JP5969892B2 - Photosensitizing dye and dye-sensitized solar cell having the same - Google Patents

Description

  The present invention relates to a photosensitizing dye and a dye-sensitized solar cell having the same.

  As a photoelectric conversion element, a dye-sensitized solar cell is attracting attention because it is inexpensive and high photoelectric conversion efficiency can be obtained, and various developments have been made regarding the dye-sensitized solar cell.

  A dye-sensitized solar cell generally includes a working electrode, a counter electrode, and an electrolyte disposed between the working electrode and the counter electrode. The working electrode has an oxide semiconductor layer, and a photosensitizing dye is adsorbed to the oxide semiconductor layer.

  In the dye-sensitized solar cell, it is important to improve the photoelectric conversion characteristics. For this reason, various proposals focusing on, for example, a photosensitizing dye have been made.

  For example, in the following non-patent document 1, tetra-n-butylammonium of cis-di (thiocyanate) bis (2,2′-bipyridyl-4,4′-dicarboxylic acid) ruthenium (II) called N719 as a photosensitizing dye. A salt is disclosed, and it is disclosed that when this photosensitizing dye is used in a dye-sensitized solar cell, a dye-sensitized solar cell having high photoelectric conversion efficiency can be obtained.

J. et al. Am. Chem. Soc. 1993, 115, 6382-6390.

  By the way, in the dye-sensitized solar cell, it is desirable that the ratio of the photoelectric conversion efficiency under high illuminance to the photoelectric conversion efficiency under low illuminance is small. This is because when the ratio of photoelectric conversion efficiency under high illuminance to photoelectric conversion efficiency under low illuminance is large, for example, when the illuminance changes from a low state to a high state, a large current suddenly increases in the dye-sensitized solar cell. This is because it may flow and the durability of the dye-sensitized solar cell may decrease.

  However, the dye-sensitized solar cell using N719 as a photosensitizing dye still has room for improvement in terms of the ratio of the photoelectric conversion efficiency under high illuminance to the photoelectric conversion efficiency under low illuminance.

  The present invention has been made in view of the above circumstances, and when used in a dye-sensitized solar cell, the ratio of the photoelectric conversion efficiency under high illuminance to the photoelectric conversion efficiency under low illuminance of the dye-sensitized solar cell is sufficient. It is an object of the present invention to provide a photosensitizing dye that can be made small and a dye-sensitized solar cell having the same.

  In order to solve the above problems, the present inventor, when used in a dye-sensitized solar cell, can obtain a photosensitizing dye that can improve the photoelectric conversion efficiency particularly under low illuminance. In dye-sensitized solar cells using sensitizing dyes, the ratio of photoelectric conversion efficiency under high illuminance to photoelectric conversion efficiency under low illuminance is considered to be sufficiently small, and intensive studies were conducted. It was.

  First, the present inventor suggested that N719 does not have a sufficiently long life of electrons excited under low illuminance, so that the dye-sensitized solar cell using N719 does not have a sufficient number of electrons that can be extracted under low illuminance. I thought that the value of the short-circuit current under illuminance might be small.

  Therefore, the present inventor introduces a group having steric hindrance into the photosensitizing dye to suppress the association of the photosensitizing dye molecules and sufficiently extend the lifetime of the electrons excited from the photosensitizing dye. I thought that I could do it. If the lifetime of the excited electrons can be made sufficiently long, the number of electrons that can be extracted from the dye-sensitized solar cell can be increased sufficiently, and as a result, the short-circuit current of the dye-sensitized solar cell under low illuminance We thought that the value of could be increased sufficiently.

  Next, the present inventor paid attention to the fact that the molar extinction coefficient in the near-ultraviolet region with a wavelength of 300 to 400 nm is small in the ultraviolet-visible absorption spectrum of the N719 Ru (II) complex-based photosensitizing dye.

  And this inventor fully introduce | transduced into the photosensitizing dye the group which has an absorption peak with a large molar extinction coefficient in the near-ultraviolet region with a wavelength of 300-400 nm, and the electron number excited from a photosensitizing dye is enough. I thought it could be increased. If the number of electrons excited from the photosensitizing dye can be increased sufficiently, the number of electrons that can be extracted from the dye-sensitized solar cell can be increased sufficiently. We thought that the value of the short circuit current of the battery could be increased sufficiently.

  As a result of intensive research based on the above idea, the present inventor has obtained a photosensitizing dye having a steric hindrance and a group having an absorption peak having a large molar extinction coefficient in the near-ultraviolet region having a wavelength of 300 to 400 nm. The present inventors have found that the above problems can be solved and have completed the present invention.

（上記式（１）中、ＭはＦｅ、Ｒｕ又はＯｓを表す。Ｎ−Ｌ−Ｎは下記一般式（２）〜（６）で表される二座の配位子を表す。ここで、Ｘ^１〜Ｘ ^４ はそれぞれ独立に、−ＣＯ_２Ｒ^１基、−ＳＯ_３Ｒ^２基、−Ｐ（＝Ｏ）（ＯＲ^３）（ＯＲ^４）基、水素原子、ハロゲン基、炭素数１〜１５の置換若しくは無置換の脂肪族炭化水素基、炭素数１〜１５の置換若しくは無置換のアルコキシ基又は炭素数１〜１５の置換若しくは無置換のチオアルコキシ基を表す。また、Ｒ^１〜Ｒ^４はそれぞれ独立に水素原子又は１価の陽イオンを表す。そして、Ｘ^１〜Ｘ^４のうち少なくとも１つは−ＣＯ_２Ｒ^１基、−ＳＯ_３Ｒ^２基又は−Ｐ（＝Ｏ）（ＯＲ^３）（ＯＲ^４）基である。Ｚはベンゼン環の数が２又は３である置換又は無置換のポリアセン基を表す。また、Ｙ^１及びＹ^２はそれぞれ独立に、−ＮＣＳ基、ハロゲン基又は−ＣＮ基を表す。また、Ｙ^１及びＹ^２は互いに結合して、下記一般式（７）で表され且つ２個の酸素原子にてＭに配位するβ−ジケトナート配位子を形成してもよい。）

（上記式（７）中、Ｒ^５及びＲ^６はそれぞれ独立に水素原子、炭素数１〜１５の置換若しくは無置換のアルキル基、置換若しくは無置換のアリール基、置換若しくは無置換のヘテロ芳香族基又は−ＣＨ＝ＣＨＲ^７を表す。Ｒ^７は置換若しくは無置換のアリール基又は置換若しくは無置換のヘテロ芳香族基を表す。）
That is, the present invention is a photosensitizing dye represented by the following general formula (1).

(In the above formula (1), M represents Fe, Ru or Os. N-L-N represents a bidentate ligand represented by the following general formulas (2) to (6). X ^{1 to} X ⁴ are each independently —CO ₂ R ¹ group, —SO ₃ R ² group, —P (═O) (OR ³ ) (OR ⁴ ) group, hydrogen atom, halogen group, carbon number 1 to 15 represents a substituted or unsubstituted aliphatic hydrocarbon group, a substituted or unsubstituted alkoxy group having 1 to 15 carbon atoms, or a substituted or unsubstituted thioalkoxy group having 1 to 15 carbon atoms, and R ^{1 to} R. ⁴ each independently represents a hydrogen atom or a monovalent cation, and at least one of X ^{1 to} X ⁴ is —CO ₂ R ¹ group, —SO ₃ R ² group or —P (═O) ( oR ³⁾ (oR ⁴⁾ is .Z represents a substituted or unsubstituted number of benzene rings is 2 or 3 groups polyacetal Represents a group. Further, ^{Y 1} and ^{Y 2} each independently represent a -NCS group, a halogen group, or -CN group. Further, ^{Y 1} and ^{Y 2} are bonded to each other, the table the following general formula (7) And a β-diketonate ligand coordinated to M by two oxygen atoms may be formed.)

(In the above formula (7), R ⁵ and R ⁶ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 15 carbon atoms, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaromatic group. A group or —CH═CHR ^7. R ⁷ represents a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaromatic group.

  According to the photosensitizing dye of the present invention, when used in a dye-sensitized solar cell, the ratio of the photoelectric conversion efficiency under high illuminance to the photoelectric conversion efficiency under low illuminance of the dye-sensitized solar cell is sufficiently reduced. be able to. Therefore, in the dye-sensitized solar cell using the photosensitizing dye, when the illuminance changes from a low state to a high state, it is sufficiently suppressed that a large current flows rapidly, and the durability of the dye-sensitized solar cell is improved. It is possible to sufficiently suppress the deterioration of the property.

  In the photosensitizing dye, M in the general formula (1) is preferably Ru.

  When this photosensitizing dye is used as a photosensitizing dye of a dye-sensitized solar cell, the durability of the dye-sensitized solar cell is particularly excellent.

In the photosensitizing dye, in the general formula (1), Y ¹ and Y ² are preferably an —NCS group.

  When this photosensitizing dye is used as the photosensitizing dye of the dye-sensitized solar cell, the photoelectric conversion efficiency of the dye-sensitized solar cell is particularly excellent.

In the photosensitizing dye, in the general formulas (1) to (6), X ^{1 to} X ⁴ are preferably each independently a hydrogen atom or a —CO ₂ R ¹ group.

  When this photosensitizing dye is used as the photosensitizing dye of the dye-sensitized solar cell, the photoelectric conversion efficiency of the dye-sensitized solar cell is particularly excellent.

  The present invention also provides a first electrode having a transparent substrate and a transparent conductive film provided on the transparent substrate, a second electrode facing the first electrode, and an oxidation provided on the first electrode or the second electrode. An organic semiconductor layer, an electrolyte provided between the first electrode and the second electrode, and a photosensitizing dye adsorbed on the oxide semiconductor layer. It is a dye-sensitized solar cell containing a sensitizing dye.

  According to the dye-sensitized solar cell of the present invention, the ratio of the photoelectric conversion efficiency under high illuminance to the photoelectric conversion efficiency under low illuminance is sufficiently reduced by including the above-described photosensitizing dye in the photosensitizing dye. be able to.

  The dye-sensitized solar cell preferably further includes a co-adsorbent adsorbed on the oxide semiconductor layer.

  In this case, compared to the case where the coadsorbent is not adsorbed on the oxide semiconductor layer, the amount of leakage current from the oxide semiconductor layer to the electrolyte can be more sufficiently suppressed, and the open circuit voltage can be more sufficiently reduced. The photoelectric conversion efficiency is particularly excellent.

  According to the present invention, when used in a dye-sensitized solar cell, the photosensitization capable of sufficiently reducing the ratio of the photoelectric conversion efficiency under high illuminance to the photoelectric conversion efficiency under low illuminance of the dye-sensitized solar cell. A dye-sensitized dye and a dye-sensitized solar cell having the same are provided.

It is sectional drawing which shows one Embodiment of the dye-sensitized solar cell of this invention. It is a figure which shows the synthetic pathway of the photosensitizing dye of this invention. It is a figure which shows the synthetic pathway of the photosensitizing dye of this invention. It is a graph which shows the ultraviolet visible (UV-vis) absorption spectrum of the photosensitizing dye which concerns on Example 1 and Comparative Example 1. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing an embodiment of the dye-sensitized solar cell of the present invention.

  As shown in FIG. 1, the dye-sensitized solar cell 100 includes a working electrode 10, a counter electrode 20 that faces the working electrode 10, and an annular sealing portion 30 that connects the working electrode 10 and the counter electrode 20. The cell space formed by the working electrode 10, the counter electrode 20, and the sealing portion 30 is filled with an electrolyte 40.

  The counter electrode 20 includes a conductive substrate 21 and a catalyst layer 22 that is provided on the side of the working electrode 10 of the conductive substrate 21 and contributes to the reduction of the electrolyte 40.

  On the other hand, the working electrode 10 includes a transparent substrate 11 and a transparent conductive substrate 15 formed of the transparent conductive film 12 provided on the transparent substrate 11 and at least one of the transparent conductive substrate 15 provided on the transparent conductive film 12. And an oxide semiconductor layer 13. The oxide semiconductor layer 13 is disposed inside the sealing portion 30. Further, both the photosensitizing dye and the co-adsorbent are adsorbed on the oxide semiconductor layer 13. The co-adsorbent is for reducing the association between the photosensitizing dyes.

The photosensitizing dye includes a photosensitizing dye represented by the following general formula (1).

In said formula (1), M represents Fe, Ru, or Os. N-L-N represents a bidentate ligand represented by the following general formulas (2) to (6). Here, X ^{1 to} X ⁴ are each independently —CO ₂ R ¹ group, —SO ₃ R ² group, —P (═O) (OR ³ ) (OR ⁴ ) group, hydrogen atom, halogen group, carbon A substituted or unsubstituted aliphatic hydrocarbon group having 1 to 15 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 15 carbon atoms, or a substituted or unsubstituted thioalkoxy group having 1 to 15 carbon atoms. R ^{1 to} R ⁴ each independently represent a hydrogen atom or a monovalent cation. At least one of X ^{1 to} X ⁴ is a —CO ₂ R ¹ group, a —SO ₃ R ² group, or a —P (═O) (OR ³ ) (OR ⁴ ) group. Z represents a substituted or unsubstituted polyacene group having 2 or 3 benzene rings. Y ¹ and Y ² each independently represent a —NCS group, a halogen group, or a —CN group. Y ¹ and Y ² may be bonded to each other to form a β-diketonate ligand represented by the following general formula (7) and coordinated to M by two oxygen atoms.

In the above formula (7), R ⁵ and R ⁶ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 15 carbon atoms, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaromatic group. or representing a -CH = CHR ^7. R ⁷ represents a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaromatic group.

  The photosensitizing dye represented by the general formula (1) has a bipyridine ligand to which a polyacene group Z having a large size and a planar shape is bonded, and in this bipyridine ligand, The molecular plane has a configuration that is twisted with respect to the molecular plane of bipyridine. Therefore, the association between the photosensitizing dyes is sufficiently suppressed by the steric hindrance derived from the bipyridine ligand. Therefore, the lifetime of electrons excited from the photosensitizing dye represented by the general formula (1) is sufficiently long. As a result, the value of the short-circuit current of the dye-sensitized solar cell 100 under low illuminance increases sufficiently.

  The photosensitizing dye represented by the general formula (1) is a polyacene group Z having a large absorption peak with a molar extinction coefficient in the near ultraviolet region of a wavelength of 300 to 400 nm where the molar extinction coefficient is small in N719. Have. Therefore, the number of electrons that can be extracted from the dye-sensitized solar cell using the photosensitizing dye represented by the general formula (1) is sufficiently increased, and the value of the short-circuit current of the dye-sensitized solar cell under low illuminance is Increase enough.

  Therefore, according to the dye-sensitized solar cell 100, the photosensitizing dye contains the photosensitizing dye represented by the general formula (1), so that the photoelectric conversion efficiency under high illuminance with respect to the photoelectric conversion efficiency under low illuminance. The ratio of conversion efficiency can be made sufficiently small. Therefore, in the dye-sensitized solar cell 100 using the photosensitizing dye, when the illuminance changes from a low state to a high state, it is sufficiently suppressed that a large current flows rapidly, and the dye-sensitized solar cell 100. It is possible to sufficiently suppress a decrease in durability.

  In the dye-sensitized solar cell 100, a co-adsorbent is adsorbed on the oxide semiconductor layer 13 in addition to the photosensitizing dye. For this reason, compared with the case where the coadsorbent is not adsorbed to the oxide semiconductor layer 13, it becomes possible to more sufficiently suppress the amount of leakage current from the oxide semiconductor layer 13 to the electrolyte 40, and to reduce the open-circuit voltage. It can increase more fully and can improve a photoelectric conversion characteristic more fully.

  Next, the working electrode 10, the counter electrode 20, the sealing part 30, the electrolyte 40, the photosensitizing dye, and the coadsorbent will be described in detail.

(Working electrode)
As described above, the working electrode 10 includes the transparent substrate 11, the transparent conductive film 12 provided on the transparent substrate 11, and at least one oxide semiconductor layer 13 provided on the transparent conductive film 12. ing.

  The material which comprises the transparent substrate 11 should just be a transparent material, for example, As such a transparent material, glass, such as borosilicate glass, soda lime glass, white plate glass, quartz glass, polyethylene terephthalate (PET), for example , Polyethylene naphthalate (PEN), polycarbonate (PC), and polyethersulfone (PES). The thickness of the transparent substrate 11 is appropriately determined according to the size of the dye-sensitized solar cell 100 and is not particularly limited, but may be, for example, in the range of 50 to 40,000 μm.

Examples of the material constituting the transparent conductive film 12 include tin-doped indium oxide (Indium-Tin-Oxide: ITO), tin oxide (SnO ₂ ), and fluorine-doped tin oxide (Fluorine-doped-Tin-Oxide: FTO). And conductive metal oxides such as The transparent conductive film 12 may be a single layer or a laminate of a plurality of layers made of different conductive metal oxides. When the transparent conductive film 12 is composed of a single layer, the transparent conductive film 12 is preferably composed of FTO because it has high heat resistance and chemical resistance. The thickness of the transparent conductive film 12 may be in the range of 0.01 to 2 μm, for example.

The oxide semiconductor layer 13 is composed of oxide semiconductor particles. Examples of the oxide semiconductor particles include titanium oxide (TiO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), niobium oxide (Nb ₂ O ₅ ), strontium titanate (SrTiO ₃ ), and tin oxide (SnO ₂ ). , Indium oxide (In ₃ O ₃ ), zirconium oxide (ZrO ₂ ), thallium oxide (Ta ₂ O ₅ ), lanthanum oxide (La ₂ O ₃ ), yttrium oxide (Y ₂ O ₃ ), holmium oxide (Ho ₂ O) ₃ ), bismuth oxide (Bi ₂ O ₃ ), cerium oxide (CeO ₂ ), aluminum oxide (Al ₂ O ₃ ), or two or more thereof. The thickness of the oxide semiconductor layer 13 may be 0.1 to 100 μm, for example.

(Counter electrode)
As described above, the counter electrode 20 includes the conductive substrate 21 and the conductive catalyst layer 22 provided on the working electrode 10 side of the conductive substrate 21 and contributing to the reduction of the electrolyte 40.

  The conductive substrate 21 is, for example, a corrosion-resistant metal material such as titanium, nickel, platinum, molybdenum, tungsten, aluminum, or stainless steel, or a film made of a conductive oxide such as ITO or FTO on the transparent substrate 11 described above. Consists of. The thickness of the conductive substrate 21 is appropriately determined according to the size of the dye-sensitized solar cell 100 and is not particularly limited, but may be, for example, 0.005 to 4 mm.

  The catalyst layer 22 is composed of platinum, a carbon-based material, a conductive polymer, or the like. Here, carbon nanotubes are suitably used as the carbon-based material.

(Sealing part)
Examples of the sealing portion 30 include thermoplastic resins such as modified polyolefin resins and vinyl alcohol polymers, and resins such as ultraviolet curable resins. Examples of modified polyolefin resins include ionomers, ethylene-vinyl acetic anhydride copolymers, ethylene-methacrylic acid copolymers, and ethylene-vinyl alcohol copolymers. These resins can be used alone or in combination of two or more.

(Electrolytes)
The electrolyte 40 contains a redox couple such as I ⁻ / I ₃ ^— and an organic solvent. As an organic solvent, acetonitrile, methoxyacetonitrile, methoxypropionitrile, propionitrile, ethylene carbonate, propylene carbonate, diethyl carbonate, γ-butyrolactone, valeronitrile, pivalonitrile, glutaronitrile, methacrylonitrile, isobutyronitrile, Phenylacetonitrile, acrylonitrile, succinonitrile, oxalonitrile, pentanitrile, adiponitrile and the like can be used. Examples of the redox pair include I ⁻ / I ₃ ^— and redox pairs such as bromine / bromide ions, zinc complexes, iron complexes, and cobalt complexes. The electrolyte 40 may use an ionic liquid instead of the organic solvent. As the ionic liquid, for example, a known iodine salt such as a pyridinium salt, an imidazolium salt, or a triazolium salt, and a room temperature molten salt that is in a molten state near room temperature is used. Examples of such room temperature molten salts include 1-hexyl-3-methylimidazolium iodide, 1-ethyl-3-propylimidazolium iodide, dimethylimidazolium iodide, ethylmethylimidazolium iodide, and dimethylpropyl. Imidazolium iodide, butylmethylimidazolium iodide, or methylpropyl imidazolium iodide is preferably used.

  In addition, the electrolyte 40 may use a mixture of the ionic liquid and the organic solvent instead of the organic solvent.

An additive can be added to the electrolyte 40. As the _{additive, LiI, I 2, 4-} t- butylpyridine, guanidinium thiocyanate, 1-methylbenzimidazole, 1-butyl-benzimidazole and the like.

Further, as the electrolyte 40, a nano-composite gel electrolyte, which is a pseudo-solid electrolyte formed by kneading nanoparticles such as SiO ₂ , TiO ₂ , carbon nanotubes, etc. into the electrolyte, may be used, and polyvinylidene fluoride may be used. Alternatively, an electrolyte gelled with an organic gelling agent such as a polyethylene oxide derivative or an amino acid derivative may be used.

(Photosensitizing dye)
The photosensitizing dye is represented by the general formula (1).

  As described above, according to the dye-sensitized solar cell 100, the photosensitizing dye contains the photosensitizing dye represented by the general formula (1), so that high illuminance with respect to photoelectric conversion efficiency under low illuminance. The ratio of the photoelectric conversion efficiency below can be made sufficiently small.

Further, as described above, the photosensitizing dye represented by the general formula (1) has a polyacene group Z having steric hindrance. The coordination bonds MY ¹ and MY ² are sterically protected by this Z. This makes it difficult for the ligands Y ¹ and Y ² of the photosensitizing dye to be replaced by H ₂ O or the like. Therefore, the photosensitizing dye and the dye-sensitized solar cell 100 using the photosensitizing dye have excellent durability.

  In the general formula (1), M is preferably Ru. In this case, when the dye-sensitized solar cell 100 is operated, the oxidized species of Ru generated in the electron transfer process after the photosensitized dye is photoexcited becomes stable, and thus the dye-sensitized solar cell 100. The durability is particularly excellent.

  Examples of the polyacene group Z include a substituted or unsubstituted naphthyl group and a substituted or unsubstituted anthracyl group.

  Examples of the substituent of the polyacene group Z include a halogen group, a hydrocarbon group having 1 to 15 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 15 carbon atoms, and a substituted or unsubstituted group having 1 to 15 carbon atoms. Examples include thioalkoxy groups. Examples of the hydrocarbon group include a substituted or unsubstituted phenyl group and a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 15 carbon atoms.

  Examples of the halogen group include a —Cl group, a —Br group, and a —I group.

  Moreover, as a substituent of a phenyl group, a halogen group, a nitro group, a C1-C15 alkyl group, a C1-C15 alkoxy group, a C1-C15 thioalkoxy group etc. are mentioned, for example. Specific examples of the substituted phenyl group include 3,4,5-trimethylphenyl group and 3,5-difluorophenyl group.

Moreover, as said C1-C15 aliphatic hydrocarbon group, a C1-C15 alkyl group etc. are mentioned, for example. Specific examples of the alkyl group having 1 to 15 carbon atoms include a branched alkyl group such as tert-butyl group and a linear alkyl group such as —C ₉ H ₁₉ . Examples of the substituent of the aliphatic hydrocarbon group include a halogen group, a nitro group, an alkyl group having 1 to 15 carbon atoms, an alkoxy group having 1 to 15 carbon atoms, and a thioalkoxy group having 1 to 15 carbon atoms.

  Examples of the substituent for the alkoxy group having 1 to 15 carbon atoms include a halogen group, a nitro group, an alkyl group having 1 to 15 carbon atoms, an alkoxy group having 1 to 15 carbon atoms, and a thioalkoxy group having 1 to 15 carbon atoms. Group and the like.

  Examples of the substituent for the thioalkoxy group having 1 to 15 carbon atoms include a halogen group, a nitro group, an alkyl group having 1 to 15 carbon atoms, an alkoxy group having 1 to 15 carbon atoms, and a thio group having 1 to 15 carbon atoms. An alkoxy group etc. are mentioned.

As the substituent that the polyacene group Z has, —C ₉ H ₁₉ , tert-butyl group, or 3,4,5-trimethylphenyl group is particularly preferable. In this case, the steric hindrance of the polyacene group becomes particularly large, and the association of the photosensitizing dye molecules is particularly effectively suppressed.

  As described above, in the general formula (1), N-L-N is a bidentate coordination represented by the general formula (2), (3), (4), (5) or (6). A child.

  When the N-L-N is a ligand represented by the general formula (2), the solubility of the photosensitizing dye in an organic solvent is particularly excellent.

  Moreover, when said N-L-N is a ligand represented by the said General formula (3), a photosensitizing dye will have 2 Z per molecule. Therefore, the association of photosensitizing dye molecules is further effectively suppressed. The photosensitizing dye has an absorption peak with a larger molar extinction coefficient in the near-ultraviolet region with a wavelength of 300 to 400 nm.

  Moreover, when said N-L-N is a ligand represented by the said General formula (4), a photosensitizing dye will have an absorption peak further in the wavelength range of 300-600 nm.

  Moreover, when the said N-L-N is a ligand represented by the said General formula (5), a photosensitizing dye will have an absorption peak further in the wavelength range of 800-1000 nm.

  Further, when the NL—N is a ligand represented by the general formula (6), the photosensitizing dye has a configuration in which the NL—N is represented by the general formula (5). Similar to the case of a ligand, it has an absorption peak in a wavelength region of 800 to 1000 nm. In this case, the photosensitizing dye has two quinoline sites per molecule. Therefore, the absorbance at the absorption peak at a wavelength of 800 to 1000 nm is even greater than when N-L-N is a ligand represented by the general formula (5).

As described above, in the general formulas (1) to (6), X ^{1 to} X ⁴ are each independently —CO ₂ R ¹ group, —SO ₃ R ² group, —P (═O) (OR ³ ). ) (OR ⁴ ) group, hydrogen atom, halogen group, substituted or unsubstituted aliphatic hydrocarbon group having 1 to 15 carbon atoms, substituted or unsubstituted alkoxy group having 1 to 15 carbon atoms, or 1 to 15 carbon atoms A substituted or unsubstituted thioalkoxy group is represented.

  Examples of the halogen group include a —Cl group, a —Br group, and a —I group.

  Moreover, as said C1-C15 aliphatic hydrocarbon group, an alkyl group etc. are mentioned, for example. Examples of the substituent of the aliphatic hydrocarbon group include a halogen group, a nitro group, an alkyl group having 1 to 15 carbon atoms, an alkoxy group having 1 to 15 carbon atoms, and a thioalkoxy group having 1 to 15 carbon atoms.

  Examples of the substituent for the alkoxy group having 1 to 15 carbon atoms include a halogen group, a nitro group, an alkyl group having 1 to 15 carbon atoms, an alkoxy group having 1 to 15 carbon atoms, and a thioalkoxy group having 1 to 15 carbon atoms. Group and the like.

  Examples of the substituent for the thioalkoxy group having 1 to 15 carbon atoms include a halogen group, a nitro group, an alkyl group having 1 to 15 carbon atoms, an alkoxy group having 1 to 15 carbon atoms, and a thio group having 1 to 15 carbon atoms. An alkoxy group etc. are mentioned.

R ^{1 to} R ⁴ each independently represent a hydrogen atom or a monovalent cation. At least one of X ^{1 to} X ⁴ is a —CO ₂ R ¹ group, a —SO ₃ R ² group, or a —P (═O) (OR ³ ) (OR ⁴ ) group.

Examples of the monovalent cation include metal cations such as Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , and Cs ^+, and ammonium ions represented by the following general formula (8).

In said formula (8), R < ⁸ > -R < ¹¹ > represents a hydrogen atom or a C1-C15 substituted or unsubstituted aliphatic hydrocarbon group each independently. Here, examples of the aliphatic hydrocarbon group include an alkyl group. Examples of the substituent of the aliphatic hydrocarbon group include a halogen group, a nitro group, an alkyl group having 1 to 15 carbon atoms, an alkoxy group having 1 to 15 carbon atoms, and a thioalkoxy group having 1 to 15 carbon atoms.

Here, it is preferable that all of R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ are butyl groups. In this case, the solubility of the photosensitizing dye in an organic solvent is improved.

X ^{1 to} X ⁴ are preferably each independently a hydrogen atom or a —CO ₂ R ¹ group. In this case, the photoelectric conversion efficiency of the dye-sensitized solar cell 100 can be particularly effectively improved.

As described above, in the general formula (1), Y ¹ and Y ² each independently represent a —NCS group, a halogen group, or a —CN group. Y ¹ and Y ² may be bonded to each other to form a β-diketonate ligand represented by the general formula (7) and coordinated to M by two oxygen atoms.

  Examples of the halogen group include a —Cl group, a —Br group, and a —I group.

In the β-diketonate ligand represented by the above general formula (7) and coordinated to M by two oxygen atoms, R ⁵ and R ⁶ are each independently a hydrogen atom, having 1 to 15 carbon atoms. It represents a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaromatic group, or —CH═CHR ⁷ . R ⁷ represents a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaromatic group.

  Examples of the heteroaromatic group include sulfur atom-containing heteroaromatic groups such as thiophenyl group, benzothiophenyl group, thienothiophenyl group, and dibenzothiophenyl group, nitrogen such as pyridyl group, pyrimidyl group, quinolyl group, and indolyl group. An oxygen atom-containing heteroaromatic group such as an atom-containing heteroaromatic group, a furyl group, or a benzofuryl group is exemplified.

In the general formula (1), Y ¹ and Y ² are preferably —NCS groups. In this case, since the photosensitizing dye has an absorption peak having a large molar extinction coefficient, the photoelectric conversion efficiency of the dye-sensitized solar cell 100 can be effectively improved.

  Here, the method for synthesizing the photosensitizing dye will be described in detail with reference to FIGS. 2 and 3 are diagrams showing the synthesis route of the photosensitizing dye of the present invention.

As shown in FIG. 2, when synthesizing a photosensitizing dye in which Y ¹ and Y ² are both Y ³ in the general formula (1), that is, a photosensitizing dye represented by the general formula (14), By reacting the starting metal salt represented by the general formula (9) or (10) with the Z-substituted bipyridine ligand represented by the general formula (11), an intermediate represented by the general formula (12) is obtained. After being obtained, this intermediate may be reacted with the bidentate ligand N—L—N represented by the general formula (13). Here, Y ³ represents a halogen group such as a —Cl group, a —Br group, and a —I group. “Solv” in the general formula (12) represents a solvent molecule coordinated to M.

  Here, the raw material metal salt represented by the general formula (9) is used when M is Fe in the general formula (1). The raw material metal salt represented by the general formula (10) is used when M is Ru or Os in the general formula (1). When M is Ru, it is preferable to use a dihalo (cymene) ruthenium dimer as the starting metal salt represented by the general formula (10), and when M is Os, a dihalo (cymene) osmium dimer is used. It is preferable.

  The Z-substituted bipyridine ligand represented by the general formula (11) can be synthesized by a known synthesis method such as cross coupling.

  Similarly, the bidentate ligand N-L-N represented by the general formula (13) can also be synthesized by a known synthesis method such as cross coupling.

Further, as shown in FIG. 3, when synthesizing a photosensitizing dye in which Y ¹ and Y ² are both Y ⁴ in the general formula (1), that is, a photosensitizing dye represented by the general formula (16). By reacting the photosensitizing dye (14) represented by the general formula (14) with the tetraalkylammonium salt (R ¹² ) ₄ NY ⁴ represented by the general formula (15), Y ³ is converted into Y ⁴ may be substituted. Here, ^{Y 4} represents a -NCS group or -CN group. R ¹² represents an alkyl group such as a methyl group, an ethyl group, a propyl group, or a butyl group. Further, different types of tetraalkylammonium salts (R ¹² ) ₄ NY ⁴ are sequentially reacted with a photosensitizing dye represented by the above general formula (14) to thereby cause photosensitization represented by the general formula (16). Two Y ⁴ coordinated to M in the dye may be different from each other.

As shown in FIG. 2, when the photosensitizing dye represented by the general formula (14) is synthesized, the precursor of the photosensitizing dye represented by the general formula (14), that is, the general formula ( The intermediate represented by 12) is a step in which the starting metal salt (9) or (10) is reacted with the Z-substituted bipyridine ligand represented by the general formula (11) in the general formula (12 ′). Obtained as a mixture with the represented geometric isomer. Therefore, when this mixture is reacted with the bidentate ligand N—L—N represented by the general formula (13), the photosensitizing dye represented by the general formula (14) and the general formula (14 ′) A mixture with the geometric isomer represented by the formula (hereinafter referred to as “mixture A”) is obtained. As shown in FIG. 3, when this mixture A is reacted with a tetraalkylammonium salt (R ¹² ) ₄ NY ⁴ represented by the general formula (15), the light represented by the general formula (16) is obtained. A mixture of the sensitizing dye and the geometric isomer represented by the general formula (16 ′) (hereinafter referred to as “mixture B”) is obtained. The mixture A and the mixture B can be separated by a known purification method. The photosensitizing dye should just contain the photosensitizing dye represented by General formula (14) or (16). Therefore, the photosensitizing dye may be composed of the mixture A or the mixture B.

(Co-adsorbent)
The coadsorbent is not particularly limited as long as it suppresses the association of the photosensitizing dyes. As the coadsorbent, an organic compound represented by the following general formula (17) or a salt thereof may be used. Here, the organic compound is composed of only nonmetallic atoms.

In the above formula (17), n represents an integer of 0 to 5, and R ¹⁴ represents a monovalent group having a steroid skeleton.

  n is preferably an integer of 0 to 2.

As the monovalent group having a steroid skeleton, for example, a monovalent group represented by the following general formula (18) is used.

In the above formula (10), R ¹⁵ , R ¹⁶ and R ¹⁷ each independently represents a hydrogen atom or a hydroxyl group.

  Specific examples of the coadsorbent having a steroid skeleton include deoxycholic acid, chenodeoxycholic acid, cholic acid, hyodeoxycholic acid, and salts thereof.

  The molar ratio of the co-adsorbent to the photosensitizing dye is usually 0.5 to 200, preferably 10 to 100. When the molar ratio of the co-adsorbent to the photosensitizing dye is within the above range, the leakage current can be more effectively reduced and the generated current can be further increased as compared with a case outside the above range. it can.

  Next, the manufacturing method of the dye-sensitized solar cell 100 described above will be described.

  First, a transparent conductive substrate 15 formed by forming a transparent conductive film 12 on one transparent substrate 11 is prepared.

  As a method for forming the transparent conductive film 12, a sputtering method, a vapor deposition method, a spray pyrolysis (SPD) method, a CVD method, or the like is used.

  Next, the oxide semiconductor layer 13 is formed over the transparent conductive film 12. The oxide semiconductor layer 13 is formed by printing a porous oxide semiconductor layer forming paste containing oxide semiconductor particles, followed by firing.

  The oxide semiconductor layer forming paste includes a resin such as polyethylene glycol and a solvent such as terpineol in addition to the oxide semiconductor particles described above.

  As a method for printing the oxide semiconductor layer forming paste, for example, a screen printing method, a doctor blade method, a bar coating method, or the like can be used.

  The firing temperature varies depending on the material of the oxide semiconductor particles, but is usually 350 to 600 ° C., and the firing time also varies depending on the material of the oxide semiconductor particles, but is usually 1 to 5 hours.

  Thus, the working electrode 10 is obtained.

  Next, the photosensitizing dye synthesized as described above is adsorbed on the surface of the oxide semiconductor layer 13 of the working electrode 10. For this purpose, the working electrode 10 is immersed in a solution containing a photosensitizing dye, the photosensitizing dye is adsorbed on the oxide semiconductor layer 13, and then the excess photosensitizer is added with the solvent component of the solution. The photosensitizing dye may be adsorbed to the oxide semiconductor layer 13 by washing away the dye and drying it. However, the photosensitizing dye may be adsorbed to the oxide semiconductor layer 13 by applying a solution containing the photosensitizing dye to the oxide semiconductor layer 13 and then drying the solution.

  Next, the coadsorbent described above is adsorbed on the surface of the oxide semiconductor layer 13 of the working electrode 10. For this purpose, the working electrode 10 is immersed in a solution containing a co-adsorbent, the co-adsorbent is adsorbed on the oxide semiconductor layer 13, and then the extra co-adsorbent is removed with the solvent component of the solution. The co-adsorbent may be adsorbed on the surface of the oxide semiconductor layer 13 by washing and drying. However, the coadsorbent may be adsorbed to the oxide semiconductor layer 13 by applying a solution containing the coadsorbent to the oxide semiconductor layer 13 and then drying the solution.

  At this time, the co-adsorbent is adsorbed on the surface of the oxide semiconductor layer 13 in a region where the photosensitizing dye is not adsorbed.

  Note that the co-adsorbent may be mixed with a photosensitizing dye and simultaneously adsorbed on the surface of the oxide semiconductor layer 13. In this case, the oxide semiconductor layer 13 may be immersed in a solution containing a photosensitizing dye and a coadsorbent. At this time, the immersion time of the oxide semiconductor layer 13 in the solution is preferably 10 to 48 hours, and more preferably 15 to 25 hours.

  Next, the electrolyte 40 is disposed on the oxide semiconductor layer 13. The electrolyte 40 can be disposed by a printing method such as screen printing.

  Next, an annular sealing portion forming body is prepared. The sealing part forming body can be obtained, for example, by preparing a sealing resin film and forming one rectangular opening in the sealing resin film.

  Then, the sealing portion forming body is bonded onto the working electrode 10. At this time, adhesion of the sealing portion forming body to the working electrode 10 can be performed by, for example, heating and melting the sealing portion forming body.

  Next, the counter electrode 20 is prepared and disposed so as to close the opening of the sealing portion forming body, and then bonded to the sealing portion forming body. At this time, the sealing portion forming body may be bonded to the counter electrode 20 in advance, and the sealing portion forming body may be bonded to the sealing portion forming body on the working electrode 10 side. Lamination of the counter electrode 20 to the sealing portion forming body may be performed under atmospheric pressure or under reduced pressure, but is preferably performed under reduced pressure.

  The dye-sensitized solar cell 100 is obtained as described above.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the porous oxide semiconductor layer 13 is provided on the transparent conductive film 12 of the transparent conductive substrate 15 to receive light from this side, but the porous oxide semiconductor layer 13 is formed. An opaque material (for example, a metal substrate) may be used for the base material to be formed, a transparent material may be used for the base material for forming the counter electrode 20, and a structure for receiving light from the counter electrode side may be employed. I do not care.

  In the above embodiment, the co-adsorbent is adsorbed on the surface of the oxide semiconductor layer 13 of the working electrode 10, but the co-adsorbent is not necessarily used.

  Furthermore, in the said embodiment, although the photosensitizing dye contains the photosensitizing dye represented by the said General formula (1), this 1st photosensitizing dye is used as this 1st photosensitizing dye. A second photosensitizing dye different from the sensitive dye may be further contained.

  Here, as the second photosensitizing dye, a photosensitizing dye having an absorption peak on a shorter wavelength side than the absorption peak wavelength of the first photosensitizing dye is preferable.

  The absorption peak wavelength of the second photosensitizing dye is preferably on the shorter wavelength side than the absorption peak wavelength of the first photosensitizing dye. In this case, the photoelectric conversion characteristics can be further improved. Here, the absorption peak wavelength of the second photosensitizing dye is preferably 300 to 500 nm, and more preferably 300 to 450 nm.

  As such a second photosensitizing dye, those having a molar extinction coefficient at the absorption peak wavelength larger than the molar extinction coefficient at the absorption peak wavelength of the first photosensitizing dye are preferably used. In this case, it is possible to have more excellent light absorption characteristics over a wide wavelength region.

As such a second photosensitizing dye, a dye represented by the following general formula (19) is used.

In the above formula ^(19), in each of ^{R 18} and ^{R 19} independently represent a hydrogen atom, -CN, -COOH, or a hydrocarbon group having 1 to 5 carbon ^atoms, R ^20, R ^{21, R 23} and R ²⁴ each independently represents a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, and R ²² is a phenyl group substituted with an alkoxy group having 1 to 5 carbon atoms, or represented by the following general formula (20). Represents a substituent. R ²³ and R ²⁴ may combine with each other to form a 5-membered ring or a 6-membered ring.

In the above formula (20), R ²⁵ , R ²⁶ , R ²⁷ and R ²⁸ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms.

Specific examples of the dye represented by the general formula (19) include those represented by the following structural formulas (21) and (22).

  The absorption peak wavelength of the second photosensitizing dye (D131) represented by the structural formula (21) is 420 nm, and the absorption peak wavelength of the second photosensitizing dye represented by the structural formula (22) is as follows. Is 395 nm.

As the second photosensitizing dye, a dye represented by the following general formula (23) can also be used.

In the above formula ^{(23), R 29} represents a hydrogen atom or a _{^{-C 6 H 4 NR 31 R 32}} , R 30 represents _{^{-C 6 H 4 NR 31 R 32}} . R ³¹ and R ³² each independently represents an alkyl group having 1 to 10 carbon atoms.

Of the photosensitizing dyes represented by the general formula (23), a dye in which R ²⁹ represents a hydrogen atom and R ³⁰ represents —C ₆ H ₄ NR ³¹ R ³² is preferable. In this case, the photoelectric conversion characteristics tend to be further improved.

Specific examples of the photosensitizing dye represented by the general formula (23) include those represented by the following structural formulas (24) and (25).

  The absorption peak wavelength of the second photosensitizing dye (NKX-2553) represented by the structural formula (24) is 455 nm, and the second photosensitizing dye (NKX) represented by the structural formula (25) is used. The absorption peak wavelength of −2554) is 465 nm.

  Hereinafter, the content of the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples.

<Synthesis of photosensitizing dye>
(Synthesis Example 1)
Synthesis of 6- (2-naphthyl) -2,2′ -bipyridine-4,4′-dicarboxylic acid 1.34 g of dimethyl 6-chloro-2,2′-bipyridine-4,4′-dicarboxylic acid was added to 240 ml of tetrahydrofuran. Dissolved to obtain a solution. Then, 1.34 g of 2-naphthylboronic acid pinacol ester, 0.25 g of tetrakis (triphenylphosphine) palladium (0), 0.56 g of sodium carbonate and 50 ml of water were added to this solution to obtain a reaction solution. The reaction solution was heated to reflux for 2 hours under an argon atmosphere to carry out the reaction. After completion of the reaction, the obtained solution was allowed to stand to separate into an aqueous layer and an organic layer. The aqueous layer was extracted with chloroform, and the extract obtained by this extraction was combined with the organic layer to form one organic layer. The organic layer was washed with saturated brine. Next, after separating the organic layer from the saturated saline solution, the organic layer was dried over magnesium sulfate, and the solvent was distilled off from the organic layer under reduced pressure to obtain a crude product. The obtained crude product was recrystallized with chloroform to obtain 1.19 g of a solid. When NMR was measured for this solid, the results were as follows.

¹ H-NMR (270 MHz / CDCl ₃ ) δ (ppm): 4.04 (s, 6H), 7.55 (m, 2H), 7.92 (m, 2H), 8.02 (m, 2H) , 8.40 (d, 1H), 8.52 (s, 1H), 8.66 (s, 1H), 8.89 (d, 1H), 8.93 (s, 1H), 9.17 ( s, 1H)

  From the above results, it was found that the solid was dimethyl 6- (2-naphthyl) -2,2'-bipyridine-4,4'-dicarboxylate.

  Dimethyl 6- (2-naphthyl) -2,2'-bipyridine-4,4'-dicarboxylate obtained as described above was added to a methanol-water mixed solvent to obtain a suspension. Then, 6- (2-naphthyl) -2,2'-bipyridine-4,4'-dicarboxylic acid was obtained by adding sodium hydroxide to the suspension and heating to reflux.

Synthesis of (2,2′-bipyridine-4,4′-dicarboxylic acid) [6- (2-naphthyl) -2,2′-bipyridine-4,4′-dicarboxylic acid] dithiocyanate toruthenium (II) 110 mg of 6- (2-naphthyl) -2,2′-bipyridine-4,4′-dicarboxylic acid and 90 mg of dichloro (p-cymene) ruthenium (II) dimer obtained as described above were dissolved in 40 ml of dimethylformamide. And stirred at 80 ° C. for 4 hours under an argon atmosphere to obtain a reaction solution. Subsequently, 38 mg of 2,2′-bipyridine-4,4′-dicarboxylic acid was added to the reaction solution, and the mixture was heated to reflux at 140 ° C. for 4 hours. Further, 2.7 g of tetrabutylammonium thiocyanate was added to this reaction solution, and the mixture was heated to reflux at 140 ° C. for 4 hours. After completion of the heating, the solvent was distilled off from the obtained solution under reduced pressure, and the residue was dissolved in 0.1 M tetrabutylammonium hydroxide aqueous solution. And the nitric acid was added to the obtained solution, pH was adjusted to 3.4, and the deposit was obtained. Subsequently, the resulting precipitate was filtered to obtain a crude product. The crude product was purified by column chromatography (filler: Sephadex LH-20, eluent: water) to obtain 130 mg of a solid. When NMR and MS (mass spectrum) of this solid were measured, the results were as shown below.

¹ H-NMR (270 MHz / CD ₃ OD) δ (ppm): 6.22 (d), 6.53 (s), 6.94 (d), 7.15-7.38 (d), 7. 42-7.90 (m), 7.90-8.11 (m), 8.23 (m), 8.32 (s), 8.58 (m), 8.71 (d), 9. 00 (s), 9.17 (s), 9.52 (d)
MS (ESI-MS): m / z = 830.5

  From the above results, the solid was found to be (2,2′-bipyridine-4,4′-dicarboxylic acid) [6- (2-naphthyl) -2,2′-bipyridine-4,4′-dicarboxylic acid] dithiocyanate. It was found to be natrethenium (II).

Example 1
First, a transparent conductive substrate was prepared by forming a transparent conductive film made of FTO having a thickness of 1 μm on a transparent substrate made of glass having a thickness of 1 mm.

  Next, an oxide semiconductor layer forming paste containing titania was applied onto the transparent conductive film and dried, followed by baking at 500 ° C. for 1 hour. Thus, a working electrode having a porous oxide semiconductor layer having a thickness of 40 μm was obtained.

  Next, the working electrode was immersed in the dye solution for a whole day and night, then taken out and dried, and a photosensitizing dye was supported on the oxide semiconductor layer. The dye solution was prepared by dissolving the photosensitizing dye of Synthesis Example 1 obtained as described above in a 1-propanol solvent so as to be 0.2 mM.

Next, an electrolyte was applied on the porous oxide semiconductor layer. Electrolyte in a solvent consisting of acetonitrile was prepared by dissolving lithium iodide so as 2.0 M, the I ₂ and 0.05 M.

  Next, the sealing part formation body for forming a sealing part was prepared. The sealing portion forming body is prepared by preparing a single sealing resin film made of 10 mm × 10 mm × 50 μm ionomer (trade name: High Milan, Mitsui / DuPont Polychemical Co., Ltd.) Obtained by forming a square opening. At this time, the opening had a size of 6 mm × 6 mm × 50 μm.

  And after mounting this sealing part formation body on a working electrode, the sealing part formation body was adhere | attached on the working electrode by heat-melting.

  Next, a counter electrode was prepared. The counter electrode was prepared by forming a catalyst layer made of platinum having a thickness of 600 nm on a 15 mm × 15 mm × 1 mm FTO conductive glass substrate by sputtering. Further, another sealing part forming body was prepared, and this sealing part forming body was adhered to the surface of the counter electrode facing the working electrode in the same manner as described above.

  And the sealing part formation body adhere | attached on the working electrode and the sealing part formation body adhere | attached on the counter electrode were made to oppose, and the sealing part formation bodies were piled up. And in this state, the sealing part forming body was heated and melted while being pressurized. Thus, a sealing portion was formed between the working electrode and the counter electrode.

  Thus, a dye-sensitized solar cell was obtained.

(Comparative Example 1)
A dye-sensitized solar cell was produced in the same manner as in Example 1 except that N719 was used as the photosensitizing dye.

<Evaluation of characteristics>
(1) Evaluation of Photosensitizing Dye The photosensitizing dyes of Synthesis Example 1 and Comparative Example 1 were each dissolved in ethanol to form a 0.05 mM solution, and an ultraviolet-visible (UV-vis) spectrophotometer (manufactured by Shimadzu Corporation) The absorbance was measured with a product name UV2550) to obtain a spectrum of molar extinction coefficient. The results are shown in FIG. In FIG. 4, the solid line is the absorption spectrum of Example 1 and the broken line is the absorption spectrum of Comparative Example 1.

(2) Evaluation of photoelectric conversion characteristics of dye-sensitized solar cell First, the dye-sensitized solar cell of Example 1 and Comparative Example 1 was irradiated using a solar simulator (manufactured by Yamashita Denso Co., Ltd., product name YSS-150A). The photoelectric conversion efficiency η ₁ (%) under the conditions of light 100 mW / cm ³ (1 sun) and air mass 1.5 was measured, and this was defined as the photoelectric conversion efficiency under high illuminance.

Next, for the dye-sensitized solar cells of Example 1 and Comparative Example 1, a solar simulator (manufactured by Yamashita Denso Co., Ltd., product name YSS-150A) was applied under conditions of irradiation light of 100 mW / cm ³ (1 sun) and air mass 1.5 And a shadow is formed on the dye-sensitized solar cell using a mesh so that the amount of light actually received by the dye-sensitized solar cell is 10 mW / cm ³ (0.1 sun), and the photoelectric conversion efficiency η ₂ ( %), And this was defined as the photoelectric conversion efficiency under low illuminance.

Then, the “photoelectric conversion efficiency ratio η” defined by the following equation was calculated using the photoelectric conversion efficiency η _{2 at} low illuminance and the photoelectric conversion efficiency η ₁ under high illuminance.
Photoelectric conversion efficiency ratio η = η ₁ / η ₂
The values of the photoelectric conversion efficiency ratio η are shown in Table 1 for Examples 1 to 5 and Comparative Example 1.

  From the results shown in FIG. 4, the molar extinction coefficient of the photosensitizing dye of Example 1 is larger than the molar extinction coefficient of the photosensitizing dye of Comparative Example 1 in the near ultraviolet region of 300 to 400 nm. I understood.

  From the results shown in Table 1, the dye-sensitized solar cell of Example 1 has a sufficiently small photoelectric conversion efficiency ratio η as compared with the dye-sensitized solar cell of Comparative Example 1, that is, low illuminance. It was found that the ratio of the photoelectric conversion efficiency under high illuminance to the photoelectric conversion efficiency below becomes sufficiently small.

  From the above, according to the photosensitizing dye of the present invention, when used in a dye-sensitized solar cell, the ratio of the photoelectric conversion efficiency under high illuminance to the photoelectric conversion efficiency under low illuminance of the dye-sensitized solar cell is sufficient. It was confirmed that it can be made smaller.

DESCRIPTION OF SYMBOLS 10 ... Working electrode 11 ... Transparent substrate 12 ... Transparent conductive film 13 ... Oxide semiconductor layer 15 ... Transparent conductive substrate (1st electrode)
20 ... Counter electrode (second electrode)
40 ... Electrolyte 100 ... Dye-sensitized solar cell

Claims (6)

A photosensitizing dye represented by the following general formula (1).

(In the above formula (1), M represents Fe, Ru or Os. N-L-N represents a bidentate ligand represented by the following general formulas (2) to (6). X ^{1 to} X ⁴ are each independently —CO ₂ R ¹ group, —SO ₃ R ² group, —P (═O) (OR ³ ) (OR ⁴ ) group, hydrogen atom, halogen group, carbon number 1 to 15 represents a substituted or unsubstituted aliphatic hydrocarbon group, a substituted or unsubstituted alkoxy group having 1 to 15 carbon atoms, or a substituted or unsubstituted thioalkoxy group having 1 to 15 carbon atoms, and R ^{1 to} R. ⁴ each independently represents a hydrogen atom or a monovalent cation, and at least one of X ^{1 to} X ⁴ is —CO ₂ R ¹ group, —SO ₃ R ² group or —P (═O) ( oR ³⁾ (oR ⁴⁾ is .Z represents a substituted or unsubstituted number of benzene rings is 2 or 3 groups polyacetal Represents a group. Further, ^{Y 1} and ^{Y 2} each independently represent a -NCS group, a halogen group, or -CN group. Further, ^{Y 1} and ^{Y 2} are bonded to each other, the table the following general formula (7) And a β-diketonate ligand coordinated to M by two oxygen atoms may be formed.)

(In the above formula (7), R ⁵ and R ⁶ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 15 carbon atoms, a substituted or unsubstituted aryl group, a substituted or unsubstituted heteroaromatic group. A group or —CH═CHR ^7. R ⁷ represents a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaromatic group.   The photosensitizing dye according to claim 1, wherein in the general formula (1), M is Ru. The photosensitizing dye according to claim 1 or 2, wherein Y ¹ and Y ² in the general formula (1) are -NCS groups. In Formula ^{(1) ~ (6),} X 1 ~X 4 photosensitizer dye according to any one of claims 1 to 3 are each independently hydrogen atom or a _-CO 2 ^{R 1} group. A first electrode having a transparent substrate and a transparent conductive film provided on the transparent substrate;
A second electrode facing the first electrode;
An oxide semiconductor layer provided on the first electrode or the second electrode;
An electrolyte provided between the first electrode and the second electrode;
A photosensitizing dye adsorbed on the oxide semiconductor layer;
With
The dye-sensitized solar cell in which the said photosensitizing dye contains the photosensitizing dye as described in any one of Claims 1-4. The dye-sensitized solar cell according to claim 5, further comprising a co-adsorbent adsorbed on the oxide semiconductor layer.

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