Patent Application
20240081143
The present disclosure relates to a method of preparing perovskite using an anti-solvent evaporation-controlled method and perovskite prepared thereby.
An organic-inorganic metal halide perovskite material absorbs light in a wide wavelength band including a visible light range and has high carrier mobility and low trap density. Thus, it has received a lot of attention as a material of electronic devices including high-efficiency solar cells. For example, methylammonium (MA, CH3NH3) lead iodide (MAPbI3) perovskite has the advantage of serving as an absorber layer of a high-efficiency solar cell with appropriate band gap energy, high absorption coefficient, and long-distance bipolar photocarrier diffusion. Also, the organic-inorganic metal halide perovskite is crystallized by self-assembly and thus can be prepared by a low-cost solution process. However, when the organic-inorganic metal halide perovskite is prepared by the solution process, the crystallization rate is very high. Therefore, it is difficult to form a uniform film, and the formed phase is widely distributed.
Meanwhile, applying an anti-solvent that does not dissolve perovskite in a solution process but selectively dissolves a solvent of a precursor solution has been known as a method for forming a uniform perovskite film. However, it has been known that the anti-solvent process accelerates the crystallization of perovskite in a localized area, and thus, a finally synthesized perovskite material has a wide phase distribution.
Korean Patent Laid-open Publication No. 10-2018-0096044
The present disclosure relates to a method of preparing perovskite using an anti-solvent evaporation-controlled method and perovskite prepared thereby.
However, problems to be solved by the present disclosure are not limited to the above-described problems, and although not described herein, other problems to be solved by the present disclosure can be clearly understood by those skilled in the art from the following descriptions.
A first aspect of the present disclosure provides a method of preparing perovskite using an anti-solvent evaporation-controlled method, including: a precursor solution applying process of applying a perovskite precursor solution onto a substrate; and an anti-solvent applying process of applying an anti-solvent onto the applied perovskite precursor solution, in the precursor solution applying process, temperatures of the substrate and the perovskite precursor solution are in the range of ±20° C. of the boiling point of the anti-solvent.
A second aspect of the present disclosure provides a perovskite prepared by the method according to the first aspect.
A third aspect of the present disclosure provides a light emitting diode including perovskite according to the second aspect as an emission layer.
In a method of preparing perovskite using an anti-solvent evaporation-controlled method according to embodiments of the present disclosure, temperatures of a substrate and a perovskite precursor solution are set to the range of ±20° C. of the boiling point of the anti-solvent. Thus, the evaporation rate of the anti-solvent on the applied perovskite precursor solution can be uniformly controlled and the crystallization rate can be uniformly controlled over the entire range on the applied perovskite precursor solution.
Perovskite prepared using an anti-solvent evaporation-controlled method according to embodiments of the present disclosure has a quasi-two dimensional profile by controlling temperatures of a substrate and a perovskite precursor solution to be in the range of ±20° C. of the boiling point of the anti-solvent. Thus, the perovskite has a quasi-two dimensional profile with a narrow phase distribution and has a smooth surface morphology.
Due to the anti-solvent evaporation, the perovskite prepared by the anti-solvent evaporation-controlled method according to embodiments of the present disclosure can have a quasi-two dimensional profile with a narrow phase distribution regardless of the kind of material.
Due to the quasi-two dimensional profile with a narrow phase distribution, the perovskite prepared by the anti-solvent evaporation-controlled method according to embodiments of the present disclosure can emit clear blue light with high efficiency when applied to a light emitting diode.
Hereinafter, embodiments and examples of the present disclosure will be described in detail with reference to the accompanying drawings so that the present disclosure may be readily implemented by those skilled in the art. However, it is to be noted that the present disclosure is not limited to the embodiments and examples but can be embodied in various other ways. In drawings, parts irrelevant to the description are omitted for the simplicity of explanation, and like reference numerals denote like parts through the whole document.
Through the whole document, the term “connected to” or “coupled to” that is used to designate a connection or coupling of one element to another element includes both a case that an element is “directly connected or coupled to” another element and a case that an element is “electronically connected or coupled to” another element via still another element.
Through the whole document, the term “on” that is used to designate a position of one element with respect to another element includes both a case that the one element is adjacent to the other element and a case that any other element exists between these two elements.
Further, through the whole document, the term “comprises or includes” and/or “comprising or including” used in the document means that one or more other components, steps, operation and/or existence or addition of elements are not excluded in addition to the described components, steps, operation and/or elements unless context dictates otherwise.
Through the whole document, the term “about or approximately” or “substantially” is intended to have meanings close to numerical values or ranges specified with an allowable error and intended to prevent accurate or absolute numerical values disclosed for understanding of the present disclosure from being illegally or unfairly used by any unconscionable third party.
Through the whole document, the term “step of” does not mean “step for”.
Through the whole document, the term “combination(s) of” included in Markush type description means mixture or combination of one or more components, steps, operations and/or elements selected from a group consisting of components, steps, operation and/or elements described in Markush type and thereby means that the disclosure includes one or more components, steps, operations and/or elements selected from the Markush group.
Through the whole document, a phrase in the form “A and/or B” means “A or B, or A and B”.
Through the whole document, the term “alkyl” or “alkyl group” may individually include linear or branched alkyl groups having 1 to 12 carbon atoms, 1 to 10 carbon atoms, 1 to 8 carbon atoms, or 1 to 5 carbon atoms, and all the possible isomers thereof. For example, the alkyl or alkyl group may individually include methyl group (Me), ethyl group (Et), n-propyl group (nPr), iso-propyl group (iPr), n-butyl group (nBu), iso-butyl group (iBu), tert-butyl group (tBu), sec-butyl group (sBu), n-pentyl group (nPe), iso-pentyl group (iPe), sec-pentyl group (sPe), tert-pentyl group (tPe), n-hexyl group, iso-hexyl group, heptyl group, 4,4-dimethyl pentyl group, octyl group, 2,2,4-trimethyl pentyl group, nonyl group, decyl group, undecyl group, dodecyl group, and isomers thereof, but may not be limited thereto.
In the following description, exemplary embodiments of the present disclosure will be described in detail, but the present disclosure may not be limited thereto.
A first aspect of the present disclosure provides a method of preparing perovskite using an anti-solvent evaporation-controlled method, including: a precursor solution applying process of applying a perovskite precursor solution onto a substrate; and an anti-solvent applying process of applying an anti-solvent onto the applied perovskite precursor solution, in the precursor solution applying process, temperatures of the substrate and the perovskite precursor solution are in the range of ±20° C. of the boiling point of the anti-solvent.
In an embodiment of the present disclosure, the anti-solvent may include at least one selected from toluene, chlorobenzene and chloroform, but may not be limited thereto.
In an embodiment of the present disclosure, the anti-solvent is brought into contact with the precursor solution, and, thus, the solubility of the precursor solution decreases, which serves to accelerate the crystallization of perovskite.
In an embodiment of the present disclosure, an evaporation rate of the anti-solvent on the applied perovskite precursor solution can be uniformly controlled by setting the temperatures of the substrate and the perovskite precursor solution to the range of ±20° C. of the boiling point of the antisolvent. Specifically, the temperatures of the substrate and the perovskite precursor solution may be in the range of about ±20° C., about ±18° C., about ±16° C., about ±14° C., about ±12° C., about ±10° C., about ±9° C., about ±8° C., about ±7° C., about ±6° C., about ±5° C., about ±4° C., about ±3° C., about ±2° C., about ±1° C., or about ±0.5° C. of the boiling point of the anti-solvent. For example, if the anti-solvent is toluene, the temperatures of the substrate and the perovskite precursor solution may be in the range of about 90° C. to about 130° C., about 92° C. to about 128° C., about 94° C. to about 126° C., about 96° C. to about 124° C., about 98° C. to about 122° C., about 100° C. to about 120° C., about 101° C. to about 119° C., about 102° C. to about 118° C., about 103° C. to about 117° C., about 104° C. to about 116° C., about 105° C. to about 115° C., about 106° C. to about 114° C., about 107° C. to about 113° C., about 108° C. to about 112° C., about 109° C. to about 111° C., or about 109.5° C. to about 110.5° C.
In an embodiment of the present disclosure, the evaporation rate of the anti-solvent applied on the perovskite precursor solution is uniformly controlled. Thus, the crystallization rate can be uniformly controlled over the entire range on the applied perovskite precursor solution. The crystallization rate on a surface of the applied perovskite precursor solution may match the crystallization rate on the interface between the applied perovskite and the substrate.
In an embodiment of the present disclosure, the precursor solution applying process may be performed by at least one selected from a spin-coating method, a spray-coating method, and a dip-coating method, but may not be limited thereto.
In an embodiment of the present disclosure, the anti-solvent applying process may be performed by at least one selected from a spin-coating method, a spray-coating method, and a dip-coating method, but may not be limited thereto. For example, if the precursor solution applying process and the anti-solvent applying process are performed by spin-coating, the precursor solution is applied onto the substrate, followed by spin-coating. Before spin-coating is completed, the anti-solvent is applied onto the precursor solution. Thus, a series of processes of spin-coating are completed.
In an embodiment of the present disclosure, the method may further include an annealing process after the anti-solvent applying process.
In an embodiment of the present disclosure, quasi-two dimensional perovskite crystals in which the number of unit cell (n) is an integer of 1 to 3 may be obtained with a ratio of about 95% or more of all crystals by the method of preparing perovskite. Specifically, quasi-two dimensional perovskite crystals in which the number of unit cell (n) is an integer of 1 to 3 may be obtained with a ratio of about 95% or more, about 96% or more, about 97% or more, about 98% or more, or about 99% or more of all crystals by the method of preparing perovskite. A conventional technique of simply applying an anti-solvent onto a perovskite precursor solution accelerates the crystallization of perovskite in a localized area on the precursor solution. Thus, a finally synthesized perovskite material has a wide phase distribution. However, according to the present disclosure, the evaporation rate of the anti-solvent applied on the precursor solution is uniformly controlled by the method of preparing perovskite using the anti-solvent evaporation-controlled method. Thus, the crystallization rate can be uniformly controlled over the entire range on the coated perovskite precursor solution. Therefore, quasi-two dimensional perovskite crystals in which the number of unit cell (n) is an integer of 1 to 3 can be obtained with a ratio of about 95% or more, about 96% or more, about 97% or more, about 98% or more, or about 99% or more of all crystals.
A second aspect of the present disclosure provides a perovskite prepared by the method according to the first aspect.
In an embodiment of the present disclosure, the perovskite may be represented by the following Chemical Formula 1:
(ANH3)2B(m−1)CmX3m+1 [Chemical Formula 1]
In the Chemical Formula 1, A includes an arylalkyl group or a linear alkyl group having 1 to 10 carbon atoms, B includes at least one selected from RNH3 and Cs, R includes a linear or branched alkyl group having 1 to 10 carbon atoms, C includes at least one metal cation selected from Pb2+, Cu2+, Ni2+, Co2+, Fe2+, Mn2+, Cr2+, Pd2+, Cd2+, Yb2+, Sn2+ and Ge2+, X includes at least one halide anion selected from Cl−, Br− and I−, and m is an integer of 2 or more.
In an embodiment of the present disclosure, the perovskite may be represented by the following Chemical Formula 2:
(ANH3)2B(m−1)PbmX3m+1 [Chemical Formula 2]
In the Chemical Formula 2, A includes an arylalkyl group or a linear alkyl group having 1 to 10 carbon atoms, B includes at least one selected from RNH3 and Cs, R includes a linear or branched alkyl group having 1 to 10 carbon atoms, X includes at least one halide anion selected from Cl−, Br− and I−, and m is an integer of 2 or more.
In an embodiment of the present disclosure, the perovskite may include at least one selected from PEA2CsPb2Br7 (PEA: phenethyl ammonium), BA2CsPb2Br7 (BA: benzyl ammonium), nHA2CsPb2Br7 (nHA: n-hexyl ammonium), PEA2CsPb2I7, PEA2MAPb2Br7 (MA: methyl ammonium), and iPA2CsPb2Br7 (iPA: isopropyl ammonium), but may not be limited thereto.
In an embodiment of the present disclosure, the perovskite may be crystallized at a uniform rate over the entire range on the perovskite precursor solution. Thus, the perovskite may have a smooth surface morphology and may have a quasi-two dimensional profile with a narrow phase distribution.
In an embodiment of the present disclosure, the perovskite may have a quasi-two dimensional profile in which the number of unit cell (n) is an integer of 1 to 3.
In an embodiment of the present disclosure, the perovskite may have a maximum photoluminescence peak at a wavelength range of about 440 nm to about 500 nm. Specifically, the perovskite may have a maximum photoluminescence peak at a wavelength range of about 440 nm to about 500 nm, about 445 nm to about 500 nm, about 450 nm to about 500 nm, about 455 nm to about 500 nm, about 460 nm to about 500 nm, about 465 nm to about 500 nm, about 440 nm to about 490 nm, about 445 nm to about 490 nm, about 450 nm to about 490 nm, about 455 nm to about 490 nm, about 460 nm to about 490 nm, about 465 nm to about 490 nm, about 440 nm to about 480 nm, about 445 nm to about 480 nm, about 450 nm to about 480 nm, about 455 nm to about 480 nm, about 460 nm to about 480 nm, about 465 nm to about 480 nm, about 440 nm to about 475 nm, about 445 nm to about 475 nm, about 450 nm to about 475 nm, about 455 nm to about 475 nm, about 460 nm to about 475 nm, about 465 nm to about 475 nm, about 440 nm to about 470 nm, about 445 nm to about 470 nm, about 450 nm to about 470 nm, about 455 nm to about 470 nm, about 460 nm to about 470 nm, about 465 nm to about 470 nm, about 440 nm to about 467 nm, about 445 nm to about 467 nm, about 450 nm to about 467 nm, about 455 nm to about 467 nm, about 460 nm to about 467 nm, or about 465 nm to about 467 nm.
In an embodiment of the present disclosure, the perovskite may have a full width at half maximum of the maximum photoluminescence peak of about 20 nm or less. Specifically, the perovskite may have a full width at half maximum of the maximum photoluminescence peak of about 20 nm or less, about 19 nm or less, about 18 nm or less, about 17 nm or less, about 16 nm or less, about 15 nm or less, or about 14 nm or less.
A third aspect of the present disclosure provides a light emitting diode including perovskite according to the second aspect as an emission layer.
In an embodiment of the present disclosure, the light emitting diode may include a substrate, a first electrode layer formed on the substrate, a hole injection layer formed on the first electrode layer, an emission layer including the perovskite and formed on the hole injection layer, an electron transport layer formed on the emission layer, and a second electrode layer formed on the electron transport layer, but may not be limited thereto.
In an embodiment of the present disclosure, the light emitting diode may include, for example, an indium tin oxide (ITO) substrate, a poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) layer formed on the ITO substrate, a poly(9-vinylcarbazole) (PVK) layer formed on the PEDOT:PSS layer, a perovskite layer formed on the PVK layer, a polymethyl methacrylate (PMMA) layer formed on the perovskite layer, a 2,2′,2″-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole (TPBi) layer formed on the PMMA layer, and an LiF/Al layer formed on the TPBi layer, but may not be limited thereto.
In an embodiment of the present disclosure, the light emitting diode may exhibit stable emission characteristics due to the perovskite layer prepared by the anti-solvent evaporation-controlled method. Specifically, the stable emission characteristics of the light emitting diode may be manifested by the appearance of a peak of an electroluminescence spectrum (EL spectrum) in a predetermined wavelength band.
Detailed descriptions on the second aspect and the third aspect of the present disclosure, which overlap with those on the first aspect of the present disclosure, are omitted hereinafter, but the descriptions of the first aspect of the present disclosure may be identically applied to the second aspect and the third aspect of the present disclosure, even though they are omitted hereinafter.
Hereinafter, example embodiments are described in more detail by using Examples, but the present disclosure may not limited to the Examples.
1) Preparation of Perovskite (PE2CsPb2Br2) precursor solution
A perovskite precursor solution was prepared by dissolving stoichiometric amounts of lead(II) bromide (PbBr2), 2-phenylethylammonium bromide (PEABr), and cesium bromide (CsBr) in a solvent, dimethyl sulfoxide (DMSO). A molar concentration of PbBr2 in the perovskite precursor solution was 0.03 M. To improve the crystallinity of a perovskite thin film, 20 mg/mL of n-propylammonium bromide (nPABr) was added to the precursor solution. The precursor solution was vigorously stirred at 110° C. for 20 minutes and then filtered through a polytetrafluoroethylene syringe filter (0.2 μm).
2) Fabrication of Perovskite Thin Film Using Anti-Solvent Evaporation-Controlled Method
The perovskite precursor solution was heated to 110° C. and then dropped onto a substrate heated to 110° C., immediately followed by spin-coating (4000 rpm, 20 seconds). An anti-solvent, toluene, (150 μL) was dropped during spin-coating. After spin-coating was completed, the thin film was annealed (100° C., 4 minutes). Further, to investigate the effect of temperatures of the precursor solution and the substrate on the evaporation rate of the anti-solvent, the temperatures of the precursor solution and the substrate were set to 20° C., 65° C., and 155° C. and an additional perovskite thin film was fabricated.
3) Fabrication of LED
PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) was spin-coated (5000 rpm, 40 seconds) onto a previously cleaned ITO (indium tin oxide) substrate and then annealed (150° C., 20 minutes). Poly(9-vinylcarbazole) (PVK) (3 mg/mL) dissolved in chlorobenzene was spin-coated (4000 rpm, 35 seconds) on the PEDOT:PSS layer and then annealed (100° C., 20 minutes). Thereafter, to reduce a barrier to hole injection, perfluorinated resin solution (PFI) (0.1 wt %) mixed with isopropyl alcohol was spin-coated (4000 rpm, 30 seconds) and a PVK:PFI layer was formed. Then, a perovskite thin film was formed using an anti-solvent evaporation-controlled method. A BCP (bathocuproine) layer (10 nm), a TPBi (2,2′,2″-(1,3,5-Benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)) layer (40 nm), an LiF layer (2 nm), and an Al layer (70 nm) were sequentially deposited on the perovskite layer by thermal evaporation (pressure<1.0×10−6 torr) (
A perovskite thin film was fabricated using the anti-solvent evaporation-controlled method in the same manner as in Example 1. Perovskite thin films were formed of perovskite materials, BA2CsPb2Br7, nHA2CsPb2Br7, PEA2CsPb2I7, and iPA2CsPb2Br7. Also, light emitting diodes including BA2CsPb2Br7, nHA2CsPb2Br7, PEA2CsPb2I7, and iPA2CsPb2Br7 perovskite thin films as perovskite thin films, respectively, were fabricated in the same manner as in Example 1.
1) Fabrication of Perovskite Thin Film Using Hot-Casting Method
Each of perovskite (PEA2CsPb2Br7, BA2CsPb2Br7, nHA2CsPb2Br7, and iPA2CsPb2Br7) precursor solutions used in Example 1 and Example 2 was heated and then dropped onto a substrate heated to 110° C., immediately followed by spin-coating (4000 rpm, 20 seconds) to fabricate a perovskite thin film using a hot casting method.
2) Fabrication of LED
The perovskite thin film fabricated using the hot casting method was fabricated into an LED in the same manner as in Example 1.
1) Fabrication of perovskite thin film using anti-solvent method
Each of perovskite (PEA2CsPb2Br7, BA2CsPb2Br7, nHA2CsPb2Br7, and iPA2CsPb2Br7) precursor solutions used in Example 1 and Example 2 was cooled to room temperature and then spin-coated (4000 rpm, 20 seconds). An anti-solvent, toluene, (150 μL) was dropped during spin-coating to fabricate a perovskite thin film using an anti-solvent method.
2) Fabrication of LED
The perovskite thin film fabricated using the anti-solvent method was fabricated into an LED in the same manner as in Example 1.
1) By using the perovskite (PEA2CsPb2Br7) precursor solution of Example 1, absorption and emission spectra of perovskite thin films fabricated at different temperatures of the solution and the substrate were measured (
2) According to the measurement result of absorption and emission spectra of perovskite thin films (PEA2CsPb2Br7) fabricated in Example 1 (anti-solvent evaporation-controlled method), Comparative Example 1 (hot-casting method) and Comparative Example 2 (anti-solvent method), it was confirmed that perovskite synthesized by the anti-solvent evaporation-controlled method exhibited the narrowest phase distribution (
3) Absorption and emission spectra of perovskite (BA2CsPb2Br7, nHA2CsPb2Br7, PEACsPb2I7, and iPA2CsPb2Br7) thin films fabricated in Example 1 (anti-solvent evaporation-controlled method), Comparative Example 1 (hot-casting method) and Comparative Example 2 (anti-solvent method) were measured (
XRD of perovskite (PEA2CsPb2Br) thin films fabricated in Example 1 (anti-solvent evaporation-controlled method), Comparative Example 1 (hot-casting method) and Comparative Example 2 (anti-solvent method) were measured (
Atomic force microscopy (AFM) images of perovskite (PEA2CsPb2Br7) thin films fabricated in Example 1 (anti-solvent evaporation-controlled method), Comparative Example 1 (hot-casting method) and Comparative Example 2 (anti-solvent method) were measured to obtain surface images and phase contrast images (
1) Characteristics of perovskite (PEA2CsPb2Br7)-based LEDs fabricated in Example 1 (anti-solvent evaporation-controlled method), Comparative Example 1 (hot-casting method) and Comparative Example 2 (anti-solvent method) were analyzed (
The following Table 1 shows characteristics of the perovskite (PEA2CsPb2Br7)-based LEDs fabricated in Example 1 (anti-solvent evaporation-controlled method), Comparative Example 1 (hot-casting method) and Comparative Example 2 (anti-solvent method).
2) Characteristics of perovskite (BA2CsPb2Br7, nHA2CsPb2Br7, and iPA2CsPb2Br7)-based LEDs fabricated in Example 2 (anti-solvent evaporation-controlled method), Comparative Example 1 (hot-casting method) and Comparative Example 2 (anti-solvent method) were analyzed (
The above description of the example embodiments is provided for the purpose of illustration, and it would be understood by those skilled in the art that various changes and modifications may be made without changing technical conception and essential features of the example embodiments. Thus, it is clear that the above-described example embodiments are illustrative in all aspects and do not limit the present disclosure. For example, each component described to be distributed can be implemented in a combined manner.
The scope of the inventive concept is defined by the following claims and their equivalents rather than by the detailed description of the example embodiments. It shall be understood that all modifications and embodiments conceived from the meaning and scope of the claims and their equivalents are included in the scope of the inventive concept.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10-2021-0062824 | May 2021 | KR | national |
This application is a continuation of PCT Application No. PCT/KR2021/012600, filed on Sep. 15, 2021, which claims priority to Korean Patent Applications No. 10-2021-0062824 filed on May 14, 2021, both of which are hereby incorporated by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/KR2021/012600 | Sep 2021 | US |
| Child | 18507186 | US |
