Perovskite solar cell and manufacturing method thereof

Abstract

The present invention relates to a perovskite solar cell in which a three-layered electron transport buffer layer is introduced between a perovskite light absorbing layer and an electron transport layer, and a manufacturing method thereof. The three-layered electron transport buffer layer is a structure in which a passivation buffer layer, a carbon-based electron transport layer, and a hole blocking buffer layer are sequentially stacked, and prevents the migration of holes to the electron transport layer, improving the selective transport of electrons. This minimizes performance degradation of the perovskite solar cell and ensures stability.

Description

[Technical Field]

[0001] The present invention relates to a perovskite solar cell in which a three-layer electron transport buffer layer is introduced between a perovskite light-absorbing layer and an electron transport layer, and a method for manufacturing the same. [Background technology]

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

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

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

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

[0006] Recently, perovskite solar cells have been developed that use the perovskite-structured halide compound (NH3CH3)PbX3 (X = I, Br, Cl) as the photoactive material, and research is underway for commercialization. The general structural formula of perovskite is the ABX3 structure, with anions located at the X site, large cations located at the A site, and small cations located at the B site.

[0007] Perovskite solar cells are currently being developed as either pin-type perovskite single solar cells or two-terminal perovskite / silicon tandem solar cells. In the case of two-terminal perovskite / silicon tandem solar cells, a recombination layer is formed on the glass and lower silicon solar cell, and then the upper perovskite solar cell layers - the hole transport layer, perovskite light absorption layer, electron transport layer, and transparent electrode - are sequentially formed to create a two-terminal perovskite / silicon tandem solar cell. In this process, electrons and holes separated from the perovskite light absorption layer are transported to the electron transport layer and hole transport layer, respectively.

[0008] Holes separated from the perovskite light-absorbing layer do not move only to the lower hole transport layer, but also to the upper electron transport layer. In this case, charge recombination occurs at the interface of the electron transport layer due to the mismatch in energy levels, which reduces the performance of the solar cell.

[0009] Furthermore, when forming the electron transport layer, the atomic layer does not grow uniformly during the initial nucleus growth stage, making it difficult to form a uniform ultra-thin film. This not only reduces the performance of the solar cell, but also reduces the reproducibility and stability of the solar cell due to unstable thin film formation caused by reduced interface uniformity. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been devised to overcome the above-mentioned problems, and aims to provide a perovskite solar cell and a manufacturing method thereof that introduces a three-layer electron transport buffer layer between a perovskite light absorption layer and an electron transport layer, thereby preventing the movement of holes to the electron transport layer and improving the selective transport of electrons, thereby minimizing performance degradation of the perovskite solar cell and ensuring stability. [Means for solving the problem]

[0011] In order to solve the above problems, the perovskite solar cell of the present invention includes a stacked body in which a hole transport layer, a perovskite light absorption layer, an electron transport layer, a transparent electrode, and a metal electrode are stacked in order, and an electron transport buffer layer may be formed between the perovskite light absorption layer and the electron transport layer.

[0012] In a preferred embodiment of the present invention, the electron transport buffer layer may contain one or more selected from lithium fluoride (LiF), magnesium fluoride (MgF), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF), aluminum oxide (AlO), and calcium fluoride (CaF).

[0013] In a preferred embodiment of the present invention, the electron transport buffer layer may have a structure in which a passivation buffer layer, a carbon-based electron transport layer, and a hole blocking buffer layer are sequentially stacked.

[0014] In a preferred embodiment of the present invention, a passivation buffer layer may be laminated on one side of the perovskite light-absorbing layer, and the hole-blocking buffer layer may be laminated on one side of the electron transport layer.

[0015] In a preferred embodiment of the present invention, the passivation buffer layer may contain one or more selected from lithium fluoride (LiF), magnesium fluoride (MgF), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF), aluminum oxide (AlO), and calcium fluoride (CaF).

[0016] In a preferred embodiment of the present invention, the hole-blocking buffer layer may contain one or more selected from lithium fluoride (LiF), magnesium fluoride (MgF), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF), aluminum oxide (AlO), and calcium fluoride (CaF).

[0017] In one preferred embodiment of the present invention, the carbon-based electron transport layer may comprise a fullerene-based organic material.

[0018] In a preferred embodiment of the present invention, the fullerene-based organic material is C 60 , C 70 , PC60BM, and PC70BM.

[0019] In a preferred embodiment of the present invention, the carbon-based electron transport layer and the passivation buffer layer may have a thickness ratio of 1:0.01 to 0.2.

[0020] In a preferred embodiment of the present invention, the carbon-based electron transport layer and the hole-blocking buffer layer may have a thickness ratio of 1:0.01-0.2.

[0021] In a preferred embodiment of the present invention, the passivation buffer layer may have an average thickness of 0.5 to 5 nm.

[0022] In a preferred embodiment of the present invention, the hole-blocking buffer layer may have an average thickness of 0.5 to 5 nm.

[0023] In one preferred embodiment of the present invention, the carbon-based electron transport layer may have an average thickness of 3 to 30 nm.

[0024] In a preferred embodiment of the present invention, the electron transport layer and the electron transport buffer layer may have a thickness ratio of 1:1.1 to 2.4.

[0025] In a preferred embodiment of the present invention, the electron transport layer may have an average thickness of 3 to 30 nm.

[0026] In a preferred embodiment of the present invention, the perovskite solar cell of the present invention may be a pin structure perovskite solar cell, a nip inverted structure perovskite solar cell, a tandem perovskite solar cell or a tandem silicon / perovskite heterojunction solar cell.

[0027] The method for manufacturing a perovskite solar cell of the present invention includes a first step of forming a perovskite light-absorbing layer on top of a hole-transporting layer, a second step of forming an electron-transporting buffer layer on top of the perovskite light-absorbing layer through a vapor deposition process or a solution process, and a third step of sequentially forming an electron-transporting layer, a transparent electrode, and a metal electrode on top of the electron-transporting buffer layer, wherein the electron-transporting buffer layer may include one or more selected from the group consisting of lithium fluoride (LiF), magnesium fluoride (MgF), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF), aluminum oxide (AlO), and calcium fluoride (CaF).

[0028] In a preferred embodiment of the present invention, the second step may include: Step 2-1 of forming a passivation buffer layer on the perovskite light-absorbing layer through a vapor deposition process or a solution process; Step 2-2 of forming a carbon-based electron transport layer on the passivation buffer layer through a vapor deposition process or a solution process; and Step 2-3 of forming a hole-blocking buffer layer on the carbon-based electron transport layer through a vapor deposition process or a solution process.

[0029] Furthermore, the tandem silicon / perovskite heterojunction solar cell of the present invention is a heterojunction solar cell in which a solar cell, a transparent conductive layer, a hole transport layer, a perovskite light absorbing layer, an electron transport buffer layer, an electron transport layer, a transparent electrode, and a metal electrode are sequentially stacked, and the electron transport buffer layer may contain one or more selected from lithium fluoride (LiF), magnesium fluoride (MgF), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF), aluminum oxide (AlO), and calcium fluoride (CaF).

[0030] In a preferred embodiment of the present invention, the solar cell may be a polycrystalline silicon solar cell, a crystalline silicon solar cell, a perovskite solar cell, a gallium arsenide (GaAs) solar cell, a cadmium telluride (CdTe) solar cell, a CIGS (CuInGaSe) solar cell, a CZTS (CuZnSnS) solar cell, an organic solar cell, a dye-sensitized solar cell, or a III-V compound solar cell. [Effects of the Invention]

[0031] The perovskite solar cell of the present invention incorporates a three-layer electron transport buffer layer between the perovskite light absorption layer and the electron transport layer, thereby forming a physical barrier, imparting physical passivation properties, and improving hole blocking properties, thereby reducing the occurrence of shunts within the solar cell and increasing shunt resistance, thereby improving the fill factor (FF) and the performance of the solar cell. [Brief explanation of the drawings]

[0032] [Figure 1] FIG. 1 is a cross-sectional view showing an electron transport buffer layer according to a preferred embodiment of the present invention. [Figure 2] FIG. 2 is a graph showing the current density as a function of applied voltage for each of the tandem silicon / perovskite heterojunction solar cells produced in Examples 1 to 3. DETAILED DESCRIPTION OF THE INVENTION

[0033] The present invention will now be described in more detail.

[0034] In conventional perovskite solar cells, holes separated from the perovskite light absorption layer do not move only to the lower hole transport layer, but also to the upper electron transport layer. In this case, charge recombination occurs at the interface of the electron transport layer due to energy level mismatch, resulting in a problem of reduced solar cell performance.

[0035] Furthermore, when forming an electron transport layer, the atomic layer does not grow uniformly during the initial nucleus growth stage, making it difficult to form a uniform ultra-thin film. This not only reduces the performance of the solar cell, but also reduces the reproducibility and stability of the solar cell due to unstable thin film formation caused by reduced interface uniformity.

[0036] Therefore, the present invention relates to a perovskite solar cell that prevents the movement of holes to the electron transport layer and improves the selective transport of electrons by introducing a three-layer electron transport buffer layer between the perovskite light absorption layer and the electron transport layer, thereby minimizing performance degradation of the perovskite solar cell and ensuring stability.

[0037] The perovskite solar cell of the present invention may be a pin structure perovskite solar cell, an nip inverted structure perovskite solar cell, a tandem perovskite solar cell, or a tandem silicon / perovskite heterojunction solar cell, preferably a tandem silicon / perovskite heterojunction solar cell, or may be a solar cell including a stack in which a hole transport layer (HTL or hole transport layer), a perovskite light absorption layer, an electron transport layer (ETL), a transparent electrode, and a metal electrode are stacked in this order.

[0038] Furthermore, the perovskite solar cell of the present invention may have an electron transport buffer layer formed between the perovskite light-absorbing layer and the electron transport layer.

[0039] In a preferred embodiment, when the perovskite solar cell of the present invention is a tandem silicon / perovskite heterojunction solar cell, it may be a heterojunction solar cell in which a solar cell, a transparent conductive layer, a hole transport layer, a perovskite light absorbing layer, an electron transport buffer layer, an electron transport layer, a transparent electrode, and a metal electrode are sequentially stacked.

[0040] The solar cell may be a polycrystalline silicon solar cell, a crystalline silicon solar cell, a perovskite solar cell, a gallium arsenide (GaAs) solar cell, a cadmium telluride (CdTe) solar cell, a CIGS (CuInGaSe) solar cell, a CZTS (CuZnSnS) solar cell, an organic solar cell, a dye-sensitized solar cell, or a III-V compound solar cell.

[0041] Furthermore, the thickness of the solar cell is not particularly limited, but may preferably be 140 to 250 μm, more preferably 160 to 200 μm.

[0042] The transparent conductive layer is a layer that induces the recombination of electrons and holes generated in the solar cell and the perovskite light absorption layer described below, and can be a transparent thin film deposited with ITO (Indium Tin Oxide), FTO (Fluorine-doped Tin Oxide), ATO (Sb2O3-doped Tin Oxide), GTO (Gallium-doped Tin Oxide), ZTO (tin-doped zinc oxide), ZTO:Ga (gallium-doped ZTO), IGZO (Indium gallium zinc oxide), IZO (Indium-doped zinc oxide), or AZO (Aluminum-doped zinc oxide).

[0043] As an example of forming a transparent conductive layer, when a silicon solar cell doped with n- or p-type impurities is used as the solar cell, the silicon solar cell doped with n- or p-type impurities may be treated with hydrofluoric acid to remove the SiOx oxide film, and then the remaining hydrofluoric acid may be removed using ultrapure water. After that, a transparent conductive layer may be formed on the silicon solar cell from which the oxide film has been removed through a sputtering process.

[0044] Furthermore, the thickness of the transparent conductive layer is not particularly limited, but may preferably be 5 nm to 50 nm, and more preferably 15 nm to 25 nm.

[0045] The hole transport layer (HTL) is a layer that transports holes formed in the perovskite light-absorbing layer (described later) and simultaneously blocks the movement of electrons, and may contain an inorganic and / or organic hole transport material.

[0046] In this case, the inorganic hole transport material may include at least one selected from nickel oxide (NiOx), CuSCN, CuCrO2, CuI, MoO, and V2O5.

[0047] Examples of organic hole transport materials include 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), F16CuP C(copper(II)1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro-29H, 31H-phthalocyanine), SubPc(boron N3(cis-di(thiocyanato)-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)-ruthenium(II), P3HT(poly[3-hexylthiophene]), MDMO-PPV(poly[2-methoxy-5-(3',7'-dimethyloctyloxyl)]-1,4-phenylene vinylene)、MEH-PPV(poly[2-methoxy-5-(2’’-ethylhexyloxy)-p-phenylene vinylene])、P3OT(poly(3-octyl thiophene))、POT(poly(octyl thiophene))、P3DT(poly(3-decyl thiophene))、P3DDT(poly(3-dodecyl thiophene)、PPV(poly(p-phenylene vinylene))、TFB(poly(9,9’-dioctylfluorene-co-N-(4-butylphenyl)diphenyl amine)、ポリアニリン(Polyaniline)、Spiro-MeOTAD([2,22’,7,77’-tetrkis(N,N-di-pmethoxyphenyl amine)-9,9,9’-spirobi fluorine])、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 contain one or more selected from poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate), PTAA (poly(triarylamine)), 2-PACz, MeO-2PACz, Br-2PACz, Me-4PACz, MeO-4PACz, and 6-PACz.

[0048] The hole transport layer can be formed by coating or vacuum deposition, and the coating method can be gravure coating, bar coating, printing, spraying, spin coating, dipping, or die coating.

[0049] The thickness of the hole transport layer is not particularly limited, but may preferably be 5 nm to 40 nm, and more preferably 10 nm to 30 nm.

[0050] The perovskite light absorbing layer may include a common perovskite material that is applied to the light absorbing layer of a solar cell, and a preferred example thereof may include a perovskite material represented by the following Chemical Formula 1:

[0051] [ka] In Formula 1, C is a monovalent cation, which may include amines, ammonium, Group 1 metals, Group 2 metals, and / or other cations or cation-like compounds, preferably formamidinium (FA), methylammonium (MA), FAMA, CsFAMA, CsFA, or N(R)4. + (wherein R may be the same group or different groups, and R may be a linear alkyl group having 1 to 5 carbon atoms, a branched alkyl group having 3 to 5 carbon atoms, a phenyl group, an alkylphenyl group, an alkoxyphenyl group, or an alkyl halide).

[0052] Furthermore, M in Chemical Formula 1 is a divalent cation and may include one or two selected from Fe, Co, Ni, Cu, Sn, Pb, Bi, Ge, Ti, Eu, and Zr.

[0053] Furthermore, X in Chemical Formula 1 is a monovalent anion and may include one or more halide elements and / or Group 16 anions selected from F, Cl, Br, and I. In a preferred example, X is I x Br 3-x (0≦x≦3).

[0054] In a preferred embodiment of Chemical Formula 1, FAPbI x Br 3-x (0≦x≦3), MAPbI x Br 3-x (0≦x≦3), CSFAPbI x Br 3-x (0≦x≦3), CSMAFAPbI x Br 3-x (0≦x≦3), CH3NH3PbX3 (X=Cl, Br, I, BrI2 or Br2I), CH3NH3SnX3 (X=Cl, Br or I), CH(═NH)NH3PbX3 (X=Cl, Br, I, BrI2 or Br2I) or CH(═NH)NH3SnX3 (X=Cl, Br or I).

[0055] In the perovskite solar cell of the present invention, the perovskite light-absorbing layer may be a single layer made of the same perovskite material, or may have a multilayer structure in which multiple layers made of different perovskite materials are stacked.The light-absorbing layer made of one type of perovskite material may contain the one type of perovskite material having a pillar shape such as a columnar, plate, needle, wire, or rod, and another different type of perovskite material.

[0056] Examples of methods for forming the perovskite light-absorbing layer include coating methods and vacuum deposition methods. Examples of coating methods include gravure coating, bar coating, printing, spraying, spin coating, dipping, inkjet coating, and die coating.

[0057] Referring to FIG. 1, the electron transport buffer layer 10 can be formed on the top of the perovskite light absorbing layer through a deposition process or a solution process.

[0058] In this case, the deposition may be performed by a common deposition process used in the art, preferably a vacuum deposition process, or a solution process such as a spin coating process.

[0059] The electron transport buffer layer 10 may also contain one or more selected from lithium fluoride (LiF), magnesium fluoride (MgF), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF), aluminum oxide (AlO), and calcium fluoride (CaF), and preferably contains lithium fluoride (LiF).

[0060] Specifically, the electron transport buffer layer 10 may have a structure in which a passivation buffer layer 3, a carbon-based electron transport layer 2, and a hole blocking buffer layer 1 are sequentially stacked. In this case, the passivation buffer layer 3 may be stacked on one side of the perovskite light absorbing layer, and the hole blocking buffer layer 1 may be stacked on one side of the electron transport layer.

[0061] The passivation buffer layer 3 is included in the perovskite solar cell of the present invention and is a layer that plays a role in passivation. It may contain one or more selected from lithium fluoride (LiF), magnesium fluoride (MgF2), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF3), aluminum oxide (Al2O3), and calcium fluoride (CaF2), and preferably contains lithium fluoride (LiF).

[0062] Furthermore, the passivation buffer layer 3 may have an average thickness of 0.5 to 5 nm, preferably 0.5 to 1.5 nm. If the average thickness is less than 0.5 nm, there may be a problem of energy level mismatch due to loss of passivation properties, and if it exceeds 5 nm, there may be a problem of loss of charge transfer ability due to insulating properties.

[0063] The carbon-based electron transport layer 2 may include a fullerene-based organic material. In this case, the fullerene-based organic material is C 60 , C 70 , PC60BM and PC70BM, and preferably C 60 may include:

[0064] Furthermore, the carbon-based electron transport layer 2 may have an average thickness of 3 to 30 nm, preferably an average thickness of 5 to 20 nm, and more preferably an average thickness of 11 to 15 nm. If the average thickness is less than 3 nm, the layer will not be formed uniformly on the rough surface of the perovskite light-absorbing layer, which may result in a problem of reduced charge transport ability. If the average thickness exceeds 30 nm, the layer will absorb light that should be absorbed by the perovskite light-absorbing layer, thereby interfering with the light-receiving properties of the perovskite light-absorbing layer and resulting in a problem of reduced solar cell performance.

[0065] The hole-blocking buffer layer 1 is included in the perovskite solar cell of the present invention and is a layer that functions as a hole blocker. It may contain one or more selected from lithium fluoride (LiF), magnesium fluoride (MgF), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF), aluminum oxide (AlO), and calcium fluoride (CaF), and preferably contains lithium fluoride (LiF).

[0066] The hole-blocking buffer layer 1 may have an average thickness of 0.5 to 5 nm, preferably 0.5 to 1.5 nm. If the average thickness is less than 0.5 nm, it may hinder the improvement of energy matching and may hinder the uniform growth of atomic layers in the initial nucleus growth stage during the formation of the electron transport layer, making it difficult to form a uniform ultra-thin film. If the average thickness exceeds 5 nm, it may cause a problem of reduced charge transport characteristics due to insulating properties.

[0067] The carbon-based electron transport layer 2 and the passivation buffer layer 3 may have a thickness ratio of 1:0.01 to 0.2, preferably 1:0.05 to 0.08.

[0068] The carbon-based electron transport layer 2 and the hole-blocking buffer layer 1 may have a thickness ratio of 1:0.01 to 0.2, preferably 1:0.05 to 0.08.

[0069] The electron transporting layer (ETL) is a layer that transports electrons formed in the perovskite light absorbing layer while blocking the movement of holes, and may contain one or more selected from tin oxide (SnOx), nickel oxide (NiOx), tin oxide (SnO2), titanium dioxide (TiO2), zinc oxide (ZnO), barium tin oxide (BaSnO3), niobium hydroxide (NbOH), and niobium pentoxide (Nb2O5).

[0070] Examples of methods for forming the electron transport layer include coating methods, ALD vapor deposition methods, and / or vacuum vapor deposition methods. Examples of coating methods include gravure coating methods, bar coating methods, printing methods, spraying methods, spin coating methods, dipping methods, and die coating methods.

[0071] The thickness of the electron transport layer is not particularly limited, but may preferably have an average thickness of 3 to 30 nm, more preferably 3 to 15 nm, and even more preferably 10 to 13 nm. In this case, the thickness ratio of the electron transport layer to the electron transport buffer layer may be 1:1.1 to 2.4, preferably 1:1.36 to 2.04.

[0072] The transparent electrode may be formed on the electron transport layer through a deposition process, which may be a common deposition process used in the art, and preferably may be a sputtering process.

[0073] The transparent electrode may be a transparent thin film formed by vapor deposition of ITO (Indium Tin Oxide), FTO (Fluorine doped Tin Oxide), ATO (Sb2O3 doped Tin Oxide), GTO (Gallium doped Tin Oxide), ZTO (tin doped zinc oxide), ZTO:Ga (gallium doped ZTO), IGZO (Indium gallium zinc oxide), IZO (Indium doped zinc oxide), or AZO (Aluminum doped zinc oxide).

[0074] Furthermore, the thickness of the transparent electrode is not particularly limited, but may preferably be 50 to 200 nm, more preferably 60 to 140 nm.

[0075] The metal electrode can be formed by patterning a metal material on the transparent electrode. Specifically, the patterning process is roughly composed of deposition, lithography, and etching. The metal material is deposited in the form of a thin film on one side of the substrate, and a pattern is printed by lithography, and then unnecessary portions are removed to form the metal electrode on the transparent electrode. The patterning process can also be performed by a screen printing method using a metal paste containing the metal material.

[0076] In this case, the metal substance may include one or more selected from Pt, Au, Ni, Cu, Ag, In, Ru, Pd, Rh, Ir, Os, C, and conductive polymers.

[0077] Furthermore, there is no particular limitation on the thickness of the metal electrode, but it may preferably have a thickness of 50 nm to 2.5 μm.

[0078] The method for manufacturing a perovskite solar cell of the present invention may include a first step of forming a perovskite light-absorbing layer on top of a hole-transporting layer, a second step of forming an electron-transporting buffer layer on top of the perovskite light-absorbing layer through a vapor deposition process or a solution process, and a third step of sequentially forming an electron-transporting layer, a transparent electrode, and a metal electrode on top of the electron-transporting buffer layer.

[0079] In this case, the electron transport buffer layer may have a structure in which a passivation buffer layer 3, a carbon-based electron transport layer 2, and a hole blocking buffer layer 1 are sequentially stacked.

[0080] Specifically, the second step of the method for manufacturing a perovskite solar cell of the present invention may include: step 2-1 of forming a passivation buffer layer on the perovskite light absorbing layer through a vapor deposition process or a solution process; step 2-2 of forming a carbon-based electron transport layer on the passivation buffer layer through a vapor deposition process or a solution process; and step 2-3 of forming a hole-blocking buffer layer on the carbon-based electron transport layer through a vapor deposition process or a solution process.

[0081] More specifically, the passivation buffer layer can be formed through a vacuum deposition process, the carbon-based electron transport layer can be formed through a vacuum deposition process, and the hole blocking buffer layer can be formed through a vacuum deposition process.

[0082] The present invention will be described in more detail below with reference to examples. However, it should be understood that the following examples do not limit the scope of the present invention, but are merely intended to aid in the understanding of the present invention.

[0083] Example 1: Fabrication of tandem silicon / perovskite heterojunction solar cells (1) Silicon solar cells (thickness: 180 μm) doped with n- or p-type impurities were prepared, and the SiOx oxide film was removed by hydrofluoric acid treatment. After that, the remaining hydrofluoric acid was removed using ultrapure water. A transparent conductive layer (ITO) with a thickness of 20 nm was formed on the silicon solar cells from which the oxide film had been removed through a sputtering process.

[0084] (2) Next, a hole transport layer (NiOx) with a thickness of 20 nm was formed on the transparent conductive layer by sputtering vacuum deposition.

[0085] (3) Next, a yellow light absorbing layer solution was formed by spin coating on top of the hole transport layer, which was dissolved in dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). This was then heat-treated at 125°C for 20 minutes to form a 300 nm thick perovskite light absorbing layer (CSFAPbI x Br 3-X (0≦x≦3)) was formed.

[0086] (4) Next, lithium fluoride (LiF) was deposited on top of the perovskite light absorbing layer through a vacuum deposition process to form a passivation buffer layer with an average thickness of 1 nm.

[0087] (5) Next, C is deposited on top of the passivation buffer layer through a vacuum deposition process. 60 Fullerene (C 60 fullerene) was evaporated to form a carbon-based electron transport layer with an average thickness of 15 nm.

[0088] (6) Next, lithium fluoride (LiF) was deposited on top of the carbon-based electron transport layer through a vacuum deposition process to form a hole-blocking buffer layer with an average thickness of 1 nm.

[0089] (7) Next, an electron transport layer (SnO2) with an average thickness of 10 nm was formed on the hole blocking buffer layer through an ALD (atomic layer deposition) deposition process.

[0090] (8) Next, a transparent electrode (ITO) with a thickness of 75 nm was formed on the electron transport layer through a sputtering process.

[0091] (9) Finally, 1×10 silver (Ag) was applied to the top of the transparent electrode. -7 A tandem silicon / perovskite heterojunction solar cell was fabricated by depositing a metal electrode to a thickness of 100 nm at a pressure of 100 torr. This resulted in the fabrication of a tandem silicon / perovskite heterojunction solar cell in which a silicon solar cell, a transparent conductive layer, a hole transport layer, a perovskite light absorbing layer, a passivation buffer layer, a carbon-based electron transport layer, a hole blocking buffer layer, an electron transport layer, a transparent electrode, and a metal electrode were sequentially stacked.

[0092] Example 2: Fabrication of tandem silicon / perovskite heterojunction solar cells (1) Silicon solar cells (thickness: 180 μm) doped with n- or p-type impurities were prepared, and the SiOx oxide film was removed by hydrofluoric acid treatment. After that, the remaining hydrofluoric acid was removed using ultrapure water. A transparent conductive layer (ITO) with a thickness of 20 nm was formed on the silicon solar cells from which the oxide film had been removed through a sputtering process.

[0093] (2) Next, a hole transport layer (NiOx) with a thickness of 20 nm was formed on the transparent conductive layer by sputtering vacuum deposition.

[0094] (3) Next, a yellow light absorbing layer solution was formed by spin coating on top of the hole transport layer, which was dissolved in dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). This was then heat-treated at 125°C for 20 minutes to form a 300 nm thick perovskite light absorbing layer (CSFAPbI x Br 3-X (0≦x≦3)) was formed.

[0095] (4) Next, lithium fluoride (LiF) was deposited on top of the perovskite light absorbing layer through a vacuum deposition process to form a passivation buffer layer with an average thickness of 1 nm.

[0096] (5) Next, C is deposited on top of the passivation buffer layer through a vacuum deposition process. 60 Fullerene (C 60 fullerene) was evaporated to form a carbon-based electron transport layer with an average thickness of 15 nm.

[0097] (6) Next, an electron transport layer (SnO2) with an average thickness of 10 nm was formed on top of the carbon-based electron transport layer through an atomic layer deposition (ALD) deposition process.

[0098] (7) Next, a transparent electrode (ITO) with a thickness of 75 nm was formed on the electron transport layer through a sputtering process.

[0099] (8) Finally, 1×10 silver (Ag) was applied to the top of the transparent electrode. -7 By depositing a metal electrode to a thickness of 100 nm at a pressure of 100 torr, a tandem silicon / perovskite heterojunction solar cell was fabricated in which a silicon solar cell, a transparent conductive layer, a hole transport layer, a perovskite light absorption layer, a passivation buffer layer, a carbon-based electron transport layer, an electron transport layer, a transparent electrode, and a metal electrode were sequentially stacked.

[0100] Example 3: Fabrication of tandem silicon / perovskite heterojunction solar cells (1) Silicon solar cells (thickness: 180 μm) doped with n- or p-type impurities were prepared, and the SiOx oxide film was removed by hydrofluoric acid treatment. After that, the remaining hydrofluoric acid was removed using ultrapure water. A transparent conductive layer (ITO) with a thickness of 20 nm was formed on the silicon solar cells from which the oxide film had been removed through a sputtering process.

[0101] (2) Next, a hole transport layer (NiOx) with a thickness of 20 nm was formed on the transparent conductive layer by sputtering vacuum deposition.

[0102] (3) Next, a yellow light absorbing layer solution was formed on the top of the hole transport layer by spin coating using dimethylformamide (DMF) and dimethyl sulfoxide (DMSO). This was then heat-treated at 100°C for 20 minutes to form a 300 nm thick perovskite light absorbing layer (CSFAPbI x Br 3-X (0≦x≦3)) was formed.

[0103] (4) Next, PCBM was coated on top of the perovskite light-absorbing layer through a solution process to form a passivation buffer layer with an average thickness of 10 nm.

[0104] (5) Next, C is deposited on top of the passivation buffer layer through a vacuum deposition process. 60 Fullerene (C 60 fullerene) was evaporated to form a carbon-based electron transport layer with an average thickness of 15 nm.

[0105] (6) Next, an electron transport layer (SnO2) with an average thickness of 10 nm was formed on the hole blocking buffer layer through an ALD (atomic layer deposition) deposition process.

[0106] (7) Next, a transparent electrode (ITO) with a thickness of 75 nm was formed on the electron transport layer through a sputtering process.

[0107] (8) Finally, 1×10 silver (Ag) was applied to the top of the transparent electrode. -7 A tandem silicon / perovskite heterojunction solar cell was fabricated by depositing a metal electrode to a thickness of 100 nm at a pressure of 100 torr. This resulted in the fabrication of a tandem silicon / perovskite heterojunction solar cell in which a silicon solar cell, a transparent conductive layer, a hole transport layer, a perovskite light absorbing layer, a passivation buffer layer, a carbon-based electron transport layer, a hole blocking buffer layer, an electron transport layer, a transparent electrode, and a metal electrode were sequentially stacked.

[0108] Experimental example 1: Measuring the performance of solar cells FIG. 2 is a graph showing the current density as a function of applied voltage for each of the tandem silicon / perovskite heterojunction solar cells manufactured in Examples 1 to 3, measured by a JV measurement method using an LED lamp.

[0109] As can be seen from the left graph in Figure 2, the tandem silicon / perovskite heterojunction solar cell fabricated in Example 1, which has a structure in which a passivation buffer layer, a carbon-based electron transport layer, a hole-blocking buffer layer, and an electron transport layer are sequentially stacked, physically blocks holes from migrating to the electron transport layer, thereby enhancing hole-blocking properties, and selectively allows electrons to migrate, minimizing charge recombination at the interface, thereby suppressing shunting and improving the fill factor. Furthermore, the ultra-thin hole-blocking buffer layer enables the formation of a dense thin film, inhibiting molecules that cause charge loss and facilitating charge collection, resulting in an increased short-circuit current density.

[0110] Furthermore, as can be seen from the right graph of Figure 2, compared to the tandem silicon / perovskite heterojunction solar cell fabricated in Example 3 using PCBM as the passivation buffer layer, the tandem silicon / perovskite heterojunction solar cell fabricated in Example 1 using lithium fluoride (LiF) as the passivation buffer layer improved energy matching, resulting in an increased open-circuit voltage, and also improved short-circuit current density by inducing only the passivation effect.

[0111] Furthermore, for each of the tandem silicon / perovskite heterojunction solar cells produced in Examples 1 to 3, efficiency was measured using a sunlight simulator and a JV Keithley device and an initial JV curve, and the results are shown in Table 1 below.

[0112] [Table 1]

[0113] As can be seen from Table 1, the tandem silicon / perovskite heterojunction solar cell fabricated in Example 1 was found to have the best open circuit voltage, short circuit current density, fill factor, and power conversion efficiency.

[0114] Experimental Example 2: Analysis of the surface chemical properties of the electron transport layer The surface chemical properties of the electron transport layer of each of the tandem silicon / perovskite heterojunction solar cells fabricated in Examples 1 and 2 were analyzed using photoelectron spectroscopy (XPS), and are shown in Table 2 below.

[0115] [Table 2]

[0116] As can be seen from Table 2, the tandem silicon / perovskite heterojunction solar cell fabricated in Example 1 had a reduced work function (WF) and an increased valence band maximum (VBM), which was advantageous for charge transport, compared to the tandem silicon / perovskite heterojunction solar cell fabricated in Example 2. In addition, the tandem silicon / perovskite heterojunction solar cell fabricated in Example 1 had an increased O / Sn ratio and a decreased N / Sn ratio compared to the tandem silicon / perovskite heterojunction solar cell fabricated in Example 2, which confirmed that the electron transport layer had fewer surface defects and a stoichiometrically stable film was formed.

[0117] In conclusion, it was confirmed that the tandem silicon / perovskite heterojunction solar cell fabricated in Example 1 can increase the open circuit voltage due to the matching of energy levels, and increase the short circuit current density and fill factor due to the strengthening of surface properties.

[0118] Although specific embodiments have been illustrated and described above, the present invention is not limited to the above-described embodiments, and a person skilled in the art can make various modifications without departing from the scope of the technical idea of ​​the invention described in the following claims.

Claims

1. The present invention relates to a layered structure in which a hole transport layer, a perovskite light absorbing layer, an electron transport layer, a transparent electrode, and a metal electrode are sequentially stacked, an electron transport buffer layer is formed between the perovskite light absorbing layer and the electron transport layer; The electron transfer buffer layer is made of lithium fluoride (LiF), magnesium fluoride (MgF ２ ), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF ３ ), aluminum oxide (Al ２ O ３ ) and calcium fluoride (CaF ２ ) A perovskite solar cell comprising one or more selected from the group consisting of:

2. The electron transport buffer layer has a structure in which a passivation buffer layer, a carbon-based electron transport layer, and a hole blocking buffer layer are sequentially stacked, 2. The perovskite solar cell according to claim 1, wherein the passivation buffer layer is stacked on one surface of the perovskite light absorbing layer, and the hole blocking buffer layer is stacked on one surface of the electron transport layer.

3. The passivation buffer layer and the hole blocking buffer layer are made of lithium fluoride (LiF), magnesium fluoride (MgF ２ ), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF ３ ), aluminum oxide (Al ２ O ３ ) and calcium fluoride (CaF ２ ) and one or more selected from The perovskite solar cell according to claim 2 , wherein the carbon-based electron transport layer comprises a fullerene-based organic material.

4. The fullerene-based organic material is C ６０ , C ７０ 4. The perovskite solar cell according to claim 3, characterized in that it contains one or more selected from the group consisting of PC60BM, PC60BM, and PC70BM.

5. the carbon-based electron transport layer and the passivation buffer layer have a thickness ratio of 1:0.01 to 0.2; The perovskite solar cell of claim 2, wherein the carbon-based electron transport layer and the hole-blocking buffer layer have a thickness ratio of 1:0.01 to 0.

2.

6. each of the passivation buffer layer and the hole-blocking buffer layer has an average thickness of 0.5 to 5 nm; The perovskite solar cell of claim 2, wherein the carbon-based electron transport layer has an average thickness of 3 to 30 nm.

7. The perovskite solar cell according to claim 1, wherein the electron transport layer and the electron transport buffer layer have a thickness ratio of 1:1.1 to 2.

4.

8. The perovskite solar cell according to claim 1, wherein the electron transport layer has an average thickness of 3 to 30 nm.

9. The perovskite solar cell according to any one of claims 1 to 8, wherein the perovskite solar cell is a pin structure perovskite solar cell, an nip inverted structure perovskite solar cell, a tandem perovskite solar cell, or a tandem silicon / perovskite heterojunction solar cell.

10. A first step of forming a perovskite light absorbing layer on top of a hole transport layer; A second step of forming an electron transfer buffer layer on the perovskite light absorbing layer through a deposition process or a solution process; and a third step of sequentially forming an electron transport layer, a transparent electrode, and a metal electrode on the electron transport buffer layer; The electron transfer buffer layer is made of lithium fluoride (LiF), magnesium fluoride (MgF ２ ), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF ３ ), aluminum oxide (Al ２ O ３ ) and calcium fluoride (CaF ２ ) ) ) ).

11. The second stage comprises: Step 2-1: forming a passivation buffer layer on the perovskite light absorbing layer through a deposition process or a solution process; Step 2-2: forming a carbon-based electron transport layer on the passivation buffer layer through a deposition process or a solution process; and Steps 2-3: forming a hole-blocking buffer layer on the carbon-based electron transport layer through a deposition process or a solution process; 11. The method for producing a perovskite solar cell according to claim 10, comprising:

12. A heterojunction solar cell in which a solar cell, a transparent conductive layer, a hole transport layer, a perovskite light absorbing layer, an electron transport buffer layer, an electron transport layer, a transparent electrode, and a metal electrode are sequentially stacked, The electron transfer buffer layer is made of lithium fluoride (LiF), magnesium fluoride (MgF ２ ), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF ３ ), aluminum oxide (Al ２ O ３ ) and calcium fluoride (CaF ２ ) A tandem silicon / perovskite heterojunction solar cell comprising one or more selected from the group consisting of:

13. The electron transport buffer layer has a structure in which a passivation buffer layer, a carbon-based electron transport layer, and a hole blocking buffer layer are sequentially stacked, 13. The tandem silicon / perovskite heterojunction solar cell of claim 12, wherein the passivation buffer layer is stacked on one side of the perovskite light absorbing layer, and the hole blocking buffer layer is stacked on one side of the electron transport layer.

14. The passivation buffer layer and the hole blocking buffer layer are made of lithium fluoride (LiF), magnesium fluoride (MgF ２ ), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF ３ ), aluminum oxide (Al ２ O ３ ) and calcium fluoride (CaF ２ ) and one or more selected from The tandem silicon / perovskite heterojunction solar cell of claim 13, wherein the carbon-based electron transport layer comprises a fullerene-based organic material.

15. The solar cells include polycrystalline silicon solar cells, crystalline silicon solar cells, perovskite solar cells, gallium arsenide (GaAs) solar cells, cadmium telluride (CdTe) solar cells, CIGS (CuInGaSe) solar cells, CZTS (Cu ２ ZnSnS ４ 13. The tandem silicon / perovskite heterojunction solar cell according to claim 12, which is a silicon-based solar cell, an organic solar cell, a dye-sensitized solar cell, or a III-V compound solar cell.

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