Laminated silicon / perovskite heterojunction solar cell and manufacturing method thereof

Abstract

The present invention relates to a heterojunction solar cell formed of a solar cell, a transparent conductive layer, a hole transport layer, a perovskite light absorption layer, an electron transport layer, a transparent electrode, and a metal electrode which are sequentially stacked, and a method for manufacturing the same, wherein the perovskite light absorption layer comprises a perovskite material represented by Chemical Formula 1 and a benzyl hydrazine oxalate, charge collection capability can be improved by reducing charge recombination in the perovskite light absorption layer, and deterioration of the solar cell can be reduced, so that improved performance can be exhibited in terms of stability. [Chemical Formula 1] FACsPbX3 In Chemical Formula 1, X is a monovalent anion.

Description

Technical Field

[0001] This invention relates to a tandem silicon / perovskite heterojunction solar cell in which benzyl hydrazine oxalate is introduced as an additive into a perovskite light-absorbing layer, and a method for manufacturing the same. Background Technology

[0002] To address the global environmental problems caused by the depletion and use of fossil fuels, research is actively underway on renewable and clean alternative energy sources such as solar, wind, and hydropower.

[0003] Among these, interest in solar cells, which directly convert sunlight into electricity, is increasing significantly. Here, a solar cell refers to a cell that generates current and voltage by utilizing the photovoltaic effect, which produces electrons and holes by absorbing light energy from sunlight.

[0004] Currently, NP diode-type silicon (Si) single-crystal solar cells with light conversion efficiencies exceeding 20% ​​can be manufactured, and they have been practically used in solar power generation. There are also solar cells using compound semiconductors such as gallium arsenide (GaAs) with even higher conversion efficiencies. However, these inorganic semiconductor-based solar cells require highly purified materials to achieve high efficiency. Therefore, the refining of raw materials consumes a significant amount of energy, and the manufacturing of single crystals or thin films using these raw materials requires expensive processing equipment. This limits efforts to reduce the manufacturing cost of solar cells and has become an obstacle to large-scale application.

[0005] Therefore, in order to manufacture solar cells at low cost, it is necessary to significantly reduce the cost of materials or manufacturing processes used as the core components of solar cells. Thus, research is underway 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 using (NH3CH3)PbX3 (X = I, Br, Cl) (a halide compound with a perovskite structure) as a photosensitizer have been developed, and research towards commercialization is underway. The general structural formula of the perovskite structure is ABX3, where the anion is located at the X position, the large cation is located at the A position, and the small cation is located at the B position.

[0007] Perovskite solar cells (organometal halide compounds with the molecular formula (CH3NH3)PbX3) were first used as photosensitive materials in solar cells in 2009. Since then, efficiency has rapidly improved since the development of solid-state perovskite solar cells with the current structure in 2012. Conventional perovskite solar cells use metal oxides as electron transport layers and also as hole transport layers (HTLs), but organic or polymeric materials such as spiro-OMETADs can also be used. That is, a porous film or thin film of metal oxide is prepared on a transparent electrode such as FTO / ITO as an electron transport layer / hole transport layer, and then a perovskite material is coated on top. Subsequently, a porous film or thin film of metal oxide is prepared as a hole transport layer / electron transport layer, and then an electrode layer such as gold (Au) or silver (Ag) is deposited.

[0008] Perovskite solar cells (organometallic halide compounds with the molecular formula (CH3NH3)PbX3) use halide ions such as I, Br, and Cl in their molecular formulas, where X is a halide ion such as I, Br, or Cl. In this case, excess halogens that do not participate in the formation of the perovskite crystal phase exist as ionic defects and are not fixed in the perovskite crystal. Instead, they can escape from the crystal as halides combined with hydrogen or light cations, thus exhibiting high diffusivity. Therefore, after the fabrication of Si / perovskite tandem solar cells, halide ions can easily diffuse unrestricted into the surrounding layers due to heating, light irradiation, or electrical externalities that are crucial in subsequent module processing.

[0009] Meanwhile, the upper perovskite film used in tandem solar cells is configured with a bandgap of 1.60 eV to 1.70 eV to match the current of the lower silicon solar cell in a double-ended structure, and the bandgap of the perovskite can be controlled according to the ratio of ABX3 constituting the perovskite. In the constituent materials of the perovskite film used to configure tandem solar cells, the materials corresponding to the A sites include MA. + (Methylammonium cation), FA + (formamidinium cation), Cs + (cesium cations), etc., and composed of combinations of these.

[0010] Recently, due to MA + The thermal stability issue is being addressed by developing a system that does not contain MA. + The perovskite layer. The material corresponding to the B site is Pb. 2+ (Lead cation), the material corresponding to the X site is Cl. - (Chloride anion), Br - (bromoanion), I - (Iodine anions), etc., the components of perovskite formed by combinations of these are often used as the upper layer of tandem solar cells.

[0011] The main methods for manufacturing perovskite thin films are coating (=solution) and deposition. Deposition requires vacuum equipment, so coating (=solution) is the main method as it is simpler.

[0012] To form conventional perovskite thin films, the perovskite material is placed in a solvent to form a precursor state (which is a solution state). In this case, the main solvents used are DMF, 2-ME, etc., with NMP, DMPU, HMPA, THTO, etc., used as additive solvents. When the solution is stored here, I... - Ions are easily reduced to I2 / I3 - This leads to a long-term performance degradation in silicon / perovskite tandem solar cells.

[0013] Meanwhile, in the coating (=solution) process, the crystallization into a thin film via heat treatment in the solution state is crucial for the formation of the perovskite layer. However, perfect crystallization cannot be achieved without component loss during this process, and defects inevitably arise during heat treatment. Furthermore, rapid crystallization occurs without forming large grain sizes, thus generating numerous grain boundaries. These grain boundaries can act as recombination centers for charge movement, which becomes an obstacle to achieving good performance.

[0014] In particular, when it diffuses into the metal electrodes, such as gold (Au) or silver (Ag), in Si / perovskite tandem solar cells, it not only corrodes the interface between the transparent electrode and the metal electrode, increasing the interfacial contact resistance, but also causes metal ions to leak into the solar cell due to the corrosion of the metal electrode, which reduces the performance of the solar cell. Summary of the Invention

[0015] Technical issues

[0016] The present invention aims to overcome the above-mentioned problems and relates to providing a tandem silicon / perovskite heterojunction solar cell and a method for manufacturing the same: by introducing benzylhydrazine oxalate as an additive into the perovskite light-absorbing layer to reduce charge recombination in the perovskite light-absorbing layer, the charge collection capability can be improved, and the degradation of the solar cell can also be reduced, thereby exhibiting improved performance in terms of stability.

[0017] Technical solution

[0018] To address the aforementioned issues, the tandem silicon / perovskite heterojunction solar cell of the present invention comprises a solar cell, a transparent conductive layer, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a transparent electrode, and a metal electrode stacked sequentially.

[0019] In a preferred embodiment of the present invention, the perovskite light-absorbing layer may comprise a perovskite material represented by the following chemical formula 1 and benzylhydrazine oxalate:

[0020] [Chemical Formula 1]

[0021] FACsPbX3

[0022] In the above chemical formula 1, X is a monovalent anion.

[0023] In a preferred embodiment of the present invention, the perovskite light-absorbing layer may comprise a perovskite material represented by the above chemical formula 1 and benzylhydrazine oxalate in a weight ratio of 1:0.0001 to 0.002.

[0024] In a preferred embodiment of the present invention, the average thickness of the perovskite light-absorbing layer can be from 450 nm to 700 nm.

[0025] In a preferred embodiment of the present invention, the tandem silicon / perovskite heterojunction solar cell may further include a first interface layer between the hole transport layer and the perovskite light absorption layer.

[0026] In a preferred embodiment of the present invention, the first interface layer may comprise a p-type organic molecular SAM interface coating agent.

[0027] In a preferred embodiment of the present invention, the thickness of the first interface layer can be from 0.5 nm to 10 nm.

[0028] In a preferred embodiment of the present invention, the tandem silicon / perovskite heterojunction solar cell may further include a second interface layer between the perovskite light-absorbing layer and the electron transport layer.

[0029] In a preferred embodiment of the present invention, the second interface layer may comprise one or more of lithium fluoride (LiF), magnesium fluoride (MgF2), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF3), and calcium fluoride (CaF2).

[0030] In a preferred embodiment of the present invention, the thickness of the second interface layer can be from 0.5 nm to 10 nm.

[0031] In a preferred embodiment of the present invention, the tandem silicon / perovskite heterojunction solar cell may further include an intermediate layer between the second interface layer and the electron transport layer.

[0032] In a preferred embodiment of the present invention, the intermediate layer may comprise fullerene-based organic materials.

[0033] Meanwhile, the method for manufacturing a tandem silicon / perovskite heterojunction solar cell according to the present invention may include step 1: sequentially stacking a solar cell, a transparent conductive layer, a hole transport layer and a first interface layer; step 2: forming a perovskite light-absorbing layer on the first interface layer by coating; and step 3: sequentially forming a second interface layer, an intermediate layer, an electron transport layer, a transparent electrode and a metal electrode on the perovskite light-absorbing layer.

[0034] In a preferred embodiment of the present invention, the perovskite light-absorbing layer may comprise a perovskite material represented by the following chemical formula 1 and benzylhydrazine oxalate:

[0035] [Chemical Formula 1]

[0036] FACsPbX3

[0037] In the above chemical formula 1, X is a monovalent anion.

[0038] In a preferred embodiment of the present invention, the coating method may be gravure coating, bar coating, printing, spraying, spin coating, scraping coating, dip coating, or mold coating.

[0039] In a preferred embodiment of the present invention, in the perovskite light-absorbing layer, the perovskite material represented by the above chemical formula 1 and benzylhydrazine oxalate can be mixed in a weight ratio of 1:0.0001 to 0.002.

[0040] In a preferred embodiment of the present invention, the first interface layer may be formed by including the following steps: step (1): heating the hole transport layer; step (2): coating the heated hole transport layer with a P-type organic molecular SAM interface coating agent; and step (3): drying the coated P-type organic molecular SAM interface coating agent to form the first interface layer.

[0041] Beneficial effects

[0042] The tandem silicon / perovskite heterojunction solar cell and its manufacturing method of the present invention utilize the introduction of benzylhydrazine oxalate as an additive during the formation of the perovskite light-absorbing layer to enhance the I2 / I3 ratio. - Restore to I - This can reduce the formation of traps.

[0043] Furthermore, the tandem silicon / perovskite heterojunction solar cell and its manufacturing method of the present invention can delay the growth of crystal nuclei during the crystal growth of the perovskite light-absorbing layer, thereby allowing for better growth into individual grains.

[0044] Furthermore, the tandem silicon / perovskite heterojunction solar cell and its manufacturing method of the present invention utilize (C2O4) 2-Replacing halide defects can more effectively mitigate the resulting defects. Detailed Implementation

[0045] The invention will be described in more detail below.

[0046] To form conventional perovskite thin films, the perovskite material is placed in a solvent to form a precursor state (which is a solution state). In this case, the main solvents used are DMF, 2-ME, etc., with NMP, DMPU, HMPA, THTO, etc., present as additive solvents. When the solution is stored here, I... - Ions are easily reduced to I2 / I3 - This leads to a long-term performance degradation in silicon / perovskite tandem solar cells.

[0047] Meanwhile, in the coating (=solution) process, the crystallization into a thin film via heat treatment in the solution state is crucial for the formation of the perovskite layer. However, perfect crystallization cannot be achieved without component loss during this process, and defects inevitably arise during heat treatment. Furthermore, rapid crystallization occurs without forming large grain sizes, thus generating numerous grain boundaries. These grain boundaries can act as recombination centers for charge movement, which becomes an obstacle to achieving good performance.

[0048] In particular, when it diffuses into the metal electrodes, such as gold (Au) or silver (Ag), in Si / perovskite tandem solar cells, it not only corrodes the interface between the transparent electrode and the metal electrode, increasing the interfacial contact resistance, but also causes metal ions to leak into the solar cell due to the corrosion of the metal electrode, which reduces the performance of the solar cell.

[0049] Therefore, the present invention relates to a tandem silicon / perovskite heterojunction solar cell: by introducing benzylhydrazine oxalate as an additive into the perovskite light-absorbing layer to reduce charge recombination in the perovskite light-absorbing layer, the charge collection capability can be improved, and the degradation of the solar cell can also be reduced, thereby exhibiting improved performance in terms of stability.

[0050] The stacked silicon / perovskite heterojunction solar cell of the present invention can be a heterojunction solar cell having a structure in which a solar cell, a transparent conductive layer, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, a transparent electrode, and a metal electrode are sequentially stacked.

[0051] Furthermore, the tandem silicon / perovskite heterojunction solar cell of the present invention may further include a first interface layer between the hole transport layer and the perovskite light-absorbing layer. In this case, the tandem silicon / perovskite heterojunction solar cell of the present invention can be a heterojunction solar cell having a structure in which a solar cell, a transparent conductive layer, a hole transport layer, a first interface layer, a perovskite light-absorbing layer, an electron transport layer, a transparent electrode, and a metal electrode are sequentially stacked.

[0052] Furthermore, the tandem silicon / perovskite heterojunction solar cell of the present invention may also include a second interface layer between the perovskite light-absorbing layer and the electron transport layer. In this case, the tandem silicon / perovskite heterojunction solar cell of the present invention can be a heterojunction solar cell having a structure in which a solar cell, a transparent conductive layer, a hole transport layer, a perovskite light-absorbing layer, a second interface layer, an electron transport layer, a transparent electrode, and a metal electrode are sequentially stacked.

[0053] Meanwhile, the stacked silicon / perovskite heterojunction solar cell of the present invention can be a heterojunction solar cell having a structure in which a solar cell, a transparent conductive layer, a hole transport layer, a first interface layer, a perovskite light absorption layer, a second interface layer, an electron transport layer, a transparent electrode, and a metal electrode are sequentially stacked.

[0054] Furthermore, the tandem silicon / perovskite heterojunction solar cell of the present invention may also include an intermediate layer between the second interface layer and the electron transport layer. In this case, the tandem silicon / perovskite heterojunction solar cell of the present invention can be a heterojunction solar cell having a structure in which a solar cell, a transparent conductive layer, a hole transport layer, a first interface layer, a perovskite light-absorbing layer, a second interface layer, an intermediate layer, an electron transport layer, a transparent electrode, and a metal electrode are sequentially stacked.

[0055] Solar cells can be 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 (Cu2ZnSnS4) solar cells, organic solar cells, dye-sensitized solar cells, or III-V compound solar cells.

[0056] Furthermore, there is no separate limitation on the thickness of the solar cell, but its thickness can preferably be from 140 μm to 250 μm, more preferably from 160 μm to 200 μm.

[0057] The transparent conductive layer is a layer that induces the recombination of electrons and holes generated in the solar cell and the perovskite light-absorbing layer described later, and a transparent thin film 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) can be deposited on it.

[0058] Furthermore, as an example of forming a transparent conductive layer, when using a silicon solar cell doped with n-type or p-type impurities as the solar cell, the silicon solar cell doped with n-type or p-type impurities can be treated with hydrofluoric acid to remove the SiOx oxide film. Then, the remaining hydrofluoric acid is removed using ultrapure water. A transparent conductive layer can then be formed on the silicon solar cell with the oxide film removed by sputtering.

[0059] Furthermore, there is no particular limitation on the thickness of the transparent conductive layer, but the thickness can preferably be from 5 nm to 50 nm, more preferably from 15 nm to 25 nm.

[0060] Hole transport layer (HTL) is a layer that transports holes formed in a perovskite light-absorbing layer as described below while blocking the movement of electrons, and may contain inorganic and / or organic hole transport materials.

[0061] In this case, the inorganic hole transport material may include one or more of nickel oxide (NiOx), CuSCN, CuCrO2, CuI, MoO and V2O5.

[0062] In addition, organic hole transport materials may include one or more of the following: carbazole derivatives, polyaryl alkane derivatives, phenylenediamine derivatives, aryl amine derivatives, amino-substituted chalcone derivatives, styrene-anthracene derivatives, fluorene derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrene-amine compounds, aromatic dimethylene compounds, porphyrin compounds, phthalocyanine compounds, polythiophene derivatives, polypyrrole derivatives, poly(p-phenyleneacetylene) derivatives, pentacene, coumarin 6 (coumarin 6,3-(2-benzothiazolyl)-7-(diethylamino)coumarin), ZnPC (zinc phthalocyanine), CuPC (copper phthalocyanine), and TiOPC (titanium oxide phthalocyanine). Spiro-MeOTAD (2,2',7,7'-tetratetra(N,N-p-dimethoxyphenylamino)-9,9'-spirodifluorene), F16CuPC (copper(II)1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecylfluoro-29H,31H-phthalocyanine), SubPc (boron phthalocyanine chloride), N3 (cis-di(cyanothio)-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)-ruthenium(II), P3HT (poly[3-hexylthiophene]), MDMO-PPV (poly[2-methoxy-5-(3',7'-dimethyloctyloxy)]-1,4-phenylacetylene), MEH- PPV (poly[2-methoxy-5-(2''-ethylhexyloxy)-p-phenylacetylene]), P3OT (poly(3-octylthiophene)), POT (poly(octylthiophene)), P3DT (poly(3-decylthiophene)), P3DDT (poly(3-dodecylthiophene)), PPV (poly(p-phenylacetylene)), TFB (poly(9,9'-dioctylfluorene-copolymer-N-(4-butylphenyl)diphenylamine), polyaniline, spiro-MeOTAD ([2,22',7,77'-tetra(N,N-di-p-methoxyaniline)-9,9,9'-spirodifluoro]), 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)dithiophene[3,2-b:2',3'-d]silaxenolide)-2,6-diyl-alternating-(2,1,3-benzothiadiazole)-4,7-diyl]), PBDTTPD (poly((4,8-diethylhexyloxy)), PFDTBT (poly[2,7-(9-(2-ethylhexyl)-9-hexyl-fluorene)-alternating-5,5-(4',7,-di-2-thienyl-2',1',3'-benzothiadiazole)]), PFO-DBT (poly[2,7-).9,9-(dioctyl-fluorene)-alternating-5,5-(4',7'-bis-2-thienyl-2',1',3'-benzothiadiazole)]), PSiFDTBT (poly[(2,7-dioctylsilylfluorene)-2,7-diyl-alternating-(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] [Base]), PFB (poly(9,9'-dioctylfluorene-copolymer-bis(N,N'-(4-butylphenyl))bis(N,N'-phenyl-1,4-phenylene)diamine), F8BT (poly(9,9'-dioctylfluorene-copolymer-benzothiadiazole), PEDOT (poly(3,4-ethylenedioxythiophene)), PEDOT:PSS poly(3,4-ethylenedioxythiophene) poly(styrene sulfonate), PTAA (poly(triarylamine)), 2-PACz, MeO-2PACz, Br-2PACz and Me-4PACz.

[0063] In addition, methods for forming hole transport layers include coating and vacuum deposition. Coating methods can include gravure coating, bar coating, printing, spraying, spin coating, blade coating, dip coating, and mold coating.

[0064] Furthermore, there is no particular limitation on the thickness of the hole transport layer, but the thickness can preferably be from 5 nm to 40 nm, more preferably from 10 nm to 30 nm.

[0065] The first interface layer plays a role in the efficient transport of holes by controlling the work function of the hole transport layer, and may contain a p-type organic molecular SAM interface coating agent. The p-type organic molecular SAM interface coating agent may contain PACz-based compounds and solvents.

[0066] The PACz series of compounds may include one or more of the following: 2-PACz ([2-(9H-carbazole-9-yl)ethyl]phosphonic acid), MeO-2PACz, Br-2PACz, Me-4PACz, MeO-4PACz, 6-PACz, and Me-6PACz. Furthermore, P-type organic molecular SAM interface coating agents may contain PACz series compounds at concentrations ranging from 0.30 mg / mL to 10.00 mg / mL.

[0067] Solvents may include one or more selected from methanol, ethanol, 1-propanol and 1-butanol.

[0068] Furthermore, the thickness of the first interface layer can be from 0.5 nm to 10 nm, preferably from 2 nm to 8 nm.

[0069] Furthermore, the surface roughness RMS (root mean square) of the first interface layer can be from 4.50 nm to 80.00 nm, preferably from 5.00 nm to 50.00 nm.

[0070] Furthermore, examples of methods for forming the first interface layer include coating and vacuum deposition; examples of coating methods include gravure coating, bar coating, printing, spraying, spin coating, blade coating, dip coating, and mold coating.

[0071] The perovskite light-absorbing layer may comprise a perovskite material represented by the following chemical formula 1 and benzylhydrazine oxalate.

[0072] [Chemical Formula 1]

[0073] FACsPbX3

[0074] In the above chemical formula 1, X is a monovalent anion. Specifically, X may include one or more monovalent anions selected from the following: iodide ion, bromide ion, chloride ion, fluoride ion, thiocyanate ion, cyanate ion, selenocyanate ion, formate ion, and acetate ion.

[0075] As a preferred example, X can be I. x Br 3-x (0≤x≤3). Furthermore, as a preferred embodiment of the above chemical formula 1, it can be FACsPbI. x Br 3-x (0≤x≤3).

[0076] Specifically, the perovskite light-absorbing layer may comprise a perovskite material represented by the above chemical formula 1 and benzylhydrazine oxalate in a weight ratio of 1:0.0001 to 0.002, preferably 1:0.0003 to 0.0014, more preferably 1:0.0004 to 0.0008. If the weight ratio is less than 1:0.0001, the desired effect may be negligible; if the weight ratio is greater than 1:0.002, it may act as a defect.

[0077] The perovskite light-absorbing layer can be formed by coating or spin-coating a solution containing a perovskite material represented by the above chemical formula 1 and benzylhydrazine oxalate onto one surface of a first interface layer, followed by heat treatment. Furthermore, non-limiting examples of methods for forming the perovskite light-absorbing layer include coating and / or vacuum deposition methods, where the coating method can be gravure coating, bar coating, printing, spraying, spin coating, blade coating, dip coating, or mold coating.

[0078] Furthermore, there is no particular limitation on the thickness of the perovskite light-absorbing layer, but the thickness can preferably be from 100 nm to 800 nm, more preferably from 450 nm to 700 nm, and even more preferably from 550 nm to 700 nm.

[0079] The second interface layer plays a role in reducing defects in perovskites, blocking external deteriorating factors (such as moisture) to improve stability, and efficiently transporting electrons to the electron transport layer by controlling the work function.

[0080] Furthermore, the thickness of the second interface layer can be from 0.5 nm to 10 nm, preferably from 2 nm to 8 nm.

[0081] Furthermore, the surface roughness RMS (root mean square) of the second interface layer can be from 4.50 nm to 80.00 nm, preferably from 5.00 nm to 50.00 nm.

[0082] In addition, methods for forming the second interface layer include coating and vacuum deposition. Coating methods can include gravure coating, bar coating, printing, spraying, spin coating, blade coating, dip coating, and mold coating.

[0083] In addition, the second interface layer may contain one or more of lithium fluoride (LiF), magnesium fluoride (MgF2), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF3), and calcium fluoride (CaF2).

[0084] The intermediate layer may comprise a fullerene-based organic material. In this case, the fullerene-based organic material may include materials selected from C... 60 C 70 One or more of PC60BM and PC70BM, with C being preferred. 60 Methods for forming intermediate layers include coating and vacuum deposition. Examples of coating methods include gravure coating, bar coating, printing, spraying, spin coating, blade coating, dip coating, and mold coating.

[0085] In addition, the thickness of the intermediate layer can be from 2 nm to 20 nm, preferably from 10 nm to 15 nm.

[0086] The electron transport layer (ETL) is a layer that transports electrons formed in the perovskite light-absorbing layer while preventing the movement of holes, and may contain one or more of the following: tin oxide (SnO2), titanium dioxide (TiO2), zinc oxide (ZnO), barium tin oxide (BaSnO3), niobium hydroxide (NbOH), and niobium pentoxide (Nb2O5).

[0087] In addition, methods for forming electron transport layers include coating and / or vacuum deposition methods. Examples of coating methods include gravure coating, bar coating, printing, spraying, spin coating, blade coating, dip coating, and mold coating.

[0088] Furthermore, there is no particular limitation on the thickness of the electron transport layer, but the thickness can preferably be from 5 nm to 40 nm, more preferably from 15 nm to 35 nm.

[0089] Transparent electrodes can be formed on the electron transport layer by deposition. In this case, deposition can be carried out by general deposition methods used in the art, preferably by sputtering under conditions of process temperature of 100°C or lower, RF power of 100 W to 300 W, process pressure of 1 mTorr to 3 mTorr, and argon (Ar) flow rate of 10 sccm to 40 sccm.

[0090] In addition, transparent electrodes can have transparent films deposited on them, such as 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).

[0091] Furthermore, there is no particular limitation on the thickness of the transparent electrode, but the thickness can preferably be from 50 nm to 200 nm, more preferably from 50 nm to 140 nm.

[0092] Metal electrodes can be formed by patterning metallic material on a transparent electrode. Specifically, the patterning process mainly includes deposition, photolithography, and etching. A metal electrode can be formed on a transparent electrode by spreading metallic material in the form of a thin film on a substrate, printing a pattern using photolithography, and then removing the unwanted portions.

[0093] In this case, the metallic material may include one or more of the following: Pt, Au, Ni, Cu, Ag, In, Ru, Pd, Rh, Ir, Os, C, and conductive polymers.

[0094] Furthermore, there is no separate limitation on the thickness of the metal electrode, but its thickness can preferably be from 50 nm to 2.5 μm.

[0095] Meanwhile, the method for manufacturing tandem silicon / perovskite heterojunction solar cells according to the present invention includes steps 1 to 3.

[0096] First, step 1 of the method for manufacturing a tandem silicon / perovskite heterojunction solar cell may involve sequentially stacking a solar cell, a transparent conductive layer, a hole transport layer, and a first interface layer. In this case, the solar cell, transparent conductive layer, hole transport layer, and first interface layer are the same as described above.

[0097] Specifically, a transparent conductive layer can be formed on a solar cell using sputtering. Alternatively, a hole transport layer can be formed on the transparent conductive layer using coating, vacuum deposition, or other methods.

[0098] In addition, the first interface layer can be formed by the following steps: step (1): heating the hole transport layer, step (2): coating the heated hole transport layer with a P-type organic molecular SAM interface coating agent, and step (3): drying the coated P-type organic molecular SAM interface coating agent to form the first interface layer.

[0099] The heating in step (1) can be performed by heating the hole transport layer to 40°C to 100°C, preferably 40°C to 80°C, more preferably 45°C to 70°C, and even more preferably 50°C to 60°C.

[0100] The coating in step (2) can be performed by scraping, stencil coating, bar coating, gravure coating, spraying, inkjet printing or screen printing. Preferably, scraping, stencil coating or bar coating can be performed.

[0101] The P-type organic molecular SAM interface coating agent in step (2) comprises a PACz-based compound and a solvent. The PACz-based compound can be included at a concentration of 0.30 mg / mL to 10.00 mg / mL. In this case, if the concentration of the PACz-based compound is less than 0.30 mg / mL, the organic molecular SAM layer may not be sufficiently formed, which may cause problems in improving the efficiency of the solar cell. If the concentration of the PACz-based compound is greater than 10.00 mg / mL, the film may be coated too thickly.

[0102] Furthermore, the PACz compound may include one or more of the following: 2-PACz ([2-(9H-carbazole-9-yl)ethyl]phosphonic acid), MeO-2PACz, Br-2PACz, Me-4PACz, MeO-4PACz, 6-PACz, and Me-6PACz. Additionally, the solvent for the P-type organic molecular SAM interface coating agent may include one or more of methanol, ethanol, 1-propanol, and 1-butanol.

[0103] Step (3) is the process of drying the coating agent applied in step (2), which can be carried out by natural drying, oven heat treatment or hot plate heat treatment, but it is preferred to carry out natural drying without separate heat treatment.

[0104] Next, step 2 of the method for manufacturing tandem silicon / perovskite heterojunction solar cells can be performed by forming a perovskite light-absorbing layer on the first interface layer through a coating method.

[0105] The formed perovskite light-absorbing layer may contain a perovskite material represented by the following chemical formula 1 and benzylhydrazine oxalate.

[0106] [Chemical Formula 1]

[0107] FACsPbX3

[0108] In the above chemical formula 1, X is a monovalent anion.

[0109] Specifically, in the perovskite light-absorbing layer, the perovskite material represented by the above chemical formula 1 and benzylhydrazine oxalate can be mixed in a weight ratio of 1:0.0001 to 0.002, preferably 1:0.0003 to 0.0014, more preferably 1:0.0004 to 0.0008.

[0110] The perovskite light-absorbing layer can be formed by coating or spin-coating a solution containing a perovskite material represented by the above chemical formula 1 and benzylhydrazine oxalate onto one surface of a first interface layer, followed by heat treatment. Furthermore, non-limiting examples of methods for forming the perovskite light-absorbing layer include coating and / or vacuum deposition methods, where the coating method can be gravure coating, bar coating, printing, spraying, spin coating, blade coating, dip coating, or mold coating.

[0111] Finally, step 3 of the method for manufacturing a tandem silicon / perovskite heterojunction solar cell can sequentially form a second interface layer, an intermediate layer, an electron transport layer, a transparent electrode, and a metal electrode on the perovskite light-absorbing layer. In this case, the second interface layer, intermediate layer, electron transport layer, transparent electrode, and metal electrode are the same as described above.

[0112] A second interface layer can be formed on the perovskite light-absorbing layer by coating and / or deposition methods (vacuum deposition, thermal deposition, vacuum thermal deposition, etc.). An intermediate layer can be formed on the second interface layer by coating and / or deposition methods (vacuum deposition, thermal deposition, vacuum thermal deposition, etc.). An electron transport layer can be formed on the intermediate layer by coating and / or vacuum deposition. A transparent electrode can be formed on the electron transport layer by deposition. Furthermore, a metal electrode can be formed by patterning a metallic material on the transparent electrode. In this case, the coating method can be gravure coating, rod coating, printing, spraying, spin coating, blade coating, dip coating, or mold coating.

[0113] The invention will be described in more detail below by way of examples, but the following examples do not limit the scope of the invention and should be interpreted as helpful in understanding the invention.

[0114] Preparation Example 1: Preparation of P-type organic molecular SAM interfacial coating agent

[0115] P-type organic molecular SAM interface coating agent was prepared by mixing 2-PACz ([2-(9H-carbazole-9-yl)ethyl]phosphonic acid) in 99% pure ethanol solvent at a concentration of 2.75 mg / mL.

[0116] Example 1: Fabrication of tandem silicon / perovskite heterojunction solar cells

[0117] (1) A silicon solar cell doped with n-type or p-type impurities (thickness: 180 μm) was prepared, and the SiOx oxide film was removed by hydrofluoric acid treatment. Then, the remaining hydrofluoric acid was removed by using ultrapure water. A 20 nm thick transparent conductive layer (ITO) was formed on the oxide-removed silicon solar cell by sputtering (process conditions: process temperature 25°C to 45°C, RF power 100 W to 250 W, process pressure 2.2 mTorr to 2.4 mTorr, argon flow rate 10 sccm to 40 sccm).

[0118] (2) Next, a 20 nm thick hole transport layer (NiOx) is formed on the transparent conductive layer by sputtering vacuum deposition.

[0119] (3) Next, the hole transport layer is heated to a temperature of 50°C. Then, the P-type organic molecular SAM interface coating agent prepared in Preparation Example 1 is applied to the heated hole transport layer at a coating speed of 10 mm / s to an average thickness of 3.1 nm. The coating is then allowed to dry naturally, thereby forming the first interface layer by the coating method.

[0120] (4) Next, a precursor solution prepared by dissolving a perovskite material represented by the following chemical formula 1-1 and benzylhydrazine oxalate in a mixed solution containing dimethylformamide (DMF) and dimethylmalonide (N,N'-dimethylmalonide (DMPU)) is coated onto the first interface layer, followed by heat treatment at 150°C for 10 minutes and then at 115°C for 20 minutes to form a perovskite light-absorbing layer containing benzylhydrazine oxalate, with a thickness of 600 nm and a perovskite crystal structure. In this case, the precursor solution contains a perovskite material represented by the following chemical formula 1-1 and benzylhydrazine oxalate in a weight ratio of 1:0.0005.

[0121] [Chemical Formula 1-1]

[0122] FACsPb(I aBr b )3

[0123] In the above chemical formula 1-1, the molar ratio of a to b is 8:2.

[0124] (5) Next, a second interface layer (LiF) with an average thickness of 3.1 nm is formed on the perovskite light-absorbing layer by vacuum thermal evaporation.

[0125] (6) Next, C is deposited on the second interface layer using a thermal evaporation method. 60 Fullerenes are used to form an intermediate layer with an average thickness of 13 nm.

[0126] (7) Next, a SnO2 nanocolloid solution is spin-coated onto the intermediate layer to form an electron transport layer (SnO2) with a thickness of 15 nm.

[0127] (8) Next, a transparent electrode (ITO) with a thickness of 70 nm is formed on the electron transport layer by sputtering (process conditions: process temperature 95°C to 98°C, RF power 100 W to 200 W, process pressure 2.2 mTorr to 2.4 mTorr, argon flow rate 10 sccm to 40 sccm).

[0128] (9) Finally, in 1×10 -7 Under pressure, silver (Ag) is deposited on a transparent electrode to a thickness of 100 nm to form a metal electrode, thereby fabricating a tandem silicon / perovskite heterojunction solar cell in which silicon solar cells, a transparent conductive layer, a hole transport layer, a first interface layer, a perovskite light-absorbing layer, a second interface layer, an intermediate layer, an electron transport layer, a transparent electrode, and a metal electrode are sequentially stacked.

[0129] Comparative Example 1: Fabrication of tandem silicon / perovskite heterojunction solar cells

[0130] The tandem silicon / perovskite heterojunction solar cell was fabricated using the same method as in Example 1. However, unlike Example 1, the precursor solution used to form the perovskite light-absorbing layer was prepared by dissolving the perovskite material represented by the above chemical formula 1-1 in a mixed solution containing dimethylformamide (DMF) and dimethylmalonide (N,N'-dimethylmalonide (DMPU)).

[0131] Comparative Example 2: Fabrication of tandem silicon / perovskite heterojunction solar cells

[0132] The tandem silicon / perovskite heterojunction solar cell was fabricated using the same method as in Example 1. However, unlike Example 1, the precursor solution used to form the perovskite light-absorbing layer was prepared by dissolving the perovskite material represented by the above chemical formula 1-1 and benzylhydrazine hydrochloride in a mixed solution containing dimethylformamide (DMF) and dimethylmalonide (N,N'-dimethylmalonide (DMPU)). In this case, the precursor solution contained the perovskite material represented by the above chemical formula 1-1 and benzylhydrazine hydrochloride in a weight ratio of 1:0.0005.

[0133] Example 2: Fabrication of tandem silicon / perovskite heterojunction solar cells

[0134] The tandem silicon / perovskite heterojunction solar cell was fabricated using the same method as in Example 1. However, unlike Example 1, the precursor solution used to form the perovskite light-absorbing layer contained perovskite material represented by chemical formula 1-1 and benzylhydrazine oxalate in a weight ratio of 1:0.0002.

[0135] Example 3: Fabrication of tandem silicon / perovskite heterojunction solar cells

[0136] The tandem silicon / perovskite heterojunction solar cell was fabricated using the same method as in Example 1. However, unlike Example 1, the precursor solution used to form the perovskite light-absorbing layer contained perovskite material represented by the above chemical formula 1-1 and benzylhydrazine oxalate in a weight ratio of 1:0.0017.

[0137] Experimental Example 1: Evaluation of the performance and long-term storage stability of solar cells

[0138] For each tandem silicon / perovskite heterojunction solar cell manufactured in Examples 1 to 3 and Comparative Examples 1 to 2, the efficiency was measured using a solar energy simulation apparatus and a JV Wavelabs apparatus, and the initial JV curves were used. After storing the cells in an atmospheric pressure desiccator for 30 days, the JV curves were measured to evaluate the changes in the characteristics of the solar cells after aging, and the results are shown in Table 1 below.

[0139] [Table 1]

[0140] As can be determined in Table 1 above, the tandem silicon / perovskite heterojunction solar cells manufactured in Examples 1 to 3 have higher long-term storage stability compared to the tandem silicon / perovskite heterojunction solar cells manufactured in Comparative Example 1.

[0141] The specific implementation schemes have been described and illustrated above. However, the invention is not limited to the above-described implementation schemes, and those skilled in the art can make various modifications and implementation schemes without departing from the spirit of the technical concept described in the foregoing claims.

Claims

1. A stacked silicon / perovskite heterojunction solar cell, wherein the solar cell 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 layer, a transparent electrode, and a metal electrode are sequentially stacked. The perovskite light-absorbing layer comprises a perovskite material represented by the following chemical formula 1 and benzylhydrazine oxalate: [Chemical Formula 1] FACsPbX3 In the above chemical formula 1, X is a monovalent anion.

2. The tandem silicon / perovskite heterojunction solar cell according to claim 1, wherein the perovskite light-absorbing layer comprises the perovskite material represented by the above chemical formula 1 and the benzylhydrazine oxalate in a weight ratio of 1:0.0001 to 0.

002.

3. The tandem silicon / perovskite heterojunction solar cell according to claim 1, wherein the average thickness of the perovskite light-absorbing layer is 450 nm to 700 nm.

4. The tandem silicon / perovskite heterojunction solar cell according to claim 1 further comprises: A first interface layer between the hole transport layer and the perovskite light absorption layer.

5. The tandem silicon / perovskite heterojunction solar cell according to claim 4, wherein the first interface layer comprises a p-type organic molecular SAM interface coating agent.

6. The tandem silicon / perovskite heterojunction solar cell according to claim 4, wherein the thickness of the first interface layer is 0.5 nm to 10 nm.

7. The tandem silicon / perovskite heterojunction solar cell according to claim 1, further comprising: A second interface layer between the perovskite light-absorbing layer and the electron transport layer.

8. The tandem silicon / perovskite heterojunction solar cell according to claim 7, wherein the second interface layer comprises one or more of lithium fluoride (LiF), magnesium fluoride (MgF2), cesium fluoride (CsF), sodium fluoride (NaF), potassium fluoride (KF), aluminum fluoride (AlF3), and calcium fluoride (CaF2).

9. The tandem silicon / perovskite heterojunction solar cell according to claim 7, wherein the thickness of the second interface layer is 0.5 nm to 10 nm.

10. The tandem silicon / perovskite heterojunction solar cell according to claim 7, further comprising: An intermediate layer between the second interface layer and the electron transport layer.

11. The tandem silicon / perovskite heterojunction solar cell according to claim 10, wherein the intermediate layer comprises a fullerene series organic material.

12. A method for manufacturing a tandem silicon / perovskite heterojunction solar cell, the method comprising: Step 1: Stack the solar cell, transparent conductive layer, hole transport layer and first interface layer sequentially; Step 2: Form a perovskite light-absorbing layer on the first interface layer by coating method; as well as Step 3: Sequentially form a second interface layer, an intermediate layer, an electron transport layer, a transparent electrode, and a metal electrode on the perovskite light-absorbing layer. The perovskite light-absorbing layer comprises a perovskite material represented by the following chemical formula 1 and benzylhydrazine oxalate: [Chemical Formula 1] FACsPbX3 In the above chemical formula 1, X is a monovalent anion.

13. The method according to claim 12, wherein the coating method is gravure coating, bar coating, printing, spraying, spin coating, scraping coating, dip coating, or mold coating.

14. The method according to claim 12, wherein the perovskite material represented by the above chemical formula 1 and the benzylhydrazine oxalate are mixed in a weight ratio of 1:0.0001 to 0.002 in the perovskite light-absorbing layer.

15. The method of claim 12, wherein the first interface layer is formed by a process comprising the following steps: Step (1): Heat the hole transport layer; Step (2): Coating a P-type organic molecular SAM interface coating agent onto the heated hole transport layer; and Step (3): Dry the coated P-type organic molecular SAM interface coating agent to form the first interface layer.

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