JP2016100478A - Hole transport layer material and solar cell using hole transport layer material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hole transport layer material having excellent hole transportability, and excellent in durability inexpensively, and to provide a solar cell having high photoelectric conversion efficiency by using the hole transport layer material.SOLUTION: By giving a spiro ring structure in a molecule, a material having excellent hole transportability and high planarity of molecule, and thereby ensuring good electrical coupling between π-conjugated molecules, when superposing the molecules, is found. When using the hole transport layer material in the hole transport layer of hybrid solar cell, excellent hole transportability is obtained, and the solar cell performance is enhanced.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hole transport layer material and a solar cell using the hole transport layer material.

  Solar cells generally use silicon, compound semiconductors, organic semiconductors, etc., but in addition to high light collection capability, organic and inorganic hybrid types that can be made thinner and less expensive Solar cells are attracting attention.

Non-Patent Document 1 discloses a glass substrate with a transparent conductive film, a recombination prevention layer composed of a dense titanium dioxide (TiO ₂ ) film, and lead iodide (PbI ₂ ) as a dye that generates electrons when excited by light. And a hybrid solar cell comprising an electrolytic layer formed by adsorbing methylammonium iodide (CH ₃ NH ₃ I) on porous titanium dioxide (TiO ₂ ), a hole transport layer, and an electrode Has been.

This electrolytic layer is manufactured using a two-step process in which PbI ₂ is infiltrated into the pores of porous TiO ₂ using a spin coating method and then immersed in a solution containing CH ₃ NH ₃ I. As a result, crystals of perovskite dye (CH ₃ NH ₃ PbI ₃ ) are promptly generated, so that the photoelectric conversion efficiency is improved.

In addition, as a hole transport layer material used for the hole transport layer, 2,2 ′, 7,7′-tetrakis (N, N′-di-p-methoxyphenylamino) -9 represented by the following general formula (A): 9'-spirobifluorene (2,2 ', 7,7'-tetrakis (N, N'-di-p-methoxyphenylamine) -9,9'-spirobifluorene (generic name "Spiro-OMeTAD") Is used)). Perovskite dye crystals absorb light and generate electrons and holes. Holes are transported to the counter electrode by the hole transport layer material, and electricity is generated by repeating a cycle in which electrons move to the photoelectrode.

Burschka, J. et al, Sequential deposition as a route to high-performance perovskite-sensitized solar cells, Nature, 2013.07.10, volume499, p316-319, doi: 10.1038 / nature12340

  As described above, the hybrid solar cell has a high light collecting ability and has high power generation performance even under weak light energy such as indoors. Therefore, it is expected to be used in various environments. On the other hand, Spiro-OMeTAD used as a hole transport layer material in the hybrid solar cell of Non-Patent Document 1 has a problem that the molecular structure is bulky, and thus it is difficult to obtain electrical contact between molecules. . Therefore, it functions as a hole transport layer by adding a cobalt complex or the like as a dopant. Therefore, the performance of the solar cell is changed depending on the addition amount of the dopant and the mixing condition (concentration distribution), and it is difficult to stably exhibit the same function.

  In addition, when Spiro-OMeTAD is laminated as a hole transport layer material, gaps are formed between adjacent molecules due to the molecular structure described above, and various molecules may be taken into the gaps. Therefore, when producing a hole transport layer by Spiro-OMeTAD, for example, Spiro-OMeTAD is mixed with a dopant or the like, this mixture is dissolved in a solvent, applied, and then heated to evaporate the solvent. However, when solvent molecules are taken into the gaps between Spiro-OMeTAD molecules, it is difficult to completely remove the molecules, and as a result, the solar cell performance is not stable. Moreover, when constructed as a solar cell, water molecules in the environment may enter the gap during use, leading to a decrease in solar cell performance and durability.

  In addition, the synthesis of Spiro-OMeTAD has many reaction steps and requires many steps for purification, resulting in an increase in the cost of Spiro-OMeTAD.

  Accordingly, an object of the present invention is to provide a hole transport layer material having excellent hole transportability and excellent durability at low cost. Another object of the present invention is to provide a solar cell with high battery performance using the hole transport layer material.

  As a result of intensive studies to solve the above problems, the present inventors have found that a hole transport layer material having a spiro ring structure in the molecule has a high molecular flatness, and thus when molecules are stacked, a π-conjugated system, etc. It has been found that the electrical coupling between the molecules can be ensured satisfactorily and has an excellent hole transport property. Further, when the hole transport layer material is used for a hole transport layer of a hybrid solar cell or the like, the hole transport layer material has excellent hole transport properties, and thus the battery performance is improved, and the present invention is It came to be completed.

The characteristic structure of the hole transport layer material according to the present invention is a compound represented by the following general formula (1).
In (formula ^{(1), n 1, n} 2, n 3, and ^{n 4} is an integer independently ^{1~3, X 1, X 2,} X 3, and ^{X 4,} independently -O-, -S-, -Se- or -NH-, Y ¹ and Y ² are independently -S-, -Se- or -NH-, and A ¹ , A ² , A ³ and A ⁴ are independently phenylene, thiophenediyl, thiazolediyl, and B ¹ , B ² , B ³ , B ⁴ , B ⁵ , B ⁶ , B ⁷ , and B ⁸ are independently − OR ¹ , —SR ² , —SeR ³ , —NR ⁴ · R ⁵ , —NHR ⁶ , or —R ⁷ (where R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , and R ⁷ is independently a straight-chain or branched hydrocarbon group having 1 to 12 carbon atoms).

A preferred example is a compound represented by the following general formula (2).

  According to the said structure, the hole transport layer material which has the outstanding hole transport property which can capture | acquire and move a hole stably and efficiently can be provided. The hole transport layer material of this configuration can exhibit good hole transport properties without adding a dopant, and has excellent characteristics in terms of durability.

  Specifically, in the hole transport layer material of this configuration, the spiro carbon atom is positioned at the center of the spiro ring structure, and the spiro ring structure absorbs strain, so that the planarity of the molecule as a whole is enhanced. As a result, bonds between molecules due to weak interaction are formed, electrical bonds between molecules are ensured, and good hole transport properties can be exhibited. As described above, the hole transport layer material of the present configuration has high molecular structure planarity, so that no voids are generated between the molecules, and other molecules that may cause a decrease in hole transport performance are the hole transport of the present invention. Problems such as mixing between molecules of the layer material can be prevented. Thereby, the hole transport performance is stable, and excellent performance can be exhibited in terms of durability.

  Furthermore, the hole transport layer material of this configuration has fewer reaction steps in the synthesis than the above-described Spiro-OMeTAD and is easy to purify, so the number of steps required for the synthesis can be reduced. For this reason, it is possible to synthesize at low cost, and as a result, it is possible to reduce the price of the solar cell itself.

  The characteristic configuration of the solar cell according to the present invention includes a substrate having a transparent conductive film, a recombination preventing layer for transferring electrons to the transparent conductive film and preventing reverse electron transfer, and a dye that generates the electrons when excited by light. An electrolyte layer formed by adsorbing to a porous semiconductor, a hole transport layer having the hole transport layer material through which holes generated from the dye pass, and a laminated body in that order, and through the transparent conductive film And an electrode composed of a counter electrode provided on the surface of the hole transport layer.

  Like this structure, photoelectric conversion efficiency improves by using the hole transport layer material which has the outstanding hole transport property for the hole transport layer of a solar cell. Furthermore, the durability of the solar cell is enhanced by the excellent durability of the hole transport layer material. As described above, the cell performance of the solar cell can be improved by the hole transport layer having the hole transport layer material.

It is a schematic cross section of a hybrid type solar cell. It is power generation explanatory drawing of a hybrid type solar cell. It is a figure which shows the suitable example of hole transport layer material. It is a figure which shows the suitable example of hole transport layer material. It is the figure which compared the molecular structure of hole transport layer material with the conventional molecular structure. It is the figure which compared the molecular structure of hole transport layer material with the conventional molecular structure. It is a figure which shows the synthetic scheme of hole transport layer material. This is a procedure for manufacturing a hybrid solar cell. It is a comparison figure which shows the performance curve of the solar cell when not adding a dopant to hole transport layer material. It is a comparison figure which shows the performance curve of the solar cell at the time of adding a dopant to hole transport layer material.

  Hereinafter, an embodiment of a hybrid solar cell 10 (an example of a solar cell, hereinafter referred to as a solar cell 10) using a hole transport layer material having a specific structure will be described based on the drawings. However, the present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the invention.

(Basic configuration)
As shown in FIG. 1, the solar cell 10 includes a substrate 2 having a transparent substrate 21 and a transparent conductive film 22, and is provided on the substrate 2, delivers electrons to the transparent conductive film 22, and transfers the hole transport layer 5 and the transparent conductive film. A recombination prevention layer 3 that separates the film 22 and prevents recombination (reverse electron transfer) between electrons and holes, and a dye 44 that is provided on the recombination prevention layer 3 and is excited by light to generate electrons. Is provided with a laminated body 11 composed of an electrolytic layer 4 formed by adsorbing a porous semiconductor 41 and a hole transport layer 5 provided on the electrolytic layer 4 and through which holes generated in the dye 44 pass. Further, an electrode provided on the surface of the recombination preventing layer 3 and composed of a photoelectrode 61 that emits electrons through the transparent conductive film 22 and a counter electrode 62 that is provided on the surface of the hole transport layer 5 and receives electrons. 6 is provided. The arrangement of the electrodes 6 is not particularly limited as long as electrons can be transferred, for example, the photoelectrode 61 is formed by conducting a wire connection to the transparent conductive film 22. Further, the counter electrode 62 may be protected by the transparent substrate 21 or the like in order to increase the durability of the solar cell 10.

  The transparent substrate 21 is made of a material having optical transparency. For example, a transparent glass substrate, a ground glass-like translucent glass substrate, a transparent resin substrate, or the like can be used. The transparent conductive film 22 may be made of, for example, fluorine-doped tin oxide (FTO), tin oxide (TO), tin-doped indium oxide (ITO), zinc oxide (ZnO), or aluminum-doped zinc oxide (AZO). .

A metal oxide is suitable for the recombination prevention layer 3 and the porous semiconductor 41. For example, titanium dioxide (TiO ₂ ), zinc oxide (ZnO), niobium oxide (Nb ₂ O ₅ ), tin dioxide (SnO ₂ ). Aluminum oxide (Al ₂ O ₃ ) or the like is used. In particular, titanium dioxide (TiO ₂ ) capable of securing a large surface area for adsorbing the dye 44 is preferable. In addition, the recombination preventing layer 3 is partially formed to extend to the transparent conductive film 22, and the transparent conductive film 22 is partitioned. Further, the recombination preventing layer 3 is formed with a dense insulating layer 31 so that electrons can pass in the stacking direction but hardly move in the lateral direction. That is, electrons entering from the recombination preventing layer 3 smoothly move in the lamination direction of the transparent conductive film 22 and are supplied to the photoelectrode 61, and are also prevented from moving to the counter electrode 62 by the insulating layer 31. do not do.

The dye 44 is composed of a compound composed of lead and a halogen element X (PbX ₂ , X = halogen element), methylammonium halide (CH ₃ NH ₃ X, as a representative example, methylammonium iodide (CH ₃ NH ₃ I: below) , MAI) or formamidinium hydride (CH2 = NHX) or a mixture thereof, specifically, lead halide (PbX ₂ ) is formed inside the pores of the porous semiconductor 41. After the permeated solution 42 is permeated and dried, it is immersed in a mixed solution 43 of MAI, so that crystals of perovskite dye 44 (CH ₃ NH ₃ PbI ₃ when X = I) are rapidly formed. As element X, iodine, bromine, chlorine, or the like can be used, but iodine having high form stability is preferably used.

  The hole transport layer 5 uses a hole transport layer material described later. For the electrode 6, for example, a simple substance or alloy of metal such as gold, platinum, silver, or copper, or an oxide conductor such as fluorine-doped tin oxide (FTO) or tin-doped indium oxide (ITO) can be used.

  Here, the principle that the solar cell 10 generates power will be described with reference to FIG. When light such as sunlight or room light enters the transparent substrate 21, the incident light is hardly absorbed and passes through the substrate 2 and the recombination preventing layer 3, and most of the light reaches the electrolytic layer 4. When the incident light reaching the electrolytic layer 4 is irradiated onto the dye 44, the dye 44 absorbs light energy and is excited. When the energy level of the dye 44 becomes higher than the conduction charge level of the metal oxide, which is the porous semiconductor 41, by this excitation, electrons are injected from the dye 44 into the porous semiconductor 41. The injected electrons are collected by the photoelectrode 61 through the recombination prevention layer 3.

  On the other hand, the holes generated in the dye 44 reach the counter electrode 62 through the hole transport layer 5 and recombine with electrons that have passed through the external load 7. That is, since a potential gradient is generated between the photoelectrode 61 and the counter electrode 62, electric power can be supplied by connecting the external load 7 between the two electrodes.

[Hole transport layer material]
The molecular structure of the hole transport layer material according to the present embodiment has a spiro ring structure in which one carbon atom is shared and bonded as a central structure and a hetero ring structure adjacent to the spiro ring structure and degenerately bonded. .

The hole transport layer material is represented by the following general formula (1).

In the general formula ^{(1), n 1, n} 2, n 3, and n ⁴ are independently an integer of from 1 to 3, the number of linear hydrocarbon chain. By comprising in this way, the two cyclic structures connected sharing the spiro carbon atom become a 7-11 membered ring. n ¹ , n ² , n ³ , and n ⁴ may be partially different as long as they are integers of 1 to 3, but are preferably composed of the same number. When composed of the same number, when n ¹ , n ² , n ³ , and n ⁴ are 1, two cyclic structures are 7-membered rings, and when 2 are 9-membered rings, 3 Is an 11-membered ring, particularly preferably a 7-membered ring.

X ¹ , X ² , X ³ and X ⁴ are independently —O—, —S—, —Se— or —NH—. By comprising in this way, a spiro cyclic structure has a hetero atom selected from an oxygen atom, a nitrogen atom, a serine atom, and a nitrogen atom. Each may be composed of different heteroatoms, or part of them may be composed of different heteroatoms, but preferably composed of the same heteroatoms. Particularly preferably, a spiro ring structure containing an oxygen atom is formed.

Y ¹ and Y ² are independently —S—, —Se—, or —NH—. The compound of the general formula (1) has two degenerate heterocyclic structures in which two carbon atoms are shared and degenerately bonded to the spirocyclic structure. Has a thiophene ring containing sulfur as a hetero atom, a selenophene ring containing a serine atom, and a pyrrole ring structure containing a nitrogen atom. The two degenerate heterocyclic structures may be composed of different heterocyclic structures containing different heteroatoms, but preferably have the same cyclic structure. Particularly preferred is a thiophene ring structure containing sulfur as a heteroatom.

A ¹ , A ² , A ³ , and A ⁴ are independently a phenylene group, a thiophenediyl group, or a thiazolediyl group. By comprising in this way, the substituted diphenylamino group and the heterocyclic ring degenerately bonded to the spiro ring which is the central structure are connected via a phenylene group, a thiophenediyl group, or a thiazolyl group. A ¹ , A ² , A ³ and A ⁴ may be different groups or partially different groups, but are preferably the same group.
Here, the phenylene group is a divalent group formed by removing two hydrogen atoms from the carbon atom of the benzene ring. There are three types of phenylene groups depending on the positional relationship of the two hydrogen atoms to be removed, and any of these may be used. Specifically, there are 1,2-phenylene in which the two hydrogen atoms to be removed are in the ortho position, 1,3-phenylene in the meta position, and 1,4-phenylene in the para position. 4-phenylene. A thiophenediyl group is a divalent group formed by removing two hydrogen atoms from a carbon atom of a thiophene ring. Depending on the positional relationship of the two hydrogen atoms removed, there are thiophene-2,3-diyl, thiophene-2,4-diyl, thiophene-2,5-diyl, thiophene-3,4-diyl, Although it may be present, thiophene-2,5-diyl is preferable. A thiazolediyl group is a divalent group formed by removing two hydrogen atoms from a carbon atom of a thiazole ring. Thiazole has a sulfur atom at the 1-position and a nitrogen atom at the 3-position of the 5-membered ring. Depending on the positional relationship of the two hydrogen atoms to be removed, there are thiazole-2,4-diyl, thiazole-2,5-diyl, thiazole 4,5-diyl, which may be any of these, but preferably Thiazole-2,5-diyl. Further, as an isomer of thiazole, an isothiazole having a sulfur atom at the 1-position and a nitrogen atom at the 2-position of a 5-membered ring may be a divalent group derived from such an isothiazole ring. Depending on the positional relationship of the two hydrogen atoms to be removed, there are isothiazole-3,4-diyl, isothiazole-3,5-diyl, isothiazole 4,5-diyl, and any of these may be used.

B ¹ , B ² , B ³ , B ⁴ , B ⁵ , B ⁶ , B ⁷ , and B ⁸ are independently -OR ¹ , -SR ² , -SeR ³ , -NR ⁴ · R ⁵ , -NHR ^6, or a -R ^7. Here, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ and R ⁷ are each independently a linear or branched hydrocarbon group having 1 to 12 carbon atoms. Here, the straight chain or branched hydrocarbon group having 1 to 12 carbon atoms is preferably a straight chain or branched saturated hydrocarbon group having 1 to 12 carbon atoms, for example, a straight chain or branched chain having 1 to 12 carbon atoms. It is an alkyl group. B ¹ , B ² , B ³ , B ⁴ , B ⁵ , B ⁶ , B ⁷ , and B ⁸ may be different groups or partially different groups, but are preferably the same group.
Examples of the alkyl group include, but are not limited to, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, and n-pentyl. Group, isopentyl group, neopentyl group, t-pentyl group, n-pentyl group, t-pentyl group, neopentyl group, isopentyl group, s-pentyl group, n-hexyl group, isohexyl group, s-hexyl group, t-hexyl Group, n-heptyl group, isoheptyl group, s-heptyl group, t-heptyl group, n-octyl group, isooctyl group, s-octyl group, t-octyl group, neooctyl group, n-nonyl group, isononyl group, s -Nonyl, t-nonyl, neononyl, n-decyl, isodecyl, s-decyl, t-decyl, neodecyl, n-undecyl, isoundecyl, s-decyl, t-decyl Neoundecyl Group, n-dodecyl group, isododecyl group, s-dodecyl group, t-dodecyl group, neododecyl group and the like can be used. “N” is an abbreviation for “normal”, “s” is an abbreviation for “sec” and “secondery”, and “t” is an abbreviation for “tert” and “tertiary”.

[Preferred examples of hole transport layer material]
Preferred examples of the hole transport layer material are 4,4 ', 4'',4'''-(2H,2'H, 4H, 4'H-3,3'-spiro-bi [thieno [3,4 -b] [1,4] dioxepine] -6,6 ', 8,8'-tetrayl) tetrakis (N, N-bis (4-methoxyphenyl) aniline, shown below as general formula (2). In the document, the hole transport layer material in the present embodiment may be referred to as “PST1”, but is not limited thereto.

  Furthermore, suitable examples of the hole transport layer material are shown in FIGS.

[Characteristics of hole transport layer material]
The hole transport layer material according to the present embodiment has an excellent hole transport property capable of capturing and moving holes stably and efficiently by having the specific structure. Moreover, this hole transport layer material has excellent characteristics in terms of durability. The hole transport layer material can be suitably used as the hole transport layer material of the hybrid solar cell 10, exhibits excellent hole transport properties as the hole transport layer material, and improves the photoelectric conversion efficiency and durability of the solar cell 10. Can contribute to the improvement of battery performance.

  The characteristic structure of the hole transport layer material according to this embodiment and the advantageous properties that are considered to be caused by this will be described in detail by taking PST1 shown in the general formula (2) as an example (see FIGS. 5 and 6).

  PST1 is located in the center of the spiro ring structure in which the spiro carbon atom is composed of two seven-membered rings. Since such a spiro ring structure absorbs strain, two thiophene ring structures (thieno groups) adjacent to the spiro ring structure are coordinated to occupy the same plane. As a result, the planarity of the molecule as a whole is enhanced (FIGS. 5A and 5B). This results in the formation of bonds between molecules due to weak interactions, electrical bonds between molecules (multiple CH / π hydrogen bonds), and short contacts between π / π molecules (π / π intermolecular). short contact) is secured (FIGS. 6A and 6B). Thereby, a favorable hole transport property is shown.

  When the conventional Spiro-OMeTAD uses a hole transport layer material, it is necessary to add a dopant having a function of improving hole transport efficiency. On the other hand, the hole transport layer material of this embodiment including PST1 can exhibit good hole transport properties without adding a dopant. As a result, the production of the solar cell 10 is simplified and the composition of the hole transport layer material is stable, so that the same performance can always be obtained.

  In addition, when the above-mentioned Spiro-OMeTAD was laminated as a hole transport layer, when immobilized on a substrate, there were gaps between molecules due to its molecular structure, and other molecules were mixed in ( (B) of FIG. 5, (c), (d) of FIG. 6). Specifically, Spiro-OMeTAD has a five-membered spiro ring structure at the center of the molecule, and the molecule is twisted by about 90%. Therefore, the molecular structure becomes bulky, solvent molecules enter between the molecular gaps to block hole transport, and the cobalt complex added as a dopant is dropped off, etc., and the hole transport property is stably and continuously exhibited. I couldn't. However, PST1 does not generate voids between molecules, and can prevent problems such as mixing of other molecules between molecules, and can ensure electrical coupling between molecules. Addition of dopant is not required. Thereby, the hole transport performance is stable, and excellent performance can be exhibited in terms of durability.

  Furthermore, PST1 has fewer reaction steps for synthesis than Spiro-OMeTAD described above and is easy to purify, so the number of steps required for synthesis can be reduced. For this reason, PST1 can be synthesized at a lower cost than Spiro-OMeTAD, and as a result, the price of solar cell 10 itself can be reduced.

[Method of synthesizing hole transport layer material]
The hole transport layer material synthesis method according to this embodiment can be easily synthesized with reference to the synthesis method described in Example 1 below. In addition, Example 1 shows an example of the synthesis | combining method of PST1 which is a suitable example of a hole transport layer material, It is not limited to this, It can synthesize | combine using another method suitably.

  By appropriately changing the reaction compounds and reagents, PST1 is the spiro ring structure heteroatom, the size of the spiro ring, the type of hetero ring degenerately bonded to the spiro ring structure, the species of substituent of the diphenylamine group, or Further, hole transport layer materials having different types of groups connecting the heterocycle and the diphenylamine group can be synthesized, and such hole transport layer materials are also included in this embodiment. For example, in FIG. 7A, the thiophene ring of 3,4-dimethoxythiophene, which is the starting material, can be changed to a selenophene ring, a pyrrole ring, or the like, and the hydrocarbon chain following the spiro carbon atom of pentaerythritol can be changed. The length and hydroxy group can be changed. 7B, the phenyl ring of 4-bromoaniline can be changed to a thiophene ring or a thiazole ring, and the methoxy group of 4-iodoanisole can be changed to an alkylsulfanyl group or an alkyl group. Can do.

Example 1
Hereinafter, as Example 1, a synthesis example of the hole transport layer material is shown. However, it is not limited to this embodiment.

  In this example, the synthesized hole transport layer material is referred to as “PST1” shown in the general formula (2). A synthesis scheme will be described with reference to FIG.

A. Synthesis route of thiophene-based spiro compounds (Step 1) Synthesis of TS
3,4-dimethoxythiophene (2.0 g, 0.014 mol), p-toluenesulphonic acid (0.26 g, 0.00138 mol), pentaerythritol (11.3 g, 0.083) Mol) was dissolved in toluene (250 ml) in a 500 ml round bottom flask. This was refluxed for 24 hours under a dry nitrogen stream, cooled to room temperature, and washed with pure water. Subsequently, the organic layer was separated and dried. After the resulting crude product mixture was purified using a silica gel column, the solvent was removed by evaporation under reduced pressure. The obtained solid was recrystallized using chloroform to obtain white TS crystals (yield 2.5 g, yield 61%).
The result of NMR analysis of the obtained TS was as follows.
¹ H NMR (400 MHz, chloroform d) δ 6.49 (s, 2H), 4.08 (s, 8H).
¹³ C NMR (CDCl ₃ ) δ (ppm): 50.67, 71.37, 105.39, 149.04.

(Step 2) Synthesis of BTS TS (0.5 g, 0.00169 mol) obtained in Step 1 was dissolved in 30 ml of chloroform, and N-bromosuccinimide (hereinafter sometimes referred to as “NBS”) was dissolved therein. ) (1.35 g, 0.0076 mol) in DMF (30 mL) was slowly added over 45 minutes. After further stirring at room temperature for 6 hours, the reaction solution was concentrated by reducing the pressure to evaporate the solvent. Pure water (200 mL) was added to this concentrate with stirring, and the resulting precipitate was filtered off. Subsequently, the precipitate was washed with water and then with methanol. The obtained crude product was purified by recrystallization using THF / MeOH (1/3) to obtain white crystals of BTS (yield 1.2 g, yield 76%).
The results of NMR analysis of the obtained BTS were as follows.
¹ H NMR (CDCl ₃ ) δ (ppm): 4.16 (s, 8H).
¹³ C NMR (CDCl ₃ ) δ (ppm): 146.07, 91.33, 71.03, 50.84.

B. Synthesis route of donor (Step 3) Synthesis of OMT Br For xylene (30 mL), 4-bromoaniline (5.00 g, 29.2 mmol), 4-iodoanisole (14.4 g, 61.3 mmol), CuI (0.28 g, 1.46 mmol), KOH (12.8 g, 228 mmol) and 1,10-phenanthroline (0.26 g, 1.46 mmol) are added and the reaction mixture is heated to 120 ° C. Heated. Heating and stirring were continued for 36 hours. Subsequently, the reaction mixture was allowed to cool to room temperature, diluted with CH ₂ Cl ₂ (200 mL), and then washed 4 times with 150 mL of pure water. The organic layer was dried using anhydrous MgSO ₄ and the solvent was evaporated under reduced pressure. The crude product was purified by column chromatography packed with silica gel to obtain OMT Br (yield 6.35 g, 57% yield) as a yellow oily liquid.
The results of NMR analysis of OMT Br were as follows.
¹ H NMR (400 MHz, CDCl ₃ ) δ 7.28-7.24 (m, 2H), 7.07-7.02 (m, 4H), 6.87-6.83 (m, 4H), 6.83-6.78 (m, 2H), 3.82 (s , 6H).

(Step 4) Synthesis of OMT BPIN OMT Br (2.0, 0.0052 mol), bis (pinacolato) diboron (1.6 g, 0.00625 mol), potassium acetate (1.5 g, obtained in Step 3) 0.0156 mol) was dissolved in dioxane (40.0 ml), and the gas was removed under a dry nitrogen stream for 20 minutes. Next, Pd ₂ dba ₃ (25 mg) and X-Phos (50 mg) were added simultaneously, and the mixture was heated to 80 ° C. and reacted for 12 hours. After completion of the reaction, the mixture was allowed to cool to room temperature and dried with MgSO ₄ . The crude product was purified by silica gel chromatography to obtain OMT BPIN (yield 1.5 g, yield 67%) as a yellow solid.
The results of NMR analysis of OMT BPIN were as follows.
¹ H NMR (400 MHz, CDCl ₃ ) δ 7.67-7.59 (m, 2H), 7.12-7.07 (m, 4H), 6.92-6.88 (m, 2H), 6.88-6.84 (m, 4H), 3.82 (s , 6H), 1.35 (s, 12H).

C. Synthesis route of PST1 (Step 5) Synthesis of PST1 OMT BPIN (1.1 g, 0.00245 mol) obtained in Step 4 and BTS (0.25 g, 0.00041 mol) obtained in Step 2 were added with toluene (30.0 ml), K ₂ After dissolving in CO ₃ aqueous solution (2M 10.0 ml) and removing gas for 30 minutes under a dry nitrogen stream, Pd (0) (100 mg) was added. The mixture was heated to 100 ° C. and stirring was continued for 24 hours. After completion of the reaction, the mixture was allowed to cool to room temperature, washed with water (100 ml) and then with brine (100 ml), and the organic layer was separated and dried. The crude product was purified by silica gel chromatography to obtain PST1 (yield 0.31 g, yield 50%) as a yellow solid.
The results of NMR analysis of PST1 were as follows.
¹ H NMR (400MHz, THFd8) δ 7.52 (d, = 8.5Hz J, 8H), 7.03 (d, = 8.6Hz J, 16H), 6.85 (m, J = 6.9Hz, 24H), 4.24 (s, 8H), 3.76 (s, 24H).
¹³ C NMR (101 MHz, THFd8) δ = 154.45, 145.75, 142.87, 138.76, 124.98, 124.56, 123.25, 118.11, 116.36, 112.61, 68.77, 52.76, 48.67.

[Production procedure of solar cell]
Next, a manufacturing procedure of the solar cell 10 will be described with reference to FIG.

  First, the transparent conductive film 22 is formed on the transparent substrate 21 to produce the substrate 2. The transparent conductive film 22 is laminated on the transparent substrate 21 by, for example, CVD (Chemical Vapor Deposition) or sputtering. Next, laser scribing is performed to form a recess 221 into which the insulating layer 31 is inserted, and then cleaning is performed. Next, the recombination prevention layer 3 is formed on the entire surface of the substrate 2 by ALD (atomic layer deposition method), SPD (spray pyrolysis method) or the like. Next, a porous semiconductor 41 that is a nanoparticle sintered layer is formed in the vicinity of the center on the masked substrate 2 and the recombination prevention layer 3. The porous semiconductor 41 is formed by diluting the nanoparticle paste with a solvent, applying and drying by spin coating or the like at a rotational speed of 4000 rpm to 6000 rpm, removing the masking, and heating at 450 ° C. to 550 ° C. The

Next, for example, an N, N-dimethylformamide solution 42 of lead iodide (PbI ₂ ) is prepared, dropped on the porous semiconductor 41, and then penetrated into the pores by spin coating at a rotational speed of 5000 rpm to 8000 rpm. And the excess solution is removed and dried at 60 to 120 ° C. (preferably 70 to 90 ° C.).

Next, the substrate 2, the recombination preventing layer 3, and the porous semiconductor 41 infiltrated with lead iodide are immersed in an isopropyl alcohol solution 43 (2 to 20 mg / ml) of MAI at 0 ° C. to 80 ° C. (preferably normal temperature). The perovskite dye 44 [(CH ₃ NH ₃ ) PbI ₃ ] is formed inside the pores of the porous semiconductor 41 and on the electrolytic layer 4 and then irrigated with a pure isopropyl alcohol solution to 60 ° C. to 120 ° C. (preferably 70 ° C. Dry at ~ 100 ° C.

  Next, 60 to 90 mg / ml of a chlorobenzene solution (including some additives) of the hole transport layer material of PST1 is dropped, and the excess solution is removed by spin coating, followed by drying. Finally, a thin film such as gold is attached to the surfaces of the recombination prevention layer 3 and the hole transport layer 5 by vacuum deposition or the like.

(Example 2)
Below, Example 2 in the solar cell 10 will be described. However, it is not limited to this embodiment.

First, a glass substrate (substrate 2) with a transparent conductive film in which fluorine-doped tin oxide (FTO) as a transparent conductive film is formed by CVD on a transparent glass plate as a transparent substrate 21 of 20 mm × 20 mm × 2 mm is prepared, and laser scribing is performed. The recess 221 was formed and washed. Next, a dense layer (thickness 150 nm) of titanium dioxide (TiO ₂ ) serving as the recombination preventing layer 3 was formed on the entire surface of the glass substrate with a transparent conductive film by SPD (spray pyrolysis method).

Next, a solution obtained by diluting a commercially available TiO ₂ nanoparticle paste four times with ethanol is added dropwise, applied onto the recombination prevention layer 3 by spin coating, dried at 80 ° C., and then sintered at 500 ° C. for 15 minutes. by, to form a TiO ₂ nanoparticle layer comprising a porous semiconductor 41 having a thickness of 300 nm. Further, this was immersed in an aqueous titanium tetrachloride solution (400 mmol / l) at 70 ° C. for 30 minutes, rinsed with pure water, and sintered at 500 ° C. for 30 minutes.

Next, an N, N-dimethylformamide solution 42 (1.2 mol / l) of lead iodide (PbI ₂ ) was adjusted and dropped, and lead iodide was infiltrated into the inside of the TiO ₂ nanoparticle layer by spin coating. And dried at 70 ° C. for 30 minutes.

Next, the substrate 2, the recombination preventing layer 3, and the porous semiconductor 41 containing lead dioxide are immersed in an 8 mg / ml methylammonium iodide (CH ₃ NH ₃ I) isopropyl alcohol solution 43 at room temperature for 15 minutes. The sample was sprinkled with a pure isopropyl alcohol solution, spin-coated, dried at 100 ° C. for 15 minutes, and then rapidly cooled to room temperature. This produced crystals of perovskite dye 44 [(CH ₃ NH ₃ ) PbI ₃ ].

  Next, FK209 (Tris (2- (1H-pyrazol-1-yl) -4-tert-butylpyridine) cobalt (III) Tris (bis (trifluoromethylsulfonyl) imide)), which is a cobalt dopant, is added, or the hole transport layer material PST1 or 60 μl of a chlorobenzene solution in which Spiro-OMeTAD 0.02M and FK-209 0.5 mM are dissolved is dropped, and the excess solution is removed by spin coating, followed by drying, whereby a hole transport layer 5 having a thickness of 210 nm is formed on the electrolytic layer 4. At this time, as a comparative example, a case in which the cobalt dopant FK209 was not added was also prototyped.Finally, a gold film was formed on the surface of the laminated body 11 in which these were laminated by a vacuum evaporation method, and the photoelectrode 61 was formed. The electrode 6 having a thickness of 100 nm and the counter electrode 62 was laminated.

  Next, performance evaluation of the solar cell 10 is performed. FIG. 9 is a comparison diagram of average battery performance when FK209 is added to a chlorobenzene solution of PST1 or Spiro-OMeTAD, and FIG. 10 is an average battery performance when FK209 is not added to a chlorobenzene solution of PST1 or Spiro-OMeTAD. FIG.

9 to 10 show open circuit voltage (Voc) -short-circuit current (Isc) characteristics representing battery performance. The open circuit voltage Voc is a voltage when no current flows through the solar cell 10, and the short circuit current Isc is a current when the voltage is 0V. Jsc in the figure is the short-circuit current density (mA / cm ² ) obtained by dividing the short-circuit current Isc by the effective light receiving area.

Table 1 shows the numerical values of the battery performance of the solar battery 10.
Here, the form factor FF (fill factor) is a curve factor obtained by dividing the maximum output Pmax at the point where the product of current and voltage is maximum by (Voc × Jsc), and PCE is (Voc × Jsc). × FF ÷ incident light intensity).

  9 to 10 and Table 1, when FK209 is added, the solar cell using the PST1 hole transport layer material has a lower short-circuit current than the solar cell using the Spiro-OMeTAD hole transport layer material. Although the density was shown, the open circuit voltage and the form factor were high, and as a result, the conversion efficiency was high. Moreover, in the solar cell using the hole transport layer material of Spiro-OMeTAD, when FK209 was not added, the open circuit voltage and the form factor were greatly reduced compared to the case where FK209 was added, and the conversion efficiency was greatly reduced.

  On the other hand, the solar cell using PST1 hole transport layer material has a lower open-circuit voltage and a smaller form factor when FK209 is not added than when FK209 is added. The decrease in efficiency was suppressed. In particular, the solar cell using the PST1 hole transport layer material when FK209 was not added had higher conversion efficiency than the solar cell using the Spiro-OMeTAD hole transport layer material when FK209 was added. From these, it was proved that the photoelectric conversion efficiency of the solar cell is greatly improved by using PST1 as the hole transport layer material.

[Other Embodiments]
In the embodiment described above, a hybrid solar cell is shown as an example of the solar cell 10 using the hole transport layer material of PST1, but this hole transport layer material is made of OPV (organic thin film solar cell), organic EL, and organic semiconductor. You may use for the used device.

  INDUSTRIAL APPLICABILITY The present invention can be used as a hole transport layer material used for a hybrid solar cell provided with a perovskite dye produced from an organic and inorganic hybrid compound.

2 Substrate 3 Recombination prevention layer 4 Electrolytic layer 5 Hole transport layer 6 Electrode 10 Solar cell 11 Laminate 41 Porous semiconductor 44 Dye 61 Photoelectrode 62 Counter electrode

Claims (3)

A hole transport layer material which is a compound represented by the following general formula (1).
In (formula ^{(1), n 1, n} 2, n 3, and ^{n 4} is an integer independently ^{1~3, X 1, X 2,} X 3, and ^{X 4,} independently -O-, -S-, -Se- or -NH-, Y ¹ and Y ² are independently -S-, -Se- or -NH-, and A ¹ , A ² , A ³ and A ⁴ are independently phenylene, thiophenediyl, thiazolediyl, and B ¹ , B ² , B ³ , B ⁴ , B ⁵ , B ⁶ , B ⁷ , and B ⁸ are independently − OR ¹ , —SR ² , —SeR ³ , —NR ⁴ · R ⁵ , —NHR ⁶ , or —R ⁷ (where R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , and R ⁷ is independently a straight-chain or branched hydrocarbon group having 1 to 12 carbon atoms). The hole transport layer material according to claim 1, wherein the compound is represented by the following general formula (2).
A substrate having a transparent conductive film,
An anti-recombination layer for transferring electrons to the transparent conductive film and preventing reverse electron transfer;
An electrolytic layer formed by adsorbing a porous semiconductor to a dye that generates electrons when excited by light,
Holes generated from the dye pass, and a hole transport layer having the hole transport layer material, and a laminate that is stacked in this order,
The hole transport layer according to claim 1, further comprising: a photoelectrode that emits the electrons through the transparent conductive film; and an electrode that includes a counter electrode provided on a surface of the hole transport layer. Solar cell using materials.