Method for synthesizing delta-phase perovskite crystal, and delta-phase perovskite crystal produced thereby

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 at high yield and to a delta-phase perovskite crystal produced using same.

Description

Delta-phase perovskite crystal synthesis method and delta-phase perovskite crystal manufactured by the method

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

[0002] To address the depletion of fossil fuels and the global environmental problems caused by their use, research is actively being conducted on 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, is growing significantly. Here, a solar cell refers to a cell that generates current and voltage by utilizing the photovoltaic effect, which generates electrons and holes by absorbing light energy from sunlight.

[0004]

[0005] *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 these are actually being used for solar power generation. There are also solar cells using compound semiconductors such as gallium arsenide (GaAs) with even better conversion efficiencies. However, these inorganic semiconductor-based solar cells require highly purified materials to achieve high efficiency, so a lot of energy is consumed in refining the raw materials. In addition, expensive processing equipment is required in the process of forming single crystals or thin films using the raw materials, which limits the cost of manufacturing solar cells, and this has been an obstacle to large-scale utilization.

[0006] Accordingly, in order to manufacture solar cells at low cost, it is necessary to drastically reduce the cost of materials or manufacturing processes used as core components of solar cells, and research is being conducted on perovskite solar cells that can be manufactured using low-cost materials and processes as an alternative to inorganic semiconductor-based solar cells.

[0007] The general structural formula of the perovskite structure is the AMX3 structure, in which an anion is located at the X site, a large cation is located at the A site, and a small cation is located at the M site.

[0008] These perovskite compounds have a wide range of applications due to their excellent electrical conductivity, charge mobility, and optical properties, and have various characteristics including long life, high absorption wavelength spectra due to small energy band gaps, and wide charge-carrier diffusion lengths. In addition, they have the advantages of being economical in material cost, can be produced in solution, have low process costs, and can be manufactured using low-temperature processes, and are attracting attention as promising materials for renewable energy applications. In particular, research is ongoing to use them as light absorbers for perovskite solar cells.

[0009] To create high-efficiency solar cells, fabricating high-quality perovskite thin films using high-purity materials is crucial for achieving high solar cell efficiency. This is directly related to the purity of the starting materials used in perovskite synthesis. Furthermore, the stoichiometry of the precursor materials used is also a crucial factor.

[0010] The conventional synthetic method for producing perovskite crystals with the structure of ABX3 (A = monovalent organic cation, B = divalent metal cation, X = halogen ion) is to synthesize ABX3 from AX and BX2 at high temperature in a solvent, and then filter and dry it to obtain it. However, the synthetic yield is low, which reduces mass productivity. In addition, unwanted by-products are generated during the synthesis of AX, a precursor used in the synthesis, which limits the low yield. Therefore, attempts and research are ongoing to synthesize high-quality perovskite with a high yield to provide economically viable perovskite.

[0011] The present invention has been devised to overcome the above-described problems, and provides a method for efficiently manufacturing a delta-phase perovskite composite with a high yield and / or high purity while enabling mass production, and a delta-phase perovskite composite manufactured by the method.

[0012] In order to solve the above-described problem, the present invention relates to a method for preparing a delta-phase perovskite crystal, comprising: a first step of preparing a reaction solution by introducing a solvent into a reactor, and then 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; a second step of heat-treating the reaction solution at 150 to 170°C for 30 minutes to 3 hours to obtain a solution containing a precipitate; a third step of filtering the solution containing the precipitate of the second step to obtain the precipitate from the solution, and then washing the precipitate with a bad solvent; a fourth step of purifying the precipitate washed in the third step with an ether solvent and then filtering it to obtain a filtrate; and a fifth step of drying the filtrate to obtain a delta-phase perovskite crystal represented by the following chemical formula 3.

[0013] [Chemical Formula 1]

[0014] AX

[0015] [Chemical Formula 2]

[0016] BX2

[0017] [Chemical Formula 3]

[0018] ABX3

[0019] In the above chemical formulas 1 and 3, A is formamidinium (FA), methylammonium (MA), FA x MA (1-x) (0 <X<1), 또는 N(R 1 )4 + and R 1is a straight-chain 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 chemical 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 - am.

[0020] In a preferred embodiment of the present invention, the solvent of step 1 may include at least one selected from gamma-butyrolactone, gamma-valerolactone, α-angelica lactone, α-methylene-γ-butyrolactone, α-hydroxy-γ-butyrolactone, and ε-caprolactone.

[0021] As a preferred embodiment of the present invention, in step 1, the reaction solution may contain a precursor including an organic anion precursor and a metal ion precursor at a concentration of 1.5 to 2.8 M.

[0022] As a preferred embodiment of the present invention, in step 1, the reaction solution may contain the organic anion precursor and the metal ion precursor in a molar ratio of 1:0.9 to 1.25.

[0023] As a preferred embodiment of the present invention, the poor solvent may include a nitrile solvent including at least one selected from acetonitrile, propionitrile, and aminopropionitrile.

[0024] As a preferred embodiment of the present invention, the ether solvent is an acyclic ether solvent and may include at least one selected from diethyl ether, tert-butyl ethyl ether, diisopropyl ether, and dibutyl ether.

[0025] As a preferred embodiment of the present invention, the perovskite compound in the filtrate of the fourth step may include 99.0% or more of an alpha-phase perovskite compound.

[0026] As a preferred embodiment of the present invention, the delta-phase perovskite crystal obtained in step 5 may have a yield of 40.00% or more and a purity of 99.00% or more, preferably a yield of 50.00% or more and a purity of 99.00% or more, and more preferably a yield of 60.00% or more and a purity of 99.00% or more.

[0027] Another object of the present invention is a delta-phase perovskite crystal manufactured by the method described above, wherein the perovskite complex may be a perovskite crystal represented by the following chemical formula 3.

[0028] [Chemical Formula 3]

[0029] ABX3

[0030] In the above chemical formula 3, A is formamidinium (FA), methylammonium (MA. methylammonium), FA x MA (1-x) (0 <X<1), 또는 N(R 1 )4+ and R 1 is a straight-chain 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 - am.

[0031] In addition, another object of the present invention is to provide a perovskite crystal as a light-absorbing layer (or photoactive layer) and a perovskite solar cell including the same.

[0032] The present invention enables mass production of delta-phase perovskite crystals with high yield and high purity in an economical manner, regardless of the purity or quality of a precursor used in manufacturing the perovskite crystals, and the delta-phase perovskite crystals of the present invention can be applied as materials in electrical, electronic or optical fields requiring high electrical conductivity, charge mobility and optical properties, and as a preferred example, the delta-phase perovskite crystals can be applied as a light-absorbing layer (photoactive layer) of a solar cell.

[0033] Figure 1 is an image showing a schematic process for synthesizing a delta-phase perovskite crystal performed in Example 1.

[0034] Figure 2 is a photograph of the pre-drying filtrate (a) and the delta-phase perovskite crystal (b) obtained by drying during the crystal synthesis of Examples 6 to 10.

[0035] Figure 3 is a photograph of the pre-drying filtrate (a) and the delta-phase perovskite crystal (b) obtained by drying during the crystal synthesis of Examples 11 to 15.

[0036] Figure 4 is a photograph of the pre-drying filtrate (a) and the delta-phase perovskite crystal (b) obtained by drying during the crystal synthesis of Examples 16 to 20.

[0037] Figures 5 and 6 are graphs showing the yield and XRD measurement of delta-phase perovskite crystals obtained in Experimental Example 1.

[0038] Figure 7 shows the results of UV-vis spectroscopy measurements conducted in Experimental Example 3.

[0039] Figure 8 shows the results of X-ray diffraction measurements conducted in Experimental Example 3.

[0040] Figure 9 shows the results of photoluminescence measurement conducted in Experimental Example 3.

[0041] Figure 10 shows the performance measurement results of solar cell elements of manufacturing examples 1 to 4 conducted in experimental example 4.

[0042] Figure 11 shows the performance measurement results of solar cell elements of Manufacturing Example 2 and Manufacturing Examples 5 to 7 conducted in Experimental Example 4.

[0043] Figure 12 shows the performance measurement results of the solar cell elements of Manufacturing Example 8 and Comparative Manufacturing Example 2 conducted in Experimental Example 4.

[0044] Hereinafter, the present invention will be described in more detail.

[0045] The present invention relates to a method for producing a perovskite crystal, which is a compound represented by the following chemical formula 3.

[0046] [Chemical Formula 3]

[0047] ABX3

[0048] In the above chemical formula 3, A is formamidinium (FA), methylammonium (MA. methylammonium), FA x MA(1-x) (0 <X<1), 또는 N(R 1 )4 + and preferably formamidinium (FA), methylammonium (MA) or FA x MA (1-x) (0 <X<1)이며, 더욱 바람직하게는 포름아미디늄(FA, formamidinium) 또는 메틸암모늄(MA. methylammonium)이다. 그리고, 상기 R 1 is a straight-chain 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 R 1 is a straight-chain alkyl group having 1 to 5 carbon atoms, and more preferably a straight-chain alkyl group having 1 to 2 carbon atoms.

[0049] 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+ or Zr 2+ , 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 more preferably Pb 2+ am.

[0050] And, X in chemical formula 3 is I - , Cl - or Br - and preferably I - or Cl - , more preferably I - am.

[0051]

[0052] Organic halides such as formamidinium iodide (FAI) are vulnerable to moisture, purified organic halides are expensive, and direct synthesis of organic halides during perovskite (ABX3) synthesis is very uneconomical considering the low yield of conventional perovskite synthesis methods.

[0053] The delta-phase perovskite crystal of the present invention can be synthesized by performing a process including the following steps: 1) introducing a solvent into a reactor, and then 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 prepare a reaction solution; 2) heat-treating the reaction solution at 150 to 170°C for 30 minutes to 3 hours to obtain a solution containing a precipitate; 3) filtering the solution containing the precipitate of the 2nd step to obtain a precipitate from the solution, and then washing the precipitate with a bad solvent; 4) purifying the precipitate that has undergone the 3rd step with an ether solvent, and then filtering to obtain a filtrate; and 5) drying the filtrate to obtain a delta-phase perovskite crystal represented by the above chemical formula 3.

[0054] [Chemical Formula 1]

[0055] AX

[0056] In chemical formula 1, A is formamidinium (FA), methylammonium (MA), FA x MA (1-x) (0 <X<1), 또는 N(R 1 )4 + and preferably formamidinium (FA), methylammonium (MA) or FA x MA (1-x)(0 <X<1)이며, 더욱 바람직하게는 포름아미디늄(FA, formamidinium) 또는 메틸암모늄(MA. methylammonium)이다.

[0057] And, X in chemical formula 1 is I - , Cl - or Br - and preferably I - or Cl - , more preferably I - am.

[0058] [Chemical Formula 2]

[0059] BX2

[0060] 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+ , 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 - am.

[0061] The solvent of the above step 1 may include at least one selected from among gamma-butyrolactone, gamma-valerolactone, α-angelica lactone, α-methylene-γ-butyrolactone, α-hydroxy-γ-butyrolactone, and ε-caprolactone, preferably at least one selected from among gamma-butyrolactone, gamma-valerolactone, and α-angelica lactone, and more preferably at least one selected from among gamma-butyrolactone and gamma-valerolactone.

[0062] The above reaction solution of step 1 may contain a precursor including an organic anion precursor and a metal ion precursor at a concentration of 1.5 to 2.8 M, preferably at a concentration of 1.8 to 2.6 M, and more preferably at a concentration of 1.95 to 2.45 M. At this time, if the concentration of the precursor in the reaction solution is less than 1.5 M, there may be a problem that the yield of the perovskite crystal to be synthesized is too low, and since the metal ion precursor has low solubility in the solvent, it may be difficult to prepare the reaction solution so that the concentration exceeds 2.8 M. Therefore, it is appropriate to use a reaction solution having a concentration within the above range in terms of the ease of the manufacturing process and the yield of the perovskite crystal.

[0063] And, the mixed solution of step 1 may contain the organic anion precursor and the metal ion precursor in a molar ratio of 1:0.90 to 1.25, preferably the organic anion precursor and the metal ion precursor in a molar ratio of 1:0.90 to 1.15, more preferably 1:0.95 to 1.10. At this time, if the molar ratio of the metal ion precursor is less than 0.90 molar ratio or exceeds 1.25 molar ratio based on the organic anion precursor, there may be a problem that the yield of the perovskite crystal is lowered.

[0064] Step 1 can be performed at room temperature conditions of 10 to 35°C, preferably 20 to 30°C, and after adding the organic anion precursor and the metal ion precursor to a solvent and stirring for about 1 to 2 hours, they are completely dissolved in the solvent to form a transparent yellow reaction solution.

[0065] Next, in the second step, the reaction solution in which the organic anion precursor and the metal ion precursor are dissolved in the first step is heat-treated at 150 to 170°C, preferably 155 to 170°C, for 30 minutes to 3 hours, preferably 1 hour to 2 hours and 30 minutes.

[0066] At this time, if the heating temperature exceeds 170°C, there may be a problem that the reaction product crystals, i.e., precipitates, are re-dissolved in the solution, and if it is lower than 150°C, the reaction time may be prolonged, and the production of precipitates may be small, which may result in a problem that the overall yield of delta-phase perovskite crystals may be reduced.

[0067] In addition, the drying process for removing the reaction solvent remaining in the precipitate obtained in step 2 before performing step 3 below can be omitted.

[0068]

[0069] Next, the third step is a process of filtering a solution containing a precipitate to obtain a precipitate from the solution, and then washing the precipitate using a bad solvent. As the bad solvent, it is preferable to use a nitrile-based solvent that has a boiling point and high volatility, does not dissolve the perovskite crystal, which is a reaction product, but dissolves organic anion precursors, which are reaction residues, well, and has good miscibility with the solvent of the first step.

[0070] As the above nitrile solvent, at least one selected from acetonitrile, propionitrile, and aminopropionitrile can be used, and preferably at least one selected from acetonitrile and propionitrile can be used.

[0071] And, it is recommended that the above three-step washing be repeated 1 to 7 times, preferably 3 to 6 times.

[0072]

[0073] Next, step 4 is a process of removing the solvent used for washing in step 3, purifying the product with an ether solvent, and then filtering to obtain a filtrate. The purification process is performed to remove any remaining solvent used in step 1 and the solvent used for washing.

[0074] The ether solvent used in the purification treatment may include at least one selected from diethyl ether, tert-butyl ethyl ether, diisopropyl ether, and dibutyl ether, preferably at least one selected from diethyl ether, tert-butyl ethyl ether, and dibutyl ether, and more preferably at least one selected from diethyl ether and tert-butyl ethyl ether.

[0075] In addition, the above filtration can be performed through a general filtration method used in the art, and preferably, the filtration can be performed by performing pressure reduction filtration.

[0076] In addition, it is preferable to repeat the above 4-step purification and filtration at least once, preferably 2 to 5 times, and preferably 3 to 5 times, in order to improve the purity of the delta-phase perovskite crystal.

[0077] The perovskite compound in the filtrate obtained in step 4 may contain an alpha-phase perovskite compound in an amount of 99.0% or more, preferably 99.50% or more, and more preferably 99.99% or more.

[0078] Next, step 5 is a process of drying the filtrate to obtain a delta-phase perovskite crystal represented by the chemical formula 3. The drying can be performed using a general method used in the art, and as a preferred example, the filtrate obtained in step 4 can be completely dried by storing it in a vacuum oven for 12 to 36 hours. When the drying is performed, the alpha-phase perovskite compound of the filtrate (black) is converted into a delta-phase perovskite compound, i.e., a crystal (yellow).

[0079] The delta-phase perovskite crystal obtained by synthesis using the method of the present invention described above may have a yield of 40.00% or more, preferably 50.00% or more, and more preferably 60.00% or more, as measured according to the following equation 1.

[0080] [Formula 1]

[0081] 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%

[0082] The delta-phase perovskite crystal obtained by synthesis using the method of the present invention described above can have a purity of 99.00% or more.

[0083] The delta-phase perovskite crystals manufactured by the above method can be applied as materials in electrical, electronic or optical fields (solar cells, displays, lasers, sensors, etc.) that require high electrical conductivity, charge mobility and optical properties. As a preferred example, the delta-phase perovskite crystals can be used as a precursor to coat a perovskite layer that can be used as a light-absorbing layer (photoactive layer) of a solar cell, and the light-absorbing layer having a target band gap can be more easily controlled. Therefore, the indirect band gap can be efficiently controlled.

[0084] A preferred example of a perovskite solar cell using a delta-phase perovskite crystal manufactured by the method of the present invention as a light-absorbing layer is as follows.

[0085] The above perovskite solar cell may be a pin-type perovskite solar cell, an inverted-type perovskite solar cell, a tandem-type perovskite solar cell, or a tandem-type silicon / perovskite heterojunction solar cell.

[0086] A preferred embodiment of a perovskite solar cell is a solar cell including a laminated structure in which a hole transport layer (HTL, or hole transport layer), a perovskite light-absorbing layer, an electron transporting layer (ETL), a passivation layer, and a source electrode are sequentially laminated.

[0087] Additionally, if the solar cell is an inverse structure perovskite solar cell, the laminate may be laminated on top of a drain electrode.

[0088] In addition, the above-described inverse structure perovskite solar cell comprises a set in which a conductive substrate, a drain electrode, a hole transport layer, a light absorption layer, an electron transport layer, and a source electrode are sequentially laminated, and the set may be formed by laminating a single layer or multiple layers.

[0089] As 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 laminated body may be sequentially laminated.

[0090] Hereinafter, a method for manufacturing the laminate constituting the perovskite solar cell will be described in detail. The laminate can be manufactured by performing a process including: a first step of forming an electron transport layer by coating a coating agent for forming an electron transport layer on the perovskite light-absorbing layer of the laminate including a hole transport layer and a perovskite light-absorbing layer; a second step of forming a passivation layer on the electron transport layer through a deposition process; and a third step of forming a source electrode on the passivation layer.

[0091] The above hole transport layer (HTL) may include an inorganic and / or organic hole transport material. The inorganic hole transport material may be nickel oxide (NiO x ), may include at least one selected from CuSCN, CuCrO2, and CuI.

[0092] The above organic hole transport material is selected from the group consisting of carbazole derivatives, polyarylalkane derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorene derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidine compounds, porphyrin compounds, phthalocyanine compounds, polythiophene derivatives, polypyrrole derivatives, polyparaphenylenevinylene derivatives, 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), F16CuPC(copper(II) 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro-29H,31H-phthalocyanine), SubPc (boron subphthalocyanine chloride) and 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), 폴리아닐린(Polyaniline), Spiro-MeOTAD([2,22′,7,77′-tetrkis(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′-dioctylfluorene-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)), It may include PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)), PTAA (poly(triarylamine)), 2-PACz, and / or MeO-2PACz.

[0093] And, as a method for forming the hole transport layer, examples thereof include a coating method and a vacuum deposition method, and as a coating method, examples thereof include a gravure coating method, a bar coating method, a printing method, a spray method, a spin coating method, a dip method, and a die coat method.

[0094]

[0095] Next, the light absorbing layer may include a delta-phase perovskite crystal represented by the chemical formula 3 described above.

[0096]

[0097] Next, the electron transport layer may include 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 having a surface roughness, a composite metal oxide layer in which nanostructures of the same or different metal oxides (including metal oxide particles, nanowires and / or nanotubes) are formed on the surface of a metal oxide in a thin film shape, or a porous metal oxide layer. Preferably, the electron transport layer may include a compact metal oxide layer and a meso-porous metal oxide layer, and preferred examples thereof include TiO2, SnO2, ZnO, etc. In addition, the organic material may include PCBM.

[0098] And, among the solar cell configurations, the upper electrode (or source electrode) can be formed by coating or depositing one or more materials selected from among Pt, Au, Ni, Cu, Ag, In, Ru, Pd, Rh, Ir, Os, C, and conductive polymers.

[0099] Additionally, the solar cell may further include a passivation layer between the light absorption layer and the electron transport layer.

[0100]

[0101] Hereinafter, the present invention will be described in more detail through examples, but the following examples do not limit the scope of the present invention, and should be interpreted as helping to understand the present invention.

[0102] [Example]

[0103] Example 1: Synthesis of delta-phase perovskite crystals

[0104] Delta-phase perovskite crystals were synthesized using the following method (see Fig. 1).

[0105] After adding γ-butyrolactone, a lactone solvent, to a triangular flask, 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, stirred at 25°C, and dissolved to prepare a transparent yellow reaction solution.

[0106] At this time, the molar ratio of the organic anion precursor and the metal ion precursor was 1:0.9. And, the concentration of the precursors (organic anion precursor and metal ion precursor) in the reaction solution was 1.6 M.

[0107] Next, the above reaction solution was heat-treated at 160°C for 2 hours, and crystals were formed 5 minutes after the heat treatment.

[0108] After the heat treatment was completed, the precipitate was obtained by filtering to remove unreacted substances and solutions. The precipitate was poured into a flask containing acetonitrile, a bad solvent, and stirred to wash and filter under reduced pressure. This washing process was repeated five times. Discoloration of the bad solvent was observed with each washing. The washing solvent was green in the first washing, yellow in the second washing, gradually becoming lighter from the third washing, and colorless in the fifth washing.

[0109] Next, the precipitate after washing was washed with diethyl ether, a purification solvent, and filtered through a pressure filtration to obtain a black filtrate. The washing and filtration were repeated three times. The purification solvent was red during the first purification, but was colorless from the second purification onwards.

[0110] And, the above filtrate is a black crystal and is an alpha-phase perovskite compound with a purity of almost 99.99%.

[0111] Next, the filtrate was stored in a vacuum oven at 25°C for 24 hours to completely dry the filtrate, thereby obtaining a delta-phase perovskite crystal represented by the following chemical formula 3-1 (yield 36.0%, purity 99.90-99.95%).

[0112] [Chemical Formula 1-1]

[0113] AX

[0114] [Chemical Formula 2-1]

[0115] BX2

[0116] [Chemical Formula 3-1]

[0117] ABX3

[0118] In the above chemical formulas 1-1 and 3-1, A is formamidinium (FA), and in chemical formulas 1-1, 2-1 and 3-1, B is Pb 2+ and X is I - am.

[0119]

[0120] Examples 2 to 35

[0121] Delta-phase perovskite crystals were manufactured using the same method as in Example 1, but the molar ratio of the organic anion precursor and the metal ion precursor in the reaction solution and the concentration of the precursors (organic anion precursor and metal ion precursor) in the reaction solution were changed as shown in Table 1 below, and thus perovskite crystals were manufactured, respectively, and Examples 2 to 35 were performed.

[0122] The photographs of the filtrates (black crystals) of Examples 6 to 20 obtained by varying the concentration of precursors in the reaction solution and preparing the organic anion precursor and metal ion precursor at molar ratios of 1:10, 1:1.1, and 1.25, and the delta-phase perovskite crystals obtained by drying them are shown in FIG. 2 (1:10 molar ratio), FIG. 3 (1:1.11 molar ratio), and FIG. 4 (1:1.25 molar ratio).

[0123] Molar ratio of organic anion precursor and metal ion precursor Precursor concentration in reaction solution Heat treatment temperature / time Example 11: 0.9 1.54 M 160℃ / 2.5 hours Example 21.68 M Example 31.85 M Example 42.06 M Example 52.23 M Example 61: 1.0 1.66 M Example 71.81 M Example 82.00 M Example 92.22 M Example 102.40 M Example 111: 1.1 1.78 M Example 121.95 M Example 132.14 M Example 142.38 M Example 152.58 M Example 161: 1.25 1.97 M Example 172.14 M Example 182.36 M Example 192.62 M Example 202.84 M Example 210.9 : 11.62 M Example 221.76 M Example 231.94 M Example 242.16 M Example 252.34 M Example 261.1 : 11.71 M Example 271.86 M Example 282.05 M Example 292.28 M Example 302.47 M Example 311.25 : 11.77 M Example 321.94 M Example 332.13 M Example 342.37 M Example 352.57 M

[0124]

[0125] Experimental Example 1: Yield and XRD Measurement

[0126] (1) Measurement of yield

[0127] The synthesis yields of the delta-phase perovskites manufactured in Examples 1 to 35 were measured according to Equation 1 below, and the results are shown in Table 2 below. The yield graphs are shown in Figures 5 and 6.

[0128] [Formula 1]

[0129] 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%

[0130] (2) XRD measurement

[0131] The yield graph and XRD measurement results of the delta-phase perovskite crystals manufactured in Examples 1 to 20 are shown in FIGS. 5 and 6.

[0132] Through the XRD measurement results of FIGS. 5 and 6, it was confirmed that the same FAPBI3 crystals could be obtained even with different ratios and different concentrations of the precursor.

[0133]

[0134] Experimental Example 2: Solubility Evaluation and Purity Measurement of Synthesized Delta-Phase Perovskite Crystals

[0135] When producing crystals of Examples 1 to 30, the degree of solubility in gamma-butyrolactone (GBL), a reaction solvent, was measured according to the molar ratio and concentration of the precursor, and the results are shown in Table 2 below. The solubility evaluation was expressed as follows.

[0136] ◎: Recorded very well, ○: Recorded generally, △: Not well dissolved, ×: Not very dissolved

[0137] FAI: PbI2 molar ratio 1.6 M1.8 M2.0 M2.2 M2.4 M1:0.9◎◎○△△1:1◎◎○△△1.:1.1○○△△×1:1.25○△△××0.9: 1○○△△×1.1 : 1◎◎○△△1.25 : 1◎◎○○△

[0138] Additionally, the purity of the synthesized delta-phase perovskite crystals was measured, and the results are shown in Table 3 below.

[0139] FAI: PbI2 molar ratio 1.6 M1.8 M2.0 M2.2 M2.4 M1:0.9> 99.9%> 99.9%> 99.9%> 99.9%> 99.9%1:1> 99.9%> 99.9%> 99.9%> 99.9%> 99.9%1.:1.1> 99.9%> 99.9%> 99.9%> 99.9%> 99.9%1:1.25> 99.9%> 99.9%> 99.9%> 99.9%> 99.9%0.9 : 1> 99.9%> 99.9%> 99.9%> 99.9%> 99.9%1.1 : 1> 99.9%> 99.9%> 99.9%> 99.9%> 99.9%1.25 : 1> 99.9%> 99.9%> 99.9%> 99.9%> 99.9%

[0140] Looking at Tables 2 and 3 above, it was confirmed that even though the solubility differs depending on the molar ratio and concentration of the precursor to the solvent in the reaction solution, the purity of the crystals synthesized using these precursors was all 99.9% or higher, indicating that delta-phase perovskite crystals could be synthesized with a very high purity.

[0141]

[0142] Manufacturing Example 1: Manufacturing of a perovskite solar cell

[0143] As a source electrode, an organic substrate (thickness 1.1 mm, 15.0Ω / sq) coated with indium tin oxide (ITO) to a thickness of approximately 110 nm was sequentially cleaned with acetone and isopropyl alcohol (IPA) using an ultrasonic cleaner for 1 hour each.

[0144] Next, a 30 nm thick hole transport layer (NiO) is deposited on the ITO substrate by sputtering vacuum deposition. x ) was formed.

[0145] Next, the hole transport layer (NiO x) A solution was formed by dissolving 2PACz (2-(9H-carbazol- 9-yl) ethyl] phosphonic acid) in ethanol at a concentration of 2 mM, and spin-coating was performed, followed by heat treatment at 100°C for 10 minutes to form a 2PACz hole transport layer with a thickness of less than 2 nm.

[0146] Next, a yellow light-absorbing layer solution was prepared by dissolving the delta-phase perovskite crystals and CsPbBr3 perovskite crystals synthesized in Example 5 in a solvent mixed with DMF (dimethylformamide) and NMP (N-Methyl-2-pyrrolidone) in a volume ratio of 8:2.

[0147] And, after spin coating the yellow light-absorbing layer solution on top of the 2PACz hole transport layer, a perovskite light-absorbing layer ((FAPbI3)) having a perovskite crystal structure with a thickness of about 700 nm is formed by heat-treating at 150°C for 10 minutes and at 100°C for 20 minutes. 0.8 (CsPbBr3) 0.2 ) was formed.

[0148] Next, a 0.8 nm thick electron transport layer (LiF) was formed on top of the perovskite light-absorbing layer through thermal evaporation.

[0149] Next, a 13 nm thick electron transport layer (C) was deposited on top of the electron transport layer by thermal evaporation. 60 , fullerene) was formed.

[0150] Next, a solution formed by dissolving BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) in isopropyl alcohol was spin-coated on the electron transport layer to form a passivation layer with a thickness of less than 10 nm.

[0151] Next, silver (Ag) was deposited on the passivation layer to a thickness of 200 nm through thermal evaporation to form a source electrode, thereby forming a single element of a perovskite solar cell with an inverted structure (Active area: 0.096 cm 2 ) was manufactured.

[0152]

[0153] Manufacturing Examples 2 to 7

[0154] A single element of an inverse structure perovskite solar cell is manufactured using the same method as in Manufacturing Example 1 above, but (FAPbI3) 0.8 (CsPbBr3) 0.2 Perovskite of When forming a light-absorbing layer, instead of Example 5, a delta-phase perovskite crystal other than that shown in Table 4 was used to form a light-absorbing layer, and manufacturing examples 2 to 8 were performed, respectively.

[0155]

[0156] Comparative Manufacturing Example 1

[0157] A single element of an inverse structure perovskite solar cell is manufactured using the same method as in Manufacturing Example 1 above, but (FAPbI3) 0.8 (CsPbBr3) 0.2 Perovskite of When manufacturing a light-absorbing layer, precursors FAI, PbI2, and CsPbBr3, which are not delta-phase perovskite crystals, were dissolved in DMF and NMP to manufacture a light-absorbing layer solution, which was then used to form a light-absorbing layer.

[0158] Classification Delta-phase perovskite Classification Delta-phase perovskite Manufacturing example 1 Example 5 Manufacturing example 5 Example 25 Manufacturing example 2 Example 10 Manufacturing example 6 Example 30 Manufacturing example 3 Example 15 Manufacturing example 7 Example 35 Manufacturing example 4 Example 20 Comparative manufacturing example 1 FAI, PbI2

[0159]

[0160] Experimental Example 3

[0161] When manufacturing a single solar cell element manufactured in Manufacturing Examples 1 to 7 and Comparative Manufacturing Example 1 (Ref), UV-vis spectroscopy, X-ray diffraction, and steady state photoluminescence of the perovskite light-absorbing layer (thin film) before forming the electron transport layer (LiF) were measured, and the measurement results are shown in FIGS. 7 to 9, in that order.

[0162] Looking at the UV-vis spectroscopy measurement results of Fig. 7, it was confirmed that perovskite thin films made with crystals synthesized at different ratios were formed identically.

[0163] Looking at the X-ray diffraction measurement results of Fig. 8, it was confirmed that perovskite thin films made with crystals synthesized at different ratios were formed identically.

[0164] Looking at the photoluminescence measurement results of Fig. 9, it was confirmed that perovskite thin films made with crystals synthesized at different ratios were formed identically.

[0165]

[0166] Experimental Example 4: Performance Measurement of Solar Cell Devices

[0167] The current-voltage characteristics and efficiency of the solar cells manufactured in Manufacturing Examples 1 to 7 and Comparative Manufacturing Example 1 (Ref) were measured, and the results are shown in Table 5 and Figures 10 to 11 below.

[0168] When synthesizing FAPbI3 in delta phase, the molar ratio of FAI and PbI2 V oc (V)J sc (mA / cm 2)Fill Factor (%)PCE(%)Comparison Manufacturing Example 1 (Ref) 1.0720.6074.4816.53 Manufacturing Example 11:0.91.1220.5680.0418.54 Manufacturing Example 21:11.1220.5480.1718.57 Manufacturing Example 31:1.11.1020.7681.0118.62 Manufacturing Example 41:1.251.1120.6980.5118.56 Manufacturing Example 50.9:11.1220.6579.1518.33 Manufacturing Example 61.1:11.1220.5979.8818.46 Manufacturing Example 71.25:11.1020.9078.7518.22

[0169] Looking at Table 5 and Figures 10 to 11 above, it was confirmed that all of Manufacturing Examples 1 to 7 had relatively higher photoelectric conversion efficiencies than Comparative Manufacturing Example 1 (Ref).

[0170]

[0171] Manufacturing Example 8 and Comparative Manufacturing Example 2

[0172] (1) Manufacturing Example 8

[0173] Using the delta-phase perovskite crystals manufactured in Example 10 in the same manner as in Manufacturing Example 2, a light-absorbing layer solution and a single inverse-structured perovskite solar cell element using the same were manufactured. However, when synthesizing the delta-phase perovskite crystals of Example 10, as metal ion precursors, PbI2 having a purity of 95.0% (K Company, unit price 504 won / g), 99.0% (S Company, unit price 2533 won / g), and 99.9985% (T Company 4977 won / g) were used to manufacture delta-phase perovskite crystals, and three single inverse-structured perovskite solar cell elements were manufactured using the same.

[0174] At this time, the yield of delta-phase perovskite crystals according to the purity of PbI2 is shown in Table 6 below.

[0175] FAI: PbI2PbI2Purity95%PbI2Purity99%PbI2Purity99.9985%1:1(Solution concentration 2.4M)33%51%67%

[0176] (2) Comparative manufacturing example 2

[0177] A light-absorbing layer solution was prepared in the same manner as in Comparative Manufacturing Example 1, but PbI2 having purities of 95.0%, 99.0%, and 99.9985% was used to prepare each light-absorbing layer solution, and three single inverse-structure perovskite solar cell elements were manufactured using these.

[0178]

[0179] Experimental Example 5

[0180] The current-voltage characteristics and efficiency of the six types of solar cell single elements of Manufacturing Example 8 and Comparative Manufacturing Example 2 were measured, and the results are shown in Fig. 12.

[0181] Comparing the efficiency of the solar cell device of Manufacturing Example 8 in Table 5 and Fig. 12, it was confirmed that the purity of the metal ion precursor affects the yield of delta-phase perovskite crystals, but does not have a significant effect on the efficiency of the solar cell.

[0182] In addition, through comparison of Comparative Manufacturing Example 2 and Manufacturing Example 8 of Fig. 12, it was confirmed that there was only a difference in yield due to a difference in the purity of the PbI2 precursor used, and as a result, FAPbI3 crystals of the same quality could be obtained.

[0183]

[0184] Through the above examples and experimental examples, it was confirmed that delta-phase perovskite crystals can be manufactured with a high yield while using a smaller amount of chemicals than conventional synthesis methods, and that when applied as a light-absorbing layer material, a perovskite solar cell with excellent efficiency can be provided.

Claims

1. Step 1 of preparing a reaction solution by introducing a solvent into a reactor, and then 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; Step 2: heat-treating the above reaction solution at 150 to 170°C for 30 minutes to 3 hours to obtain a solution containing a precipitate; Step 3: Filtering the solution containing the precipitate from the second step to obtain the precipitate from the solution, and then washing the precipitate with a bad solvent; Step 4: Purifying the precipitate after performing the three-step washing process with an ether solvent and then filtering to obtain a filtrate; and A method for producing a delta-phase perovskite crystal, characterized in that it comprises performing a process including the step of drying the above filtrate to obtain a delta-phase perovskite crystal represented by the following chemical formula 3: [Chemical Formula 1] AX [Chemical Formula 2] BX2 [Chemical Formula 3] ABX3 In the above chemical formulas 1 and 3, A is formamidinium (FA), methylammonium (MA), FA x MA (1-x) (0 <X<1), 또는 N(R 1 )4 + and R 1 is a straight-chain 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 above chemical 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 - am.

2. A method for producing a delta-phase perovskite crystal, characterized in that in the first paragraph, the solvent of the first step comprises at least one selected from among γ-butyrolactone, γ-valerolactone, α-angelica lactone, α-methylene-γ-butyrolactone, α-hydroxy-γ-butyrolactone, and ε-caprolactone.

3. A method for producing a delta-phase perovskite crystal, characterized in that in the first paragraph, the reaction solution of step 1 contains a precursor including an organic anion precursor and a metal ion precursor at a concentration of 1.5 to 2.8 M.

4. A method for producing a delta-phase perovskite crystal, characterized in that in step 1, the reaction solution contains the organic anion precursor and the metal ion precursor in a molar ratio of 1:0.9 to 1.

25.

5. In the first paragraph, the solvent comprises a nitrile solvent including at least one selected from acetonitrile, propionitrile, and aminopropionitrile. The above ether solvent is an acyclic ether solvent, A method for producing a delta-phase perovskite crystal, characterized in that the ether solvent comprises at least one selected from diethyl ether, tert-butyl ethyl ether, diisopropyl ether, and dibutyl ether.

6. A method for producing a delta-phase perovskite crystal, characterized in that, in the first paragraph, the perovskite compound in the filtrate of the fourth step contains 99.0% or more of an alpha-phase perovskite compound.

7. A method for producing a delta-phase perovskite crystal, characterized in that the delta-phase perovskite crystal obtained in step 5 in paragraph 1 has a yield of 40.0% or more and a purity of 99.0% or more.

8. A delta-phase perovskite crystal manufactured by any one of the methods selected from among clauses 1 to 7, A delta-phase perovskite crystal characterized by being a perovskite crystal represented by the following chemical formula 3; [Chemical Formula 3] ABX3 In the above chemical formula 3, A is formamidinium (FA), methylammonium (MA. methylammonium), FA x MA (1-x) (0 <X<1), 또는 N(R 1 )4 + and R 1 is a straight-chain 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 L is R 2 C(=O)O - and R 2 is an alkyl group with 1 to 3 carbon atoms, 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 - am.

9. A light-absorbing layer of a perovskite solar cell characterized by being formed using the delta-phase perovskite crystal of Article 8.

10. A perovskite solar cell characterized by including the light-absorbing layer of claim 9.

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