Transparent electrode and measuring device

Abstract

Provided is a transparent electrode disposed on an insulating substrate and formed to come into contact with and be electrically connected to a target object. The transparent electrode comprises: a conductive layer that is disposed on the insulating substrate and includes a metal oxide layer having at least one of a metal layer or conductivity; a transparent electrode layer that is disposed on the conductive layer and contains SnO2 as the main component; and a current collector disposed on at least a portion of a side surface of the transparent electrode layer and electrically connected to the transparent electrode layer and the conductive layer.

Description

Transparent electrodes and measuring devices

[0001] The present disclosure relates to a transparent electrode that can be mounted on a measuring device such as a wearable device and a measuring device mounted with the electrode.

[0002] A related art discloses a display unit in which display cells are arranged, including a transparent front substrate having a first transparent electrode on an inner surface within a case having a back cover installed therein, a transparent rear substrate having a second transparent electrode on an inner surface, and a fixing frame for two substrates forming a closed space between the substrates, and a control means causes temporal information to be displayed on the display cells.

[0003] As interest in health has increased recently, the demand for and use of smart wearable devices that can monitor physical health in real time are rapidly expanding.

[0004] There are two common methods for acquiring biometric information from wearable devices: electrical and optical measurements. For optical measurements, the external components of the optical measurement unit must have high transmittance at the wavelength used for measurement. Meanwhile, electrical measurement units are typically composed of metal electrodes, making them optically opaque. Consequently, overlapping electrical and optical measurement units within the limited external space of a wearable device is difficult, particularly when both are installed, limiting design freedom.

[0005] When incorporating the two types of measurement components described above into a wearable device, one option is to use well-known transparent electrodes. Typically, transparent electrodes, like conventional transparent electrodes, are formed from materials that combine high conductivity and light transmittance, such as ITO. However, these types of transparent electrodes are typically placed in enclosed spaces, such as the inside of a case, and durability is not a consideration. Therefore, they cannot be placed on the outermost surface of the device, limiting design freedom.

[0006] To solve the problems of conventional transparent electrodes, the present disclosure provides a novel transparent electrode that maintains transparency, which was not considered in conventional transparent electrodes, while also possessing physical and chemical durability.

[0007] The present disclosure provides a transparent electrode and a measuring device that have physical and chemical durability that can withstand placement on the outermost surface of a device while ensuring transparency, and that can improve the design freedom of a device by using an electrical measuring unit and an optical measuring unit together.

[0008] The above object of the present disclosure is achieved by any one of the following (1) to (7).

[0009] (1) A transparent electrode formed to be electrically connected by being placed on an insulating substrate and in contact with a target object, comprising: a conductive layer disposed on the insulating substrate and including a metal oxide layer having at least one of a metal layer and a conductive property; a transparent electrode layer disposed on the conductive layer and having SnO2 as a main component; and a current collector disposed on at least a portion of a side surface of the transparent electrode layer and electrically connected to the transparent electrode layer and the conductive layer.

[0010] (2) The transparent electrode described in (1), wherein the metal layer of the conductive layer is formed so that, when the film thickness of the metal layer exceeds 5 nm, the projected area on the insulating substrate when looking down at the metal layer is 30% or less of the area of ​​the insulating substrate.

[0011] (3) A transparent electrode in which the metal layer includes one or more elements selected from Ag, Al, Cr, Cu, Au, Pt, Ti, Mo, Nb, and Nd, and the transparent electrode layer includes one or more elements selected from In, Ga, Nb, Ta, W, Zn, Sn, Zr, Si, and F.

[0012] (4) The transparent electrode according to any one of (1) to (3), wherein the metal layer comprises a first metal portion formed of a first metal selected from the group of Au, Pt, Ti, Mo, and Nd, and a second metal portion formed of a second metal selected from the group of Ag, Al, Cr, Cu, and Nb, and the first metal portion is arranged to cover the second metal portion so that the second metal portion is not exposed to the outside.

[0013] (5) The transparent electrode according to any one of (1) to (4), wherein the current collector comprises a first metal selected from the group consisting of Au, Pt, Ti, Mo and Nd, and is formed to cover at least a portion of the side surface of the transparent electrode layer and the outermost surface of the conductive layer.

[0014] (6) A transparent electrode according to any one of (1) to (5), wherein the transparent electrode layer is formed to have a film thickness of 50 nm or more and 200 nm or less.

[0015] (7) A measuring device comprising the transparent electrode described in any one of (1) to (6) above.

[0016] The transparent electrode of the present invention has physical and chemical durability that can withstand placement on the outermost surface of a device while ensuring transparency, and can be used as an electrode of an electrical measurement unit by placing a transparent electrode layer on the outermost surface. Therefore, since the electrode portion, which was previously optically opaque, can be made transparent, it becomes possible to overlap the electrical measurement unit and the optical measurement unit in a wearable device with a relatively small external area. Therefore, a wearable device equipped with the transparent electrode of the present invention reduces design restrictions while increasing the degree of freedom in measurement methods, thereby enabling more optical measurements. Furthermore, by using the transparent electrode of the present invention, optical biometric information can be acquired over a larger area, thereby improving the measurement accuracy of biometric information. Furthermore, when the electrode portion is composed solely of a metal electrode, the exterior is limited to an opaque material with a metallic structure from the standpoint of design. However, by using the transparent electrode of the present invention, it becomes possible to implement a design on the lower layer of the electrode, which can also improve the design of the device.

[0017] According to one aspect of the present disclosure, a transparent electrode may be electrically connected to an object that is on an insulating substrate and in contact with the object. The transparent electrode may include: a conductive layer positioned on the insulating substrate and including at least one of a metal layer and a metal oxide layer; a transparent electrode layer comprising SnO2 as a main component; and a current collector positioned on at least a portion of a side surface of the transparent electrode layer and electrically connected to the transparent electrode layer and the conductive layer.

[0018] The above-described aspects and other aspects, features and advantages of specific embodiments of the present disclosure will become more apparent from the accompanying drawings and the following description provided:

[0019] FIG. 1 is a conceptual diagram of a wearable device, which is a measuring device according to a preferred embodiment of the present disclosure.

[0020] Fig. 2 is a cross-sectional view of a transparent electrode according to the present embodiment.

[0021] Figure 3 is an exploded perspective view of a transparent electrode.

[0022] Fig. 4 is a drawing showing a modified example of a conductive layer of a transparent electrode.

[0023] Figure 5 is a cross-sectional view of a transparent electrode of Variant Example 1.

[0024] Figure 6 is a cross-sectional view of a transparent electrode of Variant Example 2.

[0025] Figure 7 is a cross-sectional view of a transparent electrode of Variant Example 3.

[0026] Figure 8 is a cross-sectional view of a transparent electrode of Variant Example 4.

[0027] Figure 9 is a table showing the evaluation results of Examples 1 to 3 in Evaluation Test 1 of the embodiment.

[0028] Fig. 10 is a table showing the evaluation results of Examples 4 to 6 in Evaluation Test 1 of the embodiment.

[0029] Figure 11 is a table showing the evaluation results of Comparative Examples 1 to 4 in Evaluation Test 1 of the embodiment.

[0030] Figure 12 is a table showing the evaluation results of Example A, Example B, and Comparative Example C in Evaluation Test 2 of the embodiment.

[0031] Hereinafter, embodiments for implementing the present disclosure will be described in detail with reference to the drawings. The embodiments illustrated herein are intended to embody the technical ideas of the present disclosure and are not intended to limit the present disclosure. Furthermore, other possible implementation forms, embodiments, and operational techniques conceivable by those skilled in the art without departing from the scope of the present disclosure are all encompassed by the scope and spirit of the present disclosure, as well as the inventions recited in the claims and their equivalents.

[0032] The terminology used in this disclosure is used solely to describe specific embodiments and is not intended to limit other embodiments. The singular form "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Terms and words used herein, including technical or scientific terms, may have the same meaning as commonly understood by those skilled in the art. Terms commonly defined in dictionaries may be interpreted to have the same or similar meaning in the context of the relevant technical field. Unless otherwise defined, such terms should not be construed in an ideal or overly formal sense. Even if a specific term is defined in this disclosure, such term should not be construed to exclude embodiments of the disclosure depending on the specific situation.

[0033] The term "couple" and its derivatives mean direct or indirect communication between two or more elements, whether or not they are in physical contact with each other. The term "comprise" and its derivatives mean including without limitation. The term "or" is an inclusive term meaning "and / or." The phrase "associated" and its derivatives mean including, interconnecting, containing, connecting, communicating, cooperating, interweaving, juxtaposing, proximate, bound, etc. The term "controller" means any device, system, or part thereof that controls the operation of at least one. The functions associated with a particular controller may be centralized or distributed, either locally or remotely. The phrase "at least one" used with a list of items means that various combinations of one or more of the listed items may be used, and only one item from the list may be required. For example, "at least one of A, B, and C" includes A, B, and C, A and B, A and C, B and C, and any combination of A, B, and C, and all variations thereof. As a further example, the expression "at least one of a, b, or c" can refer to a alone, b alone, c alone, both a and b, both a and c, both b and c, all of a, b, and c, or variations thereof. Similarly, the term "set" means one or more. Thus, a set of items can be a single item, or a collection of two or more items.

[0034] In one or more embodiments of the present disclosure described below, a hardware approach is described as an example. However, since one or more embodiments of the present disclosure include techniques utilizing both hardware and software, various embodiments of the present disclosure do not exclude a software-based approach.

[0035] Additionally, the present disclosure may use expressions such as "more than" or "less than" to determine whether a specific condition is satisfied or fulfilled. However, this is merely an explanation for expressing examples, and descriptions of "more than," "less than," and "below" are not excluded. Conditions described as "more than" may be replaced with "more than," conditions described as "less than" may be replaced with "less than," and conditions described as "more than" may be replaced with "more than." "Less than" may be replaced with "more than and less than."

[0036] In addition, the drawings attached to this specification may be schematically expressed by changing the scale, length-width dimension ratio, shape, etc. from the actual object for convenience in order to facilitate illustration and understanding, but they are merely examples and do not limit the interpretation of this disclosure.

[0037] Additionally, unless otherwise specified, measurements and physical properties are made under room temperature (20°C or higher and 25°C or lower) / relative humidity of 40% RH or higher and 50% RH or lower.

[0038] In addition, in the following description, when ordinal numbers such as “first” and “second” are used for explanation, unless specifically stated otherwise, they are used for convenience and do not specify any order.

[0039] In the following embodiments, a wristwatch-type wearable device is exemplified as a measuring device equipped with a transparent electrode (1) according to the present embodiment. However, the measuring device equipped with the transparent electrode (1) of the present disclosure can be applied to other wearable devices other than wristwatch-type devices or other devices other than wearable devices, as long as it is a device that measures information of a measured object such as biometric information.

[0040] The configuration of a transparent electrode (1) according to one embodiment of the present disclosure will be described with appropriate reference to FIGS. 1 to 8. However, FIGS. 1 to 8 relate to a transparent electrode (1) and a measuring device according to one embodiment of the present disclosure, and the transparent electrode (1) of the present embodiment is not limited to the configuration described by these drawings.

[0041] FIG. 1 conceptually illustrates a part of a wearable device (100) that includes a transparent electrode (1) according to the present embodiment and is a measuring device that measures predetermined information such as biometric information.

[0042] Wearable Device

[0043] A wearable device (100) is a device that is worn on a specific part of the wearer's body, such as the arm. The wearable device (100) has a function that can measure information for purposes such as biometric information. For example, in the case of a wristwatch, it can function as a wristwatch and also as a measuring device.

[0044] As illustrated in FIG. 1, the wearable device (100) includes an optical measuring unit (120) that optically measures bio-information such as heart rate and blood flow by having a light emitting unit that irradiates light and a light receiving unit that detects the intensity of infrared light reflected from the body within the device body (110), an electrical measuring unit (130) that measures bio-potential and electrically measures bio-information such as body composition (body fat percentage, muscle mass, etc.), a display unit (140) that is arranged on the upper surface of the device body (110) and displays various types of information, a control unit (150) that comprehensively performs driving control of each unit, and a power unit (160) that supplies driving power to each unit. In addition, the configuration of the wearable device (100) is not limited to the configuration described above, and may include a function realization unit that realizes other functions required as a device configuration.

[0045] Embodiments of the present disclosure may be described and illustrated in terms of blocks that perform the described function or functions as illustrated in the drawings. These blocks, which may be referred to herein as (optical measurement unit (120), electrical measurement unit (130), display unit (140), power supply unit (160), etc.), may be physically implemented by one or more analog circuits and / or digital circuits including logic gates, integrated circuits, microprocessors, microcontrollers, memory circuits, passive electronic components, active electronic components, optical components, etc., and may also be implemented or driven by software or firmware (configured to perform the functions or operations described herein). The circuits may be implemented on, for example, one or more semiconductor chips or on a substrate support such as a printed circuit board. The circuitry included in a block may be implemented by dedicated hardware, processors (e.g., one or more programmed microprocessors and associated circuits), or a combination of dedicated hardware that performs some functions of the block and processors that perform other functions. Each block of the embodiments may be physically separated into two or more interacting individual blocks. Likewise, blocks of the embodiment can be physically combined into more complex blocks.

[0046] Transparent electrode

[0047] As illustrated in Fig. 1, a transparent electrode (1) is installed at a predetermined location (e.g., the lower surface of the device, which serves as the mounting surface) of a wearable device (100). The transparent electrode (1) may be placed at a location that can come into contact with the wearer's skin.

[0048] The transparent electrode (1) includes an insulating substrate (10), a transparent electrode layer (20), a conductive layer (30), and a current collector (40), as illustrated in FIG. 2. As illustrated in FIG. 2 and FIG. 3, the transparent electrode (1) includes a conductive layer (30) disposed on the insulating substrate (10), a transparent electrode layer (20) disposed on the conductive layer (30), and a current collector (40) disposed so as to cover at least a portion of a side surface (21) of the transparent electrode layer (20).

[0049] Insulating substrate

[0050] The insulating substrate (10) is made of an insulating material such as alkali-free glass. The insulating substrate (10) blocks electrical connection between the transparent electrode (1) and the internal devices of the wearable device (100).

[0051] <Transparent electrode layer>

[0052] The transparent electrode layer (20) is composed of a conductive metal oxide and is placed on the conductive layer (30). The transparent electrode layer (20) is electrically connected to the conductive layer (30). As shown in Fig. 1, the transparent electrode layer (20) is located on the outermost surface of the lower surface of the wearable device (100). Therefore, the transparent electrode (1) can be in contact with and electrically connected to a target object (such as the wearer's skin).

[0053] The transparent electrode layer (20) is composed of a material that has conductivity and transparency, as well as physical and chemical durability. To achieve these properties, the transparent electrode layer (20) may be composed of a metal oxide mainly composed of SnO2. Compared to metal oxides mainly composed of In2O3, such as ITO, SnO2 is chemically stable and also has excellent durability.

[0054] The transparent electrode layer (20) is mainly composed of SnO2, and it is preferable to add at least one element selected from In, Ga, Nb, Ta, W, Zn, Sn, Zr, Si, and F, and it is particularly preferable to add F.

[0055] If the transparent electrode layer (20) is formed only of SnO2, durability is obtained, but the surface resistance increases, and if the film thickness is increased for the purpose of lowering the surface resistance, transparency is damaged, which is not desirable. In contrast, the transparent electrode layer (20) according to the present embodiment can lower the surface roughness (Ra) while controlling the average particle diameter in the film to be small when the film is formed by a sputtering method by adding one or more of the above-described elements to the main component, SnO2. In addition, the transparent electrode layer (20) has improved surface smoothness by lowering the surface roughness (Ra). Therefore, the transparent electrode layer (20) is less likely to wear out when friction occurs between it and the wearer's skin, and can exhibit excellent durability.

[0056] From the viewpoint of durability and transparency, the transparent electrode layer (20) preferably has a film thickness of 50 nm or more and 200 nm or less, and more preferably 60 nm or more and less than 200 nm. By controlling the film thickness of the transparent electrode layer (20) within the above-described range, durability, conductivity, and transparency as a transparent electrode can be secured. Here, if the film thickness of the transparent electrode layer (20) is less than 50 nm, durability and conductivity may be lowered, which may deteriorate the function as a transparent electrode (1), and thus, this is not preferable. In addition, if the film thickness of the transparent electrode layer (20) exceeds 200 nm, transparency may be lowered, which may prevent the optical measurement unit (120) from sufficiently demonstrating its measurement performance, and thus, this is not preferable.

[0057] From the viewpoint of durability, the transparent electrode layer (20) preferably has a surface roughness (Ra) of 3.3 nm or less, a maximum height roughness (Rz) of 33 nm or less, and a film density of 6.8 g / cm-3 or more. The surface roughness (Ra) and the maximum height roughness (Rz) can be measured in accordance with JIS B0601-2001. The film density can be measured, for example, by the X-ray reflectivity method (XRR). By setting the surface roughness (Ra), the maximum height roughness (Rz), and the film density of the transparent electrode layer (20) to the above-described values, wear due to friction of the wearer's skin, etc. can be suppressed, thereby maintaining high durability.

[0058] In terms of transmittance, it is preferable that the transparent electrode layer (20) have an average transmittance of 80% or more for light having a wavelength range of 500 nm or more and 950 nm or less. The average transmittance can be measured in accordance with JIS R3106-2019. By making the transparent electrode layer (20) have an average transmittance of 80% or more, the optical measurement unit (120) can accurately obtain the necessary optical information. If the average transmittance of the transparent electrode layer (20) is less than 80%, the optical information transmitted through the transparent electrode layer (20) decreases, making it difficult for the optical measurement unit (120) to obtain accurate information, which is not preferable.

[0059] From the viewpoint of conductivity, it is preferable that the transparent electrode layer (20) have a resistance of 200Ω·cm or less between the central portion and the outer peripheral portion when viewed in a plane, and that the surface resistance of the central portion be 220Ω / sq or less. Accordingly, although the surface resistance and resistance of the transparent electrode layer (20) are higher than those of a general metal electrode, it has sufficient electrode performance for measuring bio-information, and thus can be used as a replacement for a conventional metal electrode. In addition, in order to obtain accurate electrical bio-information, it is preferable that the resistance of the transparent electrode itself be low.

[0060] <Challenge Layer>

[0061] As shown in Fig. 2, the conductive layer (30) is electrically connected to the transparent electrode layer (20) and the current collector (40), and is interposed between the insulating substrate (10) and the transparent electrode layer (20). The conductive layer (30) is connected to the electrical measurement unit (130), etc. The conductive layer (30) is formed of a metal layer (31) and / or a conductive metal oxide layer (32).

[0062] When the conductive layer (30) is formed of only the metal layer (31) or a laminated structure of the metal layer (31) and the metal oxide layer (32), from the viewpoint of transparency, when the film thickness exceeds 5 nm, it is preferable that the projected area on the insulating substrate (10) when viewed in a plan view be 30% or less of the area of ​​the insulating substrate (10). As a structure of the conductive layer (30) having such a projected area, as shown in Fig. 4, a shape in which an opening (33) communicating with the insulating substrate (10) is formed, such as (a) a lattice shape, (b) a line shape, (c) a ring shape, (d) a concave shape in which a portion of the film is cut out, or (e) a spiral shape, is preferably exemplified.

[0063] In addition, the shape of the conductive layer (30), the formation position, the opening shape or opening size of the opening (33), etc. are not limited to the shape shown in Fig. 4, and can be appropriately designed according to the device configuration (configuration, arrangement position, etc. of the mounted optical measuring unit (120), as long as the projected area on the insulating substrate (10) is at least 30% or less of the area of ​​the insulating substrate (10).

[0064] The metal constituting the metal layer (31) can be composed of one or more elements selected from Ag, Al, Cr, Cu, Au, Pt, Ti, Mo, Nb, and Nd. Among these metals, a metal selected from the Au, Pt, Ti, Mo, and Nd group can be classified as a “first metal,” and a metal selected from the Ag, Al, Cr, Cu, and Nb group can be classified as a “second metal.” Here, the “first metal” is a highly durable metal that has the properties of being easy to process and having good durability, but having slightly poor conductivity. The “second metal” is a highly conductive metal that has the properties of being easy to process and having good conductivity, but having poor durability (particularly, acid / alkali resistance). The conductive layer (30) can be composed of a first metal portion (31A) as the part formed from the first metal, and a second metal portion (31B) as the part formed from the second metal.

[0065] When the conductive layer (30) is composed of only a metal layer (31), the two types of metals (first metal, second metal) suitable as the conductive layer (30) are appropriately combined, and the first metal portion (31A) is arranged to surround the second metal portion (31B), thereby complementing the disadvantages of both (low durability, low conductivity) and utilizing the advantages of both (high durability, high conductivity) (see Fig. 8).

[0066] In addition to the form shown in Fig. 2, the conductive layer (30) may have a form as shown in Figs. 5 to 8 as a modified example.

[0067] The conductive layer (30) can have a laminated structure in which a conductive layer (30) made of a second metal portion (31B) is formed on an insulating substrate (10), as illustrated in FIG. 5, and a transparent electrode layer (20) is formed on the conductive layer (30). In the form illustrated in FIG. 5, since the conductive layer (30) is formed of a second metal portion (31B) that is insufficient in durability, the exposed portion of the outermost surface of the conductive layer (30) is covered with a current collector (40) made of a first metal that is superior in durability, and thus is not exposed to the outside. In addition, since the form illustrated in FIG. 5 does not form an opening (33) in the conductive layer (30) made of only metal, from the viewpoint of transparency, it is preferable that the film thickness of the conductive layer (30) be 5 nm or less.

[0068] The conductive layer (30) can have a laminated structure in which, as illustrated in FIG. 6, a conductive layer (30) made of a metal oxide layer (32) formed of a metal oxide is formed on an insulating substrate (10), and a transparent electrode layer (20) is formed on the conductive layer (30). In the form illustrated in FIG. 6, the conductive layer (30) is formed of a metal oxide with low durability, but the exposed portion located on the outermost surface of the conductive layer (30) is covered with a current collector (40) made of a first metal with excellent durability, so that it is not exposed to the outside. Therefore, the conductive layer (30) made of the metal oxide layer (32) can also use a transparent conductive material with low durability, such as ITO.

[0069] As shown in Fig. 7, the conductive layer (30) can be formed as a two-layer conductive layer (30) on an insulating substrate (10) with a second metal portion (31B) having an opening (33) formed as a lower layer and a metal oxide layer (32) formed as an upper layer, and a laminated structure in which a transparent electrode layer (20) is formed on the conductive layer (30). In addition, the current collector (40) is made of the first metal and is formed to cover the outer peripheral surface of the conductive layer (30). In the form shown in Fig. 7, the lower surface of the conductive layer (30) is entirely covered with the insulating substrate (10), and the exposed portion of the outermost surface is covered with the current collector (40) having excellent durability, so that it is not exposed to the outside. Therefore, the conductive layer (30) can also be formed with a metal oxide layer (32) made of a transparent conductive material with low durability, such as ITO.

[0070] As illustrated in Fig. 8, the conductive layer (30) can be formed as a two-layer conductive layer (30) on an insulating substrate (10) with a second metal portion (31B) as a lower layer and a first metal portion (31A) as an upper layer, and can have a laminated structure in which a transparent electrode layer (20) is formed on the conductive layer (30). The conductive layer (30) is arranged so that the first metal portion (31A) composed of the first metal surrounds the second metal portion (31B) composed of the second metal. As a result, as illustrated in Fig. 8, when forming the electrode, the transparent electrode layer (20) enters the opening (33), so that the portion of the second metal portion (31B) is not exposed to the outside. Therefore, in the form shown in Fig. 8, the exposure of the second metal portion (31B) is prevented, and the durability, which is a defect of the second metal, can be supplemented while the conductivity of the second metal portion (31B) can be utilized. In addition, in the form shown in Fig. 8, the conductive layer (30) is made of metal and is arranged to cover a part of the side surface (21) of the transparent electrode layer (20), so that it can fulfill the function of the current collector (40). Therefore, there is no need to form the current collector (40) separately, so that the configuration can be simplified.

[0071] The film thickness of the conductive layer (30) is preferably 5 nm or more and 100 nm or less from the viewpoint of transparency and conductivity, and a thinner film is preferable when considering transparency. In addition, the film thickness of the conductive layer (30) can be appropriately set by combining the metal layer (31) and / or the metal oxide layer (32) while taking transparency, etc. into consideration.

[0072] <Collection Department>

[0073] The current collector (40) is arranged to cover at least a portion of the side surface (21) of the transparent electrode layer (20). As illustrated in FIG. 2, the current collector (40) is arranged at the edge of the conductive layer (30), and can be arranged to cover a portion of the side surface (21) of the transparent electrode layer (20) over the entire circumference. The current collector (40) reduces the connection resistance between the transparent electrode layer (20) and the internal circuit (wristwatch, wearable device, etc.).

[0074] The constituent material of the current collector (40) is a metal material capable of electrical connection with the transparent electrode layer (20) and the conductive layer (30). Specifically, the constituent material of the current collector (40) can preferably be a first metal (a metal selected from the group consisting of Au, Pt, Ti, Mo, and Nd) used in the current collector (40). The current collector (40) can obtain high durability by being formed of the first metal. Therefore, if the current collector (40) is formed to cover at least a portion of the side surface of the transparent electrode layer (20) and the outermost surface of the conductive layer (30), the durability of the transparent electrode (1) can be increased.

[0075] The method for forming the transparent electrode layer (20), conductive layer (30), and current collector (40) constituting the transparent electrode (1) may include vacuum deposition, physical vapor deposition (PVD), chemical vapor deposition (CVD), and spray pyrolysis (SPD), and an optimal method may be selected depending on the forming material. In particular, the PVD method capable of forming a dense thin film is preferable.

[0076] As described above, the transparent electrode (1) according to the present embodiment is an electrode formed on an insulating substrate (10) and electrically connected by contacting with a target object, and the transparent electrode (1) has a laminated structure in which a transparent electrode layer (20) mainly composed of SnO2 and a conductive layer (30) formed of a metal layer (31) and / or a conductive metal oxide layer (32) are laminated in this order from the outermost surface side, and at least a part of a side surface (21) of the transparent electrode layer (20) is covered with a current collector (40) that is electrically connected to the transparent electrode layer (20) and the conductive layer (30).

[0077] In addition, in the transparent electrode (1) according to the present embodiment, when the film thickness of the metal layer (31) of the conductive layer (30) exceeds 5 nm, it is preferable to form it so that the projected area on the insulating substrate (10) when viewed in a plane is 30% or less of the area of ​​the insulating substrate (10).

[0078] In addition, in the transparent electrode (1) according to the present embodiment, it is preferable that the metal layer (31) be formed by containing one or more elements selected from Ag, Al, Cr, Cu, Au, Pt, Ti, Mo, Nb, and Nd, and the transparent electrode layer (20) be formed by containing one or more elements selected from In, Ga, Nb, Ta, W, Zn, Sn, Zr, Si, and F.

[0079] In addition, in the transparent electrode (1) according to the present embodiment, the metal layer (31) has a first metal portion (31A) formed of a first metal selected from the group of Au, Pt, Ti, Mo, and Nd, and a second metal portion (31B) formed of a second metal selected from the group of Ag, Al, Cr, Cu, and Nb, and it is preferable that the first metal portion (31A) be arranged so as to prevent exposure of the second metal portion (31B).

[0080] In addition, in the transparent electrode (1) according to the present embodiment, the current collector (40) is preferably formed of a first metal selected from the group consisting of Au, Pt, Ti, Mo, and Nd, and is formed to cover at least a portion of the side surface (21) of the transparent electrode layer (20) and the outermost surface of the conductive layer (30).

[0081] In addition, in the transparent electrode (1) according to the present embodiment, it is preferable that the transparent electrode layer (20) has a film thickness of 50 nm or more and 200 nm or less.

[0082] In addition, the above-described transparent electrode (1) can be provided in a measuring device such as a wearable device (100) having a measuring function including an optical measuring unit (120) and an electrical measuring unit (130).

[0083] By this configuration, since a transparent electrode layer (20) having both physical and chemical durability and transparency can be arranged on the outermost surface, by using it as an electrode of an electrical measurement unit (130), the electrode portion made of metal, which was optically opaque in the past, can be made transparent. Therefore, in a wearable device (100) with a relatively small external area, it becomes possible to arrange the electrical measurement unit (130) and the optical measurement unit (120) to overlap each other. Therefore, a wearable device (100) equipped with a transparent electrode (1) reduces design restrictions while increasing the degree of freedom in the measurement method, thereby enabling more optical measurements. In addition, by using the transparent electrode (1) of the present disclosure in a wearable device (100) or the like, optical biometric information acquisition becomes possible over a larger area, thereby improving the measurement precision of biometric information. In addition, in the case where the electrode portion is composed of only a metal electrode, as in the conventional product, the exterior is limited to an opaque material of a metal structure from the viewpoint of design, but by using the transparent electrode (1) of the present disclosure, it becomes possible to implement a design on the lower layer of the electrode, thereby improving the design of the device. The effects of the present disclosure will be described using the following examples and comparative examples. However, the technical scope of the present disclosure is not limited to the following examples.

[0084] [Evaluation Test 1]

[0085] A performance test was conducted on each sample of the examples and comparative examples shown below.

[0086] <Sample production>

[0087] Samples of the examples (Examples 1 to 6) and samples of the comparative examples (Comparative Examples 1 to 4) were manufactured according to the following process.

[0088] <Manufacture of sample of Example 1>

[0089] The sample of Example 1 was formed by laminating a conductive layer on an insulating substrate formed of alkali-free glass with a diameter of 26 mm, and laminating a transparent electrode layer thereon (shape of Fig. 8). The conductive layer and the transparent electrode layer were formed by a sputtering method. A DC magnetron sputtering device (manufactured by Showa Shinku Co., Ltd.) was used to form the conductive layer, and a sputtering device (manufactured by Toshima Seisakusho Co., Ltd.) was used to form the transparent electrode layer. The film formation conditions for the conductive layer were as follows: Ar gas was introduced under a vacuum degree of 10-3 Pa or less within the device; the pressure was 0.4 Pa; and the discharge power was DC30 W. The film formation conditions for the transparent electrode layer were as follows: Ar gas was introduced under a vacuum degree of 10-3 Pa or less within the device; the pressure was 0.4 Pa; and the discharge power was RF100 W. In addition, the substrate during film formation was heated to 100°C to form the film. The conductive layer was formed by laminating a first metal (Mo) having a thickness of 20 nm on a second metal (Al) having a thickness of 30 nm. The conductive layer had a grid shape by arranging multiple 2 mm × 2 mm square openings in a matrix shape. The transparent electrode layer was formed by forming a thin film mainly composed of SnO2. Five types of samples of Example 1 were produced on the conductive layer, with film thicknesses of 30 nm, 60 nm, 100 nm, 200 nm, and 300 nm. The current collector was used in combination with the conductive layer. The sample of Example 1 had the shape shown in Fig. 8.

[0090] <Manufacture of sample of Example 2>

[0091] The sample of Example 2 was formed by laminating a conductive layer on an insulating substrate formed of alkali-free glass with a diameter of 26 mm, and laminating a transparent electrode layer thereon. The conductive layer and the transparent electrode layer were formed in the same manner as in Example 1. The conductive layer was formed with a second metal (Al) having a film thickness of 3 nm without forming an opening. The transparent electrode layer was formed with SnO2. The sample of Example 2 was formed in five types with film thicknesses of 30 nm, 60 nm, 100 nm, 200 nm, and 300 nm on the conductive layer. The current collector was formed by covering the conductive layer using the first metal (Mo) so that it was not exposed. The sample of Example 2 had the shape illustrated in Fig. 5.

[0092] <Manufacture of sample of Example 3>

[0093] The sample of Example 3 was formed by laminating a conductive layer on an insulating substrate formed of alkali-free glass with a diameter of 26 mm, and laminating a transparent electrode layer thereon. The conductive layer and the transparent electrode layer were formed in the same manner as in Example 1. The conductive layer was formed of a second metal (Al) with a film thickness of 30 nm. The conductive layer had a grid shape by arranging multiple 2 mm × 2 mm openings in a matrix shape. The transparent electrode layer was formed of SnO2. The sample of Example 3 was formed in five types with film thicknesses of 30 nm, 60 nm, 100 nm, 200 nm, and 300 nm on the conductive layer. The current collector was formed by covering the conductive layer using the first metal (Mo) so that it was not exposed. The sample of Example 3 had the shape shown in Fig. 2.

[0094] <Manufacture of sample of Example 4>

[0095] The sample of Example 4 was formed by laminating a conductive layer on an insulating substrate formed of alkali-free glass with a diameter of 26 mm, and laminating a transparent electrode layer thereon. The conductive layer and the transparent electrode layer were formed by a sputtering method, similar to Example 1. The conductive layer was formed with a metal oxide (ITO) having a film thickness of 100 nm without forming an opening. The transparent electrode layer was formed with SnO2. The sample of Example 4 was formed in five types with film thicknesses of 30 nm, 60 nm, 100 nm, 200 nm, and 300 nm on the conductive layer. The current collector was formed by covering the conductive layer using the first metal (Mo) so that it was not exposed. The sample of Example 4 had the shape illustrated in Fig. 6.

[0096] <Manufacture of sample of Example 5>

[0097] The sample of Example 5 was formed by laminating a conductive layer on an insulating substrate formed of alkali-free glass with a diameter of 26 mm, and laminating a transparent electrode layer thereon. The conductive layer and the transparent electrode layer were formed by a sputtering method, similar to Example 1. The conductive layer was formed by laminating a metal oxide (ITO) with a film thickness of 100 nm on a second metal (Al) with a film thickness of 30 nm. The layer formed of the second metal had a lattice shape by arranging multiple 2 mm × 2 mm openings in a matrix shape. The transparent electrode layer was formed of SnO2. The sample of Example 5 was formed in five types with film thicknesses of 30 nm, 60 nm, 100 nm, 200 nm, and 300 nm on the conductive layer. The current collector was formed by covering the first metal (Mo) so that the conductive layer was not exposed. The sample of Example 5 has the shape shown in Fig. 7.

[0098] <Manufacture of sample of Example 6>

[0099] The sample of Example 6 was formed by laminating a conductive layer on an insulating substrate formed of alkali-free glass with a diameter of 26 mm, and laminating a transparent electrode layer thereon. The conductive layer and the transparent electrode layer were formed by a sputtering method, similar to Example 1. The conductive layer was formed by laminating a first metal (Mo) with a film thickness of 20 nm on a second metal (Al) with a film thickness of 30 nm. The conductive layer had a lattice shape by arranging multiple 2 mm × 2 mm openings in a matrix shape. The transparent electrode layer was formed with SnO2 as the main component and F added (SnO2: 95 parts by mass, F: 5 parts by mass). The sample of Example 6 was formed in five types, with film thicknesses of 30 nm, 60 nm, 100 nm, 200 nm, and 300 nm, on the conductive layer. The current collector was used in combination with the conductive layer. The sample of Example 6 had a shape shown in Fig. 8, similar to Example 1.

[0100] <Manufacture of sample of comparative example 1>

[0101] The sample of Comparative Example 1 was formed by laminating a conductive layer on an insulating substrate formed of alkali-free glass with a diameter of 26 mm, and laminating a transparent electrode layer thereon. The conductive layer and the transparent electrode layer were formed by a sputtering method similar to Example 1. The conductive layer was formed of a second metal (Al) with a film thickness of 30 nm. The layer formed of the second metal had a lattice shape by arranging multiple 2 mm × 2 mm openings in a matrix shape. The transparent electrode layer was formed of SnO2. The sample of Example 5 was formed by forming five types of films with film thicknesses of 30 nm, 60 nm, 100 nm, 200 nm, and 300 nm on the conductive layer. The current collector was used in combination with the conductive layer. The sample of Comparative Example 1 has a shape in which the first metal layer among the conductive layers of Example 1 is not formed.

[0102] <Manufacture of sample of comparative example 2>

[0103] The sample of Comparative Example 2 was formed by laminating a conductive layer on an insulating substrate formed of alkali-free glass with a diameter of 26 mm, and laminating a transparent electrode layer thereon. The conductive layer and the transparent electrode layer were formed by a sputtering method similar to Example 1. The conductive layer was formed with a metal oxide (ITO) having a film thickness of 100 nm. The transparent electrode layer was formed with SnO2. The sample of Comparative Example 2 was formed in five types with film thicknesses of 30 nm, 60 nm, 100 nm, 200 nm, and 300 nm on the conductive layer. The current collector was used in combination with the conductive layer. The sample of Comparative Example 2 has a shape that does not form the current collector of Example 4.

[0104] <Manufacture of sample of comparative example 3>

[0105] The sample of Comparative Example 3 was formed by laminating only a transparent electrode layer made of SnO2 on an insulating substrate formed of alkali-free glass with a diameter of 26 mm without forming a conductive layer. The transparent electrode layer was formed by a sputtering method, similar to Example 1. The sample of Comparative Example 3 was produced in five types with film thicknesses of 30 nm, 60 nm, 100 nm, 200 nm, and 300 nm on an insulating substrate. The sample of Comparative Example 3 has a shape in which the conductive layer of Comparative Example 2 is not formed.

[0106] <Manufacture of sample of comparative example 4>

[0107] The sample of Comparative Example 4 was formed by laminating only a conductive layer formed of a metal oxide (ITO) with a film thickness of 100 nm on an insulating substrate formed of alkali-free glass with a diameter of 26 mm, without forming a transparent electrode layer. The conductive layer was formed by a sputtering method, similar to Example 1. The sample of Comparative Example 4 is formed in a shape in which the transparent electrode layer of Comparative Example 2 is not formed.

[0108] <Test Contents>

[0109] For each sample of the examples and comparative examples manufactured in the above-described order, a physical durability test, a chemical durability test, a conductivity test, and a transparency test were performed.

[0110] Physical durability test

[0111] In the physical durability test, a φ6 mm eraser was placed on the surface of the transparent electrode layer of each sample under a load of 1 kg, and a reciprocating friction tester (product name: TYPE30S, manufactured by Shinto Chemical Co., Ltd.) was used to move the sample back and forth 3,000 times at a moving distance of 15 mm and a moving speed of 40 reciprocations / min. After the test, the electrode exterior was checked for damage with the naked eye and under a microscope. The evaluation criteria are as follows.

[0112] ○: No wounds observed with the naked eye or under a microscope

[0113] △: No wounds observed with the naked eye, but wounds observed under a microscope

[0114] ×: There are wounds observed with the naked eye and under a microscope.

[0115] <Chemical durability test>

[0116] The chemical durability test was conducted by placing transparent electrodes so that there were immersed and unimmersed portions in a solution adjusted to pH 4.6 (buffer solution pH 4.6 (C8H5KO4-NaOH), manufactured by Tokyo Kasei Kogyo Co., Ltd.) and leaving them for 48 hours, and observing changes in appearance before and after the test. The evaluation criteria are as follows.

[0117] ○: There is a change

[0118] ×: No change.

[0119] Challenge Test

[0120] The conductivity test was performed using a surface resistance meter (product name: Loresta-GX MCP-T700, manufactured by Nitto Seiko Analytech Co., Ltd.) to measure the surface resistance (Ω / sq) at four terminals in the center of the sample. In addition, the resistance (Ω) between the center of the sample and the current collector (approximately 15 mm) was measured using a resistance meter (product name: RM3548, manufactured by Nitto Seiko Analytech Co., Ltd.). The evaluation criteria are as follows.

[0121] · Surface resistance

[0122] ○: Less than 200Ω / sq

[0123] ×: 200Ω / sq or more

[0124] · Resistance between the central and collector units

[0125] ○: Less than 220Ω

[0126] ×: 220Ω or more.

[0127] Transparency Test

[0128] Transparency testing was conducted using an ultraviolet-visible spectrophotometer (Product name: UV-1900, manufactured by Shimadzu Seisakusho Co., Ltd.), and the average values ​​for the transmittance of each sample at wavelengths of 530 nm, 660 nm, and 940 nm were calculated. The evaluation criteria are as follows.

[0129] ○: Average transmittance of 80% or more

[0130] △: Average transmittance of 70% or more but less than 80%

[0131] ×: Average transmittance less than 70%.

[0132] <Result>

[0133] Figure 9 shows the results of Specification and Evaluation Test 1 for each sample of Examples 1 to 3. Figure 10 shows the results of Specification and Evaluation Test 1 for each sample of Examples 4 to 6. Figure 11 shows the results of Specification and Evaluation Test 1 for each sample of Comparative Examples 1 to 4.

[0134] As shown in each table of FIG. 9 or FIG. 10, the sample of the transparent electrode layer of Example 1 having a film thickness of 100 nm, the sample of the transparent electrode layer of Example 2 having a film thickness of 60 nm and 100 nm, the sample of the transparent electrode layer of Example 3 having a film thickness of 100 nm, and the sample of the transparent electrode layer of Examples 4 and 5 having a film thickness of 30 nm, 60 nm, and 100 nm all had evaluations of physical durability, chemical durability, conductivity, and transparency as “○,” indicating that sufficient quality could be guaranteed as a product. In addition, from the results of Examples 1 to 6, it was found that "by covering the second metal of the conductive layer with the first metal, chemical durability of the exposed portion of the conductive layer (current collector) is obtained", "transparency can be secured by setting the film thickness of the transparent electrode layer to 50 nm or more and 200 nm or less", "transparency can be secured without being affected by the film thickness of the conductive layer by forming an opening in the conductive layer", "chemical durability can be obtained by forming the current collector with a highly durable first metal and covering it with a conductive layer", and "by adding a predetermined additive to the transparent electrode layer containing SnO2 as a main component, crystal grains in the film do not grow significantly, and physical durability does not decrease even if the film is thickened".

[0135] Meanwhile, as shown in the table in Fig. 11, Comparative Examples 1 to 4 all showed poor chemical durability or conductivity results, and thus could not satisfy product quality. In addition, from the results of Comparative Examples 1 to 4, it was found that “when the transparent electrode layer is made thin, the transparency tends to be good, but the physical durability and conductivity deteriorate,” “when the transparent electrode layer is made thick, the conductivity tends to be good, but the transparency deteriorates,” “when a conductive layer formed of a second metal is used as a current collector, the second metal with low durability is exposed, so chemical durability is not obtained,” “when the film thickness of the transparent electrode layer is 60 nm or less due to the step difference in the opening of the conductive layer, the covering of the conductive layer is insufficient, so physical durability cannot be obtained,” “when the film thickness of the transparent electrode layer is 200 nm or more, the transparency deteriorates,” “when a conductive layer (metal oxide) is used as a current collector, chemical durability is not obtained because the metal oxide is exposed,” “when durability is obtained with only a transparent electrode layer, it is difficult to secure conductivity,” “when only a conductive layer is used, it is difficult to secure chemical durability.”

[0136] [Evaluation Test 2]

[0137] A performance test was conducted on each sample of the examples and comparative examples shown below.

[0138] <Sample production>

[0139] The transparent electrode layers of Examples A and B were both formed by sputtering.

[0140] The transparent electrode layer of Comparative Example C was formed by the coating pyrolysis method.

[0141] The surface roughness (Ra) and maximum height roughness (Rz) of each sample were analyzed using a scanning probe microscope (SPM) (Product name: SPM-9700HT, Shimadzu Seisakusho Co., Ltd.). The average particle diameter was measured using a SEM device (Product name: Dual Beam FIB Helios 5 UC, Thermo Scientific). The film density was measured by the X-ray reflectance method (XRR) using a fully automatic horizontal sample multipurpose X-ray diffraction device (Product name: SmartLab, Rigaku Co., Ltd.).

[0142] <Test Contents>

[0143] Evaluation Test 2, similar to the physical durability test of Evaluation Test 1, involved placing a φ6 mm eraser with a load of 1 kg on the surface of the transparent electrode layer of each sample and moving it back and forth 3,000 times at a moving distance of 15 mm and a moving speed of 40 round trips / min. After the test, the electrode exterior was visually and microscopically checked for any damage. The evaluation criteria are as follows.

[0144] ○: No wounds observed with the naked eye or under a microscope

[0145] ×: There are wounds observed with the naked eye and under a microscope.

[0146] <Result>

[0147] Figure 12 shows the results of Evaluation Test 2. It was found that both Examples A and B achieved good durability. In contrast, Comparative Example C showed poor durability results and could not satisfy the product quality. From this, it was found that by manufacturing the transparent electrode layer of the transparent electrode with a surface roughness (Ra) of 3.3 nm or less, a maximum height roughness (Rz) of 33 nm or less, and a film density of 6.8 g / cm-3 or more from the viewpoint of durability, a transparent electrode with excellent durability could be obtained.

Claims

1. In a transparent electrode (1) that is placed on an insulating substrate (10) and formed to be electrically connected by contacting a target object, A conductive layer (30) disposed on the insulating substrate, the conductive layer including a metal layer or a metal oxide layer having at least one of conductivity; A transparent electrode layer disposed on the above-mentioned conductive layer and containing SnO2 as a main component; and A transparent electrode including a current collector (40) arranged on at least a portion of a side surface of the transparent electrode layer, the current collector electrically connected to the transparent electrode layer and the conductive layer.

2. In paragraph 1, A transparent electrode formed so that when the metal layer of the conductive layer has a metal layer and the film thickness of the metal layer of the conductive layer exceeds 5 nm, the projected area on the insulating substrate when looking down at the metal layer is 30% or less of the area of ​​the insulating substrate.

3. In paragraph 1, The metal layer comprises at least one of Ag, Al, Cr, Cu, Au, Pt, Ti, Mo, Nb or Nd, The transparent electrode layer is a transparent electrode including at least one of In, Ga, Nb, Ta, W, Zn, Sn, Zr, Si, or and F.

4. In paragraph 1, The metal layer comprises a first metal portion formed of a first metal selected from the group consisting of Au, Pt, Ti, Mo and Nd, and a second metal portion formed of a second metal selected from the group consisting of Ag, Al, Cr, Cu and Nb. A transparent electrode in which the first metal portion is formed to cover the second metal portion so that the second metal portion is not exposed to the outside of the transparent electrode.

5. In paragraph 1, A transparent electrode, wherein the above current collector comprises a first metal selected from Au, Pt, Ti, Mo and Nd, and the first metal is formed to cover at least a portion of a side surface of the transparent electrode layer and the outermost surface of the conductive layer.

6. In paragraph 1, The above transparent electrode layer is a transparent electrode formed to have a film thickness of 50 nm or more and 200 nm or less.

7. In measuring instruments, It includes an insulating substrate (10) and a transparent electrode (1) that is placed on the insulating substrate and can be electrically connected to an object that comes into contact with the object. The above transparent electrode is a conductive layer (30) disposed on the insulating substrate, the conductive layer including a metal layer or a metal oxide layer having at least one of conductivity; A transparent electrode layer (20) containing SnO2 as a main component; and A measuring device comprising a current collector (40) positioned on at least a portion of a side surface of the transparent electrode layer and electrically connected to the transparent electrode layer and the conductive layer.

8. In paragraph 7, The above measuring device is a measuring instrument which is a wearable device.

Images