Patent Application
20250194428
This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0179146, filed on Dec. 11, 2023, the disclosure of which is incorporated herein by reference in its entirety.
The present invention relates to a quasi-two-dimensional halide perovskite thin film, and a piezoelectric energy harvester including the same.
Energy harvesting refers to the technology of harvesting energy generated from natural energy sources such as solar light, vibration, heat, and wind power and converting it into electrical energy.
Such energy harvesting is attracting attention as an eco-friendly energy utilization technology that can maintain the stability, security, and sustainability of energy supply and reduce environmental pollution because it enables electrical energy to be obtained directly from nature.
An organo metallic halide perovskite (OMHPV) compound is a material with a structure represented by ABX3, wherein A is an organic cation, B is a metallic cation such as Pb or Sn, X is a halogen anion, and B and X form an octahedron called BX6. In addition, B is located at the center of the octahedron formed by X located at the corners, the octahedron forms a three-dimensional network with all corners connected to each other, and A is a material whose structure balances the charge of the entire network with large cations that fill the empty holes created by adjacent octahedra within the three-dimensional structure. The organic cations used in this material are mostly methylammonium cations (CH3NH3+, or MA+), but may also be formamidinium cations (HC(NH2)2+, or FA+). B is a divalent metal, such as Pb, Sn, or Cu.
Such OMHPV compounds have a wide range of applications due to their excellent electrical conductivity, excellent charge mobility, and excellent optical properties, and have various characteristics including long lifetime, high absorption wavelength spectra due to small energy band gaps, and wide charge-carrier diffusion lengths. In addition, these OMHPV compounds are attracting attention as promising materials for renewable energy applications because they have the advantages of being economical in material price, being able to be produced as solutions, having low production costs, and being able to be produced through low-temperature processes. In particular, research is underway on the use of these compounds as light absorbers for perovskite solar cells.
Meanwhile, research on the optical properties of quasi-two-dimensional halide perovskites, which have a different structure from the above-described three-dimensional halide perovskites and have a specific number (n) of inorganic material layers, is being reported. However, studies on the mechanical piezoelectricity of such a quasi-two-dimensional halide perovskite are insufficient.
The present invention is directed to controlling and improving the mechanical piezoelectricity of a quasi-two-dimensional halide perovskite.
According to an aspect of the present invention, the present invention provides a quasi-two-dimensional halide perovskite thin film, in which the halide perovskite has the chemical formula X2An−1BnY3n+1, X is an organic or inorganic material, A is at least one of methylammonium (MA), formamidinium (FA), and cesium (Cs), B is a metallic cation, Y is a halogen anion, n is a natural number greater than or equal to 2 and less than the natural number k, and as the value of n increases, the piezoelectricity increases.
According to another aspect of the present invention, the present invention provides a piezoelectric energy harvester, which includes the quasi-two-dimensional halide perovskite thin film.
According to the present invention, energy-efficient materials for the production of wearable pressure sensors can be developed by designing a novel two-dimensional piezoelectric composition-based energy harvesting device.
In addition, according to the present invention, the device of the present invention is free from environmental constraints due to its high moisture stability, unlike conventional three-dimensional halide-based devices.
In addition, according to the present invention, the development of wearable pressure sensors that meet market demands is possible based on controlled piezoelectric properties by controlling the number of layers of a quasi-two-dimensional halide perovskite.
The above objects, other objects, features and advantages of the present invention will be easily understood through the following exemplary embodiments relating to the accompanying drawings. The present invention is not limited to exemplary embodiments to be described below, but may be embodied in other forms. Rather, the embodiments presented herein are provided such that the technical idea can be fully conveyed to those of ordinary skill in the art.
In description of each drawing, like numerals denote like elements. In the accompanying drawings, the dimensions of structures are enlarged from the actual size for the clarity of the present invention. The terms “first” and “second” may be used to describe various components, but the components should not be limited by these terms. The terms are used only to distinguish one component from another component. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. Singular expressions include plural referents unless the context clearly indicates otherwise.
In the specification, it should be understood that the term “comprise,” “include,” or “have” is intended to indicate the presence of a characteristic, number, step, action, component or part described in the specification, or a combination thereof, but does not preclude the possibility of the presence or addition of one or more other characteristics, numbers, steps, actions, components, parts or a combination thereof. In addition, when apart of a layer, film, region or plate is disposed “on” another part, this includes not only a case in which the one part is disposed “directly on” the other part, but also a case in which a third part is interposed therebetween. In contrast, when a part of a layer, film, region or plate is disposed “under” another part, this includes not only a case in which the one part is disposed “directly under” the other part, but also a case in which a third part is interposed therebetween. In addition, in this application, “on” may include not only a case where something is disposed on an upper part of something else but also a case where something is disposed on a lower part of something else.
Unless otherwise specified, all numbers, values, and/or expressions that express components, reaction conditions, polymer compositions, and the amount of a mixture, used in the specification, are to be understood as being modified in all instances by the term “approximately” since these numbers are approximations that reflect the various uncertainties of measurement occurring to obtain these values, among other things. In addition, when a numerical range is disclosed in this description, such range is continuous and, unless indicated otherwise, includes all values from the minimum value to the maximum value. Furthermore, when such a range refers to an integer, unless otherwise indicated, all integers from the minimum value up to the maximum value are included.
According to one aspect of the present invention, as a quasi-two-dimensional halide perovskite thin film, a quasi-two-dimensional halide perovskite thin film in which the halide perovskite has the chemical formula X2An−1BnY3n+1 (n is a natural number greater than or equal to 2 and less than the natural number k) is provided. Here, X is an organic or inorganic material, A is at least one of methylammonium (MA), formamidinium (FA), and cesium (Cs), B is a metallic cation, and Y is a halogen anion.
According to one embodiment of the present invention, X may include at least one of propylammonium (PA), butylammonium (BA), and hexylammonium (HA). Referring to
According to one embodiment of the present invention, B may include at least one of Pb and Sn.
According to one embodiment of the present invention, Y may include at least one of I, Br, and Cl (halide anions).
According to one embodiment of the present invention, k may be any natural number from 5 to 10.
According to one embodiment of the present invention, as the value of n in the quasi-two-dimensional halide perovskite thin film increases, piezoelectricity may increase. For example, when k is 6, the piezoelectricity of the quasi-two-dimensional halide perovskite thin film may be increased from n=2 to n=5.
The present invention will be described more specifically through the following experimental examples. The following experimental examples are merely examples to help understand the present invention, and the scope of the present invention is not limited thereto.
PA2MAn−1PbnI3n+1 (n=1 to 6) and MAPbI3 precursor solutions were prepared by adding n-propyl ammonium iodide (PAI, Greatcell Solar Materials, Australia), methyl ammonium iodide (MAI, 99.9%, Greatcell Solar Materials, Australia), and lead iodide (PbI2, 99.99%, TCI, Japan) in a mixed solvent (at a volume ratio of 7:3) of γ-butyrolactone (GBL, 99%, Sigma-Aldrich, USA) and dimethyl sulfoxide (DMSO, anhydrous, 99.9%, Sigma-Aldrich, USA) from a stoichiometric molar ratio based on the fixed concentration of PbI2. Then, the solution was stirred at 70° C. for 5 hours.
Before deposition of the precursor solution, an indium tin oxide (ITO)-coated polyethylene terephthalate (PET) substrate (2.5 cm×2.5 cm) was sonicated in an isopropyl alcohol (IPA, C3H8O, anhydrous, Daejung, Korea) bath for 10 minutes and then surface-treated with O2 (20 sccm) plasma at 100 W for 5 minutes. Subsequently, the prepared solution was spin-coated on ITO/PET at 1000 rpm for 10 seconds, coated at 4000 rpm for 30 seconds, and annealed at 100° C. for 15 minutes. Toluene (C6H5CH3, 99.5%, Duksan, Korea) used as an antisolvent was dropped 10 seconds before spin coating was completed.
To produce a piezoelectric energy harvester, a 50 μm ITO/PEN substrate was coated with a PDMS (SYLGARD 184, Dow Corning, USA) solution consisting of a base monomer containing a 10 wt % curing agent through spin coating at 3000 rpm for 30 seconds, and then precured at 100° C. for 3 minutes. The precured PDMS layer was attached to a PA2MAn−1PbnI3n+1 film and cured again to ensure clean adhesion with no gap between them.
Afterward, the final structure of PEN/ITO/PDMS/PA2MAn−1PbnI3n+1/ITO/PET had Cu wires that were connected to both sides of the exposed ITO and sealed with a polyimide tape.
The surface and cross-sectional microstructures of the quasi-two-dimensional halide film were observed with a field emission scanning electron microscope (FE-SEM, JSM 7001F, JEOL, Japan), operating at an accelerating voltage of 75 kV. PL spectra were obtained at room temperature using a Raman spectrometer (LabRam Aramis, Horiba Jobin Yvon, France) with a 325 nm He—Cd laser source. The crystal structure of the quasi-two-dimensional halide film was examined using a high-resolution X-ray diffractometer (HR-XRD, SmartLab, Rigaku, Japan) irradiating Cu—Kα radiation (λ=1.5418 Å) in the 2θ range of 5 to 50°. The dielectric constant (εr) was obtained as a function of frequency in the range of 102 to 106 Hz using an impedance analyzer (HP 4194A, Hewlett Packard, USA).
The piezoelectric properties of the quasi-two-dimensional halide film were characterized by PFM (Nanoscope V Multimode, Bruker, USA) using conductive Pt/Ir-coated Si cantilever tips. The PR amplitude was measured by scanning the film surface (3 μm×3 μm) with a driving amplitude of 4 V in the lock-in mode at a variable AC voltage (Vac). The effective out-of-plane piezoelectric coefficient (d33,eff) was estimated from the peak amplitude using the relationship Adeflection=d33,eff×Vac/16, where Adeflection is the peak amplitude. The P-E loop was obtained at a frequency of 100 Hz using the dynamic hysteresis method (DHM) based on a triangular pulse.
The harvesting performance was evaluated under cyclic bending at a frequency range of 0.6 to 3.0 Hz and bending strains of 0.6 to 3.0% using a single-axis high-speed fatigue machine (CTLM500, Ceratorq, Korea). The output performance was measured using a nanovoltmeter (Keithley 2182A, ValueTronics, USA) operated with an internal resistance of 10 MΩ, and the output current was determined using a galvanostat system (IviumStat, Ivium Technologies, Netherlands) operated with an internal resistance of 1 MΩ.
Referring to
The n-dependent piezoelectricity of the quasi-two-dimensional halide thin film was examined using PFM.
Specifically, when n=2,
Table 1 below is a table analyzing the data shown in
Table 2 below is a table analyzing the data shown in
Specifically,
Referring to
In addition, referring to
Referring to
Referring to
Although the present invention has been described above with reference to the preferred embodiments thereof, it will be understood by those of ordinary skill in the art that various modifications and changes may be made to the present invention without departing from the spirit and scope of the present invention as set forth in the claims below.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2023-0179146 | Dec 2023 | KR | national |
