Perovskite solar cell and tandem solar cell comprising same

Abstract

One 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 photoactive layer disposed between the first electrode and the second electrode and containing a perovskite-based material; and a composite layer disposed between the photoactive layer and the second electrode, containing a passivation material and an electron transport material, and formed to have regions in which ratios of the passivation material and the transport material differ along a thickness direction, wherein the mechanical strength of the perovskite solar cell can be increased and the power conversion efficiency thereof can be improved.

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 photoactive layer containing a perovskite compound and may additionally include one or more charge transfer layers, such as an electron transport layer.

[0004] Among currently mass-producible technologies, fullerene thin films formed by thermal evaporation on perovskite photoactive layers are attracting attention as electron transport layers. However, fullerene layers have several limitations due to the inherent properties of the material itself. In particular, the spherical molecular structure results in a low film density, and the hydrophobic nature weakens the mechanical strength of the interface, which can lead to reduced device stability. Furthermore, the fullerene layer, which has a high work function, can obstruct electron transport and cause charge recombination by being located between the photoactive layer and the electrode, thereby degrading device performance.

[0005] The perovskite solar cell according to the embodiments of the present invention and the tandem solar cell including the same can have improved power conversion efficiency.

[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 photoactive layer containing a perovskite-based material disposed between the first electrode and the second electrode; and a composite layer disposed between the photoactive layer and the second electrode, containing a passivation material and an electron transfer material, and formed such that the ratio of the passivation material and the transfer material differs in a region with respect to the thickness direction.

[0007] Another embodiment of the present invention for achieving the above-described purpose discloses a tandem solar cell comprising a silicon layer, a recombination layer on the silicon layer, an electrode disposed opposite to the recombination layer, a photoactive layer containing a perovskite-based material disposed between the recombination layer and the electrode, and a composite layer disposed between the photoactive layer and the second electrode and containing a passivation material and an electron transfer material, and formed to have regions having different ratios of the passivation material and the transfer material with respect to the thickness direction.

[0008] The perovskite solar cell according to an embodiment of the present invention and the tandem solar cell including the same can have increased mechanical strength and improved power conversion efficiency.

[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 the composite layer of Figure 1.

[0011] FIG. 3 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.

[0012] Figure 4 is an enlarged view of the composite layer of Figure 3.

[0013] FIG. 5 is a cross-sectional view schematically illustrating another example of a tandem solar cell including a perovskite solar cell according to one embodiment of the present invention.

[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 photoactive layer containing a perovskite-based material disposed between the first electrode and the second electrode; and a composite layer disposed between the photoactive layer and the second electrode, containing a passivation material and an electron transfer material, and formed such that the ratio of the passivation material and the transfer material differs in a region with respect to the thickness direction.

[0015] In this embodiment, an electron transport layer disposed between the composite layer and the second electrode may be included.

[0016] In the present embodiment, the composite layer may be formed such that the ratio of the passivation material is higher than the ratio of the electron transfer material in one region facing the photoactive layer, and the ratio of the electron transfer material is higher than the ratio of the passivation material in another region closer to the second electrode than in the first region.

[0017] In this embodiment, the composite layer may be formed such that the ratio of the passivation material or the electron transfer material gradually changes with respect to the thickness direction of the composite layer.

[0018] In the present embodiment, the composite layer may be formed such that the proportion of the passivation material gradually increases with respect to the direction approaching the photoactive layer, and the proportion of the electron transfer material gradually increases with respect to the direction approaching the second electrode.

[0019] In the present embodiment, the composite layer comprises a first region facing the photoactive layer, a third region facing the second electrode, and a second region between them, wherein the first region comprises a passivation material, the second region comprises a passivation material and an electron transfer material, and the third region may comprise an electron transfer material.

[0020] In this embodiment, the ratio of the passivation material and the ratio of the electron transfer material may decrease and increase as one side closer to the first region moves toward the other side closer to the third region, based on the thickness direction of the composite layer.

[0021] In this embodiment, the ratio of the passivation material to the electron transfer material in the second region can gradually change from one side closer to the first region to the other side closer to the third region based on the thickness direction of the composite layer, in a ratio range of 0.5:0.5 to 0.1:0.9.

[0022] In the present embodiment, the passivation material may include one or more selected from LiF, KF, CsF, MgF2, AlOx, TiOx, HfOx, and ZrOx.

[0023] In this embodiment, the electron transfer material may include a fullerene-based material.

[0024] Another embodiment of the present invention for achieving the above-described purpose discloses a tandem solar cell comprising a silicon layer, a recombination layer on the silicon layer, an electrode disposed opposite to the recombination layer, a photoactive layer containing a perovskite-based material disposed between the recombination layer and the electrode, and a composite layer disposed between the photoactive layer and the second electrode and containing a passivation material and an electron transfer material, and formed to have regions having different ratios of the passivation material and the transfer material with respect to the thickness direction.

[0025] In this embodiment, an electron transport layer disposed between the composite layer and the electrode may be included.

[0026] In the present embodiment, the composite layer may be formed such that the ratio of the passivation material is higher than the ratio of the electron transfer material in one region facing the photoactive layer, and the ratio of the electron transfer material is higher than the ratio of the passivation material in another region closer to the electrode than in the one region.

[0027] In this embodiment, the composite layer may be formed such that the ratio of the passivation material or the electron transfer material gradually changes with respect to the thickness direction of the composite layer.

[0028] In the present embodiment, the composite layer may be formed such that the proportion of the passivation material gradually increases with respect to the direction approaching the photoactive layer, and the proportion of the electron transfer material gradually increases with respect to the direction approaching the second electrode.

[0029] In the present embodiment, the composite layer comprises a first region facing the photoactive layer, a third region facing the second electrode, and a second region between them, wherein the first region comprises a passivation material, the second region comprises a passivation material and an electron transfer material, and the third region may comprise an electron transfer material.

[0030] In this embodiment, the ratio of the passivation material and the ratio of the electron transfer material may decrease and increase as one side closer to the first region moves toward the other side closer to the third region, based on the thickness direction of the composite layer.

[0031] In this embodiment, the ratio of the passivation material to the electron transfer material in the second region can gradually change from one side closer to the first region to the other side closer to the third region based on the thickness direction of the composite layer, in a ratio range of 0.5:0.5 to 0.1:0.9.

[0032] In the present embodiment, the passivation material may include one or more selected from LiF, KF, CsF, MgF2, AlOx, TiOx, HfOx, and ZrOx.

[0033] In this embodiment, the electron transfer material may include a fullerene-based material.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] In the following examples, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] One embodiment of the present invention relates to a perovskite solar cell, and another embodiment relates to a tandem solar cell. Various examples of perovskite solar cells and tandem solar cells are schematically illustrated in FIGS. 1 to 5.

[0043] FIG. 1 is a cross-sectional view schematically illustrating an example of a perovskite solar cell according to one embodiment of the present invention.

[0044] Referring to FIG. 1, a perovskite solar cell (1) may include a substrate (10), a first electrode (20), a composite layer (50), a photoactive layer (40), and a second electrode (80).

[0045] 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 between the first electrode (20) and the photoactive layer (40), and as a specific example, may include a hole transport layer (30).

[0046] Additionally, a transparent electrode (70) may be included between the electron transport layer (60) and the second electrode (80).

[0047] Additionally, as an optional embodiment, one or more anti-reflective films on the transparent electrode (70) may be further included.

[0048] 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.

[0049] 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.

[0050] A substrate (10) may be placed on a bottom surface to form a perovskite solar cell (1) and may include any one selected from glass, for example, borosilicate glass or quartz glass, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyimide (PI), polycarbonate (PC), polypropylene (PP), triacetylcellulose (TAC), or polyethersulfone (PES), but is not limited thereto.

[0051] The first electrode (20) can be placed on the substrate (10) and can be formed of various conductive materials, for example, a conductive material having light transparency.

[0052] As a specific example, the first electrode (20) may include a transparent conductive oxide, a carbonaceous conductive material, and a metallic material. Examples of transparent conductive oxides may 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.

[0053] As the carbonaceous conductive material, for example, graphene or carbon nanotubes may be used, and as the metallic material, for example, metal (Ag) nanowires or metal thin films with a multilayer structure such as Au / Ag / Cu / Mg / Mo / Ti may be used.

[0054] 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 structure can also be varied, such as being single-layer or multi-layered.

[0055] The hole transport layer (30) may be a layer formed on the first electrode (20) to which holes formed in the perovskite photoactive 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.

[0056] 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.

[0057] A photoactive 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.

[0058] At this time, electrons formed in the perovskite photoactive layer (40) are transferred to the composite layer (50) described later, and holes formed in the perovskite photoactive layer (40) can be transferred to the hole transport layer (30).

[0059] For example, the perovskite photoactive layer (40) may have an organic-inorganic hybrid perovskite structure represented by the chemical formula ABX3 (wherein A may be a monovalent organic cation or metal cation, B may be a divalent metal cation, and X may be a halogen anion).

[0060] As a specific example, the perovskite photoactive 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 photoactive 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).

[0061] The composite layer (50) can be formed on the perovskite photoactive layer (40) and may include a passivation material and an electron transfer material.

[0062] The composite layer (50) can, for example, prevent the metal oxide forming the electron transport layer (60) described later from oxidizing the perovskite compound constituting the photoactive layer, and can perform the role of easily extracting electrons from the photoactive layer (40) and transferring them to the electron transport layer (60) by aligning the energy bands with the perovskite photoactive layer (40).

[0063] Meanwhile, the passivation of the composite layer (50) may include one or more selected from LiF, KF, CsF, MgF2, AlOx, TiOx, HfOx, and ZrOx, and the electron transfer material may include a fullerene-based material.

[0064] Figure 2 is an enlarged view of the composite layer of Figure 1.

[0065] Referring to FIG. 2, the composite layer (50) may include a first region (51), a second region (52), and a third region (53).

[0066] The first region (51) may include a passivation material, and this passivation material may serve to protect the perovskite-based compound of the photoactive layer (40).

[0067] The second region (52) may include a passivation material and an electron transfer material. For example, the ratio of the passivation material and the electron transfer material in the second region (52) may differ based on the thickness direction. As a specific example, in the second region (52), one side (A) that is closer to the first region (51) based on the region may have a higher ratio of the passivation material than the ratio of the electron transfer material, and the other side (B) that is closer to the third region (53) may have a higher ratio of the electron transfer material than the ratio of the passivation material.

[0068] As a specific example, the composite layer (50) includes a passivation material and a fullerene-based material, and the ratio of the passivation material and the fullerene-based material can gradually change based on the thickness direction of the second region (52).

[0069] As a specific example, the ratio of passivation material to fullerene-based material can gradually change from one side (A) closer to the first region (51) to the other side (B) closer to the third region (53) based on the thickness direction of the second region (52).

[0070] At this time, as one side (A) close to the first region (51) moves toward the other side (B) close to the third region (53), the proportion of the passivation material decreases, and the proportion of the fullerene-based material may increase.

[0071] Thus, the ratio of passivation material that decreases as one side (A) closer to the first region (51) in the thickness direction of the second region (52) moves toward the other side (B) closer to the third region (53), and the ratio of fullerene-based material that increases as one side (A) closer to the first region (51) in the thickness direction of the second region (52) moves toward the other side (B) closer to the third region (53) can be formed by gradually changing within a ratio range of 0.5:0.5 to 0.1:0.9.

[0072] For example, in the second region (52), the ratio of passivation material to electron transfer material can be continuously present with a concentration gradient from a region of 0.5:0.5 to a region of 0.1:0.9, gradually changing from one side (A) closer to the first region (51) to the other side (B) closer to the third region (53) based on the thickness direction of the second region (52).

[0073] Meanwhile, if the ratio of the passivation material to the electron transport material is less than 0.5:0.5, the amount of the passivation material increases, and insulating properties are exhibited, hindering electron transport. Consequently, electrons generated in the photoactive layer cannot move, and holes recombine, which may reduce the Fill Factor (FF) value of the device. If the ratio of the passivation material to the electron transport material exceeds 0.1:0.9, the amount of the spherical fullerene-based material increases, and the density of the thin film decreases, which may reduce the open-circuit voltage (Voc) and FF value of the device.

[0074] Meanwhile, the thickness of the second region (52) may be 1 nm to 15 nm. If the thickness of the second region (52) is less than 1 nm, it may not have the form of a thin film, so the effect of improving the density of the film cannot be expected, and it may be difficult to control the work function value, and it may be difficult to block holes generated from the photoactive layer (40), so electrons and holes recombine, which may reduce the performance of the device. If the thickness of the second region (52) is greater than 15 nm, the electron transfer characteristics may decrease due to the light absorption characteristics of carbon materials such as fullerene-based materials, which may reduce the performance of the device.

[0075] The third region (53) may include a fullerene-based material, and this fullerene-based material may serve to transfer electrons generated in the photoactive layer (40) to the electron transport layer (60).

[0076] Meanwhile, the thickness of the third region (53) may be 0 nm to 15 nm, and since the second region (52) includes an electron transfer material, the third region (53) may not need to be formed separately, and if the thickness of the third region (53) exceeds 15 nm, the electron transfer characteristics may decrease due to the light absorption characteristics of the carbon material, such as a fullerene-based material, and thus the performance of the device may decrease.

[0077] Meanwhile, the first region (51) of the composite layer (50) may have a thickness of 0 nm to 2 nm, and since the second region (52) includes a passivation material, the first region (51) may not need to be formed separately, and if the thickness of the first region (51) exceeds 2 nm, insulating properties are exhibited, hindering electron transfer, so that electrons generated in the photoactive layer cannot move and recombine with holes, which may reduce the efficiency of the device.

[0078] The composite layer (50) can be formed, for example, using a thermal evaporation method, and the first region (51), second region (52), and third region (53) of the composite layer (50) can be formed in the same chamber using a thermal evaporation method with a dual source, that is, a source containing a passivation material and a source containing an electron transfer material. At this time, the second region (52) can be manufactured as a gradient thin film having a concentration gradient of the passivation material and the electron transfer material by depositing the dual source by adjusting the injection amounts differently.

[0079] Ratio Atomic percent Region 1 Region 2 Region 3 LiFC60LiFC60LiFC60SiOCLiF Comparative Example 1 00 10 10.8 1.1 9 7.9 0.10.1 Example 1 1 00 10.9 10.3 1.1 9 8 0.3 0.3 Example 2 1 00 30.7 10.3 1 9 5.2 1.9 1.6 Example 3 1 00 50 50 10.2 1 9 2.9 3.2 2.7

[0080] Table 1 shows the atomic percent of elements measured by XPS analysis of the composite layer (50) prepared according to the ratio of the passivation material and electron transfer material in the second region of the composite layer (50) and the comparative example. (At this time, the composite layer (50) may be formed on a Si wafer.) XPS analysis can provide information about the surface of about 10 nm, and if the density of the composite layer (50) is low or there are pores, information about the lower surface is included. Therefore, when XPS analysis is performed after thermally depositing the Examples 1 to 3 and the comparative example on a Si wafer with the same thickness, more Si contained in the Si wafer may be detected when the thin film density is low, and conversely, less Si may be detected when the thin film density is high. That is, it may be possible to estimate the density of the thin film based on the amount of Si detected.

[0081] Referring to Table 1, it can be seen that the atomic percent of the composite layer (50) prepared in Examples 1 to 3 and the Comparative Example is 0.2 for the detected Si in Example 3, where the ratio of LiF to C60 in the second region is 0.5:0.5. This is a lower value compared to Example 1, Example 2 and the Comparative Example, and it can be seen that the density of the composite layer (50) prepared in Example 2 is higher than that of Example 1, Example 2 and the Comparative Example.

[0082] In addition, Examples 1 and 2, in which the ratio of LiF to C60 in the second region is 0.1:0.9 and 0.3:0.7, respectively, show that the detected Si is 0.3, which is higher than the Si detected in the comparative example in which the ratio of LiF to C60 in the second region is 0.1:0.8.

[0083] In other words, compared to when the passivation material and the electron transport material are formed as separate layers, it can be seen that the density of the thin film increases further when the passivation material and the electron transport material are formed in a constant ratio.

[0084] Meanwhile, as the density of the thin film increases, the mechanical strength of the thin film can also increase.

[0085] Region 1 Region 2 Region 3 Device parameterLiFC60LiFC60LiFC60Voc[V]JSC_AR[mA / cm 2 ]FF[%]PCE[%]Hi[%]Comparative Example 1 00 10 11.7 12 18.38 73.5 72 3.1 5 5.26 Example 1 100 10.9 11.7 50 18.38 74.5 23.9 65.81 Example 2 100 30.7 11.8 418.32 73.8 72 4.4 15.64 Example 3 100 50.5 11.8 11 18.5 8 76.5 25.7 63.59 Example 4 100 70.30 11.7 58 18.9 271.8 72 3.9 14.00

[0086] Table 2 shows the parameters of a solar cell including a composite layer (50) prepared in Examples 1 to 4 and a comparative example according to the ratio of the passivation material and the electron transfer material in the second region (52) of the composite layer (50). Referring to Table 2, it can be confirmed that the parameters of the solar cell including the composite layer (50) prepared in Examples 1 to 4 and a comparative example are the best compared to Examples 1, 2, 4 and the comparative example, with the open-circuit voltage (Voc), FF value, and PCE value of the solar cell including Example 3, in which the ratio of LiF to C60 in the second region is 0.5:0.5, being 1.811V, 18.58%, and 25.76%, respectively. This implies that, in relation to the fact that the thin film density of Example 3 in Table 1 was the best, as the thin film density of the composite layer (50) increases, the Voc and FF of the solar cell increase, thereby improving the photoelectric conversion characteristics.

[0087] In addition, it can be confirmed that the parameters of the solar cell including Example 1 and Example 2, in which the ratio of LiF to C60 in the second region is 0.1:0.9 and 0.3:0.7, respectively, are superior to the parameters of the solar cell including the comparative example in which the ratio of LiF to C60 in the second region is 0:1, and from this, it can be confirmed that the photoelectric conversion characteristics of the solar cell improve as the thin film density of the composite layer (50) increases.

[0088] Meanwhile, in the case of Example 4, where the ratio of LiF to C60 is 0.7:0.3, the amount of LiF becomes greater than that of C60, so insulating properties are exhibited, preventing electrons generated in the photoactive layer from moving and causing them to recombine with holes, which can be interpreted as actually decreasing the FF value of the solar cell.

[0089] Meanwhile, the composite layer (50) according to an embodiment of the present invention can be manufactured in a gradient shape having a concentration gradient as the ratio of LiF and C60 in the second region (52) gradually changes. At this time, the ratio of LiF and C60 in the second region (52) can be manufactured in a gradient shape having a concentration gradient as it gradually changes from 0.5:0.5 to 0.1:0.9 as in Examples 1 to 3, so that the thin film density of the composite layer (50) can be confirmed to increase through Examples 1 to 3, and the photoelectric conversion characteristics of the solar cell including such a composite layer (50) can be confirmed to be improved.

[0090] In addition, if the second region (52) of the composite layer (50) is manufactured in a gradient shape having a concentration gradient, it may be possible to control the work function of the composite layer (50), making it easy to align with the energy band of the perovskite photoactive layer (40), and also easy to align with the energy band of the electron transport layer (60), thereby strengthening the transfer of electrons within the solar cell and increasing the power conversion efficiency of the device.

[0091] The electron transport layer (60) may be formed on the composite layer (50) and may include a metal oxide. For example, the metal oxide may have superior electron transport characteristics compared to a fullerene-based material. However, if it is located directly on the photoactive layer (40) containing a perovskite compound, there is a risk of oxidizing the perovskite compound, and since the energy band alignment with the perovskite compound is not correct, it may be difficult to extract electrons from the photoactive layer (40). Therefore, it is additionally formed on the composite layer (50) so that electrons transferred from the composite layer (50) can be received using the superior electron transport characteristics and easily transferred to the second electrode (80) described later.

[0092] For example, the electron transport layer (60) may include one or more selected from SnOx, TiOx, ZnOx, WOx, NbOx, InOx, AlOx, HfOx, BaSnOx, ZrOx, VOx, and CeOx, and specifically, SnOx may be included.

[0093] The electron transport layer (60) containing SnOx can exhibit excellent adhesion characteristics with the third region (53) of the composite layer (50) containing a hydrophobic fullerene-based material, and the process for forming the thin film can be carried out at a relatively low temperature to prevent damage to the fullerene-based material that is sensitive to heat.

[0094] The electron transport layer (60) can be formed using various methods, specifically at a low temperature using atomic layer deposition (ALD), and can stably secure the desired shape and characteristics.

[0095] Meanwhile, by using atomic layer deposition (ALD) to perform the thin film process at a low temperature, the photoactive layer (40) formed from a heat-sensitive perovskite compound can be prevented from being damaged by heat, thereby preventing a decrease in the performance of the solar cell device.

[0096] 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.

[0097] An anti-reflective film may be further included as an optional embodiment, and the anti-reflective film is placed on the transparent electrode (70) to 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).

[0098] For example, the anti-reflective film may include fluorine (F), which has high light transmittance and a very low refractive index, and may include LiF as an optional embodiment.

[0099] The second electrode (80) can be formed on the transparent electrode (70) and can serve to electrically connect the perovskite solar cell (1) to the outside.

[0100] For example, the second electrode (80) can be formed from a metallic material such as silver (Ag), gold (Au), copper (Cu), magnesium (Mg), molybdenum (Mo), and titanium (Ti), and a pattern of a certain shape can be formed so that sunlight can enter into the cell.

[0101] Consequently, the perovskite solar cell according to an embodiment of the present invention includes a composite layer having both electron transport characteristics and passivation characteristics, thereby increasing the density of the composite layer, which can increase the mechanical strength of the composite layer, and by enabling the control of the work function, the range of candidates for photoactive layers, electrodes, or electron transport layers that can be disposed on both sides of the composite layer can be expanded, and the power conversion efficiency of the device can be increased by further enhancing electron transport within the device.

[0102] FIG. 3 is a cross-sectional view schematically illustrating another example of a tandem solar cell including a perovskite solar cell according to one embodiment of the present invention.

[0103] Referring to FIG. 3, a tandem solar cell (2) including a perovskite solar cell (2000) may include a silicon layer (120), a recombination layer (140) formed on the silicon layer (120), a perovskite photoactive layer (170), a composite layer (180) formed on the perovskite photoactive layer (170), and a second electrode (210).

[0104] Additionally, the perovskite solar cell (2000) may include one or more additional layers as an optional embodiment, for example, a hole transport layer (150) between the recombination layer (140) and the photoactive layer (170). Also, as an example, a transparent electrode (200) may be included between the composite layer (180) and the second electrode (210).

[0105] Additionally, as an optional embodiment, a SAM layer (160) on the hole transport layer (150) may be further included.

[0106] Meanwhile, referring specifically to FIG. 3, the tandem solar cell (2) may include a silicon solar cell (lower cell) (1000) and a perovskite solar cell (upper cell) (2000) formed on the silicon solar cell (1000), and may include a recombination layer (140) between the silicon solar cell (1000) and the perovskite solar cell (2000) that joins the two and electrically connects them.

[0107] This recombination layer (140) can 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 underneath without transmission loss.

[0108] 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 (ME) of a metal or metal alloy disposed on the substrate, a BSF layer (110) disposed on the back electrode (ME), a silicon layer (120) disposed on the BSF layer (110), and an emitter layer (130) disposed on the silicon layer (120).

[0109] At this time, the back electrode (ME) may include silver (Ag), titanium (Ti), gold (Au), etc.

[0110] The BSF (Back Surface Field) layer (110) is placed on the back electrode (ME) so that electrons and holes generated in the silicon layer (120) and the emitter layer (130) can be transferred to the outside through the back electrode (ME).

[0111] The silicon layer (120) is disposed on the BSF layer (110) and may have one of the known silicon solar cell semiconductor layer structures, but is not limited to a specific structure. For example, the silicon layer (120) may include 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).

[0112] The emitter layer (130) may include an n-type material or a p-type material depending on the material that is disposed on the silicon layer (120) and constitutes the recombination layer (140) described later.

[0113] According to such an embodiment of the present invention, the structure of the silicon solar cell (1000) is such that n on the surface of p-type silicon ++ Al-BSF (Aluminum Back Surface Field), PERC (Passivated Emitter and Rear Cell), PERT (Passivated Emitter Rear Totally Diffusing), and PERL (Passivated Emitter and Rear Locally Diffusing) structures or SiOx tunneling layer / n formed through emitter formation ++ It is not particularly limited because it can be a TOPCon (Tunnel oxide passivated contact) structure through poly-Si formation, etc.

[0114] A perovskite solar cell (2000) may include a perovskite photoactive layer (170) disposed on a recombination layer (140), a composite layer (180) formed on the perovskite photoactive layer (170), and an electrode (210).

[0115] Additionally, the perovskite solar cell (2000) may further include one or more layers as an optional embodiment, for example, a hole transport layer (150) between the recombination layer (140) and the photoactive layer (170). Additionally, as an example, an electron transport layer (190) may be included between the composite layer (180) and the electrode (210), and a transparent electrode (200) disposed on the electron transport layer (190) may be further included.

[0116] Additionally, as an optional embodiment, it may further include a SAM layer (160) disposed on the hole transport layer (150) and one or more anti-reflection films disposed on the transparent electrode (200).

[0117] The recombination layer (140) can be formed from a conductive material, for example, a conductive material having light transparency, and may include, for example, a transparent conductive oxide, a carbonaceous conductive material and a metallic material. As a 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.

[0118] The hole transport layer (150) may be a layer formed on the recombination layer (140) to which holes generated in the perovskite photoactive layer (170) described later are transported. For example, the hole transport layer (150) 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.

[0119] 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.

[0120] As an optional embodiment, a SAM layer (160) may be disposed on the hole transport layer (150).

[0121] The SAM layer (160) may include a self-assembled organic material having the characteristics of a p-type semiconductor and can improve the mobility characteristics of holes generated in the perovskite photoactive layer (170).

[0122] A photoactive layer (170) containing a perovskite-based material can be formed on a hole transport layer (150), 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 photoactive layer (170) are transferred to a composite layer (180) described later, and holes formed in the perovskite photoactive layer (170) can be transferred to the hole transport layer (150).

[0123] For example, the perovskite photoactive layer (170) 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).

[0124] As a specific example, the perovskite photoactive layer (170) 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 photoactive 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).

[0125] The composite layer (180) can be formed on the perovskite photoactive layer (170) and may include both a passivation material and an electron transfer material.

[0126] The composite layer (180) can, for example, prevent the metal oxide forming the electron transport layer (190) described later from oxidizing the perovskite compound constituting the photoactive layer, and can perform the role of easily extracting electrons from the photoactive layer (170) and transferring them to the electron transport layer (190) by aligning the energy bands with the perovskite photoactive layer (170).

[0127] Meanwhile, the passivation material of the composite layer (180) may include one or more selected from LiF, KF, CsF, MgF2, AlOx, TiOx, HfOx, and ZrOx, and the electron transfer material may include a fullerene-based material.

[0128] Figure 4 is an enlarged view of the composite layer of Figure 3.

[0129] Referring to FIG. 4, the composite layer (180) may include a first region (181), a second region (182), and a third region (183).

[0130] The first region (181) may include a passivation material, and this passivation material may serve to protect the perovskite-based compound of the photoactive layer (170).

[0131] The second region (182) may include a passivation material and an electron transfer material. For example, the ratio of the passivation material and the electron transfer material in the second region (52) may differ based on the thickness direction. As a specific example, in the second region (52), one side (A) that is closer to the first region (51) based on the region may have a higher ratio of the passivation material than the ratio of the electron transfer material, and the other side (B) that is closer to the third region (53) may have a higher ratio of the electron transfer material than the ratio of the passivation material.

[0132] As a specific example, the composite layer (50) includes a passivation material and a fullerene-based material, and the ratio of the passivation material and the fullerene-based material can gradually change based on the thickness direction of the second region (52).

[0133] As a specific example, the ratio of passivation material to fullerene-based material may gradually change from one side (A) closer to the first region (181) to the other side (B) closer to the third region (183) based on the thickness direction of the second region (182).

[0134] At this time, as one side (A) close to the first region (181) moves toward the other side (B) close to the third region (183), the proportion of the passivation material decreases and the proportion of the fullerene-based material increases.

[0135] Thus, the ratio of passivation material that decreases as one side (A) closer to the first region (181) in the thickness direction of the second region (182) moves toward the other side (B) closer to the third region (183), and the ratio of fullerene-based material that increases as one side (A) closer to the first region (181) in the thickness direction of the second region (182) moves toward the other side (B) closer to the third region (183), can be formed by gradually changing within a ratio range of 0.5:0.5 to 0.1:0.9.

[0136] For example, in the second region (182), the ratio of passivation material to electron transfer material can be continuously present with a concentration gradient from a region of 0.5:0.5 to a region of 0.1:0.9, gradually changing from one side (A) closer to the first region (181) to the other side (B) closer to the third region (183) based on the thickness direction of the second region (182).

[0137] Meanwhile, if the ratio of the passivation material to the electron transport material is less than 0.5:0.5, the amount of the passivation material increases, and insulating properties are exhibited, hindering electron transport. Consequently, electrons generated in the photoactive layer cannot move and holes recombine, which may reduce the Fill Factor (FF) value of the device. If the ratio of the passivation material to the electron transport material exceeds 0.1:0.9, the amount of the spherical fullerene-based material increases, causing the density of the thin film to decrease, which may reduce the open-circuit voltage (Voc) and FF value of the device.

[0138] Meanwhile, the thickness of the second region (182) may be 1 nm to 15 nm. If the thickness of the second region (182) is less than 1 nm, it may not have the form of a thin film, so the effect of improving the density of the film cannot be expected, and it may be difficult to control the work function value, and it may be difficult to block holes generated from the photoactive layer (170), so electrons and holes recombine, which may reduce the performance of the device. If the thickness of the second region (182) is greater than 15 nm, the electron transport characteristics may decrease due to the light absorption characteristics of carbon materials such as fullerene-based materials, which may reduce the performance of the device.

[0139] The third region (183) may include a fullerene-based material, and this fullerene-based material may serve to transfer electrons generated in the photoactive layer (170) to the electron transport layer (190).

[0140] Meanwhile, the thickness of the third region (183) may be 0 nm to 15 nm, and since the second region (182) includes an electron transfer material, the third region (183) may not need to be formed separately, and if the thickness of the third region (183) exceeds 15 nm, the electron transfer characteristics may decrease due to the light absorption characteristics of the carbon material, such as a fullerene-based material, and thus the performance of the device may decrease.

[0141] Meanwhile, the first region (181) of the composite layer (180) may have a thickness of 0 nm to 2 nm, and since the second region (182) includes a passivation material, the first region (181) may not need to be formed separately, and if the thickness of the first region (181) exceeds 2 nm, insulating properties are exhibited, hindering electron transfer, so that electrons generated in the photoactive layer cannot move and recombine with holes, which may reduce the efficiency of the device.

[0142] The composite layer (180) can be formed, for example, using a thermal evaporation method, and the first region (181), second region (182), and third region (183) of the composite layer (180) can be formed in the same chamber using a thermal evaporation method with a dual source, that is, a source containing a passivation material and a source containing an electron transfer material. At this time, the second region (182) can be manufactured as a gradient thin film having a concentration gradient of the passivation material and the electron transfer material by depositing the dual source by adjusting the injection amounts differently.

[0143] Ratio Atomic percent Region 1 Region 2 Region 3 LiFC60LiFC60LiFC60SiOCLiF Comparative Example 1 00 10 10.8 1.1 9 7.9 0.10.1 Example 1 1 00 10.9 10.3 1.1 9 8 0.3 0.3 Example 2 1 00 30.7 10.3 1 9 5.2 1.9 1.6 Example 3 1 00 50 50 10.2 1 9 2.9 3.2 2.7

[0144] Table 3 shows the atomic percentage of elements measured by XPS analysis of the composite layer (180) prepared according to the ratio of the passivation material and the electron transfer material in the second region of the composite layer (180) and the comparative example. (At this time, the composite layer (180) may be formed on a Si wafer.) XPS analysis can provide information about the surface of about 10 nm, and if the density of the composite layer (180) is low or there are pores, information about the lower surface is included. Therefore, when XPS analysis is performed after thermally depositing the Examples 1 to 3 and the comparative example on a Si wafer with the same thickness, more Si contained in the Si wafer may be detected when the thin film density is low, and conversely, less Si may be detected when the thin film density is high. That is, it may be possible to estimate the density of the thin film based on the amount of Si detected.

[0145] Referring to Table 3, it can be seen that the atomic percent of the composite layer (180) prepared in Examples 1 to 3 and the Comparative Example is 0.2 for the detected Si in Example 3, where the ratio of LiF to C60 in the second region is 0.5:0.5. This is a lower value compared to Example 1, Example 2 and the Comparative Example, and it can be seen that the density of the composite layer (180) prepared in Example 2 is higher than that of Example 1, Example 2 and the Comparative Example.

[0146] In addition, Examples 1 and 2, in which the ratio of LiF to C60 in the second region is 0.1:0.9 and 0.3:0.7, respectively, show that the detected Si is 0.3, which is higher than the Si detected in the comparative example in which the ratio of LiF to C60 in the second region is 0.1:0.8.

[0147] In other words, compared to when the passivation material and the electron transport material are formed as separate layers, it can be seen that the density of the thin film increases further when the passivation material and the electron transport material are formed in a constant ratio.

[0148] Meanwhile, as the density of the thin film increases, the mechanical strength of the thin film can also increase.

[0149] Region 1 Region 2 Region 3 Device parameterLiFC60LiFC60LiFC60Voc[V]JSC_AR[mA / cm 2 ]FF[%]PCE[%]Hi[%]Comparative Example 1 00 10 11.7 12 18.38 73.5 72 3.1 5 5.26 Example 1 100 10.9 11.7 50 18.38 74.5 23.9 65.81 Example 2 100 30.7 11.8 418.32 73.8 72 4.4 15.64 Example 3 100 50.5 11.8 11 18.5 8 76.5 25.7 63.59 Example 4 100 70.30 11.7 58 18.9 271.8 72 3.9 14.00

[0150] Table 4 shows the parameters of a solar cell including a composite layer (180) prepared in Examples 1 to 4 and a comparative example according to the ratio of the passivation material and the electron transfer material in the second region (182) of the composite layer (180). Referring to Table 4, it can be confirmed that the parameters of the solar cell including the composite layer (180) prepared in Examples 1 to 4 and a comparative example are the best compared to Examples 1, 2, 4 and the comparative example, with the open-circuit voltage (Voc), FF value, and PCE value of the solar cell including Example 3, in which the ratio of LiF to C60 in the second region is 0.5:0.5, being 1.811V, 18.58%, and 25.76%, respectively. This implies that, in relation to the fact that the thin film density of Example 3 in Table 1 was the best, as the thin film density of the composite layer (180) increases, the Voc and FF of the solar cell increase, thereby improving the photoelectric conversion characteristics.

[0151] In addition, it can be confirmed that the parameters of the solar cell including Example 1 and Example 2, in which the ratio of LiF to C60 in the second region is 0.1:0.9 and 0.3:0.7, respectively, are superior to the parameters of the solar cell including the comparative example in which the ratio of LiF to C60 in the second region is 0:1, and from this, it can be confirmed that the photoelectric conversion characteristics of the solar cell improve as the thin film density of the composite layer (180) increases.

[0152] Meanwhile, in the case of Example 4, where the ratio of LiF to C60 is 0.7:0.3, the amount of LiF becomes greater than that of C60, so insulating properties are exhibited, preventing electrons generated in the photoactive layer from moving and causing them to recombine with holes, which can be interpreted as actually decreasing the FF value of the solar cell.

[0153] Meanwhile, the composite layer (180) according to an embodiment of the present invention can be manufactured in a gradient shape having a concentration gradient as the ratio of LiF and C60 in the second region (182) gradually changes. At this time, the ratio of LiF and C60 in the second region (182) can be manufactured in a gradient shape having a concentration gradient as it gradually changes from 0.5:0.5 to 0.1:0.9, as in Examples 1 to 3, so that the thin film density of the composite layer (180) can be confirmed to increase through Examples 1 to 3, and the photoelectric conversion characteristics of the solar cell including such a composite layer (180) can be confirmed to be improved.

[0154] In addition, if the second region (182) of the composite layer (180) is manufactured in a gradient shape having a concentration gradient, it may be possible to control the work function of the composite layer (180), making it easy to align with the energy band of the perovskite photoactive layer (170), and also easy to align with the energy band of the electron transport layer (190), thereby strengthening the transfer of electrons within the solar cell and increasing the power conversion efficiency of the device.

[0155] The electron transport layer (190) may be formed on the composite layer (180) and may include a metal oxide. For example, the metal oxide may have superior electron transport characteristics compared to fullerene-based materials. However, if it is located directly on the photoactive layer (170) containing a perovskite compound, there is a risk of oxidizing the perovskite compound, and since the energy band alignment with the perovskite compound is not correct, it may be difficult to extract electrons from the photoactive layer (170). Therefore, it is additionally formed on the composite layer (180) so that electrons transferred from the composite layer (180) can be received using the superior electron transport characteristics and easily transferred to the second electrode (210) described later.

[0156] For example, the electron transport layer (190) may include one or more selected from SnOx, TiOx, ZnOx, WOx, NbOx, InOx, AlOx, HfOx, BaSnOx, ZrOx, VOx, and CeOx, and specifically, SnOx may be included.

[0157] The electron transport layer (190) containing SnOx can exhibit excellent adhesion characteristics with the third region (183) of the composite layer (180) containing a hydrophobic fullerene-based material, and the process for forming the thin film can be carried out at a relatively low temperature to prevent damage to the fullerene-based material that is sensitive to heat.

[0158] The electron transport layer (190) can be formed using various methods, specifically at a low temperature using atomic layer deposition (ALD), and can stably secure the desired shape and characteristics.

[0159] Meanwhile, by using atomic layer deposition (ALD) to perform the thin film process at a low temperature, the photoactive layer (170) formed from a heat-sensitive perovskite compound can be prevented from being damaged by heat, thereby preventing a decrease in the performance of the solar cell device.

[0160] The transparent electrode (200) can be formed on the electron transport layer (190) 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.

[0161] An anti-reflective film may be further included as an optional embodiment, and the anti-reflective film is placed on the transparent electrode (200) to 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 (2000), and furthermore, can improve the efficiency of the tandem solar cell (2) including the perovskite solar cell (2000).

[0162] For example, the anti-reflective film may include fluorine (F), which has high light transmittance and a very low refractive index, and may include LiF as an optional embodiment.

[0163] The second electrode (210) can be formed on the transparent electrode (200) and can serve to electrically connect the perovskite solar cell (2000) to the outside.

[0164] For example, the second electrode (210) can be formed from a metallic material such as silver (Ag), gold (Au), copper (Cu), magnesium (Mg), molybdenum (Mo) and titanium (Ti), and can be formed in a grid pattern so that sunlight can enter the cell.

[0165] FIG. 5 is a cross-sectional view schematically illustrating another example of a tandem solar cell including a perovskite solar cell according to one embodiment of the present invention.

[0166] Referring to FIG. 5, a tandem solar cell (3) including a perovskite solar cell (2000') may include a silicon layer (120'), a recombination layer (140') formed on the silicon layer (120'), a perovskite photoactive layer (170'), a composite layer (180') formed on the perovskite photoactive layer (170'), and a second electrode (210').

[0167] Additionally, the perovskite solar cell (2000') may further include one or more layers as an optional embodiment, for example, a hole transport layer (150') between the recombination layer (140') and the photoactive layer (170'). Also, as an example, a transparent electrode (200') may be included between the composite layer (180') and the second electrode (210').

[0168] Additionally, as an optional embodiment, a SAM layer (160') on the hole transport layer (150') may be further included.

[0169] Since the tandem solar cell (3) including the perovskite solar cell has the same configuration as the tandem solar cell (2) including the perovskite solar cell described above, a detailed description will be omitted, and only the parts that differ will be described.

[0170] A tandem solar cell (3) including a solar cell may include a form in which at least some layers are textured to improve light efficiency. By such textured at least some layers, an uneven surface is formed in the direction of incident light, and the light scattering effect of the light incident through the uneven surface increases the path of light incident on the perovskite photoactive layer (170'), thereby improving light collection and 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°.

[0171] In addition, by placing a composite layer (180') having both electron transport characteristics and passivation characteristics on the perovskite photoactive layer (170'), the density of the composite layer can be increased, thereby increasing the mechanical strength of the composite layer and allowing the work function to be controlled, which can expand the range of candidates for photoactive layers, electrodes, or electron transport layers that can be placed on both sides of the composite layer, and by further strengthening the transfer of electrons within the device, the power conversion efficiency of the device can be increased.

[0172] As a result, the perovskite solar cell according to the embodiment of the present invention and the tandem solar cell including the same include a composite layer having both electron transport characteristics and passivation characteristics, thereby increasing the density of the composite layer, which can increase the mechanical strength of the composite layer, and by enabling the control of the work function, the range of candidates such as photoactive layers, electrodes, or electron transport layers that can be placed on both sides of the composite layer can be expanded, and the power conversion efficiency of the device can be increased by further strengthening the transport of electrons within the device.

[0173] 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.

[0174] 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.

[0175] 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 photoactive layer containing a perovskite-based material disposed between the first electrode and the second electrode; and A perovskite solar cell comprising: a composite layer disposed between the photoactive layer and the second electrode, containing a passivation material and an electron transfer material, and formed to have regions having different ratios of the passivation material and the transfer material with respect to the thickness direction.

2. A perovskite solar cell according to claim 1, comprising an electron transport layer disposed between the composite layer and the second electrode.

3. In Paragraph 1, In the above composite layer, the ratio of the passivation material in one region facing the photoactive layer is higher than the ratio of the electron transfer material, and A perovskite solar cell comprising being formed such that the ratio of the electron transfer material is higher than the ratio of the passivation material in another region closer to the second electrode than in the first region.

4. In Paragraph 1, A perovskite solar cell comprising a composite layer formed such that the ratio of the passivation material or the electron transfer material gradually changes with respect to the thickness direction of the composite layer.

5. In Paragraph 4, A perovskite solar cell comprising a composite layer formed such that the ratio of the passivation material gradually increases with respect to the direction approaching the photoactive layer, and the ratio of the electron transfer material gradually increases with respect to the direction approaching the second electrode.

6. In Paragraph 1, The above composite layer includes a first region facing the photoactive layer, a third region facing the second electrode, and a second region between them. The first region above includes a passivation material, and The second region above includes a passivation material and an electron transfer material, and The above third region is a perovskite solar cell comprising an electron transfer material.

7. In Paragraph 6, A perovskite solar cell in which, in the second region, the ratio of the passivation material decreases and the ratio of the electron transfer material increases as one side closer to the first region moves toward the other side closer to the third region based on the thickness direction of the composite layer.

8. In Paragraph 7, A perovskite solar cell in which the ratio of the passivation material to the electron transfer material gradually changes in the range of 0.5:0.5 to 0.1:0.9 as it moves from one side closer to the first region to the other side closer to the third region, based on the thickness direction of the composite layer.

9. In Paragraph 1, The above passivation material comprises one or more selected from LiF, KF, CsF, MgF2, AlOx, TiOx, HfOx, and ZrOx, in a perovskite solar cell.

10. In Paragraph 1, The above electron transfer material is a perovskite solar cell comprising a fullerene-based material.

11. Silicon layer; A recombination layer on the above silicon layer; An electrode positioned to face the above recombination layer; A photoactive layer containing a perovskite-based material disposed between the recombination layer and the electrode; and A tandem solar cell comprising: a composite layer disposed between the photoactive layer and the electrode, containing a passivation material and an electron transfer material, and formed to have regions having different ratios of the passivation material and the transfer material with respect to the thickness direction.

12. In Paragraph 11, A tandem solar cell comprising an electron transport layer disposed between the composite layer and the electrode.

13. In Paragraph 11, The above composite layer is, In one region facing the photoactive layer, the ratio of the passivation material is higher than the ratio of the electron transfer material, and A tandem solar cell comprising being formed such that the ratio of the electron transfer material is higher than the ratio of the passivation material in another region closer to the electrode than in the first region.

14. In Paragraph 11, A tandem solar cell comprising a composite layer formed such that the ratio of the passivation material or the electron transfer material gradually changes with respect to the thickness direction of the composite layer.

15. In Paragraph 14, A tandem solar cell comprising a composite layer formed such that the ratio of the passivation material gradually increases with respect to the direction approaching the photoactive layer, and the ratio of the electron transfer material gradually increases with respect to the direction approaching the second electrode.

16. In Paragraph 11, The above composite layer includes a first region facing the photoactive layer, a third region facing the second electrode, and a second region between them. The first region above includes a passivation material, and The second region above includes a passivation material and an electron transfer material, and The above third region is a tandem solar cell comprising an electron transfer material.

17. In Paragraph 16, A tandem solar cell in which, in the second region, the ratio of the passivation material decreases and the ratio of the electron transfer material increases as one side closer to the first region moves toward the other side closer to the third region based on the thickness direction of the composite layer.

18. In Paragraph 17, A tandem solar cell in which the ratio of the passivation material to the electron transfer material gradually changes in the range of 0.5:0.5 to 0.1:0.9 as it moves from one side closer to the first region to the other side closer to the third region, based on the thickness direction of the composite layer.

19. In Paragraph 11, The above passivation material comprises one or more selected from LiF, KF, CsF, MgF2, AlOx, TiOx, HfOx, and ZrOx, forming a tandem solar cell.

20. In Paragraph 11, The above electron transfer material comprises a fullerene-based material, forming a tandem solar cell.

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