A photoactive layer containing a perovskite compound with a two-dimensional or quasi-two-dimensional crystal structure and a perovskite photoelectric device including the same

Abstract

The present disclosure relates to a photoactive layer for a perovskite photovoltaic device and a perovskite photovoltaic device comprising the same, the photoactive layer comprising: a first layer comprising a first perovskite compound having a three-dimensional crystal structure; a second layer comprising a second perovskite compound having a two-dimensional or quasi-two-dimensional crystal structure located on at least one surface of the first layer; and an organic ammonium halide compound dispersed in at least one of the first layer and the second layer.

Description

Technology Field

[0001] The present disclosure relates to a photoactive layer containing a perovskite compound having a two-dimensional or quasi-two-dimensional crystal structure and a perovskite photovoltaic device comprising the same. Background Technology

[0002] Recently, perovskite compounds, possessing advantages such as high light absorption, high external quantum efficiency (EQE), rapid charge transfer rates, and solution processability, are garnering attention as key materials for next-generation optoelectronic devices. Conventionally, extensive research on perovskite materials has focused on solar cells; they possess efficiencies comparable to silicon solar cells, yet offer excellent commercial viability due to very low material costs and the possibility of low-temperature or low-cost solution processing, leading to imminent commercialization.

[0003] Organometallic halides of a perovskite structure, referred to as organic-inorganic perovskite compounds, contain an organic cation (A), a metal cation (M), and a halogen anion (X), and are represented by an AMX3 structure having a three-dimensional crystal structure. Perovskite compounds having a three-dimensional crystal structure still have low stability against light, heat, and moisture, and there is a need to improve charge transfer efficiency.

[0004] To address this, photovoltaic devices containing mixed cation perovskite compounds using two or more monovalent organic cations of perovskite compounds have been developed. For example, photovoltaic devices containing mixed cation perovskite compounds including formamidinium (FA) and cesium (Cs) have been reported to exhibit high stability and photoelectric conversion efficiency. However, these mixed cation perovskite photovoltaic devices exhibit unstable characteristics due to high crystallization difficulties, so improvements are needed. The problem to be solved

[0005] The purpose of the present disclosure is to solve the problems of the prior art described above by providing a photoactive layer having excellent crystallinity and improved interface and surface defects, and a perovskite photovoltaic device comprising the same.

[0006] Another object of the present disclosure is to provide a photoactive layer having high photostability and high stability in air, and a perovskite photovoltaic device comprising the same. means of solving the problem

[0007] A photoactive layer for a perovskite photovoltaic device according to the present disclosure comprises: a first layer comprising a first perovskite compound having a three-dimensional crystal structure; a second layer located on at least one surface of the first layer and comprising a second perovskite compound having a two-dimensional or quasi-two-dimensional crystal structure; and an organic ammonium halide represented by the following chemical formula 1, dispersed in at least one of the first layer and the second layer.

[0008] [Chemical Formula 1]

[0009] RNH3 + X -

[0010] (In the above chemical formula 1,

[0011] R is a substituted or unsubstituted C6-C30 aryl group; a C7-C40 arylalkyl group; a C7-C40 arylalkenyl group; or a C3-C30 cycloalkyl group; and

[0012] X is F, Cl, Br, or I)

[0013] In one example, the second perovskite compound may be represented by the following chemical formula 2 or chemical formula 3.

[0014] [Chemical Formula 2]

[0015] A 2n B n X 3n+1

[0016] [Chemical Formula 3]

[0017] A 2m-1B m X 3m+1

[0018] (In the above Chemical Formulas 2 and 3,

[0019] A are each independently a monovalent organic ammonium cation; a monovalent amidinium cation; Li + ; Na + ; K + ; Rb + ; Cs + ; Fr + ; Cu(I) + ; Ag(I) + ; and Au(I) + It is a monovalent cation comprising one or more selected from ; and

[0020] B are each independently divalent metal cations, and

[0021] X are each independently F - , I - , Br - , Cl - or a halogen anion comprising a combination thereof, and

[0022] n is a real number from 0 to 5, and

[0023] m is a real number between 2 and 10)

[0024] In one example, the organic ammonium halide compound may include propyl phenyl ammonium chloride (PPACl).

[0025] In one example, in the XRD spectrum of the photoactive layer for the perovskite photovoltaic device, the full width half maximum (FWHM) of the first peak appearing at a diffraction angle of 2θ = 14˚±0.5˚ may be 0.14˚ or less.

[0026] In one example, the average crystal size of the second perovskite compound may be 450 to 600 nm.

[0027] In one example, in the XRD spectrum of the photoactive layer for the perovskite photovoltaic device, the intensities of the first peak appearing at a diffraction angle of 2θ = 14˚±0.5˚ and the second peak appearing at a diffraction angle of 2θ = 28˚±1.0˚ are each independently 1 x 10 4 It may be more than cps.

[0028] In one example, the first perovskite compound can be represented by the following chemical formula 4.

[0029] [Chemical Formula 4]

[0030] ABX3

[0031] (In the above chemical formula 4,

[0032] A is a monovalent organic ammonium cation; a monovalent amidinium cation; Li + ; Na + ; K + ; Rb + ; Cs + ; Fr + ; Cu(I) + ; Ag(I) + ; and Au(I) + It is a monovalent cation comprising one or more selected from ; and

[0033] B is a divalent metal cation, and

[0034] X is F - , I - , Br - , Cl - or is a halogen anion containing a combination thereof)

[0035] In one example, at least one of the first perovskite compound and the second perovskite compound is a monovalent organic ammonium ion (RNH3) contained in the organic ammonium halide compound. + It may include ).

[0036] In one example, the second perovskite compound may have a crystal structure of 1 to 10 layers.

[0037] In one example, the second perovskite compound may have a quasi-two-dimensional crystal structure.

[0038] In one example, the second perovskite compound may satisfy the following chemical formula 5.

[0039] [Chemical Formula 5]

[0040] (RNH3)2(Cs x FA 1-x ) m-1 Pb m I 3m+1

[0041] (In the above chemical formula 5,

[0042] R is a substituted or unsubstituted C6-C30 aryl group; a C7-C40 arylalkyl group; a C7-C40 arylalkenyl group; or a C3-C30 cycloalkyl group; and

[0043] m is a real number between 2 and 10)

[0044] A perovskite photovoltaic device according to the present disclosure comprises a photoactive layer for the perovskite photovoltaic device described above.

[0045] In one example, the apparatus may further include an electron transport layer located on one side of the photoactive layer for the perovskite photovoltaic device; a hole transport layer located on the other side of the photoactive layer for the perovskite photovoltaic device; a first electrode located on one side of the electron transport layer; and a second electrode located on one side of the hole transport layer.

[0046] In one example, the hole transport layer may be located on the surface in contact with the second layer of the photoactive layer for the perovskite photovoltaic device.

[0047] In one example, the power conversion efficiency (PCE) can be 19% or more. Effects of the invention

[0048] The photoactive layer of the present disclosure and the perovskite photovoltaic device including the same have excellent crystallinity, and interface and surface defects can be improved.

[0049] In addition, the photoactive layer of the present disclosure and the perovskite photovoltaic device including the same have the advantage of having high photostability and high stability in air. Brief explanation of the drawing

[0050] FIG. 1 is a schematic diagram illustrating the configuration of a perovskite photovoltaic device according to one embodiment of the present disclosure. Figure 2a is the XRD analysis spectrum of the photoactive layer according to Example 1 (PPACl), Comparative Example 1 (Control), and Comparative Example 2 (MACl). FIG. 2b is a graph showing the intensity of the first peak assigned to the (110) plane and the full width at half maximum (FWHM) of the first peak as a result of XRD analysis of the photoactive layer according to Example 1 (PPACl), Comparative Example 1 (Control), and Comparative Example 2 (MACl). FIG. 2c is a histogram showing scanning electron microscope images and crystal size distributions of the surface of the photoactive layer according to Example 1 (PPACl), Comparative Example 1 (Control), and Comparative Example 2 (MACl). Figure 3 is a current density-voltage curve (JV curve) of a perovskite photovoltaic device according to Example 2 (Target) and Comparative Example 4 (Control). Figure 4 is a graph showing the measured stabilized power outputs (SPO) of perovskite photovoltaic devices according to Example 2 (Target) and Comparative Example 4 (Control). Specific details for implementing the invention

[0051] The terms used in this specification have been selected to be as widely used as possible, taking into account the function of this disclosure; however, these terms may vary depending on the intent of those skilled in the relevant field, case law, the emergence of new technologies, etc. Unless otherwise defined, technical and scientific terms used may have the meaning commonly understood by those skilled in the art to which this invention pertains.

[0052] In this specification and the appended claims, terms such as “comprising” or “having” mean that the features or components described in the specification exist, and unless specifically limited, do not preclude the possibility that one or more other features or components may be added.

[0053] In this specification and the appended claims, when a part such as a film (layer), region, or component is described as being on or above another part, it includes not only cases where it is directly above in contact with the other part, but also cases where another film (layer), other region, or other component is interposed therein.

[0054] In this specification and the appended claims, terms such as "first," "second," etc. are used not in a limiting sense, but for the purpose of distinguishing one component from another.

[0055] Singular expressions used in this specification and the appended claims include plural expressions unless the context clearly indicates that they are singular. Additionally, plural expressions include singular expressions unless the context clearly indicates that they are plural.

[0056] Additionally, numerical ranges used herein include lower and upper limits and all values ​​within the range, increments logically derived from the form and width of the defined range, all of which are limited values, and all possible combinations of upper and lower limits of numerical ranges defined in different forms. Unless otherwise specifically defined in the specification of this disclosure, values ​​outside the numerical range that may occur due to experimental error or rounding of values ​​are also included in the defined numerical range.

[0057] Terms such as "approximately" used in this specification and the appended claims are used to encompass tolerances when tolerances exist.

[0058] The prefix 'Cx-Cy' used in this specification (where x and y are natural numbers) refers to the number of carbon atoms present in the main backbone of the corresponding functional group.

[0059] The term 'substitution' in this specification means being substituted with one or more substituents selected from the group comprising deuterium; halogen; alkyl group; alkenyl group; cycloalkyl group; and aryl group.

[0060] The term 'alkyl group' in this specification refers to a straight-chain or branched-chain saturated hydrocarbon monovalent group composed only of carbon and hydrogen atoms, specifically including, but not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, t-butyl, n-pentyl, n-hexyl, etc.

[0061] The term 'alkenyl group' in this specification refers to a straight-chain or branched-chain unsaturated hydrocarbon group comprising one or more carbon-carbon double bonds, specifically including, but not limited to, vinyl, propene, butenyl, pentenyl, hexenyl, butadienyl, pentadienyl, hexadienyl, hexatrienyl, cyclopentenyl, cyclohexadienyl, cyclopentadienyl, cyclohexadienyl, etc.

[0062] The term 'aryl group' in this specification refers to a monovalent group derived from an aromatic hydrocarbon ring by the removal of one hydrogen, comprising a single or fused ring system having, suitably, 4 to 7, preferably 5 or 6 ring atoms in each ring, and includes forms in which multiple aryls are bonded. Examples include, but are not limited to, phenyl, naphthyl, biphenyl, terphenyl, anthryl, indenyl, fluorenyl, phenanthryl, triphenylenyl, pyrenyl, perylenyl, chrysenyl, naphthacenyl, fluoranthenyl, etc.

[0063] The term 'arylalkyl group' in this specification refers to a group in which at least one of the hydrogen atoms of an alkyl group is substituted with an aryl group, and the aryl group and the alkyl group are the same as those described above.

[0064] The term 'aryl alkenyl group' in this specification refers to a group in which at least one of the hydrogen atoms of an alkenyl group is substituted with an aryl group, and the aryl group and the alkenyl group are as described above.

[0065] The term 'cycloalkyl group' in this specification means a monovalent group derived by the removal of one hydrogen from a hydrocarbon ring in which two or more carbon atoms are single-bonded, and includes, but is not limited to, cyclopropyl, cyclobutyl, cyclopentyl, 3-methylcyclopentyl, 2,3-dimethylcyclopentyl, cyclohexyl, 3-methylcyclohexyl, 4-methylcyclohexyl, 2,3-dimethylcyclohexyl, 3,4,5-trimethylcyclohexyl, 4-tert-butylcyclohexyl, cycloheptyl, cyclooctyl, adamantyl group, bicyclo[2.2.1]heptyl group, bicyclo[2.2.1]octyl group, norbornyl group.

[0066] The term 'halogen' in this specification means an atom of fluorine, chlorine, bromine, or iodine.

[0067] The term 'perovskite compound having a two-dimensional crystal structure' in this specification may mean a stacked structure in which one perovskite unit cell layer is separated from other unit cell layers by an insulating layer such as an organic cation.

[0068] The term 'perovskite compound having a quasi-two-dimensional crystal structure' in this specification may refer to a perovskite structure in which n consecutive perovskite unit cell layers are stacked and separated from other unit cell layers by an insulating layer such as a large organic cation in a regular manner. For example, a perovskite compound having a quasi-two-dimensional crystal structure with n=2 may refer to a perovskite structure in which two consecutive perovskite unit cell layers are stacked and separated from other unit cell layers by an organic cation.

[0069] Hereinafter, a photoactive layer for a perovskite photovoltaic device and a perovskite photovoltaic device including the same according to the present disclosure will be described in detail.

[0070] A photoactive layer for a perovskite photovoltaic device according to the present disclosure comprises: a first layer comprising a first perovskite compound having a three-dimensional crystal structure; a second layer located on at least one surface of the first layer and comprising a second perovskite compound having a two-dimensional or quasi-two-dimensional crystal structure; and an organic ammonium halide represented by the following chemical formula 1, dispersed in at least one of the first layer and the second layer.

[0071] [Chemical Formula 1]

[0072] RNH3 + X -

[0073] (In the above chemical formula 1,

[0074] R is a substituted or unsubstituted C6-C30 aryl group; a C7-C40 arylalkyl group; a C7-C40 arylalkenyl group; or a C3-C30 cycloalkyl group; and

[0075] X is a halogen element including F, Cl, Br, I, or a combination thereof)

[0076] The photoactive layer of the present disclosure comprising the aforementioned composition can improve the crystallinity of the first perovskite compound and the second perovskite compound and enhance the stability of the crystal structure. By improving the crystallinity of the perovskite compounds and thereby improving surface defects of the first and second layers, the energy levels at the interface between each layer are aligned, thus allowing for effective control of the flow of charge carriers. Accordingly, the thermal stability and stability in air, as well as the photoelectric conversion efficiency of the perovskite photovoltaic device comprising the photoactive layer of the present disclosure, can be significantly improved.

[0077] The above-mentioned organic ammonium halide compound is dispersed in at least one of the first layer and the second layer to stabilize the crystal structure of the first perovskite compound and the second perovskite compound and improve crystallinity. Accordingly, by including a perovskite compound having a uniform and excellent crystal structure throughout the first and second layers, interfacial defects between each layer can be mitigated.

[0078] Specifically, in the above formula 1, R may be a substituted or unsubstituted C6-C30 aryl group; a C7-C40 arylalkyl group; a C7-C40 arylalkenyl group; or a C3-C30 cycloalkyl group. Specifically, R may be a substituted or unsubstituted C6-C24 aryl group; a C7-C30 arylalkyl group; a C7-C30 arylalkenyl group; or a C3-C25 cycloalkyl group. More specifically, R may be a substituted or unsubstituted C6-C18 aryl group; a C7-C20 arylalkyl group; a C7-C20 arylalkenyl group; or a C3-C20 cycloalkyl group.

[0079] When the organic ammonium halide contains cyclic hydrocarbons, preferably aromatic hydrocarbons, it can efficiently separate and transport charge carriers generated in the photoactive layer. Although not limited to this interpretation, aromatic hydrocarbons contain delocalized electrons, thereby improving electrical conductivity, which enhances charge carrier mobility, and effectively controls the flow of charge carriers.

[0080] More specifically, the above R may be a C7-C40, C7-C20, or C8-C10 arylalkyl group, and preferably, when the organic ammonium halide compound includes propyl phenyl ammonium chloride (PPACl) represented by the following chemical formula 1-1, the above-mentioned effect can be maximized, which is advantageous.

[0081] [Chemical Formula 1-1]

[0082]

[0083] A photoactive layer for a perovskite photovoltaic device according to one embodiment of the present disclosure comprises a first layer comprising a first perovskite compound having a three-dimensional crystal structure and a second layer comprising a second perovskite compound having a two-dimensional or quasi-two-dimensional crystal structure located on at least one surface of the first layer, thereby providing a high-quality thin film with improved crystallinity and reduced defects compared to a conventional photoactive layer comprising a single layer of perovskite compound having a two-dimensional, quasi-two-dimensional, or three-dimensional crystal structure, i.e., a single-dimensional crystal structure.

[0084] In one example, the second perovskite compound may be represented by the following chemical formula 2 or chemical formula 3, and the first perovskite compound may be represented by the following chemical formula 4.

[0085] [Chemical Formula 2]

[0086] A 2n B n X 3n+1

[0087] [Chemical Formula 3]

[0088] A 2m-1 B m X 3m+1

[0089] [Chemical Formula 4]

[0090] ABX3

[0091] (In the above chemical formulas 2 to 4,

[0092] A are each independently a monovalent organic ammonium cation; a monovalent amidinium cation; Li + ; Na + ; K + ; Rb + ; Cs + ; Fr + ; Cu(I) + ; Ag(I) + ; and Au(I) + It is a monovalent cation comprising one or more selected from ; and

[0093] B are each independently divalent metal cations, and

[0094] X are each independently F - , I - , Br - , Cl - or a halogen anion comprising a combination thereof, and

[0095] n is a real number from 0 to 5, and

[0096] m is a real number between 2 and 10)

[0097] The above A is a monovalent cation, specifically a monovalent amidinium group cation; a monovalent organic ammonium group cation; Li + ; Na + ; K + ; Rb + ; Cs + ; Fr + ; Cu(I) + ; Ag(I) + ; and Au(I) +One or more selected from ; may be included, preferably two or more.

[0098] As an indefinite example, the amidinium-based ion is formamidinium (formamidinium, NH2CH=NH2 + ) ion, acetamidinium (acetamidinium, NH2C(CH3)=NH2 + ) or Guamidinium (Guamidinium, NH2C(NH2)=NH2 + Examples include ) and organic ammonium ions may include C1-C24 alkyl ammonium ions, C3-C20 cycloalkyl ammonium ions, C6-C30 aryl ammonium ions, C7-C40 arylalkyl ammonium ions or C7-C40 arylalkenyl ammonium ions.

[0099] In one embodiment, the organic ammonium ion is a monovalent organic ammonium ion (RNH3) contained in the organic ammonium halide compound. + ) It may be. That is, the first perovskite compound and the second perovskite compound are monovalent organic ammonium ions (RNH3) contained in the organic ammonium halide compound. + It may include ). Accordingly, the perovskite crystallinity is improved to resolve structural instability, surface defects between the first layer and the second layer are improved, and there is an interfacial energy level alignment effect.

[0100] Preferably, A includes two or more types of monovalent cations to improve the photoelectric conversion efficiency of the photovoltaic device. In this case, A is A' 1-x A'' x (A'' is the aforementioned monovalent organic ammonium ion, A' is the aforementioned amidinium-based ion or monovalent metal cation, and x is 0 <x<1인 실수, 좋게는 0.05≤x≤ 0.3인 실수)를 만족할 수 있다.

[0101] More preferably, A may include three or more types of monovalent organic cations. In this case, A is A'A'' 1-x A'''x (A' and A''' are each independently the aforementioned monovalent organic ammonium ions, A'' is the aforementioned amidinium-based ion or monovalent metal cation, and x is 0 <x<1인 실수, 좋게는 0.05≤x≤ 0.3인 실수)를 만족할 수 있다. 이때, 상기 A'는 상기 유기 할로겐화 암모늄 화합물로부터 기인한 1가 유기 암모늄 이온(RNH3 + , R can be as described above.

[0102] When a monovalent organic ammonium ion contained in a second perovskite compound and an organic ammonium halide compound combines, the crystallinity of a mixed cation perovskite compound containing two or more monovalent cations is improved, and structural instability is improved, thereby improving the performance of a photovoltaic device containing the same.

[0103] The above B is a divalent metal cation, for example, Cu 2+ , Ni 2+ , Co 2+ , Fe 2+ , Mn 2+ , Cr 2+ , Pd 2+ , Cd 2+ , Ge 2+ , Sn 2+ , Pb 2+ and Yb 2+ It may include one or more types selected from, but the present disclosure is not limited thereto.

[0104] The above n and m represent the number of octahedral layers in the perovskite compound, and the second perovskite compound may have a crystal structure of 1 to 10 layers or 2 to 10 layers. Specifically, the second perovskite compound may have a 2D perovskite crystal structure of 1 layer (n=1) or a quasi-2D perovskite crystal structure of 2 to 10 layers (2≤m≤10).

[0105] Preferably, the second perovskite compound may have a quasi-two-dimensional crystal structure. The second layer comprising the second perovskite compound having a quasi-two-dimensional crystal structure can significantly improve moisture stability, structural stability, thermal stability, and air stability through a synergistic effect resulting from the combination with the first layer and the organic ammonium halide compound.

[0106] In a non-limiting and specific embodiment, the second perovskite compound may be a quasi-two-dimensional perovskite compound satisfying the following chemical formula 5.

[0107] [Chemical Formula 5]

[0108] {RNH3(Cs x FA 1-x )} 2m-1 Pb m I 3m+1

[0109] (In the above chemical formula 5, R is a substituted or unsubstituted C6-C30 aryl group; a C7-C40 arylalkyl group; a C7-C40 arylalkenyl group; or a C3-C30 cycloalkyl group; and m is a real number from 2 to 10)

[0110] As mentioned above, RNH3 of Chemical Formula 5 is an organic ammonium ion (RNH3) contained in the above organic ammonium halide compound. + ) It may be. When the above chemical formula is satisfied, the effect of improving structural stability due to improved crystallinity is maximized, and the performance of the perovskite photovoltaic device can be improved.

[0111] More specifically, the second perovskite compound has the chemical formula C6H5C3H8NH3(Cs x FA 1-x ) 2n-1 Pb n I 3n+1 It may be a quasi-two-dimensional perovskite compound satisfying [condition]. As mentioned above, C6H5C3H8NH3 is an organic ammonium ion (RNH3) contained in the above organic ammonium halide compound. +, R=C6H5C3H8) can be.

[0112] In one example, the average crystal size of the second perovskite compound may be 450 to 600 nm, 460 to 550 nm, or 470 to 500 nm. As the crystal size of the perovskite compound increases to the above numerical range and crystallinity is improved, interface defects between the first layer and the second layer, and further between the photoactive layer and the charge transport layer, are mitigated, thereby further enhancing the charge transport capacity and the effect of reducing charge carrier recombination.

[0113] In the XRD spectrum of the photoactive layer for the perovskite photovoltaic device, the full width half maximum (FWHM) of the first peak appearing at a diffraction angle of 2θ = 14˚±0.5˚ may be 0.14˚ or less, 0.13˚ or less, 0.12˚ or less, 0.11˚ or less, 0.10˚ or less, or 0.09˚ or less, and as a non-limiting example, may be 0.01˚ or more, 0.02˚ or more, 0.03˚ or more, 0.04˚ or more, or 0.05˚ or more, or may be a range between any two of the above values.

[0114] A photoactive layer according to one embodiment of the present disclosure can provide a photoactive layer having significant crystallinity and stability as the crystal structure of the first perovskite compound and the second perovskite compound is stabilized, so that the first peak corresponding to the (110) plane has a very narrow and strong intensity with a half-width of the above range.

[0115] In addition, in the XRD spectrum of the photoactive layer for the perovskite photovoltaic device, the intensities of the first peak appearing at a diffraction angle of 2θ = 14˚±0.5˚ and the second peak appearing at a diffraction angle of 2θ = 28˚±1.0˚ are each independently 1 x 10 4 cps or higher, 2 x 10 4 cps or higher, 3 x 10 4 cps or higher or 4 x 104 May be more than cps, and is not limited to, 1 x 10 7 cps or less, 1 x 10 6 cps or less, 1 x 10 5 cps or less or 10 x 10 4 It may be less than cps and may be a range between any two of the above values. When the intensity of the first peak and the second peak has the above range, the film quality of the first layer and the second layer can be improved with high crystallinity.

[0116] In one embodiment, the method for manufacturing the above-described perovskite photoactive layer may include: (S1) a step of manufacturing a first material layer by applying and heat-treating a mixed precursor solution in which an organic ammonium halide compound represented by Chemical Formula 1 is added to a perovskite precursor solution; and (S2) a step of manufacturing a photoactive layer by applying and heat-treating a passivating agent on the first material layer.

[0117] A mixed precursor solution containing the above perovskite precursor solution and an organic ammonium halide compound can be applied to a substrate and heat-treated to grow a first layer containing a perovskite compound having a three-dimensional crystal structure, and at the same time, a perovskite compound having a two-dimensional or quasi-two-dimensional crystal structure can spontaneously grow on the first layer to form a second layer. The photoactive layer having such a structure allows the second layer to protect the three-dimensional perovskite crystal of the first layer, and with a high charge transfer rate, the perovskite photovoltaic device can have high photovoltaic conversion efficiency and high stability.

[0118] At this time, the organic ammonium halide compound, the first layer, the second layer, the perovskite compound having a three-dimensional crystal structure, and the perovskite compound having a two-dimensional or quasi-two-dimensional crystal structure are the same as those described above, so a detailed description is omitted.

[0119] According to one embodiment, a compound comprising a cation satisfying Formula 1 and a halogen ion combined, i.e., a perovskite intermediate layer precursor, may be mixed into the perovskite precursor solution. At this time, the cation satisfying Formula 1 may exhibit a significant effect as described above. In addition, the halogen ion contained in the perovskite intermediate layer precursor may be located at a defect in the perovskite photoactive layer, i.e., a three-dimensional perovskite crystal, to heal the defect in the three-dimensional perovskite crystal and thereby exhibit higher crystallinity.

[0120] The above perovskite precursor solution may contain halides of monovalent amidinium group cations, halides of monovalent alkylammonium group cations, cesium halides, metal halides (of divalent metals), and a solvent.

[0121] A mixed precursor solution prepared by adding and stirring an organic ammonium halide compound to a perovskite precursor solution is applied onto a substrate and then heat-treated so that the ions contained in the solution crystallize into a perovskite compound through spontaneous crystallization, and the perovskite precursor solution may contain monovalent amidinium cations, alkylammonium monovalent cations, inorganic cations including cesium ions and metal ions, and anions including halogen ions, to satisfy the composition of the desired perovskite compound.

[0122] For example, when preparing the above mixed precursor solution, 0.01 to 1.00 moles, 0.02 to 0.50 moles, 0.03 to 0.10 moles, or 0.04 to 0.07 moles of an organic ammonium halide compound may be added based on 1.00 moles of ions contained in the perovskite precursor solution. When added within the above ranges, the effect of improving the crystallinity of the perovskite compound is significant and is preferred, but the present disclosure is not limited thereto.

[0123] The above substrate may be an electron transport layer or a hole transport layer of a perovskite photovoltaic device described later.

[0124] The above solvent may be a polar organic solvent in which the perovskite compound dissolves and can be easily volatilized and removed upon drying. As an example, the polar organic solvent may be one or more selected from gamma-butyrolactone, formamide, N,N-dimethylformamide, diformamide, acetonitrile, tetrahydrofuran, dimethyl sulfoxide, diethylene glycol, 1-methyl-2-pyrrolidone, N,N-dimethylacetamide, acetone, α-terpineol, β-terpineol, dihydroterpineol, 2-methoxyethanol, acetylacetone, methanol, ethanol, propanol, butanol, pentanol, hexanol, ketone, methyl isobutyl ketone, etc., but the present invention is not limited by the specific material of the solvent.

[0125] In one embodiment, the crystallinity of the perovskite photoactive layer can be further improved by additionally performing a solvent-nonsolvent coating method in which a nonsolvent is applied during or immediately after the application of the mixed precursor solution (before heat treatment).

[0126] The above nonsolvent may be used without limitation as long as it is an organic solvent that does not dissolve the mixed precursor solution, and specifically, may include one or more nonpolar organic solvents selected from pentane, hexene, cyclohexene, 1,4-dioxene, benzene, toluene, triethylamine, chlorobenzene, ethylamine, ethyl ether, chloroform, ethyl acetate, acetic acid, 1,2-dichlorobenzene, tert-butyl alcohol, 2-butanol, isopropanol, and methyl ethyl ketone, but the present disclosure is not limited thereto.

[0127] In one embodiment, the heat treatment of step (S1) can be performed at a temperature of 100 to 250°C, 120 to 230°C, 140 to 200°C, or 160 to 180°C.

[0128] After step (S1), in step (S2), a photoactive layer can be manufactured by applying a passivation agent to the first material layer and heat-treating it.

[0129] In one example, the passivating agent may include a diaminobenzidine (DAB) solution. This can produce a high-quality photoactive layer by changing the surface morphology of the first material layer and mitigating surface defects.

[0130] In one embodiment, the heat treatment of step (S2) may be performed at a temperature of 50 to 200°C, 70 to 160°C, or 90 to 120°C, but the present disclosure is not limited by the heat treatment temperature.

[0131] The present disclosure includes a perovskite photovoltaic device comprising the aforementioned photoactive layer.

[0132] In describing the perovskite photovoltaic device of the present disclosure, the material, structure, shape, or size of the first perovskite compound, the second perovskite compound, the first layer, the second layer, and the organic ammonium halide compound included in the photoactive layer are identical or similar to those described above in the photoactive layer for a perovskite photovoltaic device; therefore, the perovskite photovoltaic device of the present disclosure includes all the contents described above.

[0133] In one example, referring to FIG. 1, the perovskite photovoltaic device may include: a photoactive layer for the perovskite photovoltaic device described above; an electron transport layer located on one side of the photoactive layer for the perovskite photovoltaic device; a hole transport layer located on the other side of the photoactive layer for the perovskite photovoltaic device; a first electrode located on one side of the electron transport layer; and a second electrode located on one side of the hole transport layer.

[0134] In addition, the hole transport layer may be located on a surface in contact with the second layer of the photoactive layer for the perovskite photovoltaic device to block the movement of electrons and promote the movement of holes, but the present disclosure is not limited thereto.

[0135] As described above, the photoactive layer of the present disclosure possesses high crystallinity and structural stability, thereby minimizing surface defects of the photoactive layer and improving interfacial defects between the photoactive layer and the electron transport layer and hole transport layer in contact therewith. Consequently, charge carrier recombination can be suppressed and charge mobility can be improved. Accordingly, the performance of the photoelectric device, including the photoelectric conversion efficiency, can be significantly improved. Furthermore, the structural stability of the perovskite compound included in the photoactive layer is enhanced, thereby improving the thermal stability and stability in air of the perovskite photoelectric device, which can improve its lifespan and durability.

[0136] In one embodiment, the power conversion efficiency (PCE) of the perovskite photovoltaic device can be significantly improved to 19% or more, 20% or more, or 21% or more.

[0137] The first electrode may be a conductive electrode that is ohmic-bonded to the perovskite thin film. As a non-limiting example, the first electrode may be a transparent conductive electrode, and the transparent conductive electrode may be one or more selected from the group consisting of fluorine-doped tin oxide (FTO), indium-doped tin oxide (ITO), zinc oxide, carbon nanotubes, graphene, and combinations thereof, but the present invention is not limited thereto.

[0138] The electron transport layer may be an electron-conducting organic layer, an electron-conducting inorganic layer, or a laminate thereof.

[0139] The electron-conducting organic material may be an organic material used as an n-type semiconductor in a conventional organic optoelectronic device. Specific examples include, but are not limited to, fullerene derivatives including fullerene (C60, C70, C74, C76, C78, ​​C82, C95), PCBM ([6,6]-phenyl-C61-butyric acid methyl ester), and C71-PCBM, C84-PCBM, PC70BM ([6,6]-phenyl C70-butyric acid methyl ester), PBI (polybenzimidazole), PTCBI (3,4,9,10-perylenetetracarboxylic bisbenzimidazole), F4-TCNQ (tetra-uorotetracyanoquinodimethane), and mixtures thereof.

[0140] The electronically conductive inorganic material may be an electronically conductive metal oxide used for electron transfer in conventional quantum dot-based solar cells or dye-sensitized solar cells. As a specific example, the electronically conductive metal oxide may be an n-type metal oxide semiconductor. Examples of n-type metal oxide semiconductors include one or more materials selected from Ti oxide, Zn oxide, In oxide, Sn oxide, W oxide, Nb oxide, Mo oxide, Mg oxide, Ba oxide, Zr oxide, Sr oxide, Yr oxide, La oxide, V oxide, Al oxide, Y oxide, Sc oxide, Sm oxide, Ga oxide, In oxide, and SrTi oxide, and may include mixtures thereof or composite oxides thereof, but are not limited thereto.

[0141] The thickness of the electron transport layer may be 50 nm to 10 μm, specifically 50 nm to 1000 nm, but the present disclosure is not limited thereto.

[0142] The hole transport layer may include an organic hole transport layer, an inorganic hole transport layer, or a stack thereof.

[0143] The inorganic hole transport layer may include oxide semiconductors, sulfide semiconductors, halide semiconductors, or mixtures thereof, which have hole conductivity and are, i.e., p-type semiconductors. Specific examples include NiO, CuO, CuAlO2, CuGaO2, etc., examples of oxide semiconductors include PbS, and examples of halide semiconductors include PbI2, but the present disclosure is not limited to the inorganic hole transport layer material. The thickness of the inorganic hole transport layer may be 50 nm to 10 μm, specifically 10 nm to 1000 nm, more specifically 50 nm to 1000 nm.

[0144] The organic hole transport layer may include an organic hole transport material, specifically a monomeric to polymeric organic hole transport material (hole-conducting organic material). Any organic hole transport material used in conventional inorganic semiconductor-based solar cells that use inorganic semiconductor quantum dots as dyes may be used. Non-limiting examples of monomeric to low molecular weight organic hole transport materials include pentacene, coumarin 6 (coumarin 6, 3-(2-benzothiazolyl)-7-(diethylamino)coumarin), ZnPC (zinc phthalocyanine), CuPC (copper phthalocyanine), TiOPC (titanium oxide phthalocyanine), Spiro-MeOTAD (2,2',7,7'-tetrakis(N,Np-dimethoxyphenylamino)-9,9'-spirobifluorene), F16CuPC (copper(II) 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro-29H,31H-phthalocyanine), SubPc (boron subphthalocyanine chloride), and One or more substances selected from N3(cis-di(thiocyanato)-bis(2,2'-bipyridyl-4,4'-dicarboxylic acid)-ruthenium(II)) may be used, but are not limited thereto.

[0145] When the organic hole transport material is a polymer, examples of hole-conducting polymers include one or more materials selected from thiophene-based, paraphenylene vinylene-based, carbazole-based, and triphenylamine-based materials, but are not limited thereto. Non-limiting examples of polymeric organic hole transport materials include P3HT (poly[3-hexylthiophene]), MDMO-PPV (poly[2-methoxy-5-(3',7'-dimethyloctyloxyl)]-1,4-phenylene vinylene), MEH-PPV (poly[2-methoxy -5-(2''-ethylhexyloxy)-p-phenylene vinylene]), P3OT(poly(3-octyl thiophene)), POT(poly(octyl thiophene)), P3DT(poly(3-decyl thiophene)), P3DDT(poly(3-dodecyl thiophene), PPV(poly(p-phenylene vinylene)), TFB(poly(9,9'-dioctylfluorene-co-N-(4-butylphenyl)diphenyl amine), Polyaniline, Spiro-MeOTAD ([2,22′,7,77′-tetrkis (N,N-di-p-methoxyphenyl amine)-9,9,9′-spirobi fluorine]), PCPDTBT(Poly[2,1,3-benzothiadiazole- 4,7-diyl[4,4-bis(2-ethylhexyl-4H- cyclopenta [2,1-b:3,4-b']dithiophene-2,6-diyl]], Si-PCPDTBT(poly[(4,4′-bis(2-ethylhexyl)dithieno[3,2-b:2′,3′-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl]), PBDTTPD(poly((4,8-diethylhexyloxyl) benzo([1,2-b:4,5-b']dithiophene)-2,6-diyl)-alt-((5-octylthieno[3,4-c]pyrrole-4,6-dione)-1,3-diyl)), PFDTBT(poly[2,7-(9-(2-ethylhexyl)-9-hexyl-fluorene)-alt-5,5-(4', 7, -di-2-thienyl-2',1', 3'-benzothiadiazole)]), PFO-DBT(poly[2,7-.9,9-(dioctyl-fluorene)-alt-5,5-(4',7'-di-2-.thienyl-2', 1', 3'-benzothiadiazole)]), PSiFDTBT(poly[(2,7-dioctylsilafluorene)-2,7-diyl-alt-(4,7-bis(2-thienyl)-2,1,3-benzothiadiazole)-5,5′-diyl]), PSBTBT(poly[(4,4′-bis(2-ethylhexyl)dithieno[3,2-b:2′,3′-d]silole)-2,6-diyl-alt-(2,1,3-benzothiadiazole)-4,7-diyl]), PCDTBT(Poly [[9-(1-octylnonyl)-9H-carbazole-2,7-diyl] -2,5-thiophenediyl -2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl]), PFB(poly(9,9′-dioctylfluorene-co-bis(N,N′-(4,butylphenyl))bis(N,N′-phenyl-1,4-phenylene)diamine), F8BT(poly(9,9′-dioctylfluorene-co-benzothiadiazole), PEDOT (poly(3,4-ethylenedioxythiophene)), PEDOT:PSS (poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate)), PTAA (poly(triarylamine)), Poly(4-butylphenyl-diphenyl-amine) 및 이들의 공중합체에서 하나 또는 둘 이상 선택된 물질을 들 수 있으나,It is not limited thereto. Of course, the hole transport layer may further contain known additives such as TBP (tertiary butyl pyridine), LiTFSI (Lithium Bis(Trifluoromethanesulfonyl)Imide), HTFSI (bis(trifluoromethane) sulfonimide), 2,6-lutidine, and Tris(2-(1H-pyrazol-1-yl)pyridine)cobalt(III). Specifically, the hole transport layer may be a thin film of an organic hole transport material, and the thickness of the thin film may be 10 to 500 nm, but is not limited thereto.

[0146] The thickness of the light absorption layer may be 1 to 2,000 nm, specifically 10 to 1,000 nm, more specifically 50 to 800 nm. Such a thickness is preferred because it can sufficiently secure a photoactive region that absorbs light to generate photoelectrons and photoholes while preventing current dissipation due to recombination during photocurrent movement, and can sufficiently absorb the irradiated light, but the present disclosure is not limited by the thickness of the light absorption layer.

[0147] The second electrode may be a conductive electrode that is ohmic-bonded to the perovskite thin film, and since the work function is different from that of the first electrode, electrons and holes generated in the photoactive layer by the photoelectric effect may be transferred to the first electrode and the second electrode, respectively, thereby generating a photocurrent. As a non-limiting example, the second electrode may be one or more selected from the group consisting of gold (Au), silver (Ag), platinum (Pt), palladium (Pd), copper (Cu), aluminum (Al), carbon, cobalt sulfide, copper sulfide, nickel oxide, and combinations thereof, but the present disclosure is not limited thereto.

[0148] The present invention will be explained in more detail below through examples.

[0149] Physical Property Evaluation Methods

[0150] XRD Analysis: X-ray diffraction (XRD) analysis was performed using the Rigaku D / MAX2500V / PC X-ray diffraction analyzer under the following conditions.

[0151] - Light Source (X-ray Source): Cu-Kα radiation

[0152] - Power: 40 KV x 30mA

[0153] - Mode: Continuous Scan Mode

[0154] - Scan angle range: 5°-30°

[0155] - Scan speed: 0.02° / min

[0156] Crystal structure analysis: The crystal structure of the surface of the photoactive layer was observed using a scanning electron microscope (Cold FE-SEM, SU-8220).

[0157] Crystal size distribution: The crystal size distribution of the photoactive layer was calculated using Image J software based on the data obtained through the scanning electron microscope mentioned above.

[0158] Optoelectronic device performance evaluation: Current density-voltage (JV) characteristics with AM1.5 filter and 100 mW cm⁻¹ -2 Measurements were taken using a solar simulator (Newport, Oriel Sol3A class AAA) with an irradiation intensity and a Keithley 2420 source meter. To avoid overestimation of photocurrent density, the active area was determined by a metal mask placed in front of the solar cell. Except for the case of large-area measurements of 1 cm x 1 cm, the active area for current density-voltage measurements of the perovskite photovoltaic device was 4 mm x 4 mm. A spectral mismatch factor of 1.05 was used for all JV measurements.

[0159] Max Power Point Tracking Stability Test: 1 Sun, AM 1.5G Lighting, Max Power Point Voltage (VMPP After fixing the voltage with ), the current output was tracked to perform a stability test during continuous maximum power point operation, and the SPO (Stabilized power output) was calculated.

[0160] (Preparation Example 1)

[0161] 1.52 mL of 3-phenyl-1-propylamine was added dropwise to 1.4 mL of HCl and stirred in an ice bath for 1 hour. Then, the solvent was removed using a rotary evaporator at 60°C to recover the crystals. The resulting crystals were recrystallized with ethanol and diethyl ether and dried at 60°C overnight to prepare phenylpropyl ammonium chloride (hereinafter referred to as PPACl).

[0162] (Example 1)

[0163] A perovskite precursor solution was prepared by dissolving 0.7 M cesium iodide (CsI), 0.3 M formamidinium iodide (FAI), 1.0 M lead iodide (PbI2), and 50 mol% dimethylammonium iodide (DMAI) in a mixed solvent containing dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a 5:5 ratio. A mixed precursor solution was prepared by adding 5 mol% of PPACl from Preparation Example 1 to the perovskite precursor solution and stirring.

[0164] The above mixed precursor solution was spin-coated onto a substrate at 3,000 rpm for 30 seconds, then evacuated for 5 minutes at a pressure of 6.5 mTorr or less, and annealed at 170°C for 40 minutes. Subsequently, a diaminobenzidine (DAB) solution (in IPA 2 mg / ml) was spin-coated onto the annealed perovskite precursor solution at 5,000 rpm for 30 seconds, and annealed at 100°C for 10 minutes to prepare a photoactive layer.

[0165] (Comparative Example 1)

[0166] A photoactive layer was prepared in the same manner as in Example 1, except that the PPACl of Preparation Example 1 was not added to the above perovskite precursor solution.

[0167] (Comparative Example 2)

[0168] A photoactive layer was prepared in the same manner as in Example 1, except that methyl ammonium chloride (MACl) was added to the perovskite precursor solution instead of PPACl of Preparation Example 1.

[0169] (Evaluation Example 1) Crystal Structure Evaluation

[0170] Figure 2a shows the XRD analysis spectra of photoactive layers prepared by the methods according to Example 1 (PPACl), Comparative Example 1 (Control), and Comparative Example 2 (MACl), respectively. Referring to Figure 2a, a first peak at 2θ = 14˚±0.5˚ and a second peak at 2θ = 28˚±1.0˚ were detected in all of Example 1, Comparative Example 1, and Comparative Example 2. However, compared to Comparative Examples 1 and 2, the photoactive layer of Example 1 showed significantly higher intensities of the first and second peaks, confirming that the crystallinity was improved.

[0171] More specifically, FIG. 2b is a graph showing the full width half maximum (FWHM) of the first peak and the intensity of the first peak as a result of XRD analysis of photoactive layers prepared according to the methods of Example 1 (PPACl), Comparative Example 1 (Control), and Comparative Example 2 (MACl), respectively.

[0172] When comparing the full width half maximum (FWHM) of the first peak originating from the (110) plane of the photoactive layer, the photoactive layers of Comparative Example 1 and Comparative Example 2 had a wide first peak width of 14.6˚ and 15.2˚, respectively, but the photoactive layer of Example 1 showed a very small value of 0.091˚ for the full width half maximum (FWHM) of the first peak, confirming that the crystallinity of the (110) plane was significantly improved.

[0173] FIG. 2c is a histogram showing scanning electron microscope (SEM) images and crystal size distributions of photoactive layers prepared by the methods according to Example 1 (PPACl), Comparative Example 1 (Control), and Comparative Example 2 (MACl), respectively. Referring to FIG. 2c, the crystal size of the photoactive layer of Example 1 was improved compared to Comparative Examples 1 and 2, and the average crystal size was also the highest at 486 nm.

[0174] (Example 2)

[0175] FTO (F-doped tin oxide) glass substrate (Asahi VU glass, 12-13 Ω / cm 2 ) was prepared by sequentially sonicating in deionized water, acetone, and ethanol for 20 minutes each. A solution of titanium diisopropoxide bis(acetylacetonate) dissolved in ethanol (99.9%) at 20 mM was spray-pyrolyzed onto the FTO substrate at 450°C to deposit a TiO2 layer.

[0176] A perovskite precursor solution was prepared by dissolving 0.7 M cesium iodide (CsI), 0.3 M formamidinium iodide (FAI), 1.0 M lead iodide (PbI2), and 50 mol% dimethylammonium iodide (DMAI) in a mixed solvent containing dimethylformamide (DMF) and dimethyl sulfoxide (DMSO) in a 5:5 ratio. A mixed precursor solution was prepared by adding 5 mol% of PPACl from Preparation Example 1 to the perovskite precursor solution and stirring.

[0177] A first material layer was prepared by spin-coating the above mixed precursor solution onto a TiO2 layer at 3,000 rpm for 30 seconds, then evacuating for 5 minutes at a pressure of 6.5 mTorr or less, and annealing at 170°C for 40 minutes. Subsequently, a diaminobenzidine (DAB) solution (in IPA 2 mg / ml) was applied onto the first material layer by spin-coating at 5,000 rpm for 30 seconds, and annealing at 100°C for 10 minutes to prepare a photoactive layer.

[0178] A spiro-OMeTAD solution was prepared by adding 94 mg of Spiro-OMeTAD, 37 μl of t-BP, 23 μl of Li-TFSI (520 mg / ml in ACN), and 9 μl of Co-TFSI (375 mg / ml in ACN) to 1.1 mL of chlorobenzene and stirring. A hole transport layer was prepared by spin-coating the spiro-OMeTAD solution onto the photoactive layer at 3,500 rpm for 30 seconds.

[0179] Subsequently, a perovskite photovoltaic device was fabricated by stacking an 80 nm thick gold (Au) electrode on the hole transport layer using physical vapor deposition (PVD).

[0180] (Comparative Example 3)

[0181] A perovskite photovoltaic device was prepared in the same manner as in Example 1, except that the PPACl of Preparation Example 1 was not added to the above perovskite precursor solution.

[0182] (Comparative Example 4)

[0183] A perovskite photovoltaic device was prepared in the same manner as in Example 1, except that methyl ammonium chloride (MACl) was added to the perovskite precursor solution instead of PPACl of Preparation Example 1.

[0184] (Comparative Example 5)

[0185] A first material layer was prepared by spin-coating and annealing a perovskite precursor solution onto a TiO2 layer, and then a diaminobenzidine (DAB) solution (in IPA 2 mg / ml) was spin-coated onto the annealed perovskite precursor solution. After annealing, the PPACl of Preparation Example 1 was spin-coated at 3000 rpm for 30 seconds. Subsequently, a perovskite photovoltaic device was prepared in the same manner as in Example 1, except that a photoactive layer was prepared by heat-treating at 100°C for 3 minutes.

[0186] (Evaluation Example 2) Performance evaluation of optoelectronic devices

[0187] Open-circuit voltage (V) of a perovskite photovoltaic device oc ), short-circuit current density (J sc The fill factor (FF) and photoelectric conversion efficiency (PCE) were measured and are shown in Table 1 and Figure 3 below.

[0188] V oc [V] J sc [mA / cm 2 ] FF [%] PCE [%] Example 2 1.23 21.43 81.36 21.42 Comparative Example 3 1.07 20.1 70.36 15.1 Comparative Example 4 1.15 21.08 77.54 18.76 Comparative Example 5 1.17 21.12 77.94 19.53

[0189] Referring to Table 1 and Figure 3, the perovskite photovoltaic device of Example 2 (Target), in which the photoactive layer contains PPACl, exhibited the best open-circuit voltage, short-circuit current density, fill factor, and photovoltaic conversion efficiency. However, the perovskite photovoltaic devices of Comparative Example 4 (Control), in which the photoactive layer contains methylammonium chloride, and Comparative Example 3, in which the photoactive layer does not contain PPACl, showed significantly inferior performance compared to Example 2.

[0190] The perovskite photovoltaic device of Comparative Example 5 contains PPACl, but the perovskite photovoltaic device was manufactured by applying and heat-treating a perovskite precursor solution to form a photoactive layer, and then applying PPACl to the surface of the photoactive layer, resulting in low photovoltaic device performance.

[0191] (Evaluation Example 3) Photostability Evaluation

[0192] The photostability of perovskite photovoltaic devices according to Example 2 (Target) and Comparative Example 4 (Control) was evaluated and is shown in Table 2 and Figure 4 below. In Table 2 below, the SPO reduction rate was calculated using Equation 1 below.

[0193] Voltage [V] Initial SPO[%] SPO[%] after 600 sec SPO Reduction Rate[%] Example 2 0.96 20.17 19.57 2.97 Comparative Example 3 0.73 13.64 9.43 21.2 Comparative Example 4 0.81 16.37 12.90 30.9 Comparative Example 5 0.89 18.67 15.01 19.6

[0194] [Equation 1]

[0195]

[0196] (In Equation 1 above, S0 represents the initial SPO, and S1 represents the SPO after 600 seconds.)

[0197] As shown in Table 2 and Figure 4, when comparing the stabilized power outputs (hereinafter referred to as SPO) of perovskite photovoltaic devices, the perovskite photovoltaic device of Comparative Example 4 showed a low SPO of 16.37% at 0.81V, and the SPO decreased sharply to 12.90% after 600 seconds. Comparative Example 3 also showed a lower SPO value than Comparative Example 4, and the SPO decreased significantly to 9.43% after 600 seconds. The perovskite photovoltaic device of Comparative Example 5 showed a slightly higher SPO value than Comparative Examples 3 and 4, but the SPO value after 600 seconds was 15.01%, showing a high SPO reduction rate of 21%.

[0198] On the other hand, the perovskite photovoltaic device of Example 2 had a high initial SPO of 20.17% at 0.96V and showed an SPO of 19.57% even after 600 seconds, so the SPO value hardly decreased. Accordingly, it was confirmed that a perovskite photovoltaic device with excellent photostability was realized.

[0199] As described above, the present invention has been explained by specific details, limited embodiments, and drawings; however, this is provided merely to aid in a more comprehensive understanding of the invention and is not limited to the above embodiments. Those skilled in the art can make various modifications and variations from this description.

[0200] Accordingly, the scope of the present invention is not limited to the described embodiments, and all things equivalent to or having equivalent variations to the claims set forth below, as well as the claims set forth below, shall be considered to fall within the scope of the concept of the present invention.

Claims

Claim 1 A photoactive layer for a perovskite photovoltaic device, comprising: a first layer comprising a first perovskite compound having a three-dimensional crystal structure; a second layer located on at least one surface of the first layer and comprising a second perovskite compound having a two-dimensional or quasi-two-dimensional crystal structure and satisfying the following chemical formula 5; and an organic ammonium halide compound represented by the following chemical formula 1 dispersed in at least one of the first layer and the second layer. [Chemical Formula 1]RNH3 + X - (In the above Formula 1, R is a substituted or unsubstituted C6-C30 aryl group; C7-C40 arylalkyl group; C7-C40 arylalkenyl group; or C3-C30 cycloalkyl group; and X is F, Cl, Br or I)[Formula 5](RNH3)2(Cs x FA 1-x ) m-1 Pb m I 3m+1 (In the above chemical formula 5, R is a substituted or unsubstituted C6-C30 aryl group; a C7-C40 arylalkyl group; a C7-C40 arylalkenyl group; or a C3-C30 cycloalkyl group; and m is a real number from 2 to 10) Claim 2 In claim 1, the second perovskite compound is a photoactive layer for a perovskite photovoltaic device represented by the following chemical formula 2 or chemical formula 3. [Chemical Formula 2]A 2n B n X 3n+1 [Chemical Formula 3]A 2m-1 B m X 3m+1 (In the above Chemical Formulas 2 and 3, A is each independently a monovalent organic ammonium cation; a monovalent amidinium cation; Li + ; Na + ; K + ; Rb + ; Cs + ; Fr + ; Cu(I) + ; Ag(I) + ; and Au(I) + ; is a monovalent cation comprising one or more selected from, B is independently a divalent metal cation, and X is independently F - , I - , Br - , Cl - or a halogen anion comprising a combination thereof, where n is a real number from 0 to 5 and m is a real number from 2 to 10) Claim 3 A photoactive layer for a perovskite photovoltaic device according to claim 1, wherein the organic ammonium halide compound comprises propyl phenyl ammonium chloride (PPACl). Claim 4 A photoactive layer for a perovskite photovoltaic device according to claim 1, wherein in the XRD spectrum of the photoactive layer for a perovskite photovoltaic device, the full width half maximum (FWHM) of the first peak appearing at a diffraction angle of 2θ = 14˚±0.5˚ is 0.14˚ or less. Claim 5 A photoactive layer for a perovskite photovoltaic device according to claim 1, wherein the average crystal size of the second perovskite compound is 450 to 600 nm. Claim 6 In claim 1, in the XRD spectrum of the photoactive layer for the perovskite photovoltaic device, the intensities of the first peak appearing at a diffraction angle of 2θ = 14˚±0.5˚ and the second peak appearing at a diffraction angle of 2θ = 28˚±1.0˚ are each independently 1 x 10 4 Photoactive layer for perovskite photovoltaic devices with cps or higher. Claim 7 In claim 1, the first perovskite compound is a photoactive layer for a perovskite photovoltaic device represented by the following chemical formula 4. [Chemical Formula 4] ABX3 (wherein A is a monovalent organic ammonium cation; a monovalent amidinium cation; Li + ; Na + ; K + ; Rb + ; Cs + ; Fr + ; Cu(I) + ; Ag(I) + ; and Au(I) + ; is a monovalent cation comprising one or more selected from, B is a divalent metal cation, and X is F - , I - , Br - , Cl - or is a halogen anion containing a combination thereof) Claim 8 In claim 1, at least one of the first perovskite compound and the second perovskite compound is a monovalent organic ammonium ion (RNH3) contained in the organic ammonium halide compound. + A photoactive layer for a perovskite photovoltaic device comprising ). Claim 9 In claim 1, the second perovskite compound is a photoactive layer for a perovskite photovoltaic device having a crystal structure of 1 to 10 layers. Claim 10 In claim 1, the second perovskite compound is a photoactive layer for a perovskite photovoltaic device having a quasi-two-dimensional crystal structure. Claim 11 delete Claim 12 A perovskite photovoltaic device comprising a photoactive layer for a perovskite photovoltaic device according to any one of claims 1 to 10. Claim 13 A perovskite photovoltaic device according to claim 12, further comprising: an electron transport layer located on one side of the photoactive layer for the perovskite photovoltaic device; a hole transport layer located on the other side of the photoactive layer for the perovskite photovoltaic device; a first electrode located on one side of the electron transport layer; and a second electrode located on one side of the hole transport layer. Claim 14 A perovskite photovoltaic device according to claim 13, wherein the hole transport layer is located on the surface in contact with the second layer of the photoactive layer for the perovskite photovoltaic device. Claim 15 In paragraph 12, a perovskite photovoltaic device having a power conversion efficiency (PCE) of 19% or more.

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