KR102173288B1 - Perovskite solar cells with hole transporting layers of high water resistance, and fabricating method therof - Google Patents

Abstract

The present invention relates to a perovskite solar cell having water resistance, and more particularly, in a solar cell comprising a substrate, a first electrode, a photoactive layer made of N-type and P-type semiconductors, a hole transport layer, and a second electrode. , By including a hole transport agent and an aromatic compound having at least 6 or more fluorine atoms (water resistance improving agent) in the hole transport layer, there is an advantage of providing a solar cell having excellent water resistance and excellent hole transport characteristics.

Description

Perovskite solar cells with hole transporting layers of high water resistance, and fabricating method therof}

The present invention relates to a perovskite solar cell having water resistance, and more particularly, by including a hole transport agent and an aromatic compound having 6 or more fluorine atoms in a molecule in the hole transport layer, excellent water resistance and excellent hole transport characteristics. It relates to a solar cell and its manufacturing method.

A solar cell (Solar Cell or Photovoltaic Cell) is a key element of photovoltaic power generation that directly converts sunlight into electricity, and is currently widely used for power supply from space to home. In the early days when solar cells were first made, they were mainly used for space, but as they experienced two oil shocks in the 1970s, attention was paid to the possibility of using them as ground power sources, and due to active research and development, there was limited ground power generation from the 1980s. Started to be used as a dragon. Recently, it has been used in aviation, weather, and communication fields, and solar vehicles and solar air conditioners are also attracting attention.

These solar cells mainly use silicon semiconductors, but there is a problem that the power generation cost is high due to the raw material price of high purity (6N~9N) silicon semiconductors and the complexity of the solar cell manufacturing process using the same. In other words, since it is 3 to 10 times higher than the conventional fossil fuel power generation unit, the market is growing by the subsidy policy of each country. For this reason, research and development of solar cells that do not use silicon have been activated, and from the 1990s, dye-sensitized solar cells (DSSC) using dyes, which are organic semiconductor materials, and polymer solar cells (Polymers) using conductive polymers. Solar Cell: PSC) has begun to be studied in earnest. Although organic semiconductor-based solar cells such as DSSC and PSC have not reached the commercialization stage despite many efforts from academia and industry, the emergence of perovskite solar cells that combine the advantages of DSSC and PSC. As a result, expectations for next-generation solar cells are rising.

Perovskite solar cell is a fusion type solar cell of conventional DSSC and PSC. It has excellent reliability because it does not use liquid electrolyte like DSSC, and it is a solar cell that can be highly efficient due to the optical excellence of perovskite, and is a recent process improvement. In addition, efficiency is continuously improving through material improvement and structural improvement. The structure of such a perovskite solar cell is shown in FIG. 1. 1, a perovskite solar cell includes a substrate, a first electrode, a blocking layer, a photoactive layer composed of an N-type semiconductor (metal oxide) and a P-type semiconductor (perovskite compound), and holes. It consists of a transport layer and a second electrode. The principle of operation of this perovskite solar cell is as follows. The perovskite compound absorbs sunlight to excite electrons, injects the excited electrons into the conduction band of the N-type semiconductor (mainly metal oxide), and the injected electrons pass through the N-type semiconductor and the blocking layer to form the first It is collected on the electrode and transferred to an external circuit. The operation of the solar cell is completed by transferring the electrons to the P-type semiconductor through the hole transport layer after the electrons reach the second electrode through an external circuit.

Meanwhile, since perovskite solar cells may be deteriorated by moisture and oxygen during operation, each layer formed from the atmosphere must be blocked. In general, there is a method of attaching a glass or a protective cap with an adhesive or a method of blocking moisture and oxygen from the atmosphere by forming a thin passivation layer on the second electrode.

In order to accelerate the commercialization of the current perovskite solar cell and replace the conventional expensive silicon solar cell, securing long-term reliability is the most important item. As described above, when the perovskite solar cell device as shown in FIG. 1 is completed, a protective cap or passivation layer must be formed on the top of the perovskite solar cell device to prevent the inflow of moisture and oxygen in the atmosphere. However, there is a problem that the protective cap or passivation layer does not completely block moisture and oxygen in the atmosphere. In this way, the moisture introduced from the atmosphere reaches the ionic perovskite compound (P-type semiconductor) through the hole transport layer, and the perovskite compound exposed to the moisture functions as a P-type semiconductor by destruction of the crystal lattice. There is a problem to be lost.

Korean Patent Registration No. 10-169285 "Inorganic nanomaterial-based hydrophobic charge transporter, method for manufacturing the same, and organic-inorganic complex perovskite solar cell including the same" Republic of Korea Patent Publication No. 10-2019-0007812 "Perovskite solar cell including hybrid hole transport layer and its manufacturing method" Korean Patent Registration No. 10-1619780 “Hole transport compound for non-organic hybrid perovskite solar cells”

Y. Zhang et al., RSC Adv., 6, 108888-108895 (2016) J. Ye et al., RSC Adv., 5, 36356-36361

The present invention was devised to solve the above problems, and the hole transport layer of a perovskite solar cell contains a hole transport agent and an aromatic compound having 6 or more fluorine atoms, so that the perovskite compound flows from the atmosphere. It is to provide a solar cell that can prevent contact with the generated moisture and improve hole transport characteristics.

An object of the present invention is a substrate; A first electrode formed on the substrate; A photoactive layer formed on the first electrode and made of an N-type semiconductor and a P-type semiconductor; A hole transport layer formed on the photoactive layer; In a solar cell comprising a second electrode formed on the hole transport layer, the hole transport layer comprises a hole transport agent and a fluorine-containing aromatic compound containing 6 or more fluorine atoms in a molecule as shown in the following general formula 1 or 2 ( Hereinafter, it is an object of the present invention to provide a perovskite solar cell having a high water resistance hole transport layer, characterized in that it is composed of a single or a plurality of).

[General Formula 1]

[General Formula 2]

In the general formula 1, X is selected from carbon (C), silicon (Si), germanium (Ge), and tin (Sn).

Y is hydrogen; Halogen atom; Hydroxy group; Cyano group; A substituted or unsubstituted C1-C30 acetate group; A ketone group of substituted or unsubstituted C1-C30 (C1 means 1 carbon atom and C30 means 30 carbon atoms); A substituted or unsubstituted C1-C30 vinyl group; A substituted or unsubstituted C1-C30 alkoxy group; A substituted or unsubstituted C1-C30 alkyl group; A substituted or unsubstituted C1-C30 heteroalkyl group; A substituted or unsubstituted C1-C30 heteroalkoxy group; A substituted or unsubstituted C6-C30 aryl group; A substituted or unsubstituted C6-C30 arylalkyl group; A substituted or unsubstituted C6-C30 aryloxy group; A substituted or unsubstituted C2-C30 heteroaryl group; A substituted or unsubstituted C2-C30 heteroarylalkyl group; A substituted or unsubstituted C2-C30 heteroaryloxy group; A substituted or unsubstituted C5-C20 cycloalkyl group; A substituted or unsubstituted C2-C30 heterocycloalkyl group; A substituted or unsubstituted C1-C30 alkyl ester group; A substituted or unsubstituted C1-C30 heteroalkyl ester group; A substituted or unsubstituted C2-C30 aryl ester group; And a substituted or unsubstituted C2-C30 heteroaryl ester group.

In the general formulas 1 and 2, Z ₁ and Z ₂ may be the same or different as a fluorine-substituted aromatic functional group, and bis (pentafluorophenyl) phosphinyl group, trifluoro thienyl group, trifluoro pyrrolyl group, tetrafluoro pyrrolyl group, tetrafluoro pridinyl group, At least one is selected from pentafluoro phenyl group, heptafluoro naphthyl group, nonafluoro anthracenyl group, nonafluoro biphenyl group, octafluoro carbazoyl group, octafluoro phenothiazinyl group, and octafluoro phenoxazinyl group.

In General Formula 1, n is selected from 1 to 10 as the number of XY ₂ groups connected.

In the general formula 2, Me is selected from Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, Pd.

Another object of the present invention is to provide a method of manufacturing a highly water-resistant perovskite solar cell comprising a hole transporting agent and an aromatic compound having 6 or more fluorine atoms (water-resistant flavoring agent) in a hole transport layer.

Detailed description of the components and manufacturing steps of the present invention are as follows.

<Substrate/First Electrode Preparation and Cleaning>

The first electrode formed on the substrate is immersed in acetone, ethanol, distilled water, or a mixed solution thereof, followed by ultrasonic cleaning. As the substrate, any optically transparent material such as glass or plastic can be used. The first electrode is FTO (F-doped tin oxide), ITO (In ₂ O ₃ ~90% + SnO ₂ ~10%), IZO (In-doped zinc oxide), ZnO-Ga ₂ O ₃ , ZnO- A transparent and conductive transparent electrode such as Al ₂ O ₃ and SnO ₂ -Sb ₂ O ₃ may be used.

<Formation of blocking layer on top of the first electrode>

As mentioned above, the blocking layer is formed to improve efficiency by preventing the interfacial recombination of the first electrode and the hole transport agent, and materials such as TiO ₂ and ZnO may be exemplified as a material of the blocking layer. One method of forming the blocking layer is, for example, a method by chemical bath deposition. When the cleaned substrate/first electrode is immersed in a precursor solution (TiCl ₄ ) having a concentration of 40 mM and left at 70° C. for 30 minutes, titanium oxychloride Is coated on the surface of the first electrode, washed with distilled water and ethanol, and fired at high temperature (450-500°C) to form a TiO ₂ blocking layer. Another method is to dissolve Ti precursors such as Ti(IV) bis(ethylacetoacetato)-diisopropoxide, titanium(IV) isopropoxide, etc. in a solvent and then spin coating or spray coating and then calcination at high temperature to form a TiO ₂ blocking layer on the top of the first electrode. Can be formed. Meanwhile, in the case of ZnO, zinc acetate dihydrate and ethanolamine are dissolved in a solvent (2-methoxy ethanol), and then coated on the first electrode by a method such as spin coating and dried to form a ZnO blocking layer.

If there is no blocking layer, all electrons reaching the first electrode cannot be transferred to the external circuit. In other words, if there is no blocking layer, the upper surface of the first electrode is mostly in contact with the N-type semiconductor, but some of the electrons that have reached the first electrode are also in contact with the hole transport layer, so some of the electrons reaching the first electrode cannot be transferred to the external circuit. It reacts with (hole transporting material; HTM) and disappears. In this way, the photoelectric conversion efficiency is reduced by recombination, and in order to minimize the recombination phenomenon, a blocking layer is formed as shown in FIG. 1 to prevent direct contact between the first electrode and the hole transport agent. The blocking layer is formed for the purpose of improving the solar cell efficiency by preventing recombination, but there is no problem in the operation of the solar cell even without the blocking layer.

.

<Formation of an N-type semiconductor layer on top of the blocking layer>

After forming a thin film by coating a paste containing N-type semiconductor nanoparticles on the blocking layer, heat treatment (450-550°C) in air or in an oxygen atmosphere for about 30 to 60 minutes is performed on the top of the blocking layer. Layers can be formed. In some cases, the N-type semiconductor layer is immersed in and left to stand in a TiCl ₄ solution, and then additional heat treatment (450 ~ 550°C) is performed. The material for the N-type semiconductor layer includes a metal oxide selected from the group consisting of TiO ₂ , Al ₂ O ₃ , SnO ₂ , ZnO, WO ₃ , Nb ₂ O ₅ , TiSrO ₃ , ZrO ₂ and combinations thereof It may be, but may not be limited thereto. In addition, as a method of coating the N-type semiconductor on the blocking layer, doctor blade coating, screen printing, flexography method, gravure printing method, or the like may be used.

<Joining P-type semiconductor to the surface of N-type semiconductor>

In order to operate as a solar cell, a P-type semiconductor must be bonded to the surface of the N-type semiconductor as shown in FIG. 1. By absorbing light, the P-type semiconductor transfers electrons from the ground state to the excited state to form an electron-hole pair, and the excited electrons are injected into the conduction band of the N-type semiconductor and pass through the blocking layer to the first electrode. It moves and generates electromotive force.

As the P-type semiconductor material, a compound represented by RMX ₃ having a well-known perovskite crystal structure may be used. Where R is C _n H _{2n + 1} NH ₃ ⁺ (n is an integer from 1 to 9), NH ₄ ⁺ , HC(NH ₂ ) ₂ ⁺ , CS ⁺ , NF ₄ ⁺ , NCl ₄ ⁺ , PF ₄ ⁺ , PCl ₄ ⁺ , CH ₃ PH ₃ ⁺ , CH ₃ AsH ₃ ⁺ , CH ₃ SbH ₃ ⁺ , PH ₄ ⁺ , AsH ₄ ⁺ , SbH ₄ ^{+ It} means a monovalent cation selected from the group consisting of, and combinations thereof, M is Pb ^{2 +,} Sn ^{2 +,} Ge ^{2 +,} and a two-valent metal cation, including those selected from the group consisting of the combinations thereof, and, X is ^{F -, Cl -, Br -} , I - , such as It means a halogen anion.

There are several known methods for bonding the P-type semiconductor to the surface of the N-type semiconductor. Here, a brief description of the case where R is an alkylammonium ion is as follows.

After preparing a solution by mixing alkylammonium halide, a precursor material of perovskite, and metal halide, coating (spin coating, dip coating, etc.) on the top of the N-type semiconductor and heat treatment (40~300℃) to form a PN junction It is possible to do it. In addition, after separately preparing an alkylammonium halide solution and a metal halide solution, a substrate including the N-type semiconductor is sequentially deposited or spin-coated, and then heat treated to form a P-N junction. In addition to the above methods, a method of vacuum-depositing an alkylammonium halide precursor and a metal halide precursor, a method of vacuum-depositing the finally synthesized perovskite material, etc. are possible, but are not limited thereto. When the PN conjugation process is performed by preparing a solution of the precursor or perovskite material, γ-butyrolactone, dimethylsulfoxide, dimethylformamide, N-methyl-2-pyrrolidone, dimethylacetamide, etc. may be used, but is not limited thereto. Does not.

<Formation of high water resistance hole transport layer>

Perovskite, a P-type semiconductor, absorbs light to form an electron-hole pair, and the hole transport layer serves to transfer the generated holes to the second electrode. The hole transport agent constituting the hole transport layer is preferably a compound that has an ability to transport holes and has an excellent ability to form a thin film as well as to block electrons. Specifically, low molecular weight compounds such as phthalocyanine compounds, indigo, thioindigo compounds, melocyanine compounds, cyanine compounds, and arylamine compounds, thiophene polymers, polymers and inorganic substances having an aryl amine group Material is possible. Spiro-OMeTAD as the low molecular compound

[2,2',7,7'-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene], m-MTDATA [4,4',4''-tris[(3 -methylphenyl)phenylamino]triphenylamine], ACR-TPA [4,4'-(10-(4-methoxyphenyl)-9,9-dimethyl-9,10-dihydroacridine-2,7-diyl)bis(N,N- bis(4-methoxyphenyl)aniline)], CzPF [9-(4-fluorophenyl)-3,6-bis(4,4′-dimethoxydiphenylaminyl)-carbazole] and the like may be mentioned arylamine-based compounds. Typical examples of the polymer material include PEDOT:PSS [poly(3,4-ethylenedioxythiophene):poly(4-styrene sulfonate)], G-PEDOT [poly(3,4-ethylenedioxythiophene):poly(4-styrene sulfonate): polyglycol(glycerol)], PANI:PSS[polyaniline:poly(4-styrene sulfonate)], PANI:CSA(polyaniline:camphor sulfonic acid), PDBT[poly(4,4'-dimethoxy bithophene)], P3HT(poly- 3-hexylthiophene), 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]], PCDTBT(poly-[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole -4,7-diyl-2,5-thiophenediyl]), PTAA [poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)] may be exemplified. Representative examples of the inorganic material include MoO ₃ , V ₂ O ₅ , NiO, WO ₃ , CuI, CuSCN, and CuPc [copper(II) phthalocyanine], but are not particularly limited thereto. Examples of the material for the hole transport layer include low molecular compounds, high molecular compounds, and inorganic substances, but these may additionally contain a dopant. These dopants play a role in improving hole transport characteristics, and include lithium bis (trifluoromethanesulfonyl) imide, silver bis (trifluoromethanesulfonyl) imide, N-butyl-N-(4-pyridylheptyl) imidazolium bis (trifluoromethane) sulfonimide, zinc bistrifluoro methane sulfonimide, tris(2-(1H-pyrazol-1-yl)pyridine)cobalt(III) tri(bis(trifluoromethane)sulfonimide, butylmethyl imidazolium iodide, 1-methyl-3-propylimidazolium iodide, lithium iodide, 4-tertbutylpyridine, etc. alone or It can be applied in multiple ways.

The hole transport layer of the present invention is characterized in that it contains the hole transport agent and a water resistance improving agent (a fluorine-containing aromatic compound having at least 6 or more fluorine atoms) such as the following general formula 1 or 2. In addition, the hole transport layer of the present invention is characterized in that it contains the hole transport agent, the dopant, and a water resistance improving agent (aromatic fluorine compound having at least 6 or more fluorine atoms) such as the following general formula 1 or 2.

[General Formula 1]

[General Formula 2]

In the general formula 1, X is selected from carbon (C), silicon (Si), germanium (Ge), and tin (Sn). Y is hydrogen; Halogen atom; Hydroxy group; Cyano group; A substituted or unsubstituted C1-C30 acetate group; A ketone group of substituted or unsubstituted C1-C30 (C1 means 1 carbon atom and C30 means 30 carbon atoms); A substituted or unsubstituted C1-C30 vinyl group; A substituted or unsubstituted C1-C30 alkoxy group; A substituted or unsubstituted C1-C30 alkyl group; A substituted or unsubstituted C1-C30 heteroalkyl group; A substituted or unsubstituted C1-C30 heteroalkoxy group; A substituted or unsubstituted C6-C30 aryl group; A substituted or unsubstituted C6-C30 arylalkyl group; A substituted or unsubstituted C6-C30 aryloxy group; A substituted or unsubstituted C2-C30 heteroaryl group; A substituted or unsubstituted C2-C30 heteroarylalkyl group; A substituted or unsubstituted C2-C30 heteroaryloxy group; A substituted or unsubstituted C5-C20 cycloalkyl group; A substituted or unsubstituted C2-C30 heterocycloalkyl group; A substituted or unsubstituted C1-C30 alkyl ester group; A substituted or unsubstituted C1-C30 heteroalkyl ester group; A substituted or unsubstituted C2-C30 aryl ester group; And it may be selected from the group consisting of a substituted or unsubstituted C2-C30 heteroaryl ester group. In the general formulas 1 and 2, Z ₁ and Z ₂ may be the same or different as a fluorine-substituted aromatic functional group, and bis (pentafluorophenyl) phosphinyl group, trifluoro thienyl group, trifluoro pyrrolyl group, tetrafluoro pyrrolyl group, tetrafluoro pridinyl group, It is selected from pentafluoro phenyl group, heptafluoro naphthyl group, nonafluoro anthracenyl group, nonafluoro biphenyl group, octafluoro carbazoyl group, octafluoro phenothiazinyl group, octafluoro phenoxazinyl group. In General Formula 1, n is selected from 1 to 10 as the number of XY ₂ groups connected. In the general formula 2, Me is selected from Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, Pd.

Representative examples of the water resistance improving agent (aromatic fluorine compound having at least 6 fluorine atoms) of the general formulas 1 and 2 of the present invention are shown below, but the present invention is not limited thereto.

As a method of forming the hole transport layer, a hole transport agent and the water resistance improving agent are dissolved in a solvent or dispersed in a dispersion medium, and then spin coating method, spray coating method, screen printing method, bar coating method, doctor blade coating method, It may be formed by an inkjet printing method, a slot die coating method, or the like, and may be formed by thermal evaporation or sputtering under vacuum. It is suitable if the thickness of the hole transport layer is about 5 to 300 nm. As the solvent or dispersion medium, benzene, toluene, xylene, chloroform, dichloromethane, carbon tetrachloride, chlorobenzene, and dichlorobenzene ), tertiary butyl alcohol, acetronitrile, tetrahydrofuran, ethanol, isopropyl alcohol, methanol, acetone, propanol (propanol), methylethylketone, butylalcohol, ethyl ether, dimethyl ether, water, formamide, N-methylformamide (N- methylformamide), N,N-dimethylformamide, acetamide, N-methylacetamide, N,N-dimethylacetamide, N-methylpropionamide, 2-pyrrolidone, N-methyl pyrrolidone, methyl sulfoxide, dimethyl sulfoxide, sulfur Phosphorane (sulfolane), diphenyl sulfone (diphenyl sulfone), and the like may be used alone or in plurality, and the present invention is not limited thereto.

As described above, the hole transport layer obtained by adding the water resistance improving agent to the hole transport agent has excellent water resistance by fluorine atoms, and has the advantage of preventing external moisture from penetrating into the perovskite compound. Therefore, it is possible to implement a long-life, highly reliable perovskite solar cell. On the other hand, the water resistance improving agent (general formula 1 or 2) of the present invention has a structure in which a fluorine-substituted aromatic functional group (Z ₁ or Z ₂ ) is arranged left and right by a linking group such as XY ₂ or Me. If the fluorine-substituted aromatic functional group (Z ₁ or Z ₂ ) is directly chemically bonded without a linking group such as XY ₂ or Me (Z ₁ -Z ₂ ), the molecule is very rigid and is not dissolved in a solvent or sublimated by heat. There is a problem that the transport layer formation process is difficult. As described above, since the water resistance improving agent of the present invention contains a linking group such as XY ₂ or Me, the flexibility of the molecule is excellent, and since it contains a large amount of fluorine atoms, the surface tension is very large. In this way, due to its excellent flexibility and high surface tension, the water-resistance improving agent partially migrates to the surface layer during the hole transport layer formation process. In other words, at the perovskite compound (P-type semiconductor)/hole transport layer interface, the concentration of the hole transport agent is higher than that of the water resistance improver, whereas at the hole transport layer/second electrode interface, the concentration of the water resistance enhancer is higher than that of the hole transport agent. . As a result, since the concentration of the water resistance enhancing agent (fluorine-containing aromatic compound) is locally increased on the surface of the hole transport layer, there is an advantage of further preventing the penetration of external moisture.

<Formation of the second electrode>

The second electrode formed on the hole transport layer plays a role of collecting holes (i.e., accepts holes from the hole transport layer), has high electrical conductivity, and is capable of ohmic bonding with the hole transport layer, and stability This should be excellent. Such materials for the second electrode include silver (Ag), platinum (Pt), tungsten (W), copper (Cu), molybdenum (Mo), gold (Au), nickel (Ni) having a relatively large work function. , Palladium (Pd), indium (In), ruthenium (Ru), rhodium (Rh), iridium (Ir), osmium (Os), conductive carbon, and conductive polymers are exemplified, and can be used alone or in plurality. . These metal electrodes can be formed by DC sputtering method, thermal evaporation, or otherwise, a wet method such as chemical vapor deposition (CVD), atomic layer deposition (ALD), electroplating and various printing technologies, and the thickness is about 0.1 to 5 μm. If it is, it is suitable.

Since the perovskite solar cell according to the present invention may be deteriorated by moisture and oxygen during operation, it is necessary to block each layer formed from the atmosphere through an encapsulation process. As an example of the encapsulation process, a moisture-absorbing agent is attached to the center of the protective cap made of glass or metal, and a sealing material is dispensed on the edge. Next, the fabricated device (substrate/first electrode/N-type semiconductor: P-type semiconductor: hole transport layer/second electrode) is placed on the dispensed sealing material, and then UV or heat is applied to cure the sealing material. If the sealing material is cured using UV, measures must be taken to prevent UV light from entering the photoactive layer, because the photoactive layer or the like may be deteriorated by UV. In addition, the encapsulation process may use a method of forming a multilayer thin film under vacuum (a method of forming a passivation layer). In the perovskite solar cell of the present invention implemented by the above structure and manufacturing process, a grid electrode may be additionally formed on the first electrode and/or the second electrode. The grid electrode is mainly composed of a metal contact layer and can be formed through an electron beam system or other method, and mainly Ni, Al, Ag, or the like can be used. In addition, an antireflection layer may be additionally formed inside or outside the transparent substrate. Silicon nitride (SiNx) is generally used as the antireflection layer, which functions to further increase the efficiency by reducing the reflection loss of sunlight incident on the solar cell, and the thickness is 600~ by electron beam evaporation method and chemical vapor deposition method (CVD). It can be used by forming about 1000Å.

As described above, according to the present invention, the hole transport layer including an aromatic compound (water resistance improving agent) having at least 6 fluorine atoms blocks moisture introduced from the outside, thereby implementing a perovskite solar cell having excellent water resistance.

The present invention relates to a perovskite solar cell and a manufacturing method thereof, characterized in that the hole transport layer of a perovskite solar cell is composed of a hole transport agent and an aromatic compound having 6 or more fluorine atoms, and has high water resistance. Since the possibility of exposure of the perovskite compound to moisture by the hole transport layer is low, there is an effect of realizing a long-life solar cell.

In addition, the fluorine-containing aromatic compound contained in the hole transport layer has an effect of improving the efficiency of a solar cell by improving hole transport characteristics.

1 is a view showing the structure of a conventional perovskite solar cell,
2 is a graph showing the change over time in the efficiency of a perovskite solar cell with and without an aromatic compound (water resistance improver) (Structural Formula 1) having a fluorine atom according to Example 1 according to the present invention,
3 is a graph showing a change over time in efficiency of a perovskite solar cell containing and without an aromatic compound (Structural Formula 10) according to Example 2 according to the present invention.

Hereinafter, the present invention is to be described in more detail by way of examples, but the present invention is not limited by the following examples.

Example One

First, a 0.15M titanium diisopropoxide bis (acetylacetonate) solution (solvent: 1-butanol) was prepared to form a blocking layer, and then spin-coated and dried on the top of the ultrasonically cleaned FTO substrate. This was repeated three times and then heat-treated at 500° C. for 20 minutes to form a blocking layer of TiO ₂ component. Then commercial (manufacturer: Solaronix, TiO ₂ Particle diameter: 20 nm) TiO ₂ After diluting the paste with ethanol, it was coated on the blocking layer by spin coating (3000 rpm, 30s), and heat-treated at 500° C. for 60 minutes to form an N-type semiconductor layer. A 1.0 M PbI ₂ solution (solvent: dimethylformamide) was spin-coated on the upper portion of the substrate on which TiO ₂ , an N-type semiconductor, was formed, and then dried, followed by a CH ₃ NH ₃ I solution (10 mg/mL, solvent: 2-propanol) for 60 seconds. During immersion, a perovskite compound, CH ₃ NH ₃ PbI ₃ (P-type semiconductor) was conjugated to the surface of TiO ₂ . To form a hole transport layer, spiro-OMeTAD (85mM), tert-butylpyridine and LiN (CF ₃ SO ₂ ) ₂ were dissolved in a chlorobenzene solvent, and then Structural Formula 1 was added as a water resistance improving agent (5 wt% compared to spiro-OMeTAD). After, a mixed solution was prepared. Using the mixed solution, a hole transport layer was formed by spin coating (300 rpm, 30 seconds) and drying on the top of the P-type semiconductor. A perovskite solar cell was manufactured by forming Ag as a second electrode on the hole transport layer to a thickness of 100 nm by a thermal evaporation method. Meanwhile, a perovskite solar cell that does not contain a water resistance enhancer (Structural Formula 1) was also manufactured to determine whether or not the reliability was improved according to the presence or absence of a fluorine compound. At this time, the fabricated solar cell did not proceed with a separate encapsulation process to avoid contact with moisture in the atmosphere, and the photoelectric conversion efficiency was measured by irradiating light in the AM 1.5 condition (100mW/cm ² ) to the device. In the case of a solar cell containing Structural Formula 1, which is a fluorine-containing aromatic compound (water resistance improving agent), V _OC (open circuit voltage) is 1.05V, J _SC (short circuit current density) is 21.73 mA/cm ² and the fill factor is 71.09%. It was measured, and as a result, the photoelectric conversion efficiency of 16.22% was recorded.

In addition, in the case of a solar cell that does not contain Structural Formula 1, which is a fluorine-containing aromatic compound (water resistance improving agent), V _OC is 1.02 V , J _SC is 20.27 mA/cm ² and Fill Factor is 70.14%, which is 14.50% of photoelectric conversion. The efficiency was recorded, and the efficiency was lower than that of a device containing a fluorine-containing aromatic compound (water resistance improving agent). In addition, the fabricated solar cell was left in an atmosphere with a relative humidity of 35% to measure the efficiency of the solar cell according to the leaving time, and the results are presented in FIG. From FIG. 2, it was confirmed that the reduction in the efficiency of the perovskite solar cell including Structural Formula 1, which is a fluorine-containing aromatic compound (water resistance improving agent), is more gentle than the case where it is not included. From this, it was confirmed that Structural Formula 1, which is a fluorine-containing aromatic compound (water resistance improving agent), can improve the reliability of a perovskite solar cell.

Example 2

First, after dissolving (50mM) poly(3-hexylthiophene) in dichlorobenzene solvent, Structural Formula 10 was added as a fluorine-containing aromatic compound (a water resistance improving agent) [7wt% of poly(3-hexylthiophene)] A mixed solution for forming a transport layer was prepared. Perovskite solar cell [ V _OC = 1.12V, J _SC under the same conditions as in Example 1, except that the mixed solution was used to form the hole transport layer. = 19.87mA/cm ² , Fill Factor = 70.89%, Efficiency = 15.78%] was prepared. In addition, perovskite solar cells that do not contain a fluorine-containing aromatic compound (Structural Formula 10), which is a water resistance improving agent, are used in order to determine whether the reliability is improved according to the presence or absence of fluorine compounds [ V _OC = 0.98V, J _SC = 20.01mA/cm ² , Fill Factor = 68.75%, Efficiency = 13.48%] were also prepared. The fabricated solar cell was measured for photoelectric conversion efficiency under the AM 1.5 condition (100mW/cm ² ), and the change of efficiency over time (Fig. 3) was observed while changing the waiting time in the air. As can be seen from FIG. 3, it was confirmed that the reduction in efficiency of the perovskite solar cell including Structural Formula 10, which is a fluorine-containing aromatic compound, in the hole transport layer is gentler than the case where it is not included. From this, it was confirmed that Structural Formula 10, which is a fluorine-containing aromatic compound, can improve the reliability of a perovskite solar cell.

Example 3

First, PTAA [poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)] was dissolved (15mM) in xylene solvent, and then Structural Formula 11 was added as a fluorine-containing aromatic compound as a water resistance enhancer [PTAA 2wt%] to prepare a mixed solution for forming a hole transport layer. A perovskite solar cell [ V _OC = 1.08V, J _SC] under the same conditions as in Example 1, except that the mixed solution was used to form the hole transport layer. = 18.98mA/cm ² , Fill Factor = 71.02%, Efficiency = 14.56%] was prepared. In addition, perovskite solar cells that do not contain fluorine-containing aromatic compounds (Structural Formula 11) [ V _OC = 1.10V, J _SC] to determine whether reliability is improved according to the presence or absence of fluorine compounds. = 17.23mA/cm ² , Fill Factor = 70.38%, Efficiency = 13.34%] were also prepared. The photoelectric conversion efficiency of the manufactured solar cell was measured under the condition of AM 1.5 (100mW/cm ² ), and the change in efficiency with time was observed while changing the waiting time in the air. The perovskite solar cell including Structural Formula 11, which is a fluorine-containing aromatic compound, in the hole transport layer recorded 89% of the initial efficiency when left in the air for 72 hours. On the other hand, a perovskite solar cell that does not contain Structural Formula 11, which is a fluorine-containing aromatic compound, in the hole transport layer was measured to be 72% of the initial efficiency when left in the air for 89 hours. From this, it was confirmed that Structural Formula 11, which is a fluorine-containing aromatic compound, can improve the reliability of a perovskite solar cell.

Example 4

First, PCPDTBT [poly-[2,1,3-benzothiadiazole-4,7-diyl[4,4-bis(2-ethylhexyl)-4H-cyclopenta[2,1-b:3] in N,N-dimethylformamide solvent. ,4-b']dithiophene-2,6-diyl]] was dissolved (30mM), and Structural Formula No. 13 was added [13wt% compared to PCPDTBT] as a fluorine-containing aromatic compound as a water resistance improving agent to prepare a mixed solution for forming a hole transport layer. Was prepared. A perovskite solar cell was manufactured under the same conditions as in Example 1, except that the mixed solution was used to form the hole transport layer. In addition, a perovskite solar cell that does not contain a fluorine-containing aromatic compound (Structural Formula 13) was also manufactured in order to determine whether the reliability is improved according to the presence or absence of a fluorine compound. The photoelectric conversion efficiency of the manufactured solar cell was measured under the condition of AM 1.5 (100mW/cm ² ), and the change in efficiency with time was observed while changing the waiting time in the air. The perovskite solar cell containing Structural Formula 13, which is a fluorine-containing aromatic compound, in the hole transport layer recorded 91% of the initial efficiency when left in the air for 72 hours. On the other hand, the perovskite solar cell that does not contain Structural Formula 13, which is a fluorine-containing aromatic compound, in the hole transport layer was measured to be 69% of the initial efficiency when left in the air for 89 hours. From this, it was confirmed that Structural Formula 13, which is a fluorine-containing aromatic compound, can improve the reliability of a perovskite solar cell.

Example 5

First, m-MTDATA [4,4',4''-tris[(3-methylphenyl)phenylamino]triphenylamine] was dissolved (50mM) in a chloroform solvent, and then Structural Formula No. 15 was added as a fluorine-containing aromatic compound, which is a water resistance enhancer. [9wt% compared to m-MTDATA] to prepare a mixed solution for forming a hole transport layer. A perovskite solar cell was manufactured under the same conditions as in Example 1, except that the mixed solution was used to form the hole transport layer. In addition, a perovskite solar cell that does not contain a fluorine-containing aromatic compound (Structural Formula 15) was also manufactured in order to determine whether the reliability is improved according to the presence or absence of a fluorine compound. The photoelectric conversion efficiency of the manufactured solar cell was measured under the condition of AM 1.5 (100mW/cm ² ), and the change in efficiency with time was observed while changing the waiting time in the air. The perovskite solar cell containing Structural Formula 15, which is a fluorine-containing aromatic compound, in the hole transport layer recorded 88% of the initial efficiency when left in the air for 72 hours. On the other hand, the perovskite solar cell that does not contain Structural Formula 15, which is a fluorine-containing aromatic compound, in the hole transport layer was measured to be 73% of the initial efficiency when left in the air for 89 hours. From this, it was confirmed that Structural Formula 15, which is a fluorine-containing aromatic compound, can improve the reliability of a perovskite solar cell.

Example 6

First, in an acrylonitrile solvent, ACR-TPA [4,4'-(10-(4-methoxyphenyl)-9,9-dimethyl-9,10-dihydroacridine-2,7-diyl)bis(N,N-bis(4 -methoxyphenyl)aniline)] was dissolved (15mM), and Structural Formula 23 was added [5wt% compared to ACR-TPA] as a fluorine-containing aromatic compound as a water resistance improving agent to prepare a mixed solution for forming a hole transport layer. A perovskite solar cell was manufactured under the same conditions as in Example 1, except that the mixed solution was used to form the hole transport layer. In addition, a perovskite solar cell that does not contain a fluorine-containing aromatic compound (Structural Formula 23) was also manufactured in order to determine whether or not the reliability is improved according to the presence or absence of a fluorine compound. The photoelectric conversion efficiency of the manufactured solar cell was measured under the condition of AM 1.5 (100mW/cm ² ), and the change in efficiency with time was observed while changing the waiting time in the air. The perovskite solar cell containing Structural Formula 23, which is a fluorine-containing aromatic compound, in the hole transport layer recorded 88% of the initial efficiency when left in the air for 72 hours. On the other hand, the perovskite solar cell that does not contain Structural Formula 23, which is a fluorine-containing aromatic compound, in the hole transport layer was measured to be 73% of the initial efficiency when left in the air for 89 hours. From this, it was confirmed that Structural Formula 23, which is a fluorine-containing aromatic compound, can improve the reliability of a perovskite solar cell.

Example 7

In the solar cell manufacturing process presented in Example 1, all conditions were the same as in Example 1, except that Structural Formula 26 (0.5 wt% compared to spiro-OMeTAD) was used as a fluorine-containing aromatic compound as a water resistance improving agent. A Lobsky solar cell was manufactured. In addition, a perovskite solar cell that does not contain Structural Formula No. 26 was also prepared to investigate water resistance characteristics. The photoelectric conversion efficiency of the manufactured solar cell was measured under the condition of AM 1.5 (100mW/cm ² ), and the change in efficiency with time was observed while changing the waiting time in the air. The perovskite solar cell containing Structural Formula 26, which is a fluorine-containing aromatic compound, in the hole transport layer recorded 90% of the initial efficiency when left in the air for 72 hours. On the other hand, the perovskite solar cell that does not contain Structural Formula 26, which is a fluorine-containing aromatic compound, in the hole transport layer was measured to be 77% of the initial efficiency when left in the air for 89 hours. From this, it was confirmed that Structural Formula 26, which is a fluorine-containing aromatic compound, can improve the reliability of a perovskite solar cell.

Example 8

In the solar cell manufacturing process presented in Example 1, all conditions were the same as in Example 1, except that Structural Formula 27 (7wt% compared to spiro-OMeTAD) was used as a fluorine-containing aromatic compound as a water resistance improving agent. A skyt solar cell was manufactured. In addition, a perovskite solar cell that does not contain Structural Formula No. 26 was also prepared to investigate water resistance characteristics. The photoelectric conversion efficiency of the manufactured solar cell was measured under the condition of AM 1.5 (100mW/cm ² ), and the change in efficiency with time was observed while changing the waiting time in the air. The perovskite solar cell containing Structural Formula 27, which is a fluorine-containing aromatic compound, in the hole transport layer recorded 87% of the initial efficiency when left in the air for 72 hours. On the other hand, a perovskite solar cell that does not contain Structural Formula 27, which is a fluorine-containing aromatic compound, in the hole transport layer was measured to be 78% of the initial efficiency when left in the air for 89 hours. From this, it was confirmed that Structural Formula 27, which is a fluorine-containing aromatic compound, can improve the reliability of a perovskite solar cell.

Claims (11)

Board; A first electrode formed on the substrate; A photoactive layer formed on the first electrode and made of an N-type semiconductor and a P-type semiconductor; A hole transport layer formed on the photoactive layer; In the perovskite solar cell comprising a second electrode formed on the hole transport layer,
The hole transport layer includes a hole transport agent and 6 or more fluorine atoms in a molecule, and a fluorine-containing aromatic compound represented by the following general formula 1 or 2 is composed of singly or plural fluorine-containing aromatic compounds. Lobsky solar cell.
[General Formula 1]

[General Formula 2]

In the general formula 1,
X is selected from carbon (C), silicon (Si), germanium (Ge) and tin (Sn).
Y is hydrogen; Halogen atom; Hydroxy group; Cyano group; A substituted or unsubstituted C1-C30 acetate group; A ketone group of substituted or unsubstituted C1-C30 (C1 means 1 carbon atom and C30 means 30 carbon atoms); A substituted or unsubstituted C1-C30 vinyl group; A substituted or unsubstituted C1-C30 alkoxy group; A substituted or unsubstituted C1-C30 alkyl group; A substituted or unsubstituted C1-C30 heteroalkyl group; A substituted or unsubstituted C1-C30 heteroalkoxy group; A substituted or unsubstituted C5-C20 cycloalkyl group; A substituted or unsubstituted C2-C30 heterocycloalkyl group; A substituted or unsubstituted C1-C30 alkyl ester group; At least one type is selected from the group consisting of substituted or unsubstituted C1-C30 heteroalkyl ester groups.
In the general formulas 1 and 2, Z ₁ and Z ₂ may be the same or different as a fluorine-substituted aromatic functional group, and bis (pentafluorophenyl) phosphinyl group, trifluoro thienyl group, trifluoro pyrrolyl group, tetrafluoro pyrrolyl group, tetrafluoro pridinyl group, At least one is selected from pentafluoro phenyl group, heptafluoro naphthyl group, nonafluoro anthracenyl group, nonafluoro biphenyl group, octafluoro carbazoyl group, octafluoro phenothiazinyl group, and octafluoro phenoxazinyl group.
In General Formula 1, n is selected from 1 to 10 as the number of XY ₂ groups connected.
In the general formula 2, Me is selected from Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, Pd.
The method according to claim 1,
The substrate is a perovskite solar cell having a hole transport layer having a high water resistance, characterized in that selected from optically transparent glass and plastic.
The method according to claim 1,
The first electrode is FTO (F-doped tin oxide), ITO (In-doped tin oxide), IZO (In-doped zinc oxide), ZnO-Ga ₂ O ₃ , ZnO-Al ₂ O ₃ , SnO ₂ -Sb A perovskite solar cell having a hole transport layer having high water resistance, characterized in that it is one selected from ₂ O ₃ .
The method according to claim 1,
The material for the N-type semiconductor is a highly water-resistant hole transport layer, characterized in that it is selected alone or in plurality from TiO ₂ , Al ₂ O ₃ , SnO ₂ , ZnO, WO ₃ , Nb ₂ O ₅ , TiSrO ₃ , ZrO ₂ With perovskite solar cell.
The method according to claim 1,
The P-type semiconductor is RMX ₃ [where R is C _n H _{2n + 1} NH ₃ ⁺ (n is an integer of 1 to 9), NH ₄ ⁺ , HC(NH ₂ ) ₂ ⁺ , Cs ⁺ , NF ₄ ⁺ , NCl ₄ ⁺ , PF ₄ ⁺ , PCl ₄ ⁺ , CH ₃ PH ₃ ⁺ , CH ₃ AsH ₃ ⁺ , CH ₃ SbH ₃ ⁺ , PH ₄ ⁺ , AsH ₄ ⁺ , SbH ₄ ⁺ and combinations thereof It is a monovalent cation that is, M ²⁺ is Pb, Sn ^{+ 2,} Ge ^{2 +} and means that the divalent metal cation is selected from the group consisting of the combinations thereof, and, X is ^{F -, Cl -, Br -} , I ^- the means halogen anion] having a high hole-transport layer of water-resistant, characterized in that which is selected as a sole or a plurality from a compound represented by perovskite solar cells.
The method according to claim 1,
The hole transport agent is Spiro-OMeTAD [2,2',7,7'-tetrakis-(N,N-di-4-methoxyphenylamino)-9,9'-spirobifluorene], m-MTDATA [4,4', 4''-tris[(3-methylphenyl)phenylamino]triphenylamine], ACR-TPA [4,4'-(10-(4-methoxyphenyl)-9,9-dimethyl-9,10-dihydroacridine-2,7- diyl)bis(N,N-bis(4-methoxyphenyl)aniline)], CzPF [9-(4-fluorophenyl)-3,6-bis(4,4′-dimethoxydiphenylaminyl)-carbazole] drylamine compound, PEDOT :PSS [poly(3,4-ethylenedioxythiophene):poly(4-styrene sulfonate)], G-PEDOT [poly(3,4-ethylenedioxythiophene):poly(4-styrene sulfonate):polyglycol(glycerol)], PANI: PSS[polyaniline:poly(4-styrene sulfonate)], PANI:CSA(polyaniline:camphor sulfonic acid), PDBT[poly(4,4'-dimethoxy bithophene)], P3HT(poly-3-hexylthiophene), 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]], PCDTBT(poly-[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2 ,5-thiophenediyl]), of PTAA [poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine)] A film having a high water resistance hole transport layer, characterized in that it is selected singly or in plurality from inorganic materials such as polymer compounds, MoO ₃ , V ₂ O ₅ , NiO, WO ₃ , CuI, CuSCN, CuPc [copper(II) phthalocyanine] Lobsky solar cell.
The method according to claim 1,
A dopant may be additionally included in the hole transport layer, and the dopant is lithium bis (trifluoromethanesulfonyl) imide, silver bis (trifluoromethanesulfonyl)imide, N-butyl-N-(4-pyridylheptyl)imidazolium bis (trifluoromethane) sulfonimide, zinc bistrifluoro methane sulfonimide, tris(2-(1H-pyrazol-1-yl)pyridine)cobalt(III) tri[bis(trifluoromethane)sulfonimide, butylmethyl imidazolium iodide, 1-methyl-3-propylimidazolium iodide, lithium iodide, 4-tertbutylpyridine Or a perovskite solar cell having a high water resistance hole transport layer, characterized in that a plurality of selected.
The method according to claim 1,
The second electrode includes silver (Ag), platinum (Pt), tungsten (W), copper (Cu), molybdenum (Mo), gold (Au), nickel (Ni), indium (In), and ruthenium ( Ru), palladium (Pd), rhodium (Rh), iridium (Ir), osmium (Os), a P having a high water resistance hole transport layer, characterized in that it is selected alone or in plurality from conductive polymers composed of conductive carbon. Lobsky solar cell.
The method according to claim 1,
A blocking layer is additionally included between the first electrode and the photoactive layer, and the material for the blocking layer is selected from TiO ₂ and ZnO alone or in plurality.Perovskite solar cell having a high water resistance hole transport layer.
Forming a first electrode on the substrate;
Forming a photoactive layer made of an N-type semiconductor and a P-type semiconductor on the first electrode;
Forming a hole transport layer on the photoactive layer;
In the solar cell manufacturing process comprising the step of forming a second electrode on the hole transport layer,
The hole transport layer includes a hole transport agent and 6 or more fluorine atoms in a molecule, and a fluorine-containing aromatic compound represented by the following general formula 1 or 2 is composed of singly or plural fluorine-containing aromatic compounds. Manufacturing method of Lobsky solar cell.

[General Formula 1]

[General Formula 2]

In the general formula 1,
X is selected from carbon (C), silicon (Si), germanium (Ge) and tin (Sn).
Y is hydrogen; Halogen atom; Hydroxy group; Cyano group; A substituted or unsubstituted C1-C30 acetate group; A ketone group of substituted or unsubstituted C1-C30 (C1 means 1 carbon atom and C30 means 30 carbon atoms); A substituted or unsubstituted C1-C30 vinyl group; A substituted or unsubstituted C1-C30 alkoxy group; A substituted or unsubstituted C1-C30 alkyl group; A substituted or unsubstituted C1-C30 heteroalkyl group; A substituted or unsubstituted C1-C30 heteroalkoxy group; A substituted or unsubstituted C5-C20 cycloalkyl group; A substituted or unsubstituted C2-C30 heterocycloalkyl group; A substituted or unsubstituted C1-C30 alkyl ester group; At least one type is selected from the group consisting of substituted or unsubstituted C1-C30 heteroalkyl ester groups.
In the general formulas 1 and 2, Z ₁ and Z ₂ may be the same or different as a fluorine-substituted aromatic functional group, and bis (pentafluorophenyl) phosphinyl group, trifluoro thienyl group, trifluoro pyrrolyl group, tetrafluoro pyrrolyl group, tetrafluoro pridinyl group, At least one is selected from pentafluoro phenyl group, heptafluoro naphthyl group, nonafluoro anthracenyl group, nonafluoro biphenyl group, octafluoro carbazoyl group, octafluoro phenothiazinyl group, and octafluoro phenoxazinyl group.
In General Formula 1, n is selected from 1 to 10 as the number of XY ₂ groups connected.
In the general formula 2, Me is selected from Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, Pd. The method of claim 10,
The method of manufacturing a perovskite solar cell having a high water resistance hole transport layer, characterized in that it further comprises the step of forming a blocking layer between the step of forming the first electrode and the step of forming the photoactive layer.

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