KR102491190B1 - Hole transporting materials for solar cells and solar cells comprising the same - Google Patents

Abstract

The present invention relates to a hole transport material for a solar cell and a solar cell including the same in a hole transport layer, and the hole transport material according to the present invention has a solar cell including PCE when compared to a spirobifluorene type hole transport material of the prior art. There are advantages in that the performance of the battery device is better and it has stability without deterioration for a long period of time.

Description

Hole transport material for solar cell and solar cell including the same

The present invention relates to a hole transport material for a solar cell and a solar cell including the same.

Due to concerns about depletion of fossil fuels, global warming and climate change due to their abuse, and safety concerns that exist in nuclear energy, the need for photovoltaic power generation, which is a sustainable energy, is being demanded more than ever.

Solar cell technology is a technology that directly converts light into electrical energy, and most of the solar cells in practical use are inorganic solar cells using inorganic materials such as silicon. However, since inorganic solar cells have high manufacturing costs and expensive materials due to complicated manufacturing processes, research on organic solar cells with low manufacturing costs and low material costs through relatively simple manufacturing processes has been actively conducted. However, in organic solar cells, the structure of BHJ is degraded by moisture or oxygen in the air, resulting in a rapid decrease in efficiency, which is a major problem in the stability of solar cells. However, there is a problem with the price going up.

Accordingly, perovskite solar cells are currently the closest to commercialization based on excellent photovoltaic characteristics, cost reduction and easy process among next-generation solar cells including dye-sensitized and organic solar cells, and full-scale research on stability and large-area is required. . Among them, the perovskite solar cell without a hole transport material showed lower charge extraction and charge recombination at the interface than the perovskite solar cell with a hole transport material, resulting in a drop in open-circuit voltage and charge rate.

Therefore, in order to show higher power conversion efficiency (PCE), the increase in charge extraction and unwanted charge recombination at the interface must be mitigated. To this end, hole transporting materials in perovskite solar cells , HTM) plays an important role.

Under these circumstances, perovskite solar cells have been actively studied in recent years due to their unique photochemical properties, strong light absorption ability, and high efficiency, and have recently achieved an efficiency of 20% or more. Although the transport ability of the hole transport material is one of the important points for the fabrication of such a high-efficiency device, there is a problem in that the materials used for the hole transport layer of the currently reported high-efficiency perovskite solar cell are limited.

One object of the present invention is to provide a hole transport material for a solar cell having excellent performance enough to replace existing hole transport materials.

Another object of the present invention is to provide a solar cell including the hole transport material for a solar cell in a hole transport layer.

According to one aspect of the present invention, there is provided a hole transport material for a solar cell represented by Formula 1 below:

[Formula 1]

In Formula 1,

Ar ₁ , Ar ₂ , Ar ₃ , and Ar ₄ are each independently a phenyl or naphthyl group substituted with 0 to 4 fluorine (F) atoms;

A ₁ , A ₂ , A ₃ , A ₄ , A ₁₁ , A ₁₂ , A ₁₃ , and A ₁₄ are each independently a single bond, an oxygen (O) atom, or a sulfur (S) atom,

R ₁ , R ₂ , R ₃ , R ₄ , R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms;

n ₁₁ , n ₁₂ , n ₁₃ , and n ₁₄ are each independently an integer of 0 to 4;

Provided, that Ar ₁ , Ar ₂ , Ar ₃ , and Ar ₄ are phenyl groups, and A ₁ , A ₂ , A ₃ , A ₄ , A ₁₁ , A ₁₂ , A ₁₃ , and A ₁₄ are oxygen (O) atoms. In this case, at least one of Ar ₁ , Ar ₂ , Ar ₃ , and Ar ₄ is substituted with one or more fluorine atoms.

According to another aspect of the present invention, a solar cell characterized in that the hole transport material is included in the hole transport layer is provided.

The hole transport material according to the present invention has excellent properties such as maintaining excellent stability without deterioration even for a long period of time, and a solar cell including the hole transport layer has excellent device performance such as PCE compared to conventional hole transport materials. It represents an improvement over the case of using transport materials.

1 is a diagram schematically showing the structure of a nip-perovskite solar cell prepared in Comparative Examples and Preparation Examples of the present invention.
2A to 2C show JV curves of solar cells manufactured according to Comparative Example and Preparation Example, and FIG. 2D is a graph showing PCE value distribution of each solar cell.
Figure 3a is for examining the long-term stability of solar cells manufactured according to Comparative Example and Preparation Example, and is a graph showing the change in PCE value over time, and Figures 3b to 3d show the change in JV curve over time will be.

Hereinafter, the present invention will be described in detail.

The terms used in this application are only used to describe specific embodiments and are not intended to limit the present invention. Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which the present invention belongs.

Throughout the specification, when a part "includes", "includes", or "has" a certain component, it means that it may further include other components unless otherwise specifically defined.

Throughout the specification, "perovskite solar cell" means a solar cell comprising an organic-inorganic halide material having a perovskite crystal structure.

According to one aspect of the present invention, there is provided a hole transport material for a solar cell, specifically a hole transport material for a perovskite solar cell, represented by Formula 1 below:

[Formula 1]

In Formula 1, Ar ₁ , Ar ₂ , Ar ₃ , and Ar ₄ are each independently a phenyl or naphthyl group substituted with 0 to 4 fluorine (F) atoms; Specifically, each may be independently substituted with 0 to 2 fluorine atoms; More specifically, each independently may be a phenyl group substituted with 0 to 2 fluorine atoms. According to one embodiment, the material represented by Chemical Formula 1 may be one or more of Ar ₁ , Ar ₂ , Ar ₃ , and Ar ₄ substituted by one or two fluorine (F) atoms, and in another embodiment According to this, at least one of Ar ₁ , Ar ₂ , Ar ₃ , and Ar ₄ may be a phenyl group substituted with one or two fluorine (F) atoms.

Further, in Formula 1, A ₁ , A ₂ , A ₃ , A ₄ , A ₁₁ , A ₁₂ , A ₁₃ , and A ₁₄ are each independently a single bond, an oxygen (O) atom, or a sulfur (S ) is an atom; Specifically, each independently may be a single bond or an oxygen atom. Specifically, A ₁ , A ₂ , A ₃ , and A ₄ may be identical to each other, and A ₁₁ , A ₁₂ , A ₁₃ , and A ₁₄ may be identical to each other, provided that A ₁ , A ₂ , and A The set of ₃ and A ₄ and the set of A ₁₁ , A ₁₂ , A ₁₃ , and A ₁₄ may be the same as or different from each other. According to one embodiment, in the material represented by Formula 1, at least one of A ₁ , A ₂ , A ₃ , A ₄ , A ₁₁ , A ₁₂ , A ₁₃ , and A ₁₄ is an oxygen (O) atom or a sulfur (S) atom. may be According to another embodiment, the material represented by Chemical Formula 1 includes a set of A ₁ , A ₂ , A ₃ , and A ₄ and a set of A ₁₁ , A ₁₂ , A ₁₃ , and A ₁₄ in which one set is an oxygen atom, and the other set is an oxygen atom. One set can be oxygen atoms or single bonds.

Further, in Formula 1, R ₁ , R ₂ , R ₃ , R ₄ , R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; Specifically, it may be a hydrogen atom or a branched or straight chain alkyl group having 1 to 4 carbon atoms. Specifically, R ₁ , R ₂ , R ₃ , and R ₄ may be identical to each other, and R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ may be identical to each other, provided that R ₁ , R ₂ , R The set of ₃ and R ₄ and the set of R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ may be the same as or different from each other. According to one embodiment, in the material represented by Formula 1, R ₁ , R ₂ , R ₃ , and R ₄ are each independently an alkyl group having 1 to 8 carbon atoms, and R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ are each independently , a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; Or R ₁ , R ₂ , R ₃ , and R ₄ are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. It may be an alkyl group.

In addition, in Formula 1, n ₁₁ , n ₁₂ , n ₁₃ , and n ₁₄ are each independently an integer of 0 to 4; Specifically, each independently may be an integer of 0 to 2. According to one embodiment, n ₁₁ , n ₁₂ , n ₁₃ , and n ₁₄ may be 0.

According to one embodiment of the present invention, the material represented by Chemical Formula 1 may be represented by Chemical Formula 2:

[Formula 2]

In Formula 2,

A ₁ , A ₂ , A ₃ , A ₄ , A ₁₁ , A ₁₂ , A ₁₃ , A ₁₄ , R ₁ , R ₂ , R ₃ , R ₄ , R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , n ₁₁ , n ₁₂ , n ₁₃ , and n ₁₄ are as defined in Formula 1 above,

n ₁ , n ₂ , n ₃ , and n ₄ are each independently an integer of 0 to 4;

However, when A ₁ , A ₂ , A ₃ , A ₄ , A ₁₁ , A ₁₂ , A ₁₃ , and A ₁₄ are oxygen (O) atoms, at least one of n ₁ , n ₂ , n ₃ , and n ₄ is an integer greater than or equal to 1.

According to one embodiment of the present invention, in Formula 2, A ₁ , A ₂ , A ₃ , A ₄ , A ₁₁ , A ₁₂ , A ₁₃ , and A ₁₄ are the same as each other, and an oxygen (O) atom or sulfur (S) is an atom, R ₁ , R ₂ , R ₃ , R ₄ , R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ are the same as each other, are an alkyl group having 1 to 8 carbon atoms, n ₁ , n ₂ , n ₃ , n ₄ , n ₁₁ , n ₁₂ , n ₁₃ , and n ₁₄ are integers from 0 to 2, provided that n ₁ , n ₂ , n ₃ , n ₄ , n ₁₁ , n ₁₂ , n ₁₃ , and n At least one of ₁₄ may be an integer of 1 or 2.

In addition, according to another embodiment of the present invention, the material of Chemical Formula 1 may be represented by the following Chemical Formula 3:

[Formula 3]

In Formula 3,

A ₁ , A ₂ , A ₃ , A ₄ , A ₁₁ , A ₁₂ , A ₁₃ , A ₁₄ , R ₁ , R ₂ , R ₃ , R ₄ , R ₁₁ , R ₁₂ , R ₁₃ , R ₁₄ , n ₁₁ , n ₁₂ , n ₁₃ , and n ₁₄ are as defined in Formula 1 above,

n ₁ , n ₂ , n ₃ , and n ₄ are each independently an integer of 0 to 4.

According to another embodiment of the present invention, the hole transport material of the present invention may be selected from the group consisting of Chemical Formulas 4 to 10:

[Formula 4]

[Formula 5]

[Formula 6]

[Formula 7]

[Formula 8]

[Formula 9]

[Formula 10]

The hole transport material according to the present invention can be synthesized through an amination reaction, specifically through a coupling reaction between an aryl halide and an amine under a Pd catalyst, and more specifically through a Buchwald-Hartwig C-N coupling reaction. [Scheme 1] schematically shows a method for preparing a hole transport material according to an embodiment of the present invention:

[Scheme 1]

Examples of the diphenylamine derivative in [Scheme 1] include the following derivatives:

According to another aspect of the present invention, a solar cell characterized in that the hole transport material is included in the hole transport layer is provided.

According to one embodiment of the present invention, the solar cell may be a perovskite solar cell. Specifically, the solar cell includes a first electrode; a photoactive layer disposed on the first electrode and including perovskite; and a hole transport layer disposed on the photoactive layer. The solar cell may further include a second electrode on the hole transport layer; An electron transport layer may be further included between the first electrode and the photoactive layer. In addition, in the solar cell, the photoactive layer further includes a photoactive material other than the perovskite material, for example, a semiconductor material, or the photoactive layer includes an additional layer other than the perovskite layer. It may further include another layer including a photoactive material, for example a semiconductor layer.

In the solar cell, the first electrode may be one of an anode and a cathode, and the second electrode may be the other of an anode and a cathode. In addition, either or both of the first electrode and the second electrode may be coated on the substrate.

As a method of forming the hole transport layer, the hole transport material is dissolved in a solvent or dispersed in a dispersion medium, followed by a spin coating method, a spray coating method, a screen printing method, a bar coating method, an inkjet printing method, and a slot die coating method. It may be formed by, for example, or may be formed by thermal evaporation or sputtering under vacuum.

Hereinafter, the present invention will be described in more detail with reference to examples to aid understanding of the present invention. However, the following examples are provided to more easily understand the present invention, and the content of the present invention is not limited by the following examples.

Synthesis Example 1. Synthesis of Spiro-mF (Formula 4)

(1) Synthesis of DPA-mF

To a two-neck round bottom flask, p-anisidine (3 g, 24.36 mmol), 4-bromo-2-fluoro-1-methoxybenzene (5.49 g, 26.79 mmol), tri-tert-butylphosphonium tetra Fluoroborate (212 mg, 0.73 mmol), and sodium tert-butoxide (4.68 g, 48.72 mmol) were dissolved in dry toluene (40 mL) and purged with argon for 15 minutes. Then, 446 mg of tris(dibenzylideneacetone)dipalladium(0) (0.49 mmol) was added to the reaction mixture, which was then purged again with argon for 20 minutes. The reaction mixture was then stirred overnight at 120 °C. After quenching the reaction by adding water, the mixture was extracted with ethyl acetate. The organic layer was dried over anhydrous MgSO4 and the solvent was removed under reduced pressure. The crude product was purified by silica gel column chromatography using hexane/ethyl acetate (9:1, v/v) as eluent to give DPA-mF as a yellow liquid (5.2 g, 86.3% yield).

(2) Synthesis of Spiro-mF (Formula 4)

2,2',7,7'-tetrabromo-9,9'-spirobifluorene (500 mg, 0.79 mmol), DPA-mF (840.7 mg, 3.40 mmol), tri- tert-Butylphosphonium tetrafluoroborate (13.8 mg, 0.047 mmol), and sodium tert-butoxide (456.5 mg, 4.75 mmol) were dissolved in dry toluene (40 mL) and purged with argon for 15 minutes. Then, 28.9 mg of tris(dibenzylideneacetone)dipalladium(0) (0.032 mmol) was added to the reaction mixture, which was then purged again with argon for 20 minutes. The reaction mixture was then stirred overnight at 120 °C. After quenching the reaction by adding water, the mixture was extracted with ethyl acetate. The organic layer was dried over anhydrous MgSO ₄ and the solvent was removed under reduced pressure. Spiro-mF was obtained as a solid by purifying the crude product by silica gel column chromatography using hexane/ethyl acetate (2:1, v/v) as eluent. The resulting solid was dissolved in THF and mixed with hydrazine hydrate. After stirring vigorously, the solution was precipitated in methanol (200 mL), filtered, and washed with methanol. Drying in a high vacuum oven afforded the desired product spiro-mF as a pale yellow solid (550 mg, 53.7% yield).

Synthesis Example 2. Synthesis of Spiro-oF (Formula 5)

(1) Synthesis of DPA-oF

DPA-oF was synthesized according to the same procedure as in Synthesis Example 1-(1) of DPA-mF, except that 4-bromo-3-fluoro-1-methoxybenzene was used. A green liquid was obtained (4.9 g, 81.3% yield).

(2) Synthesis of Spiro-oF (Formula 5)

Spiro-oF was synthesized according to the same procedure as in Synthesis Example 1-(2) of spiro-mF, except that DPA-oF was used instead of DPA-mF. A pale yellow solid was obtained (513 mg, 50.1% yield).

Synthesis Example 3. Synthesis of Spiro-TTBF (Formula 6)

(1) Synthesis of F-methylDPA

F-methylDPA was synthesized according to the same procedure as in Synthesis Example 1-(1) of DPA-mF, except that p-toluidine and 4-bromo-2-fluorotoluene were used. A white solid was obtained (5.03 g, 84.3% yield). 1H NMR (400 MHz, DMSO ^- d6), δ (ppm): 8.08 (s, 1H), 7.06 (m, 3H), 6.96 (m, 2H), 6.71 (m, 2H), 2.22 (s, 3H) ), 2.11 (s, 3H).

(2) Synthesis of Spiro-TTBF (Formula 6)

Spiro-TTBF was synthesized according to the same procedure as in Synthesis Example 1-(2) of spiro-mF, except that F-methylDPA was used instead of DPA-mF. Spiro-TTBF was obtained as a solid by purifying the crude product by silica gel column chromatography using hexane/methylene chloride (2:1, v/v) as eluent. A pale yellow solid was obtained (468 mg, 50.6% yield). 1H NMR (400 MHz, DMSO ^- d6 ), δ (ppm): 7.64 (d, 4H), 7.08 (m, 4H), 6.85 (m, 4H), 6.54 (m, 4H), 6.35 (m, 4H) ), 2.26 (s, 12H), 2.14 (s, 12H).

Synthesis Example 4. Synthesis of Spiro-S (Formula 7)

(1) Synthesis of S-DPA

S-DPA was synthesized according to the same procedure as in Synthesis Example 1-(1) of DPA-mF, except that 4-methylthioaniline and 4-bromothioanisole were used. A yellow solid was obtained (4.54 g, 81.2% yield). ¹ H NMR (400 MHz, DMSO- d6 ), δ (ppm): 8.18 (s, 1H), 7.18 (d, 4H), 6.99 (d, 4H), 2.39 (s, 6H).

(2) Synthesis of Spiro-S (Formula 7)

Spiro-S was synthesized according to the same procedure as in Synthesis Example 1-(2) of Spiro-mF, except that S-DPA was used instead of DPA-mF. A pale yellow solid was obtained (528 mg, 49.3% yield). 1H NMR (400 MHz, DMSO ^- d6 ), δ (ppm): 7.61 (d, 4H), 7.12 (d, 16H), 6.87 (d, 4H), 6.81 (d, 16H), 6.32 (s, 4H) ), 2.41 (s, 24H).

Synthesis Example 5. Synthesis of Spiro-Naph (Formula 8)

(1) Synthesis of DPA-Naph

DPA-Naph was synthesized according to the same procedure as in Synthesis Example 1-(1) of DPA-mF, except that 2-bromo-6-methoxynaphthalene was used. A brown solid was obtained (5.64 g, 83.5% yield). 1H NMR (400 MHz, DMSO ^- d6 ), δ (ppm): 7.93 (s, 1H), 7.65 (d, 1H), 7.54 (d, 1H), 7.23 (m, 1H), 7.16 (m, 2H) ), 7.11 (d, 2H), 7.02 (dd, 1H), 6.89 (d, 2H), 3.81 (d, 3H), 3.72 (d, 3H)

(2) Synthesis of Spiro-Naph (Formula 8)

Spiro-Naph was synthesized according to the same procedure as in Synthesis Example 1-(2) of Spiro-mF, except that DPA-Naph was used instead of DPA-mF. A pale yellow solid was obtained (583 mg, 51.7% yield). 1H NMR (400 MHz, DMSO ^- d6 ), δ (ppm): 7.73 (d, 4H), 7.56 (t, 8H), 7.28 (d, 8H), 7.11 (m, 8H), 7.02 (d, 8H) ), 6.95 (d, 8H), 6.84 (d, 4H), 6.42 (s, 4H), 6.41 (d, 3H), 3.89 (s, 12H) 3.80 (s, 12H).

Synthesis Example 6. Synthesis of Spiro-OP (Formula 9)

(1) Synthesis of DPA-OP

DPA-OP was synthesized according to the same procedure as in Synthesis Example 1-(1) of DPA-mF, except that 2-bromonaphthalene was used. A brown solid was obtained (4.85 g, 79.8% yield). 1H NMR (400 MHz, DMSO ^- d6 ), δ (ppm): 8.10 (s, 1H), 7.70 (t, 2H), 7.58 (d, 1H), 7.32 (m, 1H), 7.17 (m, 5H) ), 6.92 (m, 2H), 3.74 (s, 3H).

(2) Synthesis of Spiro-OP (Formula 9)

Spiro-OP was synthesized according to the same procedure as in Synthesis Example 1-(2) of Spiro-mF, except that DPA-OP was used instead of DPA-mF. A pale yellow solid was obtained (531 mg, 51.4% yield). 1H NMR (400 MHz, DMSO ^- d6 ), δ (ppm): 7.79 (d, 4H), 7.72 (d, 4H), 7.54 (m, 8H), 7.34 (m, 8H), 7.19 (m, 4H) ), 7.07 (dd, 4H), 7.01 (d, 8H), 6.90 (d, 8H), 6.85 (dd, 4H), 6.43 (d, 4H), 3.75 (s, 12H).

Synthesis Example 7. Synthesis of Spiro-ON (Formula 10)

(1) Synthesis of DPA-ON

DPA-ON was synthesized according to the same procedure as in Synthesis Example 1-(1) of DPA-mF, except that aniline and 2-bromo-6-methoxynaphthalene were used. A brown solid was obtained (6.56 g, 82.6% yield). 1H NMR (400 MHz, DMSO ^- d6 ), δ (ppm): 8.23 (s, 1H), 7.70 (d, 1H), 7.62 (d, 1H), 7.44 (m, 1H), 7.24 (m, 4H) ), 7.13 (m, 2H), 7.05 (m, 1H), 6.82 (m, 1H), 3.83 (s, 3H).

(2) Synthesis of Spiro-ON (Formula 10)

Spiro-ON was synthesized according to the same procedure as in Synthesis Example 1-(2) of Spiro-mF, except that DPA-ON was used instead of DPA-mF. A pale yellow solid was obtained (539 mg, 52.2% yield). 1H NMR (400 MHz, DMSO ^- d6 ), δ (ppm): 7.71 (d, 4H), 7.55 (dd, 8H), 7.33 (m, 4H), 7.25 (m, 12H), 7.05 (m, 12H) ), 6.93 (d, 8H), 6.85 (dd, 4H), 6.44 (d, 4H), 3.84 (s, 12H).

comparative example. Preparation of Comparative Perovskite Solar Cells

FTO glass (Asahi) was cleaned by ultrasonic cleaning for 15 minutes using RCA-2 (H ₂ O ₂ /HCl/H ₂ O = 1:1:5) to clean the surface. Thereafter, further washing was performed sequentially with acetone and isopropyl alcohol (IPA) for 15 minutes.

Dense TiO ₂ (c-TiO 2 ) by spray pyrolysis at 450 ° C. ₂ ) Layers were laminated. After forming the c-TiO ₂ layer, the substrate was stored at 450° C. for 1 hour to improve electrical properties. Thereafter, a mesoporous TiO ₂ (mp-TiO ₂ ) layer was deposited by spin coating a TiO ₂ paste containing TiO ₂ (ShareChem) having a size of about 50 nm on the c-TiO ₂ layer. The paste was diluted with 2-methoxyethanol/terpineol (78:22 w/w) 1:6 (g/g). The prepared substrate was further heated at 500 °C for 1 hour. For Li treatment of mp-TiO ₂ substrates, a 0.1 M solution of lithium bis(trifluoromethanesulfonyl)imide (Li-TFSI) in acetonitrile was spin coated at 3000 rpm for 30 seconds. Then, the Li-treated substrate was sintered at 500° C. for 1 hour. To fabricate perovskite solar cells, 1,550 mg mL ^-1 FAPbI ₃ and 61 mg MACl were dissolved in a mixture of DMF and DMSO (4:1 volume ratio). 70 μL of the filtered solution was spin-coated at 8000 rpm onto the mp-TiO ₂ layer. After spinning using a pipette, 1 mL diethyl ether was added dropwise for 10 seconds. The film was annealed at 150° C. for 10 minutes on a hot plate. After cooling the substrate, 20 mM of n-octylammonium iodide was spin-coated on the perovskite layer at 3000 rpm and the film was heated at 100° C. for 1 min. Spiro-OMeTAD (2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene) in chlorobenzene (Lumtech) (90.9 mg mL ⁻¹ ), 39 μL 4-tert-butylpyridine (tBP), 23 μL Li-TFSI (516 mg mL ⁻¹ acetonitrile), and 10 μL tris[2-(1H-pyrazol-1-yl) The hole transport material was prepared using -4-tert-butylpyridine]-cobalt(III)-tris[bis-(trifluoromethylsulfonyl)imide] (FK209, Lumtech) (395 mg mL ^-1 acetonitrile). prepared and stacked. Finally, a gold counter electrode was deposited on the substrate by thermal evaporation. A back contact and a front contact were formed from a 70 nm thick Au film deposited by vapor deposition at a pressure of 10 ⁻⁶ Torr.

Preparation Example 1. Preparation of perovskite solar cell of the present invention

Comparison above, except that spiro-mF (Formula 4) (90.9 mg mL ^-1 ), 15-32 μL of Li-TFSI, 39 μL of tBP, and 10 μL of FK209 were used to prepare the hole transport material. A perovskite solar cell was prepared in the same manner as in the example.

Preparation Example 2. Preparation of perovskite solar cell of the present invention

Spiro-oF (Formula 5) (90.9 mg mL ^-1 ), 15 to 32 μL of Li-TFSI, 39 μL of tBP, and 10 μL of FK209 were used to prepare the hole transport material, Spiro-oF After addition of tBP for dissolution, the spiro-oF solution was heated at 70 °C for 30 minutes and after cooling, Li-TSFI and FK209 were added in the same manner as in the comparative example, except that the perovskite solar A battery was made.

1 schematically shows the structure of n-i-p-perovskite solar cells prepared in Comparative Examples and Preparation Examples of the present invention.

Experimental Example 1. Photovoltaic Characteristics Analysis Experiment (Solar Cells of Comparative Example and Preparation Examples 1 and 2)

A solar cell was manufactured according to the Comparative Example and Manufacturing Example, and current density ^- voltage (JV ) curve was measured. At this time, the light intensity was calibrated using a Si reference electrode (certified by NREL) before measurement, there was no light penetration before potential scan, and the JV curve was reverse scan (short circuit at forward bias 1.2 V). to 0 V) and forward scan (forward bias 0 V to short circuit 1.2 V). The step voltage was fixed at 100 mV. The analysis results for parameters such as open circuit voltage (V _OC ), short circuit current density (J _SC ), charging factor (FF), and power conversion efficiency (PCE) are shown in [FIG. 2a] to [FIG. 2d]. , and the results are summarized in Table 1 below.

[Table 1]

In all cases, a small hysteresis was observed between the reverse scan and the forward scan of the JV scan. In the area of 0.0819 cm ² , the comparative device exhibited a short circuit current density (J _SC ) of 26.04 mA cm ⁻² , an open circuit voltage (V _OC ) of 1.152 V, a charge factor (FF) of 78.13%, and a maximum PCE of 23.44%. , these characteristic values were comparable to those reported as the highest PCE of perovskite solar cells in the prior art.

Compared to the device of the comparative example, both of the devices of the preparation examples using the fluorinated hole transport material according to the present invention have almost identical (J _SC ) values of 26.34 to 26.35 mA cm ⁻² and excellent V _OC values of over 1.16 V. showed up The device using the Spiro-mF of Preparation Example 1 showed a slightly higher FF (80.90%) than the other devices, and consequently showed the highest PCE of 24.82%.

Experimental Example 2. Additional photovoltaic characterization experiments (substances of Formulas 6, 7, and 8)

After Experimental Example 1 described above, a solar cell was fabricated using Spiro-Naph (a material represented by Chemical Formula 8), Spiro-TTBF (a material represented by Chemical Formula 6), and Spiro-S (a material represented by Chemical Formula 7) as hole transport materials. After that, the photovoltaic properties were measured. As a result, in the case of Spiro-Naph, the Voc value was 1.16 V, the J _SC value was 25.97 mA cm ^-2 , the FF value was 80.67%, the PCE value was 24.43%, and the PCE _avg value was 23.59%.

In the case of Spiro-TTBF and Spiro-S, a solar cell having a structure different from that in the Preparation Example was fabricated, and at this time, the comparative material (Spiro-OMeTAD (2,2',7,7'-tetrakis [N, Solar cells using N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene) show lower performance of less than 10%, whereas similar structures using spiro-TTBF and spiro-S It was confirmed that a high efficiency of 10% or more can be achieved in a solar cell.

Experimental Example 3. Long-term stability test

In order to investigate the deterioration of the perovskite film, long-term stability was tested using three devices of Comparative Example and Preparation Example 1 and 2 that were not encapsulated at -50% RH. The results are shown in [Fig. 3a] to [Fig. 3d]. The comparative device dropped from 23.21% to 13.74% after 500 hours, which is approximately 60% of the original PCE. On the other hand, both the devices of Preparation Example 1 and Preparation Example 2 using the fluorinated material according to the present invention had very stable PCE values, showing very high PCE value retention (>87%) even during the same measurement period as the comparative example. .

The above description of the present invention is for illustrative purposes, and those skilled in the art can understand that it can be easily modified into other specific forms without changing the technical spirit or essential features of the present invention. will be. Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting.

Claims (11)

delete delete delete delete delete delete A hole transport material for a solar cell, characterized by being represented by the following formula (3):
[Formula 3]

In Formula 3,
A ₁ , A ₂ , A ₃ , A ₄ , A ₁₁ , A ₁₂ , A ₁₃ , and A ₁₄ are each independently a single bond, an oxygen (O) atom, or a sulfur (S) atom,
R ₁ , R ₂ , R ₃ , R ₄ , R ₁₁ , R ₁₂ , R ₁₃ , and R ₁₄ are each independently a hydrogen atom or an alkyl group having 1 to 8 carbon atoms;
n ₁₁ , n ₁₂ , n ₁₃ , and n ₁₄ are each independently an integer of 0 to 4;
n ₁ , n ₂ , n ₃ , and n ₄ are each independently an integer of 0 to 4. According to claim 7,
A hole transport material for a solar cell, characterized in that it is selected from the group consisting of Formulas 8 to 10 below:
[Formula 8]

[Formula 9]

[Formula 10]

According to claim 7,
A hole transport material for a solar cell, characterized in that it is used in a perovskite solar cell. A solar cell comprising the hole transport material according to any one of claims 7 to 9 in a hole transport layer. According to claim 10,
a first electrode; a photoactive layer disposed on the first electrode and including perovskite; and a hole transport layer disposed on the photoactive layer.

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