Perovskite solar cell and tandem solar cell comprising same

Abstract

An embodiment of the present invention provides a perovskite solar cell comprising: a substrate; a first electrode disposed on the substrate; a second electrode disposed to be opposite the first electrode; a light-absorbing layer containing a perovskite-based material and disposed between the first electrode and the second electrode; and a first electron transport layer disposed between the light-absorbing layer and the second electrode, wherein the first electron transport layer contains a plurality of metal oxide layers.

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] Globally, in order to reduce dependence on fossil fuels, research and development on alternative and clean energy—new energy sources that do not have an adverse effect on the environment and are not subject to depletion—are actively underway. Among these, solar cells are semiconductor devices that directly convert light energy into electrical energy and consist of two or more layers of semiconductor materials that absorb light. When light is irradiated onto a semiconductor diode forming a pn junction in the solar cell, photons are absorbed to generate electron / hole pairs, and a potential difference is generated at the junction of the two different materials, causing an electric current to flow.

[0003] Meanwhile, perovskite solar cells are considered a key next-generation technology, and these perovskite solar cells include a light-absorbing layer containing a perovskite compound and may additionally include one or more charge-transporting layers, such as an electron transport layer.

[0004] Perovskite compounds are relatively sensitive to heat, making it difficult to carry out high-temperature processes, and there are limitations in realizing, for example, perovskite solar cells containing an electron transport layer with desired characteristics.

[0005] Embodiments of the present invention can provide a perovskite solar cell capable of improving the open-circuit voltage (Voc) and fill factor (FF) values ​​of a solar cell by forming an improved electron transport layer, and a tandem solar cell including the same.

[0006] 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 containing a perovskite-based material disposed between the first electrode and the second electrode, and a first electron transport layer disposed between the light absorption layer and the second electrode, wherein the first electron transport layer comprises a plurality of metal oxide layers.

[0007] Another embodiment of the present invention for achieving the above-described purpose discloses a tandem solar cell comprising a silicon semiconductor layer, a first electrode on the silicon semiconductor layer, a second electrode disposed opposite to the first electrode, a light absorption layer containing a perovskite-based material disposed between the first electrode and the second electrode, a first electron transport layer disposed between the light absorption layer and the second electrode, and a metal electrode on the second electrode, wherein the first electron transport layer comprises a plurality of metal oxide layers.

[0008] The perovskite solar cell according to an embodiment of the present invention and the tandem solar cell including the same can improve the open-circuit voltage (Voc) and fill factor (FF) values ​​of the solar cell.

[0009] FIG. 1 is a cross-sectional view schematically illustrating an example of a perovskite solar cell according to one embodiment of the present invention.

[0010] Figure 2 is an enlarged view of E in Figure 1.

[0011] Figure 3 is a schematic diagram illustrating another example of the perovskite solar cell of Figure 1.

[0012] FIG. 4 is a cross-sectional view schematically illustrating an example of a tandem solar cell including a perovskite solar cell according to one embodiment of the present invention.

[0013] Figure 5 is an enlarged view of T in Figure 4.

[0014] 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 containing a perovskite-based material disposed between the first electrode and the second electrode, and a first electron transport layer disposed between the light absorption layer and the second electrode, wherein the first electron transport layer comprises a plurality of metal oxide layers.

[0015] The first electron transport layer comprises a first metal oxide layer, a second metal oxide layer, and a third metal oxide layer, and each of the first to third metal oxide layers may comprise one or more selected from SnOx, TiOx, ZnOx, WOx, NbOx, InOx, AlOx, HfOx, BaSnOx, ZrOx, VOx, and CeOx.

[0016] The first metal oxide layer may include SnOx, the second metal oxide layer may include TiOx, and the third metal oxide layer may include SnOx.

[0017] The sum of the thicknesses of the first metal oxide layer and the third metal oxide layer may be thicker than the thickness of the second metal oxide layer.

[0018] A second electron transport layer may be further included between the first electron transport layer and the perovskite light absorption layer.

[0019] The second electron transport layer may include a fullerene-based material.

[0020] The thickness of the second electron transport layer may be 5 nm to 30 nm.

[0021] A passivation layer may be further included between the second electron transport layer and the perovskite light absorption layer.

[0022] The above passivation layer may include LiF.

[0023] Another embodiment of the present invention for achieving the above-described purpose discloses a tandem solar cell comprising a silicon semiconductor layer, a first electrode on the silicon semiconductor layer, a second electrode disposed opposite to the first electrode, a light absorption layer containing a perovskite-based material disposed between the first electrode and the second electrode, a first electron transport layer disposed between the light absorption layer and the second electrode, and a metal electrode on the second electrode, wherein the first electron transport layer comprises a plurality of metal oxide layers.

[0024] The first electron transport layer comprises a first metal oxide layer, a second metal oxide layer, and a third metal oxide layer, and each of the first to third metal oxide layers may comprise one or more selected from SnOx, TiOx, ZnOx, WOx, NbOx, InOx, AlOx, HfOx, BaSnOx, ZrOx, VOx, and CeOx.

[0025] The first metal oxide layer may include SnOx, the second metal oxide layer may include TiOx, and the third metal oxide layer may include SnOx.

[0026] The sum of the thicknesses of the first metal oxide layer and the third metal oxide layer may be thicker than the thickness of the second metal oxide layer.

[0027] A second electron transport layer may be further included between the first electron transport layer and the perovskite light absorption layer.

[0028] The second electron transport layer may include a fullerene-based material.

[0029] The thickness of the second electron transport layer may be 5 nm to 30 nm.

[0030] A passivation layer may be further included between the second electron transport layer and the perovskite light absorption layer.

[0031] The above passivation layer may include LiF.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] In the following examples, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] One embodiment of the present invention relates to a perovskite solar cell, and another embodiment of the present invention relates to a tandem solar cell comprising a perovskite solar cell. Various examples of a perovskite solar cell and a tandem solar cell comprising a perovskite solar cell are schematically illustrated in FIGS. 1 to 5.

[0041] FIG. 1 is a schematic cross-sectional view illustrating an example of a perovskite solar cell according to one embodiment of the present invention, and FIG. 2 is an enlarged view of E in FIG. 1.

[0042] Referring to FIGS. 1 and 2, a perovskite solar cell (1) may include a substrate (10), a first electrode (20), an electron transport layer (60), a light absorption layer (40), and a second electrode (90).

[0043] Additionally, the perovskite solar cell (1) may further include one or more layers as an optional embodiment, for example, may include a hole transport layer (30) between the first electrode (20) and the light absorption layer (40), and may include a passivation layer (50) between the light absorption layer (40) and the electron transport layer (60). Also, as an example, a transparent electrode (70) may be included between the electron transport layer (60) and the second electrode (90).

[0044] Additionally, as an optional embodiment, one or more anti-reflective films (80) on the transparent electrode (70) may be further included.

[0045] 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.

[0046] However, the structure of the perovskite solar cell illustrated in FIG. 1 is one embodiment and is not limited thereto, and the configuration of the electron transport layer including the metal oxide multilayer thin film 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.

[0047] A substrate (10) 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.

[0048] The first electrode (20) can be formed on the substrate (10) and can be formed of a conductive material having light transparency.

[0049] For example, the first electrode (20) may include 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 (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.

[0050] The hole transport layer (30) may be a layer formed on the first electrode (20) to which holes formed in the perovskite light absorption layer (40) described later are transported. For example, the hole transport layer (30) 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.

[0051] Meanwhile, the hole transport layer (30) 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.

[0052] A light absorption layer (40) containing a perovskite-based material can be formed on a 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 formed in the perovskite light absorption layer (40) are transferred to the electron transport layer (60) described later, and holes formed in the perovskite light absorption layer (40) can be transferred to the hole transport layer (30).

[0053] For example, the perovskite light-absorbing layer (40) 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).

[0054] As a specific example, the perovskite light-absorbing layer (40) 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 (40) 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).

[0055] The pavement layer (50) can be formed on the perovskite light absorption layer (40), and, for example, the metal oxide forming the electron transport layer (60) described later can serve to prevent the perovskite compound constituting the light absorption layer from being oxidized.

[0056] As an optional embodiment, the pavement layer (50) may include LiF.

[0057] The electron transport layer (60) may be formed on the perovskite light absorption layer (40), and the electron transport layer (60) may include, for example, a first electron transport layer (61) and a second electron transport layer (62).

[0058] The first electron transport layer (61) may include at least a plurality of metal oxide layers. Alternatively, the first electron transport layer (61) may include a metal oxide multilayer.

[0059] The second electron transport layer (62) may contain a material of the florene series.

[0060] The first electron transport layer (61) comprises a plurality of layers, and each of the plurality of layers may contain a metal oxide. For example, each of the plurality of layers of the first electron transport layer (61) may contain at least two different metal oxides.

[0061] As an optional embodiment, the first electron transport layer (61) may include three or more layers, for example, a first metal oxide layer (A), a second metal oxide layer (B), and a third metal oxide layer (C).

[0062] The first metal oxide layer (A) may include one or more selected from, for example, SnOx, TiOx, ZnOx, WOx, NbOx, InOx, AlOx, HfOx, BaSnOx, ZrOx, VOx, and CeOx, and specifically, SnOx may be included. 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.

[0063] The second metal oxide layer (B) may include one or more selected from, for example, SnOx, TiOx, ZnOx, WOx, NbOx, InOx, AlOx, HfOx, BaSnOx, ZrOx, VOx, and CeOx, and specifically, may include TiOx. In addition, the second metal oxide layer (B) can 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.

[0064] The third metal oxide layer (C) may include one or more selected from, for example, SnOx, TiOx, ZnOx, WOx, NbOx, InOx, AlOx, HfOx, BaSnOx, ZrOx, VOx, and CeOx, and specifically, SnOx may be included. In addition, the third metal oxide layer (C) can 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.

[0065] Meanwhile, titanium oxide (TiOx) and aluminum oxide (AlOx) can form dense ultrathin films at low temperatures, similar to tin oxide (SnOx), and when a multilayer structure with tin oxide (SnOx) is implemented, the similarity of the band gaps can reduce band gap mismatching, thereby enabling smooth electron transport. In addition, compared to having a high defect density in the thin film when formed as a single layer of tin oxide (SnOx), when a multilayer structure is formed with tin oxide (SnOx) and titanium oxide (TiOx) or aluminum oxide (AlOx), the high defect density of the thin film can be compensated for, thereby reducing non-radiative charge recombination at the interface and increasing the Voc (voltage) and FF (fill factor) of the device.

[0066] In addition, titanium oxide (TiOx) and aluminum oxide (AlOx) can form dense ultrathin films at low temperatures, enabling low-temperature atomic layer deposition. This allows for the rapid formation of multilayer thin films under the same low-temperature conditions by simply varying the source without any special variations, which can be advantageous for mass production processes.

[0067] Meanwhile, the thickness of the first electron transport layer (61) can be formed to be 3 nm to 20 nm. At this time, if it is formed to a thickness thinner than 3 nm, the hole blocking characteristics may be reduced, and if it is formed to a thickness thicker than 20 nm, the electron transport characteristics may be reduced, so the performance of the perovskite solar cell (1) device may be reduced.

[0068] As an optional embodiment, the first electron transport layer (61) may have a first metal oxide layer (A) formed of tin oxide (SnOx), a second metal oxide layer (B) formed of titanium oxide (TiOx), and a third metal oxide layer (C) formed of tin oxide (SnOx).

[0069] At this time, the ratio of the thicknesses of tin oxide (SnOx) and titanium oxide (TiOx) included in the first electron transport layer (61) is not specifically limited, but the thickness of tin oxide (SnOx) may be greater than the thickness of titanium oxide (TiOx). This is because if the thickness of titanium oxide (TiOx) is formed to be greater than the thickness of tin oxide (SnOx), the electron transport characteristics of the first electron transport layer (61) may be reduced due to the characteristics of titanium oxide (TiOx), which has lower electron mobility and lower electron extraction performance compared to tin oxide (SnOx).

[0070] Meanwhile, the first metal oxide layer (A) of the first electron transport layer (61) is a layer that comes into contact with the second electron transport layer (62), which contains a hydrophobic fullerene-based material, and must be able to exhibit excellent adhesion characteristics with the second electron transport layer (62) and allow the thin film process to be carried out at a relatively low temperature. Accordingly, it is preferable that the first metal oxide layer (A) be formed by including tin oxide (SnOx), and since the first metal oxide layer (A) is formed of tin oxide (SnOx), it can exhibit excellent adhesion characteristics with the second electron transport layer (62) and allow the thin film process to be carried out at a relatively low temperature, thereby preventing the second electron transport layer (62), which is formed of a heat-sensitive fullerene-based material, from being damaged by heat, and furthermore, it can prevent the light absorption layer formed of a heat-sensitive perovskite compound from being damaged by heat and the performance of the solar cell device from decreasing.

[0071] Meanwhile, the fullerene layer formed by thermal evaporation on the perovskite light-absorbing layer (40) lacks the characteristic of blocking the transport of holes, so it may be necessary to additionally form a layer having electron transport and hole blocking characteristics. However, since the surface of the fullerene thin film has hydrophobic characteristics, it is very difficult to form an additional layer on it, and even if it is formed, there may be a problem in that it is difficult to control defects that cause electrical resistance due to the low adhesion characteristics of the interface. In this embodiment, the first electron transport layer (61) is formed on the second electron transport layer (62) to improve the manufacturing characteristics of the electron transport layer (60) and improve the electrical characteristics of the electron transport layer (60). In addition, as an optional embodiment, when forming the electron transport layer (60), the first electron transport layer (61) can be formed using a low-temperature process, specifically an atomic deposition process (ALD), to improve the electrical characteristics and stability of the photoactive layer (40), thereby improving the open-circuit voltage (Voc) and fill factor (FF) of the solar cell.

[0072] Meanwhile, the thickness of the second electron transport layer (62) formed from a fullerene-based material can be formed to be 5 nm to 30 nm. At this time, 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, so the performance of the perovskite solar cell (1) device may be reduced.

[0073]

[0074] Electron transport layer thickness ratio (aSnOx:bTiOx:cSnOx)Voc(V)Jsc(mA / cm²) 2 )FF(%)Rs(Ω) Comparative Example 1 Single layer (SnOx) a=1, b=0, c=0 1.70 7 18.6 7 6 7.78 19.41 Example 1 Multilayer (SnOx / TiOx / SnOx) a=0.4, b=0.2, c=0.4 1.77 3 18.6 5 7 7.4 9 9.01 Example 2 Multilayer (SnOx / TiOx / SnOx) a=0.6, b=0.2, c=0.2 1.76 4 18.6 3 7 4.9 10.21

[0075] Table 1 shows the parameters of the solar cell elements of Example 1, Example 2, and Comparative Example 1 according to the thickness ratio of tin oxide (SnOx) and titanium oxide (TiOx) forming the multilayer of the first electron transport layer (61). Referring to Table 1, it can be seen that the open-circuit voltage (Voc) of Comparative Example 1, which forms a single layer of tin oxide (SnOx), is 1.707V and the fill factor (FF) is 67.78%.

[0076] In addition, it can be confirmed that Example 1, in which a multilayer including a first metal oxide layer (A), a second metal oxide layer (B), and a third metal oxide layer (C) is formed, has an open-circuit voltage (Voc) of 1.773V and a fill factor (FF) of 77.49%, so that the open-circuit voltage (Voc) and fill factor (FF) are improved compared to the case where the first electron transport layer (61) is formed with a single layer of tin oxide (SnOx).

[0077] In addition, in Example 2, in which a multilayer including a first metal oxide layer (A), a second metal oxide layer (B), and a third metal oxide layer (C) is formed, it can be confirmed that the open-circuit voltage (Voc) is 1.764V and the filling rate (FF) is 74.9%, so it can be confirmed that the open-circuit voltage (Voc) and the filling rate (FF) are improved compared to the case where the first electron transport layer (61) is formed with a single layer of tin oxide (SnOx).

[0078] That is, if the first electron transport layer (61) is formed as a SnOx / TiOx / SnOx multilayer rather than a tin oxide (SnOx) single layer, the open-circuit voltage (Voc) and fill factor (FF) of the solar cell device can be improved by reducing the defect density of the first electron transport layer (61).

[0079] The transparent electrode (70) can be formed on the electron transport layer (60) 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 (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.

[0080] The anti-reflection film (80) can be formed on the transparent electrode (70) and 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).

[0081] For example, the anti-reflection film (80) may include fluorine (F), which has a high light transmittance and a very low refractive index, and may include LiF as an optional embodiment.

[0082] The second electrode (90) can be formed on the transparent electrode (80) and can serve to electrically connect the perovskite solar cell (1) to the outside.

[0083] For example, the second electrode (90) can be formed of a metallic material such as silver (Ag), and a pattern of a certain shape can be formed so that sunlight can enter the cell.

[0084] Figure 3 is a cross-sectional view schematically illustrating another example of the perovskite solar cell of Figure 1.

[0085] Referring to FIG. 3, the above-described perovskite solar cell (1) may be textured at least some layers to improve light efficiency. By textured at least some layers of the perovskite solar cell, an uneven surface is formed in the direction of incident light, and the path of light incident to the perovskite light-absorbing layer (40) is increased through the light scattering effect of the light incident through the uneven surface, thereby improving light collection and increasing the absorption rate of sunlight.

[0086] Consequently, the perovskite solar cell according to the embodiment of the present invention can exhibit excellent adhesion characteristics with a hydrophobic second electron transport layer by forming the first electron transport layer as a metal oxide multilayer, and can perform a thin film process at a relatively low temperature, thereby preventing the reduction in performance of the perovskite solar cell device caused by damage to heat-sensitive fullerene-based materials and perovskite compounds by heat.

[0087] In addition, the power conversion efficiency of the device can be increased by improving the open-circuit voltage (Voc) and fill factor (FF) through the effect of reducing the defect density of the first electron transport layer.

[0088] FIG. 4 is a schematic cross-sectional view illustrating an example of a tandem solar cell including a perovskite solar cell according to an embodiment of the present invention, and FIG. 5 is an enlarged view of T in FIG. 4.

[0089] Referring to FIGS. 4 and 5, a tandem solar cell (2) including a perovskite solar cell (2000) may include a silicon semiconductor layer (100), a first electrode (200) formed on the silicon semiconductor layer (100), a perovskite light absorption layer (400), an electron transport layer (500) formed on the perovskite light absorption layer (400), and a second electrode (800).

[0090] Additionally, the perovskite solar cell (2000) may include one or more additional layers as an optional embodiment, for example, a hole transport layer (300) between the first electrode (200) and the light absorption layer (400). Also, as an example, a transparent electrode (600) may be included between the electron transport layer (500) and the second electrode (800).

[0091] Additionally, as an optional embodiment, one or more anti-reflective films (700) on the transparent electrode (600) may be further included.

[0092] Meanwhile, a tandem solar cell (2) including a perovskite solar cell may include a silicon solar cell (bottom cell) (1000) and a perovskite solar cell (top cell) (2000) formed on the silicon solar cell (1000), and a junction layer (not shown) that joins and electrically connects the two may be provided between the silicon solar cell (1000) and the perovskite solar cell (2000). This junction layer may be implemented using a transparent conductive oxide (TCO), a carbonaceous conductive material, a metallic material, or a conductive polymer so that long-wavelength light passing through the perovskite solar cell (2000) can be incident on the silicon solar cell (1000) placed below without transmission loss.

[0093] The silicon solar cell (1000) may be a silicon solar cell having a bandgap of approximately 1.0 eV to 1.2 eV. It may include a back electrode (not shown) made of a metal or metal alloy disposed on the substrate and a silicon semiconductor layer (100) disposed on the back electrode. At this time, the back electrode may include silver (Ag), titanium (Ti), gold (Au), etc.

[0094] The silicon semiconductor layer (100) may include a p-type silicon semiconductor layer and an n-type silicon semiconductor layer disposed on the p-type silicon semiconductor layer.

[0095] A perovskite solar cell (2000) may include a first electrode (200), a perovskite light absorption layer (400), an electron transport layer (500) formed on the perovskite light absorption layer (400), and a second electrode (800).

[0096] Additionally, the perovskite solar cell (2000) may include one or more additional layers as an optional embodiment, for example, a hole transport layer (300) between the first electrode (200) and the light absorption layer (400). Also, as an example, a transparent electrode (600) may be included between the electron transport layer (500) and the second electrode (800).

[0097] Additionally, as an optional embodiment, one or more anti-reflective films (700) on the transparent electrode (600) may be further included.

[0098] The first electrode (200) may be formed from a conductive material having light transparency, 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 (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.

[0099] The hole transport layer (300) may be a layer formed on a silicon solar cell (1000) to which holes formed in the perovskite light absorption layer (400) described later are transported. For example, the hole transport layer (300) 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 polymer 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.

[0100] Meanwhile, the hole transport layer (300) 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.

[0101] A light absorption layer (400) containing a perovskite-based material can be formed on a hole transport layer (300), 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 formed in the perovskite light absorption layer (400) are transferred to the electron transport layer (500) described later, and holes formed in the perovskite light absorption layer (400) can be transferred to the hole transport layer (300).

[0102] For example, the perovskite light-absorbing layer (400) 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).

[0103] 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-yPbI3, (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).

[0104] The electron transport layer (500) may be formed on the perovskite light absorption layer (400), and the electron transport layer (500) may include, for example, a first electron transport layer (510) formed of a multilayer of metal oxides and a second electron transport layer (520) formed of a fullene-based material.

[0105] The first electron transport layer (510) may include a structure in which different metal oxides each form a single layer and form a multilayer. At this time, the multilayer may include a first metal oxide layer (A), a second metal oxide layer (B), and a third metal oxide layer (C).

[0106] The first metal oxide layer (A) may include one or more selected from, for example, SnOx, TiOx, ZnOx, WOx, NbOx, InOx, AlOx, HfOx, BaSnOx, ZrOx, VOx, and CeOx, and specifically, SnOx may be included. 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.

[0107] The second metal oxide layer (B) may include one or more selected from, for example, SnOx, TiOx, ZnOx, WOx, NbOx, InOx, AlOx, HfOx, BaSnOx, ZrOx, VOx, and CeOx, and specifically, may include TiOx. In addition, the second metal oxide layer (B) can 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.

[0108] The third metal oxide layer (C) may include one or more selected from, for example, SnOx, TiOx, ZnOx, WOx, NbOx, InOx, AlOx, HfOx, BaSnOx, ZrOx, VOx, and CeOx, and specifically, SnOx may be included. In addition, the third metal oxide layer (C) can 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.

[0109] Meanwhile, titanium oxide (TiOx) and aluminum oxide (AlOx) can form dense ultrathin films at low temperatures, similar to tin oxide (SnOx), and when a multilayer structure with tin oxide (SnOx) is implemented, there is no bandgap mismatch, allowing for smooth electron transport. In addition, compared to having a high defect density in the film when formed as a single layer of tin oxide (SnOx), when a multilayer structure is formed with tin oxide (SnOx) and titanium oxide (TiOx) or aluminum oxide (AlOx), the high defect density of the film can be compensated for, thereby reducing non-radiative charge recombination at the interface and increasing the Voc (voltage) and FF (fill factor) of the device.

[0110] In addition, titanium oxide (TiOx) and aluminum oxide (AlOx) can form dense ultrathin films at low temperatures, enabling low-temperature atomic layer deposition. This allows for the rapid formation of multilayer thin films under the same low-temperature conditions by simply varying the source without any special variations, which can be advantageous for mass production processes.

[0111] Meanwhile, the thickness of the first electron transport layer (510) can be formed to be 3 nm to 20 nm. At this time, if it is formed to a thickness thinner than 3 nm, the hole blocking characteristics may be reduced, and if it is formed to a thickness thicker than 20 nm, the electron transport characteristics may be reduced, so the performance of the perovskite solar cell (1) device may be reduced.

[0112] As an optional embodiment, the first electron transport layer (510) may have a first metal oxide layer (A) formed of tin oxide (SnOx), a second metal oxide layer (B) formed of titanium oxide (TiOx), and a third metal oxide layer (C) formed of tin oxide (SnOx).

[0113] At this time, the ratio of the thicknesses of the tin oxide (SnOx) and titanium oxide (TiOx) forming the first electron transport layer (510) is not specifically limited, but the thickness of the tin oxide (SnOx) may be greater than the thickness of the titanium oxide (TiOx). This is because if the thickness of the titanium oxide (TiOx) is formed to be greater than the thickness of the tin oxide (SnOx), the electron transport characteristics of the first electron transport layer (510) may be reduced due to the characteristics of the titanium oxide (TiOx), which has lower electron mobility and lower electron extraction performance compared to the tin oxide (SnOx).

[0114] Meanwhile, the first metal oxide layer (A) of the first electron transport layer (510) is a layer that comes into contact with the second electron transport layer (520), which contains a hydrophobic fullerene-based material, and must be able to exhibit excellent adhesion characteristics with the second electron transport layer (520) and allow the thin film process to be carried out at a relatively low temperature. Accordingly, it is preferable that the first metal oxide layer (A) be formed by including tin oxide (SnOx), and by forming the first metal oxide layer (A) with tin oxide (SnOx), it can exhibit excellent adhesion characteristics with the second electron transport layer (520) and allow the thin film process to be carried out at a relatively low temperature, thereby preventing the second electron transport layer (520), which is formed with a heat-sensitive fullerene-based material, from being damaged by heat, and furthermore, it can prevent the light absorption layer formed with a heat-sensitive perovskite compound from being damaged by heat and the performance of the solar cell device from decreasing.

[0115] Meanwhile, the thickness of the second electron transport layer (520) formed from a fullerene-based material can be formed to be 5 nm to 30 nm. At this time, 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, so the performance of the perovskite solar cell (1) device may be reduced.

[0116] Electron transport layer thickness ratio (aSnOx:bTiOx:cSnOx)Voc(V)Jsc(mA / cm²) 2 )FF(%)Rs(Ω) Comparative Example 1 Single layer (SnOx) a=1, b=0, c=0 1.70 7 18.6 7 6 7.78 19.41 Example 1 Multilayer (SnOx / TiOx / SnOx) a=0.4, b=0.2, c=0.4 1.77 3 18.6 5 7 7.4 9 9.01 Example 2 Multilayer (SnOx / TiOx / SnOx) a=0.6, b=0.2, c=0.2 1.76 4 18.6 3 7 4.9 10.21

[0117] Table 2 shows the parameters of the solar cell elements of Example 1, Example 2 and Comparative Example 1 according to the thickness ratio of tin oxide (SnOx) and titanium oxide (TiOx) forming the multilayer of the first electron transport layer (61). Referring to Table 2, it can be seen that the open-circuit voltage (Voc) of Comparative Example 1, which forms a single layer of tin oxide (SnOx), is 1.707V and the fill factor (FF) is 67.78%.

[0118] In addition, it can be confirmed that Example 1, in which a multilayer including a first metal oxide layer (A), a second metal oxide layer (B), and a third metal oxide layer (C) is formed, has an open-circuit voltage (Voc) of 1.773V and a fill factor (FF) of 77.49%, so that the open-circuit voltage (Voc) and fill factor (FF) are improved compared to the case where the first electron transport layer (61) is formed with a single layer of tin oxide (SnOx).

[0119] In addition, in Example 2, in which a multilayer including a first metal oxide layer (A), a second metal oxide layer (B), and a third metal oxide layer (C) is formed, it can be confirmed that the open-circuit voltage (Voc) is 1.764V and the filling rate (FF) is 74.9%, so it can be confirmed that the open-circuit voltage (Voc) and the filling rate (FF) are improved compared to the case where the first electron transport layer (61) is formed with a single layer of tin oxide (SnOx).

[0120] That is, if the first electron transport layer (510) is formed as a SnOx / TiOx / SnOx multilayer rather than a tin oxide (SnOx) single layer, the open-circuit voltage (Voc) and fill factor (FF) of the solar cell device can be improved by reducing the defect density of the first electron transport layer (510).

[0121] As an optional embodiment, a pavement layer (not shown) may be formed between the perovskite light absorption layer (400) and the electron transport layer (500), and, for example, the pavement layer (not shown) may serve to prevent the metal oxide forming the electron transport layer (500) from oxidizing the perovskite compound constituting the light absorption layer (400).

[0122] As an optional embodiment, the pavement layer may include LiF.

[0123] The transparent electrode (600) may be formed on the electron transport layer (500) 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.

[0124] The anti-reflection film (700) can be formed on the transparent electrode (600) and can prevent sunlight irradiated onto the perovskite solar cell (2000) from being reflected, thereby improving the transmittance of sunlight and increasing the efficiency of the perovskite solar cell (1).

[0125] For example, the anti-reflection film (700) may include a fluorine (F) material with high light transmittance and a very low refractive index, and may include LiF as an optional embodiment.

[0126] The second electrode (800) can be formed on the transparent electrode (700) and can serve to electrically connect the perovskite solar cell (2000) to the outside.

[0127] For example, the second electrode (800) can be formed of a metallic material such as silver (Ag) and can be formed in a grid pattern so that sunlight can enter the cell.

[0128] As a result, the perovskite solar cell according to the embodiment of the present invention and the tandem solar cell including the same can exhibit excellent adhesion characteristics with the second electron transport layer having hydrophobicity by forming the first electron transport layer as a metal oxide multilayer, and can perform a thin film process at a relatively low temperature, thereby preventing the performance of the perovskite solar cell device from being reduced due to damage caused by heat to fullerene-based materials and perovskite compounds that are sensitive to heat.

[0129] 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.

[0130] 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.

[0131] 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 containing a perovskite-based material disposed between the first electrode and the second electrode; and It includes a first electron transport layer disposed between the light absorption layer and the second electrode, and The first electron transport layer comprises a plurality of metal oxide layers, in a perovskite solar cell.

2. In Paragraph 1, A perovskite solar cell wherein the first electron transport layer comprises a first metal oxide layer, a second metal oxide layer, and a third metal oxide layer, and the first to third metal oxide layers each comprise one or more selected from SnOx, TiOx, ZnOx, WOx, NbOx, InOx, AlOx, HfOx, BaSnOx, ZrOx, VOx, and CeOx.

3. In Paragraph 2, A perovskite solar cell in which the first metal oxide layer comprises SnOx, the second metal oxide layer comprises TiOx, and the third metal oxide layer comprises SnOx.

4. In Paragraph 3, A perovskite solar cell in which the sum of the thicknesses of the first metal oxide layer and the third metal oxide layer is thicker than the thickness of the second metal oxide layer.

5. In Paragraph 1, A perovskite solar cell further comprising a second electron transport layer between the first electron transport layer and the perovskite light absorption layer.

6. In Paragraph 5, A perovskite solar cell in which the second electron transport layer comprises a fullerene-based material.

7. In Paragraph 5, A perovskite solar cell having a second electron transport layer with a thickness of 5 nm to 30 nm.

8. In Paragraph 5, A perovskite solar cell further comprising a passivation layer between the second electron transport layer and the perovskite light absorption layer.

9. In Paragraph 8, The above passivation layer is a perovskite solar cell containing LiF.

10. In Paragraph 1, A perovskite solar cell having a first electron transport layer with a thickness of 3 nm to 20 nm.

11. Silicon semiconductor layer; A first electrode on the silicon semiconductor layer above; A second electrode positioned opposite to the first electrode; A light absorption layer containing a perovskite-based material disposed between the first electrode and the second electrode; A first electron transport layer disposed between the light absorption layer and the second electrode; and It includes a metal electrode on the second electrode, and The above first electron transport layer comprises a plurality of metal oxide layers, forming a tandem solar cell.

12. In Paragraph 11, A tandem solar cell, wherein the first electron transport layer comprises a first metal oxide layer, a second metal oxide layer, and a third metal oxide layer, and the first to third metal oxide layers each comprise one or more selected from SnOx, TiOx, ZnOx, WOx, NbOx, InOx, AlOx, HfOx, BaSnOx, ZrOx, VOx, and CeOx.

13. In Paragraph 11, A tandem solar cell comprising a first metal oxide layer comprising SnOx, a second metal oxide layer comprising TiOx, and a third metal oxide layer comprising SnOx.

14. In Paragraph 13, A tandem solar cell in which the sum of the thicknesses of the first metal oxide layer and the third metal oxide layer is thicker than the thickness of the second metal oxide layer.

15. In Paragraph 11, A tandem solar cell further comprising a second electron transport layer between the first electron transport layer and the perovskite light absorption layer.

16. In Paragraph 15, A tandem solar cell in which the second electron transport layer comprises a fullerene-based material.

17. In Paragraph 15, A tandem solar cell having a second electron transport layer with a thickness of 5 nm to 30 nm.

18. In Paragraph 15, A tandem solar cell further comprising a passivation layer between the second electron transport layer and the perovskite light absorption layer.

19. In Paragraph 18, The above passivation layer comprises LiF, a tandem solar cell.

20. In Paragraph 1, A tandem solar cell having a first electron transport layer with a thickness of 3 nm to 20 nm.

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