Coating agent for forming large-area perovskite thin film and method for forming large-area perovskite thin film using same

Abstract

The present invention relates to: a method for forming a large-area perovskite thin film, enabling the manufacture of a high-quality large-area perovskite thin film; a coating agent used therefor; and a perovskite solar cell comprising same as a light-absorbing layer.

Description

Coating agent for forming large-area perovskite thin film and method for forming large-area perovskite thin film using the same

[0001] The present invention relates to a method for forming a large-area perovskite thin film capable of producing a high-quality large-area perovskite thin film, a coating agent used therein, and a perovskite solar cell including the same as a light-absorbing layer.

[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] 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 lowering the manufacturing cost of solar cells, and this has been an obstacle to large-scale utilization.

[0005] 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.

[0006] 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.

[0007] 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.

[0008] Among the solvents used to dissolve conventional perovskite precursors, a mixture of DMF (Dimethylformamide) and DMSO (Dimethyl Sulfoxide), which are polar aprotic solvents, was used. In particular, DMSO contains a (S=O) structure that can have a high dielectric constant value, and CH3NH3, which is a representative A-site material of perovskite. + Cations of the back (A +), the perovskite nucleation material of ABX3 was suppressed through the formation of a base adduct in the form of AX·PbX2·DMSO·Lewis (X=halogen ion) due to the low solubility of substances such as cesium chloride compounds, thereby forming high-quality perovskite. However, when substances such as cesium chloride compounds were used as solvents for wide-band gap perovskite precursors containing triple cation and triple halide substances, the binding force was weak, reducing the Lewis base characteristics, and the number of perovskite nucleation materials increased due to low Ea (activation energy), resulting in the formation of low-quality perovskite films with small grain sizes. As a result, existing perovskite films produced through large-area coating have low uniformity and thermal stability of the films, and because they require a non-solvent treatment process, waste is generated due to the use of non-solvents, which limits the mass production of perovskite.

[0009] The present invention has been made to overcome the above-described problems, and it has been found that when a Lewis salt adduct forming agent having a high dielectric constant value is introduced as a coating material for forming a perovskite thin film, the number of perovskite nucleation materials is suppressed, the intermediate phase is maintained for a long time, and a high-quality perovskite thin film having a large particle size can be formed, thereby completing the present invention. That is, the present invention provides a coating agent for forming a large-area perovskite thin film, a method for forming a large-area perovskite thin film using the same, and a solar cell including a perovskite thin film formed using the same as a light-absorbing layer.

[0010] In order to solve the above-described problem, the present invention relates to a coating agent for forming a large-area perovskite thin film, comprising: a compound represented by the following chemical formula 1; a Lewis salt adduct forming agent including at least one selected from diphenyl carbonate, dialkyl dicarbonate, and diaryl dicarbonate; and a perovskite precursor solution.

[0011] [Chemical Formula 1]

[0012]

[0013] In chemical formula 1, R1 and R2 are independently a hydrogen atom, a C1 to C5 straight-chain alkyl group, a C3 to C5 branched alkyl group, or a phenyl group.

[0014] As a preferred embodiment of the present invention, the coating agent for forming a large-area perovskite thin film of the present invention may include the Lewis salt adduct forming agent at a concentration of 5 mM to 100 mM.

[0015] As a preferred embodiment of the present invention, the perovskite precursor solution may include a perovskite precursor represented by the following chemical formula 2 and a solvent.

[0016] [Chemical Formula 2]

[0017] ABX3

[0018] In chemical formula 2, A includes two or more selected from monovalent organic ammonium ions and monovalent inorganic cations, M is a divalent metal ion, and X is F - , Cl - , Br - and I - Contains two or more halogen ions selected from among:

[0019] As a preferred embodiment of the present invention, the perovskite precursor may be a perovskite precursor represented by the following chemical formula 3.

[0020] [Chemical Formula 3]

[0021] A m A'1-m B(X n X' 1-n )3

[0022] In chemical formula 3, A is MA (methylammonium), FA (Formamidinium), EA (Ethylamine), GA (Guanidinium), or EDA (Ethylenediamine), and A' is Cs + , Na + , K + , NH4 + or Rb + and B is Pb 2+ , Sn 2+ , Pd 2+ , Cu 2+ , Ge 2+ , Sr 2+ , Cd 2+ , Ca 2+ , Ni 2+ , Mn 2+ , Fe 2+ , Co 2+ , Sn 2+ , Yb 2+ , or Eu 2+ , and X and X' are each independently Cl - , Br - or I - , and m and n are rational numbers satisfying 0.6≤m≤0.9 and 0.5≤n≤0.9.

[0023] As a preferred embodiment of the present invention, the perovskite precursor solution may contain the perovskite precursor at a concentration of 0.9 to 2.0 M.

[0024] As a preferred embodiment of the present invention, the solvent may include at least one selected from dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), thiourea, thioacetamide, pyridine, aniline, N,N'-Dimethylpropyleneurea (DMPU), 1-Cyclohexyl-2-pyrrolidone (CHP), acetonitrile (MeCN), and acetone.

[0025] Another object of the present invention is to provide a large-area (200 cm) coating using the coating agent described above. 2 (Above) A method for forming a perovskite thin film may be performed, comprising: a first step of preparing the coating agent for forming the thin film described above; a second step of performing a coating process and drying the coating agent on a substrate to form a wet-thin film including perovskite crystallized in an intermediate phase; and a third step of performing an annealing process on the wet-thin film to form a large-area perovskite thin film.

[0026] As a preferred embodiment of the present invention, the large-area perovskite thin film may have an average grain size of perovskite crystals present on the surface of 300 nm or more.

[0027] As a preferred embodiment of the present invention, the upper portion of the substrate coated with the coating solution may be a Si thin film layer, a hole transport layer, an electron transport layer, and / or a passivation layer.

[0028] As a preferred embodiment of the present invention, the coating process can be performed by blade coating, slot die coating, bar coating, inkjet coating, or spray coating.

[0029] As a preferred embodiment of the present invention, the drying may be performed together with the coating process or after the coating process is completed.

[0030] As a preferred embodiment of the present invention, the drying may be performed by a N2 or CDA (clean dry air) knife blowing process to evaporate the solvent of the coating agent.

[0031] As a preferred embodiment of the present invention, the sintering can be performed by heat treatment at 95 to 150°C for 5 to 30 minutes.

[0032] Another object of the present invention is to provide a perovskite solar cell comprising a large-area perovskite thin film formed by the above method using the above coating agent as a light-absorbing layer (or photoactive layer).

[0033] As a preferred embodiment of the present invention, the large-area perovskite thin film may have an average grain size of perovskite crystals present on the surface of 300 nm or more.

[0034] As a preferred embodiment of the present invention, the perovskite solar cell may be a tandem solar cell.

[0035] As a preferred embodiment of the present invention, there may be provided a tandem solar cell comprising an upper cell including a large-area perovskite thin film formed using the coating agent for forming a large-area perovskite thin film described above as a light-absorbing layer; and a lower cell including Si, Cu(In,Ga)Se3, CdTe or a perovskite compound as a light-absorbing layer.

[0036] The coating agent for forming a perovskite thin film of the present invention introduces a carbonate-based compound having a higher dielectric constant than a solvent such as DMSO (dimethyl sulfoxide) as a Lewis salt adduct forming agent, so that the Lewis salt (lewis base) characteristics of the adduct formed when forming a perovskite compound are not reduced due to the strong bonding force with the metal halide, and thus, due to the high Ea (activation energy), the number of nucleation materials of perovskite can be suppressed, and the intermediate phase can be maintained for a long time, and as a result, a high-quality perovskite thin film having a large grain size can be formed, and in addition, 200 cm 2 The above large-area perovskite thin film can be manufactured, which can maximize the efficiency of large-area solar cells.

[0037] Figure 1 is an SEM measurement image of the surface of the perovskite thin film manufactured in Example 1 and Comparative Example 1.

[0038] Figure 2 is an SEM measurement image of a cross-section of a perovskite thin film manufactured in Example 1 and Comparative Example 1.

[0039] Hereinafter, the present invention will be described in more detail through a method for forming a large-area perovskite thin film. Here, the large area is an area of ​​200 cm 2 Ideally 250 cm 2 It means the area above.

[0040] The present invention can form and obtain a large-area perovskite thin film by performing a process including: a first step of preparing a coating agent for forming a large-area perovskite thin film; a second step of performing a coating process and drying the coating agent on a substrate to form a wet-thin film including a perovskite crystallized in an intermediate phase; and a third step of performing an annealing process on the wet-thin film to form the large-area perovskite thin film.

[0041] The coating agent for forming the large-area perovskite thin film in the first step (hereinafter referred to as “coating agent”) includes a compound represented by the following chemical formula 1; a Lewis salt adduct forming agent including at least one selected from diphenyl carbonate, dialkyl dicarbonate, and diaryl dicarbonate; and a perovskite precursor solution.

[0042] [Chemical Formula 1]

[0043]

[0044] In chemical formula 1, R1 and R2 are independently a hydrogen atom, a C1 to C5 straight-chain alkyl group, a C3 to C5 branched alkyl group, or a phenyl group, preferably a hydrogen atom or a C1 to C5 straight-chain alkyl group, and more preferably a hydrogen atom or a C1 to C2 straight-chain alkyl group.

[0045] The above coating agent may contain a Lewis salt adduct forming agent at a concentration of 5 mM to 100 mM, preferably at a concentration of 5 mM to 50 mM, and more preferably at a concentration of 6 mM to 30 mM. At this time, if the concentration of the Lewis salt adduct forming agent in the coating agent is less than 5 mM, the amount used may be too small, which may cause a problem in that the particle size of the formed perovskite thin film may be too small, and if used in excess of 100 mM, it is considered excessive use, and rather, a problem in that the perovskite crystals may be suppressed or the perovskite grains may be separated at the grain boundaries due to the excessive grain size may occur, so it is recommended to use it within the above range.

[0046] Among the coating components of step 1, the perovskite precursor solution may include a perovskite precursor represented by the following chemical formula 2 and a solvent.

[0047] [Chemical Formula 2]

[0048] ABX3

[0049] A in chemical formula 2 includes two or more selected from monovalent organic ammonium ions and monovalent inorganic cations, M is a divalent metal ion, and X is F - , Cl - , Br - and I - Contains two or more halogen ions selected from among:

[0050] The above perovskite precursor may preferably be a compound represented by the following chemical formula 3.

[0051] [Chemical Formula 3]

[0052] A m A' 1-m B(X n X' 1-n )3

[0053] In chemical formula 3, A is MA (methylammonium), FA (Formamidinium), EA (Ethylamine), GA (Guanidinium) or EDA (Ethylenediamine), and preferably, A is MA or FA.

[0054] And, A' of chemical formula 3 is Cs + , Na + , K + , NH4 + or Rb + , and preferably Cs + or Rb + am.

[0055] Also, B in chemical formula 3 is Pb 2+ , Sn 2+ , Pd 2+ , Cu 2+ , Ge 2+ , Sr 2+ , Cd 2+ , Ca 2+ , Ni 2+ , Mn 2+ , Fe 2+ , Co 2+ , Yb 2+ , or Eu 2+ and preferably Pb 2+ , Sn 2+ , Pd 2+ or Cu 2+ and more preferably Pb 2+ or Sn 2+ am.

[0056] In addition, each of X and X' in chemical formula 3 is independently Cl - , Br - or I - am.

[0057] And, m and n in chemical formula 3 are rational numbers satisfying 0.6≤m≤0.9 and 0.5≤n≤0.9, preferably rational numbers satisfying 0.65≤m≤0.85 and 0.55≤n≤0.85, and more preferably rational numbers satisfying 0.70≤m≤0.85 and 0.60≤n≤0.85.

[0058] And, the perovskite precursor solution may contain the perovskite precursor at a concentration of 0.9 to 2.0 M, preferably at a concentration of 1.0 to 1.6 M, and more preferably at a concentration of 1.10 to 1.50. At this time, if the concentration of the perovskite precursor in the precursor solution is less than 0.9 M, there may be a problem that the thickness of the perovskite is not sufficiently formed, and the density is low, so that a decrease in the current converted by receiving light may occur, and if it exceeds 2.0 M, there may be a problem that a wet-thin film is formed, or a problem that the range of time until the post-treatment thermal process is insufficient due to a rapid shortage of solvent after formation.

[0059] And, among the perovskite precursor solution components, the solvent may include at least one selected from among dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), thiourea, thioacetamide, pyridine, aniline, N,N'-Dimethylpropyleneurea (DMPU), 1-Cyclohexyl-2-pyrrolidone (CHP), acetonitrile (MeCN), and acetone, and preferably may include at least one selected from among DMSO, DMF, NMP, DMPU, and CHP.

[0060] Next, the description of the second step of the method for forming a large-area perovskite thin film of the present invention refers to an object to be coated with the coating solution of the first step, and the coating solution can be coated on the upper part of a Si thin film, the upper part of a hole transport layer, the upper part of an electron transport layer, or the upper part of a passivation layer.

[0061] And, the coating process of the second step can be performed by blade coating, slot die coating, bar coating, inkjet coating or spray coating, and preferably can be performed by blade coating, slot die coating or bar coating.

[0062] In addition, the above-described drying in the second step may be performed together with the coating process, or may be performed as a separate process after the completion of the coating process. A preferred example of a drying method is N2 blowing using an air knife, and the solvent in the coating agent may be evaporated through drying, but the present invention is not limited thereto.

[0063] And, when the above drying is performed, a wet-thin film containing perovskite crystallized in an intermediate phase is formed.

[0064] Next, the third step of the annealing of the large-area perovskite thin film forming method of the present invention can be performed by heat treatment at 95 to 150°C for 5 to 30 minutes, and preferably, by heat treatment at 98 to 140°C for 5 to 30 minutes.

[0065] The large-area perovskite thin film formed by performing the processes 1 to 3 described above has an average grain size of the perovskite crystals present on the surface of 300 nm or more, preferably 350 nm to 800 nm, and more preferably 400 to 750 nm. Such a large-area perovskite thin film has excellent uniformity and thermal stability and can be formed and manufactured with high mass productivity.

[0066] The present invention can provide a perovskite solar cell having excellent photovoltaic conversion efficiency (PCE) by forming a light-absorbing layer of a solar cell using the coating agent and method for forming a perovskite thin film described above. The solar cell of the present invention can be a pin-structured perovskite solar cell, an inverse structured perovskite solar cell, a tandem perovskite solar cell, a tandem silicon / perovskite heterojunction solar cell, or a tandem perovskite / perovskite heterojunction solar cell.

[0067] For example, in a tandem solar cell composed of a silicon lower cell and a perovskite upper cell, a large-area perovskite light-absorbing layer can be formed on the light-absorbing layer of the upper cell using the coating agent and method of the present invention.

[0068] In addition, in a tandem solar cell composed of a lower cell including Cu(In,Ga)Se3, CdTe or a perovskite compound as a light-absorbing layer and a perovskite upper cell, a perovskite light-absorbing layer can be formed in the light-absorbing layer of the upper cell using the coating agent and method of the present invention.

[0069] In addition, a preferred embodiment of a perovskite solar cell is a solar cell including a laminated body having a 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.

[0070] Additionally, if the solar cell is an inverse structure perovskite solar cell, the laminate may be laminated on top of a drain electrode.

[0071] 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.

[0072] Hereinafter, a method for manufacturing the laminate constituting the perovskite solar cell will be described in detail. The laminate may 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.

[0073] 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.

[0074] 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′-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′-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)), PEDOT:PSS It may include poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate), PTAA (poly(triarylamine)), 2-PACz, and / or MeO-2PACz.

[0075] 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.

[0076] Next, the light absorption layer is a large-area thin film layer formed using the coating agent and method of the present invention described above.

[0077] 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.

[0078] 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.

[0079] Additionally, the solar cell may further include a passivation layer between the light absorption layer and the electron transport layer.

[0080] 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, and further, as a preferred embodiment, a tandem silicon / perovskite heterojunction solar cell may be sequentially laminated, in which a silicon solar cell substrate (first electrode) - an ITO conductive transparent thin film layer - a hole transport layer - an organic surface layer - a large-area perovskite thin film layer (a light absorbing layer) - an electron transport layer - a passivation layer (or a buffer layer) - a TCO layer - a source electrode (a second electrode) are sequentially laminated. At this time, the hole transport layer, the electron transport layer, and the source electrode are the same as described above.

[0081] 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.

[0082] [Example]

[0083] Example 1: Preparation of perovskite coating and perovskite thin film

[0084] (1) Preparation of perovskite precursor solution

[0085] A perovskite precursor solution containing 1.3 M of a perovskite compound represented by the following chemical formula 3-1 was prepared by mixing CsBr, FAI, and PbI2 precursors.

[0086] [Chemical Formula 3-1]

[0087] A m A' 1-m B(X n X' 1-n )3

[0088] In chemical formula 3-1, A is FA (Formamidinium) and A' is Cs + and B is Pb 2+ , X is I - , X' is Br - , m is 0.8, and n is 0.8.

[0089] (2) Preparation of coating agent for forming large-area perovskite thin films

[0090] After adding a Lewis salt adduct forming agent represented by the following chemical formula 1-1 to the perovskite precursor solution, the solution was stirred at approximately 25°C for 1 hour to prepare a coating agent for forming a large-area perovskite thin film. At this time, the concentration of the Lewis salt adduct forming agent in the coating agent was 10 mM.

[0091] [Chemical Formula 1-1]

[0092]

[0093] In chemical formula 1-1, R1 and R2 are hydrogen atoms.

[0094]

[0095] Comparative Example 1

[0096] The perovskite precursor solution manufactured in Example 1 above was prepared as a coating agent for forming a large-area perovskite thin film.

[0097] Examples 2 to 4 and Comparative Example 2

[0098] A coating agent for forming a large-area perovskite thin film was prepared in the same manner as in Example 1, but the concentration and type of the Lewis salt adduct forming agent were changed as shown in Table 1 below, and Examples 2 to 4 and Comparative Example 2 were each prepared.

[0099]

[0100] Examples 5 to 6 and Comparative Examples 3 to 4

[0101] A coating agent for forming a large-area perovskite thin film was prepared in the same manner as in Example 1, but each coating agent was prepared using a perovskite precursor solution having a different concentration as shown in Table 1 below, and Examples 5 to 6 and Comparative Examples 3 to 4 were performed, respectively.

[0102]

[0103] Example 7

[0104] A coating agent for forming a large-area perovskite thin film was prepared in the same manner as in Example 1, but instead of using Chemical Formula 1-1 as the Lewis salt adduct forming agent, a Lewis salt adduct forming agent represented by Chemical Formula 1-2 was used.

[0105] [Chemical Formula 1-2]

[0106]

[0107] In chemical formula 1-1, R1 and R2 are methyl groups.

[0108]

[0109] Example 8

[0110] A coating agent for forming a large-area perovskite thin film was prepared in the same manner as in Example 1, but as a Lewis salt adduct forming agent, a Lewis salt adduct forming agent represented by Chemical Formula 1-1 and diethyl carbonate were mixed and used in a weight ratio of 1:0.23.

[0111]

[0112] Example 9

[0113] A coating agent for forming a large-area perovskite thin film was prepared in the same manner as in Example 1, but when preparing the perovskite precursor, a perovskite compound represented by the following chemical formula 3-2 was used instead of the perovskite compound represented by the above chemical formula 3-1.

[0114] [Chemical Formula 3-2]

[0115] A m A' 1-m B(X n X' 1-n )3

[0116] In chemical formula 3-2, A is MA (methylammonium) and A' is Cs + and B is Pb 2+ , X is I - , X' is Br - , m is 0.72, and n is 0.64.

[0117]

[0118] Comparative Example 5

[0119] A coating agent for forming a large-area perovskite thin film was prepared in the same manner as in Example 1, but when preparing the perovskite precursor, a perovskite compound represented by the following chemical formula 3-3 was used instead of the perovskite compound represented by the above chemical formula 3-1.

[0120] [Chemical Formula 3-3]

[0121] A m A' 1-m B(X n X' 1-n )3

[0122] In chemical formula 3-3, A is FA (Formamidinium), A' is MA (methylammonium), and B is Pb. 2+ , X is I - , X' is Br - , m is 0.78, and n is 0.67.

[0123] ClassificationPerovskite precursor solutionPerovskite precursor concentrationCoating agentLewis salt adduct forming agent concentrationLewis salt adduct typePerovskite compoundExample 11.30 M10 mMChemical formula 1-1Chemical formula 3-1Example 21.30 M30 mMChemical formula 1-1Chemical formula 3-1Example 31.30 M50 mMChemical formula 1-1Chemical formula 3-1Example 41.30 M100 mMChemical formula 1-1Chemical formula 3-1Example 51.00 M30 mMChemical formula 1-1Chemical formula 3-1Example 61.80 M30 mMChemical formula 1-1Chemical formula 3-1Example 71.30 M30 mMChemical formula 1-2Chemical formula 3-1Example 81.30 M30 mMChemical formula 1-1 and diethyl carbonate Chemical formula 3-1 Example 91.30 M30 mM Chemical formula 1-1 Chemical formula 3-2 Comparative example 11.30 M×× Chemical formula 3-1 Comparative example 21.30 M115 mM Chemical formula 1-1 Chemical formula 3-1 Comparative example 30.80 M30 mM Chemical formula 1-1 Chemical formula 3-1 Comparative example 42.10 M30 mM Chemical formula 1-1 Chemical formula 3-1 Comparative example 51.50 M40 mM Chemical formula 1-1 Chemical formula 3-3

[0124]

[0125] Manufacturing Example 1: Manufacturing of a tandem silicon / perovskite heterojunction solar cell

[0126] As the first electrode, a 20 nm layer of ITO conductive thin film was formed on a silicon solar cell substrate measuring 6 inches in width and height by physical deposition, and then NiO was formed as a hole transport layer on an ITO conductive transparent substrate by physical deposition process. x 20nm was formed.

[0127] Next, 200 μl of the organic interface layer solution was dropped onto the hole transport layer (NiOx) and spin-coated at 3000 rpm for 30 seconds, followed by heat treatment at 100°C.

[0128] At this time, the organic interface layer solution was prepared with 2PACz ([2-(9H-Carbazol-9-yl)ethyl]phosphonic Acid) in ethanol solvent at a concentration of 2 mM.

[0129] Next, the coating agent for forming a large-area perovskite thin film manufactured in Example 1 was coated using a blade device, and then the coating surface was blown with 99% nitrogen and heat-treated at 100°C for 20 minutes to form a film with a thickness of about 550 to 560 nm and an area of ​​about 233 cm. 2 A light-absorbing layer was formed.

[0130] Next, a 13 nm thick fullerene (C) is placed on top of the light absorbing layer as an electron transport layer. 60 ) layer was formed. 10 nm of SnO2 was deposited on the electron transport layer using an ALD process. The SnO2 plays two roles: an electron transport layer and a buffer layer.

[0131] Afterwards, a top TCO layer was formed with a thickness of 70 nm by physical vapor deposition, and finally, a second electrode of Ag was formed using thermal vapor deposition equipment to fabricate a large-area perovskite / silicon tandem photoelectric conversion device.

[0132]

[0133] Manufacturing Examples 2 to 9 and Comparative Manufacturing Examples 1 to 5

[0134] A large-area perovskite / silicon tandem photoelectric conversion device was manufactured using the same method as Manufacturing Example 1, but when manufacturing the light absorption layer, a coating agent for forming a large-area perovskite thin film was used differently as shown in Table 2 below, and a large-area perovskite / silicon tandem photoelectric conversion device was manufactured, and Manufacturing Examples 2 to 9 and Comparative Manufacturing Examples 1 to 5 were performed, respectively.

[0135]

[0136] Experimental Example 1: SEM (scanning electron microscope) and measurement of average particle size of light-absorbing layer

[0137] The SEM images of the surface of the light-absorbing layer of the tandem photoelectric conversion element of Manufacturing Example 1 (Example 1) and Comparative Manufacturing Example 1 (Comparative Example 1) are shown in Fig. 1, and the SEM measurement images of the cross-section are shown in Fig. 2. The perovskite crystal form constituting the light-absorbing layer is plate-shaped.

[0138] In addition, the average grain size of the perovskite crystals present on the surface of the perovskite thin film constituting the light-absorbing layer of the manufacturing example and comparative manufacturing example was measured, and the results are shown in Table 2 below.

[0139] Type of coating agent for forming perovskite thin film with a large area Light absorbing layer Thickness (nm) Average crystal size of surface (nm) PbI2 Detection (unreacted) Manufacturing example 1 Example 1 550 ~ 560 500 ~ 550 Detection × Manufacturing example 2 Example 2 570 ~ 620 550 ~ 600 Detection × Manufacturing example 3 Example 3 600 ~ 700 700 ~ 710 Detection × Manufacturing example 4 Example 4 700 ~ 800 740 ~ 750 Detection × Manufacturing example 5 Example 5 400 ~ 450 380 ~ 440 Detection × Manufacturing example 6 Example 6 760 ~ 800 750 ~ 790 Detection × Manufacturing example 7 Example 7 60 ~ 610 540 ~ 590 Detection × Manufacturing Example 8 Example 8 570 ~ 625 560 ~ 610 Detection × Manufacturing Example 9 Example 9 565 ~ 615 550 ~ 600 Detection × Comparative Manufacturing Example 1 Comparative Example 1 440 ~ 450 74 ~ 150 Detection × Comparative Manufacturing Example 2 Comparative Example 2 600 ~ 700 800 ~ 900 Detection ○ Comparative Manufacturing Example 3 Comparative Example 3 350 ~ 400 300 ~ 450 Detection × Comparative Manufacturing Example 4 Comparative Example 4 900 ~ 1100 850 ~ 1100 Detection ○ Comparative Manufacturing Example 5 Comparative Example 5 750 ~ 800 800 ~ 900 Detection ○

[0140]

[0141] Experimental Example 2: Performance Measurement of Solar Cell Devices

[0142] The current-voltage characteristics and efficiency of the solar cells manufactured in Manufacturing Examples 1 to 9 and Comparative Manufacturing Examples 1 to 5 were measured, and the results are shown in Table 3 below.

[0143] Classification coating liquid type Open circuit voltage (V) oc , V) short-circuit current density (J) sc , mA / cm 2 )Fill factor (FF, %)Photoelectric conversion efficiency (%)Manufacturing example 1 Example 11.839118.18472.27124.169Manufacturing example 2 Example 21.832218.20172.07224.034Manufacturing example 3 Example 31.829118.50171.01224.030Manufacturing example 4 Example 41.780218.80270.05423.448Manufacturing example 5 Example 51.801017.80170.01222.445Manufacturing example 6 Example 61.770218.80167.01222.302Manufacturing example 7 Example 71.831218.19972.10124.029 Manufacturing Example 8 Example 81.829918.28572.00524.092 Manufacturing Example 9 Example 91.830118.21172.09524.027 Comparative Manufacturing Example 1 Comparative Example 11.828817.97570.74923.258 Comparative Manufacturing Example 2 Comparative Example 21.770218.82068.01222.658 Comparative Manufacturing Example 3 Comparative Example 31.775117.70269.80121.933 Comparative Manufacturing Example 4 Comparative Example 41.760218.81066.11221.889 Comparative Manufacturing Example 5 Comparative Example 51.771018.76066.01221.919

[0144] As can be confirmed through Table 3 above, in the case of tandem devices of manufacturing examples 1 to 9, the short-circuit current density (J) is high due to the large crystal size of the light absorption layer. SC ) increases, and even though the perovskite thickness increases, the open circuit voltage (V) is affected by the relatively reduced grain boundary. OC) increases, and it can be confirmed that the efficiency is improved in all efficiency parameters, such as the fill factor (FF) is improved due to the improved perovskite thin film quality, compared to the photoelectric conversion device of Comparative Manufacturing Example 1. In addition, in the case of Comparative Manufacturing Example 2, in which the coating agent of Comparative Example 2 was applied, which was manufactured using 115 mM, which is more than 100 mM in the concentration of the Lewis salt adduct forming agent in the coating agent, the thickness of the light absorbing layer and the size of the crystals were not a major problem, but there was a problem in that the FF and voltage (VOC) were greatly reduced due to the generation of PbI2 crystals that could not be perovskite crystallized due to the increase in intermediates combined with the perovskite precursor and the Lewis salt.

[0145] In addition, in the case of Comparative Manufacturing Example 3, in which the coating agent of Comparative Example 3 was applied, in which the perovskite precursor concentration was 0.80 M, which is less than 0.90 M, when manufacturing the coating agent, there was a problem of current reduction, voltage, and FF reduction due to insufficient crystal size and thickness, compared to Manufacturing Example 5 (Example 5). In addition, in the case of Comparative Manufacturing Example 3, in which the coating agent of Comparative Example 3 was applied, in which the perovskite precursor concentration was 0.80 M, which is less than 0.90 M, when manufacturing the coating agent, there was a problem of significant current reduction, compared to Manufacturing Example 6 (Example 6).

[0146] In addition, in the case of Comparative Manufacturing Example 5, in which a coating agent using a perovskite compound of Chemical Formula 3-3 was applied, the photoelectric conversion efficiency was relatively low compared to Manufacturing Examples 1 to 9, and through this, it was confirmed that the use of a Lewis salt adduct forming agent for a perovskite compound other than a Cs-based perovskite compound is inappropriate.

[0147]

[0148] Through the above examples and experimental examples, it was confirmed that a high-quality, large-area perovskite thin film with a large average particle size and uniformity can be commercially manufactured, and it was confirmed that a perovskite solar cell manufactured using the same has a high photoelectric conversion efficiency.

Claims

1. A Lewis salt adduct forming agent comprising at least one selected from the group consisting of a compound represented by the following chemical formula 1, diphenyl carbonate, dialkyl dicarbonate, and diaryl dicarbonate; and Perovskite precursor solution; A coating agent for forming a large-area perovskite thin film, characterized by including: [Chemical Formula 1] In chemical formula 1, R1 and R2 are independently a hydrogen atom, a C1 to C5 straight-chain alkyl group, a C3 to C5 branched alkyl group, or a phenyl group.

2. A coating agent for forming a large-area perovskite thin film, characterized in that it comprises the Lewis salt adduct forming agent in a concentration of 5 mM to 100 mM in the first paragraph.

3. A coating agent for forming a large-area perovskite thin film, characterized in that the perovskite precursor solution in the first paragraph includes a perovskite precursor represented by the following chemical formula 2 and a solvent; [Chemical Formula 2] ABX3 In chemical formula 2, A includes two or more selected from monovalent organic ammonium ions and monovalent inorganic cations, M is a divalent metal ion, and X is F - , Cl - , Br - and I - Contains two or more halogen ions selected from among:

4. A coating agent for forming a large-area perovskite thin film, characterized in that in the third paragraph, the perovskite precursor solution contains the perovskite precursor at a concentration of 0.9 to 2.0 M.

5. A coating agent for forming a large-area perovskite thin film, characterized in that in the third paragraph, the solvent comprises at least one selected from among dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), thiourea, thioacetamide, pyridine, aniline, N,N'-Dimethylpropyleneurea (DMPU), 1-Cyclohexyl-2-pyrrolidone (CHP), acetonitrile (MeCN), and acetone.

6. A coating agent for forming a large-area perovskite thin film, characterized in that the perovskite precursor in the third paragraph is a perovskite precursor represented by the following chemical formula 3; [Chemical Formula 3] A m A' 1-m B(X n X' 1-n )3 In chemical formula 3, A is MA (methylammonium), FA (Formamidinium), EA (Ethylamine), GA (Guanidinium), or EDA (Ethylenediamine), and A' is Cs + , Na + , K + , NH4 + or Rb + and B is Pb 2+ , Sn 2+ , Pd 2+ , Cu 2+ , Ge 2+ , Sr 2+ , Cd 2+ , Ca 2+ , Ni 2+ , Mn 2+ , Fe 2+ , Co 2+ , Sn 2+ , Yb 2+ , or Eu 2+ , and X and X' are each independently Cl - , Br - or I - , and m and n are rational numbers satisfying 0.6≤m≤0.9 and 0.5≤n≤0.

9.

7. Area 200 cm 2 As a method for forming a large-area perovskite thin film, Step 1: preparing a coating agent selected from any one of claims 1 to 6; Step 2: forming a wet-thin film containing perovskite crystallized in an intermediate phase by performing a coating process and drying on the upper part of the substrate with the above coating agent; and Step 3: Forming a large-area perovskite thin film by performing an annealing process on the above wet film; A method for forming a large-area perovskite thin film, characterized by performing a process including:

8. A method for forming a large-area perovskite thin film, characterized in that in the 7th paragraph, the large-area perovskite thin film has an average grain size of perovskite crystals on the surface of the large-area perovskite thin film of 300 nm or more.

9. A method for forming a large-area perovskite thin film, characterized in that in paragraph 7, the substrate on which the coating agent is coated is a Si thin film layer, a hole transport layer, an electron transport layer, or a passivation layer.

10. A method for forming a large-area perovskite thin film, characterized in that in the 7th paragraph, the coating process is performed by blade coating, slot die coating, bar coating, inkjet coating, or spray coating.

11. A method for forming a large-area perovskite thin film, characterized in that in paragraph 7, the drying is performed together with the coating process or after the coating process is completed.

12. A method for forming a large-area perovskite thin film, characterized in that in the 11th paragraph, the drying is performed by a N2 or CDA (clean dry air) knife blowing process to evaporate the solvent.

13. A method for forming a large-area perovskite thin film, characterized in that in the 7th paragraph, the calcination is performed by heat treatment at 95 to 150°C for 5 to 30 minutes.

14. A large-area perovskite thin film formed with a coating agent selected from any one of claims 1 to 6 is included as a light-absorbing layer. A large-area perovskite solar cell, characterized in that the above large-area perovskite thin film has an average grain size of perovskite crystals on the surface of 300 nm or more.

15. An upper cell including a large-area perovskite thin film formed with a coating agent selected from any one of claims 1 to 6 as a light-absorbing layer; and A lower cell comprising Si, Cu(In,Ga)Se3, CdTe or a perovskite compound as a light absorbing layer; A perovskite tandem solar cell, wherein the large-area perovskite thin film of the upper cell has an average grain size of perovskite crystals on the surface of 300 nm or more.

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