Conductive body and method for manufacturing the same

Abstract

A conductor includes a conductive structure including a conductive carbon material (11) and having a predetermined shape, and a dopant (30) that generates electric charges in the carbon material. The dopant includes a triflate salt composed of a trivalent ion of a lanthanoid element and a triflate anion.

Description

[0001] Cross-reference of related applications

[0002] This application is based on Japanese Patent Application No. 2020-113133, filed on June 30, 2020, the contents of which are incorporated herein by reference. Technical Field

[0003] This invention relates to a conductive material and its manufacturing method. Background Technology

[0004] Patent Document 1 discloses a conductive film formed by contacting chloroauric acid, a dopant, with the surface of a CNT-containing film, which is a film containing carbon nanotubes (CNTs). In this conductive film, the thin-film resistance of the CNT-containing film is reduced and the conductivity is increased by the dopant. Thin-film resistance is also known as surface resistivity.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2015-210955 Summary of the Invention

[0008] However, the inventors have discovered that the performance of the existing conductive film deteriorates and the effect of improving conductivity disappears under high temperature and high humidity conditions.

[0009] Furthermore, this is not limited to conductive films containing CNTs and chloroauric acid. Even conductive materials containing carbon-based conductive structures and chloroauric acid will experience performance degradation under high temperature and high humidity conditions.

[0010] The purpose of this invention is to provide a conductor whose conductivity can be improved by doping while suppressing performance degradation under high temperature and high humidity conditions, and a method for manufacturing the same.

[0011] To achieve the above objectives, according to one aspect of the present invention:

[0012] A type of conductor,

[0013] It possesses: a conductive structure containing conductive carbon material and formed into a specified shape.

[0014] And dopants that generate an electric charge on the carbon material,

[0015] The dopant contains trifluoromethanesulfonate, which is composed of trivalent lanthanide ions and trifluoromethanesulfonate anions.

[0016] Therefore, it is possible to improve the conductivity of conductive structures by using dopants, while suppressing performance degradation under high temperature and high humidity conditions.

[0017] Furthermore, according to another aspect of the present invention:

[0018] A method for manufacturing a conductor, comprising:

[0019] Prepare a conductive structure containing conductive carbon material and forming it into a specified shape.

[0020] Prepare a solution containing a solute and a solvent, using a dopant that generates an electric charge on the carbon material as the solute.

[0021] The solution is then applied to the conductive structure.

[0022] After the solution adheres, the solvent is removed from the conductive structure.

[0023] In preparing the solution, a solute containing a trifluoromethanesulfonate salt composed of trivalent lanthanide ions and trifluoromethanesulfonate anions is used as the solute.

[0024] Therefore, it is possible to improve the conductivity of conductive structures by using dopants, while suppressing performance degradation under high temperature and high humidity conditions.

[0025] Furthermore, the reference symbols in parentheses attached to each constituent element indicate an example of the correspondence between that constituent element and the specific constituent elements described in the embodiments described later. Attached Figure Description

[0026] [ Figure 1 [A perspective view of the transparent conductive film in the embodiment.]

[0027] [ Figure 2 A conceptual diagram of CNTs and dopants in the implementation method.

[0028] [ Figure 3 [This represents the chemical structure of an anhydrous trifluoromethanesulfonate, which is composed of a trivalent cerium ion and a trifluoromethanesulfonate anion.]

[0029] [ Figure 4 [ ] represents a flowchart of the method for manufacturing the conductor in the embodiment.

[0030] [ Figure 5 Conceptual diagram of previous positive charge-donating dopants and CNTs.

[0031] [ Figure 6 Conceptual diagram of previous negative charge-donating dopants and CNTs.

[0032] [ Figure 7 [A three-dimensional view of the test specimen of Example 1 before solution adhesion.]

[0033] [ Figure 8 [A three-dimensional view of the test specimen of Example 1 in a solution-attached state.]

[0034] [ Figure 9 The graphs represent the durability evaluation test results of Example 1 and Comparative Example 1, respectively.

[0035] [ Figure 10 The figure shows the chemical state analysis results of the dopant before and after the durability evaluation test of Comparative Example 1.

[0036] [ Figure 11 [ ] shows the chemical structure of the trifluoromethanesulfonate used in Comparative Example 2.

[0037] [ Figure 12 [ ] shows the chemical structure of the trifluoromethanesulfonate used in Comparative Example 3.

[0038] [ Figure 13 The graphs represent the durability evaluation test results of Example 2, Comparative Example 2, and Comparative Example 3, respectively.

[0039] [ Figure 14 The graph shows the relationship between dopant concentration and thin film resistance change rate in Example 3.

[0040] [ Figure 15 The graph shows the relationship between dopant concentration and the rate of change of thin film resistance in Comparative Example 4. Detailed Implementation

[0041] The following describes embodiments of the present invention. The conductor of this embodiment comprises: a conductive structure containing a conductive carbon material, and a dopant that generates an electric charge on the carbon material.

[0042] Nanomaterials are used as conductive carbon materials. Nanomaterials are carbon materials whose structure is controlled at the nanoscale. Nanoscale refers to dimensions below 1000 nm, but also includes dimensions below 1 nm. Nanomaterials include materials whose smallest dimension is greater than 1 nm and less than 1000 nm. Examples of nanomaterials include CNTs (carbon nanotubes), CNBs (carbon nanorods), and graphene. CNTs, CNBs, and graphene primarily have six-membered ring structures. Alternatively, conductive carbon materials other than nanomaterials can also be used as conductive carbon materials.

[0043] A conductive structure is an object that is electrically conductive and formed into a prescribed shape. Examples of conductive structures include... Figure 1 The transparent conductive film 10 shown is a film in which carbon material (e.g., CNT) is dispersed and shaped into a film form. The transparent conductive film 10 has desired visible light transmittance and desired conductivity.

[0044] The transparent conductive film 10 is supported by a transparent substrate 20. The substrate 20 may be made of a synthetic resin material (e.g., PET) or an inorganic material (e.g., quartz glass). Alternatively, the transparent conductive film 10 may not be supported by a substrate 20.

[0045] The transparent conductive film 10 is used as a transparent heater. This transparent heater is used to ensure the functionality of automotive sensors or vehicle windshields. When icing or fogging occurs on the sensor or windshield, the transparent heater heats the sensor or windshield, thereby eliminating the ice or fog.

[0046] Conductive structures can also be opaque conductive films. Furthermore, the shape of a conductive structure doesn't have to be that of a film; it can be the shape of a line.

[0047] The dopant is dispersed on the conductive structure. The dopant is a substance that increases the electrical charge present in the carbon material. In this embodiment, the dopant is a positive charge-donating dopant (i.e., a p-type dopant) that imparts a positive charge to the carbon material.

[0048] exist Figure 2 The image shows CNT11 as an example of a carbon material and dopant 30. For example... Figure 2 As shown, dopant 30 is in contact with the surface of CNT11. Thus, the dopant is in contact with the carbon material while existing on the outside of it. Alternatively, the dopant can also be in contact with the carbon material while existing inside it.

[0049] In this embodiment, the dopant contains a trifluoromethanesulfonate composed of a trivalent lanthanide ion and a trifluoromethanesulfonate anion. If the dopant is primarily composed of this trifluoromethanesulfonate, it may also contain other compounds. Lanthanides are elements with atomic numbers 57 to 71. Lanthanides include Ce (i.e., cerium). The chemical formula of the trifluoromethanesulfonate anion is CF3SO3. - .

[0050] Figure 3 The chemical structure of anhydrous trifluoromethanesulfonate, consisting of a trivalent cerium ion and a trifluoromethanesulfonate anion, is shown. This trifluoromethanesulfonate is represented as anhydrous cerium(III) trifluoromethanesulfonate, anhydrous Ce(III)CF3SO3, or anhydrous Ce(III)TfO.

[0051] Next, the manufacturing method of the conductor with the above structure will be described. The manufacturing method of the conductor is as follows: Figure 4 As shown, the process includes step S1 of preparing the structure, step S2 of preparing the solution, step S3 of attaching the solution, and step S4 of removing the solvent.

[0052] In step S1 of preparing the structure, a conductive structure containing conductive carbon material is prepared.

[0053] In step S2, a solution containing a solute (as a dopant) and a solvent is prepared. In the solution, the solute dissolves in the solvent. The solute is a substance containing a trifluoromethanesulfonate salt composed of a trivalent lanthanide ion and a trifluoromethanesulfonate anion. The solvent can be an organic solvent such as isopropanol, ethanol, THF, hexane, dichloroethane, diethylene glycol diethyl ether, acetone, NMP, or ethyl acetate. The concentration of the solution prepared at this stage is sufficient for the dopant to bond with the carbon material.

[0054] Either the process S1 of preparing the structure or the process S2 of preparing the solution can be performed first or simultaneously.

[0055] After steps S1 (preparing the structure) and S2 (preparing the solution), step S3 (attaching the solution) is performed. In step S3, the solution is attached to the conductive structure. Methods for attaching the solution include coating, spraying, and immersing the conductive structure in the solution. When a membrane is used as the conductive structure, the solution adheres to the surface of the membrane. Alternatively, the solution can be attached to the interior of the membrane by immersing it inside.

[0056] After the solution is applied in step S3, a solvent removal step S4 is performed. In step S4, the conductive structure with the solution attached is dried. At this time, the conductive structure is heated to a temperature higher than the boiling point of the solvent. This removes the solvent from the conductive structure with the solution attached. The above operation is used to manufacture a conductive material.

[0057] Here, we will explain the previous dopants. Figure 5 , 6 The image shows CNT11 as a carbon material and conventional dopants 41 and 42. (Example) Figure 5 As shown, the positive charge-donating dopant 41 gains electrons from CNT11. Thus, CNT11 is endowed with a positive charge. Figure 6 As shown, the negative charge-donating dopant 42 transfers electrons to CNT11. Thus, CNT11 is endowed with a negative charge. In this way, conventional dopant 41 and 42 impart charge to the carbon material through electron donation and acceptance with it. At this time, excess charge is generated in dopant 41 and 42.

[0058] As described in the embodiments below, in a conductor using chloroauric acid as a positive charge-donating dopant, an effect of increased conductivity due to the dopant can be obtained. However, the inventors have discovered that when the conductor is exposed to a high-temperature and high-humidity environment, the performance of the conductor deteriorates, and the effect of increased conductivity disappears. It can be assumed that the reason for the deterioration of the conductor performance is that, in a high-temperature and high-humidity environment, chloroauric acid with excess charge reacts with water.

[0059] In contrast, the dopant in this embodiment contains a trifluoromethanesulfonate salt composed of a trivalent lanthanide ion and a trifluoromethanesulfonate anion. For example... Figure 2 As shown, the dopant is highly polarized. Therefore, an electrostatic attraction is generated on the carbon material through the polarized dopant and the carbon material. The carbon material is in a polarized state at this time. Thus, in this embodiment, the dopant electrostatically imparts a charge to the carbon material through its polarization without transferring charge (i.e., electrons) with the carbon material. Therefore, the generation of excess charge in the dopant is suppressed.

[0060] Therefore, according to the conductor of this embodiment, the conductivity of the conductive structure is improved by generating charges on the carbon material using dopants. Furthermore, since the generation of excess charges is suppressed, the performance degradation of the conductor can be suppressed under high temperature and high humidity environments, and the improved conductivity effect can be maintained.

[0061] The lanthanide element in the above-mentioned dopant is preferably cerium, as described in the examples below. Trifluoromethanesulfonate, which is composed of cerium trivalent ions and trifluoromethanesulfonate anions, is considered to be able to generate charges in carbon materials due to the strong polarization and high electron attraction of the dopant.

[0062] However, the main reason for the high electron attraction of dopants can be attributed to the electron density of the cation. It can be assumed that, similar to Ce, trifluoromethanesulfonates of elements with electrons in their f and d orbitals exhibit high electron attraction. Therefore, it can be assumed that trifluoromethanesulfonates of lanthanides other than Ce, with electronic states similar to Ce, also possess high electron attraction and can achieve the same effect as Ce.

[0063] Furthermore, the present invention is not limited to the embodiments described above, and can be appropriately modified, including various variations and modifications within the same range. Also, in the above embodiments, the elements constituting the embodiments are not necessarily essential, except where specifically stated as necessary or clearly considered necessary in principle. Furthermore, in the above embodiments, when referring to the number, value, quantity, range, etc., of the constituent elements of the embodiments, the number is not limited to that specific number, except where specifically stated as necessary or clearly defined as a specific number in principle. Furthermore, in the above embodiments, when referring to the material, shape, positional relationship, etc., of the constituent elements, the material, shape, positional relationship, etc., are not limited to that material, shape, positional relationship, except where specifically stated or defined as a specific material, shape, positional relationship in principle.

[0064] Example

[0065] (Example 1)

[0066] <Dopant Treatment>

[0067] like Figure 7 As shown, the inventors prepared a test specimen 22 on a quartz substrate 21 in which a CNT film 12 containing CNTs was formed. The CNT film 12 is a film formed by dispersing CNTs. The diameter of the CNTs used is in the range of 0.7 to 3 nm.

[0068] The inventors treated the prepared test specimen 22 with a dopant. In the dopant treatment, a solution was prepared in which anhydrous cerium trifluoromethanesulfonate (III) was dissolved as a solute relative to IPA (i.e., isopropanol) as a solvent. The IPA used was 19516 IPA manufactured by Sigma-Aldrich. The anhydrous cerium trifluoromethanesulfonate (III) used was Cetriflate abcr GmbH, PubChem SID: 316470470, Purchased Chemical: AB255546. The concentration of the prepared solution was 10 mM. Then, the inventors used a pipette to drop the prepared solution onto the surface of the CNT film 12. Thus, as... Figure 8 As shown, solution droplets 31 were attached to the surface of CNT film 12. At this time, the inventors applied 300 μl of solution to a 2 cm × 2 cm test specimen. This state was maintained for 30 seconds. Then, the inventors removed the solution from the surface of the test specimen 22 by blowing air. Furthermore, the inventors dried the test specimen 22 to remove the solvent. The drying conditions were 100°C at atmospheric temperature for 10 minutes.

[0069] <Evaluation of Improved Conductivity>

[0070] The inventors measured the film resistance of the CNT film 12 before and after doping using an eddy current type film resistance meter. The unit of film resistance is Ω□. Then, using the film resistance value before doping, the film resistance value after doping, and the following formula, the inventors calculated the rate of change of film resistance relative to the film resistance before doping.

[0071] Thin film resistivity change rate (%) = (Rs2 - Rs1) / Rs1 × 100

[0072] In this formula, Rs1 is the thin film resistance before doping, and Rs2 is the thin film resistance after doping.

[0073] <Durability Evaluation Test>

[0074] The inventors maintained the dopant-treated test specimens in a constant temperature and humidity chamber for 1000 hours, ensuring a high temperature and humidity environment. The chamber was set to 85°C and 85% RH. At regular intervals, the inventors measured the film resistance of the CNT film using an eddy current type film resistance meter. Furthermore, the inventors calculated the rate of change of film resistance relative to the film resistance before dopant treatment, as described above.

[0075] (Comparative Example 1)

[0076] The inventors used AuCl4H·3H2O (i.e., chloroauric acid) as the solute and performed doping treatment in the same manner as in Example 1. The chloroauric acid used was Tetrachloroauric(III) acidtrihydrate 99.5% for analysis EMSURE(R) manufactured by Sigma-Aldrich. CAS 16961-25-4, EC 240-948-4, chemical formula AuCl4H*3H2O. The concentration of the solution used was 20 mM.

[0077] In addition, the inventors measured the thin film resistance before and after dopant treatment in the same manner as in Example 1. The rate of change of thin film resistance was calculated based on the results. Furthermore, the inventors conducted a durability evaluation test in the same manner as in Example 1. The inventors measured the thin film resistance of the CNT film at regular intervals. The inventors calculated the rate of change of thin film resistance based on these results.

[0078] In addition, the inventors used X-ray photoelectron spectrometry to analyze the chemical state of the dopant before and after the durability evaluation test. The durability evaluation test refers to the period after 1000 hours of storage in a constant temperature and humidity chamber.

[0079] Figure 9These are the results of the durability evaluation tests for Example 1 and Comparative Example 1, respectively. Figure 9 The vertical axis of the graph represents the rate of change of thin film resistance relative to the thin film resistance before doping treatment. Figure 9 The horizontal axis of the graph represents the time spent exposed to a high-temperature and high-humidity environment. The rate of change of thin film resistance at 0 hours is the rate of change of thin film resistance after dopant treatment.

[0080] like Figure 9 As shown, in Example 1, the rate of change of film resistance after dopant treatment is less than -40%. A negative rate of change of film resistance means that the film resistance has decreased compared to the film resistance before dopant treatment. Furthermore, the absolute value of the rate of change of film resistance is greater than 40%. Therefore, in Example 1, the reduction rate of film resistance is large, and the effect of improving conductivity is significant. Moreover, even with prolonged exposure to a high-temperature and high-humidity environment, the rate of change of film resistance remains nearly constant. Thus, it is confirmed that in Example 1, performance does not deteriorate under high-temperature and high-humidity conditions.

[0081] like Figure 9 As shown, in Comparative Example 1, similar to Example 1, the rate of change of film resistance after dopant treatment was negative and the absolute value was large, thus resulting in a high degree of conductivity improvement. However, in Comparative Example 1, the rate of change of film resistance increased with the passage of time exposed to a high-temperature and high-humidity environment. After 1000 hours, the rate of change of film resistance approached 0%. Thus, it was confirmed that in Comparative Example 1, performance deteriorated and the conductivity improvement effect disappeared under high-temperature and high-humidity conditions.

[0082] Figure 10 These are the chemical state analysis results of the dopant before and after the durability evaluation test of Comparative Example 1. For example... Figure 10 As shown, it was confirmed that after the experiment, compared with before the experiment, chloroauric acid decreased and gold increased. That is, it was confirmed that the gold content increased from Au... + The change to Au. This is because AuCl4 - Hydrolysis occurred, producing hydrochloric acid and hypochlorous acid. According to... Figure 10 The results suggest that in Comparative Example 1, under high temperature and high humidity conditions, chloroauric acid was reduced from ionized compounds to gold, thus reducing the charge of CNTs and degrading the performance of the CNT membrane.

[0083] Furthermore, similar to Comparative Example 1, it was confirmed that in the test specimen using chloroauric acid as a dopant, performance deteriorated at a high temperature of 120°C, and the effect of improved conductivity disappeared. On the other hand, similar to Example 1, it was confirmed that in the test specimen using anhydrous cerium trifluoromethanesulfonate (III), performance did not deteriorate at a high temperature of 120°C.

[0084] (Example 2)

[0085] In Example 2, the inventors used the same anhydrous cerium(III) trifluoromethanesulfonate as the solute as in Example 1. Using a different test specimen than in Example 1, the inventors performed dopant treatment, measured the thin film resistance before and after dopant treatment, and measured the thin film resistance at regular intervals during the durability evaluation test, all in the same manner as in Example 1. The inventors then calculated the rate of change of thin film resistance relative to the thin film resistance before dopant treatment. However, in Example 2, the film was kept inside a constant temperature and humidity chamber for 216 hours.

[0086] In addition, the inventors used X-ray photoelectron spectrometry to analyze the chemical state of the dopant before and after the durability evaluation test. The durability evaluation test refers to the period after 216 hours of storage in a constant temperature and humidity chamber.

[0087] (Comparative Example 2)

[0088] In Comparative Example 2, the inventors used [a specific ingredient] as the solute. Figure 11 The anhydrous cerium trifluoromethanesulfonate (IV) shown is an anhydrous cerium tetravalent ion trifluoromethanesulfonate, represented as anhydrous Ce(IV)TfO.

[0089] The inventors performed the same dopant treatment, thin film resistance measurements before and after dopant treatment, and thin film resistance measurements at regular intervals during the durability evaluation test as in Example 2. Then, the inventors calculated the rate of change of thin film resistance relative to the thin film resistance before dopant treatment. Furthermore, the inventors performed the same chemical state analysis of the dopant before and after the durability evaluation test as in Example 2.

[0090] (Comparative Example 3)

[0091] In Comparative Example 3, the inventors used a compound named cerium(III) trifluoromethanesulfonate hydrate as the solute. Figure 12 As shown, cerium(III) trifluoromethanesulfonate hydrate is a trifluoromethanesulfonate containing the trivalent ion of cerium with water molecules, denoted as Ce(III)TfO hydrate. Additionally, in Figure 12 In the diagram, only trivalent ions of cerium are shown.

[0092] The inventors performed the same dopant treatment, thin film resistance measurements before and after dopant treatment, and thin film resistance measurements at regular intervals during the durability evaluation test as in Example 2. Then, the inventors calculated the rate of change of thin film resistance relative to the thin film resistance before dopant treatment. Furthermore, the inventors also performed a chemical state analysis of the dopant before and after the durability evaluation test, similar to Example 2.

[0093] Figure 13These are the results of the durability evaluation tests for Example 2, Comparative Example 2, and Comparative Example 3, respectively. Figure 13 The vertical axis of the graph represents the rate of change of thin film resistance relative to the thin film resistance before doping treatment. Figure 13 The horizontal axis of the graph represents the time spent exposed to a high-temperature and high-humidity environment. The rate of change of thin film resistance at 0 hours is the rate of change of thin film resistance after dopant treatment.

[0094] like Figure 13 As shown, in Example 2, similar to Example 1, the reduction rate of film resistance at 0 hours is relatively large. Furthermore, even with prolonged exposure to a high-temperature and high-humidity environment, the rate of change in film resistance remains nearly constant. Thus, it is confirmed that in Example 2, performance does not deteriorate even when exposed to a high-temperature and high-humidity environment.

[0095] In both Comparative Examples 2 and 3, the rate of change of film resistance at 0 hours was less than -40%. This indicates a high degree of improvement in conductivity. However, compared to Example 2, in the initial stage within 24 hours after the start of the durability evaluation test, the increase in the rate of change of film resistance in both Comparative Examples 2 and 3 was significantly larger. An increased rate of change of film resistance means increased film resistance and decreased conductivity. Thus, in Comparative Examples 2 and 3, performance degradation occurred in the initial stage.

[0096] [Table 1]

[0097] Name of reagent Before durability After durability Example 2 Anhydrous Ce(III)TfO III III Comparative Example 2 Anhydrous Ce(IV)TfO IV III Comparative Example 3 Ce(III)TfO hydrate IV>>III IV>III

[0098] Table 1 shows the results of the chemical state analysis of the dopants before and after the durability evaluation tests for Examples 2, Comparative Examples 2 and 3. In the dopant of Comparative Example 2, after the test, the proportion of Ce(IV) decreased and the proportion of Ce(III) increased compared with before the test.

[0099] The reagent used as a dopant in Comparative Example 3 was cerium(III) trifluoromethanesulfonate hydrate. However, in the dopant before the test, there was a large amount of Ce(IV) compared to Ce(III). Therefore, the dopant used in Comparative Example 3 contained more trifluoromethanesulfonate composed of tetravalent cerium ions and trifluoromethanesulfonate anions than trifluoromethanesulfonate composed of trivalent cerium ions and trifluoromethanesulfonate anions. In the dopant after the test, the proportion of Ce(IV) decreased and the proportion of Ce(III) increased compared to before the test. However, even after the test, there was more Ce(IV) than Ce(III) in the dopant.

[0100] As described above, both Ce(III) and Ce(IV) function as dopants. However, considering the redox potential, Ce(III) is more stable than Ce(IV). Therefore, in the dopants of Comparative Examples 2 and 3, Ce(IV) initially transforms into Ce(III). This is considered to be the reason for the initial degradation in Comparative Examples 2 and 3.

[0101] On the other hand, in the dopant of Example 2, the proportion of Ce(III) remained unchanged before and after the test. Therefore, no initial degradation occurred in the dopant of Example 2. The performance of the dopant remained stable even when exposed to high temperature and high humidity environments.

[0102] Furthermore, it is known that Ce(IV) is generally more stable than Ce(III) in Ce oxides. However, as mentioned above, Ce(III) is more stable than Ce(IV) in Ce trifluoromethanesulfonates. Therefore, when Ce trifluoromethanesulfonates are used as dopants, Ce can be a trivalent ion.

[0103] Depend on Figure 13 The results and those in Table 1 show that it is preferable to use a substance containing more trivalent cerium ions and trifluoromethanesulfonate anions than a trifluoromethanesulfonate composed of tetravalent cerium ions and trifluoromethanesulfonate anions as a dopant. Furthermore, it is even more preferable to use a trifluoromethanesulfonate containing trivalent cerium ions that does not contain tetravalent ions as a dopant. In other words, it is even more preferable to use a trifluoromethanesulfonate composed of trivalent cerium ions and trifluoromethanesulfonate anions that does not contain water molecules as a dopant.

[0104] (Example 3)

[0105] In Example 3, the inventors prepared three solutions with the same solute and solvent as in Example 1, and solute concentrations of 1, 5, and 10 mM. Then, using these three solutions, the inventors treated the test specimens with dopant in the same manner as in Example 1. Furthermore, the inventors measured the thin film resistance before and after the dopant treatment. Using these results, the inventors calculated the rate of change of thin film resistance relative to the thin film resistance before dopant treatment.

[0106] (Comparative Example 4)

[0107] In Comparative Example 4, the inventors prepared three solutions with anhydrous potassium trifluoromethanesulfonate (III) (i.e., potassium trifluoromethanesulfonate) as the solute and solute concentrations of 1, 5, and 10 mM. The anhydrous potassium trifluoromethanesulfonate (III) used was Sigma-Aldrich 422843. Furthermore, the inventors used these three solutions to perform doping treatment on the test specimens in the same manner as in Example 1. In addition, the inventors measured the thin film resistance before and after the doping treatment. Using these results, the inventors calculated the rate of change of thin film resistance relative to the thin film resistance before doping treatment.

[0108] Figure 14 The results are from Example 3. The film resistance change rate when the concentration of anhydrous cerium trifluoromethanesulfonate (III) is 1 mM is less than -40%. That is, the reduction rate of film resistance at this concentration is greater than 40%. The film resistance change rate when the concentrations of anhydrous cerium trifluoromethanesulfonate (III) are 5 and 10 mM is less than -60%. That is, the reduction rate of film resistance at these concentrations is greater than 60%.

[0109] Figure 15 The results are from Comparative Example 4. The film resistance change rates for anhydrous potassium trifluoromethanesulfonate (III) at concentrations of 1, 5, and 10 mM were between -10% and -30%. That is, the reduction rate of film resistance was less than 30% in all cases.

[0110] Thus, it was confirmed that when the cation of trifluoromethanesulfonate is Ce, a lanthanide element, it is more effective as a dopant than when it is K, an alkali metal.

Claims

1. A conductor, comprising: A conductive structure (10) containing conductive carbon material (11) and formed into a predetermined shape, and a dopant (30) that generates an electric charge in the carbon material. The dopant contains trifluoromethanesulfonate, which is composed of trivalent lanthanide ions and trifluoromethanesulfonate anions.

2. The conductor according to claim 1, wherein the lanthanide element is cerium.

3. The conductor according to claim 1, wherein the dopant contains more trivalent cerium ions and trifluoromethanesulfonate anions than trifluoromethanesulfonate anions.

4. The conductor according to claim 1, wherein the lanthanide element is cerium, and the trifluoromethanesulfonate does not contain water molecules.

5. A method for manufacturing a conductive material, comprising: (S1) Prepare a conductive structure containing conductive carbon material and forming it into a specified shape. (S2) Prepare a solution containing a solute and a solvent, using a dopant that generates an electric charge on the carbon material as the solute; (S3) Apply the solution to the conductive structure. (S4) After the solution adheres, the solvent is removed from the conductive structure. In preparing the solution, a solute containing a trifluoromethanesulfonate salt composed of trivalent lanthanide ions and trifluoromethanesulfonate anions is used as the solute.

6. The method for manufacturing a conductor according to claim 5, wherein the lanthanide element is cerium.

7. In the method for manufacturing a conductor according to claim 5, when preparing the solution, a solute containing more trivalent cerium ions and trifluoromethanesulfonate anions than a trifluoromethanesulfonate composed of tetravalent cerium ions and trifluoromethanesulfonate anions is used as the solute.

8. The method for manufacturing a conductor according to claim 5, wherein the lanthanide element is cerium, and the trifluoromethanesulfonate is free of water molecules.

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