KR20160004220A - Perovskite solar cell and preparing method thereof - Google Patents

Abstract

A perovskite solar cell, and a method of manufacturing the perovskite solar cell.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a perovskite solar cell,

The present invention relates to a perovskite solar cell and a method for manufacturing the perovskite solar cell.

Over the past two years, methylammonium lead halide-based perovskite solar cells have made remarkable progress in power conversion efficiencies (PCE). The introduction of CH ₃ NH ₃ PbX ₃ (X = Br, I) by Miyazaka et al. (Miyasaka et al) as a sensitizer in the electrolyte based on the dye-sensitized solar cell structure was recorded as the first perovskite based on photovoltaic cells . However, the perovskite sensitizer was dissolved in the polar liquid electrolyte and a low PCE of 3% to 6% was obtained. The report of long-term durability 9.7% all-solid-state perovskite solar cells has activated research activities. As a result, the PCE has improved rapidly to 15%. The first version of the perovskite solar cell was based on the concept of sensitizer, and a CH ₃ NH ₃ PbI ₃ perovskite nanodot was formed on the TiO ₂ surface. The perovskite itself was found to be able to transfer photo-generated electrons to the TiO ₂ by using an inert electron-blocking Al ₂ O ₃ scaffold. The surface photoresponse concept developed thereafter, and in one implementation, the structure filled with perovskite-mesoporous oxides led to a PCE of 12%. Structural deformation of the nanocrystalline film from the photosensitive to the planar junction is made possible by balancing the electron and hole mobility of the perovskite with a long diffusion length of 1 μm or more.

In the pores of the mesoporous TiO ₂ film, perovskite CH ₃ NH ₃ PbI ₃ With respect to the method for forming, sequential two-step deposition has been proposed to obtain a renewable high-performance perovskite solar cell. PbI ₂ After the solution was spin-coated on the mesoporous TiO ₂ thin film, the PbI ₂ -coated substrate was CH ₃ NH ₃ I Lt; / RTI > Up to 15% PCE was obtained using the two-step deposition method. Perovskite solar cells with vacuum-deposited CH ₃ NH ₃ PbI _{3 - x C x} showed the highest PCE of 15.4%. However, the mean PCE was 12% and the standard deviation was 12.3% ± 2.0%. It is very difficult to measure the exact efficiency of such a planar perovskite device because of the well-known magnetic hysteresis effect of the JV curve. Therefore, a reproducible and effective method for realizing a perovskite photocell having an average PCE of 15% or more and a small standard deviation must be ensured.

Korean Patent Laid-Open No. 10-2003-0073138 discloses a method for preparing a superpowder nanocomposite powder by uniformly dispersing uniformly sized metal oxide nanoparticles having a superparamagnetic property on a ceramic matrix by using ultrasonic spray pyrolysis And a method for economically producing the metal oxide / ceramic nanocomposite powder.

Accordingly, the present invention provides a perovskite solar cell and a method for manufacturing the perovskite solar cell.

However, the problems to be solved by the present invention are not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those skilled in the art from the following description.

According to a first aspect of the present invention, there is provided a method of manufacturing a light emitting device, comprising: forming a recombination preventing layer on a first electrode including a conductive transparent substrate; The recombination layer MX ₂ spin (where, M represents Pb, Sn, Ge, and include those selected from the group consisting of the combinations thereof, and, X is a halogen Im) coating, and the spin-coated MX ₂ Wherein R is a substituted or unsubstituted alkyl group, and when the R is substituted, the substituent is an amino group, a hydroxyl group, a cyano group, a halogen group, a nitro group, or a methoxy group , And X is a halogen) to form a photoactive layer comprising cubic perovskite; Forming a hole transporting layer on the photoactive layer; And forming a second electrode in the hole transporting layer. The present invention also provides a method of manufacturing a perovskite solar cell,

According to a second aspect of the present invention, there is provided a perovskite solar cell manufactured according to the first aspect of the present invention, comprising: a first electrode including a conductive transparent substrate; An anti-recombination layer formed on the first electrode; A photoactive layer including a cubic perovskite represented by the following Chemical Formula 1 formed in the recombination preventing layer; A hole transport layer formed on the photoactive layer; And a second electrode formed on the hole transport layer, wherein the perovskite solar cell comprises:

[Chemical Formula 1]

RMX ₃

Wherein R is a substituted or unsubstituted alkyl group, and when R is substituted, the substituent is an amino group, a hydroxyl group, a cyano group, a halogen group, a nitro group, or a methoxy group, M is Pb, Sn , Ge, and combinations thereof, wherein X is a halogen.

In one embodiment of the present invention, a high efficiency CH ₃ NH ₃ PbI ₃ -based perovskite solar cell is manufactured by a process capable of reproduction by producing perovskite using a two-step spin- can do. Accordingly, the perovskite solar cell produced had an average PCE of about 16%, and the crystal size of the cubic CH ₃ NH ₃ PbI ₃ was controlled by a two-step spin-coating treatment to have a PCE of 17 %. In addition, in the manufacture of perovskite, after spin-coating of MX ₂ , different concentrations of perovskite- The solution was spin-coated cubic CH ₃ NH ₃ PbI ₃ And the crystal size of the cubic perovskite is in the range of 10 < RTI ID = 0.0 > It strongly depends on the concentration. Based on the crystal size control of the cubic perovskite, the present invention provides a photocurrent density of 21.64 mA / cm ² , a PCE of up to 17.01%, an open circuit photovoltage of 1.056 V, The fill factor (FF) can be obtained.

1 is a schematic diagram showing a two-step spin-coating process of a perovskite solar cell in one embodiment of the present invention.
(A) to (e) of Figure 2, according to one embodiment of the invention, each 2-step spin-coating process by mesopores TiO ₂ CH ₃ NH ₃ PbI ₃ grown on the film Cuboid surface (left) and cross section (R) and the SEM image, FIG. In one embodiment of the (f) is present in the 2, CH ₃ NH ₃ according to the concentration I CH ₃ NH ₃ PbI ₃ Figure 2 (g) is a graph of the cubic size distribution of CH ₃ NH ₃ PbI ₃ according to the concentration of CH ₃ NH ₃ I It is a cubic size plot.
(A) and (b) of Figure 3, in one embodiment of the present application, each of 0.032 M (5 mg / mL) CH 3 NH 3 I , and 0.038 M (6 mg / mL) grown from CH ₃ NH ₃ I SEM image of the CH ₃ NH ₃ PbI ₃ cubic.
Figures 4 (a) and 4 (b) illustrate, in one embodiment of the present application, PbI ₂ Surface and cross-sectional SEM images of the coated film.
Figures 5 (a) and 5 (b) show, in an embodiment of the present invention, CH ₃ NH ₃ PbI ₃ grown from 0.038 M and 0.063 M CH ₃ NH ₃ I, respectively Sectional SEM image of the perovskite solar cell employed.
Figures 6a and 6b, according to an embodiment of the present application, each of 0.038 M CH ₃ NH ₃ I solution and 0.063 M CH ₃ NH _3, and a surface SEM image of the loading time on the I solution, Figure 6c, one of the present In the embodiment, a schematic view of a perovskite solar cell and corresponding surface and cross-sectional SEM images are shown.
(A) and (b) of Figure 7, depending on according to an embodiment of the present application, each of CH ₃ NH ₃ I concentration and the glass / FTO / dense TiO _2/100 nm- thick mesoporous substrate having a TiO ₂ structure FIG. 7C is a graph showing the transmittance and reflectance for perovskite which is dependent on the concentration of CH ₃ NH ₃ I in one embodiment of the present invention. FIG. Absorption coefficient graph.
Figure 8 shows that, in one embodiment of the invention, CH ₃ NH ₃ PbI ₃ grown in 0.032 M CH ₃ NH ₃ I Voltage curves measured under AM 1.5G illumination with a power of 99.43 mA / cm ² against the perovskite solar cell being employed, and the degree of insertion is the IPCE spectrum.
Figures 9 (a) to 9 (f) illustrate the IV curves of (a, b) 0.038 M, (c, d) 0.050 M and (e, And the blue line is the IPCE spectrum represented by the integrated J _SC .
10 is a graph of current density-voltage curves of a perovskite solar cell in which CH ₃ NH ₃ PbI ₃ crystals grown from 0.044 M and 0.057 M CH ₃ NH ₃ I are solved, in one embodiment of the present invention.
11 is a graph showing the relationship between the short circuit current density (J _SC ), open-circuit voltage (V _OC ), filling factor (FF) and photoelectric conversion efficiency (PCE) dependence of CH ₃ NH ₃ I concentration to be.
Figures 12 (a) and 12 (b) are surface SEM images of perovskite grown for loading times of 20 and 60 seconds, respectively, in one embodiment of the invention, and Figure 12 (c) Voltage curve of a perovskite solar cell in which CH ₃ NH ₃ PbI ₃ grown at 0.038 M CH ₃ NH ₃ I for 20 seconds and 60 seconds of loading time is solid.
13 (a) is a graph of current density-voltage curve measured under conditions of an incoming solar power of 99.54 mW / cm ² and AM 1.5G in one embodiment of the present application, and Fig. 13 (b) In one embodiment, CH ₃ NH ₃ PbI ₃ formed from 0.038 M CH ₃ NH ₃ I And IPCE spectra and integrated photocurrent density (J _SC ) graphs for maximum performance perovskite solar cells.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It should be understood, however, that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, the same reference numbers are used throughout the specification to refer to the same or like parts.

Throughout this specification, when a part is referred to as being "connected" to another part, it is not limited to a case where it is "directly connected," but also includes the case where it is "electrically connected" do.

Throughout this specification, when a member is " on " another member, it includes not only when the member is in contact with the other member, but also when there is another member between the two members.

Throughout this specification, when an element is referred to as " including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise. The terms " about ", " substantially ", etc. used to the extent that they are used throughout the specification are used to refer to the manufacturing and material tolerances inherent in the meanings mentioned, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure. The word " step (or step) " or " step " used to the extent that it is used throughout the specification does not mean " step for.

Throughout this specification, the term " combination (s) thereof " included in the expression of the machine form means a mixture or combination of one or more elements selected from the group consisting of the constituents described in the expression of the form of a marker, Quot; means at least one selected from the group consisting of the above-mentioned elements.

Throughout this specification, the description of "A and / or B" means "A or B, or A and B".

Throughout this specification, an "alkyl group" is typically an alkyl group having from 1 to 20 carbon atoms, from 1 to 10 carbon atoms, from 1 to 8 carbon atoms, from 1 to 5 carbon atoms, or from 1 to 3 carbon atoms, Represents a linear or branched alkyl group. When the alkyl group is substituted with an alkyl group, it is also used interchangeably as a " branched alkyl group ". Examples of the substituent which may be substituted on the alkyl group include halo (for example, F, Cl, Br, I), haloalkyl (for example, CC1 ₃ or CF ₃ ), alkoxy, alkylthio, -C (O) -OH), alkyloxycarbonyl (-C (O) -OR), alkylcarbonyloxy (-OC (O) -R), amino (-NH _2), carbamoyl (-NHC (O) OR- or -OC (O) NHR-), urea (-NH-C (O) -NHR-) and thiol (-SH). . In addition, the alkyl group having 2 or more carbon atoms in the alkyl group described above may include, but not limited to, at least one carbon to carbon double bond or at least one carbon to carbon triple bond. For example, methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, , Eicosanyl, or any of the possible isomers thereof, but is not limited thereto.

Throughout this specification, the term " halogen " or " halo " means that the halogen atom belonging to group 17 of the periodic table is included in the compound as a form of a functional group, and may be, for example, chlorine, bromine, fluorine or iodine , But may not be limited thereto.

Hereinafter, embodiments of the present invention are described in detail, but the present invention is not limited thereto.

According to a first aspect of the present invention, there is provided a method of manufacturing a light emitting device, comprising: forming a recombination preventing layer on a first electrode including a conductive transparent substrate; The recombination layer MX ₂ spin (where, M represents Pb, Sn, Ge, and include those selected from the group consisting of the combinations thereof, and, X is a halogen Im) coating, and the spin-coated MX ₂ Wherein R is a substituted or unsubstituted alkyl group, and when the R is substituted, the substituent is an amino group, a hydroxyl group, a cyano group, a halogen group, a nitro group, or a methoxy group , And X is a halogen) to form a photoactive layer comprising cubic perovskite; Forming a hole transporting layer on the photoactive layer; And forming a second electrode in the hole transporting layer. The present invention also provides a method of manufacturing a perovskite solar cell,

In one embodiment of the present invention, the conductive transparent substrate comprises at least one of indium tin oxide (ITO), fluorine tin oxide (FTO), ZnO-Ga ₂ O ₃ , ZnO-Al ₂ O ₃ , tin oxide, But are not limited to, glass substrates or plastic substrates containing materials selected from the group consisting of combinations of these. The conductive transparent substrate is not particularly limited as long as it is a conductive and transparent material. For example, the plastic substrate may be selected from the group consisting of polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polypropylene, polyimide, triacetylcellulose, and combinations thereof. .

In one embodiment of the invention, the _two -step spin-coating is performed by spin-coating the MX ₂ first with the anti-recombination layer followed by spin-coating the precursor RX for the production of perovskite, But the present invention is not limited thereto.

In one embodiment of the present invention, the step of forming the photoactive layer may further include waiting after loading the perovskite-forming precursor RX on the MX ₂ -coated anti-recombination layer, .

In one embodiment of the invention, the waiting time may be less than about 30 seconds, but may not be limited thereto. For example, the latency may be less than or equal to about 30 seconds, less than or equal to about 25 seconds, less than or equal to about 20 seconds, less than or equal to about 15 seconds, less than or equal to about 10 seconds, less than or equal to about 5 seconds, . For example, the crystal size of the cubic perovskite may be grown in proportion to the waiting time, but the present invention is not limited thereto.

In one embodiment herein, the concentration of the perovskite-forming precursor RX may be controlled within a range of about 0.03 M to about 0.07 M, but may not be limited thereto. For example, the concentration of the perovskite-forming precursor RX may range from about 0.03 M to about 0.07 M, from about 0.03 M to about 0.063 M, from about 0.03 M to about 0.057 M, from about 0.03 M to about 0.05 M, from about 0.03 M From about 0.044 M to about 0.07 M, from about 0.05 M to about 0.07 M, from about 0.057 M to about 0.07 M, or from about 0.063 M to about 0.063 M, from about 0.044 M to about 0.044 M, from about 0.03 M to about 0.038 M, from about 0.38 M to about 0.07 M, 0.0 > M, < / RTI >

In one embodiment of the present invention, the crystal size of the cubic perovskite may be controlled in the range of about 90 nm to about 720 nm by controlling the concentration of the perovskite-forming precursor RX, . For example, the crystal size of the cubic perovskite may be from about 90 nm to about 720 nm, from about 100 nm to about 720 nm, from about 200 nm to about 720 nm, from about 300 nm to about 720 nm, from about 400 nm From about 500 nm to about 720 nm, from about 600 nm to about 720 nm, from about 700 nm to about 720 nm, from about 90 nm to about 700 nm, from about 90 nm to about 600 nm, from about 90 nm to about 700 nm But may be, but not limited to, about 500 nm, about 90 nm to about 400 nm, about 90 nm to about 300 nm, about 90 nm to about 200 nm, or about 90 nm to about 100 nm. In one embodiment of the present invention, the crystal size of the cubic perovskite may be increased as the concentration of the perovskite-forming precursor RX decreases, but the present invention is not limited thereto.

In one embodiment of the present invention, the photoactive layer may further include a semiconductor layer having a porous structure, but the present invention is not limited thereto.

In one embodiment of the present invention, the semiconductor layer may include, but is not limited to, an organic semiconductor, an inorganic semiconductor, or a mixture thereof.

In one embodiment of the invention, the semiconductor layer is a _{TiO 2, SnO 2, ZnO,} WO 3, Nb 2 O 5, TiSrO 3, and may be, including but those of the metal oxide is selected from the group consisting of the combinations , But may not be limited thereto.

In one embodiment of the present invention, the semiconductor layer may be formed by coating a paste of metal oxide semiconductor nanoparticles on the recombination preventing layer, but the present invention is not limited thereto.

In one embodiment of the present invention, the cubic perovskite may be formed on the semiconductor layer or in the pores of the semiconductor layer, but the present invention is not limited thereto.

In one embodiment of the present invention, the hole transport layer may include a single molecule hole transport material or a polymer hole transport material, but the present invention is not limited thereto. For example, spiro-MeOTAD (2,2'7,7'etetrakis (N, Np-dimethoxy-phenylamino) -9,9'-spirobifluorene] can be used as the monomolecular hole- P3HT [poly (3-hexylthiophene)] may be used as the transferring material, but it may not be limited thereto. In addition, for example, the hole transport layer may be doped with a dopant selected from the group consisting of a Li-based dopant, a Co-based dopant, and combinations thereof, but is not limited thereto. For example, spiro-MeOTAD, 4-tert-butyl pyridine (tBP), and lithium bis (trifluoromethanesulfonyl) imide as the hole- imide, Li-TFSI] may be used, but the present invention is not limited thereto.

In one embodiment of the present invention, the second electrode is selected from the group consisting of Pt, Au, Ni, Cu, Ag, In, Ru, Pd, Rh, Ir, Os, C, conductive polymers, , But may not be limited thereto. For example, by using gold (Au), which is a high-stability metal, as the second electrode, the long-term stability of the perovskite solar cell of the present invention can be improved, but the present invention is not limited thereto.

According to a second aspect of the present invention, there is provided a perovskite solar cell manufactured according to the first aspect of the present invention, comprising: a first electrode including a conductive transparent substrate; An anti-recombination layer formed on the first electrode; A photoactive layer including a cubic perovskite represented by the following Chemical Formula 1 formed in the recombination preventing layer; A hole transport layer formed on the photoactive layer; And a second electrode formed on the hole transport layer, wherein the perovskite solar cell comprises:

[Chemical Formula 1]

RMX ₃

Wherein R is a substituted or unsubstituted alkyl group, and when R is substituted, the substituent is an amino group, a hydroxyl group, a cyano group, a halogen group, a nitro group, or a methoxy group, M is Pb, Sn , Ge, and combinations thereof, wherein X is a halogen.

Although a detailed description of the parts overlapping with the first aspect of the present application is omitted, the description of the first aspect of the present application may be applied to the second aspect of the present invention.

In one embodiment of the present invention, the size of the cubic perovskite crystal represented by Formula 1 may be about 90 nm to about 720 nm, but the present invention is not limited thereto.

In one embodiment of the invention, the cubic perovskite teuneun represented as the above general formula (1) may be, including the CH _3N H _3P bI _3, but may not be limited thereto.

In one embodiment of the present invention, the photoactive layer may further include a semiconductor layer having a porous structure, but the present invention is not limited thereto.

In one embodiment of the present invention, the semiconductor layer may include, but is not limited to, an organic semiconductor, an inorganic semiconductor, or a mixture thereof.

In one embodiment of the invention, the semiconductor layer is a _{TiO 2, SnO 2, ZnO,} WO 3, Nb 2 O 5, TiSrO 3, and may be, including but those of the metal oxide is selected from the group consisting of the combinations , But may not be limited thereto.

In one embodiment of the present invention, the cubic perovskite may be formed on the semiconductor layer or in the pores of the semiconductor layer, but the present invention is not limited thereto.

In one embodiment herein, the perovskite solar cell has an average PCE of greater than about 16% and a small standard deviation of less than about 0.4. Further, it is possible to manufacture a solar cell having a PCE of up to 17% by controlling the crystal size of the cubic perovskite. The cubic perovskite is formed by a two-step spin-coating process, and the crystal size of the cubic perovskite can be controlled by the concentration of the precursor for producing perovskite.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the following Examples are given for the purpose of helping understanding of the present invention, but the present invention is not limited to the following Examples.

[ Example ]

< CH ₃ NH ₃ I Synthesis of &gt;

Methylamine (27.86 mL, 40% in methanol, TCI) and hydroiodic acid (30 mL, 57 parts by weight in water, Aldrich) were mixed at 0 占 and stirred for 2 hours. The precipitate was recovered by evaporation at 50 &lt; 0 &gt; C for 1 hour. The product was washed three times with diethyl ether and finally dried at 60 DEG C in a vacuum oven for 24 hours.

< TiO ₂ Preparation of paste &gt;

Diameter of about 40 nm Anatase TiO ₂ The nanoparticles were synthesized by a two-step hydrothermal method. Seed particles of about 20 nm in diameter, synthesized by acetic acid, were catalysed by hydrolysis of titanium isopropoxide (97%, Aldrich) and autoclaved at 230 ° C for 12 hours . The seed particles were washed with ethanol and collected by centrifugation. The hydrothermal treatment was carried out again with the seed particles to increase the size. TiO ₂ The paste contains TiO ₂ (96%), lauric acid (LA) (96%), and polyvinylpyrrolidone (99.5%, Aldirich) Ti: ₂ : TP: EC: LA = 1.25: 6: 0.6: 0.1. The paste was further processed using a three-roll-mill for 40 minutes.

&Lt; Production of solar cell &

FTO glass (Pilkington, TEC-8, 8? / Sq) was washed with an ultrasonic bath containing ethanol for 20 minutes and treated with UVO cleaner for 20 minutes. TiO₂ The blocking layer (BL) was treated with 0.15 M titanium diisopropoxide bis (acetylacetonate) (75 parts by weight in isopropanol, Aldrich) in 1-butanol (99.8%, Aldrich) solution at 2,000 rpm for 20 seconds with FTO Coated on a substrate and heat-treated at 125 캜 for 5 minutes. After cooling to room temperature, the TiO₂ The paste was spin-coated on the BL layer at 2,000 rpm for 10 seconds and the initial paste was diluted in ethanol (0.1 g / mL). After drying at 100 DEG C for 5 minutes, the film was annealed at 550 DEG C for 30 minutes, which led to a thickness of about 100 nm. Mesoporous TiO₂ The films were dried at &lt; RTI ID = 0.0 &gt; 90 C &lt;₄(&Gt; 98%, Aldrich). After washing with deionized water and drying, the film was heated at 500 占 폚 for 30 minutes. CH₃NH₃PbI₃Was formed using a two-step spin-coating process. 1 M PbI₂ The solution was stirred at 70 &lt; 0 &gt; C with 1 mL N, N-dimethylformamide (N, N-dimethylformamide, DMF) (99.8%, Sigma-Aldrich)₂(99%, Aldrich). 20 μL PbI₂ The solution was mesoporous TiO₂Coated on the film at 3,000 rpm for 5 seconds and 6,000 rpm for 5 seconds (no loading time). After the spin-coating, the film was dried at 40 DEG C for 3 minutes and then at 100 DEG C for 5 minutes. After cooling to room temperature, 200 μL 0.038 M (6 mg / mL), 0.044 M (7 mg / mL), 0.050 M (8 mg / mL), 0.057 M M (10 mg / mL) in CH₃NH₃I solution was loaded for 20 seconds (loading time) with PbI₂-Coated substrate, spun-coated at 4,000 rpm for 20 seconds, and dried at 100 &lt; 0 &gt; C for 5 minutes. 20 μL 2,2 ', 7,7'-tetrakis (N, N-di- p -methoxyphenylamine) -9,9-spirobifluorene [2,2', 7,7'-tetrakis (N, N-di-p-methoxyphenylamine) -9,9-spirobifluorene, spiro-MeOTAD]₃NH₃PbI₃ Coated on the perovskite layer at 4,000 rpm for 30 seconds. The spiro-MeOTAD solution was prepared by dissolving 72.3 mg spiro-MeOTAD in 1 mL of chlorobenzene. To this was added 28.8 μL of 4-tert-butyl pyridine and 17.5 μL of lithium bis (trifluoromethanesulfonyl) imide, Li-TFSI] solution [1 mL of acetonitrile (Sigma-Aldrich, 99.8%). Finally, 80 nm of gold was thermally evaporated onto the spiro-MeOTAD coated film.

< device  Characteristic Analysis>

Photocurrent and voltage were measured from a solar simulator equipped with a 450 W Xenon Lamp (Newport 6279 NS) and a Keithley 2400 source meter. The optical density was calibrated using a NREL-tuned Si solar cell with a KG-2 filter close to a single photonic density (100 mW / cm ² ). During the measurement of current and voltage, the cell was covered with a black mask holding an aperture (the aperture area is close to the actual device area). The incident photon-to-electron conversion efficiency (IPCE) spectrum was recorded as a function of wavelength in AC mode under a constant white light bias of about 10 mW / cm ² supplied by an array of white light emitting diodes . The excitation beam from a 300-W Xenon lamp (ILC Technology) was focused through a Gemini-180 dual monochromator (JobinYvon Ltd) and shrunk at about 2 Hz. The signal was recorded using Model SR830 DSP Lock-In Amplifier (Stanford Research Systems). All measurements were performed using a non-reflective metal aperture of 0.159 cm &lt; ² &gt; to define the actual area of the device and avoid light scattering through the sides. Field-emission scanning electron microscopy (FE-SEM, Jeol JSM 6700F) was used to investigate surface and cross-sectional shapes of perovskite solar cells.

A two-step spin-coating process is shown in Fig. Mesoporous TiO ₂ (diameter about 40 nm) after the film is deposited on a thin, dense TiO ₂ barrier layer, N, N - dimethylformamide, 1 M of PbI ₂ of (N, N -dimethylformamide, DMF) 20 μL of the solution was spin-coated. As the next step, 200 μL (8 μL / cm ² ) of CH ₃ NH ₃ I solution was added to dried PbI ₂ Spin-coated on the film, and finally dried at 100 ° C to form CH ₃ NH ₃ PbI ₃ (hereinafter also referred to as 'MAPbI ₃ '). Spins of the CH ₃ NH ₃ I solution - that is, while the NH ₃ CH ₃ I 20 seconds of loading (loading) the time required for the coating before coating, PbI ₂ No loading time was required for the coating. The concentration of the CH ₃ NH ₃ I solution varied from 0.038 M (CH ₃ NH ₃ I 6 mg in 1 mL 2-propanol) to 0.063 M (10 mg / L), and the 0.063 M was used in previous reports [Burschka, J., Pellet, N., Moon, S.-J., Humphry-Baker, R., Gao, P., Nazeeruddin, MK, Gratzel, M. Sequential deposition as a route to high- sensitized solar cells. Nature 499, 316-319 (2013)]. The two-step spin-coating method of the present invention was expected to provide a more accurate method compared to the two-step immersion method because of the quantitatively managed procedure.

Herein are 2-step spin-coating process is MAPbI ₃ Leading to the formation of a cuboid, the size and the MAPBI ₃ It was also found that the shape of the cuboid was also strongly influenced by the concentration of CH ₃ NH ₃ I. As was confirmed in the SEM images of FIGS. 2 (a) to 2 (e), MAPBI ₃ The size of the cuboid is increased with the decrease of the concentration of CH ₃ NH ₃ I. The average cubic size was measured from 0.038 M to about 720 nm, from 0.044 M to about 360 nm, from 0.050 M to about 190 nm, from 0.057 M to about 130 nm, and from 0.063 M to about 90 nm. In the SEM cross section, the thickness of the increased cubic was from about 300 nm to about 400 nm, which is much slower than the a-axis and b-axis directions of the lowest concentration of 0.038 M along with the c-axis increase. As shown in FIG. 2 (f), the size distribution is wide (narrow) as the concentration decrease (increase) of CH ₃ NH ₃ I. The MAPbI ₃ cubic size was plotted as a function of CH ₃ NH ₃ I concentration in Figure 2 (g), which represents the concentration of CH ₃ NH ₃ I and the exponential decay of the cubic size. In asymptotic plateau, the exponential function provides a good form for the data, and MAPbI ₃ This suggests that the crystal growth is very related to the concentration of CH ₃ NH ₃ I. We further expanded the assay at lower concentrations, such as 0.032 M (5 mg / mL). Figures 3 (a) and 3 (b) compare cubic perovskites with concentrations of 0.032 M and 0.038 M, respectively, of the CH ₃ NH ₃ I solution. At lower concentrations of 0.032 M (loading time 60 seconds), longer loading times are required. Concentrations below 0.032 M lead to larger cubic sizes with an average volume exceeding 1 μm. Therefore, the crystal size of the cubic perovskite can be attributed to the extrapolation of the exponential curve in FIG. 2 (g).

When the crystal size of the cubic perovskite is TiO ₂ Because of its size much larger than nanoparticles (about 40 nm), the perovskite can be formed from the TiO ₂ It is not a thin conformal layer covering nanoparticles. As shown in FIGS. 4 (a) and 4 (b), the TiO ₂ The pores were filled with PbI _{2 and} the capping layer of PbI ₂ was also formed during the first coating step. During the second step of the coating process, as confirmed by XRD (data not shown), all PbI ₂ was converted to perovskite. Therefore, the perovskite has a TiO ₂ TiO ₂ as well as in pores Lt; / RTI &gt; layer. TiO ₂ Due to the pore size of the film, the growth of perovskite is limited to pores, while the larger crystal growth is due to TiO ₂ It is also possible on the top of the film. 5 (a) and 5 (b) show SEM cross sections for a full cell showing that the crystal size of the cubic perovskite influences the roughness of the spiro-MeOTAD and Au layers . The spiro-MeOTAD and the Au layer are made rougher due to contact with the cubic perovskite having a large crystal size. Although the layer structure was expected to affect the photoelectric conversion efficiency, it was found that the perovskite form ultimately plays a more important role in a given cell structure.

Herein PbI ₂ Infiltration were investigated by surface morphology changes on the scaffold (scaffold infiltrated) as a function of the load time is CH ₃ NH ₃ solution I, CH ₃ NH ₃ MAPbI ₃ I in a concentration and grain growth behavior Dependence of the cubic size was further investigated. To track the crystal growth, SEM images were monitored at different loading times of 1 second, 5 seconds, 10 seconds, and 20 seconds. Samples of SEM images for different loading times in Figs. 6A-6C were prepared as follows. For crystal growth studies, 100 μL of a CH ₃ NH ₃ I solution was added to a PbI ₂ -coated TiO ₂ After loading into the scaffold, atmospheric steps of 1 second, 5 seconds, 10 seconds, and 20 seconds (20 seconds experimental conditions) were followed. In this step, the sample was rotated at 4,000 rpm for 20 seconds and finally heated at 100 DEG C for 5 minutes. On the other hand the waiting time and crystal growth is 0.038 M CH ₃ NH ₃ I solution to a clear, crystal growth did not occur in the time even in a high concentration of 0.063 M. At 0.038 M, size growth is possible at low concentrations of CH ₃ NH ₃ I because seed crystals are sparsely dispersed (FIG. 6A). This also indicates local nucleation. In contrast to low concentrations, additional crystal growth was inhibited at high concentrations, since nucleation and growth were already terminated at an initial stage of one second, as shown in Figure 6b. The change from light brown to dark black at 0.038 M supports the notion that there is a significant difference in nuclear density in the 0.063 M case where no change is observed. Absorption near the bandgap was found as an increase in the cubic size (Fig. 7 (a) - (c)), as confirmed by the permeability and the absorption coefficient evaluated from the reflectance measurements using the integrating sphere .

As expected, V _OC And J _SC Respectively, to 0.923 V and 17 mA / cm &lt; ² &gt; respectively (Fig. 8) and the intermediate product cubic size was optimized to obtain high photovoltaic performance due to excellent light harvesting and charge carrier transport.

V _OC of the highest 1.106 V was observed in the 0.050 M CH ₃ NH ₃ I solutions. This was expected as an increase in series resistance, leading to a lower FF. The series resistance (R _s ) was estimated from the JV curve measured using the following diode equation (1). The ideal diode behavior (n = 1) is assumed and I _L , I ₀ , q, k, T and V are the photo-current, charge, inverse polarization dark saturation current, Temperature, and bias potential.

R _s was measured as 4.77 Ω cm ² , 4.85 Ωcm ² , and 8.51 Ωcm ² independently at 0.038 M, 0.050 M, and 0.063 M CH ₃ NH ₃ I, respectively. R _s increased substantially as the CH ₃ NH ₃ I concentration increased (the cubic size decreased) and correlated with the observed decrease in fill factor. The change in series resistance is considered to be related to the perovskite structure. It has been reported that in the heterostructure, the solar cell grain boundaries affect the parameters of the photovoltaic cell and the series resistance can increase through the grain boundaries. Low CH ₃ NH ₃ formed in the large I concentration-size page lobe of high fill factor observed in the sky agent became due to the lower grain boundaries cause a low series resistance.

As shown in Figs. 9 (a) to 9 (f), the integrated J _SC The values were obtained from _JSC The results were in good agreement with the figures. This indicates that the spectral mismatch between the simulator and the AM 1.5 standard solar radiation is negligible. The high average PCE of 16.4% was the main cause of high J _SC for 0.038 M CH ₃ NH ₃ I, whereas the high PCE of 16.3% for 0.050 M CH ₃ NH ₃ I is mainly due to the larger V _OC . Photovoltaic performance was also studied at intermediate product concentrations of 0.044 M and 0.057 M, and the photovoltaic parameters of the device were very consistent with the overall propensity (FIGS. 10 and 11). The loading time varied from 20 seconds to 60 seconds at a given concentration of 0.038 M, because the loading time of CH ₃ NH ₃ I could affect the crystal size of the cubic perovskite and its photovoltaic performance. Slight changes in cubic size and photovoltaic performance were observed as in Figures 12 (a) - (c), which indicated that crystal growth was complete at 20 seconds and loading lasted for 60 seconds did not reduce photovoltaic performance .

Highest PCE of 17.01% of 0.038 M CH ₃ was obtained by using the NH ₃ I, the J _SC, 1.056 V of V _OC, and fill factor of 0.741 of 21.64 mA / cm ² was obtained [in Fig. 13 (a) And (b). J _SC integrated from IPCE 21 mA / cm ² is in good agreement with the measured values. In a preferred embodiment of the invention, a significantly higher PCE of 17% is exhibited at the highest efficiency for MAPbI ₃ -based perovskite solar cells.

In conclusion, by using a two-step spin-coating process, we have developed a reproducible method for producing the highest efficiency MAPbI ₃ -based perovskite solar cells reported so far. The method yields a standard deviation of less than 0.4 and an average PCE of 16.4%. MAPBI ₃ optimized in the capping layer The cubic size was the key to obtaining high light harvesting and charge carrier transport. Herein was very strongly dependent on the concentration of CH ₃ NH ₃ I cubic size, CH ₃ NH ₃ I PbI ₂ To a solution We found that the exposure time was earlier than the spin-coating. Due to the difference in crystal size of MAPbI ₃ , the photovoltaic parameters also strongly depend on the CH ₃ NH ₃ I concentration. From the scaled growth of MAPbI ₃ , a cubic grown from a two-step spin-coating with a CH ₃ NH ₃ I concentration of greater than 0.038 M and less than 0.050 M resulted in a PCE yield of 17%.

The foregoing description of the disclosure is exemplary, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents are included in the scope of the present invention .

Claims (11)

Forming a recombination preventing layer on a first electrode including a conductive transparent substrate;
The recombination layer MX ₂ spin (where, M represents Pb, Sn, Ge, and include those selected from the group consisting of the combinations thereof, and, X is a halogen Im) coating, and the spin-coated MX ₂ Wherein R is a substituted or unsubstituted alkyl group, and when the R is substituted, the substituent is an amino group, a hydroxyl group, a cyano group, a halogen group, a nitro group, or a methoxy group , And X is a halogen) to form a photoactive layer comprising cubic perovskite;
Forming a hole transporting layer on the photoactive layer; And
Forming a second electrode on the hole transport layer
Wherein the perovskite photovoltaic cell is a photovoltaic cell.
The method according to claim 1,
Wherein the step of forming the photoactive layer further includes waiting the loading of the perovskite precursor to the MX ₂ -coated anti-recombination layer, followed by waiting.
3. The method of claim 2,
Wherein the waiting time is 30 seconds or less.
The method according to claim 1,
Wherein the concentration of the perovskite-forming precursor is controlled in the range of 0.03 M to 0.07 M.
The method of claim 3,
Wherein the crystal size of the cubic perovskite is controlled in the range of 90 nm to 720 nm by controlling the concentration of the precursor for producing the perovskite.
The method according to claim 1,
Wherein the photoactive layer further comprises a semiconductor layer having a porous structure.
The method according to claim 6,
Wherein the semiconductor layer is formed by coating a paste of metal oxide semiconductor nanoparticles on the recombination preventing layer.
8. A perovskite solar cell produced by the method according to any one of claims 1 to 7,
A first electrode comprising a conductive transparent material;
An anti-recombination layer formed on the first electrode;
A photoactive layer including a cubic perovskite represented by the following Chemical Formula 1 formed in the recombination preventing layer;
A hole transport layer formed on the photoactive layer; And
And a second electrode
A perovskite solar cell comprising:
[Chemical Formula 1]
RMX ₃
In Formula 1,
R is a substituted or unsubstituted alkyl group, and when R is substituted, the substituent is an amino group, a hydroxyl group, a cyano group, a halogen group, a nitro group, or a methoxy group,
M is selected from the group consisting of Pb, Sn, Ge, and combinations thereof,
X is a halogen.
9. The method of claim 8,
Wherein the size of the cubic perovskite crystal represented by Formula 1 is 90 nm to 720 nm.
9. The method of claim 8,
Wherein the cubic perovskite represented by Formula 1 comprises CH ₃ NH ₃ PbI ₃ .
9. The method of claim 8,
Wherein the photoactive layer further comprises a semiconductor layer having a porous structure.

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