Method for manufacturing perovskite solar cell and perovskite solar cell manufactured therefrom

Abstract

The present invention relates to a method for manufacturing a perovskite solar cell and a perovskite solar cell manufactured using the method. More specifically, the present invention relates to a method for manufacturing a perovskite solar cell, including: (Step S1) a step of a) treating a hole transport layer (HTL) containing a substrate layer, a first electrode layer, and a metal oxide in a stacked structure with an oxidizing agent, b) treating with ultraviolet light and ozone, c) treating with oxygen plasma, or d) treating with nitrogen dioxide gas to oxidize the metal oxide; and (Step S2) a step of sequentially stacking a perovskite layer, an electron transport layer, and a second electrode layer on the hole transport layer in the stacked structure, and a perovskite solar cell manufactured using the method.

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a perovskite solar cell and a perovskite solar cell manufactured therefrom, and more particularly, to a method for manufacturing a perovskite solar cell that improves hole mobility in a hole transport layer while minimizing damage to other components, and a perovskite solar cell manufactured therefrom. [Background technology]

[0002] Solar cells are the core element of photovoltaic power generation, which directly converts sunlight into electricity, and are currently used in a wide range of applications, from homes to space. They are also being used in the fields of aviation, meteorology, and communications, and solar-powered cars and air conditioners are also attracting attention.

[0003] These solar cells mainly use silicon semiconductors, but the high cost of generating electricity is a problem due to the price of high-purity silicon semiconductor raw materials and the complexity of the manufacturing process of solar cell using it. In other words, the market is limited to growing with subsidies from various governments because the cost of generating electricity is 3 to 10 times higher than the conventional cost of generating electricity using fossil fuels. For this reason, research and development of solar cells that do not use silicon has been intensified, and since the 1990s, full-scale research has been conducted on dye-sensitized solar cells (DSSCs) that use organic semiconductor dyes and polymer solar cells that use conductive polymers. Despite many efforts from academia and industry, organic semiconductor-based solar cells such as DSSCs and polymer solar cells have not been able to reach the commercialization stage, but the recent emergence of perovskite solar cells (PSCs), which combine the advantages of DSSCs and polymer solar cells, has raised expectations for next-generation solar cells.

[0004] Perovskite solar cells are a hybrid solar cell between conventional DSSC and polymer solar cells. Unlike DSSC, they do not use liquid electrolytes, improving reliability. They also have high efficiency due to the optical superiority of perovskite. Recently, efficiency has been continuously improved through improvements in processes, materials, and structures.

[0005] 1 is a diagram showing a perovskite solar cell. Referring to FIG 1, the perovskite solar cell 100 is composed of a substrate layer 10, a first electrode layer 20, a hole transport layer 30, a perovskite layer 40, an electron transport layer 50 and a second electrode layer 60.

[0006] In the perovskite solar cell 100, the mobility of electrons or holes in each layer is important, but the extraction of charge at the interface between each layer is also very important. If the charge cannot be extracted quickly at the interface, the phenomenon of recombination of electrons and holes occurs.

[0007] For example, NiOx contained in the hole transport layer 30 has a high hole mobility in the material compared to an organic hole transporter, but it cannot efficiently extract holes at the interface with the perovskite layer 40, which may adversely affect the characteristics of the solar cell 100. In order to improve the hole extraction rate, it is possible to adjust Ni vacancies by using additives or by using high heat, but ITO (Indium tin oxide), which is mainly used as the substrate layer 10 or the first electrode layer 20 laminated on the lower surface of the hole transport layer 30, is damaged by high-temperature heat treatment, such as a significant increase in resistance at temperatures above 200°C, so there is a need for an improvement method for improving the hole extraction rate without damaging the substrate layer 10 or the first electrode layer 20. Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a method for manufacturing a perovskite solar cell that improves the hole mobility and hole extraction rate of a hole transport layer while minimizing damage to a substrate layer or an electrode layer, and a perovskite solar cell manufactured using the same. [Means for solving the problem]

[0009] To achieve the above object, a method for manufacturing a perovskite solar cell according to one aspect of the present invention includes: (Step S1) a step of a laminate having a substrate layer, a first electrode layer, and a hole transport layer (HTL) containing a metal oxide laminated in that order, the hole transport layer being a) treated with an oxidant, b) treated with ultraviolet light and ozone, c) treated with oxygen plasma, or d) treated with nitrogen dioxide gas to oxidize the metal oxide; and (Step S2) a step of sequentially laminating a perovskite layer, an electron transport layer, and a second electrode layer on the hole transport layer of the laminate.

[0010] Here, step S1 may further include treating the hole transport layer with a solution containing the oxidant to oxidize the metal oxide, and then removing a solvent contained in the solution.

[0011] The metal oxide in the step S1 is also NiOx.

[0012] At this time, in the above (Step S1), the NiOx is oxidized to increase the Ni vacancies in the hole transport layer.

[0013] In the step S1, the NiOx is oxidized to remove the Ni contained in the hole transport layer. 2+ Part of Ni 3+ It is oxidized to.

[0014] At this time, the Ni 3+ and the Ni content 2+ and Ni 3+ The ratio of the total content is 0.6 or less.

[0015] Meanwhile, the first electrode layer and the second electrode layer each independently include one or more selected from the group consisting of ITO (indium tin oxide), ICO (indium cerium oxide), IWO (indium tungsten oxide), ZITO (zinc indium tin oxide), ZIO (zinc indium oxide), ZTO (zinc tin oxide), GITO (gallium indium tin oxide), GIO (gallium indium oxide), GZO (gallium zinc oxide), AZO (aluminum doped zinc oxide), FTO (fluorine tin oxide), and ZnO.

[0016] The electron transport layer includes at least one selected from the group consisting of Ti oxide, Zn oxide, In oxide, Sn oxide, W oxide, Nb oxide, Mo oxide, Mg oxide, Zr oxide, Sr oxide, Yr oxide, La oxide, V oxide, Al oxide, Y oxide, Sc oxide, Sm oxide, Ga oxide, and SrTi oxide.

[0017] Meanwhile, a perovskite solar cell according to another aspect of the present invention is a solar cell in which a substrate layer, a first electrode layer, a hole transport layer (HTL) containing a metal oxide, a perovskite layer, an electron transport layer, and a second electrode layer are sequentially stacked, the metal oxide being NiOx, the hole transport layer being Ni 2+ and Ni 3+ Includes. Effect of the Invention

[0018] According to the present invention, the hole transport layer is not subjected to a high-temperature heat treatment of 200° C. or more, but is instead treated with a) an oxidizing agent, b) ultraviolet light and ozone, c) oxygen plasma, or d) nitrogen dioxide gas to oxidize the metal oxide contained in the hole transport layer, thereby improving the hole mobility or hole extraction rate of the hole transport layer without damaging the substrate layer or the electrode layer.

[0019] In this way, if the hole extraction efficiency of the hole transport layer is improved, recombination due to inefficient hole extraction at the interface with the perovskite layer can be prevented, ultimately improving the photoelectric conversion efficiency. [Brief description of the drawings]

[0020] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited only to the matters shown in such drawings.

[0021] [Figure 1] FIG. 1 is a side view showing a perovskite solar cell. [Diagram 2] 1 is a side view showing a laminate in which a substrate layer, a first electrode layer and a hole transport layer are laminated according to the present invention. [Diagram 3] FIG. 2 is a conceptual diagram showing that Ni vacancies in a hole transport layer are improved through an oxidant treatment according to an embodiment of the present invention. [Figure 4] 1 is a graph showing the results of UPS analysis when a hole transport layer containing NiOx is not subjected to an oxidation treatment. [Diagram 5] 1 is a graph showing the results of UPS analysis when a hole transport layer containing NiOx is subjected to an oxidation treatment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] The present invention will be described in detail below with reference to the drawings. The terms and words used in the specification and claims should not be limited to their ordinary or dictionary meanings, but should be interpreted as meanings and concepts that correspond to the technical ideas of the present invention, based on the principle that the inventor can appropriately define the concepts of terms in order to best describe his / her invention.

[0023] Therefore, it should be understood that the configurations described in this specification are merely the most preferred embodiment of the present invention and do not represent any of the technical ideas of the present invention, and therefore, at the time of this application, there are various equivalents and modifications that can replace them.

[0024] 2 is a diagram showing a laminate in which a substrate layer, a first electrode layer, and a hole transport layer are laminated according to the present invention. A method for manufacturing a perovskite solar cell according to the present invention will be described with reference to FIG. 2 as follows.

[0025] First, the metal oxide is oxidized by a) treating the hole transport layer 30 of a laminate in which a substrate layer 10, a first electrode layer 20, and a hole transport layer (HTL) 30 containing a metal oxide are sequentially stacked, and the hole transport layer 30 is treated with an oxidizing agent, b) with ultraviolet light and ozone, c) with oxygen plasma, or d) with nitrogen dioxide gas (step S10).

[0026] In this manner, the metal oxide contained in the hole transport layer 30 is oxidized through the above-mentioned method, such as treating with an oxidizing agent, without subjecting the hole transport layer 30 to a high-temperature heat treatment of 200° C. or more, thereby improving the hole mobility or hole extraction rate of the hole transport layer 30 without damaging the substrate layer 10 or the first electrode layer 20.

[0027] In this case, the oxidizing agent may be any material that can oxidize a metal oxide to improve metal vacancies contained in the hole transport layer or increase the oxidation number of a metal ion. Specifically, H2O2, HNO3, H2SO4, KNO3, etc. may be used.

[0028] Here, step S1 may include treating the hole transport layer 30 with a solution containing the oxidant to oxidize the metal oxide, and then removing the solvent contained in the solution.

[0029] In this case, a solution containing the oxidant may be spin-coated on the upper surface of the hole transport layer 30, or a solution process such as dip coating in which the laminate is immersed in the solution may be performed, and then the metal oxide may be oxidized and the solvent may be removed by evaporating.

[0030] The solvent is a volatile solvent to facilitate subsequent evaporation, and more specifically, may be, but is not limited to, deionized water, ethyl ether, acetone, ethanol, methanol, alcohols including isopropyl alcohol, etc. During the evaporation of the solvent, heat may be applied at a temperature of 150° C. or less to avoid damaging the perovskite.

[0031] The ultraviolet light and ozone treatment according to the present invention can oxidize metal oxides by performing the treatment for a minimum of 5 minutes or more.

[0032] Moreover, the oxygen plasma treatment of the present invention is a low-temperature oxygen plasma treatment in which the temperature is maintained below 200°C.

[0033] The nitrogen dioxide gas treatment of the present invention oxidizes the metal oxide by flowing dry air containing nitrogen dioxide onto the upper surface of the hole transport layer 30. At this time, the concentration of nitrogen dioxide in the dry air is 5 to 1,000 ppm, and the temperature is maintained at 25 to 35°C.

[0034] In the step of oxidizing the metal oxide, only the surface of the hole transport layer 30 may be oxidized, or the entire hole transport layer 30 may be oxidized.

[0035] Meanwhile, the substrate layer 10 may include a transparent material that transmits light. Also, the substrate layer 10 may include a material that selectively transmits light of a desired wavelength. The substrate layer 10 may include, for example, silicon oxide, aluminum oxide, TCO (Transparent Conductive Oxide) such as ITO (Indium Tin Oxide) and FTO (Fluorine Tin Oxide), glass, quartz, or a polymer, and for example, the polymer may include at least one of polyimide, polyethylenenaphthalate (PEN), polyethyleneterephthalate (PET), polymethylmethacrylate (PMMA), and polydimethylsiloxane (PDMS).

[0036] The substrate layer 10 may have a thickness in the range of, for example, 100 to 150 μm, for example, 125 μm. However, the material and thickness of the substrate layer 10 are not limited to those described above, and may be appropriately selected based on the technical concept of the present invention.

[0037] The first electrode layer 20 may be formed of a conductive material having light transmittance. The conductive material having light transmittance may include, for example, a transparent conductive oxide, a carbonaceous conductive material, and a metallic material. Examples of the transparent conductive oxide 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), and ZnO. Examples of the carbonaceous conductive material include graphene or carbon nanotubes, and examples of the metallic material include metal (Ag) nanowires and multi-layered metal thin films such as Au / Ag / Cu / Mg / Mo / Ti. In this specification, the term "transparent" refers to transmitting light to a certain degree or more, and is not necessarily interpreted as meaning completely transparent. The above-mentioned materials are not necessarily limited to the above-mentioned examples, and may be formed of various materials, and the structure may be variously modified, such as a single layer or a multi-layer.

[0038] In this case, the first electrode layer 20 may be formed by being laminated on the substrate layer 10 or may be formed integrally with the substrate layer 10 .

[0039] A hole transport layer 30 is laminated on the first electrode layer 20, and serves to transfer holes generated from the perovskite layer 40 to the first electrode layer 20. The hole transport layer 30 may include at least one metal oxide selected from the group consisting of tungsten oxide (WOx), molybdenum oxide (MoOx), vanadium oxide (VO5), nickel oxide (NiOx), and mixtures thereof. In addition, the hole transport layer 30 may include at least one selected from the group consisting of a monomolecular hole transport material and a polymer hole transport material, but is not limited thereto, and any material used in the industry may be used without limitation. For example, the monomolecular hole transport material may be spiro-MeOTAD [2,2',7,7'-tetrakis(N,Np-dimethoxy-phenylamino)-9,9'-spirobifluorene], and the polymer hole transport material may be P3HT [poly(3-hexylthiophene)], PTAA (polytriarylamine), poly(3,4-ethylenedioxythiophene) or polystyrene sulfonate (PEDOT:PSS), but is not limited thereto.

[0040] In addition, the hole transport layer 30 further includes a doping material, and the doping material may be a dopant 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.

[0041] The hole transport layer 30 is formed by applying a precursor solution for the hole transport layer on the first electrode layer and drying it. Before applying the precursor solution, the first electrode layer is subjected to a UV-ozone treatment to lower the work function of the first electrode layer 20, remove surface impurities, and perform a hydrophilic treatment. The precursor solution can be applied by a method such as spin coating, but is not limited thereto. The formed hole transport layer 30 has a thickness of 10 to 500 nm.

[0042] In this case, the metal oxide of the hole transport layer 30 is preferably NiOx, which has the advantage of having high hole mobility within the material compared to other organic hole transporters or other metal oxides.

[0043] Meanwhile, Fig. 3 is a conceptual diagram showing that Ni vacancies in the hole transport layer 30 are improved through an oxidizing agent treatment according to an embodiment of the present invention. Referring to Fig. 3, in the above (step S1), the NiOx is oxidized to improve the Ni vacancies in the hole transport layer 30. And, the NiOx is oxidized to improve the Ni vacancies in the hole transport layer 30. 2+ Part of Ni 3+ In this way, the Ni vacancies increase, or the Ni 2+ Part of Ni 3+ Oxidation of the hole transport layer 30 increases hole mobility, reduces resistance, and improves hole extraction in the hole transport layer 30 .

[0044] Here, the Ni 3+ and the Ni content 2+ and Ni 3+ The ratio of the total content is 0.6 or less, specifically 0.3 or less. In this case, if the ratio of the content exceeds 0.6, that is, Ni 3+ If the content is too high, the optical transmittance decreases. 3+ As the ratio of Ni increases, the valence band maximum (VBM) of the hole transport layer 30 shifts downward. 3+ and the Ni content 2+ and Ni 3+ When the ratio of the total content of Ni is about 0.6, more preferably about 0.3, the energy matching with the perovskite layer occurs well, and efficient charge extraction can occur. 3+If the content is too high and the VBM (work function) drops too much, a mismatch in energy level alignment occurs at the interface with the perovskite, which causes a problem of preventing hole extraction at the interface.

[0045] FIG. 4 is a graph showing the UPS analysis results when the NiOx-containing hole transport layer is not oxidized, and FIG. 5 is a graph showing the UPS analysis results when the NiOx-containing hole transport layer is oxidized. Table 1 below shows the work function and valence band edge values ​​for each of the above cases.

[0046] [Table 1]

[0047] After oxidation treatment of NiOx, 3+ It can be seen that as the ratio of increases, the value of the work function increases and approaches the valence band edge value, which means that there is an effect similar to p-type doping.

[0048] 1) NiOx (w / o treatment) work function:21.22eV(He|UPS spectra)-16.56eV=4.66eV valence band edge:4.66(work function)eV+0.95eV=5.61eV

[0049] 2) In the case of NiOx (w / treatment), work function:21.22eV(He|UPS spectra)-16.06eV=5.16eV valence band edge:5.16(work function)eV+0.53eV=5.69eV

[0050] Subsequently, a perovskite layer 40, an electron transport layer 50 and a second electrode layer 60 are sequentially laminated on the hole transport layer 30 of the laminate (step S2).

[0051] In the perovskite solar cell 100 according to the present invention, a perovskite compound is adopted as a photoactive material that absorbs solar light and generates photoelectron-photohole pairs. Perovskite has a direct band gap and a light absorption coefficient of 1.5×10 at 550 nm. 4 cm -1 It has the advantages of being highly uniform, having excellent charge transport properties, and being highly resistant to defects.

[0052] In addition, perovskite compounds have the advantage that they can form a light absorber that constitutes a photoactive layer through a very simple, easy, and low-cost process of coating and drying a solution. They spontaneously crystallize when the coated solution dries, making it possible to form a light absorber with coarse crystal grains, and they have excellent conductivity for both electrons and holes.

[0053] Such a perovskite compound is represented by the structure of Chemical Formula 1 below. ABX3 (wherein A is a monovalent organic ammonium cation or metal cation, B is a divalent metal cation, and X is a halogen anion).

[0054] Perovskite compounds include, for example, CH3NH3PbI3, CH3NH3PbI x Cl 3-x , MAPbI3, 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 , (CH3NH3)(HC(NH2)2) 1-y PbCl x Br 3-x (0≦x, y≦1). Compounds in which A in ABX3 is partially doped with Cs are also used.

[0055] The electron transport layer 50 is located on the perovskite layer 40 and functions to easily transport electrons generated from the perovskite layer 40 to the second electrode layer 60. The electron transport layer 50 includes a metal oxide, such as Ti oxide, Zn oxide, In oxide, Sn oxide, W oxide, Nb oxide, Mo oxide, Mg oxide, Zr oxide, Sr oxide, Yr oxide, La oxide, V oxide, Al oxide, Y oxide, Sc oxide, Sm oxide, Ga oxide, SrTi oxide, etc. The electron transport layer 50 according to the present invention may include TiO2, SnO2, WO3, or TiSrO3, etc., having a compact structure. The electron transport layer 50 may further include an n-type or p-type dopant as necessary.

[0056] In addition to the above-mentioned interlayer structures and / or materials, various layer structures and materials constituting the perovskite solar cell 100 may be applied to the hole transport layer 30 / perovskite layer 40 / electron transport layer 50, and the hole transport layer 30 and the electron transport layer 50 may be formed at different positions.

[0057] The second electrode layer 60 may be formed of a conductive material having light transmittance. The conductive material having light transmittance may include, for example, a transparent conductive oxide, a carbonaceous conductive material, and a metallic material. Examples of the transparent conductive oxide 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), and ZnO. Examples of the carbonaceous conductive material include graphene or carbon nanotubes, and examples of the metallic material include metal (Ag) nanowires and multi-layered metal thin films such as Au / Ag / Cu / Mg / Mo / Ti. In this specification, the term "transparent" refers to transmitting light to a certain degree or more, and is not necessarily interpreted as meaning completely transparent. The above-mentioned materials are not necessarily limited to the above-mentioned examples, and may be formed of various materials, and the structure may be variously modified, such as a single layer or a multi-layer.

[0058] Meanwhile, although not shown, a bus electrode (not shown) may be further disposed on the second electrode layer 60 to reduce the resistance of the second electrode layer 60 and to further facilitate the transfer of charges. The bus electrode may be formed of Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, and / or a compound thereof.

[0059] Meanwhile, the embodiments of the present invention disclosed in this specification and the drawings are specific examples presented to easily explain the technical contents of the present invention and to facilitate understanding of the present invention, and are not intended to limit the scope of the present invention. It will be obvious to those skilled in the art that other modifications based on the technical concept of the present invention can be implemented in addition to the embodiments disclosed herein.

Claims

1. (Step S1) Oxidizing the metal oxide by performing an oxygen plasma treatment or a nitrogen dioxide gas treatment on the hole transport layer of a laminate in which a substrate layer, a first electrode layer, and a hole transport layer (HTL) including a metal oxide are sequentially laminated, without performing a high-temperature heat treatment of 200° C. or more; (Step S2) sequentially stacking a perovskite layer, an electron transport layer, and a second electrode layer on the hole transport layer of the stack; Including, In the step S1, the metal oxide NiOx is oxidized to Ni ３＋ In order to increase the ratio of Ni and prevent the decrease in light transmittance and the mismatch of the energy level alignment, ２＋ and Ni ３＋ Ni relative to the total content ３＋ The ratio of the contents of is 0.6 or less, The hole transport layer contains Ni vacancies, Ni ２＋ and Ni ３＋ A method for producing a perovskite solar cell, comprising:

2. 2. The method for producing a perovskite solar cell according to claim 1, wherein in the step S1, the NiOx is oxidized to improve Ni vacancies in the hole transport layer.

3. In the step S1, the NiOx is oxidized to remove the Ni contained in the hole transport layer. ２＋ Part of Ni ３＋ The method for producing a perovskite solar cell according to claim 1, wherein the

4. The first electrode layer and the second electrode layer are each independently made of ITO (indium tin oxide), ICO (indium cerium oxide), IWO (indium tungsten oxide), ZITO (zinc indium tin oxide), ZIO (zinc indium oxide), ZTO (zinc tin oxide), GITO (gallium indium tin oxide), GIO (gallium indium oxide), GZO (gallium zinc oxide), AZO (aluminum doped zinc), 2. The method for producing a perovskite solar cell according to claim 1, wherein the perovskite solar cell comprises at least one selected from the group consisting of fluorine tin oxide (FTO), fluorine tin oxide (FTO), and ZnO.

5. 2. The method for producing a perovskite solar cell according to claim 1, wherein the electron transport layer comprises any one or more selected from the group consisting of Ti oxide, Zn oxide, In oxide, Sn oxide, W oxide, Nb oxide, Mo oxide, Mg oxide, Zr oxide, Sr oxide, Yr oxide, La oxide, V oxide, Al oxide, Y oxide, Sc oxide, Sm oxide, Ga oxide, and SrTi oxide.

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