JP2018129415A - Photoelectric conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element having excellent endurance under both heat cycle environment and high humidity environment.SOLUTION: A photoelectric conversion element includes at least one photoelectric conversion cell, having an electrode substrate, a counter substrate facing the electrode substrate, and an annular sealing part for joining the electrode substrate and the counter substrate, and provided therebetween. The sealing part contains at least one kind selected from a group consisting of acid-modified polyethylene, ethylene-vinyl alcohol copolymer and polyvinyl alcohol, thickness of the sealing part is 50 μm or less, and in Raman spectrum obtained by performing microscopic Raman scattering measurement for the sealing part, the value of R represented by following formula (1) is 1.15 or more, where Iis the peak strength in a region where Raman shift is 2845-2851 cm, and Iis the peak strength in a region where Raman shift is 2879-2885 cm. R=I/I... (1).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a photoelectric conversion element.

  As a photoelectric conversion element, a photoelectric conversion element using a dye is attracting attention because it is inexpensive and high photoelectric conversion efficiency is obtained, and various developments have been made on photoelectric conversion elements using a dye.

  As a photoelectric conversion element using a dye, for example, a photoelectric conversion element described in Patent Document 1 below is known. In the following Patent Document 1, the photoelectric conversion element includes at least one photoelectric conversion cell, and the photoelectric conversion cell is an annular substrate that joins the electrode substrate, the counter substrate facing the electrode substrate, and the electrode substrate and the counter substrate. And having a sealing portion. Patent Document 1 also discloses that the sealing portion is made of a modified polyolefin resin or a vinyl alcohol polymer.

JP 2006-207949 A

  However, the photoelectric conversion element described in Patent Document 1 described above still has room for improvement in terms of durability in either a heat cycle environment or a high humidity environment.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a photoelectric conversion element having excellent durability in both a heat cycle environment and a high humidity environment.

The present inventors examined the cause of the above problem. As a result, in the photoelectric conversion element described in Patent Document 1, by setting the thickness of the sealing portion to 50 μm or less, it is possible to reduce the moisture cross-sectional area in the sealing portion, and in a high humidity environment. I thought that it would be possible to improve the durability. However, if the thickness of the sealing portion is made too small, the adhesion of the sealing portion to the electrode substrate or the counter substrate is reduced, and the sealing portion is easily peeled off from the electrode substrate or the counter substrate. Durability at low. Accordingly, the present inventors have further studied in order to realize a photoelectric conversion element having excellent durability in both a heat cycle environment and a high humidity environment. As a result, acid-modified polyethylene, ethylene-vinyl alcohol copolymer, polyvinyl alcohol, or two or more kinds of these resins (sealing resin) are used as the resin contained in the sealing portion, and the molecular chains of these sealing resins are used. It has been found that even when the thickness of the sealing portion is reduced by sufficiently increasing the degree of orientation, a photoelectric conversion element having sufficiently excellent adhesion of the sealing portion to the electrode substrate or the counter substrate can be realized. Here, the degree of orientation of the molecular chain of the sealing resin can be evaluated based on X-ray diffraction, microscopic Raman scattering measurement, etc., but errors in the degree of orientation can be reduced and the sealing resin is not sufficiently crystallized. Since the degree of orientation can be sufficiently evaluated, the present inventors considered that it is effective to evaluate the degree of orientation of the molecular chain of the sealing resin based on microscopic Raman scattering measurement. Here, the orientation degree of the molecular chain of the sealing resin based on the microscopic Raman scattering measurement can be evaluated as follows. First, the sealing resin, in the Raman spectrum obtained by Raman scattering measurement, the Raman shift and the area of 2845～2851Cm ^-1 Raman shift peaks are observed in the respective areas of 2879~2885cm ^-1. Among these, the peak in the region where the Raman shift is 2845 to 2851 cm ⁻¹ corresponds to a so-called Gauche type molecular chain, and the peak intensity I ₁ is influenced by the number of Gauche type molecular chains. On the other hand, the peak in the region where the Raman shift is 2879 to 2885 cm ⁻¹ corresponds to the trans-type molecular chain, and the peak intensity I ₂ is influenced by the number of trans-type molecular chains. Therefore, the degree of orientation of the molecular chains of the sealing resin contained in the sealing portion can be evaluated by the ratio _{R (= I 2 / I 1} ) of _{I 2} for the _{I 1.} In order to realize a photoelectric conversion element in which the adhesion of the sealing part to the electrode substrate or the counter substrate is sufficiently excellent even if the thickness of the sealing part is small, the inventors have compared the peak intensity ratio. It has been found that R must be greater than a specific value. Thus, the inventors have completed the present invention.

That is, the present invention includes at least one photoelectric conversion cell, and the photoelectric conversion cell joins the electrode substrate, the counter substrate facing the electrode substrate, the electrode substrate and the counter substrate, and the electrode substrate and An annular sealing portion provided between the counter substrates, the sealing portion including at least one selected from the group consisting of acid-modified polyethylene, ethylene-vinyl alcohol copolymer and polyvinyl alcohol, In the Raman spectrum obtained by performing microscopic Raman scattering measurement on the sealing portion, the sealing portion has a thickness of 50 μm or less, and the peak intensity in a region where the Raman shift is 2845 to 2851 cm ⁻¹ is I ₁ , If the Raman shift peak intensity in the region of 2879～2885Cm ^-1 was _{I 2,} R represented by the following formula (1) Value is 1.15 or more, which is a photoelectric conversion element.

R = I ₂ / I ₁ (1)

  According to this photoelectric conversion element, by setting the thickness of the sealing portion to 50 μm or less, the moisture transmission cross-sectional area in the sealing portion can be sufficiently reduced. For this reason, according to the photoelectric conversion element of this invention, it becomes possible to fully suppress the penetration | invasion of the water | moisture content to cell space, and it becomes possible to have the outstanding durability also in a high-humidity environment.

  Moreover, according to the photoelectric conversion element of this invention, when a sealing part contains at least 1 sort (s) chosen from the group which consists of acid-modified polyethylene, an ethylene-vinyl alcohol copolymer, and polyvinyl alcohol, said Formula (1) When the value of R represented by is set to 1.15 or more, the sealing portion can have excellent adhesion to the electrode substrate and the counter substrate. Therefore, the photoelectric conversion element is placed in a heat cycle environment, and excessive stress is applied to the interface between the electrode substrate and the sealing portion and the interface between the counter substrate and the sealing portion in the photoelectric conversion cell. Even in this case, according to the photoelectric conversion element of the present invention, peeling of the sealing portion from the electrode substrate or the counter substrate can be sufficiently suppressed. Therefore, the photoelectric conversion element of the present invention can have excellent durability even in a heat cycle environment.

  As described above, the photoelectric conversion element of the present invention can have excellent durability in both a heat cycle environment and a high humidity environment.

  When the sealing part contains at least one selected from the group consisting of acid-modified polyethylene, ethylene-vinyl alcohol copolymer and polyvinyl alcohol, the value of R represented by the above formula (1) is 1.15. In the case described above, the reason why the sealing portion can have excellent adhesion to the electrode substrate and the counter substrate is not clear, but the present inventors presume that it is as follows. ing.

That is, when the sealing portion contains at least one selected from the group consisting of acid-modified polyethylene, ethylene-vinyl alcohol copolymer and polyvinyl alcohol, the value of R represented by the above formula (1) is 1.15. In the case above, the value of I ₂ is sufficiently larger than the value of I ₁ . That is, when the value of R is 1.15 or more, the number of trans-type molecular chains is larger than the number of Gauche-type molecular chains. Here, the trans-type molecular chain is in an extended state as compared with the Gauche-type molecular chain. For this reason, the trans-type molecular chain is closer to the surface of the electrode substrate and the surface of the counter substrate than the Gauche-type molecular chain, and has a larger intermolecular force on the surface of the electrode substrate and the surface of the counter substrate. It is thought that it has. For this reason, the present inventors speculate that the sealing portion may have excellent adhesion to the electrode substrate and the counter substrate.

  In the said photoelectric conversion element, it is preferable that the thickness of the said sealing part is 10 micrometers or more.

  In this case, compared with the case where the thickness of the sealing part is less than 10 μm, the adhesion of the sealing part to the electrode substrate or the counter substrate is further improved. For this reason, it becomes possible for the photoelectric conversion element to have more excellent durability in both a heat cycle environment and a high humidity environment.

In the present invention, the Raman spectrum obtained by performing the microscopic Raman scattering measurement on the sealing portion is measured using the microscopic Raman spectrophotometer (product name “HoloLab SERIES 5000”, manufactured by Kaiser Optical Systems Co., Ltd.). It shall mean a Raman spectrum obtained by performing microscopic Raman scattering measurement under conditions.
(Measurement condition)
Exposure time: 20 seconds Excitation wavelength: 532 nm
Magnification of objective lens: 100 times Numerical aperture of objective lens: 0.95
Number of exposures (integrations): 3 times Measurement temperature: 25 ° C

  ADVANTAGE OF THE INVENTION According to this invention, the photoelectric conversion element which has the outstanding durability in any of a heat cycle environment and a high-humidity environment is provided.

It is a cut surface end view showing one embodiment of a photoelectric conversion element of the present invention. It is a graph which shows the result of the Raman spectrum obtained by performing micro Raman scattering measurement about the oriented resin film of manufacture example 1.

  Hereinafter, an embodiment of the photoelectric conversion element of the present invention will be described in detail with reference to FIG. FIG. 1 is a cross-sectional end view showing an embodiment of the photoelectric conversion element of the present invention.

  As shown in FIG. 1, the photoelectric conversion element 100 includes one photoelectric conversion cell 60. The photoelectric conversion cell 60 includes an electrode substrate 10, a counter substrate 20 facing the electrode substrate 10, and the electrode substrate 10 and the counter substrate 20 bonded together, and an annular sealing portion provided between the electrode substrate 10 and the counter substrate 20. 30, an electrolyte 40 disposed in a cell space formed by the electrode substrate 10, the counter substrate 20, and the sealing portion 30, and an oxide semiconductor layer 50 provided on the surface of the electrode substrate 10 on the counter substrate 20 side. And a dye (not shown) supported on the oxide semiconductor layer 50.

  The electrode substrate 10 includes a transparent substrate 11 and a transparent conductive layer 12 provided on the transparent substrate 11.

  In the present embodiment, the counter substrate 20 is configured as a counter electrode, and includes a conductive substrate 21 serving as a substrate and an electrode, and a catalyst layer 22 provided on the conductive substrate 21. The catalyst layer 22 is provided on the electrode substrate 10 side of the conductive substrate 21.

  The sealing unit 30 includes at least one selected from the group consisting of acid-modified polyethylene, ethylene-vinyl alcohol copolymer, and polyvinyl alcohol. The thickness of the sealing part 30 is 50 μm or less.

Moreover, in the sealing part 30, in the Raman spectrum obtained by performing micro Raman scattering measurement about the sealing part 30, the peak intensity in a region where the Raman shift is 2845 to 2851 cm ⁻¹ is I ₁ , and the Raman shift is 2879 to When the peak intensity in the region of 2885 cm ⁻¹ is I ₂ , the value of R represented by the following formula (1) is 1.15 or more.

R = I ₂ / I ₁ (1)

  According to the photoelectric conversion element 100, by setting the thickness of the sealing portion 30 to 50 μm or less, the moisture transmission cross-sectional area in the sealing portion 30 can be sufficiently reduced. For this reason, according to the photoelectric conversion element 100, it is possible to sufficiently suppress the intrusion of moisture into the cell space, and it is possible to have excellent durability even in a high humidity environment.

  Moreover, according to the photoelectric conversion element 100, when the sealing part 30 contains at least 1 sort (s) chosen from the group which consists of acid-modified polyethylene, an ethylene-vinyl alcohol copolymer, and polyvinyl alcohol, it represents with said Formula (1). By setting the value of R to be 1.15 or more, the sealing portion 30 can have excellent adhesion to the electrode substrate 10 and the counter substrate 20. For this reason, the photoelectric conversion element 100 is placed in a heat cycle environment, and the interface between the electrode substrate 10 and the sealing portion 30 and the interface between the counter substrate 20 and the sealing portion 30 in the photoelectric conversion cell 60. Even when excessive stress is applied to the substrate, according to the photoelectric conversion element 100, it is possible to sufficiently suppress the peeling of the sealing portion 30 from the electrode substrate 10 or the counter substrate 20. Therefore, the photoelectric conversion element 100 can have excellent durability even in a heat cycle environment.

  As described above, the photoelectric conversion element 100 can have excellent durability in both a heat cycle environment and a high humidity environment.

  Next, the electrode substrate 10, the counter substrate 20, the sealing portion 30, the electrolyte 40, the oxide semiconductor layer 50, and the dye will be described in detail.

≪Electrode substrate≫
As described above, the electrode substrate 10 includes the transparent substrate 11 and the transparent conductive layer 12 provided on the transparent substrate 11.

<Transparent substrate>
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 photoelectric conversion element 100 and is not particularly limited, but may be in a range of 0.05 to 40 mm, for example.

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

≪Counter substrate≫
As described above, the counter substrate 20 includes the conductive substrate 21 serving as a substrate and an electrode, and the catalyst layer 22 provided on the electrode substrate 10 side of the conductive substrate 21 to promote the catalytic reaction.

<Conductive substrate>
The conductive substrate 21 is made of a corrosion-resistant metal material such as titanium, nickel, platinum, molybdenum, tungsten, aluminum, and stainless steel. The conductive substrate 21 may be formed of a laminate in which a substrate and an electrode are separated and a conductive layer made of a conductive oxide such as ITO or FTO is formed on a resin film as an electrode. A laminate in which a conductive layer made of a conductive oxide such as FTO is formed may be used. The thickness of the conductive substrate 21 is appropriately determined according to the size of the photoelectric conversion element 100 and is not particularly limited, but may be, for example, 0.01 to 0.1 mm.

<Catalyst layer>
The catalyst layer 22 is made of a metal such as platinum, a carbon-based material, or a conductive polymer.

≪Sealing part≫
The sealing unit 30 includes at least one selected from the group consisting of acid-modified polyethylene, ethylene-vinyl alcohol copolymer, and polyvinyl alcohol.

  Of these, acid-modified polyethylene is preferred. In this case, the sealing property of the sealing part 30 is increased, and the sealed electrolyte 40 is hardly deteriorated.

  Examples of the acid-modified polyethylene include maleic anhydride-modified polyethylene and acrylic acid-modified polyethylene.

  In the sealing part 30, the value of R represented by the above formula (1) is not particularly limited as long as it is 1.15 or more, but the value of R is more preferably 1.17 or more. . In this case, the adhesion of the sealing portion 30 to the electrode substrate 10 and the counter substrate 20 is further improved. However, the value of R is preferably 1.30 or less. Compared with the case where the value of R exceeds 1.30, the melting point of the sealing material is less likely to increase, and the sealing performance is less likely to be lowered. The value of R is more preferably 1.25 or less.

The Raman shift of the peak corresponding to the Gauche type is observed in the region of 2845 to 2851 cm ⁻¹ , but is usually observed at 2848 cm ⁻¹ . On the other hand, the Raman shift of the peak corresponding to the transformer type is observed in the region from 2879 to 2885 cm ⁻¹ , but is usually observed at 2882 cm ⁻¹ .

  The molecular orientation direction in the sealing portion 30 is not particularly limited, but is preferably a direction parallel to the surface of the transparent substrate 11 on the transparent conductive layer 12 side. In this case, the trans-type molecular chain in the sealing part 30 can easily approach the surfaces of the electrode substrate 10 and the counter substrate 20, and the adhesion of the sealing part 30 to the electrode substrate 10 and the counter substrate 20 is further improved.

  The thickness of the sealing part 30 is not particularly limited as long as it is 50 μm or less, but the thickness of the sealing part 30 is preferably 45 μm or less. In this case, the penetration | invasion of the water | moisture content in the cell space in the photoelectric conversion cell 60 can be suppressed more fully. The thickness of the sealing part 30 is more preferably 40 μm or less.

  However, the thickness of the sealing portion 30 is preferably 10 μm or more. In this case, compared with the case where the thickness of the sealing part 30 is less than 10 μm, the adhesiveness of the sealing part 30 to the electrode substrate 10 or the counter substrate 20 is further improved. For this reason, it becomes possible for the photoelectric conversion element 100 to have more excellent durability in both a heat cycle environment and a high humidity environment. The thickness of the sealing part 30 is more preferably 15 μm or more.

≪Electrolyte≫
The electrolyte 40 includes a redox couple and an organic solvent. As the organic solvent, acetonitrile, methoxyacetonitrile, methoxypropionitrile, propionitrile, ethylene carbonate, propylene carbonate, diethyl carbonate, γ-butyrolactone, valeronitrile, pivalonitrile, and the like can be used. Examples of the redox pair include a redox pair containing a halogen atom such as iodide ion / polyiodide ion (for example, I ⁻ / I ₃ ⁻ ), bromide ion / polybromide ion, zinc complex, iron complex, cobalt complex, and the like. And redox pairs. The iodide ion / polyiodide ion can be formed by iodine (I ₂ ) and a salt (ionic liquid or solid salt) containing iodide (I ⁻ ) as an anion. When using an ionic liquid having an iodide as an anion, only iodine should be added. When using an ionic liquid other than an organic solvent or an anion as an anion, an anion such as LiI or tetrabutylammonium iodide is used. A salt containing iodide (I ⁻ ) may be added. The electrolyte 40 may use an ionic liquid instead of the organic solvent. As the ionic liquid, for example, known iodine salts such as pyridinium salts, imidazolium salts, triazolium salts, and the like are used. Examples of such iodine salts include 1-hexyl-3-methylimidazolium iodide, 1-ethyl-3-propylimidazolium iodide, 1-ethyl-3-methylimidazolium iodide, 1,2- Dimethyl-3-propylimidazolium iodide, 1-butyl-3-methylimidazolium iodide, or 1-methyl-3-propylimidazolium 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. Examples of the additive include benzimidazoles such as 1-methylbenzimidazole (NMB) and 1-butylbenzimidazole (NBB), LiI, tetrabutylammonium iodide, 4-t-butylpyridine, and guanidinium thiocyanate. . Among them, benzimidazole is preferable as an additive.

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.

≪Oxide semiconductor layer≫
The oxide semiconductor layer 50 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 50 may be 0.1 to 100 μm, for example.

  The oxide semiconductor layer 50 is generally composed of an absorption layer for absorbing light, but may be composed of an absorption layer and a reflective layer that reflects light transmitted through the absorption layer and returns it to the absorption layer.

≪Dye≫
Examples of the dye include a ruthenium complex having a ligand including a bipyridine structure, a terpyridine structure, and the like, a photosensitizing dye such as an organic dye such as porphyrin, eosin, rhodamine, and merocyanine, and an organic substance such as a lead halide perovskite crystal. -An inorganic composite pigment | dye etc. are mentioned. For example, CH ₃ NH ₃ PbX ₃ (X = Cl, Br, I) is used as the lead halide perovskite. Among the above dyes, a ruthenium complex having a ligand containing a bipyridine structure or a terpyridine structure is preferable. In this case, the photoelectric conversion characteristics of the photoelectric conversion element 100 can be further improved. In addition, when using a photosensitizing dye as a pigment | dye, the photoelectric conversion element 100 turns into a dye-sensitized photoelectric conversion element.

  Next, an example of a method for manufacturing the photoelectric conversion element 100 will be described.

  First, an electrode substrate 10 formed by forming a transparent conductive layer 12 on one transparent substrate 11 is prepared.

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

  Next, a precursor of the oxide semiconductor layer 50 is formed on the transparent conductive layer 12.

  The precursor of the oxide semiconductor layer 50 can be formed by printing an oxide semiconductor layer forming paste containing oxide semiconductor particles and then drying the paste.

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

  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.

  Then, the precursor of the oxide semiconductor layer 50 is fired to form the oxide semiconductor layer 50.

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

  Thus, the electrode substrate 10 on which the oxide semiconductor layer 50 is formed is obtained.

  Next, an annular sealing portion forming body for forming the sealing portion 30 is formed on the electrode substrate 10.

  Here, the sealing part forming body can be formed on the electrode substrate 10 as follows, for example.

  That is, first, a sealing part forming film composed of a laminate of a carrier film and an alignment resin film containing a sealing resin as a material of the sealing part forming body is prepared, It can be obtained by forming an opening in the oriented resin film, adhering the oriented resin film to the electrode substrate 10 by heating and melting, and then peeling the carrier film.

  At this time, as the carrier film, a film having a higher melting point than the resin film, such as a PET (polyethylene terephthalate) film, is used.

  As the oriented resin film, a resin film having an R value represented by the above formula (1) of 1.15 or more is used. An oriented resin film having an R value of 1.15 or more can be obtained, for example, using an inflation method. Specifically, the resin film having an R value of 1.15 or more has a ratio (blow-up rate) of the maximum diameter of the bag-like film extruded from the extruder to the inner diameter of the circular die of the extruder in the inflation method. For example, it can obtain by setting it as 1.4-2.9.

  Next, a dye is supported on the oxide semiconductor layer 50 of the electrode substrate 10. For this purpose, for example, the electrode substrate 10 is immersed in a solution containing a dye, the dye is adsorbed on the oxide semiconductor layer 50, and then the excess dye is washed away with the solvent component of the solution and dried. That's fine.

  Next, the electrolyte 40 is prepared. And the electrolyte 40 is arrange | positioned inside the cyclic | annular sealing part formation body fixed on the electrode substrate 10. FIG. Thus, the structure A is obtained.

  On the other hand, the counter substrate 20 is prepared.

  The counter substrate 20 can be obtained by forming the conductive catalyst layer 22 on the conductive substrate 21 as described above.

  Then, the structure A and the counter substrate 20 are overlapped with the sealing portion forming body sandwiched between the electrode substrate 10 and the counter substrate 20, and the sealing portion forming body is interposed via the electrode substrate 10 and the counter substrate 20. Is heated and melted under pressure. Thus, an annular sealing portion 30 that joins the electrode substrate 10 and the counter substrate 20 is formed between the electrode substrate 10 and the counter substrate 20.

  The photoelectric conversion element 100 is obtained as described above.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the photoelectric conversion element 100 is configured by one photoelectric conversion cell 60, but the photoelectric conversion element 100 may include a plurality of photoelectric conversion cells 60.

  Further, in the above embodiment, the counter electrode constitutes the counter substrate 20, but an insulating substrate may be used as the counter substrate 20 instead of the counter electrode. In this case, the counter electrode is provided between the electrode substrate 10 and the counter substrate 20, and the oxide semiconductor layer 50 is provided between the counter electrode and the electrode substrate 10.

  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.

(Production Example 1)
A sealing portion forming film was prepared as follows.

  First, pellets made of acid-modified polyethylene (trade name “Binell”, manufactured by DuPont) were prepared.

  Next, the pellets were put into an extruder and continuously extruded as a bag-like film. At this time, extrusion was performed while inflating the bag-like film with pressurized air. At this time, the blow-up rate of the extruder (ratio of the maximum diameter of the bag-like film extruded from the circular die to the inner diameter of the circular die of the extruder) was set to 2.4.

  The bag-like film was sandwiched between a pair of nip rolls to form a sheet, and then wound around a roll while being cut into two sheets. Thus, an oriented resin film having a thickness of 35 μm was obtained.

At this time, the obtained oriented resin film was subjected to microscopic Raman scattering measurement using a microscopic Raman spectrophotometer (product name “HoloLab SERIES 5000”, manufactured by Kaiser Optical Systems) to obtain a Raman spectrum. The results are shown in FIG. In the Raman spectrum shown in FIG. 2, the peak intensity Raman shift in the region of 2845~2851cm ^-1 _{(I 1)} and Raman shift using a peak intensity _{(I 2)} in the region of 2879～2885Cm ^-1, the following equation (1 ) To calculate the peak intensity ratio R. The results are shown in Table 1.

R = I ₂ / I ₁ (1)

The measurement conditions for the microscopic Raman scattering measurement were as follows.
<Measurement conditions for micro Raman scattering measurement>
Exposure time: 20 seconds Excitation wavelength: 532 nm
Magnification of objective lens: 100 times Numerical aperture of objective lens: 0.95
Number of exposures (integrations): 3 times Measurement temperature: 25 ° C

  Finally, the orientation resin film wound around the roll and the PET film wound around the roll were heated and sandwiched between a rubber roll and a metal roll, and heat-laminated (roll laminated), and then wound onto the roll. . Thermal lamination was performed under conditions of 75 ° C. and 0.4 MPa. In this way, the sealing part forming film was obtained.

(Production Examples 2-9)
A film for forming a sealing portion was produced in the same manner as in Production Example 1 except that the blow-up rate when forming the bag-like film using an extruder was set to the values shown in Table 1. At this time, the peak intensity ratio R was calculated in the same manner as in Production Example 1 for the oriented resin film obtained during the production of the sealing portion forming film. The results are shown in Table 1.

Example 1
First, an electrode substrate was prepared by forming a transparent conductive layer made of FTO having a thickness of 0.7 μm on a 112 mm × 56 mm × 2.2 mm transparent substrate made of glass.

  Next, the precursor of the oxide semiconductor layer was formed on the transparent conductive layer of the electrode substrate. Specifically, first, an oxide semiconductor layer forming paste (trade name “PST-21NR”, manufactured by JGC Catalysts & Chemicals Co., Ltd.) is 102.1 mm × 47.2 mm × 12 μm on the transparent conductive layer by screen printing. It was printed in a rectangular shape and dried to form an oxide semiconductor layer precursor.

  Next, the precursor of the oxide semiconductor layer was baked at 500 ° C. for 30 minutes to form an oxide semiconductor layer on the transparent conductive layer. Thus, an electrode substrate on which the oxide semiconductor layer was formed was obtained.

  Next, the sealing part forming film obtained in Production Example 1 was prepared, and one opening of 102.1 mm × 47.2 mm was formed only in the oriented resin film of the sealing part forming film.

  Next, after placing the oriented resin film with the opening formed on the electrode substrate without peeling off the PET film, the oriented resin film was melted and bonded to the electrode substrate by hot pressing at 205 ° C. Thereafter, the PET film was peeled off. In this way, a sealing portion forming body was formed on the electrode substrate.

  Next, the dye substrate was adsorbed on the oxide semiconductor layer by immersing the electrode substrate on which the sealing portion forming body was formed in the dye solution for one day. At this time, as the dye solution, a dye solution in which 0.2 mM Z907 dye was dissolved in a mixed solvent obtained by mixing acetonitrile and tert-butanol at a volume ratio of 1: 1 was used.

Next, an electrolyte was disposed inside the sealed portion forming body. As an electrolyte, 1-hexyl-3-methylimidazolium iodide 2M, I ₂ 0.002M, n-methylbenzimidazole 0.3M, and guanidine thiocyanate 0.1M were added in a solvent composed of 3-methoxypropionitrile. What was dissolved was used. Thus, Structure A was obtained.

  Next, a counter substrate was prepared by forming a catalyst layer made of platinum having a thickness of 5 nm on a titanium foil of 106.1 mm × 51.2 mm × 40 μm by sputtering.

  Next, after placing the oriented resin film in which the opening is formed on the titanium foil without peeling off the PET film, the oriented resin film is melted and adhered to the titanium foil by heating to 150 ° C. under reduced pressure. It was. Thereafter, the PET film was peeled off. In this way, a sealing portion forming body was formed on the counter substrate.

  Then, the structure A and the counter substrate were superposed in a vacuum chamber having a vacuum degree of 600 Pa, and the sealing portion forming body was heated and melted while being pressed through the electrode substrate and the counter substrate. Thus, the electrode substrate and the counter substrate were bonded to obtain an annular sealing portion having a thickness of 50 μm. At this time, pressurization of the sealing portion forming body was performed at a press pressure of 0.1 MPa, and heating was performed at 150 ° C.

  As described above, a photoelectric conversion element including one photoelectric conversion cell was produced.

(Examples 2-5 and Comparative Examples 1-8)
Except that the sealing part forming body was formed on the electrode substrate using the sealing part forming film shown in Table 2, and the thickness of the sealing part and the peak intensity ratio R were as shown in Table 2. In the same manner as in Example 1, a photoelectric conversion element was produced.

≪Characteristic evaluation≫
(1) Durability evaluation under high-humidity environment The photoelectric conversion elements of Examples 1 to 5 and Comparative Examples 1 to 8 obtained as described above were subjected to a high-temperature and high-humidity test. Durability under high humidity environment was evaluated based on the output residual rate. Specifically, with respect to the photoelectric conversion elements of Examples 1 to 5 and Comparative Examples 1 to 8, an IV curve was measured in a state in which 200 lux of white light was irradiated immediately after production, and the maximum output calculated from this IV curve. The operating power Pm ₀ (μW) was calculated. The light source, illuminance meter, and power source used for measuring the IV curve are as follows.

Light source: White LED (product name “LEL-SL5N-F”, manufactured by Toshiba Lighting & Technology Corp.)
Illuminance meter: Product name “Digital Illuminance Meter 51013”, Yokogawa Meter & Instruments Power Supply: Voltage / Current Generator (Product name “R6246I”, ADVANTEST)

The photoelectric conversion element was placed in a constant temperature bath (product name “Humilab”, manufactured by GE) at 85 ° C. and 85% relative humidity under irradiation of a fluorescent lamp of 500 lux for 1000 hours, and then taken out. The IV curve was measured in a state where the above white light of 200 lux was irradiated again, and the maximum output operating power PW (μW) calculated from the IV curve was calculated. And the maximum output residual rate was computed based on the following formula. The results are shown in Table 2.

Maximum output remaining rate (%) = 100 × PW / Pm ₀

The acceptance criteria for durability in a high humidity environment were as follows.

(Acceptance criteria) Maximum output residual rate by high temperature and high humidity test is 80% or more

(2) Evaluation of durability under heat cycle environment About the photoelectric conversion elements of Examples 1 to 5 and Comparative Examples 1 to 8 obtained as described above, a heat cycle test is performed, and an output remaining ratio by the heat cycle test is obtained. Based on this, durability under a heat cycle environment was evaluated. Specifically, for the photoelectric conversion elements of Examples 1 to 5 and Comparative Examples 1 to 8, before and after the heat cycle test, the white LED was used as a light source, and the IV curve was used with the illuminance meter under an illuminance of 200 lux. The output (μW) was calculated from the IV curve. And the output residual rate was computed based on the following formula. The results are shown in Table 2.

Output residual ratio (%) = 100 × output after heat cycle test / output before heat cycle test

At this time, according to JIS C8917, the heat cycle test was performed 200 cycles by setting the temperature to -40 ° C and then increasing the temperature to 90 ° C as one cycle.

Moreover, the acceptance criteria for durability in a heat cycle environment were as follows.

(Acceptance criteria) Residual output rate by heat cycle test is 80% or more

  From the results shown in Table 2, the photoelectric conversion elements of Examples 1 to 5 satisfied the acceptance criteria for both durability under a high humidity environment and durability under a heat cycle environment. On the other hand, the photoelectric conversion elements of Comparative Examples 1 to 8 did not satisfy the acceptance criteria for either durability under a high humidity environment or durability under a heat cycle environment.

  From the above, it was confirmed that the photoelectric conversion element of the present invention can have excellent durability in both a heat cycle environment and a high humidity environment.

DESCRIPTION OF SYMBOLS 10 ... Electrode substrate 20 ... Opposite substrate 30 ... Sealing part 60 ... Photoelectric conversion cell 100 ... Photoelectric conversion element

Claims (2)

Comprising at least one photoelectric conversion cell;
The photoelectric conversion cell is
An electrode substrate;
A counter substrate facing the electrode substrate;
Bonding the electrode substrate and the counter substrate, and having an annular sealing portion provided between the electrode substrate and the counter substrate,
The sealing part includes at least one selected from the group consisting of acid-modified polyethylene, ethylene-vinyl alcohol copolymer and polyvinyl alcohol,
The sealing portion has a thickness of 50 μm or less,
In the Raman spectrum obtained by performing microscopic Raman scattering measurement on the sealing portion, the peak intensity in the region where the Raman shift is 2845 to 2851 cm ⁻¹ is I ₁ and the peak intensity in the region where the Raman shift is 2879 to 2885 cm ^−1. Is a photoelectric conversion element in which the value of R represented by the following formula (1) is 1.15 or more when I ₂ is I ₂ .

R = I ₂ / I ₁ (1)
  The photoelectric conversion element of Claim 1 whose thickness of the said sealing part is 10 micrometers or more.

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