JP6818396B2 - Photoelectric conversion element - Google Patents

Description

The present invention relates to a photoelectric conversion element.

As a photoelectric conversion element, a photoelectric conversion element using a dye has attracted attention because it is inexpensive and high photoelectric conversion efficiency can be obtained, and various developments have been made on the photoelectric conversion element using a dye.

As a photoelectric conversion element using a dye, for example, the photoelectric conversion element described in Patent Document 1 below is known. In Patent Document 1 below, the photoelectric conversion element includes at least one photoelectric conversion cell, and the photoelectric conversion cell is an annular shape that joins the electrode substrate, the opposing substrate facing the electrode substrate, and the electrode substrate and the opposing substrate. It is disclosed to have a sealing portion. Patent Document 1 also discloses that the sealing portion is composed of a modified polyolefin resin, a vinyl alcohol polymer, or the like.

Japanese Unexamined Patent Publication No. 2016-207949

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 of the present invention is to provide a photoelectric conversion element having excellent durability in both a heat cycle environment and a high humidity environment.

The present inventors have investigated the causes of the above problems. As a result, in the photoelectric conversion element described in Patent Document 1, by reducing the thickness of the sealing portion to 50 μm or less, the cross-sectional area through which moisture passes in the sealing portion can be reduced, and in a high humidity environment. I thought that it might be possible to improve the durability of the. However, if the thickness of the sealing portion is made too small, the adhesiveness of the sealing portion to the electrode substrate or the facing substrate is lowered, and the sealing portion is easily peeled off from the electrode substrate or the facing substrate, resulting in a heat cycle environment. Durability is reduced. Therefore, 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 a photoelectric conversion element having sufficiently excellent adhesiveness of the sealing portion to the electrode substrate or the opposing substrate can be realized even when the thickness of the sealing portion is reduced by sufficiently increasing the degree of orientation. Here, the degree of orientation of the molecular chain of the sealing resin can be evaluated based on X-ray diffraction, micro-Raman scattering measurement, etc., but the error in the degree of orientation can be reduced, and even if 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 the microscopic Raman scattering measurement. Here, the degree of orientation of the molecular chains of the sealing resin based on the micro-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. Of these, the peak in the region where the Raman shift is 2845 to 2851 cm ^-1 corresponds to the so-called gauche type molecular chain, and its 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.} Then, in order to realize a photoelectric conversion element having sufficiently excellent adhesiveness of the sealing portion to the electrode substrate or the opposing substrate even if the thickness of the sealing portion is small, the present inventors have a ratio of the peak intensities. We have found that R needs to be greater than or equal to a certain value. In this way, the present 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 opposing substrate facing the electrode substrate, the electrode substrate, and the opposing substrate, and the electrode substrate and the opposed substrate. It has an annular sealing portion provided between the opposing substrates, and the sealing portion contains 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 microscopic Raman scattering measurement of the sealing portion when the thickness of the sealing portion is 50 μm or less, the peak intensity in the region where the Raman shift is 2845 to 2851 cm ^-1 is defined as I ₁ . When the peak intensity in the region where the Raman shift is 2879 to 2885 cm ^-1 is I ₂ , the value of R represented by the following formula (1) 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 permeation cross-sectional area of water in the sealing portion can be sufficiently reduced. Therefore, according to the photoelectric conversion element of the present invention, it is possible to sufficiently suppress the invasion of water into the cell space, and it is possible to have excellent durability even in a high humidity environment.

Further, according to the photoelectric conversion element of the present invention, 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 above formula (1) By setting the value of R represented by (1) to 1.15 or more, the sealing portion can have excellent adhesiveness to the electrode substrate and the opposing 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 opposing substrate and the sealing portion in the photoelectric conversion cell. Even in this case, according to the photoelectric conversion element of the present invention, it is possible to sufficiently suppress the peeling of the sealing portion from the electrode substrate or the facing substrate. Therefore, the photoelectric conversion element of the present invention can have excellent durability even in a heat cycle environment.

From the 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 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 above case, the reason why the sealing portion can have excellent adhesiveness to the electrode substrate and the opposing 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 above case, 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 a stretched state as compared with the gauche-type molecular chain. Therefore, the trans-type molecular chain is easier to approach the surface of the electrode substrate and the surface of the opposing substrate than the gauche-type molecular chain, and has a larger intermolecular force with respect to the surface of the electrode substrate and the surface of the opposing substrate. Is considered to have. Therefore, the present inventors speculate that the sealing portion may have excellent adhesiveness to the electrode substrate and the opposing substrate.

In the photoelectric conversion element, the thickness of the sealing portion is preferably 10 μm or more.

In this case, the adhesiveness of the sealing portion to the electrode substrate or the opposing substrate is further improved as compared with the case where the thickness of the sealing portion is less than 10 μm. Therefore, the photoelectric conversion element can 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 sealed portion is measured by using a microscopic Raman spectrophotometer (product name "HoloLab SERIES 5000", manufactured by Kaiser Optical Systems Co., Ltd.) as follows. It refers to a Raman spectrum obtained by performing microscopic Raman scattering measurement under conditions.
(Measurement condition)
Exposure time: 20 seconds Excitation wavelength: 532 nm
Objective lens magnification: 100x Objective lens numerical aperture: 0.95
Number of exposures (number of integrations): 3 times Measurement temperature: 25 ° C

According to the present invention, there is provided a photoelectric conversion element having excellent durability in both a heat cycle environment and a high humidity environment.

It is a cut surface end view which shows one Embodiment of the photoelectric conversion element of this invention. It is a graph which shows the result of the Raman spectrum obtained by performing the micro Raman scattering measurement about the alignment resin film of Production Example 1.

Hereinafter, embodiments of the photoelectric conversion element of the present invention will be described in detail with reference to FIG. FIG. 1 is a cut surface 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 is an annular sealing portion provided between the electrode substrate 10 and the opposing substrate 20 facing the electrode substrate 10 by joining the electrode substrate 10 and the opposing substrate 20 to each other. 30, the electrolyte 40 arranged in the cell space formed by the electrode substrate 10, the opposing substrate 20, and the sealing portion 30, and the oxide semiconductor layer 50 provided on the surface of the electrode substrate 10 on the facing substrate 20 side. , A dye (not shown) supported on the oxide semiconductor layer 50 is provided.

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

In the present embodiment, the opposing substrate 20 is composed of counter electrodes, and has a conductive substrate 21 that also serves 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 portion 30 contains at least one selected from the group consisting of acid-modified polyethylene, ethylene-vinyl alcohol copolymer and polyvinyl alcohol. The thickness of the sealing portion 30 is 50 μm or less.

Further, in the sealing portion 30, in the Raman spectrum obtained by performing a microscopic Raman scattering measurement on the sealing portion 30, the peak intensity in the region where the Raman shift is 2845 to 2851 cm ^-1 is I ₁ , and the Raman shift is 2879 to 2. 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 permeation cross-sectional area of water in the sealing portion 30 can be sufficiently reduced. Therefore, according to the photoelectric conversion element 100, it is possible to sufficiently suppress the invasion of water into the cell space, and it is possible to have excellent durability even in a high humidity environment.

Further, according to the photoelectric conversion element 100, when the sealing portion 30 contains at least one selected from the group consisting of acid-modified polyethylene, ethylene-vinyl alcohol copolymer and polyvinyl alcohol, it is represented by the above formula (1). By setting the value of R to be 1.15 or more, the sealing portion 30 can have excellent adhesiveness to the electrode substrate 10 and the opposing substrate 20. Therefore, the photoelectric conversion element 100 is placed in a heat cycle environment, and in the photoelectric conversion cell 60, the interface between the electrode substrate 10 and the sealing portion 30 and the interface between the opposing substrate 20 and the sealing portion 30. 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 opposing substrate 20 even when an excessive stress is applied to the electrode substrate 10. Therefore, the photoelectric conversion element 100 can have excellent durability even in a heat cycle environment.

From the 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 has a transparent substrate 11 and a transparent conductive layer 12 provided on the transparent substrate 11.

<Transparent substrate>
The material constituting the transparent substrate 11 may be, for example, a transparent material, and such transparent materials include, for example, borosilicate glass, soda lime glass, white plate glass, glass such as quartz glass, and polyethylene terephthalate (PET). , Polyethylene naphthalate (PEN), polycarbonate (PC), polyether sulfone (PES) and the like. 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, for example, in the range of 0.05 to 40 mm.

<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 may be composed of a laminate of a plurality of layers composed 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, for example, in the range of 0.01 to 2 μm.

≪Opposite board≫
As described above, the opposing substrate 20 includes a conductive substrate 21 that also serves as a substrate and an electrode, and a catalyst layer 22 that is provided on the electrode substrate 10 side of the conductive substrate 21 and promotes a 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. Further, the conductive substrate 21 may be composed of a laminate in which the substrate and the electrode are separated and a conductive layer made of a conductive oxide such as ITO or FTO is formed as an electrode on a resin film, and the conductive substrate 21 may be formed of an ITO on glass. , FTO or the like may be a laminate in which a conductive layer made of a conductive oxide is formed. 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, a conductive polymer, or the like.

≪Sealing part≫
The sealing portion 30 contains 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 preferable. In this case, the sealing portion 30 becomes more airtight, and the sealed electrolyte 40 is less likely to be deteriorated.

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

In the sealing portion 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 opposing 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 encapsulant is less likely to rise and the airtightness is less likely to decrease. 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 in the region of 2848 cm ^-1 . On the other hand, the Raman shift of the peak corresponding to the trans type is observed in the region of 2879 to 2885 cm ^-1 , but is usually observed in the region of 2882 cm ^-1 .

The orientation direction of the molecules 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 transformer-type molecular chain in the sealing portion 30 can easily approach the surfaces of the electrode substrate 10 and the opposing substrate 20, and the adhesiveness of the sealing portion 30 to the electrode substrate 10 and the opposing substrate 20 is further improved.

The thickness of the sealing portion 30 is not particularly limited as long as it is 50 μm or less, but the thickness of the sealing portion 30 is preferably 45 μm or less. In this case, the invasion of water into the cell space of the photoelectric conversion cell 60 can be more sufficiently suppressed. The thickness of the sealing portion 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, the adhesiveness of the sealing portion 30 to the electrode substrate 10 or the opposing substrate 20 is further improved as compared with the case where the thickness of the sealing portion 30 is less than 10 μm. Therefore, the photoelectric conversion element 100 can have more excellent durability in both a heat cycle environment and a high humidity environment. The thickness of the sealing portion 30 is more preferably 15 μm or more.

≪Electrolyte≫
The electrolyte 40 contains a redox pair 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 redox pairs containing halogen atoms such as iodide ion / polyiodide ion (for example, I ⁻ / I ₃ ⁻ ) and bromide ion / poly bromide ion, as well as zinc complex, iron complex, and cobalt complex. Redox pairs such as. 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 iodide as an anion, only iodine needs to be added, and when using an organic solvent or an ionic liquid other than iodide as an anion, it is used as an anion such as LiI or tetrabutylammonium iodide. A salt containing iodide (I ⁻ ) may be added. Further, as the electrolyte 40, an ionic liquid may be used instead of the organic solvent. As the ionic liquid, for example, known iodine salts such as pyridinium salt, imidazolium salt, and triazolium salt 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-propyl imidazolium iodide, 1-butyl-3-methyl imidazolium iodide, or 1-methyl-3-propyl imidazolium iodide is preferably used.

Further, as the electrolyte 40, a mixture of the ionic liquid and the organic solvent may be used instead of the organic solvent.

Further, an additive can be added to the electrolyte 40. Examples of the additive include benzimidazole such as 1-methylbenzimidazole (NMB) and 1-butylbenzoimidazole (NBB), LiI, tetrabutylammonium iodide, 4-t-butylpyridine, guanidium thiocyanate and the like. .. Of these, benzimidazole is preferable as an additive.

Further, as the electrolyte 40, a nanocomposite gel electrolyte, which is a pseudo-solid electrolyte obtained by kneading nanoparticles such as SiO ₂ , TiO ₂ and carbon nanotubes with the electrolyte to form a gel, may be used, or polyvinylidene fluoride. , 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. Oxide semiconductor particles include, for example, titanium oxide (TiO ₂ ), zinc oxide (ZnO), tungsten oxide (WO ₃ ), niobium oxide (Nb ₂ O ₅ ), strontium titanate (SrTIO ₃ ), tin oxide (SnO ₂ ). , Indium oxide (In ₃ O ₃ ), Zirconium oxide (ZrO ₂ ), Tallium oxide (Ta ₂ O ₅ ), Lanthanum oxide (La ₂ O ₃ ), Yttrium oxide (Y ₂ O ₃ ), Formium 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 of these. The thickness of the oxide semiconductor layer 50 may be, for example, 0.1 to 100 μm.

The oxide semiconductor layer 50 is usually composed of an absorption layer for absorbing light, but may be composed of an absorption layer and a reflection 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 containing a bipyridine structure and a terpyridine structure, a photosensitizing dye such as an organic dye such as porphyrin, eosin, rhodamine, and merocyanin, and an organic dye such as a lead halide perovskite crystal. -Inorganic composite dyes and the like. As the lead-halogenated perovskite, for example, CH ₃ NH ₃ PbX ₃ (X = Cl, Br, I) is used. 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. When a photosensitizing dye is used as the dye, the photoelectric conversion element 100 becomes a dye-sensitized electrosensitizing conversion element.

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

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

As a method for forming the transparent conductive layer 12, a sputtering method, a thin film 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 a paste for forming an oxide semiconductor layer containing oxide semiconductor particles and then drying the paste.

The paste for forming an oxide semiconductor layer contains, in addition to oxide semiconductor particles, a resin such as polyethylene glycol and a solvent such as telepineol.

As a printing method of 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.

In this way, 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 portion forming body can be formed on the electrode substrate 10 as follows, for example.

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

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

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

Next, the 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. Just do it.

Next, the electrolyte 40 is prepared. Then, the electrolyte 40 is arranged inside the annular sealing portion forming body fixed on the electrode substrate 10. In this way, the structure A is obtained.

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

The opposed 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 facing substrate 20 are overlapped with the sealing portion forming body sandwiched between the electrode substrate 10 and the facing substrate 20, and the sealing portion forming body is interposed via the electrode substrate 10 and the facing substrate 20. Is heated and melted while pressurizing. In this way, an annular sealing portion 30 for joining the electrode substrate 10 and the opposing substrate 20 is formed between the electrode substrate 10 and the opposing substrate 20.

As described above, the photoelectric conversion element 100 can be obtained.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the photoelectric conversion element 100 is composed of 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 electrode 20, but as the counter electrode 20, an insulating substrate may be used 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 in more detail with reference to examples, but the present invention is not limited to the following examples.

(Manufacturing Example 1)
A film for forming a sealing portion was prepared as follows.

First, pellets made of acid-modified polyethylene (trade name "Binel", manufactured by DuPont) were prepared.

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

The bag-shaped film was sandwiched between a pair of nip rolls to form a sheet, and then cut into two pieces and wound on a roll. In this way, an oriented resin film having a thickness of 35 μm was obtained.

At this time, the obtained oriented resin film was subjected to micro Raman scattering measurement using a micro Raman spectrophotometer (product name "HoloLab SERIES 5000", manufactured by Kaiser Optical Systems Co., Ltd.) 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 ), The peak intensity ratio R was calculated. 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 microscopic Raman scattering measurement>
Exposure time: 20 seconds Excitation wavelength: 532 nm
Objective lens magnification: 100x Objective lens numerical aperture: 0.95
Number of exposures (number of integrations): 3 times Measurement temperature: 25 ° C

Finally, the oriented resin film wound on the roll and the PET film wound on the roll were heated while being sandwiched between a rubber roll and a metal roll to be heat-laminated (roll-laminated), and then wound on the roll. .. Thermal laminating was performed under the conditions of 75 ° C. and 0.4 MPa. In this way, a film for forming a sealing portion was obtained.

(Manufacturing 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-shaped film using an extruder was set to the value 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 film for forming the sealing portion. The results are shown in Table 1.

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

Next, a precursor of an oxide semiconductor layer was formed on the transparent conductive layer of the electrode substrate. Specifically, first, a paste for forming an oxide semiconductor layer (trade name "PST-21NR", manufactured by Nikki Catalyst Kasei Co., Ltd.) is applied on a transparent conductive layer by a screen printing method to a size of 102.1 mm × 47.2 mm × 12 μm. It was printed in a rectangular shape and dried to form a precursor of an oxide semiconductor layer.

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

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

Next, the oriented resin film having the openings formed was placed on the electrode substrate without peeling off the PET film, and then the oriented resin film was melted and adhered to the electrode substrate by hot pressing at 205 ° C. Then, the PET film was peeled off. In this way, a sealing portion forming body was formed on the electrode substrate.

Next, the electrode substrate on which the sealing portion forming body was formed was immersed in the dye solution for a whole day and night to adsorb the dye on the oxide semiconductor layer. At this time, as the dye solution, a dye solution in which a dye composed of 0.2 mM Z907 was dissolved in a mixed solvent prepared by mixing acetonitrile and tert-butanol in a volume ratio of 1: 1 was used.

Next, an electrolyte was placed inside the sealing portion forming body. As the electrolyte, 1-hexyl-3-methylimidazolium iodide 2M, I ₂ 0.002M, n-methylbenzimidazole 0.3M, and guanidine thiocyanate 0.1M were added to a solvent composed of 3-methoxypropionitrile. The dissolved one was used. In this way, the 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 having a thickness of 106.1 mm × 51.2 mm × 40 μm by a sputtering method.

Next, the oriented resin film having the openings formed is placed on the titanium foil without peeling off the PET film, and then heated to 150 ° C. under reduced pressure to melt the oriented resin film and adhere it to the titanium foil. It was. Then, the PET film was peeled off. In this way, the sealing portion forming body was formed on the facing substrate.

Then, the structure A and the facing 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 pressurized via the electrode substrate and the facing substrate. In this way, the electrode substrate and the opposing substrate were joined to obtain an annular sealing portion having a thickness of 50 μm. At this time, the pressure of the sealing portion forming body was performed with a press pressure of 0.1 MPa, and heating was performed at 150 ° C.

As described above, a photoelectric conversion element composed of one photoelectric conversion cell was manufactured.

(Examples 2 to 5 and Comparative Examples 1 to 8)
Examples except that the sealing portion forming body was formed on the electrode substrate using the sealing portion forming film shown in Table 2 and the thickness of the sealing portion and the peak intensity ratio R were as shown in Table 2. A photoelectric conversion element was manufactured in the same manner as in 1.

≪Characteristic evaluation≫
(1) Evaluation of Durability in High Humidity Environment The photoelectric conversion elements of Examples 1 to 5 and Comparative Examples 1 to 8 obtained as described above are subjected to a high temperature and high humidity test, and the maximum by the high temperature and high humidity test. Durability in a high humidity environment was evaluated based on the output residual ratio. Specifically, for the photoelectric conversion elements of Examples 1 to 5 and Comparative Examples 1 to 8, the IV curve was measured in a state of irradiating 200 lux of white light immediately after fabrication, and the maximum output calculated from this IV curve was measured. The operating power Pm ₀ (μW) was calculated. The light source, illuminometer, and power supply used to measure the IV curve are as follows.

Light source: White LED (product name "LEL-SL5N-F", manufactured by Toshiba Lighting & Technology Corporation)
Illuminance meter: Product name "Digital illuminance meter 51013", Yokogawa Meter & Instruments Power supply: Voltage / current generator (Product name "R6246I", ADVANTEST)

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

Maximum output residual rate (%) = 100 x PW / Pm ₀

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

(Passing criteria) The maximum output residual rate by the high temperature and high humidity test is 80% or more.

(2) Evaluation of Durability in Heat Cycle Environment The photoelectric conversion elements of Examples 1 to 5 and Comparative Examples 1 to 8 obtained as described above were subjected to a heat cycle test, and the output residual ratio by the heat cycle test was performed. Based on the above, the durability in 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 under an illuminance of 200 lux using the illuminometer. The output (μW) was calculated from the IV curve. Then, the output residual ratio was calculated based on the following formula. The results are shown in Table 2.

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

At this time, the heat cycle test was carried out in accordance with JIS C8917, with 200 cycles including one heat cycle in which the temperature was lowered to −40 ° C. and then raised to 90 ° C.

In addition, the acceptance criteria for durability in a heat cycle environment are as follows.

(Passing criteria) The output residual rate by the 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 the durability in a high humidity environment and the durability in a heat cycle environment. On the other hand, the photoelectric conversion elements of Comparative Examples 1 to 8 did not meet the acceptance criteria for either the durability in a high humidity environment or the durability in 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.

10 ... Electrode substrate 20 ... Opposing substrate 30 ... Sealing part 60 ... Photoelectric conversion cell 100 ... Photoelectric conversion element

Claims (2)

With at least one photoelectric conversion cell
The photoelectric conversion cell
With the electrode substrate
Opposing substrate facing the electrode substrate and
It has an annular sealing portion provided between the electrode substrate and the opposing substrate by joining the electrode substrate and the opposing substrate.
The sealing portion contains at least one selected from the group consisting of acid-modified polyethylene, ethylene-vinyl alcohol copolymer and polyvinyl alcohol.
The thickness of the sealing portion is 50 μm or less.
In the Raman spectrum obtained by performing a 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 I _2, and the value of R represented by the following formula (1) is 1.15 or more, which is a photoelectric conversion element.

R = I ₂ / I ₁ ... (1)
The photoelectric conversion element according to claim 1, wherein the sealing portion has a thickness of 10 μm or more.

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