Electronic apparatus

Abstract

To provide a small electronic apparatus that operates using power from a secondary battery while charging the secondary battery using a solar cell.SOLUTION: An electronic apparatus includes a solar cell and a secondary battery. The solar cell includes a transparent electrode, an electron transport layer formed on the electrode, a light absorbing layer formed on the electron transport layer and containing an electron collector and a dye, a counter electrode disposed opposite the electrode, and a substrate on which the counter electrode is provided. The secondary battery is disposed on a circuit board with the solar cell stacked.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to an electronic device.

Background Art

[0002] The use of sensors as electronic devices has been expanding in many aspects of daily life. For example, vibration sensors are used in environmental management applications in warehouses and factories. Also, human sensors are used for security purposes. Furthermore, recently, gas sensors for detecting gases in the environment, including CO 2 are also being used. In recent years, self-powered sensors that are equipped with secondary batteries such as lithium-ion batteries and perform sensing using the power of these secondary batteries while also charging the secondary batteries are also being increasingly used. As a means for charging the secondary battery in the self-powered sensor without external power supply, a solar cell may be used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, an electronic device that operates using the power of a secondary battery while charging the secondary battery with a solar cell is to be equipped with the secondary battery and the solar cell. Even when the secondary battery and the solar cell are mounted, a small-sized electronic device is required.

[0005] An object of the present disclosure is to provide a small-sized electronic device that operates using the power of a secondary battery while charging the secondary battery with a solar cell.

Means for Solving the Problems

[0006] An electronic device according to one aspect includes a solar cell and a secondary battery. The solar cell includes a transparent electrode, an electron transport layer formed on the electrode, a light absorption layer formed on the electron transport layer and containing an electron collector and a dye, a counter electrode disposed opposite to the electrode, and a substrate provided with the counter electrode. The secondary battery is disposed on the circuit board in a state where the solar cells are stacked.

Advantages of the Invention

[0007] According to the present disclosure, it is possible to provide a small electronic device that operates using the power of the secondary battery while charging the secondary battery with the solar cell.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described with reference to the drawings. FIG. 1 is a diagram showing an example of the configuration of an electronic device according to an embodiment. The electronic device 1 in FIG. 1 is, for example, a self - contained sensor. The self - contained sensor is installed indoors or outdoors and detects information on the environment around the installation location, such as temperature, humidity, atmospheric pressure, vibration, and gas. The self - contained sensor operates on electric power from a secondary battery charged by a solar cell mounted on the self - contained sensor.

[0010] The electronic device 1 in FIG. 1 includes a solar cell 10, a secondary battery 20, a charging circuit 30, a power supply circuit 40, a sensor unit 50, and an MCU (Micro Control Unit) 60.

[0011] The solar cell 10 is a battery that generates electricity by the incidence of light. An example of the solar cell 10 is a dye - sensitized solar cell (DSC). The configuration of the solar cell 10 will be described in detail later.

[0012] The secondary battery 20 is, for example, a lithium - ion battery and stores electric power for the operation of the electronic device 1. The secondary battery 20 is charged by the electric power generated by the solar cell 10. Here, the secondary battery 20 in the embodiment is, for example, a flat - plate battery. From the perspective of miniaturization of the electronic device 1, it is desirable that the secondary battery 20 be a thin plate.

[0013] The charging circuit 30 includes, for example, a DC - DC converter, converts the electric power generated by the power generation of the solar cell 10 into electric power of a magnitude suitable for charging the secondary battery 20, and charges the secondary battery 20 with the converted electric power. The charging circuit 30 may be configured to be able to charge the secondary battery 20 also with electric power supplied from outside the electronic device 1.

[0014] The power supply circuit 40 includes, for example, a DC - DC converter, converts the electric power generated by the secondary battery 20 into electric power of a magnitude suitable for the respective operations of the sensor unit 50 and the MCU 60, and supplies the converted electric power to the sensor unit 50 and the MCU 60 respectively.

[0015] The sensor unit 50 is a sensor that detects various types of information such as a temperature sensor, a humidity sensor, a pressure sensor, a vibration sensor, and a gas sensor. The detection target of the sensor unit 50 is not particularly limited. The sensor unit 50 can operate based on the power supplied from the power circuit 40. The sensor unit 50 may be composed of a single sensor or may be composed of a plurality of sensors. The plurality of sensors may be a plurality of sensors of the same type or may be a plurality of different types of sensors.

[0016] The MCU 60 is a control circuit of the electronic device 1. The MCU 60 includes a processor, a memory, a wireless transmission circuit, etc. The MCU 60 can operate based on the power supplied from the power circuit 40. The MCU 60 performs, for example, periodically transmitting the information detected by the sensor unit 50 to a server (not shown) etc.

[0017] FIG. 2 is a diagram showing the arrangement on the circuit board 70 of the solar cell 10, the secondary battery 20, the charging circuit 30, the power circuit 40, the sensor unit 50, and the MCU 60 in the electronic device 1. FIG. 2 is a view of the circuit board 70 seen from above. Further, FIG. 3 is a side view of the circuit board 70 seen from the side S of FIG. 2.

[0018] In the embodiment, the solar cell 10 is disposed at an internal position of the electronic device 1 that can receive light incident through an incident window (not shown) provided in the exterior portion of the electronic device 1. And the secondary battery 20 is disposed under the solar cell 10. In other words, the secondary battery 20 is disposed on the circuit board 70 in a state where the solar cells 10 are stacked. As will be described later, an insulating substrate such as a glass substrate is disposed on the lower surface of the solar cell 10. Therefore, even if the secondary battery 20 is disposed under the solar cell 10, the solar cell 10 and the secondary battery 20 are not directly electrically connected.

[0019] Near the solar cell 10 and the secondary battery 20, a charging circuit 30 and a power supply circuit 40 are provided. When the secondary battery 20 is being charged, the secondary battery 20 is connected to the solar cell 10 via the charging circuit 30. When the sensor unit 50 is operating, the secondary battery 20 is connected to the sensor unit 50 via the power supply circuit 40.

[0020] Also, the power supply circuit 40 is connected to the sensor unit 50. In FIG. 2, the sensor unit 50 has n (n is a natural number) sensors 501, 502, …, 50n. The power supply circuit 40 can be connected to each of the respective sensors 501, 502, …, 50n. As described above, the sensors 501, 502, …, 50n may be of the same type or different types. The sensors 501, 502, …, 50n are connected to the MCU 60.

[0021] Here, the charging circuit 30 does not necessarily have to be provided near the secondary battery 20 as long as electrical connection between the solar cell 10 and the secondary battery 20 is ensured. Similarly, the power supply circuit 40 does not necessarily have to be provided near the solar cell 10 and the secondary battery 20 as long as electrical connection between the power supply circuit 40 and the secondary battery 20 is ensured. Furthermore, the positions of the sensor unit 50 and the MCU 60 may be changed as appropriate.

[0022] FIG. 4 is a cross-sectional view showing an example of the configuration of the solar cell according to the embodiment. FIG. 4 shows a cross-sectional view when the solar cell 10 is a dye-sensitized solar cell.

[0023] An example of a dye-sensitized solar cell is a dye-sensitized solar cell module having a Z-type structure in which a plurality of dye-sensitized solar cell units U1, U2, U3, U4 are connected in series. In FIG. 4, the number of units is four. The number of units is not limited to four. Also, the four units of the dye-sensitized solar cell do not necessarily have to be connected in series.

[0024] As shown in FIG. 4, each unit U1, U2, U3, U4 of the dye-sensitized solar cell is formed between a first substrate 11 and a second substrate 12. The first substrate 11 is a transparent substrate such as a glass substrate. The second substrate 12 is arranged to face the first substrate 11. The second substrate 12 is a transparent substrate such as a glass substrate, similar to the first substrate 11.

[0025] An electrode 13 is formed at the position of each unit of the first substrate 11. The interval between the electrodes 13 is, for example, an interval such that there is no influence such as leakage current between adjacent electrodes. The electrode 13 is formed of a transparent conductive oxide film (TCO) such as indium tin oxide (ITO) or fluorine-doped tin oxide (FTO). Each electrode 13 is used as the anode electrode of the corresponding unit. Also, of the units U1 and U4 which are the end units in the dye-sensitized solar cell, the electrode 13 formed in the unit U4 in FIG. 4 is drawn out to the outside of the dye-sensitized solar cell. The electrode 13 drawn out to the outside is connected to the counter electrode 14 via the vertical conduction sealing material 19a. This counter electrode 14 is drawn out to the outside of the dye-sensitized solar cell. A terminal 131 is formed on the drawn-out counter electrode 14. A wiring is drawn out from the terminal 131. This wiring is connected to one end of a load (not shown). The terminal 131 may be formed on the electrode 13 drawn out to the outside.

[0026] At the position of each unit of the second substrate 12, a counter electrode 14 is formed. The interval between the counter electrodes 14 is, for example, an interval such that there is no influence such as leakage current between adjacent electrodes. The counter electrode 14 is formed of a transparent conductive oxide film (TCO) such as indium tin oxide (ITO) or fluorine-doped tin oxide (FTO), similar to the electrode 13. Each counter electrode 14 is used as the cathode electrode of the corresponding unit. Also, of the units U1 and U4 which are the end units in the dye-sensitized solar cell, the counter electrode 14 formed on the unit U1 in FIG. 4 is drawn out to the outside of the dye-sensitized solar cell. A terminal 141 is formed on the drawn-out counter electrode 14. Wiring is drawn out from the terminal 141. This wiring is connected to the other end of a load (not shown). The terminal 141 may be formed on the side of the first substrate 11 by using an upper and lower conduction sealing material 19a.

[0027] An electron transport layer 15 is formed on the electrode 13 that constitutes the anode electrode of each unit. The electron transport layer 15 is composed of a metal oxide film of titanium oxide (TiO x ). The electron transport layer 15 can be provided to suppress the loss caused by the electrode 13 composed of a TCO having a higher resistance than that of a metal. Also, by forming the electron transport layer 15, the adhesion of the light absorption layer 16 further formed on the electron transport layer 15 is improved.

[0028] A light absorption layer 16 is formed on each electron transport layer 15. The light absorption layer 16 is a layer formed by adsorbing a dye on an electron collector. The electron collector is, for example, an aggregate of minute oxide semiconductors, for example, titanium oxide (TiO 2 ). The dye is, for example, a ruthenium (Ru) dye (RU) (such as N719 dye). The electron collector is not limited to titanium oxide, and may be, for example, zinc oxide, tin oxide, tungsten oxide, niobium oxide, indium oxide, and composites thereof. Also, the dye is not limited to the N719 dye. For example, as ruthenium-based dyes, N3 dye, BlackDye, and as pure organic dyes, D149, xanthene, PVK, merocyanine, oxazine, etc. may be used.

[0029] A catalyst layer 17 is formed on the counter electrode 14 that constitutes the cathode electrode of each unit. The catalyst layer 17 is, for example, a platinum layer.

[0030] An electrolytic solution 18 is filled between the light absorption layer 16 and the catalyst layer 17 of each unit. As the solvent of the electrolytic solution 18, for example, acetonitrile, methoxyacetonitrile, ethylene carbonate, etc. can be used. As the solute of the electrolytic solution 18, for example, iodine (I 2 )), 1,2-dimethyl-3-n-propylimidazolium iodide (DMPImI), lithium iodide (LiI), 4-tert-butylpyridine (TBP), etc. can be used. As shown in FIG. 4, the electrolytic solution 18 is partitioned by upper and lower conduction sealing materials 19a provided at the boundary positions between the respective units U1 and U2, between the unit U2 and the unit U3, and between the unit U3 and the unit U4. The upper and lower conduction sealing materials 19a are constituted by containing conductive fine particles as a conductive material containing metal particles in a resin excellent in solvent resistance such as an acrylic resin and an olefin resin. The upper and lower conduction sealing materials 19a bond the first substrate 11 and the second substrate 12 and are provided between the opposing electrodes to conduct between the units.

[0031] An external sealing material 19 is formed at the outermost peripheral part of the dye-sensitized solar cell. The external sealing material 19 bonds the first substrate 11 and the second substrate 12 and prevents the electrolytic solution 18 from leaking to the outside. That is, the electrolytic solution 18 is sealed by the first substrate 11, the second substrate 12, the upper and lower conduction sealing materials 19a, and the external sealing material 19. The external sealing material 19 is constituted by a resin excellent in solvent resistance such as an acrylic resin and an olefin resin.

[0032] As shown in FIGS. 2 and 3, a secondary battery 20 is disposed under the solar cell 10. Here, if the secondary battery 20 has an exterior having light reflectivity such as metal, the exterior of the secondary battery 20 functions as a reflection and diffusion member that reflects and diffuses the light transmitted through the second substrate 12 without being absorbed by the light absorption layer 16 and returns it to the light absorption layer 16 according to the power generation principle described later. Further, since the second substrate 12 is, for example, a glass substrate, even if the exterior of the secondary battery 20 is made of metal or the like and the second substrate 12 and the exterior of the secondary battery 20 are in contact with each other, the solar cell 10 and the secondary battery 20 do not short-circuit.

[0033] FIG. 5 is a diagram for explaining the power generation principle in one unit of a dye-sensitized solar cell. Further, in the following example, it is assumed that the electron collector is titanium oxide (TiO 2 ), the dye is a ruthenium (Ru) dye, and the electrolytic solution 18 is an iodine (I) electrolytic solution.

[0034] First, when light is incident on the dye-sensitized solar cell, the light is absorbed by the dye 16a formed on the substrate. The dye 16a is excited by absorbing light. The reaction formula is shown, for example, by the following formula (1). Ru→Ru + +e - (1)

[0035] The electrons (e - ) emitted from the excited dye 16a are injected into an electron collector 16b composed of, for example, porous titanium oxide (TiO 2 ). The electrons injected into the electron collector 16b move to the electrode 13 which is an anode electrode.

[0036] On the other hand, the dye 16a that has lost electrons (e - ) is supplied with electrons from, for example, iodide ions (I - ) in the electrolytic solution 18. The iodide ions (I - ) in the electrolytic solution 18 supply electrons (e - ) to the dye 16a and become triiodide ions (I 3 - ). The reaction formulas are shown, for example, by the following formulas (2) and (3). Ru + e - → Ru(2) 3I - → I 3 - + 2e - (3)

[0037] The triiodide ion (I 3 - ) generated by such an oxidation reaction attempts to receive electrons (e - ) from the counter electrode 14 which is the cathode electrode. At this time, a potential difference is generated between the counter electrode 14 and the electrode 13. If a load is connected between the counter electrode 14 and the electrode 13, the electrons that have moved to the electrode 13 move through the load to the counter electrode 14. Then, the electrons that have reached the counter electrode 14 are absorbed by the triiodide ion (I 3 - ). By such a reduction reaction, the triiodide ion (I 3 - ) returns to the iodide ion (I - ). The reaction formula is shown by, for example, the following formula (4). I 3 - + 2e - → 3I - (4)

[0038] By repeating the above oxidation-reduction reaction, the unit of the dye-sensitized solar cell generates electricity. For such an oxidation-reduction reaction to occur, the energy level of the excited-state dye 16a needs to be higher than the energy level of the electron collector 16b, and the energy level of the ground-state dye 16a needs to be lower than the energy level of the electrolytic solution 18.

[0039] Here, the light incident on the dye-sensitized solar cell is basically absorbed by the dye 16a that constitutes the light absorption layer 16. On the other hand, there may be light among the light incident on the dye-sensitized solar cell that is not absorbed by the dye 16a. The light not absorbed by such dye 16a will pass through the second substrate 12 configured as a transparent substrate. The light passing through such second substrate 12 becomes a factor that reduces the power generation efficiency of the dye-sensitized solar cell. In the embodiment, the power generation efficiency of the dye-sensitized solar cell is improved by returning the light passing through the second substrate 12 to the light absorption layer 16 by means of the secondary battery 20 provided with an exterior having light reflectivity. Here, in the embodiment, the second substrate 12 does not necessarily have to be a transparent substrate such as a glass substrate. Similarly, in the embodiment, the counter electrode 14 does not necessarily have to be a transparent electrode. However, when the second substrate 12 and the counter electrode 14 are not transparent, the exterior of the secondary battery 20 does not function as a reflection and diffusion member.

[0040] As described above, according to the embodiment, the secondary battery 20 in a state where the solar cells 10 are stacked is disposed on the circuit board 70. Thereby, the occupied area of the solar cells 10 and the secondary battery 20 on the circuit board 70 substantially becomes the area of only the secondary battery 20. For this reason, a margin is created in the area where the solar cells 10 should originally be disposed, and other circuits such as the charging circuit 30 and the power supply circuit 40 can be disposed in this area. Therefore, the electronic device 1 can be miniaturized while mounting the solar cells 10 and the secondary battery 20.

[0041] Also, by stacking the solar cells 10 on the secondary battery 20, light can be made incident on the first substrate 11 which is the light incident surface of the solar cells 10. Note that a film or the like for the purpose of preventing scattering and UV cut may be formed on the light incident surface side of the first substrate 11.

[0042] Hereinafter, a modification example of the embodiment will be described. (Modification Example 1) In the above-described embodiment, the exterior of the secondary battery 20 is assumed to have light reflectivity. On the other hand, various types of information such as lot numbers may be printed on the exterior of commercially available secondary batteries 20. Even if such various types of information are printed, a secondary battery having a reflectance of about 50% can function as a reflection diffusion member.

[0043] (Modification 2) In the above-described embodiment, the solar cell 10, the secondary battery 20, the charging circuit 30, the power supply circuit 40, the sensor unit 50, and the MCU 60 are arranged on the same surface of the circuit board 70. On the other hand, as shown in FIG. 6, one sensor 501 of the sensor unit 50, for example, which is a part of the elements, may be arranged on the back surface of the circuit board 70. That is, as long as the solar cell 10 is stacked on the secondary battery 20 and the conduction between the solar cell 10, the secondary battery 20, the charging circuit 30, the power supply circuit 40, the sensor unit 50, and the MCU 60 is achieved, the solar cell 10, the secondary battery 20, the charging circuit 30, the power supply circuit 40, the sensor unit 50, and the MCU 60 can be arranged at arbitrary positions on the circuit board 70.

[0044] As in Modification 3, by arranging some of the elements of the electronic device 1 on the back surface of the circuit board 70, further miniaturization of the electronic device 1 is expected.

[0045] (Modification 3) In the above-described embodiment, the solar cell 10 is directly stacked on the secondary battery 20. That is, the solar cell 10 and the secondary battery 20 are in direct contact. In contrast, as shown in FIG. 7, a light reflection member 80 may be interposed between the solar cell 10 and the secondary battery 20. The light reflection member 80 may be in close contact with the solar cell 10 and the secondary battery 20, or may not be in close contact. That is, an air layer may or may not be interposed between the solar cell 10 and the light reflection member 80 and between the light reflection member 80 and the secondary battery 20. The light reflection member 80 is not particularly limited, and can be, for example, white paper. Similar to the case where the exterior of the secondary battery 20 described above is made light-reflective, the light reflection member 80 can function as a reflection and diffusion member that reflects and diffuses the light that has passed through the second substrate 12 without being absorbed by the light absorption layer 16 and returns it to the light absorption layer 16. In particular, when white paper is adopted as the light reflection member 80, since the paper is an insulating material, it is also effective in preventing short circuits between the solar cell 10 and the secondary battery 20 due to their stacking.

[0046] (Modification 4) In the above-described embodiment, the number of secondary batteries mounted on one electronic device is assumed to be one. In contrast, the number of secondary batteries mounted on one electronic device may be two or more. Also, in the above-described embodiment, the secondary battery is assumed to be flat. In contrast, the secondary battery may have a shape other than flat. For example, the secondary battery may be cylindrical as shown in FIG. 8. In addition, the secondary battery may be prismatic or the like.

[0047] (Modification 5) In the above-described embodiments, the four units U1, U2, U3, and U4 constituting the solar cell 10 are arranged side by side in a straight line. In this case, the terminals 131 and 141 are formed at both ends of the second substrate 12 as shown in FIG. 3. On the other hand, the four units U1, U2, U3, and U4 may be arranged so as to be bent as shown in FIG. 9. In this case, the terminals 131 and 141 may be formed at one end of the second substrate 12 as shown in FIG. 9. Here, the terminals of the commercially available secondary battery 20 are often formed at one end. Therefore, by forming the terminals 131 and 141 of the solar cell 10 at one end of the second substrate 12 and arranging the solar cell 10 and the secondary battery 20 such that the side where the terminals of the solar cell 10 are arranged is different from the side where the terminals of the secondary battery 20 are arranged, the possibility of contact between the terminals of the solar cell 10 and the terminals of the secondary battery 20 due to the solar cell 10 being stacked on the secondary battery 20 can be further reduced. Thereby, the possibility of a short circuit between the solar cell 10 and the secondary battery 20 can be further reduced.

[0048] (Other Modification Examples) Other modification examples will be described. In the above-described embodiments and modification examples, application examples of a liquid-type electrolyte to a dye-sensitized solar cell are shown. On the other hand, since the secondary battery 20 may be installed on the back surface of the solar cell, the configurations of the above-described embodiments and modification examples can also be applied to configurations other than the dye-sensitized solar cell with a liquid-type electrolyte. For example, the dye-sensitized solar cell may be a dye-sensitized solar cell with a solid-type electrolyte. In the case of a dye-sensitized solar cell with a solid-type electrolyte, the only difference is that a solid electrolyte layer is interposed between the light absorption layer 16 and the catalyst layer 17 of each unit instead of the electrolyte 18. The solid electrolyte layer may be, for example, a gel obtained by gelling the electrolyte 18 with a gelling agent or the like.

[0049] Further, as a further modification example, the configurations of the above-described embodiments and modification examples can also be applied to various solar cells other than dye-sensitized solar cells such as perovskite solar cells. For example, in the case of a perovskite solar cell, the solid electrolyte layer may be replaced with a perovskite crystal layer.

[0050] In the above-described embodiments and modifications, the first substrate 11 and the second substrate 12 are assumed to be transparent substrates such as glass substrates. On the other hand, the first substrate 11 and the second substrate 12 may be flexible substrates. In this case, the configurations of the above-described embodiments and modifications can also be applied to a monolithic structure in which electrodes and the like are formed only on one of the first substrate 11 and the second substrate 12.

[0051] The present invention is not limited to the above embodiments, and various modifications can be made without departing from the gist thereof at the implementation stage. Also, the respective embodiments may be implemented in appropriate combinations, and in that case, the combined effects can be obtained. Furthermore, the above embodiments include various inventions, and various inventions can be extracted by combinations selected from a plurality of disclosed constituent elements. For example, even if some constituent elements are deleted from all the constituent elements shown in the embodiments, if the problem can be solved and the effects can be obtained, the configuration from which these constituent elements are deleted can be extracted as an invention.

Explanation of Reference Numerals

[0052] 1 Electronic device, 10 Solar cell, 11 First substrate, 12 Second substrate, 13 Electrode, 14 Counter electrode, 15 Electron transport layer, 16 Light absorption layer, 17 Catalyst layer, 18 Electrolyte, 19 External sealing material, 19a Vertical conduction sealing material, 20 Secondary battery, 30 Charging circuit, 40 Power supply circuit, 50 Sensor unit, 60 MCU, 70 Circuit board, 80 Light reflection member.

Claims

1. A transparent electrode, an electron transport layer formed on the electrode; a light absorbing layer formed on the electron transport layer and including an electron collector and a dye; a counter electrode disposed opposite the electrode; A substrate on which the counter electrode is provided; A solar cell comprising: a secondary battery that is disposed on a circuit board with the solar cell stacked thereon; An electronic device having the

2. The electronic device according to claim 1 , further comprising an element that is arranged on a surface of the circuit board opposite to the surface on which the secondary battery is arranged, and that operates using power from the secondary battery.

3. The electronic device according to claim 1 , further comprising a light reflecting member provided between the secondary battery and the solar cell.

4. The electronic device according to claim 1 , wherein the secondary battery has any one of a flat plate shape, a cylindrical shape, and a prismatic shape.

5. The electronic device according to claim 1 , wherein a terminal of the solar cell and a terminal of the secondary battery are oriented in different directions.

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