JP2017066096A - Hole transport bed material and solar cell using hole transport bed material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hole transport bed material having superior hole transportability and durability cheaply, and a solar cell having high photoelectric conversion efficiency by using the hole transport bed material.SOLUTION: A hole transport bed material is a compound which has a phthalocyanine skeleton as a central structure and a substituent is introduced into the periphery of the phthalocyanine skeleton for solubility acquisition to a solvent and improvement of electrical characteristics. A solar cell uses the hole transport bed material.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 elements such as silicon, compound semiconductors, and organic semiconductors, but in addition to high light collection capabilities, 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 blocking layer made of a dense titanium dioxide (TiO ₂ ) film, and lead iodide (PbI ₂ ) and methyl as dyes that are excited by light to generate electrons. A hybrid solar cell comprising a power generation layer formed by adsorbing ammonium iodide (CH ₃ NH ₃ I) on porous titanium dioxide (TiO ₂ ), a hole transport layer, and an electrode is shown. Yes.

This power generation 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. The 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.

  Non-Patent Document 2 discloses a solar that uses a polymerized material such as poly (triarylamine) (general name “PTAA”, hereinafter referred to as this name) as a hole transport layer material. Batteries have also been reported.

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 Jun Hong Noh et al, Chemical Management for Colorful, Efficient, and Stable Inorganic-Organic Hybrid Nanostructured Solar Cells, Nano Letter, 2013, 13 (4), p 1764-1769

  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 and PTAA used as the hole transport layer material in the hybrid solar cells of Non-Patent Document 1 and Non-Patent Document 2 are inferior in durability and lose their function in a few days if left in the atmosphere. There was a problem. The reason is that Spiro-OMeTAD and PTAA have a bulky molecular structure and 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, but the performance of the solar cell changes depending on the addition amount and mixing condition (concentration distribution) of this dopant, and exhibits the same function stably. It was difficult to let

  For example, 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 and PTAA involves complicated reaction steps and a large number of steps, and many steps are required for purification. As a result, high prices of Spiro-OMeTAD and PTAA were invited. Furthermore, in the solar cell using Spiro-OMeTAD and PTAA as the hole transport layer material, the number of processes required for the production increased and the price increased.

  Therefore, in view of the above-mentioned problems of the prior art, provision of a hole transport layer material having excellent hole transportability is required, and it is required to provide a hole transport layer material excellent in durability. Further, it has been demanded to provide a hole transport layer material at a low cost. Furthermore, it has been desired to provide solar cells with high battery performance at low cost.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have a hole transport layer material having a phthalocyanine skeleton in the molecule and a specific substituent on the outer periphery of the phthalocyanine skeleton, which has high molecular planarity, It has been found that when molecules are stacked, electrical coupling between molecules such as a π-conjugated system can be secured satisfactorily and has excellent hole transport properties. Further, the present inventors have found that the hole transport layer material has excellent properties in terms of durability. When the hole transport layer material is used in a hole transport layer such as a hybrid solar cell, the hole transport layer material exhibits excellent hole transportability, exhibits excellent battery performance in initial experiments, and is also durable. It has been found that it is excellent, and the present invention has been completed.

（一般式（Ｉ）において、
Ｍは、亜鉛（Zn）、銅（Cu）、コバルト（Co）、鉄（Fe）、ニッケル（Ni）、鉛（Pb）、マンガン（Mn）又はスズ（Sn）であり、
R^1a及びR^1bは互いに独立で、一方が下記置換基（Ａ）〜（Ｉ）から選択され、他方は水素であり、
R^2a及びR^2bは互いに独立で、一方が下記置換基（Ａ）〜（Ｉ）から選択され、他方は水素であり、
R^3a及びR^3bは互いに独立で、一方が下記置換基（Ａ）〜（Ｉ）から選択され、他方は水素であり、
R^4a及びR^4bは互いに独立で、一方が下記置換基（Ａ）〜（Ｉ）から選択され、他方は水素であり、
R^1a又はR^1bで選択される置換基、R^2a又はR^2bで選択される置換基、R^3a又はR^3bで選択される置換基、R^4a又はR^4bで選択される置換基は同一である。

ここで、前記置換基（Ａ）のX¹が、C₆〜C₈アルキル基であり、前記置換基（Ｂ）のX²が、C₆〜C₈アルキル基であり、前記置換基（Ｃ）のX³が、C₆〜C₈アルキル基であり、前記置換基（Ｄ）のX⁴が、C₆〜C₈アルキル基であり、前記置換基（Ｅ）のX⁵及びX⁶が、同一でC₆〜C₈アルキル基であり、前記置換基（Ｆ）のX⁷及びX⁸が、同一でC₄〜C₆アルキル基又はC₁〜C₃アルコキシ基であり、前記置換基（Ｇ）のX⁹が、C₄〜C₆アルキル基又はジフェニルアミノ基であり、前記置換基（Ｉ）のX¹⁰が、C₄〜C₆アルキル基である。）

（一般式（ＩＩ）、（ＩＩＩ）において、
Ｍは、亜鉛（Zn）、銅（Cu）、コバルト（Co）、鉄（Fe）、ニッケル（Ni）、鉛（Pb）、マンガン（Mn）又はスズ（Sn）であり、
R⁵、R⁶、R⁷、R⁸、R⁹、R¹⁰、R¹¹、及びR¹²は同一の置換基であり、下記の（Ｊ）〜（Ｎ）から選択される。

ここで、前記置換基（Ｊ）のX¹¹が、C₁〜C₆アルキル基であり、前記置換基（Ｋ）のX¹²が、C₄〜C₆アルキル基、C₁〜C₃アルコキシ基、又はジフェニルアミノ基であり、前記置換基（Ｌ）のX¹³及びX¹⁴が、同一でC₁〜C₃アルコキシ基であり、前記置換基（Ｍ）のX¹⁵が、C₄〜C₆アルキル基であり、前記置換基（Ｎ）のX¹⁶はC₁〜C₃アルコキシ基、又は水素である。） The characteristic structure of the hole transport layer material according to the present invention is that it is a compound selected from the following general formulas (I) to (III).

(In general formula (I),
M is zinc (Zn), copper (Cu), cobalt (Co), iron (Fe), nickel (Ni), lead (Pb), manganese (Mn) or tin (Sn);
R ^1a and R ^1b are independent of each other, one is selected from the following substituents (A) to (I), the other is hydrogen,
R ^2a and R ^2b are independent of each other, one is selected from the following substituents (A) to (I), the other is hydrogen,
R ^3a and R ^3b are independent of each other, one is selected from the following substituents (A) to (I), the other is hydrogen,
R ^4a and R ^4b are independent of each other, one is selected from the following substituents (A) to (I), the other is hydrogen,
The substituent selected by R ^1a or R ^1b , the substituent selected by R ^2a or R ^2b , the substituent selected by R ^3a or R ^3b , and the substituent selected by R ^4a or R ^4b are the same. is there.

Here, X ¹ of the substituent (A) is a C ₆ -C ₈ alkyl group, X ² of the substituent (B) is a C ₆ -C ₈ alkyl group, and the substituent (C X ³ is a C ₆ -C ₈ alkyl group, X ⁴ of the substituent (D) is a C ₆ -C ₈ alkyl group, and X ⁵ and X ⁶ of the substituent (E) are , The same C ₆ -C ₈ alkyl group, and X ⁷ and X ⁸ of the substituent (F) are the same C ₄ -C ₆ alkyl group or C ₁ -C ₃ alkoxy group, and the substituent X ^{9 in} (G) is a C _{4 to} C ₆ alkyl group or a diphenylamino group, and X ^{10 in the} substituent (I) is a C _{4 to} C ₆ alkyl group. )

(In the general formulas (II) and (III),
M is zinc (Zn), copper (Cu), cobalt (Co), iron (Fe), nickel (Ni), lead (Pb), manganese (Mn) or tin (Sn);
R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² are the same substituent and are selected from the following (J) to (N).

Here, X ¹¹ of the substituent (J) is a C _{1 to} C ₆ alkyl group, and X ¹² of the substituent (K) is a C _{4 to} C ₆ alkyl group or a C _{1 to} C ₃ alkoxy group. Or X ¹³ and X ¹⁴ of the substituent (L) are the same C ₁ -C ₃ alkoxy group, and X ^{15 of the} substituent (M) is C ₄ -C _6. An alkyl group, and X ¹⁶ of the substituent (N) is a C ₁ -C ₃ alkoxy group or hydrogen. )

  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. Specifically, the phthalocyanine that forms the skeleton of the hole transport layer material of this configuration is a cyclic structure having high planarity, and forms a cyclic π electron cloud. The π-electron clouds overlap between phthalocyanine molecules, and the phthalocyanine molecules are stabilized in an arrangement (called “π-π stacking”) in which multiple flat plates are stacked. Thereby, phthalocyanine can move a hole to the direction which piled the flat plate, and can exhibit favorable hole transportability.

  Moreover, the hole transport layer material of this configuration has excellent characteristics in terms of long-term durability. The aforementioned π-π stacking state in phthalocyanine is very stable and strong, and oxidation (electron emission) and reduction (electron injection) from the outside are caused by diffusion of the attack to multiple molecules. Can maintain a stable state and has high weather resistance. Since the hole transport layer material of this configuration has a phthalocyanine skeleton having such weather resistance, it has a characteristic of high durability without being decomposed by light irradiation or temperature and humidity.

  In addition, since the hole transport layer material of this configuration has high flatness as described above, voids do not occur between molecules, and other molecules that can cause a decrease in hole transport properties are mixed between molecules. Can be prevented. Moreover, electrical coupling between molecules can be ensured. Thereby, the hole transport performance is stable, and excellent performance can be exhibited in terms of durability.

  The hole transport layer material of this configuration has excellent characteristics in terms of solubility in a solvent. Phthalocyanine has extremely low solubility in solvents due to the strong interaction between molecules due to the aforementioned π-π stacking, and its use has been limited. However, the hole transport layer material of this configuration is bulky to the outer periphery of the phthalocyanine skeleton so as not to prevent π-π stacking, and substituents are uniformly introduced to improve solubility in a solvent. Thereby, the hole transport layer material of this configuration becomes soluble in a solvent such as chlorobenzene, and can be used in place of a compound having a spiro ring structure such as general-purpose Spiro-OMeTAD.

  The hole transport layer material of this configuration can control electrical characteristics and solubility in a solvent by changing a substituent or a central metal introduced into the outer periphery of the phthalocyanine skeleton. Thereby, the hole transport layer material which has further high performance can be provided.

  The hole transport layer material of this configuration can be synthesized easily and inexpensively. The hole transport layer material with this configuration can be synthesized in fewer steps and is easier to purify compared to conventional Spiro-OMeTAD and other compounds with a spiro ring structure, reducing the cost required for synthesis. can do.

  Since the hole transport layer material of this configuration has excellent characteristics as described above, it can be suitably used as the hole transport layer material of the solar cell 10.

Another feature of the present invention is a compound represented by the general formula (I),
The substituent (A) is a 5-hexyl-thiophen-2-yl group or a 5- (2-ethylhexyl) -thiophen-2-yl group;
The substituent (B) is a 5- (hexylsulfanyl) -thiophen-2-yl group;
The substituent (C) is a 5′-hexyl-2,2′-bithiophen-5-yl group or a 5 ′-(2-ethylhexyl) -2,2′-bithiophen-5-yl group;
The substituent (D) is a 5-hexyl-thieno [3,2-b] thiophen-2-yl group or a 5- (2-ethylhexyl) -thieno [3,2-b] thiophen-2-yl group. And
The substituent (E) is a 5,5 ″ -dihexyl-2,2 ′: 3 ′, 2 ″ -terthiophene-5′-yl group;
The substituent (F) is a bis (4-hexylphenyl) amino group, a bis (4-methoxyphenyl) amino group, or a bis (4-tert-butylphenyl) amino group;
The substituent (G) is a 4-tert-butylphenyl group or a 4- (diphenylamino) phenyl group;
The substituent (H) is a 2,6-diphenylphenoxy group;
The point is that the substituent (I) is a tert-butyl group.

  According to this configuration, each of the four imidazole ring benzene ring portions located on the outer periphery of the phthalocyanine skeleton has one bulk at the β-position so as not to prevent intermolecular π-π stacking, and to the solvent. A hole transport layer material can be provided as a phthalocyanine derivative having a suitable substituent introduced to improve solubility. Thereby, it is possible to particularly suitably control the electrical characteristics and the solubility in a solvent, and it is possible to provide a hole transport layer material having high performance.

Another characteristic feature is that in the compound represented by the general formula (II),
The substituent (J) is a methoxy group, an ethoxy group, an isopropoxy group, a tert-butoxy group, or a hexyloxy group;
The substituent (K) is a 4-methoxyphenyl group, a 4-tert-butylphenyl group, or a 4- (diphenylamino) phenyl group;
The substituent (L) is a 3,4-dimethoxyphenyl group;
The substituent (M) is a (4-tert-butylphenyl) sulfanyl group;
The substituent (N) is 2,6-diphenylphenoxy group or 5-methoxy-2,6-diphenylphenoxy group.

  According to this configuration, the benzene ring part of the four imidazole rings located on the outer periphery of the phthalocyanine skeleton is bulky to two positions at the β positions so as not to prevent π-π stacking between molecules and is soluble in a solvent. A hole transport layer material can be provided as a phthalocyanine derivative into which a particularly preferable substituent has been introduced in order to improve the thickness. Thereby, it is possible to particularly suitably control the electrical characteristics and the solubility in a solvent, and it is possible to provide a hole transport layer material having high performance.

Another characteristic feature is that in the compound represented by the general formula (III),
The substituent (J) is a methoxy group, an ethoxy group, an isopropoxy group, a tert-butoxy group, or a hexyloxy group;
The substituent (K) is a 4-methoxyphenyl group, a 4-tert-butylphenyl group, or a 4- (diphenylamino) phenyl group;
The substituent (L) is a 3,4-dimethoxyphenyl group;
The substituent (M) is a (4-tert-butylphenyl) sulfanyl group;
The substituent (N) is a 5-methoxy-2,6-diphenylphenoxy group.

  According to this configuration, according to this configuration, two α-positions of the benzene ring portion of the four imidazole rings located on the outer periphery of the phthalocyanine skeleton are made so bulky as not to hinder intermolecular π-π stacking. In addition, a hole transport layer material can be provided as a phthalocyanine derivative into which a particularly preferable substituent is introduced in order to improve solubility in a solvent. Thereby, it is possible to particularly suitably control the electrical characteristics and the solubility in a solvent, and it is possible to provide a hole transport layer material having high performance.

Another structure is a point which is a compound shown by the following general formula (IV).

  According to this configuration, as a substituent, a hole transport layer as a phthalocyanine derivative in which a hexylthiophene ring is uniformly introduced as a substituent at each of the β positions of the benzene ring portions of the four imidazole rings located on the outer periphery of the phthalocyanine skeleton. Material can be provided. The substituent is bulky to the extent that it does not prevent π-π stacking between molecules of the hole transport layer material, and is particularly suitable for improving solubility in a solvent. The hole transport layer material having high performance can be provided.

  The characteristic configuration of the solar cell according to the present invention includes a substrate having a transparent conductive film, a blocking layer that transfers electrons to the transparent conductive film and prevents reverse electron transfer, and a dye that generates electrons when excited by light. A power generation layer formed by adsorption on a porous semiconductor, a hole transport layer having a hole transport layer material through which holes generated from the dye pass, and a laminated body in that order, and the transparent conductive film It is in the point provided with the photoelectrode which discharge | releases an electron, and the electrode comprised by the counter electrode provided in the surface of the said 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. In particular, since the perovskite dye crystals, which are likely to deteriorate in performance due to moisture absorption, are coated with a weather-resistant hole transport layer material, further long-term durability can be expected. Thus, the cell performance of the solar cell can be improved by the hole transport layer having the hole transport layer material having excellent characteristics. Further, by using a hole transport layer material that can be synthesized at low cost, it is possible to reduce the price of the solar cell itself.

It is a schematic cross section of a hybrid type solar cell. It is a schematic diagram from the upper side of a hybrid type solar cell. It is power generation explanatory drawing of a hybrid type solar cell. It is explanatory drawing which shows the preparation procedures 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 a figure which shows the suitable example of hole transport layer material. It is a figure which shows the synthetic scheme of hole transport layer material. The performance curve of a solar cell using Sym-HT-PcH as the hole transport layer material is shown. The performance curve of the solar cell using Spiro-OMeTAD as a hole transport layer material is shown (comparative example). It is a graph which shows the result of having compared the durability of the photovoltaic cell in the case of Sym-HT-PcH and Spiro-OMeTAD as a hole transport layer material.

  EMBODIMENT OF THE INVENTION Below, embodiment of the hybrid type solar cell 10 (an example of a solar cell. Hereafter, it describes as "the solar cell 10.") using the hole transport layer material which concerns on embodiment of this invention is described based on drawing. To do. The solar cell 10 is configured to include a perovskite dye produced from an organic and inorganic hybrid compound. 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 of solar cell according to this embodiment)
As shown in FIGS. 1 and 2, the solar cell 10 according to the present embodiment is provided on the substrate 2 having the transparent substrate 21 and the transparent conductive film 22, and passes electrons to the transparent conductive film 22. In addition, the hole transport layer 5 and the transparent conductive film 22 are separated to prevent recombination (reverse electron transfer) between electrons and holes. The blocking layer 3 is provided on the blocking layer 3 and excited by light to emit electrons. A laminate 11 composed of a power generation layer 4 formed by adsorbing the generated dye 44 to the porous semiconductor 41 and a hole transport layer 5 provided on the power generation layer 4 and through which holes generated in the dye 44 pass. I have. An electrode 6 is provided on the surface of the blocking layer 3 and includes 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. It has. 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). .

For the blocking layer 3 and the porous semiconductor 41, metal oxides are suitable, for example, titanium dioxide (TiO ₂ ), zinc oxide (ZnO), niobium oxide (Nb ₂ O ₅ ), tin dioxide (SnO ₂ ), and oxidation. Aluminum (Al ₂ O ₃ ) or the like is used. In particular, it is preferably configured as a sintered body of titanium dioxide (TiO ₂ ) that can secure a large surface area for adsorbing the dye 44. In addition, the blocking layer 3 is partly extended to the transparent conductive film 22, and the transparent conductive film 22 is partitioned. Furthermore, the blocking layer 3 is formed with a dense insulating layer 31 so that electrons can pass in the stacking direction but are difficult to move in the lateral direction. That is, electrons that have entered from the blocking layer 3 smoothly move in the laminating direction of the transparent conductive film 22 and are supplied to the photoelectrode 61 and are not short-circuited because the insulating layer 31 prevents movement to the counter electrode 62. .

The dye 44 is formed by reacting a compound composed of lead and a halogen element X (PbX ₂ , X = halogen element) and methylammonium iodide (CH ₃ NH ₃ I: hereinafter referred to as MAI). Is done. Specifically, after a solution 42 containing lead and a halogen element X is infiltrated and dried inside the pores of the porous semiconductor 41, it is immersed in a mixed solution 43 of MAI, and a perovskite dye (X = I In this case, crystals of CH ₃ NH ₃ PbI ₃ ) are rapidly formed. Note that iodine, bromine, chlorine, or the like can be used as the halogen element X, 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 blocking layer 3, and most of the light reaches the power generation layer 4. When the incident light reaching the power generation 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 blocking 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.

(Procedure for manufacturing solar cell according to this embodiment)
The manufacturing procedure of the solar cell 10 according to the present embodiment will be described with reference to FIG. 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.

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 partially remove the transparent conductive film 22 to form a recess 221 into which the insulating layer 31 is inserted, followed by cleaning. Next, the blocking layer 3 is formed on the entire surface of the substrate 2 by an ALD method (atomic layer deposition method), an SPD method (spray pyrolysis method), or the like. The blocking layer is preferably formed as a dense TiO ₂ layer. 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 blocking layer 3. Preferably formed as a porous layer of _{TiO 2 (p-TiO 2)} . The porous semiconductor 41 is prepared by diluting the nanoparticle paste with a solvent, applying and drying the spin paste method at a rotational speed of, for example, 4000 rpm to 6000 rpm, removing the masking, and heating at 450 ° C. to 550 ° C. for sintering. It is formed.

For example, an N, N-dimethylformamide solution 42 of lead iodide (PbI ₂ ) is prepared, dropped on the porous semiconductor 41, and then subjected to pores (p-TiO ₂₎ by spin coating at a rotational speed of 5000 rpm to 8000 rpm, for example. ) Penetration inside and removal of excess solution. The PbI ₂ layer is formed by drying at 60 ° C. to 120 ° C. (preferably 70 ° C. to 90 ° C.).

Porous semiconductor in which Methylammonium Iodide (CH ₃ NH ₃ I, sometimes referred to as “MAI”) isopropyl alcohol solution 43 (2 to 20 mg / ml) is impregnated with substrate 2, blocking layer 3 and lead iodide 41 is immersed at 0 ° C. to 80 ° C. (preferably normal temperature) (MAI dipping method). PbI ₂ and MAI react to form a dye 44 [(CH ₃ NH ₃ ) PbI ₃ ] as a perovskite layer inside and above the pores of the porous semiconductor 41, and then irrigated with a pure isopropyl alcohol solution to 60 ° C. to 120 ° C. (Preferably 70 ° C to 100 ° C).

The hole transport layer material according to the present embodiment is prepared, for example, as a chlorobenzene solution 60 to 90 mg / ml (including some additives). This is dropped, an excess solution is removed by spin coating, and the hole transport layer 5 is formed by drying. The steps from the formation of the PbI ₂ layer to the formation of the hole transport layer 5 are preferably performed in a dry nitrogen atmosphere such as a glove box. Finally, a thin film such as gold is attached to the surfaces of the blocking layer 3 and the hole transport layer 5 by a vacuum vapor deposition method or the like to form the electrode 6.

In the above preparation procedure, the perovskite dye as the dye 44 is controlled in crystal growth by two steps, but this may be performed in one step. For example, a perovskite ((CH ₃ NH ₃ ) PbI ₃ ) solution is permeated into the pores of the porous semiconductor 41 by spin coating. Toluene is dropped into the spin to precipitate microcrystals and mirror the surface (negative solvent precipitation method). Subsequently, the hole transport layer 5 may be formed of the hole transport layer material according to the present embodiment.

(Hole transport layer material according to this embodiment)
The hole transport layer material according to the present embodiment has a phthalocyanine skeleton as a central structure. Phthalocyanine is a huge cyclic structure in which four isoindoles are bridged through nitrogen atoms, and forms metal phthalocyanine coordinated around a metal element. In the hole transport layer material according to this embodiment, a substituent is introduced to the outer periphery of the phthalocyanine skeleton in order to obtain solubility in a solvent and improve electrical characteristics. The substituents are preferably introduced evenly around the outer periphery of the phthalocyanine skeleton, and are particularly preferably constructed as a symmetrical type.

  The characteristic configuration of the hole transport layer material according to this embodiment is a compound selected from the following general formulas (I) to (II). The compound represented by the general formula (I) has a structure in which a substituent is evenly introduced at one position at the β-position of each benzene ring portion in the four indole rings constituting the phthalocyanine skeleton. That is, a substituent is introduced into one of 2-position or 3-position, one of 9-position or 10-position, one of 16-position or 17-position, one of 23-position or 24-position of the phthalocyanine ring. The compound represented by the general formula (II) has a structure in which substituents are evenly introduced at two positions of the β-position of each benzene ring portion in the four indole rings, and the 2-position, 3-position, 9 of the phthalocyanine ring. Substituents are introduced at positions 10, 10, 16, 17, 23 and 24. The general formula (III) has a structure in which substituents are evenly introduced at two positions on the α-position, and the 1-position, 4-position, 8-position, 11-position, 15-position, 18-position, 22-position and 25-position of the phthalocyanine ring. A substituent is introduced at the position. 5 to 7 show representative examples of the hole transport layer material according to the present embodiment. However, the present invention is not limited to this.

  The hole transport layer material according to this embodiment is configured as a metal phthalocyanine complex in which a metal element is coordinated at the center. Therefore, in the general formulas (I) to (III), M is a metal atom, a metal oxide or a metal halide, and preferably zinc (Zn), copper (Cu), cobalt (Co), iron (Fe ), Nickel (Ni), lead (Pb), manganese (Mn) or tin (Sn). Particularly preferred is zinc.

  In the hole transport layer material according to this embodiment, a substituent is introduced to the outer periphery of the phthalocyanine skeleton in order to obtain solubility in a solvent and improve electrical characteristics. Suitable substituents are shown below.

（ここで、前記置換基（Ａ）のX¹が、C₆〜C₈アルキル基であり、前記置換基（Ｂ）のX²が、C₆〜C₈アルキル基であり、前記置換基（Ｃ）のX³が、C₆〜C₈アルキル基であり、前記置換基（Ｄ）のX⁴が、C₆〜C₈アルキル基であり、前記置換基（Ｅ）のX⁵及びX⁶が、同一でC₆〜C₈アルキル基であり、前記置換基（Ｆ）のX⁷及びX⁸が、同一でC₄〜C₆アルキル基又はC₁〜C₃アルコキシ基であり、前記置換基（Ｇ）のX⁹が、C₄〜C₆アルキル基又はジフェニルアミノ基であり、前記置換基（Ｉ）のX¹⁰が、C₄〜C₆アルキル基である。） In general formula (I):
R ^1a and R ^1b are independent of each other, one is selected from the following substituents (A) to (I), the other is hydrogen,
R ^2a and R ^2b are independent of each other, one is selected from the following substituents (A) to (I), the other is hydrogen,
R ^3a and R ^3b are independent of each other, one is selected from the following substituents (A) to (I), the other is hydrogen,
R ^4a and R ^4b are independent of each other, one is selected from the following substituents (A) to (I), the other is hydrogen,
The substituent selected by R ^1a or R ^1b , the substituent selected by R ^2a or R ^2b , the substituent selected by R ^3a or R ^3b , and the substituent selected by R ^4a or R ^4b are the same. is there.

(Here, X ¹ of the substituent (A) is a C ₆ -C ₈ alkyl group, X ² of the substituent (B) is a C ₆ -C ₈ alkyl group, and the substituent ( X ^{3 in} C) is a C ₆ -C ₈ alkyl group, X ^{4 in the} substituent (D) is a C ₆ -C ₈ alkyl group, and X ⁵ and X ^{6 in the} substituent (E) Are the same C ₆ -C ₈ alkyl group, and X ⁷ and X ⁸ of the substituent (F) are the same C ₄ -C ₆ alkyl group or C ₁ -C ₃ alkoxy group, X ^{9 of the} group (G) is a C _{4 to} C ₆ alkyl group or a diphenylamino group, and X ¹⁰ of the substituent (I) is a C _{4 to} C ₆ alkyl group.)

The C ₆ -C ₈ alkyl group in the substituent (A) may be linear or branched. Particularly preferred is a hexyl group or a 2-ethylhexyl group. The alkyl chain of the C ₆ -C ₈ alkylsphenyl group in the substituent (B) may be linear or branched. Preferably, it is a hexyl chain. The C ₆ -C ₈ alkyl group in the substituent (C) may be linear or branched. Preferably, it is a hexyl group or 2-ethylhexyl group. The C ₆ -C ₈ alkyl group in the substituent (D) may be linear or branched. Preferably, it is a hexyl group or 2-ethylhexyl group. The C ₆ -C ₈ alkyl group in the substituent (E) may be linear or branched. Preferably, it is a hexyl group. The C _{4 to} C ₆ alkyl group in the substituent (F) may be linear or branched. Preferably, it is a hexyl group or a t-butyl group. Further, the alkyl chain of the C ₁ -C ₃ alkoxy group may be linear or branched. Preferably, it is a methyl chain. The C _{4 to} C ₆ alkyl group in the substituent (G) may be linear or branched. Preferably, it is a t-butyl group. The C _{4 to} C ₆ alkyl group in the substituent (G) may be linear or branched. Preferably, it is a t-butyl group.

Here, the C ₁ -C ₃ alkyl group is an alkyl group having ₁ to ₃ carbon atoms, specifically, a methyl group, an ethyl group, a propyl group, or an isopropyl group. C ₄ -C ₆ alkyl group is an alkyl group having ₄ to ₆ carbon atoms, specifically, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group, Isopentyl group, neopentyl group, t-pentyl group, s-pentyl group, 2-methylbutyl group, 1-ethylpropyl group, 2-ethylpropyl group, n-hexyl group, isohexyl group, neohexyl group, t-hexyl group, Examples include 2,2-dimethylbutyl group, 2-methylpentyl group, 3-methylpentyl group, 1-ethylbutyl group, 2-ethylbutyl group, 1-propylpropyl group and the like. C ₆ -C ₈ alkyl group is an alkyl group having ₆ to ₈ carbon atoms, n-hexyl group, isohexyl group, neohexyl group, t-hexyl group, 2,2-dimethylbutyl group, 2-methylpentyl Group, 3-methylpentyl group, 1-ethylbutyl group, 2-ethylbutyl group, 1-propylpropyl group, n-heptyl group, isoheptyl group, s-heptyl group, t-heptyl group, 2,2-dimethylpentyl group, 3,3-dimethylpentyl group, 1-methylhexyl group, 2-methylhexyl group, 3-methylhexyl group, 4-methylhexyl group, 1-ethylpentyl group, 2-ethylpentyl group, 3-ethylpentyl group, 1-propylbutyl group, 2-propylbutyl group, n-octyl group, isooctyl group, t-octyl group, neooctyl group, 2,2-dimethylhexyl group, 3,3-dimethylhexyl group, 4,4-dimethylhexyl Group, 1-methylheptyl group, 2-methylheptyl group 3-methylheptyl group, 4-methylheptyl group, 5-methylheptyl group, 1-ethylhexyl group, 2-ethylhexyl group, 3-ethylhexyl group, 4-ethylhexyl group, 1-propylpentyl group, 2-propylpentyl group And 3-propylpentyl group. The C ₁ -C ₆ alkyl group is an alkyl group having 1 to 6 carbon atoms, and specific alkyl groups are as described above. “N” is an abbreviation for “normal”, “s” is an abbreviation for “sec” and “secondery”, and “t” is an abbreviation for “tert” and “tertiary”. The same applies to the alkyl chain.

Preferably, in general formula (I), but not limited thereto,
The substituent (A) is a 5-hexyl-thiophen-2-yl group or a 5- (2-ethylhexyl) -thiophen-2-yl group;
The substituent (B) is a 5- (hexylsulfanyl) -thiophen-2-yl group;
The substituent (C) is a 5′-hexyl-2,2′-bithiophen-5-yl group or a 5 ′-(2-ethylhexyl) -2,2′-bithiophen-5-yl group;
The substituent (D) is a 5-hexyl-thieno [3,2-b] thiophen-2-yl group or a 5- (2-ethylhexyl) -thieno [3,2-b] thiophen-2-yl group. And
The substituent (E) is a 5,5 ″ -dihexyl-2,2 ′: 3 ′, 2 ″ -terthiophene-5′-yl group;
The substituent (F) is a bis (4-hexylphenyl) amino group, a bis (4-methoxyphenyl) amino group, or a bis (4-tert-butylphenyl) amino group;
The substituent (G) is a 4-tert-butylphenyl group or a 4- (diphenylamino) phenyl group;
The substituent (H) is a 2,6-diphenylphenoxy group;
The substituent (I) is a tert-butyl group.

ここで、置換基（Ｊ）のX¹¹が、C₁〜C₆アルキル基であり、置換基（Ｋ）のX¹²が、C₄〜C₆アルキル基、C₁〜C₃アルコキシ基、又はジフェニルアミノ基であり、置換基（Ｌ）のX¹³及びX¹⁴が、同一でC₁〜C₃アルコキシ基であり、置換基（Ｍ）のX¹⁵が、C₄〜C₆アルキル基であり、置換基（Ｎ）のX¹⁶が、C₁〜C₃アルコキシ基、又は水素である。） In general formulas (II) and (III),
R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² are the same substituent and are selected from the following (J) to (N).

Here, X ¹¹ of the substituent (J) is a C _{1 to} C ₆ alkyl group, and X ¹² of the substituent (K) is a C _{4 to} C ₆ alkyl group, a C _{1 to} C ₃ alkoxy group, or It is a diphenylamino group, X ¹³ and X ¹⁴ of the substituent (L) are the same C ₁ -C ₃ alkoxy group, and X ¹⁵ of the substituent (M) is a C ₄ -C ₆ alkyl group X ^{16 of} the substituent (N) is a C ₁ -C ₃ alkoxy group or hydrogen. )

The C ₁ -C ₆ alkyl group in the substituent (J) may be linear or branched. A methyl group, an ethyl group, an isopropyl group, a tert-butyl group, or a hexyl group is preferable. The C _{4 to} C ₆ alkyl group in the substituent (K) may be linear or branched. A tert-butyl group is preferable. The alkyl chain of the C ₁ -C ₃ alkoxy group may be linear or branched. Preferably, it is a methyl chain. The alkyl chain of the C ₁ -C ₃ alkoxy group in the substituent (L) may be linear or branched. Preferably, it is a methyl chain. The C _{4 to} C ₆ alkyl group in the substituent (M) may be linear or branched. A tert-butyl group is preferable. Alkyl chains of C ₁ -C ₃ alkoxy group in the substituent (N) may be either a separate linear and branched. Preferably, it is a methyl chain.

Preferably, in the compound represented by the general formula (II), but not limited thereto,
The substituent (J) is a methoxy group, an ethoxy group, an isopropoxy group, a tert-butoxy group, or a hexyloxy group;
The substituent (K) is a 4-methoxyphenyl group, a 4-tert-butylphenyl group, or a 4- (diphenylamino) phenyl group;
The substituent (L) is a 3,4-dimethoxyphenyl group;
The substituent (M) is a (4-tert-butylphenyl) sulfanyl group;
The substituent (N) is a 2,6-diphenylphenoxy group or a 5-methoxy-2,6-diphenylphenoxy group.

Preferably, the compound represented by the general formula (III) is not limited thereto,
The substituent (J) is a methoxy group, an ethoxy group, an isopropoxy group, a tert-butoxy group, or a hexyloxy group;
The substituent (K) is a 4-methoxyphenyl group, a 4-tert-butylphenyl group, or a 4- (diphenylamino) phenyl group;
The substituent (L) is a 3,4-dimethoxyphenyl group;
The substituent (M) is a (4-tert-butylphenyl) sulfanyl group;
The substituent (N) is a 5-methoxy-2,6-diphenylphenoxy group.

（一般式（Ｖ）において、
R^13a及びR^13bは互いに独立で、一方が下記置換基（Ｏ）であり、他方は水素であり、
R^14a及びR^14bは互いに独立で、一方が下記置換基（Ｏ）であり、他方は水素であり、
R^15a及びR^15bは互いに独立で、一方が下記置換基（Ｏ）であり、他方は水素であり、
R^16a及びR^16bは互いに独立で、一方が下記置換基（Ｏ）であり、他方は水素である。

[Preferred example of hole transport layer material according to this embodiment]
A preferred example of the hole transport layer material according to this embodiment is shown below as general formula (V). In the specification, the hole transport layer material may be referred to as “Sym-HT-PcH”. In the compound represented by the general formula (IV), zinc is coordinated as a central metal, and a hexylthiophene ring is introduced as a substituent at each β-position of the benzene ring portion of the four indole rings that form the outer peripheral skeleton of the phthalocyanine ring. Configured. That is, a hexylthiophene ring is introduced into one of the 2-position or 3-position, one of 9-position or 10-position, one of 16-position or 17-position, one of 23-position or 24-position of the phthalocyanine ring.

(In general formula (V),
R ^13a and R ^13b are mutually independent, one is the following substituent (O), the other is hydrogen,
R ^14a and R ^14b are independent of each other, one is the following substituent (O), the other is hydrogen,
R ^15a and R ^15b are independent of each other, one is the following substituent (O), the other is hydrogen,
R ^16a and R ^16b are independent of each other, one is the following substituent (O) and the other is hydrogen.

Of the compounds represented by the general formula (V), compounds represented by the following general formula (IV) are particularly preferred and exemplified.

[Method of synthesizing hole transport layer material according to this embodiment]
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 method of Sym-HT-PcH, which is a preferred example of the hole transport layer material, and is not limited to this, and may be synthesized using other methods as appropriate. Can do.

  The phthalocyanine skeleton of the hole transport layer material according to this embodiment can be formed by a cyclization reaction of phthalonitrile by heating with phthalonitrile and a metal salt coordinated as a central metal. As for the introduction of the substituent, the hole transport layer material according to the present embodiment in which the substituent is introduced symmetrically can be easily synthesized by introducing a desired substituent into phthalonitrile in advance.

  In the synthesis, a hole transport layer material having various substituents can be provided by appropriately changing the type of substituent introduced into phthalonitrile. Moreover, the hole transport layer material which has various center metals can be provided by changing suitably the kind of metal salt used for cyclization reaction. Thereby, the electrical characteristics of the hole transport layer material can be controlled, and a hole transport layer material having higher performance can be constructed. Therefore, it can be expected that a compound having a further improved hole transport property or a compound which does not require any addition of a dopant as a hole transport layer material.

[Characteristics of hole transport layer material according to this embodiment]
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. The phthalocyanine constituting the skeleton of the hole transport layer material according to the present embodiment is a condensed polyaromatic compound in which four isoindoles are cross-linked through nitrogen atoms. It is an annular structure with high planarity, and forms an annular continuous π electron cloud. This π-electron cloud overlaps between phthalocyanine molecules and stabilizes in an arrangement (called “π-π stacking”) in which multiple flat plates are stacked. The holes can be moved in the direction in which the flat plates are stacked, and good hole transportability can be exhibited.

  The hole transport layer material according to the present embodiment has excellent characteristics in terms of long-term durability. Phthalocyanines have been used in pigments and paints and labels because they are not only vivid in color, but also very chemically and physically stable and weather resistant. The aforementioned π-π stacking state in phthalocyanine is very stable and strong, and oxidation (electron emission) and reduction (electron injection) from the outside are caused by diffusion of the attack to multiple molecules. Can maintain a stable state and has high weather resistance. Since the hole transport layer material according to the present embodiment has a phthalocyanine skeleton having such weather resistance, it has a characteristic of high durability without being decomposed by light irradiation or temperature and humidity.

  In addition, when the conventional Spiro-OMeTAD was laminated as a hole transport layer or the like and fixed on the substrate, there was a problem that a gap was generated between molecules due to its molecular structure, and other molecules were mixed. 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, since the hole transport layer material according to the present embodiment has high planarity as described above, voids are not generated between molecules, electrical coupling between molecules can be ensured, and hole transport properties are reduced. It is possible to prevent problems such as mixing of other molecules that can be a cause of the contamination between molecules. Thereby, the hole transport performance is stable, and excellent performance can be exhibited in terms of durability.

  The hole transport layer material according to this embodiment has excellent properties in terms of solubility in a solvent. Since phthalocyanine interacts strongly with each other due to the aforementioned π-π stacking, its solubility in not only water but also an organic solvent is extremely low, and its use is limited. In the hole transport layer material according to the present embodiment, the substituents were uniformly introduced on the outer periphery of the phthalocyanine skeleton so as not to hinder π-π stacking and to improve the solubility in a solvent. Thereby, the hole transport layer material according to the present embodiment becomes soluble in a solvent such as chlorobenzene, and the hole transport layer 5 of the hybrid solar cell 10 can be formed by a coating method such as spin coating. It can be used in place of a compound having a spiro ring structure such as Spiro-OMeTAD that has been widely used as the hole transport layer 5 of the solar cell 10 in the past, and the production procedure can be similarly performed.

  In addition, the hole transport layer material according to the present embodiment controls electrical properties including hole transportability and solubility in a solvent by changing a substituent or a central metal introduced into the outer periphery of the phthalocyanine skeleton. be able to. Thereby, it is possible to provide a hole transport layer material having higher performance. It is possible to more appropriately control the electrical coupling between the molecules, and it can be expected to provide a compound with further improved hole transport properties and a compound that does not require any addition of a dopant.

  The hole transport layer material according to the present embodiment can be synthesized easily and inexpensively. The phthalocyanine skeleton can be formed by a cyclization reaction of phthalonitrile by heating with phthalonitrile and a metal salt coordinated as a central metal. As for the introduction of substituents, it is very simple to introduce a substituent into phthalocyanine symmetrically by introducing a desired substituent into phthalonitrile in advance. It can be provided at low cost. Thus, the hole transport layer material according to the present embodiment can be synthesized with fewer steps as compared with a compound having a spiro ring structure such as a conventional Spiro-OMeTAD, and is easily purified. The cost required for synthesis can be reduced.

  Since the hole transport layer material according to the present embodiment has excellent characteristics as described above, it can be suitably used as the hole transport layer material of the solar cell 10.

[Characteristics of Solar Cell 10 According to this Embodiment]
The solar cell 10 according to the present embodiment includes the hole transport layer 5 formed using the hole transport layer material of the present invention having excellent characteristics as described above. Specifically, since the hole transport layer material according to the present embodiment has excellent hole transportability capable of capturing and moving holes excellently and stably, the solar cell 10 of the present invention. By using this as the hole transport layer 5, the photoelectric conversion efficiency is improved, and the battery performance is improved.

  Moreover, since the composition of the hole transport layer material of the present embodiment is stable, it can be expected that the same performance is always obtained. When using the conventional Spiro-OMeTAD with a hole transport layer material, it was necessary to add a dopant having a function of improving the hole transport efficiency. On the other hand, there is a possibility that the hole transport layer material of this embodiment can achieve good hole transport properties without adding a dopant.

  Since the hole transport layer material according to the present embodiment is excellent in durability, the solar cell 10 according to the present embodiment is used as the hole transport layer 5 so that the solar cell 10 has a long-term durability. Can be improved. Furthermore, in the conventional perovskite solar cell using Spiro-OMeTAD as the hole transport layer material, performance degradation of the perovskite crystal due to moisture absorption has been a problem, but the perovskite crystal is related to this embodiment having weather resistance. It will be coat | covered with hole transport layer material, and the long-term durability of the said solar cell can be improved also from this side surface.

  The hole transport layer 5 formed of the hole transport layer material according to the present embodiment having such excellent characteristics can improve the battery performance of the solar cell 10 according to the present embodiment.

  Further, as described above, since the hole transport layer material according to the present embodiment can be synthesized at a low cost with a small number of steps, the price of the solar cell 10 itself according to the present embodiment using the hole transport layer 5 as the hole transport layer 5 is reduced. Can be achieved.

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

  The invention is illustrated in detail by the following examples. In the following examples, “Sym-HT-PcH” is exemplified as the hole transport layer material, but the present invention is not limited to this.

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

  In this example, the synthesized hole transport layer material is called “Sym-HT-PcH” shown in the general formula (IV). A synthesis scheme will be described with reference to FIG.

Synthesis of Sym-HT-PcH (Step 1) Synthesis of 4-iodophthalonitrile (compound 2) Sulfuric acid (H ₂ SO ₄ , 12 mL) and water (6 mL) are mixed, and 4- Aminophthalonitrile (Compound 1: 2.5 g, 17.48 mmol) was added and stirred and cooled to -10 ° C. To this reaction mixture, sodium nitrite (NaNO ₂ : 1.206 g, 17.487 mmol) dissolved in water was added dropwise with stirring while maintaining the reaction mixture temperature at −10 to 0 ° C. After completion of the dropping, the reaction mixture was quickly filtered using a suction filtration device, and the filtrate was separated. Sodium iodide (7.9 g, 47 mmol) was dissolved in 20 ml of water, and the previously prepared filtrate was added dropwise to the cooled one, and stirring was continued while maintaining at 0 ° C. When the temperature of the mixed liquid changed to black was raised to room temperature while stirring, black precipitates appeared, and the solid was collected by filtration. This solid was dissolved in dichloromethane (CH ₂ Cl ₂ : 50 mL), washed twice with 50 ml of cold water, washed with 50 ml of 10% sodium hydrogen carbonate (NaHCO ₃ ) solution, once again with 50 ml of cold water, and saturated sodium sulfite. Washed once with 50 ml of (Na ₂ S ₂ O ₃ ) aqueous solution and finally three times with 50 ml of water. The washed solution was dried over magnesium sulfate (MgSO ₄ ), and then the solvent was distilled off until the total amount was about 10 ml. Purification by chromatography using a silica gel column gave the desired 4-iodophthalonitrile (compound 2) white solid in 70% yield.

(Step 2) Synthesis of 4- (5-hexylthiophen-2-yl) phthalonitrile (4- (5-hexylthiophen-2-yl) phthalonitrile: Compound 4) 4-Iodinated phthalonitrile synthesized in Step 1 above (Compound 2: 2.5 g, 9.84 mmol) and 2- (5-hexylthiophen-2-yl) -4,4,5,5-tetramethyl-1,3,2-dioxaborolane (2- (5-hexylthiophen- 2-yl) -4,4,5,5-tetramethyl-1,3,2-dioxaborolane, Compound 3: 3.183 g, 10.82 mmol) was dissolved in THF (100 mL), then 20 mL of water, sodium carbonate ( Sodium bicarbonate: 17.36 g, 206.6 mmol) was added. After degassing with argon gas for 30 minutes, a palladium catalyst ([Pd (PPh ₃ ) ₄ ]: 1.13 g, 0.984 mmol) was added and heated, and the mixture was refluxed for 12 hours under an argon stream. After distilling off the solvent, the residue was purified by chromatography on a silica gel packed column to obtain the desired 4- (5-hexylthiophen-2-yl) phthalonitrile (Compound 4) in 2.3 g in a yield of 86.9%. It was.

(Step 3) Synthesis of Sym-HT-PcH (General Formula IV) 4- (5-Hexylthiophen-2-yl) phthalonitrile (Compound 4: 2.00 g, 6.80 mmol) synthesized in Step 1 above and Zn ( OAc) ₂ 2H ₂ O (594 mg, 2.72 mmol) was dissolved in 20 mL of pentanol. When this was heated to 100 ° C., a catalytic amount of diazabicycloundecene (DBU) was added, and then refluxed for 24 hours. After completion of the reaction, the solvent was distilled off, and the residue was purified by chromatography using a silica gel packed column. The final target product, Sym-HT-PcH (general formula IV), was 0.6 g, yield of 23%. Got in.

(Example 2) Production of Solar Cell 10 Hereinafter, as Example 2, a production example of the solar cell 10 will be described. However, it is not limited to this embodiment.

First, prepare a glass substrate (substrate 2) with a transparent conductive film formed by CVD on a transparent glass plate as a transparent substrate 21 of 20 mm x 20 mm x 2 mm and fluorine-doped tin oxide (FTO) as a transparent conductive film, and perform laser scribing. A recess 221 from which the FTO was removed was formed and washed thoroughly. Next, a dense layer (thickness 20 nm) of titanium dioxide (TiO ₂ ) to be the blocking layer 3 was formed on the entire surface of the glass substrate with a transparent conductive film by ALD (atomic layer deposition method).

On the blocking layer 3 subjected to masking, a solution obtained by diluting a commercially available TiO ₂ nanoparticle paste four times with ethanol was dropped, applied by spin coating, and dried at 80 ° C. After drying, the masking was removed, and sintering was performed at 500 ° C. for 15 minutes to form a TiO ₂ nanoparticle layer to be a porous semiconductor 41 having a thickness of 500 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. After sintering, it was allowed to cool to room temperature.

Next, an N, N-dimethylformamide solution 42 (1.2 mol / l) of lead iodide (PbI ₂ ) is prepared and dropped, and lead iodide is added into the layer composed of the porous semiconductor 41 by spin coating. After removing the permeation and excess solution, it was dried at 80 ° C. for 30 minutes.

Next, a porous semiconductor 41 containing a substrate 2, a blocking layer 3, and lead dioxide in an isopropyl alcohol solution 43 of 8 mg / ml methylammonium iodide (CH ₃ NH ₃ I, sometimes referred to as “MAI”), After dipping for 15 minutes at room temperature, irrigated with pure isopropyl alcohol solution, spin-coated, dried at 100 ° C. for 15 minutes, and then rapidly cooled to room temperature. As a result, crystals of the perovskite dye [(CH ₃ NH ₃ ) PbI ₃ ], which is the dye 44, were produced.

  Next, Sym-HT-PcH, which is a hole transport layer material, or a chlorobenzene solution of Spiro-OMeTAD (FK209, which is a cobalt dopant (Tris (2- (1H-pyrazol-1-yl) -4-tert-butylpyridine) cobalt ( III) Tris (add bis (trifluoromethylsulfonyl) imide etc. to both sides) Drop 40μl of 72.3mg / ml, remove excess solution by spin coating, and dry to make a 500nm thick hole on the power generation layer 4 A transport layer 5 was formed, and finally, a gold film was formed on the surface of the laminate 11 on which these layers were laminated by a vacuum deposition method, and an electrode 6 having a thickness of 100 nm composed of a photoelectrode 61 and a counter electrode 62 was laminated. .

(Example 3) Performance Evaluation of Solar Cell Hereinafter, as Example 3, performance evaluation of the solar cell 10 was performed.

9 and 10 are graphs showing the average battery performance of Sym-HT-PcH or Spiro-OMeTAD, FIG. 9 is Sym-HT-PcH, and FIG. 10 is Spiro-OMeTAD. 9 and 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.

ここで、形状因子FF（フィルファクター）とは、電流と電圧の積が最大となる点における最大出力Pmaxを（Voc×Jsc）で割って得られる曲線因子であり、PCEは、（Voc×Jsc×FF÷入射光強度）で計算される。 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).

  As can be understood from FIGS. 9 and 10 and Table 1, the cell performance of the solar cell using Sym-HT-PcH as the hole transport layer was about 70 to 80% of the solar cell using Spiro-OMeTAD. It was. At present, using Spiro-OMeTAD as the hole transport layer material shows higher performance, but this experiment on Sym-HT-PcH is an initial experiment. Therefore, the battery performance at a stage where conditions such as optimization for constructing the solar cell as a hole transport layer, such as solution concentration, are not performed. Other than compounds with a spiro ring structure such as Spiro-OMeTAD, none of the initial experiments has shown performance as high as Sym-HT-PcH. In addition, further performance improvement can be expected by optimizing the solution concentration, optimizing the substituents, and the like. From this point, it can be expected that the photoelectric conversion efficiency of the solar cell is greatly improved by using a phthalocyanine derivative such as Sym-HT-PcH as the hole transport layer material.

Example 4 Evaluation of Durability of Solar Cell Hereinafter, as Example 4, durability evaluation of the solar cell 10 was performed.

  The cells of the solar battery 10 produced in Example 2 were stored in a dark place in air at a temperature of 23 ° C. and a humidity of 20%, and the cell efficiency was measured periodically. At this time, the cells of the solar battery 10 were exposed to the air without being covered with a capsule or the like. The results are shown in the graph of FIG. FIG. 11 shows the change in cell efficiency over time (days), and plots the ratio of the change in cell efficiency with respect to the maximum performance value of each solar cell 10 when the maximum performance value is 1.

  From FIG. 11, the highest performance was recorded in the Sym-HT-PcH cell after two days from immediately after the production. In the Spiro-OMeTAD cell, the maximum value was recorded immediately after fabrication, and then the performance gradually decreased. Sym-HT-PcH is 78% of the maximum value after 9 days, and Spiro-OMeTAD is 58%. It can be understood that the cell using Sym-HT-PcH has higher durability.

  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 Blocking layer 4 Power generation layer 5 Hole transport layer 6 Electrode 10 Solar cell 11 Laminate 21 Transparent substrate 22 Transparent conductive film 41 Porous semiconductor 44 Dye 61 Photoelectrode 62 Counter electrode

Claims (6)

A hole transport layer material which is a compound selected from the following general formulas (I) to (III).

(In general formula (I),
M is zinc (Zn), copper (Cu), cobalt (Co), iron (Fe), nickel (Ni), lead (Pb), manganese (Mn) or tin (Zn);
R ^1a and R ^1b are independent of each other, one is selected from the following substituents (A) to (I), the other is hydrogen,
R ^2a and R ^2b are independent of each other, one is selected from the following substituents (A) to (I), the other is hydrogen,
R ^3a and R ^3b are independent of each other, one is selected from the following substituents (A) to (I), the other is hydrogen,
R ^4a and R ^4b are independent of each other, one is selected from the following substituents (A) to (I), the other is hydrogen,
The substituent selected by R ^1a or R ^1b , the substituent selected by R ^2a or R ^2b , the substituent selected by R ^3a or R ^3b , and the substituent selected by R ^4a or R ^4b are the same. is there.

Here, X ¹ of the substituent (A) is a C ₆ -C ₈ alkyl group, X ² of the substituent (B) is a C ₆ -C ₈ alkyl group, and the substituent (C X ³ is a C ₆ -C ₈ alkyl group, X ⁴ of the substituent (D) is a C ₆ -C ₈ alkyl group, and X ⁵ and X ⁶ of the substituent (E) are , The same C ₆ -C ₈ alkyl group, and X ⁷ and X ⁸ of the substituent (F) are the same C ₄ -C ₆ alkyl group or C ₁ -C ₃ alkoxy group, and the substituent X ^{9 in} (G) is a C _{4 to} C ₆ alkyl group or a diphenylamino group, and X ^{10 in the} substituent (I) is a C _{4 to} C ₆ alkyl group. )

(In the general formulas (II) and (III),
M is zinc (Zn), copper (Cu), cobalt (Co), iron (Fe), nickel (Ni), lead (Pb), manganese (Mn) or tin (Zn);
R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ , R ¹¹ , and R ¹² are the same substituent and are selected from the following (J) to (N).

Here, X ¹¹ of the substituent (J) is a C _{1 to} C ₆ alkyl group, and X ¹² of the substituent (K) is a C _{4 to} C ₆ alkyl group or a C _{1 to} C ₃ alkoxy group. Or X ¹³ and X ¹⁴ of the substituent (L) are the same C ₁ -C ₃ alkoxy group, and X ^{15 of the} substituent (M) is C ₄ -C _6. An alkyl group, and X ¹⁶ of the substituent (N) is a C ₁ -C ₃ alkoxy group or hydrogen. ) In the compound represented by the general formula (I),
The substituent (A) is a 5-hexyl-thiophen-2-yl group or a 5- (2-ethylhexyl) -thiophen-2-yl group;
The substituent (B) is a 5- (hexylsulfanyl) -thiophen-2-yl group;
The substituent (C) is a 5′-hexyl-2,2′-bithiophen-5-yl group or a 5 ′-(2-ethylhexyl) -2,2′-bithiophen-5-yl group;
The substituent (D) is a 5-hexyl-thieno [3,2-b] thiophen-2-yl group or a 5- (2-ethylhexyl) -thieno [3,2-b] thiophen-2-yl group. And
The substituent (E) is a 5,5 ″ -dihexyl-2,2 ′: 3 ′, 2 ″ -terthiophene-5′-yl group;
The substituent (F) is a bis (4-hexylphenyl) amino group, a bis (4-methoxyphenyl) amino group, or a bis (4-tert-butylphenyl) amino group;
The substituent (G) is a 4-tert-butylphenyl group or a 4- (diphenylamino) phenyl group;
The substituent (H) is a 2,6-diphenylphenoxy group;
The hole transport layer material according to claim 1, wherein the substituent (I) is a tert-butyl group. In the compound represented by the general formula (II),
The substituent (J) is a methoxy group, an ethoxy group, an isopropoxy group, a tert-butoxy group, or a hexyloxy group;
The substituent (K) is a 4-methoxyphenyl group, a 4-tert-butylphenyl group, or a 4- (diphenylamino) phenyl group;
The substituent (L) is a 3,4-dimethoxyphenyl group;
The substituent (M) is a (4-tert-butylphenyl) sulfanyl group;
The hole transport layer material according to claim 1, wherein the substituent (N) is a 2,6-diphenylphenoxy group or a 5-methoxy-2,6-diphenylphenoxy group. In the compound represented by the general formula (III),
The substituent (J) is a methoxy group, an ethoxy group, an isopropoxy group, a tert-butoxy group, or a hexyloxy group;
The substituent (K) is a 4-methoxyphenyl group, a 4-tert-butylphenyl group, or a 4- (diphenylamino) phenyl group;
The substituent (L) is a 3,4-dimethoxyphenyl group;
The substituent (M) is a (4-tert-butylphenyl) sulfanyl group;
The hole transport layer material according to claim 1, wherein the substituent (N) is a 5-methoxy-2,6-diphenylphenoxy group. The hole transport layer material according to claim 1, wherein the compound is represented by the following general formula (IV).

A substrate having a transparent conductive film,
A blocking layer for transferring electrons to the transparent conductive film and preventing reverse electron transfer;
A power generation layer formed by adsorbing to a porous semiconductor 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 photoelectrode which discharge | releases the said electron through the said transparent conductive film, and the electrode comprised by the counter electrode provided in the surface of the said hole transport layer are provided. A solar cell using the hole transport layer material described in 1.

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