KR102106643B1 - Method for the fabrication of perovskite solar cell and perovskite solar cell using the same - Google Patents

Abstract

The present invention relates to a manufacturing method of a perovskite solar cell and a perovskite solar cell using the same. The manufacturing method of the perovskite solar cell according to the embodiments of the present invention includes the steps of: forming a hole blocking layer including a TiO_2 thin film on a substrate; forming an electron transport layer including a mesoporous TiO_2 thin film on the hole blocking layer; performing a post-treatment process by immersing an intermediate structure, wherein the substrate, the hole blocking layer, and the electron transport layer are sequentially formed into a TiCl_4 aqueous solution; forming a light absorbing layer on the electron transport layer post-treated with the TiCl_4 aqueous solution; and forming a hole transport layer on the light absorbing layer. Therefore, the efficiency of the perovskite solar cell is improved.

Description

Manufacturing method of perovskite solar cell and perovskite solar cell using the same {METHOD FOR THE FABRICATION OF PEROVSKITE SOLAR CELL AND PEROVSKITE SOLAR CELL USING THE SAME}

The present invention relates to a method of manufacturing a perovskite solar cell and a perovskite solar cell using the same, and more specifically, to form an electron transport layer having a mesoporous structure, followed by titanium tetrachloride (TiCl ₄ as a post-treatment process) ) To improve the efficiency of the perovskite solar cell by going through a surface treatment process with an aqueous solution, the present invention relates to a method of manufacturing a perovskite solar cell and a perovskite solar cell using the same.

A solar cell converts solar energy into electrical energy, and absorbs solar energy to generate electric energy using photovoltaic effects that generate electrons and electrons.

Various types of such solar cells have been proposed, and among them, solar cells having a perovskite material, which refers to a material having the same crystal structure as calcium titanium oxide (CaTiO ₃ ), are in the spotlight. The perovskite solar cell may use an organometallic halogen compound (CH ₃ NH ₃ PbX ₃ [X is Cl, Br, I]).

The perovskite solar cell is a 3rd generation solar cell that combines silicon wafer-based technology and thin film technology, and has high absorption coefficient, variable band gap, and fast-growing characteristics compared to other solar cells.

The perovskite solar cell is superior to the silicon solar cell in terms of price, rigidity, weight, and efficiency, but there are still problems to be solved for commercialization. That is, there are still problems to be solved in consideration of moisture, heat, and long-term stability resistance to sunlight, morphology, grain size, defects of grain boundaries, and solar cells.

Recently, a perovskite solar cell uses TiO ₂ as an electron transfer layer (ETL). However, TiO ₂ is good for transporting electrons, but exhibits very low electron mobility (10 ^-3 cm 2 / Vs or less), and forms deep traps by UV light, causing charge accumulation, severe current-voltage hysteresis and recombination. You can.

Therefore, the perovskite solar cell is in need of research and development to improve charge separation and electron transport between the electron transport layer (TiO ₂ ) and the perovskite interface.

Republic of Korea Registered Patent Publication No. 10-1654310 (Registration on August 30, 2016) Republic of Korea Registered Patent Publication No. 10-1828943 (Registration on Feb. 7, 2018)

An object of the present invention is to improve the perovskite solar cell efficiency by forming an electron transport layer having a mesoporous structure, followed by a surface treatment process with an aqueous solution of titanium tetrachloride (TiCl ₄ ) as a post-treatment process. It is to provide a method of manufacturing a lobsky solar cell and a perovskite solar cell using the same.

A method of manufacturing a perovskite solar cell according to an embodiment of the present invention includes forming a hole blocking layer containing a TiO ₂ thin film on a substrate; Forming an electron transport layer including a mesoporous TiO ₂ thin film on the hole blocking layer; Performing a post-treatment process by immersing the substrate, the hole blocking layer and the electron transport layer in a TiCl ₄ aqueous solution in an ordered intermediate structure; Forming a light absorbing layer on the electron transport layer post-treated with the TiCl ₄ aqueous solution; And forming a hole transport layer on the light absorbing layer, wherein the hole blocking layer is formed through spin-coating a first TiO ₂ solution on the substrate and then annealing. The first TiO ₂ solution is prepared by diluting 0.55 µl titanium diisopropoxide bis (acetylacetonate) in a 1 ml butanol solution, and the electron transport layer is formed on the hole blocking layer. The second TiO ₂ solution is spin coated and then formed through annealing. The second TiO ₂ solution is prepared by diluting 0.4 g TiO ₂ paste in 4.6 g absolute ethanol (99.5%), and the TiO ₂ paste is sol- Prepared using a gel reaction method, 6 g TiO ₂ anatase powder and 1 ml acetic acid were subjected to ball milling at 200 rpm for 24 hours, followed by 60% amplitude. 2 seconds on, 2 seconds off for 30 minutes 4 The first ultrasonic treatment proceeds sequentially, and 25.8 ml alpha-terpineol is mixed to perform the second ultrasonic treatment under the same conditions, 7.5 g ethyl cellulose and 121 ml ethanol ( ethanol) and the third sonication under the same conditions. After evaporating ethanol at 200 rpm for 30 minutes at 100 ° C., it may be produced by performing a three-roller mill for 30 minutes.

The TiCl ₄ aqueous solution may be formed by mixing titanium (IV) colloid (TiCl ₄ , 98%) in water.

The post-treatment process includes: immersing the intermediate structure in the TiCl ₄ aqueous solution at 70 ° C. for 30 minutes and washing with deionized water; And heat-treating the washed intermediate structure at 450 ° C for 40 minutes, and then cooling at room temperature.

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The light absorbing layer may be to form an organometallic halogen compound through a spin coating process.

The forming of the light absorbing layer may include: forming a first layer by spin-coating a PbI ₂ solution on the electron transport layer post-treated with the TiCl ₄ aqueous solution; And forming a second layer by spin-coating a mixed solution of methylammonium iodide (MAI) on the first layer.

The PbI ₂ solution may be formed by mixing 647 mg PbI ₂ (99%) in 100 μl dimethylsulfoxide and 1 mL N, N-dimethylformamide.

The methyl ammonium aodide (MAI) mixed solution may be formed by mixing 12 mg CH ₃ NH ₃ I in 1 ml 2-propanol.

The hole transport layer may be formed by coating a Spiro-MeOTA solution.

As for the Spiro-MeOTA solution, 72.3 mg Spiro-MeOTA contains 1 mL chlorobenzene, 28.8 μL 4-tert-butyl pyridine, and 17.5 μL lithium bis (trifluoromethanesulfonyl). ) Imide [lithium bis (tri fluoro methane sulphonyl) imid] (Li-TFSI) may be prepared by mixing in a solution.

The Li-TFSI solution may be formed by mixing 520 mg Li-TFSI in 1 mL acetonitrile (acetonitrile, 99.8%).

Between the substrate and the hole blocking layer, it may be to form a transparent conductive material.

After forming the hole transport layer, forming a first electrode for electrical connection with the transparent conductive material, and forming a second electrode for electrical connection with the hole transport layer; may further include a.

The present invention can improve the efficiency of the perovskite solar cell by forming an electron transport layer having a mesoporous structure, followed by surface treatment with an aqueous solution of titanium tetrachloride (TiCl ₄ ) as a post-treatment process.

In addition, the present invention can reduce the surface roughness of the TiO ₂ thin film and the perovskite thin film when the TiO ₂ surface is treated with 80 mM TiCl ₄ .

In addition, the present invention can improve the light absorption and electron mobility of the perovskite thin film.

1 is a view showing a perovskite solar cell according to an embodiment of the present invention,
2 is a view showing a method of manufacturing a perovskite solar cell according to an embodiment of the present invention,
3 is a view for explaining a manufacturing process of a TiO ₂ paste according to an embodiment of the present invention,
4a to 4b is a photograph showing an AFM image of the TiCl ₄ treated TiO ₂ surface,
Figure 5a is a view showing the current density and voltage characteristics in the solar cell according to the treatment result of the TiCl ₄ aqueous solution,
Figure 5b is a diagram showing the external photon efficiency characteristics in the solar cell according to the treatment result of TiCl ₄ aqueous solution,
6 is a view showing the results of optical performance factors,
Figure 7a is a diagram showing the short-circuit current density in Figure 6,
Figure 7b is a view showing the open voltage in Figure 6,
Figure 7c is a view showing the solar cell charge rate in Figure 6,
Figure 7d is a view showing the energy conversion efficiency in Figure 6,
8 is a view showing an XRD pattern,
9a is a photograph showing an SEM image of untreated TiO ₂ ,
Figure 9b is a photo showing the SEM image of the post-treated TiO ₂ ,
10 is a view showing the UV-VIS spectrum,
11A is a photograph showing an AFM image of a perovskite thin film grown on an untreated TiO ₂ thin film,
11B is a photograph showing an AFM image of a perovskite thin film grown on a post-treated TiO ₂ thin film.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in the following description and accompanying drawings, detailed descriptions of well-known functions or configurations that may obscure the subject matter of the present invention are omitted. In addition, it should be noted that the same components throughout the drawings are denoted by the same reference numerals as much as possible.

The terms or words used in the present specification and claims described below should not be interpreted as being limited to ordinary or dictionary meanings, and the inventor appropriately defines terms as terms for explaining his or her invention in the best way. Based on the principle that it can be done, it should be interpreted as a meaning and a concept consistent with the technical idea of the present invention.

Therefore, the configuration shown in the embodiments and drawings described in this specification is only one of the most preferred embodiments of the present invention, and does not represent all of the technical spirit of the present invention, and can replace them at the time of this application. It should be understood that there may be equivalents and variations.

In the accompanying drawings, some components are exaggerated, omitted, or schematically illustrated, and the size of each component does not entirely reflect the actual size. The present invention is not limited by the relative size or spacing drawn in the accompanying drawings.

When a part of the specification "includes" a certain component, this means that other components may be further included instead of excluding other components unless specifically stated otherwise. In addition, when a part is said to be "connected" to another part, this includes not only "directly connected" but also "electrically connected" with other elements in between.

Singular expressions include plural expressions unless the context clearly indicates otherwise. The terms "include" or "have" are intended to indicate the presence of features, numbers, steps, actions, components, parts or combinations thereof described in the specification, one or more other features or numbers or steps. It should be understood that it does not preclude the existence or addition possibility of the operation, components, parts or combinations thereof.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains may easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. In addition, in order to clearly describe the present invention in the drawings, parts irrelevant to the description are omitted, and like reference numerals are assigned to similar parts throughout the specification.

The spatially relative terms “below”, “beneath”, “lower”, “above”, “upper”, etc., are as shown in the figure. It can be used to easily describe a correlation between a component and other components. The spatially relative terms should be understood as terms including different directions of components in use or operation in addition to the directions shown in the drawings. For example, when a component shown in the drawing is turned over, a component described as "below" or "beneath" of another component will be placed "above" another component. You can. Thus, the exemplary term “below” can include both the directions below and above. Components can also be oriented in different directions, and thus spatially relative terms can be interpreted according to orientation.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

1 is a view showing a perovskite solar cell according to an embodiment of the present invention.

As shown in Figure 1, the perovskite solar cell 100 according to an embodiment of the present invention, an electron transport layer (Electron Transport Layre, ETL) through a surface treatment using titanium tetrachloride (Titanium tetrachloride, TiCl ₄ ) ) Can improve the charge transport efficiency.

The perovskite solar cell 100 includes a substrate 10, a first electrode 20, a hole blocking layer (HBL) 30, an electron transport layer 40, a light absorbing layer 50, holes It includes a transport layer (Hole Transport Layre, HTL) 60, a second electrode (70).

First, the substrate 10 may be an inorganic substrate or an organic substrate. That is, the inorganic substrate may be made of, for example, glass, quartz, Al ₂ O ₃ , SiC, Si, GaAs, or InP, but is not limited thereto. In addition, the organic substrate may be, for example, spheron foil, polyimide (PI), polyethersulfone (PES), polyacrylate (PAR), polyetherimide (PEI), polyethylene or Phthalate (polyethylene naphthalate, PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyarylate, polycarbonate, PC, cellulose triacetate , CTA) and cellulose acetate propionate (CAP), but is not limited thereto. The substrate 10 is more preferably made of a transparent material through which light is transmitted, and can be used as long as it is a substrate that can be positioned on the front electrode in a conventional solar cell. When the organic substrate is introduced, the flexibility of the electrode can be increased.

In addition, a transparent conductive material may be thinly formed on the substrate 10 to improve the transmission of a conductive material, particularly light. Here, the transparent conductive material corresponds to an electrode provided on the light-receiving side of light, for example, FTO (Fluorine doped Tin Oxide), ITO (Indium doped Tin Oxide), AZO (Al-doped Zinc Oxide), IZO (Indium doped) Zinc Oxide, IZO), TCO (Transparent Conducting Oxide), CNT (Carbon Nanowire), silver nanowire, graphene, conductive polymer, or mixtures thereof. , But is not limited thereto. Methods for forming such a transparent conductive material on the substrate 10 include thermal evaporation, e-beam evaporation, RF frequency sputtering, magnetron sputtering, and vacuum deposition ( vacuum deposition) or chemical vapor deposition.

Next, the first electrode 20 corresponds to an electrode for electrical connection with a transparent conductive material. The second electrode 70 to be described later also corresponds to an electrode for electrical connection with the hole transport layer 60. Here, the first electrode 20 and the second electrode 70 are, for example, gold (Au), silver (Ag), platinum (Pt), palladium (Pd), copper (Cu), aluminum (Al), Carbon (C), cobalt sulfide (CoS), copper sulfide (CuS), nickel oxide (NiO), or a mixture thereof, but may not be limited thereto.

Next, the hole blocking layer 30 is formed on the transparent conductive material of the substrate 10. Since the hole blocking layer 30 has a deep HOMO (Highest Occupied Molecular Orbital) level (deep HOMO level), it is possible to prevent recombination by preventing the movement of holes. In addition, the hole blocking layer 30 may include a metal oxide selected from TiO ₂ , ZnO, SrTi0 ₃ , WO ₃ or a mixture thereof, and preferably includes TiO ₂ but has a compact structure. Can have

Next, the electron transport layer 40 is formed on the hole blocking layer 30. At this time, the electron transport layer 40 is located between the first electrode 20 and the light absorbing layer 50 so that electrons generated in the light absorbing layer 50 can be easily transferred to the first electrode 20 through a transparent conductive material. do.

The electron transport layer 40 has a mesoscopic structure made of a mesoporous layer. The electron transport layer 40 may be, for example, a TiO ₂ based or Al ₂ O ₃ based porous material, but is not limited thereto.

As an example, when using the TiO ₂ series, a TiO ₂ paste prepared through a sol-gel reaction method is applied. In this case, the electron transport layer 40 forms a mesoscopic structure using TiO ₂ and then undergoes a surface treatment process with an aqueous solution of titanium tetrachloride (TiCl ₄ ) as a post-treatment process. This will be described in detail with reference to FIG. 2 to be described later.

Next, the light absorbing layer 50 has a perovskite structure using an organometallic halogen compound on the electron transport layer 40. Here, the organometallic halogen compound may be CH ₃ NH ₃ PbX ₃ (X is Cl, Br, I), preferably CH ₃ NH ₃ PbI ₃ .

The light absorbing layer 50 is located between the first electrode 20 and the second electrode 70, and serves to serve as a photoelectric conversion layer that generates current by separating electrons and holes. do.

When a perovskite structure is introduced in the light absorbing layer 50, the HOMO (Highest Occupied Molecular Orbital) level of the hole transport layer 60 and the LUMO (Lowest Unoccupied Molecular Orbital) level of the electron transport layer 40 are each perovskite. It is well matched with Skyt's valence band and conduction band, and electrons are well transferred toward the electron transport layer 40 and holes are transported toward the hole transport layer 60.

Through this mechanism, electron-hole pairs can be effectively separated into electrons and holes, and the separated electrons and holes are formed by an internal electric field formed by a difference in work function between the first electrode 20 and the second electrode 70 and accumulated charge. It is collected by moving to each electrode due to the difference in concentration, and finally flows in the form of current through an external circuit.

Next, the hole transport layer 60 is formed on the light absorbing layer 50. At this time, the hole transport layer is located between the second electrode 70 and the light absorbing layer 50 so that holes generated in the light absorbing layer 50 are easily transferred to the second electrode 70.

The hole transport layer 60 is, for example, P3HT (poly [3-hexylthiophene]), MDMO-PPV (poly [2-methoxy-5- (3 ', 7'-dimethyloctyloxyl))-1,4-phenylene vinylene ), MEH-PPV (poly [2-methoxy-5- (2 ''-ethylhexyloxy) -p-phenylene vinylene]), P3OT (poly (3-octyl thiophene)), POT (poly (octyl thiophene)), P3DT (poly (3-decyl thiophene)), P3DDT (poly (3-dodecyl thiophene), PPV (poly (p-phenylene vinylene)), TFB (poly (9,9'-dioctylfluorene-co-N- (4-butylphenyl) ) diphenyl amine), Polyaniline, Spiro-MeOTAD ([2,22 ', 7,77' '-tetrkis (N, N-dipmethoxyphenylamine) -9,9,9'-spirobi fluorine]), CuSCN, CuI, PCPDTBT ( Poly [2,1,3-benzothiadiazole-4,7-diyl [4,4-bis (2-ethylhexyl-4H-cyclopenta [2,1-b: 3,4-b '] dithiophene-2,6-diyl ]], Si-PCPDTBT (poly [(4,4'-bis (2-ethylhexyl) dithieno [3,2-b: 2 ′ ', 3'-d] silole) -2,6-diyl-alt- ( 2,1,3-benzothiadiazole) -4,7-diyl]), PBDTTPD (poly ((4,8-diethylhexyloxyl) benzo ([1,2-b: 4,5-b '] dithiophene) -2,6 -diyl) -alt-((5-octylthieno [3,4-c] pyrrole-4,6-dione) -1,3-diyl)), PFDTBT (poly [2,7- (9- (2-ethylhexyl) ) -9-hexyl-fluorene) -alt-5,5 -(4 ', 7, -di-2-thienyl-2', 1 ', 3'-benzothiadiazole)]), PFO-DBT (poly [2,7-.9,9- (dioctyl-fluorene) -alt) -5,5- (4 ', 7'-di-2-.thienyl-2', 1 ', 3'-benzothiadiazole)]), PSiFDTBT (poly [(2,7-dioctylsilafluorene) -2,7-diyl -alt- (4,7-bis (2-thienyl) -2,1,3-benzothiadiazole) -5,5'-diyl]), PSBTBT (poly [(4,4'-bis (2-ethylhexyl) dithieno [3,2-b: 2 ′ ', 3'-d] silole) -2,6-diyl-alt- (2,1,3-benzothiadiazole) -4,7-diyl]), PCDTBT (Poly [[ 9- (1-octylnonyl) -9H-carbazole-2,7-diyl] -2,5-thiophenediyl-2,1,3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl]), PFB (poly (9,9'-dioctylfluorene-co-bis (N, N ''-(4, butylphenyl)) bis (N, N'-phenyl-1,4-phenylene) diamine), F8BT (poly (9,9 ' -dioctylfluorene-cobenzothiadiazole), PEDOT (poly (3,4-ethylenedioxythiophene)), PEDOT: PSS (poly (3,4-ethylenedioxythiophene) poly (styrenesulfonate)), PTAA (poly (triarylamine)), poly (4-butylphenyldiphenyl- amine) and copolymers thereof.

Hereinafter, a method of manufacturing a perovskite solar cell will be described in detail with reference to FIG. 2.

2 is a view showing a method of manufacturing a perovskite solar cell according to an embodiment of the present invention.

Referring to Figure 2, the substrate 10 is cleaned using an ultrasonicator (ultrasonicator) (S101).

Next, the hole blocking layer 30 is formed on the cleaned substrate 10 (S102). At this time, when the hole blocking layer 30 is formed of a compact TiO ₂ thin film (compact TiO ₂ ), spin-coating a TiO ₂ solution on the substrate 10 and then annealing Form through. Here, the TiO ₂ solution is prepared by diluting 0.55 μl titanium diisopropoxide bis (acetylacetonate) in a 1 ml butanol solution. Then, spin coating is performed at 3000 rpm for 30 seconds, and annealing is performed at 120 ° C. for 10 minutes in a furnace equipment.

Next, the electron transport layer 40 is formed on the hole blocking layer 30 (S103). At this time, when the electron transport layer 40 is formed of a mesoporous TiO ₂ thin film having a mesoscopic structure, the TiO ₂ solution is spin coated on the hole blocking layer 30 and then formed through annealing. Here, the TiO ₂ solution is prepared by diluting 0.4 g TiO ₂ paste in 4.6 g absolute ethanol (99.5%). Then, spin coating is performed at 3000 rpm for 30 seconds, and annealing is performed at 450 ° C. for 30 minutes in the furnace equipment.

In addition, TiO ₂ paste is prepared using a sol-gel reaction method as shown in FIG. 3. 3 is a view illustrating a manufacturing process of a TiO ₂ paste according to an embodiment of the present invention. According to the embodiment of FIG. 3, first, 6 g TiO ₂ anatase powder and 1 ml acetic acid are subjected to ball milling at 200 rpm for 24 hours (S1). Subsequently, after performing the first ultrasonic treatment that proceeds 4 times for 30 minutes for 2 seconds on and 2 seconds off at 60% amplitude (S2), 25.8 ml alpha-terpineol is mixed. Then, the second ultrasonic treatment is performed under the same conditions (S3), and 7.5 g ethyl cellulose and 121 ml ethanol are mixed to perform the third ultrasonic treatment under the same conditions (S4). Then, after evaporating ethanol at 200 rpm for 30 minutes at 100 ° C (S5), and then proceeding with a three-roller mill for 30 minutes (S6), a TiO2 paste is produced.

In particular, after the electron transport layer 40 is formed, the intermediate structure formed in the order of the substrate 10-hole blocking layer 30-electron transport layer 40 is immersed in an aqueous TiCl ₄ solution to perform a post-treatment process (S104) ). Here, the TiCl ₄ aqueous solution is formed by mixing titanium (IV) colloid (TiCl ₄ , 98%) in water. TiCl ₄ aqueous solution shows the highest treatment effect at 80 mM.

Specifically, when the post-treatment process is performed with a TiCl ₄ aqueous solution, the intermediate structure formed in the order of substrate 10-hole blocking layer 30-electron transport layer 40 is immersed in a TiCl ₄ aqueous solution at 70 ° C for 30 minutes and deionized water Wash with. Thereafter, the washed intermediate structure is heat-treated at 450 ° C for 40 minutes and then cooled at room temperature.

Next, the light absorbing layer 50 is formed on the electron transport layer 40 post-treated with a TiCl ₄ aqueous solution (S105). The light absorbing layer 50 is formed of a perovskite material in a glove box.

At this time, when the light absorbing layer 50 is formed of CH ₃ NH ₃ PbI ₃ as an organometallic halogen compound, it is prepared through a two-step spin coating process. First, the first layer of the light absorbing layer 50 is spin-coated with a PbI ₂ solution at 3000 rpm for 35 seconds on the electron transport layer 40 post-treated with a TiCl ₄ aqueous solution. Here, the PbI ₂ solution is formed by mixing 647 mg PbI ₂ (99%) in 100 µl dimethylsulfoxide and 1 ml N, N-dimethylformamide. This proceeds for 60 minutes at 70 ° C and 300 rpm. Next, the second layer of the light absorbing layer 50 is spin-coated with a mixed solution of Methylammonium Iodide (MAI) (ie, CH ₃ NH ₃ I) at 4000 rpm for 60 seconds on the first layer. Here, the MAI mixed solution is formed by mixing 12 mg CH ₃ NH ₃ I in 1 ml 2-propanol. This proceeds for 20 minutes at 300 rpm. As described above, the light absorbing layer 50 is subjected to a two-step spin coating process, dried at 150 ° C for 10 minutes, and then dried at 120 ° C for 40 minutes.

Next, the hole transport layer 60 is formed on the light absorbing layer 50 (S106). At this time, when the hole transport layer 60 forms Spiro-MeOTA, a Spiro-MeOTA solution is prepared and coated on the light absorbing layer 50. Here, the Spiro-MeOTA solution contains 72.3 mg Spiro-MeOTA containing 1 mL chlorobenzene, 28.8 μL 4-tert-butyl pyridine, and 17.5 μL lithium bis (trifluoromethanesulfonyl). ) Imide [lithium bis (tri fluoro methane sulphonyl) imid] (Li-TFSI) prepared by mixing. Then, the Li-TFSI solution is formed by mixing 520 mg Li-TFSI in 1 ml acetonitrile (acetonitrile, 99.8%).

Next, the first electrode 20 is formed on the substrate 10, and the second electrode 70 is formed on the light absorbing layer 50 (S107). At this time, the first electrode 20 and the second electrode 70 may form a metal having a thickness of 100 nm by thermal evaporation. The first electrode 20 and the second electrode 70 may be made of gold (Au).

As described above, the perovskite solar cell 100 according to the embodiment of the present invention includes a mesoporous TiO ₂ thin film, that is, an electron transport layer 40, which has been subjected to a post-treatment process with a TiCl ₄ aqueous solution.

Hereinafter, the effect on the post-treatment process of the TiCl ₄ aqueous solution will be described with reference to the drawings to be described later.

Accordingly, the experimental results of the perovskite solar cell according to the treatment process (pre-treatment, pre-treatment and post-treatment, non-treatment) of the TiCl ₄ aqueous solution will be compared and described.

In the pre-treatment process of the TiCl ₄ aqueous solution, the substrate 10 before the hole blocking layer 30 was formed was immersed in TiCl ₄ aqueous solution at 70 ° C. for 30 minutes, and then washed with deionized water, and then the substrate 10 was 40 at 450 ° C. This is the process of heat treatment for a minute.

4A to 4B are photographs showing atomic force microscopy (AFM) images of TiCl ₄ treated TiO ₂ surfaces. FIG. 4A shows the AFM image of the TiCl ₄ untreated TiO ₂ surface, FIG. 4B shows the AFM image of the TiCl ₄ pre-treated TiO ₂ surface, and FIG. 4C shows the TiCl ₄ post treatment The AFM image for the post-treated TiO ₂ surface is shown, and FIG. 4D shows the AFM image for the TiCl ₄ pre and post-treated TiO ₂ surface.

The roughness of the TiCl ₄ treated TiO ₂ surface is shown through the AFM image. RMS (Root-Mean Square) roughness is one of the parameters in the AFM image.

The TiCl ₄ post-treated TiO ₂ surface of FIG. 4C exhibits a lower RMS roughness than other TiO ₂ surfaces of FIGS. 4A, 4B, and 4. That is, of the TiO ₂ surface treatment 4c of TiCl ₄ and then RMS roughness 57.9㎚, and Figure 4a of TiCl ₄ in the untreated TiO ₂ surface RMS roughness 72.9㎚, the TiCl ₄ the TiO ₂ pre-processing the surface of Fig. 4b RMS The roughness is 64.2 nm, and the RMS roughness of the TiCl ₄ pre / post-treated TiO ₂ surface in FIG. 4D is 64.3 nm. Electron transport is easier as the RMS roughness is lower.

Figure 5a is TiCl current density and voltage characteristics of the solar cell according to the processing result of the _fourth solution is a diagram showing a (JV characteristics), Figure 5b is a TiCl ₄ aqueous solution external photon efficiency (External Quantum Efficiency in the solar cell according to the result of processing, EQE) This is a diagram showing the characteristics.

When FIG. 5a and FIG 5b, TiCl ₄ aqueous solution of solar cells (post-treated TiO ₂₎ including a treatment TiO ₂ and then to the JV characteristics than a solar cell (untreated TiO ₂₎ containing the untreated TiO ₂ and Both EQE properties show improved results.

On the other hand, factors that tell the optical performance of the solar cells (untreated TiO ₂₎ including a containing the treated TiO ₂ solar cells (post-treated TiO ₂₎ and the untreated TiO ₂ after the TiCl ₄ aqueous solution (i.e., J _SC , V _OC, FF, PCE) can be represented as shown in the table of FIG. 6. Moreover, FIG. 6 is a diagram showing the results of optical performance factors, and may be specifically shown as in FIGS. 7A to 7D.

Here, the short circuit current density (J _SC ) represents the current density in the reverse direction (negative value when light is received in a state in which the circuit is short-circuited, that is, without external resistance). In addition, the open voltage (Open Circuit Voltage, V _OC ) represents a potential difference formed at both ends of the solar cell when light is received while the circuit is open, that is, infinite impedance is applied. In addition, the solar cell charge factor (Fill factor, FF) is a value obtained by dividing the product of the current density and the voltage value at the maximum power point by the product of V _OC and J _SC . In addition, Energy Conversion Efficiency (PCE) represents the efficiency of converting solar energy incident on a solar cell into electrical energy, and is a value obtained by dividing the product of V _OC , J _SC and FF by the incident solar energy.

7A is a diagram showing the short-circuit current density in FIG. 6, FIG. 7B is a diagram showing the open voltage in FIG. 6, FIG. 7C is a diagram showing the solar cell charge rate in FIG. 6, and FIG. 7D is the diagram 6 is a diagram showing the energy conversion efficiency.

6, the solar cell (post-treated TiO ₂₎ including a treatment TiO ₂ after a high short circuit current density than the solar cells (untreated TiO ₂₎ containing the untreated TiO ₂ (J _SC) and the open Voltage (V _OC ), and as a result, energy conversion efficiency (PCE) is improved.

Short circuit current density (J _SC ) relates to electron extraction, collection and limited electron recombination. Through this, the improvement of the short-circuit current density (J _SC ) decreases the sub-band gap absorption according to the TiCl ₄ aqueous solution treatment, which not only induces trap state passivation at the interface, but also increases the electron transport of the metal oxide. it means.

8 is a view showing an XRD (X Ray Diffraction) pattern.

8, the XRT pattern represents an X-ray diffraction pattern, and the peaks of the samples can be observed.

The peak observed at the surface index 101 of the XRD pattern indicates a nanoporous structure of TiO ₂ . This is seen in untreated TiO ₂ / FTO (untreat TiO ₂ / FTO) and post-treated TiO ₂ / FTO (post treat TiO ₂ / FTO).

After the treated _{TiO 2 / FTO (post treat TiO} 2 / FTO) represents the diffraction intensity higher than the _{TiO 2 / FTO (untreat TiO 2} / FTO) untreated. This indicates that the after-treated _{TiO 2 / FTO (post treat TiO} 2 / FTO) is the electron transport enhanced compared to the untreated _{TiO 2 / FTO (untreat TiO 2} / FTO).

9A is a photograph showing an SEM image of untreated TiO ₂ , and FIG. 9B is a photograph showing an SEM image of post-treated TiO ₂ .

9A and 9B, the SEM image shows the crystal structure of the TiO2 thin film. The post-treated TiO ₂ thin film exhibits improved surface coverage compared to the untreated TiO ₂ film. This shows a more efficient result for electron movement, and is consistent with the result of the XRD pattern confirmed through FIG. 8.

10 is a view showing the UV-VIS spectrum.

10 shows light absorption results of an untreated TiO ₂ based light absorbing layer (ie, a perovskite thin film) and a post-treated TiO ₂ based light absorbing layer through a UV-VIS spectrum.

While the TiO ₂ thin film acts as an electron transport layer, the perovskite thin film acts as a light absorbing layer, which plays an important role in the overall solar cell structure.

Perovskite thin film containing TiO ₂ thin film and then processed, as shown in Figure 10 is better than the perovskite thin film containing the untreated TiO ₂ thin film in all the range between 400㎚~800㎚ The light absorption results are shown.

This means that the result of the TiCl ₄ aqueous solution treatment has an organic relationship to the performance of the light absorbing layer, and the efficiency of the solar cell including the post-treated TiO ₂ thin film is better than that of the solar cell including the untreated TiO ₂ thin film.

11A is a photograph showing an AFM image of a perovskite film grown on an untreated TiO ₂ thin film, and FIG. 11B is a photograph showing an AFM image of a perovskite film grown on a post-treated TiO ₂ thin film.

The RMS roughness of the perovskite film grown on the untreated TiO ₂ thin film of FIG. 11A is 15.054 nm, and the RMS roughness of the perovskite film grown on the post-treated TiO ₂ thin film of FIG. 11B is 14.584 nm.

That is, the RMS roughness of the perovskite thin film decreased from 15.054 nm to 14.584 nm according to the result of the TiCl ₄ aqueous solution treatment.

Looking at the AFO image, the TiCl ₄ aqueous solution treatment shows that the TiO ₂ thin film can be smoothly treated, and it can be seen that the perovskite thin film properties are related to the surface properties of the TiO ₂ thin film.

Although the above description has been described with a focus on the novel features of the present invention applied to various embodiments, a person skilled in the art does not depart from the scope of the present invention and the apparatus and method described above It will be understood that various deletions, substitutions, and changes are possible in the form and details of the. Accordingly, the scope of the invention is defined by the appended claims rather than in the above description. All modifications within the equivalent scope of the claims are covered by the scope of the present invention.

10; Substrate 20; First electrode
30; Hole blocking layer 40; Electron transport layer
50; Light absorbing layer 60; Hole transport layer
70; Second electrode

Claims (16)

Forming a hole blocking layer including a TiO ₂ thin film on a substrate;
Forming an electron transport layer including a mesoporous TiO ₂ thin film on the hole blocking layer;
Performing a post-treatment process by immersing the substrate, the hole blocking layer and the electron transport layer in a TiCl ₄ aqueous solution in an ordered intermediate structure;
Forming a light absorbing layer on the electron transport layer post-treated with the TiCl ₄ aqueous solution; And
Including; forming a hole transport layer on the light absorbing layer;
The hole blocking layer is formed by spin-coating a first TiO ₂ solution on the substrate and then annealing, but the first TiO ₂ solution is 0.55 μl titanium diisopropoxide bis ( It is prepared by diluting acetylacetonate (titanium diisopropoxide bis (acetylacetonate)) in 1 ml butanol solution.
The electron transport layer is formed by spin coating a second TiO ₂ solution on the hole blocking layer, followed by annealing, wherein the second TiO ₂ solution is diluted with 0.4 g TiO ₂ paste in 4.6 g absolute ethanol (99.5%). Manufacturing,
The TiO ₂ paste was prepared using a sol-gel reaction method, after 6 g TiO ₂ anatase powder and 1 ml acetic acid were subjected to ball milling at 200 rpm for 24 hours. , 2 seconds on, 2 seconds off at 60% amplitude (amplitude), the first ultrasonic treatment proceeds four times for 30 minutes, 25.8 ml alpha-terpineol (α-terpineol) is mixed to remove the same conditions. 2 The ultrasonic treatment is performed, and 7.5 g ethyl cellulose and 121 ml ethanol are mixed to perform the third ultrasonic treatment under the same conditions. A method of manufacturing a perovskite solar cell that is produced by evaporating ethanol at 200 rpm for 30 minutes at 100 ° C. and then proceeding through a three-roller mill for 30 minutes.
According to claim 1,
The TiCl ₄ aqueous solution,
A method of manufacturing a perovskite solar cell, which is formed by mixing titanium (IV) colloid (TiCl ₄ , 98%) in water.
According to claim 1,
The post-treatment process,
Immersing the intermediate structure in the TiCl ₄ aqueous solution at 70 ° C. for 30 minutes and washing with deionized water; And
Heat-treating the washed intermediate structure at 450 ° C for 40 minutes and then cooling at room temperature;
Method of manufacturing a perovskite solar cell comprising a.
delete delete delete According to claim 1,
The light absorbing layer,
A method of manufacturing a perovskite solar cell, wherein the organometallic halogen compound is formed through a spin coating process.
The method of claim 7,
The step of forming the light absorbing layer,
Forming a first layer by spin-coating a PbI ₂ solution on the electron transport layer post-treated with the TiCl ₄ aqueous solution; And
Forming a second layer on the first layer by spin-coating a mixed solution of methylammonium iodide (MAI);
Method of manufacturing a perovskite solar cell comprising a.
The method of claim 8,
The PbI ₂ solution,
A method of manufacturing a perovskite solar cell that is formed by mixing 647 mg PbI ₂ (99%) in 100 µl dimethylsulfoxide and 1 ml N, N-dimethylformamide.
The method of claim 8,
The methyl ammonium iodide (MAI) mixed solution,
A method of manufacturing a perovskite solar cell, which is formed by mixing 12 mg CH ₃ NH ₃ I in 1 ml 2-propanol.
According to claim 1,
The hole transport layer,
A method of manufacturing a perovskite solar cell formed by coating a Spiro-MeOTA solution.
The method of claim 11,
The Spiro-MeOTA solution,
72.3mg Spiro-MeOTA contains 1ml chlorobenzene, 28.8µl 4-tert-butyl pyridine, and 17.5µl lithium bis (trifluoromethanesulfonyl) imide [lithium bis ( tri fluoro methane sulphonyl) imid] (Li-TFSI) is a method of manufacturing a perovskite solar cell prepared by mixing in a solution.
The method of claim 12,
The Li-TFSI solution,
A method of manufacturing a perovskite solar cell in which 520 mg Li-TFSI is formed by mixing with 1 ml acetonitrile (99.8%).
According to claim 1,
Between the substrate and the hole blocking layer,
A method of manufacturing a perovskite solar cell that forms a transparent conductive material.
The method of claim 14,
After forming the hole transport layer, forming a first electrode for electrical connection with the transparent conductive material and a second electrode for electrical connection with the hole transport layer;
Method of manufacturing a perovskite solar cell further comprising a.
A perovskite solar cell manufactured by the method of manufacturing the perovskite solar cell of claim 1.

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