Perovskite solar cell and tandem solar cell comprising same

Abstract

An embodiment of the present invention relates to a perovskite solar cell and a tandem solar cell comprising same, the perovskite solar cell comprising: a substrate; a first electrode disposed on the substrate; a second electrode disposed to face the first electrode; a light-absorbing layer disposed between the first electrode and the second electrode; and a hole transport layer between the second electrode and the light-absorbing layer, wherein the hole transport layer comprises a self-assembled organic material. The hole transport layer comprises a self-assembled monolayer (SAM) material and nanoparticles, thereby improving performance of a solar cell device.

Description

Perovskite solar cell and tandem solar cell including the same

[0001] The present invention relates to a perovskite solar cell and a tandem solar cell including the same.

[0002] Tandem solar cells are an attempt to minimize thermalization loss by effectively utilizing solar energy over a wide wavelength range through the vertical stacking of light-absorbing layers with different bandgaps. Specifically, tandem solar cells can overcome the efficiency limitations of single-junction solar cells by minimizing the loss of excess electron-hole energy as heating energy generated when photons with energy greater than the bandgap are absorbed by the light-absorbing layers. This is achieved by having light-absorbing layers with different bandgaps absorb sunlight separately according to wavelength ranges. Recently, as interest in tandem solar cells has increased as the most feasible next-generation solar cells, various structures of tandem solar cell technology are being researched.

[0003] In the perovskite solar cell according to an embodiment of the present invention, a perovskite thin film can be easily formed through a structural change of the hole transport layer, and at the same time, the performance of the solar cell device can be improved.

[0004] An embodiment of the present invention for achieving the above-described purpose discloses a perovskite solar cell comprising a substrate, a first electrode disposed on the substrate, a second electrode disposed opposite to the first electrode, a light absorption layer disposed between the first electrode and the second electrode, and a hole transport layer between the second electrode and the light absorption layer, wherein the hole transport layer comprises a self-assembled organic material.

[0005] Another embodiment of the present invention for achieving the above-described purpose discloses a tandem solar cell comprising a lower cell, a perovskite upper cell disposed on the lower cell, and a connecting layer disposed between the lower cell and the perovskite upper cell, wherein the perovskite upper cell comprises a hole transport layer and the hole transport layer comprises a self-assembled organic material.

[0006] In a tandem solar cell according to an embodiment of the present invention, by mixing a self-assembled monolayers (SAM) material and nanoparticles as a hole transport layer, a perovskite thin film can be easily formed on the hole transport layer, and at the same time, the performance of the solar cell device can be improved.

[0007] FIG. 1 is a cross-sectional view schematically illustrating an example of a perovskite solar cell according to one embodiment of the present invention.

[0008] FIG. 2 is a cross-sectional view schematically illustrating an example of a tandem solar cell according to an embodiment of the present invention.

[0009] Figure 3 is a cross-sectional view schematically illustrating another example of the tandem solar cell of Figure 2.

[0010] Figure 4 is a graph showing the Fermi level of the second hole transport layer.

[0011] One embodiment of the present invention discloses a perovskite solar cell comprising a substrate, a first electrode disposed on the substrate, a second electrode disposed opposite to the first electrode, a light absorption layer disposed between the first electrode and the second electrode, and a hole transport layer between the second electrode and the light absorption layer, wherein the hole transport layer comprises a self-assembled organic material.

[0012] In the present embodiment, the hole transport layer comprises a first hole transport layer and a second hole transport layer disposed on the first hole transport layer, wherein the first hole transport layer comprises a metal oxide or a metal, and the second hole transport layer may comprise a self-assembled organic material.

[0013] In the present embodiment, the second hole transport layer further comprises nanoparticles, and the nanoparticles may comprise inorganic materials.

[0014] In this embodiment, the inorganic material may include silica (SiO2) or aluminum oxide (Al2O3).

[0015] In this embodiment, the second hole transport layer may comprise a single layer in which the self-assembled organic material and the nanoparticle are mixed.

[0016] In this embodiment, the self-assembled organic material may include phosphonic acid or carbazole.

[0017] In this embodiment, the self-assembled organic material may include one or more selected from 2PACz, MeO-2PACz, Me-4PACz, Me-2PACz Br-2PACz, 4PADCB, and 3PATAT-C3.

[0018] Another embodiment of the present invention discloses a tandem solar cell comprising a lower cell, a perovskite upper cell disposed on the lower cell, and a connecting layer disposed between the lower cell and the perovskite upper cell, wherein the perovskite upper cell comprises a hole transport layer and the hole transport layer comprises a self-assembled organic material.

[0019] In the present embodiment, the hole transport layer comprises a first hole transport layer and a second hole transport layer disposed on the first hole transport layer, wherein the first hole transport layer comprises a metal oxide or a metal, and the second hole transport layer may comprise a self-assembled organic material.

[0020] In the present embodiment, the second hole transport layer further comprises nanoparticles, and the nanoparticles may comprise inorganic materials.

[0021] In this embodiment, the inorganic material may include silica (SiO2) or aluminum oxide (Al2O3).

[0022] In this embodiment, the second hole transport layer may comprise a single layer in which the self-assembled organic material and the nanoparticle are mixed.

[0023] In this embodiment, the self-assembled organic material may include phosphonic acid or carbazole.

[0024] In this embodiment, the self-assembled organic material may include one or more selected from 2PACz, MeO-2PACz, Me-4PACz, Me-2PACz Br-2PACz, 4PADCB, and 3PATAT-C3.

[0025] In the present embodiment, the perovskite upper cell may include a perovskite light absorption layer disposed on the second hole transport layer, a first electron transport layer disposed on the perovskite light absorption layer, and an electrode disposed on the first electron transport layer.

[0026] The present invention is capable of various modifications and may have various embodiments; specific embodiments are illustrated in the drawings and described in detail in the detailed description. The effects and features of the present invention, and the methods for achieving them, will become clear by referring to the embodiments described below in detail together with the drawings. However, the present invention is not limited to the embodiments disclosed below but can be implemented in various forms.

[0027] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. When describing with reference to the drawings, identical or corresponding components are given the same reference numerals, and redundant descriptions thereof will be omitted.

[0028] In the following embodiments, terms such as first, second, etc. are used not in a limiting sense, but for the purpose of distinguishing one component from another component.

[0029] In the following examples, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0030] In the following embodiments, terms such as "include" or "have" mean that the features or components described in the specification are present, and do not preclude the possibility that one or more other features or components may be added.

[0031] In the drawings, the size of components may be exaggerated or reduced for convenience of explanation. For example, the size and thickness of each component shown in the drawings are depicted arbitrarily for convenience of explanation, so the present invention is not necessarily limited to what is illustrated.

[0032] In the following embodiments, the x-axis, y-axis, and z-axis are not limited to three axes in an orthogonal coordinate system and can be interpreted in a broader sense that includes them. For example, the x-axis, y-axis, and z-axis may be orthogonal to each other, but they may also refer to different directions that are not orthogonal to each other.

[0033] Where an embodiment can be implemented differently, a specific process sequence may be performed differently from the order described. For example, two processes described consecutively may be performed substantially simultaneously or proceed in the reverse order of the description.

[0034] FIG. 1 is a cross-sectional view schematically illustrating an example of a perovskite solar cell according to one embodiment of the present invention.

[0035] A perovskite solar cell (1) may include a substrate (S), a first electrode (60), a hole transport layer, a light absorption layer (20), and a second electrode (70), and the hole transport layer may include a first hole transport layer (10) and a second hole transport layer (30) disposed on the first hole transport layer (10).

[0036] Additionally, it may include a first electron transport layer (40) disposed between the second electrode (70) and the photoactive layer (20), and may further include a second electron transport layer (45) disposed on the first electron transport layer (40).

[0037] Additionally, as an optional embodiment, a passivation layer (50) may be further included between the light absorption layer (20) and the first electron transport layer (40).

[0038] Additionally, as an optional embodiment, a transparent electrode (65) may be further included between the first electron transport layer (40) and the electrode (70), and an anti-reflection layer (70) disposed on the transparent electrode (65) may be further included.

[0039] Meanwhile, the perovskite solar cell according to one embodiment of the present invention illustrated in FIG. 1 relates to a pin planar structure among the four structures of a general perovskite solar cell, namely, nip mesoscopic, nip planar, pin planar, and pin mesoscopic structures.

[0040] However, the structure of the perovskite solar cell illustrated in FIG. 1 is one embodiment and is not limited thereto, and the composition of the composite layer according to the embodiment of the present invention can be applied in the same way to perovskite solar cells modified with a different structure, a different stacking order, or a different configuration.

[0041] A substrate (S) may be placed on a bottom surface to form a perovskite solar cell (1) and may include any one selected from borosilicate glass, quartz glass, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polycarbonate (PC), polypropylene (PP), triacetylcellulose (TAC), or polyethersulfone (PES), but is not limited thereto.

[0042] The first electrode (60) can be formed on the substrate (S) and can be formed of a conductive material having light transparency.

[0043] For example, the first electrode (60) is formed from a conductive material and may include, for example, a transparent conductive oxide, a carbonaceous conductive material, and a metallic material. Specific examples of transparent conductive oxides include ITO (Indium Tin Oxide), ICO (Indium Cerium Oxide), IWO (Indium Tungsten Oxide), ZITO (Zinc Indium Tin Oxide), ZIO (Zinc Indium Oxide), ZTO (Zinc Tin Oxide), GITO (Gallium Indium Tin Oxide), GIO (Gallium Indium Oxide), GZO (Gallium Zinc Oxide), AZO (Aluminum doped Zinc Oxide), FTO (Fluorine Tin Oxide), ZnO, etc. Carbonaceous conductive materials may include, for example, graphene or carbon nanotubes, and metallic materials may include, for example, metal (Ag) nanowires or metal thin films with a multilayer structure such as Au / Ag / Cu / Mg / Mo / Ti. In this specification, the term "transparent" refers to the ability to transmit light to a certain degree or more, and is not necessarily interpreted to mean complete transparency. The materials described above are not necessarily limited to the embodiments described above and can be formed from various materials, and their structures can also be varied, such as being single-layer or multilayer.

[0044] The first hole transport layer (10) may be a layer disposed on the first electrode (60) to which holes formed in the perovskite light absorption layer (20) are transported. For example, the hole transport layer (10) may include one or more selected from tungsten oxide (WOx), molybdenum oxide (MoOx), vanadium oxide (V2O5), and nickel oxide (NiOx), and may also include at least one selected from the group consisting of monomolecular hole transport materials and polymeric hole transport materials, but is not limited thereto and any material used in the industry may be used. For example, spiro-MeOTAD [2,2',7,7'-tetrakis(N,Np-dimethoxy-phenylamino)-9,9'-spirobifluorene] may be used as the above-mentioned single-molecule hole transport material, and P3HT [poly(3-hexylthiophene)], PTAA (polytriarylamine), poly(3,4-ethylenedioxythiophene) or polystyrene sulfonate (PEDOT:PSS) may be used as the above-mentioned polymer hole transport material, but are not limited thereto.

[0045] Meanwhile, the first hole transport layer (10) may further include a doping material. As an example, the doping material may be a doping material selected from the group consisting of Li-based dopants, Co-based dopants, Cu-based dopants, Cs-based dopants, and combinations thereof, but is not limited thereto.

[0046] The second hole transport layer (30) may include self-assembled monolayers (SAM). In this case, the self-assembled monolayers adsorb to the surface of the first hole transport layer (10) to form a monolayer, and in this case, the first hole transport layer (10) may be formed of a semi-conductor metal oxide or a metal material.

[0047] The second hole transport layer (30) may, for example, include a self-assembled organic material, specifically a self-assembled organic material having a phosphate acid functional group or a carbazole backbone, more specifically, may form a self-assembled monolayer by including one or more selected from 2PACz, MeO-2PACz, Me-4PACz, Me-2PACz, Br-2PACz, 4PADCB, and 3PATAT-C3, and may additionally include nanoparticles. For example, the nanoparticles may include an inorganic material, specifically silica (SiO2) or aluminum oxide (Al2O3).

[0048] Meanwhile, if the second hole transport layer (30) is formed only as a self-assembled monolayer without containing nanoparticles, it may have hydrophobicity, making it difficult to form a hydrophilic perovskite light absorption layer (20) on the second hole transport layer (30). Specifically, the perovskite light absorption layer (20) can be formed by applying a precursor solution, in which a perovskite precursor material is dissolved in a solvent, using a blade process. At this time, the solvent used to dissolve the perovskite precursor material may exhibit hydrophilicity, so the perovskite precursor solution may have hydrophilicity. Therefore, forming a perovskite light absorption layer (20) on the second hole transport layer (30), which is formed only as a self-assembled monolayer exhibiting hydrophobicity, may be difficult due to the wetting problem between the hydrophilic perovskite solvent and the hydrophobic self-assembled monolayer.

[0049] To solve this problem, there is also a method of separately forming a nanoparticle layer on the second hole transport layer (30), but in this case, the Fermi level equilibrium between the nanoparticles and the self-assembled material does not occur, and there is a problem that the performance of the solar cell device is reduced due to the field influence of the fixed charge.

[0050] Meanwhile, the second hole transport layer (30) according to an embodiment of the present invention contains a self-assembled material and nanoparticles, and for example, the nanoparticles are uniformly distributed in the self-assembled material so that the self-assembled material and the nanoparticles form a single layer, thereby overcoming the problem of reduced solar cell device performance due to fixed charge and making it easy to form a perovskite light absorption layer (20) on the hydrophobic self-assembled single layer using a hydrophilic perovskite precursor solution.

[0051] The perovskite light absorption layer (20) can be formed on the second hole transport layer (30), and, for example, can perform the role of separating hole-electron pairs generated by receiving light energy from the sun into electrons or holes. At this time, electrons generated in the perovskite light absorption layer (20) are transferred to the first electron transport layer (40) described later, and holes generated in the perovskite light absorption layer (20) can be transferred to the first hole transport layer (10) and the second hole transport layer (30).

[0052] For example, the perovskite light-absorbing layer (20) may have a structure represented by the chemical formula ABX3 (wherein A is a monovalent organic cation or metal cation, B is a divalent metal cation, and X is a halogen anion).

[0053] As a specific example, the perovskite light-absorbing layer (20) may include organic halide perovskites such as methyl ammonium iodide (MAI) and formamidinium iodide (FAI), or metal halide perovskites such as lead iodide (PbI2), bromine iodide (PbBr), and lead chloride (PbCl2), and may be a multilayer stacked structure including at least one of organic halide perovskites or metal halide perovskites. More specifically, the perovskite light-absorbing layer (20) may be CH3NH3PbI3, CH3NH3PbI xCl 3-x , CH3NH3PbI x Br 3-x , CH3NH3PbCl x Br 3-x , HC(NH2)2PbI3, HC(NH2)2PbI x Cl 3-x , HC(NH2)2PbI x Br 3-x , HC(NH2)2PbCl x Br 3-x , (CH3NH3)(HC(NH2)2) 1-y PbI3, (CH3NH3)(HC(NH2)2) 1-y PbI x Cl 3-x , (CH3NH3)(HC(NH2)2) 1-y PbI x Br 3-x , or (CH3NH3)(HC(NH2)2) 1-y PbCl x Br 3-x It may include the back (0≤x, y≤1).

[0054] The first electron transport layer (40) may be formed from a fullerene-based material, for example, and the thickness of the first electron transport layer (40) formed from a fullerene-based material may be formed to be 5 nm to 30 nm. In this case, if it is formed with a thickness thinner than 5 nm, the hole blocking characteristics may be reduced, and if it is formed with a thickness thicker than 30 nm, the electron transport characteristics may be reduced, and thus the performance of the solar cell device may be reduced.

[0055] As an optional embodiment, a second electron transport layer (45) may be further formed on the first electron transport layer (40).

[0056] The second electron transport layer (45) may include, for example, one or more selected from SnOx, TiOx, ZnOx, WOx, NbOx, InOx, AlOx, HfOx, BaSnOx, ZrOx, VOx, and CeOx, and specifically, may include SnOx. In addition, the first electron transport layer (40) may be formed using various methods, and may be formed at a low temperature using atomic layer deposition (ALD) to stably secure the desired shape and characteristics.

[0057] Meanwhile, the second electron transport layer (45) can also serve as a buffer layer.

[0058] As an optional embodiment, a pavement layer (50) may be disposed between the first electron transport layer (40) and the perovskite light absorption layer (20).

[0059] The pavement layer (50) may include, for example, LiF, and can reduce or prevent oxidation of the perovskite compound of the perovskite light absorption layer (20) by the material of the first electron transport layer (40), for example, a metal oxide.

[0060] A second electrode (70) may be placed on the first electron transport layer (40).

[0061] The second electrode (70) serves to allow the tandem solar cell to be electrically connected to the outside, and can be formed of a metallic material such as silver (Ag), gold (Au), copper (Cu), magnesium (Mg), molybdenum (Mo), and titanium (Ti), for example.

[0062] Meanwhile, the second electrode (70) can be formed in a grid pattern so that sunlight can enter the cell.

[0063] As an optional embodiment, a transparent electrode (65) may be formed between the first electron transport layer (40) and the second electrode (70).

[0064] The transparent electrode (65) can be formed on the electron transport layer (40) using a conductive material that is transparent, and may include, for example, a transparent conductive oxide, a carbonaceous conductive material, and a metallic material. As for the transparent conductive oxide, for example, ITO (Indium Tin Oxide), ICO (Indium Cerium Oxide), IWO (Indium Tungsten Oxide), ZITO (Zinc Indium Tin Oxide), ZIO (Zinc Indium Oxide), ZTO (Zinc Tin Oxide), GITO (Gallium Indium Tin Oxide), GIO (Gallium Indium Oxide), GZO (Gallium Zinc Oxide), AZO (Aluminum doped Zinc Oxide), FTO (Fluorine Tin Oxide), ZnO, etc. may be used. Carbonaceous conductive materials may include, for example, graphene or carbon nanotubes, and metallic materials may include, for example, metal nanowires or multilayer metal thin films such as Au / Ag / Cu / Mg / Mo / Ti. In this specification, the term "transparent" refers to the ability to transmit light to a certain degree or more, and is not necessarily interpreted to mean complete transparency. The materials described above are not necessarily limited to the embodiments described above and can be formed from various materials, and their structures can also be varied, such as being single-layer or multilayer.

[0065] Additionally, as an optional embodiment, an anti-reflection layer (80) may be further formed on the transparent electrode (65).

[0066] The anti-reflection layer (80) can prevent sunlight irradiated onto the perovskite solar cell (1) from being reflected, thereby improving the transmittance of sunlight and increasing the efficiency of the perovskite solar cell (1).

[0067] For example, the anti-reflection film (80) may include a fluorine (F) material with high light transmittance and a very low refractive index, and may include LiF as an optional embodiment.

[0068] As a result, in the perovskite solar cell according to an embodiment of the present invention, a SAM (Self-assembled monolayers) material and nanoparticles are mixed as a second hole transport layer, so that a perovskite thin film can be easily formed on the hydrophobic second hole transport layer, and at the same time, the performance of the solar cell device can be improved.

[0069] FIG. 2 is a cross-sectional view schematically illustrating an example of a tandem solar cell according to an embodiment of the present invention.

[0070] Referring to FIG. 2, a perovskite tandem solar cell (1000) may include a silicon bottom cell (100), a perovskite top cell (200), and a connecting layer (10) connecting the silicon bottom cell (100) and the perovskite top cell (200).

[0071] First, the silicon lower cell (100) will be described.

[0072] The silicon bottom cell (100) may include a silicon solar cell, for example, a silicon solar cell having a bandgap of 1.0 eV to 1.2 eV, and may further include a silicon layer (110) and an emitter layer (115) disposed on the silicon layer (110).

[0073] The silicon layer (110) may have one of the structures of a known silicon solar cell and is not limited to a specific structure. For example, the silicon layer (110) may include a crystalline silicon substrate (not shown), a p-type amorphous or crystalline silicon layer (not shown), an n-type amorphous or crystalline silicon layer (not shown), and an amorphous intrinsic silicon layer (not shown), and may further include additional layers as needed, although not shown in the drawings.

[0074] Meanwhile, at least a portion of the lower surface of the silicon lower cell (100) may be textured with pyramid-shaped irregularities to improve light efficiency. That is, an irregular surface is formed in the direction of incident light, and by increasing the path of light incident on the silicon layer (110) through the light scattering effect of the light incident through the irregular surface, the light collection is improved, thereby increasing the absorption rate of sunlight and thereby achieving a high current value. At this time, the pyramid angle of the surface of the texturing may exceed 5°, and preferably, the pyramid angle of the surface may exceed 30°.

[0075] Next, the perovskite upper cell (200) is described.

[0076] The perovskite upper cell (200) is a cell connected to the silicon lower cell (100) described above, and may have a band gap of less than 1.66 eV and may include a hole transport layer, a perovskite light absorption layer (220), a first electron transport layer (240), and an electrode (270), and the hole transport layer may include a first hole transport layer (210) and a second hole transport layer (230) disposed on the first hole transport layer (210).

[0077] As an optional embodiment, the perovskite upper cell (200) may further include a passivation layer (250) between the perovskite light absorption layer (220) and the first electron transport layer (240), and may further include a second electron transport layer (245) disposed on the first electron transport layer (240).

[0078] Additionally, as an optional embodiment, a transparent electrode (260) may be further included between the first electron transport layer (240) and the electrode (270), and an anti-reflection layer (270) disposed on the transparent electrode (260) may be further included.

[0079] The first hole transport layer (210) may be a layer formed on a silicon bottom cell (100) to which holes formed in the perovskite light absorption layer (220) described later are transported. For example, the hole transport layer (210) may include one or more selected from tungsten oxide (WOx), molybdenum oxide (MoOx), vanadium oxide (V2O5), and nickel oxide (NiOx), and may also include at least one selected from the group consisting of monomolecular hole transport materials and polymeric hole transport materials, but is not limited thereto and any material used in the industry may be used. For example, spiro-MeOTAD [2,2',7,7'-tetrakis(N,Np-dimethoxy-phenylamino)-9,9'-spirobifluorene] may be used as the above-mentioned single-molecule hole transport material, and P3HT [poly(3-hexylthiophene)], PTAA (polytriarylamine), poly(3,4-ethylenedioxythiophene) or polystyrene sulfonate (PEDOT:PSS) may be used as the above-mentioned polymer hole transport material, but are not limited thereto.

[0080] Meanwhile, the hole transport layer (210) may further include a doping material. For example, the doping material may be a doping material selected from the group consisting of Li-based dopants, Co-based dopants, Cu-based dopants, Cs-based dopants, and combinations thereof, but is not limited thereto.

[0081] The second hole transport layer (230) may include self-assembled monolayers (SAM). In this case, the self-assembled monolayers adsorb to the surface of the first hole transport layer (220) to form a monolayer, and in this case, the first hole transport layer (220) may be formed of a semi-conductor metal oxide or a metal material.

[0082] The second hole transport layer (230) may, for example, include a self-assembled organic material, and specifically, may include a self-assembled organic material having a phosphate acid functional group or a carbazole backbone, and more specifically, may form a self-assembled monolayer by including one or more selected from 2PACz, MeO-2PACz, Me-4PACz, Me-2PACz, Br-2PACz, 4PADCB and 3PATAT-C3, and may additionally include nanoparticles. For example, the nanoparticles may include an inorganic material, and specifically, may include silica (SiO2) or aluminum oxide (Al2O3).

[0083] Meanwhile, if the second hole transport layer (230) is formed only as a self-assembled monolayer without containing nanoparticles, it may have hydrophobicity, making it difficult to form a hydrophilic perovskite light absorption layer (220) on the second hole transport layer (230). Specifically, the perovskite light absorption layer (220) can be formed by applying a precursor solution, in which a perovskite precursor material is dissolved in a solvent, using a blade process. At this time, the solvent used to dissolve the perovskite precursor material may exhibit hydrophilicity, so the perovskite precursor solution may have hydrophilicity. Therefore, forming a perovskite light absorption layer (220) on the second hole transport layer (230), which is formed only as a self-assembled monolayer exhibiting hydrophobicity, may be difficult due to the wetting problem between the hydrophilic perovskite solvent and the hydrophobic self-assembled monolayer.

[0084] To solve this problem, there is also a method of separately forming a nanoparticle layer on the second hole transport layer (230), but in this case, the Fermi level equilibrium between the nanoparticles and the self-assembled material does not occur, and there is a problem that the performance of the solar cell device is reduced due to the field influence of the fixed charge.

[0085] Meanwhile, the second hole transport layer (230) according to the embodiment of the present invention allows nanoparticles to be uniformly distributed in the self-assembled material, thereby forming a single layer of the self-assembled material and nanoparticles, which overcomes the problem of reduced solar cell device performance due to fixed charge, and enables the easy formation of a perovskite light absorption layer (220) on the hydrophobic self-assembled single layer using a hydrophilic perovskite precursor solution.

[0086] The perovskite light absorption layer (220) can be formed on the second hole transport layer (230) and, for example, can perform the role of separating hole-electron pairs generated by receiving light energy from the sun into electrons or holes. At this time, electrons generated in the perovskite light absorption layer (220) are transferred to the first electron transport layer (240) described later, and holes generated in the perovskite light absorption layer (220) can be transferred to the first hole transport layer (210) and the second hole transport layer (230).

[0087] For example, the perovskite light-absorbing layer (220) may have a structure represented by the chemical formula ABX3 (wherein A is a monovalent organic cation or metal cation, B is a divalent metal cation, and X is a halogen anion).

[0088] As a specific example, the perovskite light-absorbing layer (400) may include organic halide perovskites such as methyl ammonium iodide (MAI) and formamidinium iodide (FAI), or metal halide perovskites such as lead iodide (PbI2), bromine iodide (PbBr), and lead chloride (PbCl2), and may be a multilayer stacked structure including at least one of organic halide perovskites or metal halide perovskites. More specifically, the perovskite light-absorbing layer (400) may be CH3NH3PbI3, CH3NH3PbI x Cl 3-x, CH3NH3PbI x Br 3-x , CH3NH3PbCl x Br 3-x , HC(NH2)2PbI3, HC(NH2)2PbI x Cl 3-x , HC(NH2)2PbI x Br 3-x , HC(NH2)2PbCl x Br 3-x , (CH3NH3)(HC(NH2)2) 1-y PbI3, (CH3NH3)(HC(NH2)2) 1-y PbI x Cl 3-x , (CH3NH3)(HC(NH2)2) 1-y PbI x Br 3-x , or (CH3NH3)(HC(NH2)2) 1-y PbCl x Br 3-x It may include the back (0≤x, y≤1).

[0089] The first electron transport layer (240) may be formed from a fullerene-based material, for example, and the thickness of the first electron transport layer (240) formed from a fullerene-based material may be formed to be 5 nm to 30 nm. In this case, if it is formed to a thickness thinner than 5 nm, the hole blocking characteristics may be reduced, and if it is formed to a thickness thicker than 30 nm, the electron transport characteristics may be reduced, and thus the performance of the solar cell device may be reduced.

[0090] As an optional embodiment, a second electron transport layer (245) may be further formed on the first electron transport layer (240).

[0091] The second electron transport layer (245) may include, for example, one or more selected from SnOx, TiOx, ZnOx, WOx, NbOx, InOx, AlOx, HfOx, BaSnOx, ZrOx, VOx, and CeOx, and specifically, may include SnOx. In addition, the first metal oxide layer (A) may be formed using various methods, and may be formed at a low temperature using atomic layer deposition (ALD) to stably secure the desired shape and characteristics.

[0092] Meanwhile, the second electron transport layer (245) can also serve as a buffer layer.

[0093] As an optional embodiment, a pavement layer (250) may be included between the first electron transport layer (240) and the perovskite light absorption layer (220).

[0094] The pavement layer (250) may include LiF, for example.

[0095] An electrode (270) can be formed on the first electron transport layer (240).

[0096] The electrode (270) serves to electrically connect the tandem solar cell to the outside and can be formed of a metallic material such as silver (Ag), gold (Au), copper (Cu), magnesium (Mg), molybdenum (Mo), and titanium (Ti), for example.

[0097] Meanwhile, as an optional embodiment, the electrode (270) may be formed in a grid pattern so that sunlight can enter the cell.

[0098] As an optional embodiment, a transparent electrode (260) may be formed between the first electron transport layer (240) and the electrode (270).

[0099] The transparent electrode (260) may be formed on the electron transport layer (240) using a conductive material that is transparent, and may include, for example, a transparent conductive oxide, a carbonaceous conductive material, and a metallic material. Examples of transparent conductive oxides may be used, such as ITO (Indium Tin Oxide), ICO (Indium Cerium Oxide), IWO (Indium Tungsten Oxide), ZITO (Zinc Indium Tin Oxide), ZIO (Zinc Indium Oxide), ZTO (Zinc Tin Oxide), GITO (Gallium Indium Tin Oxide), GIO (Gallium Indium Oxide), GZO (Gallium Zinc Oxide), AZO (Aluminum doped Zinc Oxide), FTO (Fluorine Tin Oxide), ZnO, etc. Carbonaceous conductive materials may include, for example, graphene or carbon nanotubes, and metallic materials may include, for example, metal nanowires or multilayer metal thin films such as Au / Ag / Cu / Mg / Mo / Ti. In this specification, the term "transparent" refers to the ability to transmit light to a certain degree or more, and is not necessarily interpreted to mean complete transparency. The materials described above are not necessarily limited to the embodiments described above and can be formed from various materials, and their structures can also be varied, such as being single-layer or multilayer.

[0100] Additionally, as an optional embodiment, an anti-reflection layer (280) may be further formed on the transparent electrode (260).

[0101] The anti-reflection layer (280) can prevent sunlight irradiated onto the perovskite upper cell (200) from being reflected, thereby improving the transmittance of sunlight and increasing the efficiency of the perovskite upper cell (200).

[0102] For example, the anti-reflection layer (280) may include a fluorine (F) material with high light transmittance and a very low refractive index, and may include LiF as an optional embodiment.

[0103] Next, the connection layer (10) is described.

[0104] The connecting layer (10) is a layer that connects the silicon lower cell (100) and the perovskite upper cell (200), and serves to physically combine and electrically connect the silicon lower cell (100) and the perovskite upper cell (200), and can perform charge recombination between the upper cell and the lower cell.

[0105] The connecting layer (10) can be used without limitation as long as it is a material of a connecting layer that is commonly used in the industry, and may include, for example, one or more selected from the group consisting of transparent conductive oxides, carbonaceous conductive materials, metallic materials and conductive polymers, and as specific examples, may include one or more TCO-based materials and / or nc-Si:H material layers selected from the group consisting of ITO (Indium Tin Oxide), ICO (Indium Cerium Oxide), IWO (Indium Tungsten Oxide), ZITO (Zinc Indium Tin Oxide), ZIO (Zinc Indium Oxide), ZTO (Zinc Tin Oxide), GITO (Gallium Indium Tin Oxide), GIO (Gallium Indium Oxide), GZO (Gallium Zinc Oxide), AZO (Aluminum doped Zinc Oxide), FTO (Fluorine Tin Oxide) and ZnO.

[0106] Figure 3 is a cross-sectional view schematically illustrating another example of the tandem solar cell of Figure 2.

[0107] Referring to FIG. 3, the perovskite tandem solar cell (2000) may include a silicon bottom cell (300), a perovskite top cell (400), and a connecting layer (20) connecting the silicon bottom cell (300) and the perovskite top cell (400).

[0108] First, the silicon lower cell (300) will be described.

[0109] The silicon bottom cell (300) may be a silicon solar cell having a bandgap of approximately 1.0 eV to 1.2 eV and may further include a silicon layer (310) and an emitter layer (315) disposed on the silicon layer (310).

[0110] The silicon layer (310) may have one of the structures of a known silicon solar cell and is not limited to a specific structure. For example, the silicon layer (310) may include a crystalline silicon substrate (not shown), a p-type amorphous or crystalline silicon layer (not shown), an n-type amorphous or crystalline silicon layer (not shown), and an amorphous intrinsic silicon layer (not shown), and may further include additional layers as needed, although not shown in the drawings.

[0111] Meanwhile, at least a portion of the lower and upper surfaces of the silicon lower cell (300) may be textured with pyramid-shaped irregularities to improve light efficiency. That is, an irregular surface is formed in the direction of incident light, and by increasing the path of light incident on the silicon layer (310) through the light scattering effect of the light incident through the irregular surface, the light collection is improved, thereby increasing the absorption rate of sunlight and enabling the achievement of a high current value. At this time, the pyramid angle of the surface of the texturing may exceed 5°, and preferably, the pyramid angle of the surface may exceed 30°.

[0112] Meanwhile, at least a portion of the upper surface of the silicon lower cell (300) is textured with pyramid-shaped irregularities, so that the shape of the intermediate layer (20) and the perovskite upper cell (400) formed on the silicon lower cell (300) can also be formed with the same shape as the pyramid irregularities on the upper surface of the silicon lower cell (300).

[0113] Next, the perovskite upper cell (400) is described.

[0114] The perovskite upper cell (400) is a cell connected to the silicon lower cell (300) described above, and may have a band gap of less than 1.66 eV, and may include a hole transport layer, a perovskite light absorption layer (420), a perovskite light absorption layer (420), a first electron transport layer (440), and an electrode (470), and the hole transport layer may include a first hole transport layer (410) and a second hole transport layer (430) disposed on the first hole transport layer (410).

[0115] As an optional embodiment, the perovskite upper cell (400) may further include a passivation layer (450) between the perovskite light absorption layer (420) and the first electron transport layer (440), and may further include a second electron transport layer (445) disposed on the first electron transport layer (440).

[0116] Additionally, as an optional embodiment, a transparent electrode (460) may be further included between the first electron transport layer (440) and the electrode (470), and an anti-reflection layer (470) disposed on the transparent electrode (460) may be further included.

[0117] Meanwhile, the specific details of the first hole transport layer (410), second hole transport layer (420), perovskite light absorption layer (430), passivation layer (450), first electron transport layer (440), second electron transport layer (445), transparent electrode (460), anti-reflection layer (480), and electrode (470) of the perovskite upper cell (400) are the same as those of the perovskite upper cell (200) of FIG. 1 described above, so they are omitted.

[0118] Next, the connection layer (20) is described.

[0119] The connecting layer (20) is a layer that connects the silicon lower cell (300) and the perovskite upper cell (400), and serves to physically combine and electrically connect the silicon lower cell (300) and the perovskite upper cell (400), and can perform charge recombination between the upper cell and the lower cell.

[0120] The connecting layer (20) can be used without limitation as long as it is a material of a connecting layer that is commonly used in the industry, and may include, for example, one or more selected from the group consisting of transparent conductive oxides, carbonaceous conductive materials, metallic materials and conductive polymers, and specific examples may be one or more TCO-based materials and / or nc-Si:H material layers selected from the group consisting of ITO (Indium Tin Oxide), ICO (Indium Cerium Oxide), IWO (Indium Tungsten Oxide), ZITO (Zinc Indium Tin Oxide), ZIO (Zinc Indium Oxide), ZTO (Zinc Tin Oxide), GITO (Gallium Indium Tin Oxide), GIO (Gallium Indium Oxide), GZO (Gallium Zinc Oxide), AZO (Aluminum doped Zinc Oxide), FTO (Fluorine Tin Oxide), and ZnO.

[0121] As a result, in a tandem solar cell according to an embodiment of the present invention, a SAM (Self-assembled monolayers) material and nanoparticles are mixed as a second hole transport layer, so that a perovskite thin film can be easily formed on the hydrophobic second hole transport layer, and at the same time, the performance of the solar cell device can be improved.

[0122]

[0123] <Preparation Example 1>

[0124] 100 ml of nano-sized SiOx particles ranging in size from 5 nm to 30 nm are prepared in an ethanol solvent at a ratio of 1 mg / ml, and then dispersed using an ultrasonic homogenizer for 5 minutes.

[0125] SAM organic material (Me-4PACz) is included in a solvent in which nanoparticles are dispersed to prepare a solution at a concentration of 2 mM.

[0126]

[0127] <Preparation Example 2>

[0128] Prepared in the same manner as Preparation Example 1, but with nano-particle SiOx particles prepared at an ethanol solvent ratio of 2 mg / ml.

[0129]

[0130] <Preparation Example 3>

[0131] Prepared in the same manner as Preparation Example 1, but with nano-sized SiOx particles prepared at a ratio of 3 mg / ml of ethanol solvent.

[0132] <Preparation Example 4>

[0133] SAM organic material (Me-4PACz) is prepared in ethanol at a concentration of 2 mM.

[0134]

[0135] <Preparation Example 5>

[0136] 100 ml of nano-sized SiOx particles ranging in size from 5 nm to 30 nm are prepared in an ethanol solvent at a ratio of 0.5 mg / ml, and then dispersed using an ultrasonic homogenizer for 5 minutes.

[0137]

[0138] <Example 1>

[0139] As the first electrode, a 20 nm ITO conductive thin film was deposited on an M4-sized silicon solar cell substrate via physical vapor deposition, and then a 20 nm NiOx hole transport layer was formed on an ITO conductive transparent substrate using a physical vapor deposition process. Subsequently, the solvent prepared in Preparation Example 1 was applied onto the NiOx via a spray process and heat-treated at 100°C. Afterward, Cs 0.2 FA 0.8 Pb(I 0.8 Br 0.2 A 1.3M perovskite precursor solution of composition )3 was applied using a blade process, 99% nitrogen was blown in, and then heat-treated at 150°C for 10 minutes to form a light-absorbing layer with a final thickness of 700 nm. A 13 nm thick C60 layer was formed. On the formed electron transport layer, a 10 nm SnO2 layer that serves both ETL and butter functions was deposited using an ALD process, followed by the formation of a 70 nm top TCO layer via physical vapor deposition, and finally, a second electrode with a screen-printable silver past was formed to fabricate a perovskite / silicon tandem photoelectric conversion device.

[0140]

[0141] <Example 2>

[0142] Prepared in the same manner as in Example 1, but the solvent prepared in Preparation Example 2 is applied onto NiOx by a spray process and heat-treated at 100°C.

[0143]

[0144] <Example 3>

[0145] Prepared in the same manner as in Example 1, but the solvent prepared in Preparation Example 3 is applied onto NiOx by a spray process and heat-treated at 100°C.

[0146]

[0147] <Comparative Example 1>

[0148] Prepared in the same manner as in Example 1, but first, the organic material prepared in Preparation Example 4 is applied onto NiOx, then a solvent containing the nanoparticles of Preparation Example 5 is applied onto the organic material layer by a spray process, and heat-treated at 100°C.

[0149]

[0150] VoC[V]Jsc[mA / cm 2 ]FF[%]Eff[%]Rs[Ω*cm 2 ]Rsh[Ω*cm 2 Example 11.78618.6975.3325.149.8839855 Example 21.79618.7577.4126.068.9128545 Example 31.76218.7476.2525.189.1434701 Comparative Example 11.67018.6578.9924.617.371006372

[0151] Table 1 shows the efficiency of tandem solar cells produced by the manufacturing methods of Examples 1 to 3 and Comparative Example 1. Examples 1 to 3, in which self-assembled organic materials and nanoparticles are formed as a single layer, have open-circuit voltages (VoC) of 1.786 V, 1.796 V, and 1.762 V, respectively, which can be seen to be superior to 1.670 V of Comparative Example 1.

[0152] Figure 4 is a graph showing the Fermi level of the second hole transport layer.

[0153] Referring to FIG. 4, the graph shows the Fermi level of the hole transport layer of a tandem solar cell containing only Me--4PACz, Example 1, and Comparative Example 1.

[0154] In the case of Comparative Example 1, where self-assembled organic material and nano material are formed as separate layers, it can be confirmed that there is not one Fermi level, and since Fermi level equilibrium does not occur, it can be inferred that there is a field influence due to the fixed charge of the nanoparticles.

[0155] On the other hand, in the case of Example 1, in which self-assembled organic material and nano material are formed as a single layer, it can be confirmed that there is one Fermi level, and since Fermi level equilibrium occurs, the field influence caused by the fixed charge of the nanoparticle is reduced, and it can be seen that the performance of the tandem solar cell is improved.

[0156] Consequently, the second hole transport layer according to the embodiment of the present invention allows nanoparticles to be uniformly distributed in the self-assembled material, thereby forming a single layer between the self-assembled material and the nanoparticles, which overcomes the problem of reduced solar cell device performance due to fixed charge, and enables the easy formation of a perovskite light absorption layer using a hydrophilic perovskite precursor solution on a hydrophobic self-assembled single layer.

[0157] As such, the present invention has been described with reference to the embodiments illustrated in the drawings, but this is merely illustrative, and those skilled in the art will understand that various modifications and equivalent alternative embodiments are possible therefrom. Accordingly, the true technical scope of protection of the present invention should be determined by the technical spirit of the appended claims.

[0158] The specific implementations described in the embodiments are examples and do not limit the scope of the embodiments in any way. For the sake of brevity of the specification, descriptions of conventional electronic configurations, control provision methods, software, and other functional aspects of said provision methods may be omitted. Additionally, the connections of lines or connecting members between components shown in the drawings are illustrative of functional connections and / or physical or circuit connections, and may be replaced or additionally represented as various functional connections, physical connections, or circuit connections in actual devices. Furthermore, unless specifically stated as "essential," "importantly," etc., a component may not be absolutely necessary for the application of the present invention.

[0159] In the specification of the embodiments (particularly in the claims), the use of the term "the above" and similar descriptive terms may be in both singular and plural. Furthermore, where a range is described in the embodiments, it is considered to include the invention with respect to individual values ​​within said range (unless otherwise stated), and is equivalent to describing each individual value constituting said range in the detailed description. Finally, regarding the steps constituting the method according to the embodiments, unless explicitly stated in order or otherwise stated, said steps may be performed in a suitable order. The embodiments are not necessarily limited by the order in which said steps are described. The use of any examples or exemplary terms (e.g., etc.) in the embodiments is merely for the purpose of describing the embodiments in detail, and the scope of the embodiments is not limited by said examples or exemplary terms unless limited by the claims. Furthermore, those skilled in the art will understand that various modifications, combinations, and changes may be made according to design conditions and factors within the scope of the claims or equivalents.

Claims

1. Substrate; A first electrode disposed on the above substrate; A second electrode positioned opposite to the first electrode; A light-absorbing layer disposed between the first electrode and the second electrode; and A hole transport layer is included between the second electrode and the light absorption layer, A perovskite solar cell in which the hole transport layer comprises a self-assembled organic material.

2. In Paragraph 1, The above hole transport layer includes a first hole transport layer and a second hole transport layer, and The second hole transport layer is disposed between the first hole transport layer and the light absorption layer, and The first hole transport layer above comprises a metal oxide or a metal, and A perovskite solar cell in which the second hole transport layer comprises a self-assembled organic material.

3. In Paragraph 2, A perovskite solar cell in which the second hole transport layer further comprises nanoparticles.

4. In Paragraph 3, The above nanoparticles are perovskite solar cells containing inorganic materials.

5. In Paragraph 4, The above inorganic material comprises silica (SiO2) or aluminum oxide (Al2O3), perovskite solar cell.

6. In Paragraph 3, A perovskite solar cell in which the second hole transport layer comprises a single layer in which the self-assembled organic material and the nanoparticle are mixed.

7. In Paragraph 1, The above self-assembled organic material is a perovskite solar cell comprising phosphonic acid or carbazole.

8. In Paragraph 7, The above self-assembled organic material comprises one or more selected from 2PACz, MeO-2PACz, Me-4PACz, Me-2PACz Br-2PACz, 4PADCB, and 3PATAT-C3, forming a perovskite solar cell.

9. Lower cell; A perovskite upper cell disposed on the lower cell above; and It includes a connecting layer disposed between the lower cell and the perovskite upper cell, and The above perovskite upper cell includes a perovskite light-dampening layer and a hole transport layer, and A tandem solar cell in which the hole transport layer comprises a self-assembled organic material.

10. In Paragraph 9, The above hole transport layer includes a first hole transport layer and a second hole transport layer, and The second hole transport layer is disposed between the first hole transport layer and the perovskite light absorption layer, and The first hole transport layer above comprises a metal oxide or a metal, and A tandem solar cell in which the second hole transport layer comprises a self-assembled organic material.

11. In Paragraph 10, A tandem solar cell in which the second hole transport layer further comprises nanoparticles.

12. In Paragraph 11, The above nanoparticles are tandem solar cells containing inorganic materials.

13. In Paragraph 12, The above inorganic material comprises silica (SiO2) or aluminum oxide (Al2O3), perovskite solar cell.

14. In Paragraph 11, A tandem solar cell in which the second hole transport layer comprises a single layer in which the self-assembled organic material and the nanoparticle are mixed.

15. In Paragraph 9, The above self-assembled organic material is a tandem solar cell comprising phosphonic acid or carbazole.

16. In Paragraph 15, The above self-assembled organic material comprises one or more selected from 2PACz, MeO-2PACz, Me-4PACz, Me-2PACz Br-2PACz, 4PADCB, and 3PATAT-C3, forming a tandem solar cell.

17. In Paragraph 9, The above perovskite upper cell is, An electrode positioned to face the above-mentioned perovskite light-absorbing layer; and A tandem solar cell comprising an electron transport layer disposed between the perovskite light absorption layer and the electrode.

Images