Self-assembled two-dimensional perovskite-based optoelectronic device

Abstract

The present application relates to an optoelectronic device comprising a two-dimensional perovskite self-assembled between a perovskite and an electron transport layer, and to a method for manufacturing same. A perovskite optoelectronic device, according to embodiments of the present application, may comprise a two-dimensional perovskite (as a non-limiting example, OA 2PbI4) self-assembled between an electron transport layer and a perovskite layer, whereby defects such as oxygen vacancies formed on the surface of the electron transport layer are eliminated, the band structure at the interface between the electron transport layer and the perovskite is aligned, and a passivation effect of the perovskite may be realized. Accordingly, the efficiency of the device may be improved, and long-term stability may be improved.

Description

Self-assembled two-dimensional perovskite-based photovoltaic devices

[0001] The present invention relates to a photovoltaic device comprising a two-dimensional perovskite formed by self-assembly between a perovskite and an electron transport layer, and a method for manufacturing the same.

[0002] Metal halide perovskite solar cells (MHPS) have attracted significant attention due to their continuously improving power conversion efficiency (PCE), cost-effective materials, and simple solution-based fabrication processes. However, halide-based perovskites suffer from electronic and ionic conduction, primarily driven by iodine vacancies that cause unbalanced local stoichiometry. This leads to degradation of the perovskite material in narrow-bandgap perovskites and phase separation in wide-bandgap perovskites. Furthermore, charge accumulation at the interface, which contributes to early degradation, is influenced by the electron transport layer (ETL) composed of oxide materials.

[0003] To address these issues and improve the performance of solar cell devices, various passivation strategies for perovskites have been studied, ranging from the introduction of additives during precursor synthesis to interfacial passivation applied above or below the perovskite layer. However, certain passivation materials for solar cells have problems such as the accumulation of ionic defects at the interface and bulk heterogeneity, which are major factors in degrading device performance.

[0004] [Prior Art Literature]

[0005] [Non-patent literature]

[0006] Park, B. wook et al. Publisher Correction: Stabilization of formamidinium lead triiodide α-phase with isopropylammonium chloride for perovskite solar cells (Nature Energy, (2021), 6, 4, (419-428), 10.1038 / s41560-021-00802-z). Nat. Energy 6, 848 (2021).

[0007] The present invention relates to a photovoltaic device comprising a two-dimensional perovskite formed by self-assembly between a perovskite and an electron transport layer, and a method for manufacturing the same.

[0008] However, the problems that the present invention seeks to solve are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the description below.

[0009] The first aspect of the present invention provides a perovskite photoelectric device comprising: a first passivation layer comprising an ammonium salt; an electron transport layer formed on the first passivation layer and comprising a metal oxide; a perovskite layer formed on the electron transport layer; and a second passivation layer formed on the perovskite layer and comprising a compound represented by the following chemical formula 1, wherein the perovskite photoelectric device comprises a two-dimensional perovskite at an interface between the electron transport layer and the perovskite layer:

[0010] [Chemical Formula 1]

[0011] R 1 NH3X 1 ,

[0012] In the above chemical formula 1,

[0013] R 1 Silver C 5-20 is an alkyl group, and X 1 is F, Cl, Br, or I.

[0014] A second aspect of the present invention provides a method for manufacturing a perovskite photoelectric device, comprising: forming a first passivation layer comprising an ammonium salt on a first electrode; forming an electron transport layer comprising a metal oxide on the first passivation layer; forming a perovskite layer on the electron transport layer; and forming a second passivation layer comprising a compound represented by the chemical formula 1 on the perovskite layer, wherein a two-dimensional perovskite is formed by self-assembly at an interface between the electron transport layer and the perovskite layer.

[0015] The perovskite photovoltaic device according to the embodiments of the present disclosure can have defects such as oxygen vacancies generated on the surface of the electron transport layer eliminated due to the two-dimensional perovskite (as a non-limiting example, OA2PbI4) self-assembled between the electron transport layer and the perovskite layer, the band structure of the interface between the electron transport layer and the perovskite aligned, and the passivation effect of the perovskite. Accordingly, the efficiency of the device can be improved and the long-term stability can be enhanced.

[0016] FIG. 1 is a schematic diagram showing the structure of perovskite photovoltaic devices (M1, M2, and M3) in one embodiment of the present invention.

[0017] FIG. 2 schematically illustrates ions formed according to passivation of the SnO2 electron transport layers of M1, M2, and M3 in one embodiment of the present invention.

[0018] Figure 3 is, in one embodiment of the present invention, (a) OA + and NH4 + Schematic diagram of the formation process of OA2PbI4, a two-dimensional perovskite, by diffusion of (a) NH4 obtained through computational simulation + It shows the value of the movement barrier.

[0019] FIG. 4 shows the results of C 1s X-ray photoelectron spectroscopy measurements at the SnO2 electron transport layer and perovskite interface of M1, M2, and M3 in one embodiment of the present invention.

[0020] Figures 5 a, b, and c show the results of cross-sectional transmission electron microscope measurements of M3, M2, and M1, respectively, in one embodiment of the present invention.

[0021] Figure 6 shows the results of photoluminescence measurements at the SnO2 electron transport layer and perovskite interface of M1, M2, and M3 in one embodiment of the present invention.

[0022] Figure 7 shows the results of scanning electron microscope measurements of the perovskite surfaces of M1, M2, and M3 in one embodiment of the present invention.

[0023] Figure 8 shows the results of X-ray diffraction measurements of the perovskite surfaces of M1, M2, and M3 in one embodiment of the present invention.

[0024] Figure 9 shows the results of time-of-flight secondary ion mass spectrometry measurements of M1 and M2 in one embodiment of the present invention.

[0025] Figure 10 shows the results of evaluating the photoelectric element characteristics of M1, M2, and M3 in one embodiment of the present invention.

[0026] Figure 11 shows the results of evaluating the long-term stability of the photoelectric elements of M1, M2, and M3 in one embodiment of the present invention.

[0027] Hereinafter, with reference to the attached drawings, implementation examples and embodiments of the present invention will be described in detail so that those skilled in the art can easily practice the present invention. However, the present invention may be implemented in various different forms and is not limited to the implementation examples and embodiments described herein. In addition, in the drawings, parts irrelevant to the description have been omitted to clearly explain the present invention, and similar parts have been designated with similar drawing reference numerals throughout the specification.

[0028] Throughout this specification, when a part is said to be "connected" to another part, this includes not only cases where it is "directly connected" but also cases where it is "electrically connected" with another element in between.

[0029] Throughout this specification, when it is said that an element is "on" another element, this includes not only cases where the element is in contact with the other element, but also cases where another element exists between the two elements.

[0030] Throughout this specification, whenever a part is said to "include" a component, this does not mean that it excludes other components, but rather that it may include other components, unless otherwise specifically stated.

[0031] The terms "about," "substantially," and the like used in this specification are used in a meaning that is at or close to the numerical value when manufacturing and material tolerances inherent in the meanings mentioned are presented, and are used to prevent unscrupulous infringers from unfairly exploiting the disclosure in which exact or absolute values ​​are mentioned to aid understanding of the present application.

[0032] The terms “step of ~” or “step of ~” as used throughout this specification do not mean “step for ~.”

[0033] Throughout this specification, the term "combination(s) thereof" included in the expressions in the Makushi format means one or more mixtures or combinations selected from the group consisting of the components described in the expressions in the Makushi format, and means including one or more selected from the group consisting of said components.

[0034] Throughout this specification, references to “A and / or B” mean “A or B, or A and B.”

[0035] As used throughout this specification, the term "alkyl" or "alkyl group" includes linear or branched alkyl groups having 1 to 20 carbon atoms, 1 to 15 carbon atoms, 1 to 10 carbon atoms, 1 to 8 carbon atoms, 1 to 5 carbon atoms, 5 to 20 carbon atoms, 5 to 15 carbon atoms, or 5 to 10 carbon atoms and all possible isomers thereof. For example, the alkyl or alkyl group may be a methyl group (Me), an ethyl group (Et), an n-propyl group ( n Pr), iso-profiler ( i Pr), n-butyl group ( n Bu), iso-butyl group( i Bu), tert-butyl group (tert-Bu, t Bu), sec-butyl group (sec-Bu, sec Bu), n-pentyl group ( n Pe), iso-pentyl group ( iso Pe), sec-pentyl group ( sec Pe), tert-pentyl group ( t Pe), neo-pentyl group ( neo Pe), 3-pentyl group, n-hexyl group, iso-hexyl group, heptyl group, 4,4-dimethylpentyl group, octyl group, 2,2,4-trimethylpentyl group, nonyl group, decyl group, undecyl group, dodecyl group, tridecyl group, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, isosyl group and isomers thereof, but may not be limited thereto.

[0036] Below, the implementation examples of the present invention are described in detail, but the present invention may not be limited thereto.

[0037] The first aspect of the present invention provides a perovskite photoelectric device comprising: a first passivation layer comprising an ammonium salt; an electron transport layer formed on the first passivation layer and comprising a metal oxide; a perovskite layer formed on the electron transport layer; and a second passivation layer formed on the perovskite layer and comprising a compound represented by the following chemical formula 1, wherein the perovskite photoelectric device comprises a two-dimensional perovskite at an interface between the electron transport layer and the perovskite layer:

[0038] [Chemical Formula 1]

[0039] R 1 NH3X 1 ,

[0040] In the above chemical formula 1, R 1 Silver C 5-20 is an alkyl group, and X 1 is F, Cl, Br, or I.

[0041] In one embodiment of the present invention, the ammonium salt is NH4Cl (ammonium chloride), NH4Br (ammonium bromide), NH4I (ammonium iodide), NH4F (ammonium fluoride), NH4NO3 (ammonium nitrate), (NH4)2CO3 (ammonium carbonate), NH4HCO3 (ammonium bicarbonate), (NH4)2SO4 (ammonium sulfate), (NH4)2S2O8 (ammonium persulfate), NH4HSO3 (ammonium bisulfite), NH4HSO4 (ammonium bisulfate), NH4ClO4 (ammonium perchlorate), CH3COONH4 (ammonium acetate), C6H5COONH4 (ammonium benzoate), NH4H2PO4 (ammonium dihydrogen phosphate), (NH4)2HPO4 (ammonium hydrogen phosphate), It may include, but is not limited to, one or more selected from NH4SCN (ammonium thiocyanate), NH4BF4 (ammonium tetrafluoroborate), and NH4PF6 (ammonium hexafluorophosphate).

[0042] In one embodiment of the present invention, the two-dimensional perovskite may be formed through self-assembly.

[0043] In one embodiment of the present invention, the perovskite may be represented by the following chemical formula 2, but may not be limited thereto:

[0044] [Chemical Formula 2]

[0045] AMX 2 3;

[0046] In the above chemical formula 2, A is a monovalent cation, an organic ammonium ion, an organic amidinium ion, a guanidinium ion, an organic phosphonium ion, an alkali metal ion, or a combination or derivative thereof, and M is a metal, a transition metal, a rare earth metal, an alkaline earth metal, an organic substance, an inorganic substance, ammonium, or a combination or derivative thereof, and X 2 can be a halogen ion such as F, Cl, Br, or I.

[0047] In one embodiment of the present invention, in the chemical formula 2, A may be a methylammonium ion, a formamidinium ion, an acetamidinium ion, or a guanidinium ion, but may not be limited thereto.

[0048] In one embodiment of the present invention, in the chemical formula 2, M may be Pb, Sn, Cu, Ni, Co, Fe, Mn, Pd, Cd, Ge, Cs, Eu, or a combination thereof, but may not be limited thereto.

[0049] In one embodiment of the present invention, X of the chemical formula 1 1 And X of the above chemical formula 2 2 may be identical to each other.

[0050] In one embodiment of the present invention, the two-dimensional perovskite may include a compound represented by the following chemical formula 3.

[0051] [Chemical Formula 3]

[0052] (R 1 NH3)2MX 1 4,

[0053] In the above chemical formula 3, R 1 Silver C 5-20 is an alkyl group, M is Pb, Sn, Cu, Ni, Co, Fe, Mn, Pd, Cd, Ge, Cs, Eu, or a combination thereof, and X 1 can be F, Cl, Br, or I.

[0054] In one embodiment of the present invention, in the chemical formula 1 or 3, R 1 Silver C 5-20 , C 5-15 , C 5-14 , C 5-13 , C 5-12 , C 5-11, C 5-10 , C 6-20 , C 6-15 , C 6-14 , C 6-13 , C 6-12 , C 6-11 , or C 6-10 It may be an alkyl group.

[0055] In one embodiment of the present invention, the two-dimensional perovskite may include OA2PbI4.

[0056] In one embodiment of the present invention, the metal oxide is SnO2, TiO2, ZnO, WO3, RuO2, La x Sr 1-x CoO3, La x Sr 1-x It comprises at least one selected from MnO3, BaSnO3 and LaNiO3, and may be 0 < x ≤ 0.5, but may not be limited thereto.

[0057] In one embodiment of the present invention, the first passivation layer is formed before the formation of the electron transport layer, and forming the first passivation layer may be referred to as pretreatment passivation of the electron transport layer.

[0058] In one embodiment of the present invention, NH4 from the first passivation layer + Ions can diffuse and exist on the surface of the electron transport layer.

[0059] In one embodiment of the present invention, R from the second passivation layer 1 NH3 + ions (including, but not limited to, OA) +(octylammonium) ions) and halogen ions can diffuse and exist on the upper part of the electron transport layer (the surface in contact with the perovskite layer). At this time, NH4 present on the surface of the electron transport layer + and the above R 1 NH3 + By substituting ions, a two-dimensional perovskite can be generated at the interface between the electron transport layer and the perovskite layer. More specifically, for example, if the perovskite layer includes FAPbI3 and the compound represented by the chemical formula 1 is OAI (octylammonium iodide), NH4 + When a FAPbI3 perovskite layer is formed on the surface of the electron transport layer, NH4PbI3 in a metaphase state is generated at the interface. At this time, NH4 + Since the migration barrier is low, NH4PbI3 to NH4 + diffuses into the perovskite layer, and OA existing on the upper part of the perovskite layer + NH4 diffuses to the surface of the electron transport layer + Go OA + By substituting with , two-dimensional OA2PbI4 can be generated at the interface between the electron transport layer and the perovskite layer.

[0060] In one embodiment of the present invention, the two-dimensional perovskite may exist mixed with a three-dimensional perovskite.

[0061] In one embodiment of the present invention, a two-dimensional-three-dimensional perovskite layer including the two-dimensional perovskite and the three-dimensional perovskite can be formed at the interface between the electron transport layer and the perovskite layer.

[0062] In one embodiment of the present invention, the two-dimensional perovskite may perform a passivation role similar to the first passivation layer and the second passivation layer.

[0063] In one embodiment of the present invention, due to the two-dimensional perovskite, defects such as oxygen vacancies generated on the surface of the electron transport layer are eliminated, and charge transfer from the perovskite layer to the electron transport layer is improved, so that the efficiency of the device can be improved.

[0064] In one embodiment of the present invention, charge transport can be improved through alignment of the band structure of the interface between the electron transport layer and the perovskite due to the two-dimensional perovskite. Since the conventional passivation method of the electron transport layer is a post-processing method of passivating after forming the electron transport layer, it was difficult to align the band structure of the interface between the perovskite and the electron transport layer. The two-dimensional perovskite of the present invention is formed in a stabilized form in a self-assembled form at the interface between the electron transport layer and the perovskite, and has the advantage of being able to align the band structure without artificially changing the band structure.

[0065] In one embodiment of the present invention, the two-dimensional perovskite causes a lower passivation effect of the perovskite layer, and the second passivation causes an upper passivation effect of the perovskite layer. Accordingly, the perovskite layer can have improved efficiency and efficiency stability through upper and lower double-sided passivation.

[0066] In one embodiment of the present invention, the C 1s X-ray photoelectron spectroscopy (XPS) spectrum of the interface between the electron transport layer and the perovskite layer may exhibit a peak detected at about 291 eV to about 294 eV by the two-dimensional perovskite (as a non-limiting example, OA2PbI4).

[0067] In one embodiment of the present invention, the photoluminescence (PL) spectrum of the interface between the electron transport layer and the perovskite layer may exhibit a peak detected at about 520 nm to about 530 nm by the two-dimensional perovskite (as a non-limiting example, OA2PbI4) layer.

[0068] In one embodiment of the present invention, the perovskite photovoltaic device may maintain a power conversion efficiency of about 90% or more, about 91% or more, or about 92% or more even after about 2000 hours.

[0069] In one embodiment of the present invention, the perovskite photovoltaic device may further include a substrate, a first electrode, a hole transport layer, and / or a second electrode.

[0070] In one embodiment of the present invention, the substrate, the first electrode, the hole transport layer, and the second electrode may be used without limitation as long as they are each commonly used in photoelectric devices. The substrate may include, but is not limited to, glass or a transparent polymer. The first electrode is a transparent electrode and may include, but is not limited to, ITO (indium tin oxide), IZO (In-ZnO), GZO (Ga-ZnO), AZO (Al-ZnO), AGZO (Al-Ga ZnO), IGZO (In-Ga ZnO), or FTO (fluorine-doped tin oxide). The hole transport layer may include, but is not limited to, Spiro-OMeTAD.

[0071] In one embodiment of the present invention, the perovskite photoelectric device may include a first electrode formed on a substrate; a first passivation layer formed on the first electrode and containing NH4Cl; an electron transport layer formed on the first passivation layer and containing a metal oxide; a perovskite layer formed on the electron transport layer; a second passivation layer formed on the perovskite layer and containing octylammonium iodide (OAI); a hole transport layer formed on the second passivation layer, and a second electrode formed on the hole transport layer.

[0072] A second aspect of the present invention provides a method for manufacturing a perovskite photoelectric device, comprising: forming a first passivation layer comprising an ammonium salt on a first electrode; forming an electron transport layer comprising a metal oxide on the first passivation layer; forming a perovskite layer on the electron transport layer; and forming a second passivation layer comprising a compound represented by the following chemical formula 1 on the perovskite layer, wherein a two-dimensional perovskite is formed by self-assembly at an interface between the electron transport layer and the perovskite layer.

[0073] [Chemical Formula 1]

[0074] R 1 NH3X 1 ,

[0075] In the above chemical formula 1,

[0076] R 1 Silver C 5-20 is an alkyl group, and X 1 is F, Cl, Br, or I.

[0077] Detailed descriptions of parts that overlap with the first aspect of the present application have been omitted, but the contents described in the first aspect of the present application may be equally applied even if the description is omitted in the second aspect of the present application.

[0078] In one embodiment of the present invention, the two-dimensional perovskite may include a compound represented by the following chemical formula 3:

[0079] [Chemical Formula 3]

[0080] (R 1 NH3)2MX 1 4,

[0081] In the above chemical formula 3,

[0082] R 1 Silver C 5-20 is an alkyl group, M is Pb, Sn, Cu, Ni, Co, Fe, Mn, Pd, Cd, Ge, Cs, Eu, or a combination thereof, and X 1 is F, Cl, Br, or I.

[0083] In one embodiment of the present invention, the two-dimensional perovskite may include OA2PbI4.

[0084] In one embodiment of the present invention, the metal oxide is SnO2, TiO2, ZnO, WO3, RuO2, La x Sr 1-x CoO3, La x Sr 1-x It comprises at least one selected from MnO3, BaSnO3 and LaNiO3, and 0 < x ≤ 0.5.

[0085] In one embodiment of the present invention, forming the first passivation layer may include, but is not limited to, applying a first passivation solution containing the ammonium salt.

[0086] In one embodiment of the present invention, the concentration of the ammonium salt of the first passivation solution may be from about 1 mM to about 1000 mM, but may not be limited thereto. In one embodiment of the present invention, the ammonium salt concentration of the first passivation solution may be, but is not limited to, about 1 mM to about 1000 mM, about 1 mM to about 100 mM, about 1 mM to about 50 mM, about 1 mM to about 40 mM, about 10 mM to about 1000 mM, about 10 mM to about 100 mM, about 10 mM to about 50 mM, about 10 mM to about 40 mM, about 30 mM to about 1000 mM, about 30 mM to about 100 mM, about 30 mM to about 50 mM, about 30 mM to about 40 mM, about 35 mM to about 1000 mM, about 35 mM to about 100 mM, about 35 mM to about 50 mM, or about 35 mM to about 40 mM.

[0087] In one embodiment of the present invention, forming the second passivation layer may include, but is not limited to, applying a second passivation solution including a compound represented by the chemical formula 1.

[0088] In one embodiment of the present invention, the concentration of the compound represented by Chemical Formula 1 in the second passivation solution may be from about 1 mM to about 1000 mM, but may not be limited thereto.

[0089] In one embodiment of the present invention, the concentration of the compound represented by Chemical Formula 1 in the second passivation solution may be, but is not limited to, about 1 mM to about 1000 mM, about 1 mM to about 100 mM, about 1 mM to about 50 mM, about 1 mM to about 30 mM, about 1 mM to about 20 mM, about 10 mM to about 1000 mM, about 10 mM to about 100 mM, about 10 mM to about 50 mM, about 10 mM to about 30 mM, about 10 mM to about 20 mM, about 15 mM to about 1000 mM, about 15 mM to about 100 mM, about 15 mM to about 50 mM, about 15 mM to about 30 mM, or about 15 mM to about 20 mM.

[0090] In one embodiment of the present invention, the application may be performed through a solution process. The solution process may include, but is not limited to, spin coating, dip coating, spin casting, or spraying.

[0091] In one embodiment of the present invention, after forming the first passivation layer, the electron transport layer, the perovskite layer, and the second passivation layer, it may further include heat treating and hardening each of them.

[0092] In one embodiment of the present invention, the heat treatment may be performed at a temperature range of about 50°C to about 300°C for about 5 minutes to about 100 minutes, but may not be limited thereto.

[0093] In one embodiment of the present invention, after forming the first passivation layer, the electron transport layer, and the second passivation layer, each may further include performing UV ozone treatment.

[0094] In one embodiment of the present invention, the UV ozone treatment may be performed for, but is not limited to, about 1 minute to about 100 minutes, about 1 minute to about 60 minutes, about 1 minute to about 30 minutes, about 1 minute to about 20 minutes, about 1 minute to about 10 minutes, about 5 minutes to about 100 minutes, about 5 minutes to about 60 minutes, about 5 minutes to about 30 minutes, about 5 minutes to about 20 minutes, or about 5 minutes to about 10 minutes.

[0095] Hereinafter, the present invention will be described in more detail using examples. However, the following examples are provided only to help understand the present invention, and the contents of the present invention are not limited to the following examples.

[0096] [Example]

[0097] 1. Component manufacturing

[0098] Perovskite photovoltaic devices with three structures, M1, M2, and M3, were fabricated depending on the application of the passivation layer (Fig. 1).

[0099] 1) Formation and passivation treatment of SnO2 electron transport layer

[0100] SnO2 solution was prepared by mixing SnO2 nanoparticle solution and deionized water. In addition, NH4Cl powder was dissolved in ethanol to prepare a 37.4 mM NH4Cl passivation solution. Glass / ITO (indium tin oxide) substrates were washed and then treated with UV ozone for 20 minutes. To fabricate M1, 200 μL of SnO2 solution was applied onto a glass / ITO substrate, spin-coated at 4000 rpm for 30 seconds, and then heat-treated on a hot plate at 150°C for 30 minutes to form a SnO2 thin film. To fabricate M2, a SnO2 thin film was formed on a glass / ITO substrate using the same method as above, and treated with UV ozone for 20 minutes. After that, 150 μL of NH4Cl solution was applied onto the SnO2 thin film, spin-coated at 5000 rpm for 20 seconds, and then heat-treated on a hot plate at 70°C for 10 minutes to form an NH4Cl thin film. To fabricate M3, an NH4Cl thin film was formed on a glass / ITO substrate using the same method as above, and UV ozone treatment was performed for 10 minutes. Then, an SnO2 thin film was formed on the NH4Cl thin film using the same method as above.

[0101] Figure 2 schematically illustrates ions formed on a SnO2 electron transport layer according to passivation treatment of the SnO2 electron transport layer.

[0102] 2) Formation of perovskite layer and passivation treatment

[0103] Synthesis of formamidinium iodide (FAI)

[0104] 15 g of formamidine acetate (FA acetate) powder was placed in a round flask, placed in an ice bath, and 40 mL of hydroiodic acid (HI) was slowly added while stirring for 2 hours. Afterwards, the solvent HI was removed using a rotary evaporator with controlled vacuum pressure at 65°C, obtaining yellow and white precipitates. The precipitate was washed several times with ether until the powder turned pure white. The white precipitate was dissolved in ethanol and recrystallized by adding ether. This process was repeated twice. Finally, FAI powder was obtained and dried in a vacuum oven for 24 hours.

[0105] Synthesis of FAPbI3 single crystals

[0106] FAI powder (1.5 M) and PbI2 powder (1.5 M) were dissolved in a gamma-butyrolactone (GBL) solution for 24 h. After filtering using a 0.2 μm filter, single crystals were grown on a 120°C hot plate for 3 h. The obtained black FAPbI3 single crystals were then washed with an acetonitrile solution and then with an ether solution. The washed single crystals were dried on a 150°C hot plate for 30 min.

[0107] Perovskite precursor manufacturing

[0108] DMF (N,N-dimethylformamide) and DMSO (dimethyl sulfoxide) were mixed in a volume ratio of 8:1. FAPbI3 single crystal and MACl (methylammonium chloride) (20 mol%) were dissolved in the mixed solution to a concentration of 1.6 M each to prepare a perovskite precursor solution.

[0109] Formation and passivation of perovskite layers

[0110] 70 μL of the perovskite precursor solution was applied onto the SnO2 electron transport layer and spin-coated at 4000 rpm for 25 s. 10 s before the end of spin-coating, 800 μL of ether was added to remove the solvent. The spin-coated thin film was then heat-treated on a 150°C hot plate for 10 min. The perovskite passivation solution was a 15 mM OAI solution prepared by dissolving 0.0193 g of OAI in 5 mL of isopropyl alcohol (IPA). After applying the OAI solution to the surface of the perovskite thin film, spin-coating was performed at 3000 rpm for 30 s to form a passivation layer.

[0111] 3) Formation of hole transport layer and electrode

[0112] HTL was prepared using a spiro-OMeTAD solution consisting of 72.3 mg of spiro-OMeTAD powder dissolved in 1 mL of chlorobenzene along with a stock solution of 30 μL of 4-tert-butylpyridine (tBP) and 35 μL of lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI). The HTL solution was applied onto the perovskite and spin-coated at 3000 rpm for 25 s. Subsequently, a 100 nm-thick gold electrode was formed using a thermal evaporation method.

[0113] 2. Results and Analysis

[0114] NH4 + When a FAPbI3 perovskite layer is formed on the surface of the electron transport layer, NH4PbI3 in a metaphase state is generated at the interface. At this time, NH4 + Since the migration barrier is low, NH4PbI3 to NH4 + diffuses into the perovskite layer, and OA existing on the upper part of the perovskite layer +NH4 diffuses to the surface of the electron transport layer (SnO2) + Go OA + , a two-dimensional OA2PbI4 can be generated at the interface between the electron transport layer and the perovskite layer. Figure 3a is OA + and NH4 + A schematic diagram of the process of forming OA2PbI4, a two-dimensional perovskite, by diffusion of NH4 is shown in Fig. 3b, obtained through computational simulation. + As shown in the mobility barrier value, NH4 due to the low mobility barrier value of 0.21 eV + It is easy to move into the FAPbI3.

[0115] Figure 4 shows the results of C 1s X-ray photoelectron spectroscopy (XPS) measurements at the SnO 2 electron transport layer and perovskite interface of M1, M2, and M3. In M3, the formation of the OA 2 Pb I 4 two-dimensional perovskite phase was confirmed from the peak around 292 eV. No peak due to OA 2 Pb I 4 was observed in M1 and M2.

[0116] Table 1 below shows the peak positions of XPS in Fig. 4.

[0117] CC / C-HC-N (OA)C=O (FA)π-π (OA2PbI4)M1Peak position284.50553286.0116288.0671N / AFWHM1.263561.266021.27248N / AArea3358.40806796.432233388.92335N / AM2Peak position284.44447285.4593287.97594N / AFWHM1.196612.5471.70696N / AArea1443.02752857.133121144.13754N / AM3Peak position284.42466285.53015288.02152292.72505FWHM1.197191.939961.96311.01751Area1343.9583669.76246830.48344150.69262

[0118] Figures 5 a, b, and c are cross-sectional transmission electron microscope images of M3, M2, and M1, respectively. Referring to Figure 5 a, NH4 in M3 + - Self-assembled 2D-OA2PbI4(n=1) structures can be observed near the SnO2 interface, which can be confirmed to be mixed with three-dimensional (3D) perovskite structures. 2D perovskite formation occurs between 3D perovskite structures, generating a 2D-3D mixed perovskite phase at the buried interface. In particular, OA + NH4 through the cation diffusion process and subsequent reaction with the existing metaphase NH4PbI3 structure. + -A mixed 2D-3D perovskite phase was formed near the SnO2 buried interface. The interlayer spacing for the PbI2(001) plane of the 2D-OA2PbI4 lattice was measured to be 0.8 nm, which is OA +Because the size of the cations is large, the interlayer spacing of the typical 3D perovskite structure showed a larger value. On the other hand, referring to Fig. 5 b and c, no 2D perovskite formation was observed at the buried interfaces of M2 and M1. In M1, an amorphous phase was detected near the SnO2 interface, suggesting that it may act as a rapid degradation pathway for the perovskite solar cell due to the rapid absorption of water and oxygen. Observations through Fig. 5 a to c show that the NH4 of the present invention + -Provides a key basis for the formation of 2D-3D mixed perovskite phases at the SnO2 interface and for improving the stability and performance of solar cells through this.

[0119] Figure 6 shows the results of photoluminescence (PL) measurements at the SnO2 and perovskite interfaces of M1, M2, and M3. In M3, the formation of OA2PbI4 two-dimensional perovskite was confirmed from the emission peak around 525 nm. In M1 and M2, no peak due to OA2PbI4 was observed.

[0120] Figure 7 shows the results of scanning electron microscope (SEM) measurements of the perovskite surfaces of M1, M2, and M3. It can be confirmed that the crystallinity of the perovskite is more pronounced in M3.

[0121] Figure 8 shows the results of X-ray diffraction (XRD) measurements of the perovskite surfaces of M1, M2, and M3. The crystallinity of M2 and M3 in all directions was improved compared to M1. Among them, the highest crystallinity was confirmed in M3. This confirms that the deformation of the interface between SnO2 and perovskite affects the perovskite surface. In particular, it can be confirmed that the delta phase, not the perovskite phase, disappears in M3. This is because the NH4PbI3 in the electron transport layer and the perovskite interface is NH4. + After being replaced by OA, the remaining NH4 + Due to the low migration barrier, NH4 diffuses into the perovskite layer, and the diffused NH4 + This is because the formation of delta phase is suppressed by removing defects existing within the perovskite layer.

[0122] Figure 9 shows the results of time-of-flight secondary ion mass spectrometry (TOF-SIMS) measurements of M1 and M2. Through this, OA from the upper part of the perovskite to the interface of SnO2 and perovskite + You can check the movement.

[0123] Fig. 10 shows the evaluation of the photoelectric device characteristics of M1 (left), M2 (middle), and M3 (right). The upper graph of Fig. 10 is a current-voltage curve, and the solid line and the dotted line represent the measurement results of forward scan (FS) and reverse scan (RS), respectively. Tables 2, 3, and 4 below summarize the evaluation results of the photoelectric device characteristics of M1, M2, and M3, respectively. The conversion efficiency (PCE) value of M3 was 23.78%, which was the highest compared to M1 (22.97%) and M2 (20.15%). In addition, the device stability of M3 was the highest. The lower graph of Fig. 10 is a current density and PCE graph over time. M1 is V max : As measured for 1.01 V, the initial measured value is J Vmax : 22.32 mA / cm 2 , PCE: 22.53%, and the final measurement value is J Vmax : 20.53 mA / cm 2 , PCE: 21.01%. M2 is V max : The measured value is for 0.910 V, and the initial measured value is J Vmax : 22.33 mA / cm 2 , PCE: 20.91%, and the final measurement value is J Vmax : 20.68 mA / cm 2 , PCE: 19.50%. M3 is V max : As measured at 1.03 V, the initial measured value is J Vmax : 23.73 mA / cm 2 , PCE: 24.32%, and the final measurement value is J Vmax : 23.72 mA / cm 2 , PCE: 24.31%.

[0124] PCE (%)V OC (V)FFJ SC(mA / cm 2 )FS22.971.1700.80224.48RS21.961.1650.76924.51

[0125] PCE (%)V OC (V)FFJ SC (mA / cm 2 )FS20.151.0370.77824.98RS20.301.0740.75625.01

[0126] PCE (%)V OC (V)FFJ SC (mA / cm 2 )FS23.781.1710.82124.74RS24.371.1710.84024.78

[0127] Table 5 below shows the average device characteristic evaluation values ​​obtained after fabricating 28 samples for the M1, M2, and M3 structures. It can be confirmed that the conversion efficiency value is the highest at 23.79% in M3.

[0128] V OC (V)PCE (%)FF (%)J SC (mA / cm 2 )M11.125 ± 0.01821.69 ± 0.5279.10 ± 1.2724.38 ± 0.12M21.035 ± 0.02019.44 ± 0.9275.66 ± 3.4024.83 ± 0.20M31.165 ± 0.00823.79 ± 0.3182.70 ± 0.7424.70 ± 0.14

[0129] Figure 11 shows the results of a long-term stability test of devices M1, M2, and M3. M3 maintains a PCE value of 91.87% even after 2000 hours, confirming its excellent long-term stability.

[0130] The above description of the present invention is for illustrative purposes only, and those skilled in the art will readily appreciate that the present invention can be readily modified into other specific forms without altering the technical spirit or essential characteristics of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single entity may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined manner.

[0131] The scope of the present invention is indicated by the claims described below rather than the detailed description above, and all changes or modifications derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

Claims

1. A first passivation layer comprising an ammonium salt; An electron transport layer formed on the first passivation layer and including a metal oxide; A perovskite layer formed on the electron transport layer; and A second passivation layer formed on the perovskite layer and including a compound represented by the following chemical formula 1 As a perovskite photovoltaic device comprising: Comprising a two-dimensional perovskite at the interface between the electron transport layer and the perovskite layer, Perovskite photovoltaic devices: [Chemical Formula 1] R 1 NH3X 1 , In the above chemical formula 1, R 1 Silver C 5-20 is an alkyl group, and X 1 is F, Cl, Br, or I.

2. In paragraph 1, The above ammonium salts are NH4Cl (ammonium chloride), NH4Br (ammonium bromide), NH4I (ammonium iodide), NH4F (ammonium fluoride), NH4NO3 (ammonium nitrate), (NH4)2CO3 (ammonium carbonate), NH4HCO3 (ammonium bicarbonate), (NH4)2SO4 (ammonium sulfate), (NH4)2S2O8 (ammonium persulfate), NH4HSO3 (ammonium bisulfite), NH4HSO4 (ammonium bisulfate), NH4ClO4 (ammonium perchlorate), CH3COONH4 (ammonium acetate), C6H5COONH4 (ammonium benzoate), NH4H2PO4 (ammonium dihydrogen phosphate), (NH4)2HPO4 (ammonium hydrogen phosphate), A perovskite photovoltaic device comprising at least one selected from NH4SCN (ammonium thiocyanate), NH4BF4 (ammonium tetrafluoroborate), and NH4PF6 (ammonium hexafluorophosphate).

3. In paragraph 1, A perovskite photovoltaic device wherein the above two-dimensional perovskite is formed by self-assembly.

4. In paragraph 1, The above two-dimensional perovskite comprises a compound represented by the following chemical formula 3, a perovskite photovoltaic device: [Chemical Formula 3] (R 1 NH3)2MX 1 4, In the above chemical formula 3, R 1 Silver C 5-20 is an alkyl group, M is Pb, Sn, Cu, Ni, Co, Fe, Mn, Pd, Cd, Ge, Cs, Eu, or a combination thereof, and X 1 is F, Cl, Br, or I.

5. In paragraph 1, A perovskite photovoltaic device, wherein the above two-dimensional perovskite comprises OA2PbI4.

6. In paragraph 1, The above metal oxides are SnO2, TiO2, ZnO, WO3, RuO2, La x Sr 1-x CoO3, La x Sr 1-x A perovskite photovoltaic device comprising at least one selected from MnO3, BaSnO3, and LaNiO3, wherein 0 < x ≤ 0.

5.

7. In paragraph 5, A perovskite photovoltaic device, wherein the C 1s X-ray photoelectron spectroscopy (XPS) spectrum of the interface between the electron transport layer and the perovskite layer exhibits a peak detected at 291 eV to 294 eV by the two-dimensional OA2PbI4.

8. In paragraph 1, A perovskite photovoltaic device further comprising a substrate, a first electrode, a hole transport layer, and / or a second electrode.

9. Forming a first passivation layer containing an ammonium salt on the first electrode; Forming an electron transport layer including a metal oxide on the first passivation layer; Forming a perovskite layer on the electron transport layer; and Forming a second passivation layer comprising a compound represented by the following chemical formula 1 on the perovskite layer A method for manufacturing a perovskite photovoltaic device, comprising: A method for manufacturing a perovskite photoelectric device, wherein a two-dimensional perovskite is formed by self-assembly at the interface between the electron transport layer and the perovskite layer: [Chemical Formula 1] R 1 NH3X 1 , In the above chemical formula 1, R 1 Silver C 5-20 is an alkyl group, and X 1 is F, Cl, Br, or I.

10. In paragraph 9, The above ammonium salts are NH4Cl (ammonium chloride), NH4Br (ammonium bromide), NH4I (ammonium iodide), NH4F (ammonium fluoride), NH4NO3 (ammonium nitrate), (NH4)2CO3 (ammonium carbonate), NH4HCO3 (ammonium bicarbonate), (NH4)2SO4 (ammonium sulfate), (NH4)2S2O8 (ammonium persulfate), NH4HSO3 (ammonium bisulfite), NH4HSO4 (ammonium bisulfate), NH4ClO4 (ammonium perchlorate), CH3COONH4 (ammonium acetate), C6H5COONH4 (ammonium benzoate), NH4H2PO4 (ammonium dihydrogen phosphate), (NH4)2HPO4 (ammonium hydrogen phosphate), A perovskite photovoltaic device comprising at least one selected from NH4SCN (ammonium thiocyanate), NH4BF4 (ammonium tetrafluoroborate), and NH4PF6 (ammonium hexafluorophosphate).

11. In paragraph 9, A method for manufacturing a perovskite photoelectric device, wherein the two-dimensional perovskite comprises a compound represented by the following chemical formula 3: [Chemical Formula 3] (R 1 NH3)2MX 1 4, In the above chemical formula 3, R 1 Silver C 5-20 is an alkyl group, M is Pb, Sn, Cu, Ni, Co, Fe, Mn, Pd, Cd, Ge, Cs, Eu, or a combination thereof, and X 1 is F, Cl, Br, or I.

12. In paragraph 9, The above metal oxides are SnO2, TiO2, ZnO, WO3, RuO2, La x Sr 1-x CoO3, La x Sr 1-x A method for manufacturing a perovskite photovoltaic device, comprising at least one selected from MnO3, BaSnO3 and LaNiO3, wherein 0 < x ≤ 0.

5.

13. In paragraph 9, A method for manufacturing a perovskite photovoltaic device, wherein forming the first passivation layer comprises applying a first passivation solution containing the ammonium salt.

14. In paragraph 13, A method for manufacturing a perovskite photovoltaic device, wherein the concentration of the ammonium salt in the first passivation solution is 1 mM to 1000 mM.

15. In paragraph 9, A method for manufacturing a perovskite photovoltaic device, wherein forming the second passivation layer comprises applying a second passivation solution containing a compound represented by the chemical formula 1.

16. In paragraph 15, A method for manufacturing a perovskite photoelectric device, wherein the concentration of the compound represented by the chemical formula 1 in the second passivation solution is 1 mM to 1000 mM.

17. In paragraph 9, A method for manufacturing a perovskite photovoltaic device, further comprising performing UV ozone treatment on each of the first passivation layer, the electron transport layer, and the second passivation layer after forming them.

18. In paragraph 17, A method for manufacturing a perovskite photovoltaic device, wherein the above UV ozone treatment is performed for 1 to 100 minutes.

Images