JP2012004206A - Photoelectric conversion element and solar battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element and a solar battery that can be stably manufactured and are excellent in photoelectric conversion efficiency and photoelectric conversion function.SOLUTION: In a photoelectric conversion element having a substrate, a first electrode, a photoelectric conversion layer containing a semiconductor material and sensitization dye, a hole transport layer and a second electrode which are successively provided in this order, the hole transport layer contains polymer A manufactured by polymerization using, as the polymerization unit, a component represented by the general formula (1), and the thickness of the hole transport layer is not less than 10 nm and not more than 200 nm.

Description

  The present invention relates to a dye-sensitized photoelectric conversion element and a solar cell configured using the photoelectric conversion element.

  In recent years, solar energy has attracted attention as an energy source due to environmental problems.

  And the method of converting into the electrical energy which is the energy form which is easy to utilize using the light and heat of sunlight energy is put into practical use.

  Among these methods, for example, a method of converting sunlight into electric energy is a typical example, and a photoelectric conversion element is used in this method.

  As photoelectric conversion elements, photoelectric conversion elements using inorganic materials such as single crystal silicon, polycrystalline silicon, amorphous silicon, cadmium telluride and indium copper selenide are widely used, and are widely used for so-called solar cells. Yes.

  Solar cells using photoelectric conversion elements using these inorganic materials require a high-purity product such as silicon used as a material that requires an advanced refining process, and the manufacturing process is due to a structure with a multilayer pn junction. There were problems such as complexity, many processes, and high manufacturing costs.

  On the other hand, research on photoelectric conversion elements using organic materials as simpler elements is also underway.

  For example, C.I. W. Tang: A pn-junction organic material obtained by bonding a perylenetetracarboxylic acid derivative, which is an n-type organic dye, and copper phthalocyanine, which is a p-type organic dye, as described in Applied Physics Letters, 48, 183 (1986). A photoelectric conversion element has been reported.

  In an organic photoelectric conversion element, in order to improve the short exciton diffusion length and the thinness of the space charge layer, which are considered to be weak points, the area of the pn junction simply laminating the organic thin film is greatly increased. Attempts to ensure a sufficient number of organic dyes involved in the separation are producing results.

  Also, for example, G. Yu, J .; Gao, J .; C. Humelen, F.M. Wudl and A.W. J. et al. Heeger: As described in Science, 270, 1789 (1996), an n-type electron conductive organic material and a p-type hole conductive polymer are combined in a film to dramatically increase the pn junction portion. Thus, charge separation is performed throughout the film. In 1995, Heeger et al. Proposed a photoelectric conversion element in which a conjugated polymer is a p-type conductive polymer and fullerene is mixed as an electron conductive material.

  Although these photoelectric conversion elements are gradually improving their characteristics, they have not yet been able to behave stably with high conversion efficiency.

  However, in 1991, Gratzel made porous titanium oxide as a compilation of enormous and detailed experiments on the sensitized photocurrent of the dye adsorbed on titanium oxide, and the area of charge separation (number of molecules contributing to charge separation). As a result, a photoelectric conversion element having a stable operation and a high conversion efficiency was successfully produced (for example, see Non-Patent Document 1).

  In this photoelectric conversion element, the dye adsorbed on the surface of the porous titanium oxide is photoexcited, electrons are injected from the dye into the titanium oxide to become dye cations, and the dye receives electrons from the counter electrode through the hole transport layer. As the hole transport layer, an electrolytic solution in which an electrolyte containing iodine is dissolved in an organic solvent is used.

  This photoelectric conversion element, combined with the stability of titanium oxide, has excellent reproducibility, and the scope of research and development is greatly expanded. This photoelectric conversion element is also called a dye-sensitized solar cell and has great expectations and attention. Have been bathed.

  In this method, it is not necessary to purify an inexpensive metal compound semiconductor such as titanium oxide to a high purity, an inexpensive semiconductor can be used, and usable light extends over a wide visible light range. , It has the advantage that sunlight with a large amount of visible light components can be effectively converted into electricity.

  However, since a ruthenium complex having a resource limitation is used for the photoelectric conversion layer, there is a problem that it is necessary to use an expensive ruthenium complex, and stability over time is not sufficient.

  In addition, as a further problem, since dye-sensitized solar cells operate using an electrolyte as described above, a separate mechanism is required to prevent the electrolyte and iodine from being retained, discharged, or dissipated. Had a point.

  Typical examples of other electrochemical elements having an electrolytic solution are lead-acid batteries and lithium batteries, but even these electrochemical elements that are modularized in a compact manner are recovered and recycled 100%. Not surprisingly, it is self-evident to induce secondary problems when dissipated species are newly accumulated in the environment.

  Development of an all-solid-state dye-sensitized solar cell that avoids the problem of the electrolyte and inherits the goodness of the dye-sensitized solar cell has been advanced.

  In this field, U.S. Bach, D.C. Lupo, P.M. Comte, J .; E. Moser, F.A. Weissortel, J. et al. Salbeck, H.M. Spreitzer and M.M. Gratzel, Nature, 395, 583 (1998), which uses an amorphous organic hole transfer agent, R. A. Kumara, S .; Kaneko, M .; kuya, A .; Konno and K.K. Tennakone: Key Engineering Materials, 119, 228 (2002), which uses copper iodide as the hole transfer agent is known. However, since the conductivity of the hole transfer agent is low, photoelectric conversion is still sufficient. It has not given efficiency.

  Furthermore, a typical example of a hole transfer agent having a relatively high conductivity is a polythiophene-based material, and an all-solid dye-sensitized solar cell using PEDOT as a hole transfer agent has been reported (for example, non-conductive) Patent Document 2).

  As polythiophene-based materials, conductive polymers derived from 3,4 alkylene dioxythiophene derivatives are known (see Patent Document 1).

  However, even if these materials are simply used, photoelectric conversion efficiency and operational stability are still not sufficient in a dye-sensitized solar cell.

JP 2005-170942 A

B. O'Regan and M.M. Gratzel: Nature, 353, 737 (1991) J. et al. Xia, N.A. Masaki, M .; Lira-Cantu, Y.M. Kim, K .; Jiang and S.J. Yanagida: Journal of the American Chemical Society, 130, 1258 (2008)

  This invention is made | formed in view of the said subject, The objective is to provide the photoelectric conversion element and solar cell which can be manufactured stably and are excellent in photoelectric conversion efficiency and the stability of a photoelectric conversion function. is there.

  The above object of the present invention can be achieved by the following means.

  1. In a photoelectric conversion element in which a substrate, a first electrode, a semiconductor and a photoelectric conversion layer containing a sensitizing dye, a hole transport layer and a second electrode are disposed in this order, the hole transport layer has the following general formula ( 1. A photoelectric conversion element comprising a polymer A produced by polymerization using the compound represented by 1) as a polymerization unit, wherein the hole transport layer has a thickness of 10 nm to 200 nm.

(In the formula, Ar ₁ is a residue of a partial structure represented by any of the following general formulas (2) to (5).

Ar _{2 to} Ar ₂₄ each represent a substituted or unsubstituted aryl group, and may be linked to each other to form a cyclic structure.

T ₁ represents a residue of a group represented by any one of the following general formulas (6) to (10), and X represents an oxygen atom, a sulfur atom, or a selenium atom.

R _{1A to} R _9A and R _{1B to} R _9B represent hydrogen, an alkoxy group, or an alkylamino group, and in each of the groups of adjacent groups (R _1A , R _1B ) to (R _9A , R _9B ) , At least one is an alkoxy group or an alkylamino group, and each group of groups may form a ring with each other.

n ₁ represents an integer of 2 to 8, and n ₂ is 1 or 2.

The carbon-carbon double bond may be either a cis isomer or a trans isomer. )
2. 2. The photoelectric conversion element as described in 1 above, wherein n ₁ is an integer of 3 to 8.

  3. X in said general formula (6)-(9) is a sulfur atom, The said photoelectric conversion element of 1 or 2 characterized by the above-mentioned.

4). The adjacent substituent groups (R _1A , R _1B ) to (R _9A , R _9B ) in the compounds represented by the general formulas (6) to (10) form an ethylenedioxy ring. 4. The photoelectric conversion element according to any one of 1 to 3, wherein the photoelectric conversion element is characterized.

  5. 5. The photoelectric conversion element according to any one of 1 to 4, wherein the polymer A is synthesized on the semiconductor.

  6). 6. The photoelectric conversion element according to any one of 1 to 5, wherein the semiconductor is titanium oxide.

  7). A solar cell comprising the photoelectric conversion device according to any one of 1 to 6 above.

  By the above means of the present invention, it is possible to provide a photoelectric conversion element and a solar cell which are excellent in production stability, excellent in photoelectric conversion efficiency and photoelectric conversion function.

It is a schematic cross section which shows an example of the photoelectric conversion element of this invention.

  The present invention relates to a photoelectric conversion element comprising a substrate, a first electrode, a semiconductor and a photoelectric conversion layer containing a dye, a hole transport layer and a second electrode in this order. It contains a polymer A produced by polymerization using a compound represented by the formula (1) as a polymerization unit, and the thickness of the hole transport layer is from 10 nm to 200 nm.

  In the present invention, in particular, the above-mentioned specific polymer A is used for the hole transport layer, and the film thickness of the hole transport layer is set to a specific thickness so that the photoelectric conversion efficiency and the stability of the photoelectric conversion function are excellent. Devices and solar cells can be provided.

(Photoelectric conversion element)
The photoelectric conversion element of the present invention will be described with reference to FIG.

  FIG. 1 is a schematic cross-sectional view showing an example of the photoelectric conversion element of the present invention.

  As shown in FIG. 1, the photoelectric conversion element 10 includes a substrate 1, a first electrode 2, a photoelectric conversion layer 6, a hole transport layer 7, and a second electrode 8 arranged in this order.

  The photoelectric conversion layer 6 contains a semiconductor and a pigment.

  Between the 1st electrode 2 and the photoelectric converting layer 6, it is preferable to have the barrier layer 3 for the purpose of a short circuit prevention, sealing, etc.

  The thickness of the hole transport layer refers to the film thickness d between the second electrode 8 and the photoelectric conversion layer 6.

  Sunlight enters from the direction of the arrow at the bottom of the figure.

  The manufacture example of the photoelectric conversion element of this invention is shown below.

  After the barrier layer 3 is deposited and formed on the substrate 1 (also referred to as a conductive support) to which the first electrode 2 is attached, a semiconductor layer made of a semiconductor is formed on the barrier layer 3, and the semiconductor surface is formed on the semiconductor surface. A photoelectric conversion layer 6 is formed by adsorbing a sensitizing dye. Thereafter, the hole transport layer 7 is formed on the photoelectric conversion layer 6.

  The hole transport layer 7 exists on a semiconductor layer made of a semiconductor carrying a sensitizing dye, and a second electrode 8 is attached thereon. Terminals can be attached to the first electrode 2 and the second electrode 8 to extract current.

(Hole transport layer)
The hole transport layer has the function of rapidly reducing the oxidant of the sensitizing dye after absorbing light and injecting electrons into the semiconductor, and transporting the holes injected at the interface with the dye to the second electrode. Is a layer.

  The hole transport layer contains a polymer A prepared by polymerization using a compound represented by the following general formula (1) as a polymerization unit, and the thickness of the hole transport layer is 10 nm or more and 200 nm or less.

  The thickness of the hole transport layer indicates a film thickness d between the second electrode 8 and the photoelectric conversion layer 6 as shown in FIG. Specifically, it is defined by the average distance between the lowermost surface of the second electrode and the uppermost surface of the photoelectric conversion layer. The distance between the side contour of the second electrode and the hole transport layer side contour surface of the photoelectric conversion layer was measured at 21 points at intervals of 0.1 μm, and the value of these points was arithmetically averaged between 2 μm in the electrode plane method. It is a value derived by doing.

(Polymer A)
(Compound represented by the general formula (1))
In the general formula (1), Ar ₁ is a residue having a partial structure represented by any one of the general formulas (2) to (5).

Ar _{2 to} Ar ₂₄ each represent a substituted or unsubstituted aryl group, and may be linked to each other to form a cyclic structure.

  Examples of the substituent include a halogen group such as a fluorine atom, a lower alkyl group having 1 to 3 carbon atoms, and the like.

  Examples of the substituted or unsubstituted aryl group include a phenyl group, a naphthyl group, a biphenyl group, a fluorenyl group, an anthryl group, a pyrenyl group, an azulenyl group, an acenaphthylenyl group, a terphenyl group, and a phenanthryl group.

  These may be connected to each other to form an annular structure.

T ₁ represents the residue of the group represented by any _one of the above general formulas (6) to (10), and X represents an oxygen atom, a sulfur atom or a selenium atom.

R _{1A to} R _9A and R _{1B to} R _9B represent hydrogen, an alkoxy group, or an alkylamino group, and in each of the groups of adjacent groups (R _1A , R _1B ) to (R _9A , R _9B ) , At least one is an alkoxy group or an alkylamino group, and each group of groups may form a ring with each other.

  Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, and a butoxy group. Examples of the alkylamino group include a dimethylamino group, a diethylamino group, and a methylethylamino group.

  Examples that mutually form a ring include a methylenedioxy ring, an ethylenedioxy ring, a propylenedioxy ring, and the like.

n ₁ represents an integer of 2 to 8, and n ₂ is 1 or 2.

  The carbon-carbon double bond may be either a cis isomer or a trans isomer.

The compound represented by the general formula (1) can be synthesized by a Grignard reaction between a halogen compound of Ar _{1 and} a halogen compound of T ₁ .

Synthesis Example Synthesis Example 1 (Synthesis of Exemplified Compound A-1)

3.95 g (2.78 × 10 ⁻² mol) of 3,4-ethylenedioxythiophene was dissolved in 10 ml of dehydrated dimethylformamide under a nitrogen atmosphere. To this solution, a solution prepared by dissolving 2.49 g (1.40 × 10 ⁻² mol) of N-bromosuccinimide (NBS) in 30 ml of dehydrated dimethylformamide (DMF) was added dropwise at room temperature (RT), and the solution was directly added at room temperature. Stir for hours. 50 ml of water and 50 ml of toluene were added to the reaction solution, and the organic phase was separated, dried over anhydrous magnesium sulfate and then concentrated under reduced pressure. The resulting residue was purified with a silica gel column to give 2-bromo-3, 2.49 g of a toluene solution of 4-ethylenedioxythiophene was obtained (containing 8.4 × 10 ⁻³ mol of the target product). Since it polymerized, no further concentration was performed.

A solution obtained by dissolving 1.11 g (3.7 × 10 ⁻³ mol) of the above-mentioned toluene solution of 2-bromo-3,4-ethylenedioxythiophene in 10 ml of dehydrated tetrahydrofuran (THF) It was dripped at 110 mg (4.52 * 10 < ^-3 > mol), and heating-refluxing was performed for 1 hour. The flask under different nitrogen atmosphere, tris (4-bromophenyl) amine 481 mg (9.99 × ^{10 -4} mol), bis (triphenylphosphine) palladium chloride (II) 21.7mg (3.1 × 10 - ⁵ mol) was suspended in 3 ml of dehydrated tetrahydrofuran. The aforementioned Grignard reaction solution was added dropwise to this suspension, and the reaction solution was heated to reflux for 4 hours. After cooling, 15 ml of saturated brine and 15 ml of ethyl acetate are added, the organic phase is separated, dried over anhydrous magnesium sulfate, and concentrated under reduced pressure. The resulting residue is purified by a silica gel column to give exemplified compounds 89.4 mg of A-1 was obtained (1.34 × 10 ⁻⁴ mol).

The ¹ H-NMR data of Example Compound A-1 obtained are shown below.

¹ HNMR (400 MHz, CDCl ₃ ): 4.24 (6H, t, OCH ₂ ), 4.30 (6H, t, OCH ₂ ), 6.26 (3H, s, thiophene-H), 7.08 ( 6H, d, ar-H), 7.57 (6H, d, ar-H)
Specific examples of the compound represented by the general formula (1) are shown below, but the present invention is not limited thereto.

  The polymer A is obtained by polymerizing the compound represented by the general formula (1) as a polymerization unit.

  The polymer A is obtained by polymerizing the compound represented by the general formula (1) as a polymerization unit, but may be obtained using only the compound represented by the general formula (1). Further, it may be a copolymer with another polymerizable compound, and is preferably a polymer using 10 mol% or more of the compound represented by the general formula (1).

  As the polymerization method, chemical polymerization using a polymerization catalyst, electrolytic polymerization using at least a working electrode and a counter electrode and reacting by applying a voltage between both electrodes, light irradiation alone or polymerization catalyst, heating, electrolysis, etc. There are combined photopolymerization methods and the like.

  When chemical polymerization is performed using a polymerization catalyst, there is no particular limitation as long as the compound represented by the general formula (1) is polymerized, but iron (III) chloride (iron (III) chloride), Iron (III) tris-p-toluenesulfonate (iron (III) tris-p-toluenesulfonate), iron (III) p-dodecylbenzenesulfonate (iron (III) p-dodecylbenzenesulfonate), iron (III) methanesulfonate (Iron (III) methanesulfonate), iron (III) p-ethylbenzenesulfonate (iron (III) p-ethylbenzenesulfonate), iron (III) naphthalenesulfonate (iron (III) naphthalenesulfonate) and hydrates thereof .

  The polymerization rate modifier used in the chemical polymerization is a weak complexing agent for trivalent iron ions in the polymerization catalyst, and is not particularly limited as long as it reduces the polymerization rate so that a film can be formed. When the catalyst is iron (III) chloride and its hydrate, aromatic oxysulfonic acid such as 5-sulfosalicylic acid can be used, and the polymerization catalyst can be tris-p- Iron (III) toluenesulfonate, iron (III) p-dodecylbenzenesulfonate, iron (III) methanesulfonate, iron (III) p-ethylbenzenesulfonate, iron (III) naphthalenesulfonate and hydrates thereof In some cases, such as imidazole.

  After the polymer A is synthesized, it may be contained in a coating solution containing the polymer A and supplied onto the photoelectric conversion layer, but it is preferably synthesized by polymerization on the photoelectric conversion layer. is there.

  In that case, in order to synthesize and synthesize the polymer A, a solution for forming a polymer coating film containing the compound represented by the general formula (1), the polymerization catalyst, the polymerization rate modifier and other additives Is used. The total concentration of each of the above components in the solution for forming a polymer coating film is the type of the compound represented by the general formula (1) to be used, the polymerization catalyst, the polymerization rate regulator, and other additives, The mass concentration is generally in the range of 1 to 50%, although it varies depending on the quantitative ratio, the conditions for the coating method and the desired film thickness after polymerization.

  After the polymerization coating film forming solution is applied on the photoelectric conversion layer by a coating method, or while the photoelectric reaction layer is immersed in the polymerization coating film forming solution, a polymerization reaction is performed.

  The conditions for the polymerization reaction are the compound represented by the general formula (1) to be used, the type of the polymerization catalyst, and the polymerization rate regulator, the amount ratio, the concentration, the thickness of the liquid film at the applied stage, Although it varies depending on the desired polymerization rate, preferable polymerization conditions include a range of heating temperature in the case of heating in air of 25 to 120 ° C. and a heating time of 1 minute to 24 hours.

  In the case of forming the hole transport layer by an electrolytic polymerization method, for example, it is performed as follows.

The compound represented by the general formula (1) is dissolved in a solvent such as acetonitrile, tetrahydrofuran, propylene carbonate, dichloromethane, o-dichlorobenzene, dimethylformamide and the like as a supporting electrolyte. Salts such as lithium acid, tetrabutylammonium perchlorate, and Li [(CF ₃ SO ₂ ) ₂ N] are added to prepare an electrolytic polymerization solution.

  The solvent is not particularly limited as long as it can dissolve the supporting electrolyte and the hole transport material. As the supporting electrolyte, those capable of ionization are used, and the supporting electrolyte is not limited to a specific one.

  In particular, those having high solubility in a solvent and hardly undergoing oxidation and reduction are preferably used.

Next, the substrate 1 on which the transparent conductive film 2, the barrier layer 3 and the photoelectric conversion layer 6 are formed is immersed in the electrolytic polymerization solution, the photoelectric conversion layer 6 is used as a working electrode, a platinum plate or the like is used as a counter electrode, and the reference electrode As a method of direct current electrolysis using Ag / AgCl or the like. The concentration of the hole transport material in the electrolytic polymerization solution is preferably about 0.1 to 1000 mmol / L, and the supporting electrolyte concentration is preferably about 0.1 to 2 mol / L. As the applied current ^density, it is more desirable is preferably in the range of ^{0.01mA / cm 2 ~1000mA / cm 2} , in particular in the range of ^{1mA / cm 2 ~500mA / cm 2} . The temperature range of the electropolymerization solution is suitably a range in which the solvent does not solidify or bump, and is generally -30 ° C to 80 ° C. Conditions such as electrolysis voltage, electrolysis current, electrolysis time, and temperature depend on the materials used, and can be appropriately selected according to the required film thickness.

  Although it is difficult to determine the degree of polymerization of the polymer with the compound of the present application, the solubility of the polymerized compound is greatly reduced. It is soaked in tetrahydrofuran (THF), which is a solvent that can be dissolved, and the solubility is judged.

  Specifically, 10 mg of a compound is taken in a 25 ml sample bottle, added to 10 ml of THF, and irradiated with ultrasonic waves (25 kHz, 150 W Ultrasonic Industry Co., Ltd., COLLECTOR CURRENT 1.5A Ultrasonic Industry 150) for 5 minutes. Further, when the dissolved compound is 5 mg or less, it is defined as polymerized.

  The polymer A uses a compound represented by the general formula (1) as a polymerization unit, but a polymerization unit other than the compound may be used in combination as long as the effects of the present invention are not impaired. Examples of these include thiophene derivatives, pyrrole derivatives, or furan derivatives.

  Examples of the polymerization site of the compound represented by the general formula (1) are exemplified below using the exemplified compound A-1 of the polymer A. The part marked with * is a single bond formed by bonding the polymerization sites. The compound A is a polymer using the compound represented by the general formula (1) as a polymerization unit as exemplified below.

  The band gap of the polymer A is preferably 2 eV or more, and more preferably 2.5 eV or more.

  Moreover, in order to reduce the oxidized form of the sensitizing dye, it is necessary to be smaller than the dye adsorption electrode ionization potential, and the preferred range of the ionization potential of the polymer A used for the hole transport layer differs depending on the dye used. However, it is preferably 4.5 eV or more and 5.5 eV or less, and more preferably 4.7 eV or more and 5.3 eV or less.

  When the hole transport layer is formed by coating, a coating solution containing the general formula (1) is used. As a solvent for this coating solution, tetrahydrofuran (THF), butylene oxide, chloroform, cyclohexanone, chlorobenzene, acetone , Polar solvents such as various alcohols, organic solvents such as aprotic solvents such as dimethylformamide (DMF), acetonitrile, dimethoxyethane, dimethyl sulfoxide, hexamethylphosphoric triamide, etc. Species or a combination of two or more can be used.

The hole transport layer, if necessary, for _{example, N (PhBr) 3 SbCl 6} , Li and _{[(CF 3 SO 2) 2} N] various additives such as may be added.

  As a coating method, various coating methods such as dipping, dropping, doctor blade, spin coating, brush coating, spray coating, and roll coater can be used.

  Further, the coating may be repeated by repeating such coating operation.

  The content of the polymer A in the hole transport layer is preferably 50 to 100% by mass, and more preferably 90 to 100% by mass.

  A hole transport layer having a thickness of 10 nm to 200 nm can be obtained by adjusting the concentration of the above-mentioned solution for forming a polymer coating film used when polymerizing on a semiconductor layer, adjusting the applied voltage and applying time in electrolytic polymerization. it can.

  The applied voltage (relative to the reference electrode) varies depending on the compound used for polymerization, but a range of about 0.4 V to -0.4 V is preferably used.

  By using the hole transport layer in the present invention, the reason why a photoelectric conversion element excellent in production stability, photoelectric conversion efficiency and photoelectric conversion function is obtained is not clear, but is estimated as follows.

  When the hole transport layer contains the polymer A, which is a polymer, hole transport due to intramolecular charge transfer along the polymerized molecular chain contributes to improve transport efficiency. Since the thickness of the hole transport layer is as thin as 200 nm or less and the loss during hole transport is small, the conversion efficiency is improved. In addition, the polymer A has a structure having a high molecular chain density while having a three-dimensional cross-linking structure, and has a film thickness of 10 nm or more. Therefore, the polymer A is stable against mechanical distortion and has few occurrences of short circuits. It is presumed that the reduction in conversion efficiency is prevented.

(substrate)
The substrate is provided on the light incident direction side, and from the viewpoint of photoelectric conversion efficiency of the photoelectric conversion element, the light transmittance is preferably 10% or more, more preferably 50% or more, and particularly 80% to 100%. % Is preferred.

  The light transmittance is the total light transmittance in the visible light wavelength region measured by a method according to “Testing method of total light transmittance of plastic-transparent material” of JIS K 7361-1 (corresponding to ISO 13468-1). Say.

  The material, shape, structure, thickness, hardness and the like of the substrate can be appropriately selected from known ones, but preferably have high light transmittance as described above.

  Examples of the substrate include polyester resin films such as polyethylene terephthalate (PET), polyethylene naphthalate, and modified polyester, polyolefins such as polyethylene (PE) resin film, polypropylene (PP) resin film, polystyrene resin film, and cyclic olefin resin. Resin films, vinyl resin films such as polyvinyl chloride and polyvinylidene chloride, polyvinyl acetal resin films such as polyvinyl butyral (PVB), polyether ether ketone (PEEK) resin films, polysulfone (PSF) resin films, polyether sal Hong (PES) resin film, polycarbonate (PC) resin film, polyamide resin film, polyimide resin film, acrylic resin film, triacetyl cellulose Loin (TAC) resin film, and the like. In addition to these resin films, an inorganic glass film may be used as the substrate.

  Any resin film having a transmittance of 80% or more at a visible wavelength (380 to 780 nm) can be particularly preferably applied to the present invention.

  Among them, from the viewpoint of transparency, heat resistance, ease of handling, strength and cost, it is preferably a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyethylene naphthalate film, a polyethersulfone film, or a polycarbonate film, and biaxially stretched. More preferred are polyethylene terephthalate films and biaxially stretched polyethylene naphthalate films.

  These substrates can be subjected to a surface treatment or an easy-adhesion layer in order to ensure wettability and adhesion of the coating solution.

  A conventionally well-known technique can be used about a surface treatment or an easily bonding layer. For example, the surface treatment includes surface activation treatment such as corona discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, glow discharge treatment, active plasma treatment, and laser treatment.

  Examples of the easy adhesion layer include polyester, polyamide, polyurethane, vinyl copolymer, butadiene copolymer, acrylic copolymer, vinylidene copolymer, and epoxy copolymer.

  The thickness of the substrate is preferably 1 to 1000 μm, and more preferably 10 to 100 μm.

(First electrode)
The first electrode is disposed between the substrate and the photoelectric conversion layer.

  As the first electrode, one having a light transmittance of 80% or more, more preferably 90% or more is preferably used. The light transmittance is the same as that described in the description of the substrate.

  The first electrode is provided on one surface that is opposite to the light incident direction of the substrate.

As an example of the material for forming the first electrode, it is preferable to use a metal (for example, platinum, gold, silver, copper, aluminum, rhodium, indium) or a metal oxide, for example, SnO ₂ , CdO, ZnO, CTO. Examples include CdSnO ₃ , Cd ₂ SnO ₄ , CdSnO ₄ , In ₂ O ₃ , CdIn ₂ O _{4, and the} like.

  Silver is preferably used as the metal, and a grid-patterned film having openings or a film in which fine particles or nanowires are dispersed and applied is preferably used in order to impart light transmittance.

  The metal oxide is preferably a composite (dope) material obtained by adding one or more selected from Sn, Sb, F and Al to the above metal oxide.

Of these, conductive metal oxides such as In ₂ O ₃ (ITO) doped with Sn, SnO ₂ doped with Sb, and SnO ₂ (FTO) doped with F are preferably used, from the viewpoint of heat resistance. FTO is most preferred.

  What has a 1st electrode on a board | substrate is called an electroconductive support body here.

  The film thickness of the conductive support is preferably in the range of 0.1 mm to 5 mm.

The surface resistance of the conductive support is preferably 50 Ω / cm ² or less, and more preferably 10 Ω / cm ² or less.

  The preferable range of the light transmittance of the conductive support is the same as the preferable range of the light transmittance of the substrate.

(Barrier layer)
The photoelectric conversion element of the present invention preferably has a barrier layer positioned between the first electrode and the semiconductor layer as a short-circuit prevention means.

  As described below, the barrier layer and the photoelectric conversion layer are preferably porous. In this case, the barrier layer has a porosity of C [%] and the semiconductor layer has a porosity of D [ %], The D / C is, for example, preferably about 1.1 or more, more preferably about 5 or more, and still more preferably about 10 or more.

  Thereby, a barrier layer and a semiconductor layer can exhibit those functions more suitably, respectively.

  More specifically, the porosity C of the barrier layer is, for example, preferably about 20% or less, more preferably about 5% or less, and further preferably about 2% or less. That is, the barrier layer is preferably a dense layer. Thereby, the said effect can be improved more.

  The average thickness (film thickness) of the barrier layer is, for example, preferably about 0.01 to 10 μm, and more preferably about 0.03 to 0.5 μm. Thereby, the said effect can be improved more.

The constituent material of this barrier layer is not particularly limited, for example, zinc, niobium, tin, titanium, vanadium, indium, tungsten, tantalum, zirconium, molybdenum, manganese, iron, copper, nickel, iridium, rhodium, chromium, Ruthenium or oxides thereof, and perovskites such as strontium titanate, calcium titanate, barium titanate, magnesium titanate, strontium niobate, or complex oxides or oxide mixtures thereof, CdS, CdSe, TiC, Si One kind or a combination of two or more kinds of various metal compounds such as ₃ N ₄ , SiC and BN can also be used.

  In particular, when the hole transport layer is a p-type semiconductor, a metal having a work function smaller than that of the hole transport layer and having a Schottky contact is used when a metal is used for the barrier layer. When a metal oxide is used for the barrier layer, it is preferable that the barrier layer is in ohmic contact with the transparent conductive layer and the energy level of the conduction band is lower than that of the porous semiconductor layer 4.

  At this time, the efficiency of electron transfer from the porous semiconductor layer (photoelectric conversion layer) to the barrier layer can be improved by selecting an oxide.

  Among these, those having electrical conductivity equivalent to that of the semiconductor layer (photoelectric conversion layer) are preferable, and those mainly composed of titanium oxide are more preferable.

(Photoelectric conversion layer)
The photoelectric conversion layer includes a semiconductor and a sensitizing dye, and includes a semiconductor layer containing the semiconductor carrying the sensitizing dye.

(semiconductor)
As a semiconductor used for the semiconductor layer, silicon, germanium, a compound having a group 3 to group 5, group 13 to group 15 element of a periodic table (also referred to as an element periodic table), metal Chalcogenides (for example, oxides, sulfides, selenides, etc.), metal nitrides, and the like can be used.

  Preferred metal chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium or tantalum oxides, cadmium, zinc, lead, silver, antimony or Bismuth sulfide, cadmium or lead selenide, cadmium telluride and the like. Examples of other compound semiconductors include phosphides such as zinc, gallium, indium and cadmium, gallium-arsenic or copper-indium selenide, copper-indium sulfide, titanium nitride, and the like.

Specific examples include TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO, Nb ₂ O ₅ , CdS, ZnS, PbS, Bi ₂ S ₃ , CdSe, CdTe, GaP, InP, GaAs, CuInS ₂ , CuInSe ₂ , Ti ₃ N _{4 and the} like can be mentioned, but TiO ₂ , ZnO, SnO ₂ , Fe ₂ O ₃ , WO ₃ , Nb ₂ O ₅ , CdS, and PbS are preferably used. Is TiO ₂ or Nb ₂ O ₅ , among which TiO ₂ (titanium oxide) is particularly preferably used.

  As the semiconductor used for the semiconductor layer, a plurality of the above-described semiconductors may be used in combination.

For example, several kinds of the metal oxides or metal sulfides described above can be used in combination, or 20% by mass of titanium nitride (Ti ₃ N ₄ ) may be mixed and used in the titanium oxide semiconductor.

  In addition, J.H. Chem. Soc. Chem. Commun. 15 (1999). At this time, when a component is added as a semiconductor in addition to the metal oxide or metal sulfide, the mass ratio of the additional component to the metal oxide or metal sulfide semiconductor is preferably 30% or less.

  Further, the semiconductor according to the present invention may be surface-treated using an organic base. Examples of the organic base include diarylamine, triarylamine, pyridine, 4-t-butylpyridine, polyvinylpyridine, quinoline, piperidine, and amidine, among which pyridine, 4-t-butylpyridine, and polyvinylpyridine are preferable. .

  Surface treatment can be carried out by preparing a solution dissolved in an organic solvent as it is when the organic base is liquid, or by immersing the semiconductor according to the present invention in a liquid organic base or organic base solution.

<< Fabrication of semiconductor layer >>
A method for manufacturing the semiconductor layer will be described.

  In the case where the semiconductor of the semiconductor layer is in the form of particles, the semiconductor layer is preferably manufactured by applying or spraying the semiconductor onto a conductive support. In the case where the semiconductor according to the present invention is in a film form and is not held on the conductive support, it is preferable to produce a semiconductor layer by bonding the semiconductor onto the conductive support.

  As a preferred embodiment of the semiconductor layer, a method of forming the semiconductor layer by firing using fine particles of semiconductor on the conductive support can be mentioned.

  When the semiconductor according to the present invention is produced by firing, the semiconductor sensitization (adsorption, filling in a porous layer, etc.) treatment with a dye is preferably performed after firing. It is particularly preferable to perform the compound adsorption treatment quickly after the firing and before the water is adsorbed to the semiconductor.

  Hereinafter, a method for forming a semiconductor layer preferably used in the present invention by firing using semiconductor fine powder will be described in detail.

(Preparation of coating liquid containing semiconductor fine powder)
First, a coating solution containing fine semiconductor powder is prepared. The finer the primary particle diameter of the semiconductor fine powder, the better. The primary particle diameter is preferably 1 to 5000 nm, more preferably 2 to 100 nm. The coating liquid containing the semiconductor fine powder can be prepared by dispersing the semiconductor fine powder in a solvent.

  The semiconductor fine powder dispersed in the solvent is dispersed in the form of primary particles. The solvent is not particularly limited as long as it can disperse the semiconductor fine powder.

  Examples of the solvent include water, an organic solvent, and a mixed solution of water and an organic solvent. As the organic solvent, alcohols such as methanol and ethanol, ketones such as methyl ethyl ketone, acetone and acetyl acetone, hydrocarbons such as hexane and cyclohexane, and the like are used. A surfactant and a viscosity modifier (polyhydric alcohol such as polyethylene glycol) can be added to the coating solution as necessary. The range of the semiconductor fine powder concentration in the solvent is preferably 0.1 to 70% by mass, and more preferably 0.1 to 30% by mass.

(Application of coating solution containing fine semiconductor powder and baking treatment of the formed semiconductor layer)
The semiconductor fine powder-containing coating solution obtained as described above is applied or sprayed onto a conductive support, dried, etc., and then baked in air or in an inert gas, on the conductive support. A semiconductor layer (also referred to as a semiconductor film) is formed.

  A film obtained by applying and drying a coating solution containing semiconductor fine powder on a conductive support is composed of an aggregate of semiconductor fine particles, and the particle size of the fine particles is equal to the primary particle size of the semiconductor fine powder used. Corresponding.

  Thus, the semiconductor fine particle layer formed on the conductive layer such as the conductive support is weak in bonding strength with the conductive support and fine particles, and has low mechanical strength. The semiconductor fine particle layer is baked to increase the mechanical strength and form a semiconductor layer that is strongly fixed to the substrate.

  The semiconductor layer may have any structure, but is preferably a porous structure film (also referred to as a porous layer having voids).

  When the semiconductor layer is a porous structure film, it is preferable that components such as a hole transport material of the hole transport layer are also present in this void.

  Here, the porosity of the semiconductor layer is preferably 10% by volume or less, more preferably 8% by volume or less, and particularly preferably 0.01 to 5% by volume. The porosity of the semiconductor layer means a porosity that is penetrable in the thickness direction of the dielectric, and can be measured using a commercially available apparatus such as a mercury porosimeter (Shimadzu pore sizer 9220 type).

  As for the film thickness of the semiconductor layer used as the baked material film | membrane which has a porous structure, 10 nm or more is preferable at least, More preferably, it is 500-30000 nm.

  From the viewpoint of appropriately preparing the actual surface area of the fired film during the firing treatment and obtaining a fired film having the above porosity, the firing temperature is preferably lower than 1000 ° C, more preferably in the range of 200 to 800 ° C. Especially preferably, it is the range of 300-800 degreeC.

  In addition, when the substrate is made of plastic or the like and is inferior in heat resistance, the fine particles and the fine particle-substrate can be fixed by pressurization without performing a baking process at 200 ° C. or higher, or the substrate can be formed by microwaves. Only the semiconductor layer can be heat-treated without heating.

  The ratio of the actual surface area to the apparent surface area can be controlled by the particle size, specific surface area, firing temperature, etc. of the semiconductor fine particles.

  In addition, after heat treatment, in order to increase the efficiency of electron injection from the dye to the semiconductor particles by increasing the surface area of the semiconductor particles or increasing the purity in the vicinity of the semiconductor particles, Plating or electrochemical plating using a titanium trichloride aqueous solution may be performed.

(Sensitizing dye)
The sensitizing dye according to the present invention is supported on a semiconductor by a semiconductor sensitization treatment as described below, and can be photoexcited to generate an electromotive force when irradiated with light. As the sensitizing dye, known sensitizing dyes used for photoelectric conversion elements can be used.

  From the viewpoint of efficient injection of charges into the semiconductor, the sensitizing dye preferably has a carboxyl group. Although the specific example of a sensitizing dye is shown below, this invention is not limited to these.

(Semiconductor sensitization treatment)
The total supported amount of the dye of the present invention per 1 m ^{2 of the} semiconductor layer is preferably in the range of 0.01 to 100 mmol, more preferably 0.1 to 50 mmol, and particularly preferably 0.5 to 20 mmol.

  When performing the sensitization treatment, sensitizing dyes may be used alone or in combination, and other compounds (for example, US Pat. No. 4,684,537, US Pat. No. 4,927). No. 721, No. 5,084,365, No. 5,350,644, No. 5,463,057, No. 5,525,440, JP-A-7- 249790, JP-A 2000-150007, etc.) can also be used as a mixture.

  In particular, when the use of the photoelectric conversion element of the present invention is a solar cell to be described later, two or more types of dyes having different absorption wavelengths are used so that the wavelength range of photoelectric conversion can be made as wide as possible to effectively use sunlight. It is preferable to use a mixture.

  In order to support a sensitizing dye on a semiconductor, a method in which a semiconductor which is dissolved in an appropriate solvent (ethanol or the like) and dried well in the solution is immersed for a long time is generally used.

  When using multiple types of sensitizing dyes or other dyes for sensitizing treatment, a mixed solution of each dye may be prepared and used, or a separate solution for each dye Can be prepared and immersed in each solution in order.

  When preparing different solutions for each sensitizing dye and immersing them in each solution in order, the order in which the sensitizing dye and the like are included in the semiconductor may be whatever.

  Alternatively, it may be produced by mixing fine particles of semiconductor adsorbing the dye alone.

  In the case of a semiconductor having a high porosity, it is preferable to complete the adsorption treatment of a sensitizing dye or the like before water is adsorbed on the semiconductor thin film and in the voids inside the semiconductor thin film due to moisture, water vapor, etc. .

  The semiconductor sensitization treatment is performed by dissolving the sensitizing dye in an appropriate solvent as described above and immersing the substrate obtained by firing the semiconductor in the solution.

  In that case, it is preferable that a substrate on which a semiconductor layer (also referred to as a semiconductor film) is formed by baking be subjected to pressure reduction treatment or heat treatment in advance to remove bubbles in the film. Such treatment allows the sensitizing dye to enter deep inside the semiconductor layer (semiconductor film), and is particularly preferable when the semiconductor layer (semiconductor film) is a porous structure film.

  The solvent used for dissolving the sensitizing dye is not particularly limited as long as it can dissolve the sensitizing dye and does not dissolve the semiconductor or react with the semiconductor.

  However, in order to prevent moisture and gas dissolved in the solvent from entering the semiconductor film and hindering sensitizing treatment such as adsorption of a sensitizing dye, it is preferable to deaerate and purify in advance.

  Solvents preferably used for dissolving the sensitizing dye include nitrile solvents such as acetonitrile, alcohol solvents such as methanol, ethanol and n-propanol, ketone solvents such as acetone and methyl ethyl ketone, diethyl ether, diisopropyl ether, tetrahydrofuran, 1 Ether solvents such as 1,4-dioxane and halogenated hydrocarbon solvents such as methylene chloride and 1,1,2-trichloroethane, and a plurality of solvents may be mixed. Particularly preferred are acetonitrile, acetonitrile / methanol mixed solvent, methanol, ethanol, acetone, methyl ethyl ketone, tetrahydrofuran and methylene chloride.

(Tensing temperature and time)
It is preferable that the time for immersing the substrate on which the semiconductor is baked in the solution containing the sensitizing dye penetrates deeply into the semiconductor layer (semiconductor film) to sufficiently advance adsorption and the like to sufficiently sensitize the semiconductor.

  In addition, from the viewpoint of suppressing degradation of the dye produced in the solution by decomposition or the like and hindering the adsorption of the dye, it is preferably 3 to 48 hours under 25 ° C., more preferably 4 to 24 hours. is there.

  This effect is particularly remarkable when the semiconductor film is a porous structure film.

  However, the immersion time is a value under the condition of 25 ° C., and is not limited to the above when the temperature condition is changed.

  In soaking, the solution containing the dye of the present invention may be heated to a temperature that does not boil as long as the dye does not decompose. A preferable temperature range is 5 to 100 ° C., more preferably 25 to 80 ° C., but this is not the case when the solvent boils in the temperature range as described above.

(Second electrode)
The 2nd electrode should just have electroconductivity, and arbitrary electroconductive materials are used. Even an insulating material can be used if a conductive material layer is provided on the side facing the hole transport layer.

  It is preferable that the contact property with the hole transport layer is good. Further, it is preferable that the work function difference with the hole transport layer is small and chemically stable. As such a material, a metal thin film such as gold, silver, copper, aluminum, or platinum, or an organic conductor such as carbon black or a conductive polymer can be used.

(Solar cell)
The solar cell of the present invention has the photoelectric conversion element of the present invention.

  The solar cell of the present invention comprises the photoelectric conversion element of the present invention, has a structure in which optimal design and circuit design are performed for sunlight, and optimal photoelectric conversion is performed when sunlight is used as a light source. Have.

  That is, the semiconductor is dye-sensitized and can be irradiated with sunlight. When configuring the solar cell of the present invention, it is preferable that the photoelectric conversion layer, the hole transport layer, and the second electrode are housed in a case and sealed, or the whole is resin-sealed.

  When the solar cell of the present invention is irradiated with sunlight or an electromagnetic wave equivalent to sunlight, the sensitizing dye supported on the semiconductor is excited by absorbing the irradiated light or electromagnetic wave.

  Electrons generated by excitation move to the semiconductor, and then move to the second electrode via the conductive support and the external load, and are supplied to the hole transporting material of the hole transporting layer.

  On the other hand, the sensitizing dye that has moved electrons to the semiconductor is an oxidant, but is reduced by being supplied with electrons from the second electrode via the polymer A of the hole transport layer. At the same time, the polymer A in the hole transport layer is oxidized and returned to a state where it can be reduced again by the electrons supplied from the second electrode.

  In this way, electrons flow, and a solar cell using the photoelectric conversion element of the present invention can be configured.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these.

Example [Preparation of Photoelectric Conversion Element SC-1 (Invention)]
An inorganic glass film having a thickness of 30 μm is used as a substrate, and an FTO (fluorine-doped tin oxide) thin film is provided on one side by spray pyrolysis to obtain a transparent conductive film having a sheet resistance of 10Ω / □ and the first electrode. did. Even when this inorganic glass film was wound around a round bar having a diameter of 5 cm, the occurrence of breakage and cracks were not observed.

  4 ml of titanium tetraisopropoxide, 1 ml of water, and 40 ml of ethanol solution were mixed, and further hydrochloric acid was added to adjust the pH to 1. This titanium oxide precursor solution was spin-coated at 1000 rpm on the aforementioned FTO glass substrate. This was dried by heating at 100 ° C. for 15 minutes. Further, it was baked at 450 ° C. for 10 minutes to form a dense barrier layer made of a titanium oxide thin film having a thickness of 30 to 50 nm.

Titanium oxide paste (anatase type, primary average particle size (microscope observation average) 18 nm, ethyl cellulose dispersion) was applied to the FTO glass substrate on which the barrier layer was formed by screen printing (application area 25 mm ² ). Firing was performed at 200 ° C. for 10 minutes and at 500 ° C. for 15 minutes to obtain a titanium oxide thin film having a thickness of 2.5 μm. Dye D-1 was dissolved in a mixed solvent of acetonitrile: t-butyl alcohol = 1: 1 to prepare a solution of 5 × 10 ⁻⁴ mol / l. The FTO glass substrate coated and sintered with the above titanium oxide was immersed in this solution at room temperature for 3 hours for dye adsorption treatment to form a photoelectric conversion layer to obtain a semiconductor electrode.

The semiconductor electrode contains the compound A-1 represented by the general formula (1) at a ratio of 1 × 10 ⁻³ (mol / l), and tetrabutylammonium perchlorate is 0.1 (mol / l). It was immersed in an acetonitrile solution (electropolymerization solution) contained at a ratio of The working electrode was the semiconductor electrode, the counter electrode was a platinum wire, the reference electrode was Ag / Ag ⁺ (AgNO ₃ 0.01M), and the holding voltage was −0.16V. While irradiating light from the semiconductor layer direction (using a xenon lamp, light intensity of 22 mW / cm ² , cutting a wavelength of 430 nm or less), the voltage was maintained for 30 minutes to form a hole transport layer on the surface of the semiconductor electrode. The obtained semiconductor electrode / hole transport layer was washed with acetonitrile and dried.

  The hole transport layer obtained here is a polymer film that is insoluble in the solvent.

After that, in acetonitrile solution containing Li [(CF ₃ SO ₂ ) ₂ N] at a rate of 15 × 10 ⁻³ (mol / l) and tert-butylpyridine at a rate of 50 × 10 ⁻³ (mol / l) for 10 minutes. Soaked.

  Thereafter, the semiconductor electrode / hole transport layer was naturally dried, and then gold was deposited by 90 nm by a vacuum deposition method to produce a second electrode, thereby obtaining a photoelectric conversion element SC-1.

  One separator of the acrylic transparent adhesive having a thickness of 20 μm sandwiched between the double-sided separators was peeled off, and the exposed adhesive surface was adhered to one side of a polyethylene terephthalate film having a thickness of 40 μm using a rubber roller.

  Two single-sided adhesive films were prepared, and the solar cell 1 was produced by sticking on both surfaces of the element produced previously using a rubber roller.

  Nine samples of photoelectric conversion elements similar to the photoelectric conversion element SC-1 were produced, and were designated as photoelectric conversion elements SC1-1 to SC1-10, respectively. Ten samples of the same sample were prepared for the following samples.

[Production of Photoelectric Conversion Elements SC-2 to SC-21 and Solar Cells 2 to 21]
In preparation of the photoelectric conversion element 1, the sensitizing dye described in Table 1 is used as the sensitizing dye, and the hole transport layer material (compound represented by the general formula (1)) A-1 is described in Table 1. Photoelectric conversion elements SC-2 to 21 and solar cells 2 to 21 were produced in the same manner except that the compound was changed.

In the photoelectric conversion element SC-17, an acetonitrile solution containing 5 × 10 ⁻⁴ (mol / l) each of A-1 and A-R2 was used as the electrolytic polymerization solution.

In the photoelectric conversion element SC-18, an acetonitrile solution containing 1 × 10 ⁻⁴ (mol / l) A-1 and 9 × 10 ⁻⁴ (mol / l) A-R2 was used as the electrolytic polymerization solution. .

[Production of Photoelectric Conversion Element SC-22, Production of Solar Cell 22 (Comparative Example)]
In the production of the solar cell 1, the photoelectric conversion element SC-22 and the solar cell 22 were produced in the same manner as the production of the solar cell 1 except that A-R1 was used instead of A-1 as the electrolytic polymerization solution. .

[Production of Photoelectric Conversion Element SC-23, Production of Solar Cell 23 (Comparative Example)]
In the production of the solar cell 1, the photoelectric conversion element SC-23 and the solar cell 23 were produced in the same manner except that the holding voltage during electrolysis was set to + 0.6V.

[Production of Photoelectric Conversion Element SC-24, Production of Solar Cell 24 (Comparative Example)]
In the production of the solar cell 1, the photoelectric conversion element SC-24 and the solar cell 24 were produced in the same manner except that the holding voltage during electrolysis was set to -0.6V.

[Evaluation of photoelectric conversion element]
The produced solar cell was irradiated with 100 mW / cm ² pseudo-sunlight from a xenon lamp through an AM filter (AM-1.5) using a solar simulator (manufactured by Eiko Seiki).

  That is, for a solar cell including a photoelectric conversion element, current-voltage characteristics are measured at room temperature using an IV tester, and a short circuit current (Jsc), an open circuit voltage (Voc), and a form factor (FF) are measured. ) And the photoelectric conversion efficiency (η (%)) was determined from these. In addition, the conversion efficiency ((eta) (%)) of the photoelectric conversion element was computed based on the following formula (A).

η = 100 × (Voc × Jsc × FF) / P (A)
Here, P is the incident light intensity [mW / cm ⁻² ], Voc is the open circuit voltage [V], Jsc is the short circuit current density [mA · cm ⁻² ], F. Indicates a form factor.

  The photoelectric conversion efficiency after each solar cell was wound on a round bar having a diameter of 7 cm for 10 minutes was also measured, the efficiency ratio before and after bending was determined, and used as an index of stability of the conversion efficiency.

  The film thickness of the hole transport layer was determined from a sectional view of the photoelectric conversion element by SEM. Table 1 shows the result of characteristic evaluation of each photoelectric conversion element.

  The values listed in the table are average values of 10 photoelectric conversion elements. Table 1 shows the number of conversion efficiency within ± 10% of the average value as an index of production stability.

  From Table 1, only the photoelectric conversion elements (SC-1 to 21) of the present invention having the hole transport layer containing the polymer A and having a thickness of 10 nm to 200 nm can be stably produced. It can be seen that the photoelectric conversion efficiency and the stability of the photoelectric conversion function are excellent.

1 Substrate 2 First Electrode 3 Barrier Layer 6 Photoelectric Conversion Layer 7 Hole Transport Layer 8 Second Electrode 10 Photoelectric Conversion Element

Claims (7)

In a photoelectric conversion element in which a substrate, a first electrode, a semiconductor and a photoelectric conversion layer containing a sensitizing dye, a hole transport layer and a second electrode are disposed in this order, the hole transport layer has the following general formula ( 1. A photoelectric conversion element comprising a polymer A produced by polymerization using the compound represented by 1) as a polymerization unit, wherein the hole transport layer has a thickness of 10 nm to 200 nm.

(In the formula, Ar ₁ is a residue of a partial structure represented by any of the following general formulas (2) to (5).

Ar _{2 to} Ar ₂₄ each represent a substituted or unsubstituted aryl group, and may be linked to each other to form a cyclic structure.
T ₁ represents a residue of a group represented by any one of the following general formulas (6) to (10), and X represents an oxygen atom, a sulfur atom, or a selenium atom.

R _{1A to} R _9A and R _{1B to} R _9B represent hydrogen, an alkoxy group, or an alkylamino group, and in each of the groups of adjacent groups (R _1A , R _1B ) to (R _9A , R _9B ) , At least one is an alkoxy group or an alkylamino group, and each group of groups may form a ring with each other.
n ₁ represents an integer of 2 to 8, and n ₂ is 1 or 2.
The carbon-carbon double bond may be either a cis isomer or a trans isomer. ) The photoelectric conversion element according to claim 1, wherein the n ₁ is an integer of 3 to 8.   X in the said General formula (6)-(9) is a sulfur atom, The photoelectric conversion element of Claim 1 or 2 characterized by the above-mentioned. The adjacent substituent groups (R _1A , R _1B ) to (R _9A , R _9B ) in the compounds represented by the general formulas (6) to (10) form an ethylenedioxy ring. The photoelectric conversion element according to any one of claims 1 to 3, wherein the photoelectric conversion element is characterized in that   The photoelectric conversion element according to any one of claims 1 to 4, wherein the polymer A is synthesized on the semiconductor.   The photoelectric conversion element according to claim 1, wherein the semiconductor is titanium oxide.   It has a photoelectric conversion element of any one of Claim 1 to 6, The solar cell characterized by the above-mentioned.

Images