Solar cell

Abstract

To provide a solar cell capable of achieving high energy conversion efficiency while reducing material cost.SOLUTION: A solar cell includes: a pair of electrodes 2 and 3; and an active layer 1 that is located between the pair of electrodes 2 and 3 and absorbs light to generate electrons and holes. The pair of electrodes is composed of an electron collecting electrode 3 that collects electrons and a hole collecting electrode 2 that collects holes. The electron collecting electrode 3 contains carbon nanotubes 31 and an electron donating material 32.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a solar cell. [Background technology]

[0002] Solar cells have traditionally used transparent electrodes that are electrically conductive. Indium tin oxide (ITO) is currently the most widely used transparent electrode material. However, indium is a rare metal, and there are concerns about its cost and supply stability.

[0003] In response to this, Patent Document 1 discloses a solar cell that uses a carbon nanotube film as a translucent electrode. By employing a carbon nanotube film as a translucent electrode, high energy conversion efficiency can be achieved at low cost. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 7191310 Summary of the Invention [Problem to be solved by the invention]

[0005] Carbon nanotubes become p-type semiconductors, especially when handled in air, and have the ability to transport and collect holes. For this reason, carbon nanotube films are generally used in solar cells as hole-collecting electrodes.

[0006] In response to this, the present inventors investigated the use of a carbon nanotube film as an electron-collecting electrode that captures electrons. However, it became clear that when a carbon nanotube film is used as an electron-transporting electrode, the ability to transport and collect electrons may be insufficient. For this reason, it is difficult to employ a carbon nanotube film as an electron-collecting electrode, and there is a possibility that the effect of reducing material costs will not be fully achieved.

[0007] In view of the above, an object of the present invention is to provide a solar cell that can achieve high energy conversion efficiency while reducing material costs. [Means for solving the problem]

[0008] In order to achieve the above object, the solar cell according to claim 1 comprises a pair of electrodes (2, 3); A solar cell including an active layer (1) located between a pair of electrodes and absorbing light to generate electrons and holes, The pair of electrodes is composed of an electron collecting electrode (3) that collects electrons and a hole collecting electrode (2) that collects holes, The electron collecting electrode contains carbon nanotubes (31) and an electron donating material (32).

[0009] According to this, by incorporating carbon nanotubes and an electron donor material into the electron collecting electrode, the main carriers in the electron collecting electrode can be converted from holes to electrons. Therefore, even when carbon nanotubes are used as the electron collecting electrode, electrons generated in the active layer can be collected. Therefore, since carbon nanotubes can be used as the electron collecting electrode, it is possible to achieve high energy conversion efficiency while reducing material costs.

[0010] The symbols in parentheses for each means described in this section and in the claims indicate the correspondence with the specific means described in the embodiments described later. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is an explanatory diagram showing a stacked structure of a solar cell according to an embodiment; [Figure 2] FIG. 2 is an explanatory diagram showing an electron collecting electrode, an electron transport layer, and an active layer in one embodiment. [Figure 3] FIG. 3 is an enlarged view of part III in FIG. 2. [Figure 4] FIG. 1 is a characteristic diagram showing the relationship between the temperature difference and the thermoelectromotive force in a CNT transparent electrode. [Figure 5] FIG. 10 is a characteristic diagram showing the relationship between current and voltage when irradiated with light. [Figure 6] FIG. 10 is an explanatory diagram showing an electron collecting electrode, an electron transport layer, and an active layer in a comparative example. [Figure 7] FIG. 10 is an explanatory diagram showing a layered structure of a solar cell according to another embodiment (2). DETAILED DESCRIPTION OF THE INVENTION

[0012] An embodiment of the present disclosure will now be described with reference to the drawings. As shown in Figure 1, a solar cell 10 of this embodiment includes an active layer 1, a pair of electrodes 2 and 3, a light-transmitting substrate 4, a hole transport layer 5, and an electron transport layer 6.

[0013] The active layer 1 is disposed between a pair of electrodes 2 and 3. The active layer 1 is a photoelectric conversion element that absorbs light and generates electrons and holes.

[0014] The pair of electrodes 2, 3 is composed of a hole collecting electrode 2 and an electron collecting electrode 3. The hole collecting electrode 2 collects holes generated by light absorption in the active layer 1. The electron collecting electrode 3 collects electrons generated by light absorption in the active layer 1 and transports the collected electrons to an external circuit (not shown).

[0015] As an example, in this embodiment, the hole-collecting electrode 2 is a light-transmitting electrode, and the electron-collecting electrode 3 is a counter electrode. The hole-collecting electrode 2 is provided directly or indirectly on a light-transmitting substrate 4. In this specification, "provided indirectly" means that the electrode is provided via another film or the like.

[0016] The hole transport layer 5 extracts holes generated in the active layer 1 to the hole collecting electrode 2 side, and blocks electrons from flowing into the hole collecting electrode 2 side. The hole transport layer 5 is provided directly or indirectly on the hole collecting electrode 2. The active layer 1 is provided directly or indirectly on the hole transport layer 5.

[0017] The electron transport layer 6 extracts electrons generated in the active layer 1 to the electron collecting electrode 3 side, and blocks holes from flowing into the electron collecting electrode 3 side. The electron collecting electrode 3 is provided directly or indirectly on the active layer 1. The electron collecting electrode 3 is provided directly or indirectly on the electron transport layer 6.

[0018] That is, the solar cell 10 of this embodiment includes an active layer 1, a hole collecting electrode 2, an electron collecting electrode 3, a light-transmitting substrate 4, a hole transport layer 5, and an electron transport layer 6. The solar cell 10 of this embodiment is a solar cell element in which the light-transmitting substrate 4, the hole collecting electrode 2, the hole transport layer 5, the active layer 1, the electron transport layer 6, and the electron collecting electrode 3 are formed in this order. Each component will be described in detail below.

[0019] The light-transmitting substrate 4 is not particularly limited as long as it is a substrate that transmits light. Examples of the light-transmitting substrate 4 that can be used include transparent glass substrates such as quartz, soda-lime glass, and alkali-free glass, ceramic substrates, and light-transmitting plastic substrates. Examples of the light-transmitting plastic substrate that can be used include substrates made of polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, polyimide, nylon, polystyrene, polyvinyl alcohol, ethylene-vinyl alcohol copolymers, fluororesin films, polyolefins such as vinyl chloride and polyethylene, cellulose, polyvinylidene chloride, aramid, polyphenylene sulfide, polyurethane, polycarbonate, polyarylate, polynorbornene, and epoxy resins. As an example, in this embodiment, a transparent glass substrate is used as the light-transmitting substrate 4.

[0020] The active layer 1 is not particularly limited as long as it contains a substance capable of performing photoelectric conversion. The active layer 1 generally contains an electron acceptor and an electron donor.

[0021] When light is irradiated onto the active layer 1, the light is absorbed by the active layer 1, and electron transfer occurs at the interface between the electron acceptor and the electron donor, generating electrons and holes. The generated electrons and holes are extracted from the electron collecting electrode 3 and the hole collecting electrode 2, respectively.

[0022] The material of the active layer 1 may be either an inorganic compound or an organic compound, but it is preferable to use an organic compound.

[0023] Examples of electron donors that can be used in the active layer 1 include condensed aromatic hydrocarbons such as naphthacene, pentacene, and pyrene; thiophenes (polythiophenes) containing a thiophene ring, such as α-sexithiophene; condensed polycyclic aromatic compounds such as pentacene and tetracene; phthalocyanine compounds and metal complexes thereof, porphyrin compounds such as tetrabenzoporphyrin and metal complexes thereof, macrocyclic compounds such as naphthalocyanine derivatives and porphyrin derivatives; conjugated polymer semiconductors such as polyfluorene, polyphenylenevinylene, polythienylenevinylene, polyacetylene, and polyaniline; oligomer semiconductors such as oligothiophenes substituted with alkyl groups or other substituents; and organic dyes such as diketopyrrolopyrrole derivatives and squaraine derivatives.

[0024] Specific examples of electron donors that can be used include benzoporphyrin (BP), polythiophene, polyphenylene, polyphenylenevinylene, polysilane, polycarbazole, polyvinylcarbazole, porphyrin, polyacetylene, polypyrrole, polyaniline, polyfluorene, polyvinylpyrene, polyvinylanthracene, thiophene-fluorene copolymer, polyalkylthiophene, phenyleneethynylene-phenylenevinylene copolymer, phenyleneethynylene-thiophene copolymer, phenyleneethynylene-fluorene copolymer, fluorene-phenylenevinylene copolymer, thiophene-phenylenevinylene copolymer, phthalocyanine-containing polymer, carbazole-containing polymer, various low band gap polymers, and organometallic polymers.

[0025] Examples of the electron acceptor for the active layer 1 include fullerene or a fullerene derivative; a fused ring tetracarboxylic acid diimide such as naphthalene tetracarboxylic acid diimide or perylene tetracarboxylic acid diimide; and a fused polycyclic aromatic hydrocarbon such as a perylene derivative, a thiazole derivative, a benzothiazole derivative, or a benzothiadiazole derivative.

[0026] Specific examples of the electron acceptor include polyphenylene vinylene, polyfluorene, derivatives thereof, copolymers thereof, carbon nanotubes (CNTs), and phenyl C 61 Examples of suitable polymers include fullerene derivatives such as methyl-3-butylate (PCBM), polymers containing cyano (CN) groups or trifluoromethyl (CF3) groups, CF3 group-substituted polymers, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), 7,7,8,8-tetracyanoquinodimethane (TCNQ), 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA), and perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA).

[0027] Examples of fullerene derivatives that can be used include hydrogenated fullerene, oxidized fullerene, hydroxylated fullerene, aminated fullerene, sulfurized fullerene, halogenated (F, Cl, Br, I) fullerene, fulleroid, methanofullerene, pyrrolidinofullerene, alkylated fullerenes, and arylated fullerene.

[0028] Unless otherwise specified, the term "fullerene" used herein refers to, for example, fullerene C 60 , fullerene C 70 , fullerene C 76 , fullerene C 78 , fullerene C 82 , fullerene C 84 , fullerene C 90 , fullerene C 94 , fullerene C 96 etc. can be used.

[0029] Furthermore, a compound having a perovskite structure (perovskite compound) can be used for the active layer 1. Examples of perovskite compounds include CH3NH3PbI3- x Cl x (wherein x is 1 to 3), CH3NH3PbBr3, CH3NH3PbBrI2, CH3NH3PbBr2I, CH3NH3SnBr3, CH3NH3SnI3, CH(=NH)NH3PbI3, (C2H5NH3)2PbI4, (CH2=CHNH3)2PbI4, (CH≡CNH3)2PbI4, (C6H5NH3)2PbI4, (C6H3F2NH3)2PbI4, (C6F5NH3)2PbI4, (C4H3SNH3)2PbI4, etc. Among these compounds, CH3NH3PbI3 compound or CH3NH3PbI3- x Cl x It is preferable to use a compound (wherein x is 1 to 3) for the active layer 1. As an example, in this embodiment, a CH3NH3PbI3 compound (that is, a MAPbI3 compound) is used for the active layer 1.

[0030] The hole-collecting electrode 2 is a translucent electrode that is translucent to at least visible light contained in sunlight. The hole-collecting electrode 2 may be made of any material as long as it is translucent, and may be made of, for example, oxide-based materials such as indium tin oxide (ITO), tin oxide, zinc oxide, or titanium oxide. As an example, in this embodiment, an indium tin oxide electrode (ITO electrode) is used as the hole-collecting electrode 2.

[0031] For example, a conductive polymer such as poly(3,4-ethylenedioxythiophene)poly(styrenesulfonic acid) (PEDOT:PSS) or poly(bis(4-phenyl)(2,4,6-trimethylphenyl)amine) (PTAA) can be used as the hole transport layer 5. In this embodiment, as an example, PEDOT:PSS is used as the hole transport layer 5.

[0032] 2 and 3, the electron collecting electrode 3 contains carbon nanotubes 31, an electron donating material 32, and an electron transporting material 33. For clarity of illustration, in Fig. 3, the electron transporting material 33 is shown scattered around the carbon nanotubes 31, but the electron transporting material 33 is actually filled throughout the entire electron collecting electrode 3 (i.e., arranged without any gaps).

[0033] The carbon nanotubes 31 may be, for example, single-walled carbon nanotubes (SWCNTs). The electron donating material 32 is added to facilitate the flow of electrons in the carbon nanotubes 31. That is, the electron donating material 32 is added to impart electrical conductivity to the carbon nanotubes 31. Adding the electron donating material 32 to the carbon nanotubes 31 can change the main carriers from holes to electrons. For this reason, in this embodiment, the Seebeck coefficient of the electron collecting electrode 3 is negative.

[0034] In the atmosphere, CNTs have holes injected into them due to oxidation by oxygen, and exhibit hole transport properties. However, by doping with the electron-donating material 32, the electron-donating material 32 removes oxygen, weakening the hole transport properties, and it is expected that electrons will be injected, giving the CNT the electron transport properties.

[0035] The electron donating material 32 can be at least one of a substance that can partially donate electrons to other materials due to the properties of a lone pair of electrons or an anionic moiety, and a substance that can donate electrons to other materials due to an alkali metal or alkaline earth metal.

[0036] The material that donates electrons by an alkali metal or alkaline earth metal refers to elemental metals such as lithium, sodium, potassium, and cesium, as well as salts of the above metals that are expected to generate elemental metals by decomposition during the vacuum deposition process. Examples of salts of the above metals that are expected to generate elemental metals by decomposition during the vacuum deposition process include LiF and CsCO3. The material that donates electrons by an alkali metal or alkaline earth metal also includes fullerenes containing alkali metals. Examples of fullerenes containing alkali metals include Li@C 60 , Li@C 70 , Na@C 60 etc.

[0037] Specifically, as the electron donating material 32, at least one compound selected from the group consisting of compounds represented by the following chemical formulas 1 to 8 can be used.

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[0046] As an example, in this embodiment, triphenylphosphine (TPP) is used as the electron donating material 32.

[0047] The electron transport material 33 is added to increase the contact points between the electron transport layer 6, which is the underlying layer, and the carbon nanotubes 31, and to more efficiently transport electrons from the electron transport layer 6 to the carbon nanotubes 31. The electron transport material 33 is also expected to penetrate into the gaps in the CNT network structure and protect the CNTs, which have been given the electron transport property by the electron donor material 32, from oxidation by oxygen in the atmosphere.

[0048] The electron transport material 33 has an electron mobility of 1×10 -8 cm 2 At least one of a substance having a conductivity of 1 / Vs or more and an n-type organic semiconductor containing fullerene or a fullerene derivative can be used.

[0049] Specifically, examples of the electron transport material 33 include CdS, GaN, In2S3, InGaZnO4, SnO2, SnS2, SrSnO3, SrTiO3, TiO2, Zn2SO4, ZnO, ZnTiO3, ZrSnO4, and C. 60 Fullerene, C 70 Fullerene, diphenylmethanofullerene (DPM), oligoether (OE), C 60 derivative, C 70 At least one compound selected from the group consisting of derivatives and compounds represented by the following chemical formulas 9 to 30 can be used.

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[0072] In Chemical Formula 30, R2 is a group represented by Chemical Formula 31 below.

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[0074] As an example, in this embodiment, the electron transport material 33 is (6,6)-phenyl C 61 Butyric acid methyl ester (PC 61 BM) is used.

[0075] The electron transport layer 6 may be made of the same compound as the electron transport material 33 contained in the electron collecting electrode 3. For example, the electron transport layer 6 may be made of PC 61 For example, in this embodiment, the electron transport layer 6 may be made of PCBM, mix-PCBM (for example, nanom (registered trademark) spectra E124 manufactured by Frontier Carbon Corporation). 61 BM is used.

[0076] (Example) Next, examples according to the present disclosure will be described. These examples are examples of the present disclosure, and the present disclosure is not limited to these examples.

[0077] (1) Preparation of evaluation samples In this example, a sample of an inverted perovskite solar cell was fabricated using the following materials and procedures.

[0078] (1-1) Material The following materials were prepared as the electrodes and layers of each sample.

[0079] (Sample A) Light-transmitting substrate 4 and hole-collecting electrode 2: transparent conductive film (ITO film) glass substrate Hole transport layer 5: PEDOT:PSS Active layer 1: MAPbI3 (perovskite) ·Electron transport layer 6: PC 61 BM Electron collecting electrode 3: Carbon nanotube Electron donating material 32 contained in electron collecting electrode 3: TPP Electron transport material 33 contained in electron collecting electrode 3: PC 61 BM (Sample B) The sample was the same as Sample A except that 1,2-bis(diphenylphosphino)ethane (DPPE) was used as the electron donating material 32 contained in the electron collecting electrode 3.

[0080] (Sample C) The electron collecting electrode 3 was similar to Sample A except that 1,1′-bis(diphenylphosphino)ferrocene (DPPF) was used as the electron donating material 32 contained therein.

[0081] (Sample D) The sample was the same as Sample A except that the electron donating material 32 was not added to the carbon nanotubes of the electron collecting electrode 3 .

[0082] (1-2) Preparation procedure (Sample A) A transparent conductive film (ITO film) glass substrate was subjected to UV / O3 treatment for 30 minutes with the ITO film facing up. Next, a PEDOT:PSS film (i.e., hole transport layer 5) was formed on the ITO film of the substrate. Specifically, the prepared PEDOT:PSS coating solution was spin-coated at 3000 rpm for 20 seconds and heated on a hot plate at 115°C for 10 minutes to form a PEDOT:PSS film.

[0083] Next, a perovskite layer (i.e., active layer 1) was deposited on the PEDOT:PSS film. Specifically, 355 mg of PbI2, 122 mg of MAI, 490 μL of N,N'-dimethyl sulfoxide (DMSO), and 55 μL of dimethylformamide (DMF) were mixed to prepare a perovskite precursor solution. The perovskite precursor solution was then spin-coated at 4000 rpm for 20 seconds, and 150 μL of chlorobenzene (CB) was added dropwise 7 seconds after the start of spinning. After spinning, the substrate was heated at 100 °C for 10 minutes to form a perovskite layer.

[0084] Next, a CNT transparent electrode (i.e., electron collecting electrode 3) was formed on the perovskite layer. Specifically, the CNT transparent electrode ( / collection filter) was transferred onto the perovskite layer, and only the collection filter was removed.

[0085] Next, the CNT transparent electrode was impregnated with the electron donating material 32. Specifically, 20 wt % / CB TPP was dropped onto the CNT transparent electrode, and then the electrode was rotated at 2000 rpm for 30 seconds using a spin coater to remove excess material.

[0086] Next, the CNT transparent electrode was impregnated with an electron transport material 33. Specifically, first, PC 61 30 mg of BM was dissolved in 1 mL of CB to prepare an electron transport material solution. The prepared electron transport material solution was then dropped onto the CNT transparent electrode impregnated with the electron donor material 32, and the electrode was then spun at 4000 rpm for 20 seconds using a spin coater to remove the excess.

[0087] (Sample B) The procedure was the same as that of Sample A, except that 10 wt % / CB DPPE was dropped onto the CNT transparent electrode when the electron donating material 32 was impregnated into the CNT transparent electrode.

[0088] (Sample C) The procedure was the same as that of Sample A, except that 10 wt % / CB DPPF was dropped onto the CNT transparent electrode when the electron donating material 32 was impregnated into the CNT transparent electrode.

[0089] (Sample D) The sample was the same as Sample A except that the step of impregnating the CNT transparent electrode with the electron donating material 32 was not carried out.

[0090] (2) Evaluation (2-2) Seebeck coefficient The relationship between the temperature difference between both ends of the CNT transparent electrode and the thermoelectromotive force was measured for Samples A to D prepared above. The results are shown in Figure 4. In Figure 4, a positive slope of the graph indicates a positive Seebeck coefficient, and a negative slope of the graph indicates a negative Seebeck coefficient.

[0091] 4, sample D, in which the CNT transparent electrode was not doped with the electron-donating material 32, had a positive Seebeck coefficient, whereas samples A to C, in which the CNT transparent electrode was doped with the electron-donating material 32, had negative Seebeck coefficients. This shows that doping the CNT transparent electrode with the electron-donating material 32 changes the film quality of the CNT transparent electrode from p-type to n-type.

[0092] (2-2) Conversion efficiency The relationship between current and voltage (current-voltage characteristics) when irradiated with light was measured for the samples A to D prepared above, and the results are shown in FIG.

[0093] 5, the conversion efficiency (PCE) of sample D, in which the CNT transparent electrode was not doped with the electron donating material 32, was 3.4%, whereas the conversion efficiency of samples A to C, in which the CNT transparent electrode was doped with the electron donating material 32, was significantly increased to 5.4% or more. Specifically, the conversion efficiency of sample A was 5.9%, that of sample B was 6.0%, and that of sample C was 5.4%.

[0094] In the embodiment described above, the carbon nanotubes 31 of the electron collecting electrode 3 are doped with the electron donating material 32. This allows the main carriers of the electron collecting electrode 3 to be changed from holes to electrons. Therefore, even if a carbon nanotube film is used as the electron collecting electrode 3, it is possible to collect electrons generated in the active layer 1. Therefore, since a carbon nanotube film can be used as the electron collecting electrode 3, there is no need to use rare metals. As a result, it is possible to achieve high energy conversion efficiency while reducing material costs.

[0095] As a comparative example, Fig. 6 shows the layered structure of the electron collecting electrode 3, electron transport layer 6, and active layer 1 in a solar cell 10 that uses a metal electrode as the electron collecting electrode 3. As shown in Fig. 6, in the solar cell 10 of the comparative example, the electron collecting electrode 3 is made of metal and has a high density, so that a sufficient interface can be formed between the electron collecting electrode 3 and the electron transport layer 6. This makes it possible to easily receive electrons generated in the active layer 1.

[0096] On the other hand, when a carbon nanotube film is used as the electron collecting electrode 3, the low density makes it impossible to form a sufficient interface between the electron collecting electrode 3 and the electron transport layer 6, making it difficult to receive electrons generated in the active layer 1. In other words, the small number of contact points between the electron collecting electrode 3 (i.e., the carbon nanotubes 31) and the electron transport layer 6 makes it difficult for electrons to flow from the electron transport layer 6 to the carbon nanotubes 31.

[0097] In contrast, in the solar cell 10 of this embodiment, the carbon nanotubes 31 of the electron collecting electrode 3 are doped with an electron transport material 33. As a result, as shown in Fig. 2, the electron transport material 33 can increase the number of contact points between the electron collecting electrode 3 and the electron transport layer 6, allowing electrons to flow efficiently from the electron transport layer 6 to the carbon nanotubes 31.

[0098] (Other embodiments) The present invention is not limited to the above-described embodiment, and various modifications can be made as follows without departing from the spirit of the present invention.

[0099] (1) In the above embodiment, an example was described in which an indium tin oxide electrode (ITO electrode) was used as the hole-collecting electrode 2, but this is not limiting. For example, a carbon nanotube film may be used as the hole-collecting electrode 2.

[0100] (2) In the above embodiment, the solar cell 10 is an inverted solar cell element having a light-transmitting substrate 4, a hole-collecting electrode 2, a hole-transporting layer 5, an active layer 1, an electron-transporting layer 6, and an electron-collecting electrode 3 formed in this order, but this is not limited to this. For example, the electron side and the hole side may be reversed with respect to the layered structure of the solar cell 10 in the above embodiment. That is, as shown in FIG. 7 , the solar cell 10 may be a solar cell element having a light-transmitting substrate 4, an electron-collecting electrode 3, an electron-transporting layer 6, an active layer 1, a hole-transporting layer 5, and a hole-collecting electrode 2 formed in this order.

[0101] The technical features of the solar cell disclosed in this specification are as follows: (Item 1) A pair of electrodes (2, 3); A solar cell comprising: an active layer (1) located between the pair of electrodes and absorbing light to generate electrons and holes; The pair of electrodes is composed of an electron collecting electrode (3) that collects the electrons and a hole collecting electrode (2) that collects the holes, The electron collecting electrode of the solar cell contains carbon nanotubes (31) and an electron donating material (32). (Item 2) 2. The solar cell according to item 1, wherein the electron collecting electrode has a negative Seebeck coefficient. (Item 3) 3. The solar cell according to item 1 or 2, wherein the electron collecting electrode contains an electron transport material (33). (Item 4) 4. The solar cell according to any one of items 1 to 3, wherein the electron donating material is at least one of a substance capable of partially donating electrons to other materials due to the properties of an electron lone pair or an anionic moiety, and a substance capable of donating electrons to other materials due to an alkali metal or an alkaline earth metal. (Item 5) 4. The solar cell according to any one of items 1 to 3, wherein the electron donating material is at least one compound selected from the group consisting of compounds represented by the above-mentioned chemical formulas 1 to 8. (Item 6) The electron transport material has an electron mobility of 1×10 -8 cm 2 4. The solar cell according to item 3, wherein the n-type organic semiconductor is at least one of a material having a conductivity of 100 Ω / Vs or more and an n-type organic semiconductor containing a fullerene or a fullerene derivative. (Item 7) The electron transport material is CdS, GaN, In2S3, InGaZnO4, SnO2, SnS2, SrSnO3, SrTiO3, TiO2, Zn2SO4, ZnO, ZnTiO3, ZrSnO4, C 60 Fullerene, C 70 Fullerene, diphenylmethanofullerene (DPM), oligoether (OE), C 60 derivative, C 70 4. The solar cell according to item 3, wherein the compound is at least one compound selected from the group consisting of derivatives and compounds represented by the above-mentioned chemical formulas 9 to 30. (Item 8) 8. The solar cell according to any one of items 1 to 7, wherein the active layer is composed of a perovskite compound. [Explanation of symbols]

[0102] 3 Electron collection electrode 31 Carbon nanotubes 32 Electron-donating materials

Claims

1. A pair of electrodes (2, 3) and A solar cell comprising an active layer (1) located between the pair of electrodes and which absorbs light to generate electrons and holes, The pair of electrodes is composed of an electron-collecting electrode (3) for collecting electrons and a hole-collecting electrode (2) for collecting holes. The electron collecting electrode contains a carbon nanotube (31) and an electron-donating material (32). The electron collection electrode is a solar cell containing an electron transport material (33).

2. The solar cell according to claim 1, wherein the Seebeck coefficient of the electron collection electrode is negative.

3. The solar cell according to claim 1 or 2, wherein the electron-donating material is at least one of a substance capable of partially donating electrons to another material due to the properties of electron lone pairs or anionic sites, and a substance capable of donating electrons to another material due to alkali metals or alkaline earth metals.

4. The solar cell according to claim 1 or 2, wherein the electron-donating material is at least one compound selected from the group consisting of compounds represented by the following chemical formulas 1 to 8. 【Chemistry 1】 【Chemistry 2】 【Transformation 3】 【Chemistry 4】 【Transformation 5】 【Transformation 6】 【Transformation 7】 【Transformation 8】

5. The aforementioned electron transport material has an electron mobility of 1 × 10⁻⁶ －８ cm ２ The solar cell according to claim 1 or 2, which is at least one of a substance with a coefficient of 1 / Vs or higher, and an n-type organic semiconductor containing a fullerene or a fullerene derivative.

6. The electron transport material is CdS, GaN, In ２ S ３ , InGaZnO ４ , SnO ２ , SnS ２ , SrSnO ３ , SrTiO ３ , TiO ２ , Zn ２ SO ４ , ZnO, ZnTiO ３ , ZrSnO ４ , C ６０ fullerene, C ７０ fullerene, diphenylmethanofullerene (DPM), oligoether (OE), C ６０ derivative, C ７０ derivative, and at least one compound selected from the group consisting of compounds represented by the following Chemical Formulas 9 to 30. The solar cell according to claim 1 or 2. 【Chemistry 9】 【Chemistry 10】 【Chemistry 11】 【Chemistry 12】 【Chemistry 13】 【Chemistry 14】 【Chemistry 15】 【Chemistry 16】 【Chemistry 17】 [Chemistry 18] 【Chemistry 19】 【Chemistry 20】 【Chemistry 21】 【Chemistry 22】 【Chemistry 23】 【Chemistry 24】 【Chemistry 25】 【Chemistry 26】 【Chemistry 27】 【Chemistry 28】 【Chemistry 29】 【Transformation 30】 However, in the above chemical formula 30, R ２ This is the group represented by the following chemical formula 31. 【Chemistry 31】

7. The solar cell according to claim 1 or 2, wherein the active layer is composed of a perovskite compound.

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