JP2018088480A - Solar battery, solar battery module, and method of manufacturing solar battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve an output characteristic of a solar battery.SOLUTION: A solar cell module 10 comprises a plurality of solar batteries 40 each of which includes: a transparent substrate 11 in which a transparent conductive film 12 that passes through a light is formed; an electron transport layer 24 provided to the transparent substrate 11 through a ground layer 22; a positive hole transport layer 26 adjacently provided to the electron transport layer 24; and a counter electrode 30 adjacent to the positive hole transport layer 26. In the electron transport layer 24, an additive compound including a quaternary ammonium cation having a hydroxy group and a material constructing the positive hole transport layer 26 (e.g., Cu compound) are filled.SELECTED DRAWING: Figure 1

Description

  The invention disclosed in this specification relates to a solar cell, a solar cell module, and a manufacturing method thereof.

  Conventionally, as this type of solar cell, for example, 1-ethyl-3-methylimidazolium thiocyanate (EMISCN) or 1-propyl-3-methylimidazolium iodide is used for a solar cell having CuI as a hole transport layer. The thing which added (PMII) etc. by the predetermined compounding quantity is proposed (for example, refer patent document 1). In this solar cell, it is possible to suppress the decrease in conversion efficiency and further improve the durability.

JP 2012-204276 A

  However, although the above-described solar cell of Patent Document 1 has improved the reduction in conversion efficiency and improved durability, it is still not sufficient, and further improvements such as the study of new additives have been demanded.

  This invention is made | formed in view of such a subject, and it aims at providing the novel solar cell which can improve output characteristics more, and its manufacturing method.

  As a result of intensive studies to achieve the above-described object, the present inventors have found that the output characteristics of a solar cell can be further improved by adding a compound containing a quaternary ammonium cation having a hydroxyl group. The invention disclosed in the book has been completed.

That is, the solar cell disclosed in this specification is
A photoelectrode having an electron transport layer coated with a light absorbing layer and comprising an additive compound comprising a quaternary ammonium cation having a hydroxyl group;
A solid hole transport layer interposed between the photoelectrode and the counter electrode;
It is equipped with.

  The solar cell module disclosed in this specification includes a plurality of the solar cells described above.

The manufacturing method of the solar cell disclosed in this specification is:
A method for producing a solar cell in which a hole transport layer is interposed between a photoelectrode having an electron transport layer coated with a light absorption layer and a counter electrode disposed so as to face the photoelectrode,
A filling step of filling the electron transport layer with the Cu compound and the additive compound using a solution containing an additive compound containing a quaternary ammonium cation having a hydroxyl group and a Cu compound constituting the hole transport layer. It is a waste.

  The solar cell, the solar cell module, and the method for manufacturing the solar cell can provide a novel one that further improves the output characteristics. The reason why such an effect is obtained is presumed as follows. For example, in this additive compound, a hydroxyl group of a quaternary ammonium cation having a hydroxyl group has excellent affinity with an electron transport layer, while a binding site between a quaternary ammonium cation and an anion has excellent affinity with a hole transport layer. It is guessed. For this reason, it is thought that this additive compound can further improve the filling property of the hole transport layer into the pores of the electron transport layer. Moreover, it is thought that this additive compound can suppress generation | occurrence | production of electron recombination (leakage current) more by interposing between an electron carrying layer and a positive hole transport layer. As a result, it is assumed that the output characteristics of the solar cell can be further improved.

FIG. 3 is a cross-sectional view illustrating an example of a schematic configuration of a solar cell module 10. FIG. 3 is a cross-sectional view illustrating an example of a schematic configuration of a solar cell 40. The examination result of the relative output of the solar cell of Experimental Examples 1-6. The alternating current impedance measurement result at the time of 1000 lux light irradiation of Experimental example 1 and 2. FIG. The FE-SEM image of the cross section of the solar cell of Experimental example 1. The FE-SEM image of the cross section of the solar cell of Experimental Example 2.

  One embodiment of a solar cell module will be described with reference to the drawings. FIG. 1 is a cross-sectional view illustrating an example of a schematic configuration of the solar cell module 10. As shown in FIG. 1, the solar cell module 10 according to this embodiment has a configuration in which a plurality of solar cells 40 (hereinafter also referred to as cells) are sequentially arranged on a light-transmitting conductive substrate 14. These cells are connected in series. In this solar cell module 10, a sealing material 32 is formed so as to fill between the cells, and a flat protective member 34 is formed on the surface of the sealing material 32 on the side opposite to the light-transmitting conductive substrate 14. Has been. The solar cell 40 according to this embodiment includes a light-transmitting conductive substrate 12 having a light-transmitting conductive film 12 formed on the surface of a light-transmitting substrate 11 through which light is transmitted, and a light-transmitting conductive film 12 via a base layer 22. An electron transport layer 24, a hole transport layer 26 provided adjacent to the electron transport layer 24, and a counter electrode 30 provided via the hole transport layer 26 and the separator 29. Yes. The photoelectrode 20 includes a light-transmitting conductive substrate 14, a base layer 22 disposed on a light-transmitting conductive film 12 formed separately on the surface opposite to the light-receiving surface 13 of the light-transmitting substrate 11, and a base layer 22 And an electron transport layer 24 that emits electrons upon receiving light. The surface of the electron transport layer is covered with a light absorption layer that absorbs light. This solar cell 40 is configured as a so-called all solid-state solar cell in which the photoelectrode 20 and the counter electrode 30 are connected via the hole transport layer 26. Thus, the solar cell 40 has a configuration capable of generating power without using an electrolyte such as an organic solvent.

The light-transmitting conductive substrate 14 is composed of the light-transmitting substrate 11 and the light-transmitting conductive film 12, and has a light-transmitting property and conductivity, and is used for silicon solar cells and liquid crystal display panels. can do. Specific examples include fluorine-doped SnO ₂ coated glass, ITO coated glass, ZnO: Al coated glass, and antimony-doped tin oxide (SnO ₂ —Sb). In addition, a light transmissive electrode in which tin oxide or indium oxide is doped with cations or anions having different valences, or a metal electrode having a structure capable of transmitting light, such as a mesh shape or a stripe shape, is provided on a substrate such as a glass substrate. Can also be used. Current collecting electrodes 16 and 17 are provided at both ends of the light transmitting conductive substrate 14 on the light transmitting conductive film 12 side, and electric power generated by the solar cell 40 via the current collecting electrodes 16 and 17 is used. can do.

  Examples of the light transmissive substrate 11 include a light transmissive glass, a light transmissive plastic plate, a light transmissive plastic film, an inorganic light transmissive crystal, and the like. Among these, a light transmissive glass is preferable. The light transmissive substrate 11 may be a light transmissive glass substrate, a glass substrate surface that is appropriately roughened to prevent reflection of light, a ground glass-like translucent glass substrate, or the like. The light transmissive conductive film 12 can be formed, for example, by depositing tin oxide on the light transmissive substrate 11. In particular, if a metal oxide such as tin oxide (FTO) doped with fluorine is used, a suitable light-transmitting conductive film 12 can be formed. The light transmissive conductive film 12 has grooves 18 formed at predetermined intervals, and a plurality of regions of the light transmissive conductive film 12 are separately formed at intervals corresponding to the width of the grooves 18.

  The underlayer 22 is a layer that suppresses or prevents leakage current (reverse electron transfer) from the light-transmitting conductive substrate 14 to the hole transport layer 26. For example, a light-transmitting and conductive material is preferable. In addition, n-type semiconductors such as titanium oxide, zinc oxide, and tin oxide can be used, and among these, titanium oxide is more preferable. This is because titanium oxide suppresses and prevents leakage current and easily allows electrons to flow from the electron transport layer 24 to the light-transmitting conductive substrate 14. The underlayer 22 is preferably made of a denser material than the electron transport layer 24. Note that even if the base layer 22 is not formed, the base layer 22 may be omitted because it functions sufficiently as the solar cell 40.

The electron transport layer 24 may be formed of an n-type semiconductor. As the n-type semiconductor, a metal oxide semiconductor or a metal sulfide semiconductor is suitable. For example, titanium oxide (TiO ₂ ), tin oxide (SnO ₂ ), zinc oxide (ZnO), cadmium sulfide (CdS), sulfide It is preferable that it is at least 1 or more among zinc (ZnS), and among these, porous titanium oxide is more preferable. By thinning these semiconductor materials into a microcrystalline or polycrystalline state, a good porous n-type semiconductor layer can be formed. In particular, the porous titanium oxide layer is suitable as an n-type semiconductor layer included in the photoelectrode 20. The material of the light absorption layer (for example, organic dye) may be adsorbed on the surface of the porous n-type semiconductor to form the light absorption layer. This adsorption can be performed by chemical adsorption or physical adsorption. Specifically, a method in which a porous n-type semiconductor layer is formed on the light-transmitting conductive substrate 14 and then a solution containing the material of the light absorption layer is dropped onto the n-type semiconductor layer and dried, or light absorption For example, the light-transmitting conductive substrate 14 may be dipped in a solution containing the layer material and dried.

  The electron transport layer 24 contains an additive compound containing a quaternary ammonium cation having a hydroxyl group (hereinafter also simply referred to as “additive compound”). In this solar cell 40, it is preferable that the electron transport layer 24 to the hole transport layer 26 contain a Cu compound and an additive compound. That is, the electron transport layer 24 may be filled with a Cu compound that is a material of the hole transport layer 26 and an additive compound. The additive compound containing a quaternary ammonium cation having a hydroxyl group has excellent affinity with the electron transport layer 24, while the bonding site between the quaternary ammonium cation and anion has excellent affinity with the hole transport layer 26. it is conceivable that. It is considered that the filling property of the hole transport layer 26 into the pores of the electron transport layer 24 can be further enhanced by the interposition of such an additive compound containing a quaternary ammonium cation having a hydroxyl group. Further, since the additive compound is interposed between the electron transport layer 24 and the hole transport layer 26, recombination (leakage current) between the electrons injected from the light absorption layer into the electron transport layer 24 and the hole transport layer. It is considered that the occurrence of the occurrence can be further suppressed. Note that this additive compound may be supplied to the electron transport layer 24 together with the Cu compound of the hole transport layer 26. This additive compound may contain a quaternary ammonium cation having a hydroxyl group and a halogen anion. Further, the additive compound may include a quaternary ammonium cation having an alkyl group having 5 or less carbon atoms. The shorter the number of carbon atoms, such as 3 or less carbon atoms, 2 or less carbon atoms, or 1 carbon atom, the alkyl group is more preferable because the affinity with the material constituting the hole transport layer is further improved. The alkyl groups of the quaternary ammonium cation may all be different groups, two or more may be the same group, or all may be the same group. Examples of the alkyl group include a pentyl group (including isopentyl group and neopentyl group), a primary to tertiary butyl group, an ethyl group, and a methyl group. Among these, a tertiary butyl group and a methyl group are preferable, and it is more preferable that all are methyl groups. The additive compound preferably has a structure in which a hydroxyl group is connected to a carbon chain longer than the alkyl group having 5 or less carbon atoms. This carbon chain may be, for example, a straight chain having 6 or less carbon atoms or a branched chain having 6 or less carbon atoms. This hydroxyl group has good affinity with the electron transport layer and is preferably connected to the tip side of the carbon chain. Specifically, the additive compound may be one or more of the compounds represented by the following formulas (1) to (3). That is, the additive compound is a trimethyl-2-hydroxyethylammonium salt which is one or more of choline iodide (melting point 272 ° C.), choline bromide (melting point 298 ° C.) and choline chloride (melting point 302 ° C.). It is good. Of these, choline iodide is preferable in consideration of the material of the hole transport layer (for example, CuI). Further, this additive compound is preferably present in a solid state within the use temperature range of the solar cell, and has a melting point of 40 ° C. or higher, more preferably 50 ° C. or higher, and further preferably 60 ° C. or higher. When the additive compound is present in a solid state, for example, movement and disappearance of the cation are further suppressed, so that a stable effect can be obtained. The melting point of this additive compound is preferably 350 ° C. or less, more preferably 300 ° C. or less, considering the ease of handling.

  This additive compound is included in the photoelectrode in a range (addition amount) of the concentration (M) of the additive compound to the concentration (M) of the compound constituting the hole transport layer in the range of 0.1% to 10%. It is preferable. In this range, the addition effect of the additive compound, for example, solar cell characteristics such as improvement of output characteristics can be further improved. The additive amount is more preferably 0.2% or more, and still more preferably 0.6% or more. In addition, the additive amount of the additive compound is more preferably 9.4% or less, and further preferably 8% or less.

The electron transport layer 24 is covered with a light absorption layer. The light absorbing layer may include one or more light absorbing materials among organic dyes, metal complexes, and organic metal halide compounds. This light absorbing material may be an organic dye. Examples of organic dyes include BODIPY dyes (such as BODIPY-FL), indoline dyes (such as D131, D149, D205, and D358), carbazole dyes (such as MK2), and coumarin dyes (C343, NKX-2587, NKX-). 2677 or the like) or squarylium dye (SQ2 or the like). The organic dye may have an aromatic amine as a donor and a cyanocarboxylic acid anchor group via a π-conjugated molecule. Examples of such a dye include 3- [6- [4- [bis (2 ′, 4′-dibutyloxybiphenyl-4yl) amino-] phenyl] -4,4-dihexyl-cyclopenta- [2,1-b ; 3,4-b ′] dithiophene-2-yl] -2-cyanoacylic acid dye (chemical formula (4)) and the like, and it is preferable to use this dye. Further, the light absorbing material may be a metal complex. Examples of the metal contained in the metal complex include Zn, Cu, Fe, Pd, Pt, Ni, Co, Ru, and the like. Among these, Ru complexes (Ruthenizer 470 (Ru470), N719, Z907, etc.), metal porphyrin dyes (PtTPTBP, PdTPTBP, DTBC, etc.), metal phthalocyanine dyes (CuPc, ZnPc, etc.) and metal naphthalocyanine dyes (CuNc, ZnNc) Etc.) may be one or more. These light absorbing materials may be used alone or in combination. Of these, Ru complex compounds (Z907, N719), Zn porphyrin compounds (DTBC), carbazole dyes (MK2), indoline double rhodanine compounds (D149 and D358) and the like are preferable. Examples of the organic metal halide compound as the light absorbing material include perovskite crystals such as CH ₃ NH ₃ PbI ₃ . The structural formulas of the exemplified compounds are shown in the following chemical formula. Although not shown in the following chemical formula, PdTPTBP is obtained by changing Pt of PtTPTBP to Pd, ZnPc is obtained by changing Cu of CuPc to Zn, and ZnNc is obtained by changing Cu of CuNc to Zn.

The hole transport layer 26 is a layer that is interposed between the photoelectrode 20 and the counter electrode 30 and contains a solid compound. This hole transport layer may be a solid p-type semiconductor layer. This hole transport layer may be composed of a Cu compound. Examples of the Cu compound include one or more of CuI, CuO, and Cu ₂ O. Of these, CuI is more preferable. The hole transport layer 26 may contain an additive compound containing a quaternary ammonium cation having a hydroxyl group. That is, the hole transport layer 26 is a solution in which the ratio (addition amount) of the additive compound concentration (M) to the compound concentration (M) constituting the hole transport layer 26 is 0.1% or more and 10% or less. It is good also as what is produced using. The content of the additive compound may be in the same range as the electron transport layer 24 described above, or may be in a different range.

  The separator 29 is formed in an I-shaped cross section so as to be adjacent to one side surface of the photoelectrode 20 on which the base layer 22, the electron transport layer 24 and the hole transport layer 26 are laminated. One end of the separator 29 is in contact with the groove 18 on the light transmitting conductive substrate 14. Thereby, the direct contact with the photoelectrode 20 and the counter electrode 30 is avoided. The separator 29 is made of an insulating material, and may be formed of, for example, glass beads, silicon dioxide (silica), rutile titanium oxide, or the like. The separator 29 is preferably an insulator in which silica particles are sintered. Silica particles are preferable for the separator because they have a low refractive index, low light scattering, and good light transmission.

  The counter electrode 30 is formed in an L-shaped cross section so as to contact the outer surface of the separator 29 and the back surface 27 of the hole transport layer 26. One end of the counter electrode 30 is connected to the back surface of the hole transport layer 26, and the other end is connected to the adjacent light transmitting conductive film 12 via the connection portion 21. The surface of the counter electrode 30 that is in contact with the back surface 27 faces the photoelectrode 20 at a predetermined interval. The counter electrode 30 is not particularly limited as long as it has conductivity and bondability with the hole transport layer 26, and examples thereof include Pt, Au, and carbon. Among these, carbon is preferable. Note that the counter electrode 30, the separator 29, and the like may have any shape as long as they match the configuration of the solar cell 40.

  The sealing material 32 can be used without particular limitation as long as it is an insulating member. As the sealing material 32, for example, a thermoplastic resin film such as polyethylene or an epoxy adhesive can be used.

  The protection member 34 is a member that protects the solar cell 40, and can be, for example, a moisture-proof film or protective glass. This protective member 34 may be omitted.

  When the solar cell 40 is irradiated with light from the light receiving surface 13 side of the light transmitting substrate 11, the light is transmitted to the electron transport layer 24 through the light receiving surface 15 of the light transmitting conductive film 12 and the light receiving surface 23 of the base layer 22. The light absorbing material absorbs light and generates electrons. The electrons move from the photoelectrode 20 to the adjacent counter electrode 30 via the light-transmitting conductive film 12 and the connection portion 21. In the solar cell 40, an electromotive force is generated by the movement of the electrons, and the power generation action of the battery is obtained. This solar cell module 10 is configured to include a Cu compound and an additive compound containing a quaternary ammonium cation having a hydroxyl group from the electron transport layer 24 to the hole transport layer 26, and output characteristics are improved. Yes.

  The solar cell module 10 can be manufactured through a substrate manufacturing process, an electron transport layer forming process, a hole transport layer manufacturing process, a separator forming process, a counter electrode forming process, and a protective member forming process as a manufacturing method. In the substrate manufacturing process, the light transmissive conductive film 12 is formed on the light transmissive substrate 11 while forming the grooves 18 between the plurality of light transmissive conductive films 12. In the electron transport layer forming step, an n-type semiconductor layer is formed on the light-transmitting conductive film 12 via the base layer 22, and the light absorbing material is adsorbed to the n-type semiconductor layer to form the electron transport layer 24. As the n-type semiconductor layer, it is preferable to use porous titanium oxide.

Next, the hole transport layer 26 is formed on the electron transport layer 24 by a hole transport layer forming step. In this step, a step of supplying a solution containing a compound (for example, a Cu compound) constituting the hole transport layer 26 and an additive compound containing a quaternary ammonium cation having a hydroxyl group to the back surface 25 of the electron transport layer 24 and drying it. This is performed a plurality of times, and the electron transport layer 24 is filled with the compound constituting the hole transport layer 26 and the additive compound, and the hole transport layer 26 is formed on the electron transport layer 24. In this manufacturing method, the filling step of filling the electron transport layer 24 with the compound constituting the hole transport layer 26 and the additive compound and the formation step of forming the hole transport layer 26 on the electron transport layer 24 are separated. It may be performed. This solution may be prepared by mixing a compound constituting the hole transport layer 26 and an additive compound in an organic solvent. At this time, a solution in which the ratio of the concentration of the additive compound to the concentration of the compound constituting the hole transport layer 26 is 0.1% or more and 10% or less, and more preferably 0.2% or more and 8% or less is used. . When the concentration ratio is 0.1% or more, the above-described effects (improvement of filling properties and suppression of leakage current) can be sufficiently obtained. Further, when the concentration ratio is 10% or less, the abundance of the additive compound in the electron transport layer 24 is suitable, and the solar cell output can be improved. As the additive compound, any one of the solar cells described above, for example, one or more of choline iodide, choline bromide, and choline chloride can be used. Examples of the organic solvent include nitrile compounds such as methoxypropionitrile and acetonitrile, lactone compounds such as γ-butyrolactone and valerolactone, and carbonate compounds such as ethylene carbonate and propylene carbonate. In this step, one or more Cu compounds of CuI, CuO, and Cu ₂ O may be used as the compound constituting the hole transport layer 26, and among these, CuI is preferably used. When the Cu compound is dissolved in the solvent, the Cu concentration of this solution can be set as appropriate, but it is preferably a saturated solution of the Cu compound. In this way, the Cu compound is easily solidified on the electron transport layer 24. The hole transport layer 26 may be formed, for example, by supplying the solution while heating and drying the light transmission substrate 11. The heating temperature is preferably set to a temperature range in which the volatilization of the organic solvent is promoted and the additive compound is sufficiently stable. For example, a range of 40 ° C. or higher and 120 ° C. or lower is preferable.

  Subsequently, in the separator forming step, a separator 29 is formed on the side surface of the photoelectrode 20 in alignment with the groove 18. In the counter electrode forming step, the counter electrode 30 is formed so as to contact the separator 29 and the hole transport layer 26. The counter electrode 30 may be carbon, for example. In the protective member forming step, the sealing material 32 is formed so as to cover each cell, and the protective member 34 is formed on the sealing material 32. In this way, the solar cell 40 and the solar cell module 10 with improved power generation characteristics can be produced.

  The solar cell 40 described in detail above can provide a novel solar cell with improved output characteristics and a method for manufacturing the solar cell. The reason why such an effect is obtained is presumed as follows. For example, in this additive compound, a hydroxyl group of a quaternary ammonium cation having a hydroxyl group has excellent affinity with an electron transport layer, while a binding site between a quaternary ammonium cation and an anion has excellent affinity with a hole transport layer. It is guessed. Therefore, this additive compound can further enhance the filling property of the hole transport layer 26 into the pores of the electron transport layer 24 and is interposed between the electron transport layer 24 and the hole transport layer 26. As a result, the generation of leakage current can be further suppressed. Therefore, in this solar cell 40, it is guessed that an output characteristic can be improved more.

  It should be noted that the present invention is not limited to the above-described embodiment, and it goes without saying that the present invention can be implemented in various modes as long as it belongs to the technical scope of the present invention.

  For example, in the embodiment described above, the solar cell module 10 is used. However, the solar cell module 10 is not particularly limited thereto, and the solar cell 40 may be used. It is good also as the photoelectrode 20 which has. FIG. 2 is a cross-sectional view illustrating an example of a schematic configuration of the solar cell 40. When the solar cell 40 is used as a single unit, the cross-section of the counter electrode 30 may be formed in a flat plate shape instead of an L shape as shown in FIG. Further, the separator 29 may be omitted.

  Hereinafter, an example in which the solar cell disclosed in this specification is specifically manufactured will be described as an experimental example. In the following examples, Experimental Examples 2 to 6 correspond to Examples, and Experimental Example 1 corresponds to a Comparative Example. Needless to say, the invention disclosed in this specification is not limited to the following examples, and can be implemented in various modes as long as they belong to the technical scope of the invention disclosed in this specification.

[Production of solar cells]
Dye-sensitized solar cells were prepared using various additives, and their performance was examined. Here, CuI was used as the hole transport layer (solid p-type semiconductor layer), and an indoline double rhodanine red organic dye (Dye 1; D358) was used as the light absorbing material. First, on a TCO glass substrate, a porous titanium oxide film is applied as an electron transport layer (n-type semiconductor layer of the porous semiconductor layer) by screen printing, dried at 150 ° C., and then heated to 450 ° C. in an electric furnace. A titanium oxide film substrate was produced by heating. Next, a dye solution in which acetonitrile and tert-butyl alcohol in which 0.4 mM of the dye 1 was dissolved was mixed was prepared. Next, the titanium oxide film substrate was respectively immersed in the dye solution containing the produced dye 1 and allowed to stand under a temperature condition of 25 ° C. for 15 hours. Thus, the board | substrate which adsorb | sucked the pigment | dye 1 to the titanium oxide film board | substrate was produced. Subsequently, CuI was saturated with acetonitrile, and an optional compound was optionally added to prepare a CuI solution. Here, the ratio of the concentration (M) of the additive compound to the saturation concentration (0.16 M) of CuI is 0%, 0.6%, 1.9%, 3.1%, 6.3%, 9.4%. A solution was prepared. As an additive compound, choline iodide represented by the chemical formula (1) was used. Subsequently, the obtained dye-adsorbed titanium oxide film substrate was placed on a hot plate at 40 ° C. to 120 ° C. so that the titanium oxide film was on top. 10 μL of the prepared CuI solution was dropped on the dye-adsorbed titanium oxide film, and the solvent contained in the CuI solution was evaporated to fill the dye-adsorbed titanium oxide film with CuI and the additive compound. In this way, a photoelectrode was produced. Subsequently, the dropping of the CuI solution and the evaporation of the solvent were repeated to form a CuI layer (hole transport layer) on the dye-adsorbed titanium oxide film. And the Pt thin film as a counter electrode was arrange | positioned on this CuI layer, and the dye-sensitized solar cell shown in FIG. 2 was produced.

(Experimental Examples 1-6)
In the production of the dye-sensitized solar cell, a solar cell produced without using an additive was defined as Experimental Example 1. In addition, a solar cell manufactured using a CuI solution containing 3.1% of choline iodide as an additive compound with respect to the concentration (M) of CuI was defined as Experimental Example 2. Further, solar cells made of CuI solutions containing 0.6%, 1.9%, 6.3%, and 9.4% of choline iodide as an additive compound with respect to the concentration (M) of CuI are respectively experimental examples. It was set to 3-6.

[Examination of dependence of additive compound addition amount on solar cell output]
About the dye-sensitized solar cell of Experimental Examples 1-6, the solar cell output by 1000 lux LED light source irradiation was evaluated. The current-voltage characteristic (IV characteristic) when the solar cell was irradiated with 1000 lux light from the LED light source was measured using an IV tester (IV-9701 manufactured by Wacom Denso) to determine the output of the solar cell. .

[AC impedance measurement]
Using a frequency analyzer (5080, manufactured by NF ELECTRONIC INSTRUMENTS) and a potentiostat (HZ-3000, manufactured by Hokuto Denko), AC impedance measurement of the dye-sensitized solar cells of Examples 1 and 2 was performed. With respect to Experimental Examples 1 and 2, the alternating current impedance when white light was irradiated from the LED light source at an illuminance of 1000 lux was measured.

(Results and discussion)
Table 1 summarizes the output measurement results of the solar cell in which the measurement result of Experimental Example 1 was normalized to “1”. Table 1 summarizes the addition rate (%) of choline iodide, photocurrent, photovoltage and output. In addition, Table 2 summarizes the addition rate (%) of choline iodide and outputs in Experimental Examples 1 to 6. FIG. 3 is a result of examining the relative output of the solar cells of Experimental Examples 1 to 6. In Table 2 and FIG. 3, the result of normalizing the output of Experimental Example 2 to “100” is shown. As shown in Table 1, it was found that in Experimental Example 2 in which choline iodide was added, the photocurrent, photovoltage, and output increased compared to Experimental Example 1 in which no choline iodide was added, and a large addition effect was obtained. Further, as shown in Table 2 and FIG. 3, it can be seen that the addition amount of the additive compound is very effective even when the ratio of the additive compound concentration (M) to the CuI concentration (M) is 0.6%. It was. Moreover, although this addition amount tends to decrease when it exceeds 6%, it has been found that high output improvement can be obtained even at 9.4%. It was speculated that a high output increase could be obtained when the amount of the additive compound added was in the range of 0.1% to 10%.

  FIG. 4 shows AC impedance measurement results when the solar cells of Experimental Examples 1 and 2 are irradiated with 1000 lux light. As shown in FIG. 4, in Example 1 in which no additive compound was added, the internal resistance of the cell was large, whereas in Example 2 in which 3.1% of the additive compound choline iodide was added, the internal resistance was low. It was found that the output was greatly reduced and the output of the solar cell was improved.

[SEM observation of structure]
The cross sections of the solar cells of Experimental Examples 1 and 2 were observed with an ultra high resolution field emission scanning electron microscope manufactured by Hitachi High-Technologies. FIG. 5 is an FE-SEM image (reflection electron image and secondary electron image) of a cross section of the solar cell of Experimental Example 1. 6 is an FE-SEM image (reflected electron image and secondary electron image) of a cross section of the solar cell of Experimental Example 2. FIG. As shown in FIG. 5, when no additive was added, only titanium oxide and Cul crystals were observed. On the other hand, in Experimental Example 2 in which choline iodide was added, as shown in FIG. 6, in addition to the Cul crystal filled in the titanium oxide porous film, there was a region inferred as a complex of choline iodide and Cul. It was confirmed (dotted circle in the figure). Such a region also exists at the interface between titanium oxide and Cul, and it was assumed that it contributed to the output improvement. Furthermore, since such a region exists as a solid, it is presumed that movement and disappearance are suppressed as compared with liquid.

  The solar cell disclosed in the present specification can be used, for example, as a power source for various electric appliances for home use, office use, and factory use, batteries for electric vehicles, hybrid vehicles, electric bicycles, and solar panels.

  DESCRIPTION OF SYMBOLS 10 Solar cell module, 11 Light transmission substrate, 12 Light transmission conductive film, 13 Light reception surface, 14 Light transmission conductive substrate, 15 Light reception surface, 16, 17 Current collection electrode, 18 Groove, 20 Photo electrode, 21 Connection part, 22 Underlayer, 23 Light-receiving surface, 24 Electron transport layer, 25 Back surface, 26 Hole transport layer, 27 Back surface, 29 Separator, 30 Counter electrode, 32 Sealing material, 34 Protection member, 40 Solar cell.

Claims (9)

A photoelectrode having an electron transport layer coated with a light absorbing layer and comprising an additive compound comprising a quaternary ammonium cation having a hydroxyl group;
A solid hole transport layer interposed between the photoelectrode and the counter electrode;
Solar cell with   The solar cell according to claim 1, wherein the additive compound includes the quaternary ammonium cation having an alkyl group having 5 or less carbon atoms.   The solar cell according to claim 2, wherein the additive compound includes the quaternary ammonium cation in which the hydroxyl group is connected to a carbon chain longer than the alkyl group. The said additive compound is a solar cell of any one of Claims 1-3 which is 1 or more among the compounds shown by following formula (1)-(3).
  The photoelectrode and the hole transport layer are added in a range where the ratio of the concentration (M) of the additive compound to the concentration (M) of the compound constituting the hole transport layer is 0.1% or more and 10% or less. The solar cell of any one of Claims 1-4 containing a compound.   The solar cell according to claim 1, wherein the hole transport layer includes a Cu compound.   The said photoelectrode is a solar cell of any one of Claims 1-6 which has one or more said light absorption layers among an organic pigment | dye, a metal complex, and an organic metal halide compound.   The solar cell module provided with two or more solar cells of any one of Claims 1-7. A method for producing a solar cell in which a hole transport layer is interposed between a photoelectrode having an electron transport layer coated with a light absorption layer and a counter electrode disposed so as to face the photoelectrode,
A filling step of filling the electron transport layer with the Cu compound and the additive compound using a solution containing an additive compound containing a quaternary ammonium cation having a hydroxyl group and a Cu compound constituting the hole transport layer. A method for manufacturing a solar cell.