric conversion efficiencies than Comparative Preparation Example 1, and in particular, Preparation Example 1 has about 2% higher photoelectric conversion efficiency than Comparative Preparation Example 1.

[0105] Through the above examples and experimental examples, it has been confirmed that delta-phase perovskite crystals can be produced in high yields while using fewer chemicals than conventional synthesis methods, and that when this is applied to a light absorption layer material, it can provide perovskite solar cells with excellent efficiency.

Claims

1. a step of preparing a reaction solution by adding a solvent to a reactor and then adding and dissolving an organic anion precursor represented by the following Chemical Formula 1 and a metal ion precursor represented by the following Chemical Formula 2 in the solvent; The reaction solution is heated at 20 to 110°C, and when the reaction solution turns yellow, an anti-solvent is added to obtain a solution containing a precipitate; Step 3: After removing the colorless solution from the solution containing the precipitate of Step 2, the precipitate is first washed with a bad solvent; a fourth step of subjecting the precipitate obtained after the first washing to a second washing with an ether-based solvent and filtering the precipitate to obtain a filtrate; and and drying the filtered material to obtain a delta-phase perovskite crystal represented by the following chemical formula 3: (Chemical formula 1) AX (Chemical formula 2) BX ２ (Chemical formula 3) ABX ３ In the formulas 1 and 3, A is formamidinium (FA), methylammonium (MA), FA ｘ MA （１－ｘ） (0<X<1), or N(R １ ) ４ ＋ and R １ represents a linear alkyl group having 1 to 5 carbon atoms, a branched alkyl group having 3 to 5 carbon atoms, a phenyl group, an alkylphenyl group, or an alkoxyphenyl group, In the formulas 2 and 3, B is Fe. ２＋ , Co ２＋ , Ni ２＋ , Cu ２＋ , Sn ２＋ , Pb ２＋ , Bi ２＋ , Ge ２＋ , Ti ２＋ , Eu ２＋ or Zr ２＋ and X is I － , Cl － or Br － is.

2. 2. The method for producing a delta-phase perovskite crystal according to claim 1, wherein the solvent in the first step comprises at least one selected from the group consisting of gamma-butyrolactone, gamma-valerolactone, alpha-angelica lactone, alpha-methylene-gamma-butyrolactone, alpha-hydroxy-gamma-butyrolactone, and caprolactone.

3. 2. The method for producing a delta-phase perovskite crystal according to claim 1, wherein the reaction solution in one step contains the organic anion precursor and the metal ion precursor in a molar ratio of 0.8 to 1.2:

1.

4. 2. The method for producing a delta-phase perovskite crystal according to claim 1, wherein the non-solvent comprises at least one selected from the group consisting of chlorobenzene, toluene, and xylene.

5. 2. The method for producing a delta-phase perovskite crystal according to claim 1, wherein the amount of non-solvent added in the second stage is 200 to 400 by volume relative to 100 by volume of the solvent used in the first stage.

6. The poor solvent may be a nitrile solvent including at least one selected from the group consisting of acetonitrile, propionitrile, and aminopropionitrile; 2. The method for producing a delta-phase perovskite crystal according to claim 1, wherein the ether-based solvent comprises at least one selected from the group consisting of diethyl ether, methyl tert-butyl ether, diisopropyl ether, and dibutyl ether.

7. 2. The method for producing delta-phase perovskite crystals according to claim 1, wherein the delta-phase perovskite crystals obtained through the five steps have a yield of 75% or more and a purity of 99% or more.

8. A delta-phase perovskite crystalline body produced by the method of any one of claims 1 to 7, A delta-phase perovskite crystal characterized by being a perovskite crystal represented by the following chemical formula 3: (Chemical formula 3) ABX ３ In the formula 3, A is formamidinium (FA), methylammonium (MA), FA ｘ MA （１－ｘ） (0<X<1), or N(R １ ) ４ ＋ and R １ is a linear alkyl group having 1 to 5 carbon atoms, a branched alkyl group having 3 to 5 carbon atoms, a phenyl group, an alkylphenyl group or an alkoxyphenyl group, and B is Fe ２＋ , Co ２＋ , Ni ２＋ , Cu ２＋ , Sn ２＋ , Pb ２＋ , Bi ２＋ , Ge ２＋ , Ti ２＋ , Eu ２＋ or Zr ２＋ and X is I － , Cl － or Br － is.

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