Perovskite solar cell and carbon liquid

Abstract

To provide a perovskite solar cell and a carbon liquid having a counter electrode in which the decrease in photoelectric conversion efficiency is suppressed.SOLUTION: An electrode layer 62 contains a residue obtained by drying a carbon liquid dispersed in an alcohol-based solvent 62b in a perovskite solar cell 10 having an electrode layer 62 disposed adjacent to a hole transport layer 5.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to perovskite solar cells and carbon liquids. [Background technology]

[0002] Solar cells generally use elements such as silicon, compound semiconductors, and organic semiconductors. Recently, perovskite solar cells have been attracting attention due to their high light-harvesting capacity, thin film construction, and low cost.

[0003] Patent Document 1 discloses a perovskite solar cell (solar cell in Patent Document 1) having, in this order, a photoelectrode (cathode in Patent Document 1), a power generation layer (photoelectric conversion layer in Patent Document 1), and a counter electrode (anode in Patent Document 1). In this perovskite solar cell, the power generation layer contains an organic-inorganic perovskite compound represented by the general formula RM-X3 (where R is an organic molecule, M is a metal atom, and X is a halogen atom or a chalcogen atom). Furthermore, this perovskite solar cell has, between the counter electrode and the power generation layer, a diffusion prevention layer made of at least one material selected from the group consisting of metal oxides, metal nitrides, and metal oxynitrides containing metals from Groups 6 to 15 of the periodic table, and carbon. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2018 / 056295 Summary of the Invention [Problem to be solved by the invention]

[0005] The perovskite solar cell disclosed in Patent Document 1 has a diffusion prevention layer between the counter electrode and the power generation layer to prevent the metal material of the counter electrode from diffusing into the photoelectric conversion layer containing an organic-inorganic perovskite compound. This allows the perovskite solar cell to maintain a high photoelectric conversion efficiency even when a voltage is applied to the solar cell over a long period of time. However, as shown in Comparative Examples 3 and 4 of Patent Document 1, when a diffusion prevention layer made of carbon is used as the counter electrode, the photoelectric conversion efficiency decreases.

[0006] This phenomenon is observed, for example, when an aqueous carbonaceous liquid is applied as a counter electrode. When the counter electrode is formed by applying an aqueous carbonaceous liquid to a hole transport layer and drying it, the carbonaceous liquid penetrates into the hole transport layer before drying, and even into the perovskite layer, which is the underlying layer of the hole transport layer. Because the perovskite layer is sensitive to moisture, the penetration of the carbonaceous liquid may reduce the photoelectric conversion efficiency.

[0007] Furthermore, if a water-free solvent is used to prevent the carbon solution from penetrating the hole transport layer or perovskite layer, the dispersibility of the carbon in the solvent may decrease, potentially worsening the conductivity of the counter electrode. Furthermore, depending on the dispersion conditions, the solvent may absorb moisture from the air when dispersing the carbon, and in that case, the moisture absorbed by the solvent may penetrate into the perovskite layer.

[0008] Therefore, there is a demand for a perovskite solar cell and a carbon solution having a counter electrode in which the decrease in photoelectric conversion efficiency is suppressed. [Means for solving the problem]

[0009] One embodiment of a perovskite solar cell according to the present disclosure is a perovskite solar cell having an electrode layer disposed adjacent to a hole transport layer, the electrode layer comprising a residue obtained by drying a carbon liquid dispersed in an alcohol-based solvent.

[0010] According to this embodiment, an alcohol-based solvent with low moisture absorption (water absorption) in the air is used, so that moisture in the air is less likely to be absorbed when dispersing carbon. Therefore, in a carbon solution using the alcohol-based solvent, the moisture in the alcohol-based solvent is prevented from penetrating into the hole transport layer or the perovskite layer. As a result, even if the electrode layer contains a residue from drying the carbon solution, a perovskite solar cell can be obtained that has low sheet resistance and photoelectric conversion efficiency comparable to that of a gold electrode.

[0011] One embodiment of the carbon liquid used to form the electrode layer of the perovskite solar cell has a composition of 5% by weight or more and 20% by weight or less of graphite, 5% by weight or more and 20% by weight or less of carbon black, 1.0% by weight or more and 15% by weight or less of a resin component, and 45% by weight or more and 89% by weight or less of the alcohol-based solvent.

[0012] If the carbon solution used to form the electrode layer of a perovskite solar cell has this composition, it is possible to obtain a perovskite solar cell having an electrode layer containing carbon that has low sheet resistance and photoelectric conversion efficiency comparable to that of a gold electrode. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic cross-sectional view of a perovskite solar cell. [Figure 2] FIG. 1 is a top perspective view of a perovskite solar cell. [Figure 3] FIG. 1 is a cross-sectional view illustrating the power generation principle of a perovskite solar cell. [Figure 4] 1A to 1C are explanatory diagrams showing the manufacturing procedure of a perovskite solar cell. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the perovskite solar cell and carbon liquid according to the present disclosure will be described in detail with reference to the drawings. Note that the embodiments described below are examples for explaining the perovskite solar cell and carbon liquid, and the perovskite solar cell and carbon liquid are not limited to these embodiments. Therefore, the perovskite solar cell and carbon liquid according to the present disclosure can be embodied in various forms without departing from the spirit thereof.

[0015] [Basic structure of solar cells] As shown in FIGS. 1 and 2 , a perovskite solar cell 10 according to this embodiment (hereinafter simply referred to as the solar cell 10) includes a substrate 2 and a laminate 11 provided on the substrate 2. The substrate 2 includes a transparent substrate 21 and a transparent conductive film 22. The laminate 11 includes a blocking layer 3, a power generation layer 4, and a hole transport layer 5. The blocking layer 3 is provided on the transparent conductive film 22 and transfers electrons to the transparent conductive film 22, while separating the hole transport layer 5 from the transparent conductive film 22 to prevent recombination of electrons and holes (reverse electron transfer). The power generation layer 4 is provided on the blocking layer 3 and is formed by laminating a perovskite layer 44, which is excited by light to generate electrons, on a porous semiconductor 41. The hole transport layer 5 is provided on the power generation layer 4 and allows holes generated in the perovskite layer 44 to pass through. Furthermore, a photoelectrode 61 that emits electrons is provided on the surface of the blocking layer 3 via the transparent conductive film 22, and a counter electrode 62 (an example of an electrode layer) that receives electrons is provided on the surface of the hole transport layer 5. The counter electrode 62 is an anode. The counter electrode 62 is formed from the surface of the hole transport layer 5, passing over the side surfaces of the hole transport layer 5 and the perovskite layer 44, and extending to the surface of the blocking layer 3. Hereinafter, the photoelectrode 61 and the counter electrode 62 will be collectively referred to as electrode 6. Note that the arrangement of the electrode 6 is not particularly limited as long as it allows electron transfer; for example, the photoelectrode 61 may be formed by connecting a conductor to the transparent conductive film 22. Furthermore, to increase the durability of the solar cell 10, the counter electrode 62 may be protected by a transparent substrate 21 or the like.

[0016] The transparent substrate 21 is made of a light-transmitting material. Examples of the transparent substrate 21 include a transparent glass substrate, a frosted semi-transparent glass substrate, and a transparent resin substrate. Examples of the transparent conductive film 22 include fluorine-doped tin oxide (FTO), tin oxide (TO), tin-doped indium oxide (ITO), zinc oxide (ZnO), and aluminum-doped zinc oxide (AZO).

[0017] Metal oxides are suitable for the blocking layer 3 and the porous semiconductor 41, and examples thereof include titanium dioxide (TiO2), zinc oxide (ZnO), niobium oxide (Nb2O5), tin dioxide (SnO2), and aluminum oxide (Al2O3). In particular, it is preferable to use a sintered body of titanium dioxide (TiO2), which can secure a large surface area for stacking the perovskite layer 44. Furthermore, a portion of the blocking layer 3 extends into a recess 221 formed by removing a portion of the transparent conductive film 22 to form the insulating layer 31, thereby dividing the transparent conductive film 22 into two. In the blocking layer 3, electrons can move in the stacking direction, but have difficulty moving laterally, which is perpendicular to the stacking direction. Furthermore, electrons cannot move between the two transparent conductive films 22 separated by the insulating layer 31. In other words, electrons that enter the blocking layer 3 move smoothly in the stacking direction of the transparent conductive film 22 and are supplied to the photoelectrode 61, but since the insulating layer 31 prevents them from moving laterally toward the counter electrode 62, there is no short circuit between the photoelectrode 61 and the counter electrode 62.

[0018] The perovskite layer 44 is an organic-inorganic hybrid compound. Specifically, the perovskite layer 44 is produced by reacting a compound composed of lead and a halogen element X (PbX2, where X = the halogen element) with methylammonium iodide (CH3NH3I; hereinafter, sometimes abbreviated as "MAI"). Specifically, a solution containing lead and the halogen element X (e.g., a solution of PbI2 in N,N-dimethylformamide) is infiltrated into the pores of the porous semiconductor 41, dried, and then immersed in a mixed solution of MAI, whereby crystals of the perovskite compound (CH3NH3PbI3 when X = I) that forms the perovskite layer 44 are rapidly produced. The halogen element X can be iodine, bromine, chlorine, or the like, and iodine, which has high morphological stability, is preferably used. In addition, halogen element X was converted into mixed cation-mixed halide (FAPbI3) using MABr and 0.2M lead bromide (PbBr2), and FAI and lead iodide (PbI2). 1-x (MAPbBr3) x ) may be used. In this case, for example, (FAPbI3) 0.85 (MAPbBr3) 0.15 etc. can be suitably used.

[0019] A hole transport material described later is used for the hole transport layer 5. For the photoelectrode 61, for example, an elemental metal or alloy of a metal such as gold, platinum, silver, or copper, or an oxide conductor such as fluorine-doped tin oxide (FTO) or tin-doped indium oxide (ITO) is used.

[0020] The counter electrode 62 is a carbon electrode. The counter electrode 62 of this embodiment contains graphite (an example of carbon) and carbon black (an example of carbon). The counter electrode 62 of this embodiment is a carbon electrode with reduced sheet resistance and improved conductivity, which is obtained by using a residue obtained by drying a carbon liquid 62a (see FIG. 4) in which graphite and carbon black are dispersed in a solvent 62b (an example of an alcohol-based solvent; see FIG. 4) that has low water absorption and low water penetration into the hole transport layer 5 and the perovskite layer 44.

[0021] Next, the principle of how solar cell 10 generates electricity will be described with reference to Figure 3. When light such as sunlight or room light is incident from the transparent substrate 21 side, this incident light passes through substrate 2 and blocking layer 3 without being absorbed much, and most of it reaches power generation layer 4. When the incident light that has reached power generation layer 4 is irradiated onto perovskite layer 44, this perovskite layer 44 absorbs the light energy and becomes excited. When this excitation raises the energy level of perovskite layer 44 to a predetermined level higher than the conduction band potential of the metal oxide that is the porous semiconductor 41, electrons are injected from perovskite layer 44 into porous semiconductor 41. The injected electrons pass through blocking layer 3 and are collected by photoelectrode 61.

[0022] Meanwhile, holes generated in the perovskite layer 44 reach the counter electrode 62 via the hole transport layer 5, where they recombine with electrons that have passed through the external load 7. In other words, a potential gradient is generated between the photoelectrode 61 and the counter electrode 62, and power can be supplied by connecting the external load 7 between the two electrodes. [Example]

[0023] [Solar cell fabrication procedure] <Example> Next, an example of the solar cell 10 according to this embodiment will be described. First, a manufacturing procedure for the solar cell 10 will be described with reference to FIG. 4. The solar cell 10 can be manufactured with reference to known techniques such as Michael Saliba et al., "Correction to 'How to Make over 20% Efficient Perovskite Solar Cells in Regular (nip) and Inverted (pin) Architectures," Chem. Mater., 2018, 30, 4193-4218.

[0024] First, a transparent conductive film 22 is formed on a transparent substrate 21 to prepare the substrate 2. The transparent conductive film 22 is laminated on the transparent substrate 21 by, for example, chemical vapor deposition (CVD) or sputtering. Next, laser scribing is performed to partially remove the transparent conductive film 22, forming recesses 221 for the insulating layer 31, followed by cleaning. Next, a blocking layer 3 is formed over the entire surface of the substrate 2 by atomic layer deposition (ALD) or spray pyrolysis (SPD). The blocking layer 3 is preferably formed as a dense TiO layer. Next, a porous semiconductor 41, which is a nanoparticle sintered layer, is formed near the center of the masked substrate 2 and blocking layer 3. The porous semiconductor 41 is preferably formed as a porous layer of TiO (p-TiO). This porous semiconductor 41 is formed by diluting nanoparticle paste with a solvent, applying it by spin coating at a rotation speed of 4000 rpm or more and 6000 rpm or less, drying it, and then removing the masking and heating it at a temperature of 450°C or more and 550°C or less to sinter it.

[0025] Next, for example, a solution of PbI2 in N,N-dimethylformamide is prepared and dropped onto the porous semiconductor 41. After that, the solution is permeated into the pores (p-TiO2) and excess solution is removed by spin coating at a rotation speed of, for example, 5000 rpm to 8000 rpm. The solution is then dried at a temperature of 60°C to 120°C (preferably 70°C to 90°C) to form a PbI2 layer.

[0026] The substrate 2, blocking layer 3, and porous semiconductor 41 permeated with lead iodide are immersed in an isopropyl alcohol solution of MAI (CH3NH3I) (2 mg / ml to 20 mg / ml) at 0°C to 80°C (preferably at room temperature) (MAI immersion method). PbI2 and MAI react to form a perovskite compound [(CH3NH3)PbI3(MAPbI3)] as a perovskite layer 44 inside and on the pores of the porous semiconductor 41. The porous semiconductor 41 is then rinsed with pure isopropyl alcohol and dried at 60°C to 120°C (preferably 70°C to 100°C). The mixed cation-mixed halide ((FAPbI3) 1-x (MAPbBr3) x)-based perovskite compounds can also be prepared in a similar manner.

[0027] The above fabrication procedure involves controlling the crystal growth of the perovskite compound that forms the perovskite layer 44 in two steps, but this can also be done in one step. For example, a perovskite ((CH3NH3)PbI3) solution is permeated into the pores of the porous semiconductor 41 by spin coating. Next, toluene is added dropwise during spinning to precipitate microcrystals and create a mirror-finished surface (poor solvent precipitation method).

[0028] The hole transport material according to this example (e.g., Spiro-OMeTAD) is prepared as a chlorobenzene solution at a concentration of 60 mg / ml to 90 mg / ml. The solution is dropped onto the perovskite layer 44, excess solution is removed by spin coating, and the solution is dried to form the hole transport layer 5. An additive such as TPFB may be added to the hole transport material. When TPFB is added, the TPFB content of the hole transport material is preferably 0.01 wt % to 100 wt %, and more preferably 0.1 wt % to 50 wt %. For example, the hole transport material according to this example is weighed out to 30 mM, and TPFB equivalent to 10 wt % of that is added. The hole transport layer 5 can be formed by dissolving these in chlorobenzene. Note that the thickness of the hole transport layer 5 in this example and Comparative Examples 1 to 3 described below is 200 nm.

[0029] The above steps from forming the PbI2 layer to forming the hole transport layer 5 are preferably carried out in a dry nitrogen atmosphere such as in a glove box. Finally, the electrode 6 is formed. The photoelectrode 61 is formed by adhering a thin film of gold or the like to the surface of the blocking layer 3 by vacuum deposition or the like.

[0030] As described above, the counter electrode 62 is a carbon electrode containing graphite and carbon black. In this embodiment, the counter electrode 62 is formed using a carbon liquid 62a in which graphite, carbon black, a resin binder, a stabilizer component, and the like (hereinafter referred to as the resin component) are dispersed in a solvent 62b. The carbon liquid 62a in this embodiment contains 5% to 20% by weight of graphite, 5% to 20% by weight of carbon black, 1.0% to 15% by weight of the resin component, and 45% to 89% by weight of the solvent 62b. More preferably, the carbon liquid 62a contains 10% to 20% by weight of graphite, 6% to 20% by weight of carbon black, 5% to 12% by weight of the resin component, and 48% to 79% by weight of the solvent 62b. The specific composition of the carbon liquid 62a used in this example is 17.5% by weight of graphite, 7.0% by weight of carbon black, 10.5% by weight of resin component, and 65.0% by weight of solvent 62b (total 100% by weight).

[0031] The resin component is preferably a resin binder such as polyvinylidene fluoride (PVDF), polyvinyl alcohol, polyvinyl acetal, acrylic resin, polyvinyl acetate, polyvinyl chloride, polystyrene, polyvinyl ether, polyvinylpyrrolidone (PVP), styrene-butadiene rubber (SBR), or carboxymethyl cellulose, and a binder that dissolves in the solvent 62b can be appropriately selected and used. The solvent 62b is an alcohol-based solvent that has low absorption of moisture in the air, and is preferably an alcohol-based solvent such as isopropyl alcohol, isobutyl alcohol, tert-butyl alcohol, 1-pentanol, isoamyl alcohol, or cyclohexanol, and can be appropriately selected and used from those that do not dissolve the hole transport layer 5 and the perovskite layer 44.

[0032] The carbon solution 62a is prepared by dispersing graphite, carbon black, and a resin component in a solvent 62b. Dispersion can be performed in an environment where the solvent 62b is less likely to absorb moisture from the air. For example, the temperature and humidity can be appropriately adjusted using an air conditioning system. Examples of suitable equipment for dispersion include planetary mixers, kneaders, extrusion mixers, thin-film rotary high-speed mixers, rolls, and media-agitation mills. The graphite, carbon black, and resin components can be dispersed by sequentially adding each component, or all components can be dispersed at once. The viscosity of the carbon solution 62a obtained in this manner, if between 600 cps and 2000 cps, is considered optimal for the anode electrode formation process described below.

[0033] Specifically, the dispersion method involves first mixing a solution of the resin component in a solvent 62b (e.g., isobutyl alcohol), carbon black, and graphite. Then, a dispersion process is performed using a triple roll to obtain the carbon liquid 62a. The dispersion process can be continued until the desired viscosity is achieved.

[0034] The anode forming process, which is a method for forming the counter electrode 62, will be described below. In the anode forming process, first, the carbon liquid 62a described above is applied onto the hole transport layer 5. Then, a coater 70 is moved in the direction A indicated by the arrow in FIG. 4 to spread and coat the carbon liquid 62a onto the hole transport layer 5. The carbon liquid 62a is then dried to evaporate the solvent 62b. The solvent 62b can be evaporated, for example, by heating at 80°C for 30 minutes. This dries the residual graphite, carbon black, and resin components, resulting in a carbon film.

[0035] If the sheet resistance (thickness of the carbon film) after the carbon film is formed is not equal to or less than the desired value, this indicates that the carbon film is too thin. Therefore, it is necessary to repeatedly apply and dry the carbon liquid 62a to thicken the carbon film until the sheet resistance reaches the desired value. In this example, however, the gap between the coater 70 and the hole transport layer 5 is set relatively large, and the carbon film is formed once to obtain a counter electrode 62 having the desired thickness of 20 μm. The counter electrode 62 in this example is a single layer. Even if the counter electrode 62 is obtained by applying and drying multiple times, it is still a single layer if the carbon liquid 62a has the same composition ratio.

[0036] <Comparative Example 1> The solar cell of Comparative Example 1 differs from solar cell 10 of this example in that the solvent of carbonaceous liquid 62a is water. The other configurations and manufacturing methods are the same as those of solar cell 10 of this example.

[0037] <Comparative Example 2> The solar cell of Comparative Example 2 differs from the solar cell 10 of this example in that the solvent of the carbonaceous liquid 62a is propylene glycol monomethyl ether (a solvent that dissolves the hole transport layer 5 and the perovskite layer 44). The other configurations and manufacturing methods are the same as those of the solar cell 10 of this example.

[0038] <Comparative Example 3> The solar cell of Comparative Example 3 differs from solar cell 10 of this example in that the material of the counter electrode is a gold electrode. The gold electrode is formed by vapor deposition. The other configurations are the same as those of solar cell 10 of this example.

[0039] The materials, film-forming methods, and blending ratios of the counter electrode 62 and the carbonaceous liquid 62a in the example and comparative examples 1 to 3 are shown in Table 1 below. Note that in the example, comparative example 1, and comparative example 2, the total blending ratio of each component in the carbonaceous liquid 62a is 100 wt %.

[0040] [Table 1]

[0041] The moisture content in Table 1 refers to the amount of water contained in the carbonaceous liquid 62a. As a result, the moisture content of the solar cell 10 in the example and comparative example 2 is 5% or less, which means low water absorption, while the moisture content of comparative example 1 is 100%.

[0042] For the solar cell 10 of Example and Comparative Examples 1 to 3 manufactured by the above-described manufacturing method, the solubility in the hole transport layer 5, the solubility in the perovskite layer 44, the sheet resistance of the counter electrode, and the photoelectric conversion efficiency of the solar cell were measured. The sheet resistance was measured in accordance with JIS K7194 "Test method for resistivity of conductive plastics by the four-probe method." The photoelectric conversion efficiency of the solar cell 10 is expressed as a relative value (hereinafter also referred to as the relative value of photoelectric conversion efficiency) when the photoelectric conversion efficiency of Comparative Example 3 is set to 1. The measurement results are shown in Table 2 below.

[0043] [Table 2]

[0044] As can be seen from Table 2, the solar cell 10 of this example is insoluble in both the hole transport layer 5 and the perovskite layer 44, and the water in the solvent 62b hardly penetrates into the hole transport layer 5 or the perovskite layer 44. Furthermore, because the counter electrode 62 has a film thickness of 20 μm, the solar cell 10 of this example is as thin and flexible as a solar cell having a gold electrode (Comparative Example 3). Furthermore, the photoelectric conversion efficiency is 95% of that of a gold electrode, and the solar cell 10 of this example has a photoelectric conversion efficiency comparable to that of a solar cell having a gold electrode.

[0045] Generally, the sheet resistance of the counter electrode in a solar cell is preferably 20 Ω / sq or less, and more preferably 10 Ω / sq or less. As shown in Table 2, the sheet resistance of the counter electrode 62 of the solar cell 10 of this example is 9 Ω / sq, which satisfies the more desirable sheet resistance requirement. Furthermore, the counter electrode 62 of the solar cell 10 of this example is made of carbon, which is more cost-effective than a gold electrode. Therefore, the solar cell 10 of this example is practical in all respects: solubility in the hole transport layer 5 and perovskite layer 44, photoelectric conversion efficiency, sheet resistance, and cost.

[0046] In the solar cell of Comparative Example 1, the sheet resistance of the counter electrode was 10 Ω / sq, and the counter electrode was insoluble in the hole transport layer 5. However, with regard to the solubility in the perovskite layer 44, the perovskite layer 44 was discolored, and moisture in the solvent penetrated into the perovskite layer 44. Furthermore, the relative value of the photoelectric conversion efficiency was 0.001, so the solar cell of Comparative Example 1 hardly generated any electricity. Therefore, although the solar cell of Comparative Example 1 had a low sheet resistance, it was not practical due to the high water absorption of the perovskite layer 44 and the low photoelectric conversion efficiency.

[0047] In the solar cell of Comparative Example 2, the sheet resistance of the counter electrode was 10 Ω / sq. However, the solubility in both the hole transport layer 5 and the perovskite layer 44 was high, and the propylene glycol monomethyl ether itself penetrated into the hole transport layer 5 and the perovskite layer 44. Furthermore, since the relative value of the photoelectric conversion efficiency could not be measured, it is believed that the solar cell of Comparative Example 2 did not generate any electricity. Therefore, although the solar cell of Comparative Example 2 had a low sheet resistance, it was not practical due to the high water absorption of the hole transport layer 5 and the perovskite layer 44 and the low photoelectric conversion efficiency.

[0048] In the solar cell of Comparative Example 3, the sheet resistance of the counter electrode is 0.6 Ω / sq, and the relative value of the photoelectric conversion efficiency is 1. This shows that the solar cell of Comparative Example 3 is excellent in both sheet resistance and photoelectric conversion efficiency. However, since the counter electrode is made of gold, which is expensive, it is not practical from the standpoint of cost.

[0049] [Summary of the above embodiment] Hereinafter, the perovskite solar cell (10) described in the above embodiment will be considered to have the following configuration.

[0050] <1> One embodiment of the perovskite solar cell (10) is a perovskite solar cell (10) having an electrode layer (62) disposed adjacent to a hole transport layer (5), the electrode layer (62) including a residue obtained by drying a carbonaceous liquid (62a) dispersed in an alcohol-based solvent (62b).

[0051] According to this embodiment, the alcohol-based solvent (62b) has low moisture absorption (water absorption) for air, so that the absorption of moisture from air is unlikely to occur when dispersing carbon. Therefore, in the carbon solution (62a) using the alcohol-based solvent (62b), the moisture in the alcohol-based solvent (62b) is prevented from penetrating into the hole transport layer (5) or the perovskite layer (44). As a result, even if the electrode layer (62) contains a residue from drying the carbon solution (62a), a perovskite solar cell (10) can be obtained that has low sheet resistance and photoelectric conversion efficiency comparable to that of a gold electrode.

[0052] <2> the above <1> In the perovskite solar cell (10) described above, the electrode layer (62) is preferably a single layer.

[0053] If the electrode layer 62 is a single layer, only one type of carbon liquid 62a is required to be applied to form the electrode layer 62, thereby reducing the number of manufacturing steps and the cost.

[0054] <3> the above <1> or <2> In the perovskite solar cell (10) described above, the electrode layer (62) is an anode, and it is preferable that the sheet resistance of the electrode layer (62) is 10 Ω / sq or less.

[0055] Generally, the sheet resistance of the electrode layer in a perovskite solar cell is preferably 20 Ω / sq or less, and more preferably 10 Ω / sq or less. Therefore, in this embodiment, the perovskite solar cell (10) having an electrode layer (62) with a resistance of 10 Ω / sq or less is practical in terms of sheet resistance.

[0056] <4> the above <1> from <3> The carbon liquid (62a) used to form the electrode layer (62) of the perovskite solar cell (10) described in any one of the above preferably has a composition of 5% by weight to 20% by weight of graphite, 5% by weight to 20% by weight of carbon black, 1.0% by weight to 15% by weight of a resin component, and 45% by weight to 89% by weight of an alcohol-based solvent (62b).

[0057] If the carbon solution (62a) used to form the electrode layer (62) of the perovskite solar cell (10) has such a composition, it is possible to obtain a perovskite solar cell (10) having an electrode layer (62) containing carbon that has a low sheet resistance and a photoelectric conversion efficiency comparable to that of a gold electrode. [Industrial Applicability]

[0058] The present disclosure is applicable to perovskite solar cells and carbonaceous materials. [Explanation of symbols]

[0059] 5: hole transport layer, 10: perovskite solar cell, 62: counter electrode (electrode layer, anode), 62a: carbon liquid, 62b: solvent (alcohol-based solvent)

Claims

1. 1. A perovskite solar cell having an electrode layer disposed adjacent to a hole transport layer, The electrode layer comprises a residue obtained by drying a carbon liquid dispersed in an alcohol-based solvent.

2. The perovskite solar cell according to claim 1 , wherein the electrode layer is a single layer.

3. 2. The perovskite solar cell according to claim 1, wherein the electrode layer is an anode and the sheet resistance of the electrode layer is 10 Ω / sq or less.

4. A carbon liquid used to form the electrode layer of the perovskite solar cell according to any one of claims 1 to 3, A carbon liquid having a composition of 5% by weight or more and 20% by weight or less of graphite, 5% by weight or more and 20% by weight or less of carbon black, 1.0% by weight or more and 15% by weight or less of a resin component, and 45% by weight or more and 89% by weight or less of the alcohol-based solvent.

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