Electronic apparatus

Abstract

To provide an electronic apparatus in which a solar cell with further improved power generation performance is installed.SOLUTION: The 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 that is formed on the electron transport layer and contains an electron collector and a dye, a transparent counter electrode arranged to face the electrode, and a transparent substrate on which the counter electrode is provided. The secondary battery is arranged on a surface of the substrate on an opposite side to a surface of the substrate on which the counter electrode is provided, and has a light-reflective outer covering.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to an electronic device equipped with a solar cell. [Background technology]

[0002] With the advancement of IoT (Internet of Things) technology, the use of autonomous sensors as electronic devices in edge devices is expected to expand. Autonomous sensors are equipped with secondary batteries such as lithium-ion batteries, and while performing sensing using the power of these secondary batteries, they also autonomously charge the secondary batteries. Solar cells are used as a means of charging secondary batteries without a power supply. Further improvements in the power generation performance of solar cells are expected to enable efficient charging of secondary batteries. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-347003 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide an electronic device equipped with a solar cell with further improved power generation performance. [Means for solving the problem]

[0005] An electronic device according to one embodiment 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 transparent counter electrode disposed opposite the electrode, and a transparent substrate on which the counter electrode is disposed. The secondary battery is disposed on the surface of the substrate opposite the surface on which the counter electrode is disposed, and has a light-reflective exterior. Effect of the Invention

[0006] According to the present disclosure, it is possible to provide an electronic device equipped with a solar cell with further improved power generation performance. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating an example of a configuration of an electronic device according to an embodiment. [Diagram 2] FIG. 2 is a perspective view of the electronic device showing the positional relationship between the solar cell and the secondary battery in the embodiment. [Diagram 3] FIG. 3 is a cross-sectional view showing an example of the configuration of a solar cell according to an embodiment. [Figure 4] FIG. 4 is a diagram for explaining the principle of power generation in one unit of the dye-sensitized solar cell. [Diagram 5] FIG. 5 is a graph showing the short-circuit current Isc and maximum output Pmax calculated from the measurement results of the IV characteristics of a dye-sensitized solar cell that does not use a reflective / diffusing member and a dye-sensitized solar cell that uses a secondary battery as a reflective / diffusing member. [Figure 6] FIG. 6 is a diagram showing a secondary battery according to the second modification. [Figure 7] FIG. 7 is a diagram showing a secondary battery according to the third modification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment 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 standalone environmental sensor. The standalone environmental sensor is installed indoors or outdoors, and detects information on the surrounding environment of the place where it is installed, such as temperature, humidity, and air pressure. The standalone environmental sensor operates using power from a secondary battery that is charged by a solar cell mounted on the standalone environmental sensor.

[0009] The electronic device 1 in FIG. 1 includes a solar cell 10, a secondary battery 20, transformer circuits 30a and 30b, and a sensor unit .

[0010] The solar cell 10 is a cell that generates electricity when light is incident on it. 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.

[0011] The secondary battery 20 is, for example, a lithium ion battery, and stores power for operating the electronic device 1. The secondary battery 20 is charged by power generated by the solar cell 10. Here, the secondary battery 20 in the embodiment is, for example, a flat-plate battery having a light-reflective exterior made of metal or the like. From the viewpoint of miniaturizing the electronic device 1, it is preferable that the secondary battery 20 is a thin plate.

[0012] The transformer circuit 30a is, for example, a DC-DC converter, and transforms the voltage generated by the power generation of the solar cell 10 into a voltage of a magnitude suitable for charging the secondary battery 20. The transformer circuit 30b is, for example, a DC-DC converter, and transforms the voltage of the secondary battery 20 into a voltage of a magnitude suitable for the operation of the sensor unit 40.

[0013] The sensor unit 40 is a sensor that detects various types of environmental information, such as a temperature sensor, a humidity sensor, and an air pressure sensor. The environmental information to be detected by the sensor unit 40 is not particularly limited. The sensor unit 40 can operate based on the power supplied from the transformer circuit 30b.

[0014] FIG. 2 is a perspective view of the electronic device 1 showing the positional relationship between the solar cell 10 and the secondary battery 20 in the embodiment.

[0015] In the embodiment, the solar cell 10 is disposed at an internal position of the electronic device 1 where it can receive light incident through an incident window (not shown) provided on the exterior of the electronic device 1. The secondary battery 20 is disposed on the exit optical path of the light from the solar cell 10. For example, the secondary battery 20 is disposed so as to face the light exit surface of the solar cell 10. The light exit surface of the solar cell 10 is a surface that faces the light entrance surface of the solar cell 10. As shown in FIG. 2, the secondary battery 20 is desirably disposed so as to cover the entire surface of the light exit surface of the solar cell 10.

[0016] The transformer circuits 30a and 30b and the sensor unit 40 are provided, for example, on a substrate arranged to face the rear surface of the secondary battery 20 opposite the surface facing the solar cell 10. Here, the transformer circuits 30a and 30b and the sensor unit 40 do not necessarily have to be provided on a substrate arranged to face the rear surface of the secondary battery 20 opposite the surface facing the solar cell 10. As long as electrical connection between the transformer circuits 30a and 30b and the sensor unit 40 and the secondary battery 20 is ensured, the transformer circuits 30a and 30b and the sensor unit 40 can be provided at any position relative to the secondary battery 20.

[0017] Fig. 3 is a cross-sectional view showing an example of the configuration of a solar cell according to an embodiment of the present invention, in which the solar cell 10 is a dye-sensitized solar cell.

[0018] The dye-sensitized solar cell is a dye-sensitized solar cell module having a plurality of dye-sensitized solar cell units U1 and U2. In FIG. 3, the number of units is two. The number of units is not limited to two. In FIG. 3, the unit U1 and the unit U2 are not electrically connected. On the other hand, the unit U1 and the unit U2 may be connected in series or in parallel.

[0019] As shown in FIG. 3, each unit U1 and U2 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 disposed so as 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. Here, in the example of FIG. 3, light L1 is incident on the dye-sensitized solar cell from the side of the first substrate 11. That is, in the example of FIG. 3, the first substrate 11 becomes the light incident surface of the solar cell 10 in FIG. 2.

[0020] In the following, the description will be continued assuming that each unit has the same configuration. Electrodes 13 are formed at the position of each unit on the first substrate 11. The electrodes 13 are spaced apart such that there is no influence of leakage current between adjacent electrodes. The electrodes 13 are 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 an anode electrode for the corresponding unit.

[0021] Counter electrodes 14 are formed at the positions of the respective units on the second substrate 12. The intervals between the counter electrodes 14 are set to a level that does not cause effects such as leakage current between adjacent electrodes. Like the electrode 13, the counter electrodes 14 are formed of a transparent conductive oxide film (TCO) such as indium tin oxide (ITO) or fluorine-doped tin oxide (FTO). Each counter electrode 14 is used as a cathode electrode for the corresponding unit.

[0022] 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 made of titanium oxide (TiO x The electron transport layer 15 is made of a metal oxide film such as TCO, which has a higher resistance than metal. The electron transport layer 15 can be provided to suppress loss due to the electrode 13 made of TCO, which has a higher resistance than metal. In addition, the formation of the electron transport layer 15 improves the adhesion of the light absorbing layer 16, which is further formed on the electron transport layer 15.

[0023] A light absorbing layer 16 is formed on each of the electron transport layers 15. The light absorbing layer 16 is a layer formed by adsorbing a dye to an electron collector. The electron collector is, for example, an aggregate of minute oxide semiconductors, for example, titanium oxide (TiO2). The dye is, for example, a ruthenium (Ru) dye (RU) (N719 dye, etc.). The electron collector is not limited to titanium oxide, but may be, for example, zinc oxide, tin oxide, tungsten oxide, niobium oxide, indium oxide, and a complex thereof. In addition, the dye is not limited to N719 dye. For example, N3 dye and BlackDye may be used as ruthenium-based dyes, and D149, xanthene, PVK, merocyanine, oxazine, etc. may be used as pure organic dyes.

[0024] 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.

[0025] An electrolyte solution 18 is filled between the light absorbing layer 16 and the catalyst layer 17 of each unit. As a solvent for the electrolyte solution 18, for example, acetonitrile, methoxyacetonitrile, ethylene carbonate, etc. can be used. As a solute for the electrolyte solution 18, for example, iodine (I2), 1,2-dimethyl-3-n-propylimidazolium iodide (DMPImI), lithium iodide (LiI), 4-tert-butylpyridine (TBP), etc. can be used. As shown in FIG. 3, the electrolyte solution 18 is partitioned by a sealant 19 provided at the boundary position between the unit U1 and the unit U2. Furthermore, a sealant 19 is also formed on the outermost periphery of the dye-sensitized solar cell. The sealant 19 bonds the first substrate 11 and the second substrate 12 together and prevents the electrolyte solution 18 from leaking out to the outside. The sealant 19 can be a resin with excellent solvent resistance, such as an acrylic resin or an olefin resin. Here, in FIG. 3, the sealing material 19 may be mixed with a metal to make it conductive, and the electrode 13 of the unit U1 and the counter electrode 14 of the unit U2 may be electrically connected via the sealing material, thereby connecting the unit U1 and the unit U2 in series.

[0026] As shown in Fig. 2, the secondary battery 20 is disposed so as to face the light exit surface of the solar cell 10. That is, in the example of Fig. 3, the second substrate 12 becomes the light exit surface of the solar cell 10 in Fig. 2. As described above, the exterior of the secondary battery 20 has light reflectivity. For this reason, the exterior of the secondary battery 20 can function as a reflecting / diffusing member that reflects and diffuses light that has not been absorbed by the light absorbing layer 16 and has passed through the second substrate 12, as shown by the arrow L2, and returns the light to the light absorbing layer 16, according to the power generation principle described later.

[0027] 4 is a diagram for explaining the power generation principle in one unit of a dye-sensitized solar cell. In the following example, the electron collector is titanium oxide (TiO2), the dye is a ruthenium (Ru) dye, and the electrolyte 18 is an iodine (I) electrolyte.

[0028] 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 the light. The reaction formula is, for example, shown in the following formula (1). Ru → Ru + +e - (1)

[0029] Electrons emitted from the excited dye 16a (e - The electrons injected into the electron collector 16b move to the electrode 13, which is an anode electrode.

[0030] On the other hand, electrons (e - The dye 16a that has lost the ion exchange function reacts with, for example, iodide ions (I - ) in electrolyte 18. - ) is an electron (e - ) to dye 16a, triiodide ion (I3 - The reaction formula is shown in the following formulas (2) and (3). Ru+e - →Ru (2) 3I - →I3- +2e - (3)

[0031] The triiodide ion (I3 - ) is transported from the cathode electrode 14 to the counter electrode 14 by electrons (e - ) is received by the counter electrode 14. 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 will move through the load to the counter electrode 14. Then, the electrons that have reached the counter electrode 14 will be converted into triiodide ions (I3 - ) is absorbed by the iodide ion (I3 - ) is the iodide ion (I - ) The reaction formula is shown, for example, in the following formula (4). I3 - +2e - →3I - (4)

[0032] The above-mentioned redox reaction is repeated to generate electricity in the dye-sensitized solar cell unit. For this redox reaction to occur, the energy level of the excited dye 16a must be higher than the energy level of the electron collector 16b, and the energy level of the ground dye 16a must be lower than the energy level of the electrolyte 18.

[0033] Next, the reflection / diffusion operation by the secondary cell 20 will be described. As described above, the light incident on the dye-sensitized solar cell is basically absorbed by the dye 16a constituting the light absorbing layer 16. On the other hand, there may be some light that is not absorbed by the dye 16a among the light incident on the dye-sensitized solar cell. Such light that is not absorbed by the dye 16a passes through the second substrate 12 as the light exit surface. Such light that passes through the second substrate 12 is 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 that passes through the second substrate 12 to the light absorbing layer 16 by the secondary cell 20 having a light-reflective exterior.

[0034] FIG. 5 is a graph showing the short-circuit current Isc and maximum output Pmax calculated from the measurement results of the IV characteristics of a dye-sensitized solar cell that does not use a reflective / diffusing member and a dye-sensitized solar cell that uses a secondary battery as a reflective / diffusing member. FIG. 5 shows the results when the dye-sensitized solar cell is irradiated with 1000 lux of light from an LED light source. The light of 1000 lux is low illuminance light that simulates indoor light. The short-circuit current Isc and maximum output Pmax in FIG. 5 are expressed as a ratio when the short-circuit current Isc and maximum output Pmax of the dye-sensitized solar cell that does not use a reflective / diffusing member are set to 1, respectively.

[0035] The short-circuit current Isc corresponds to the current when the applied voltage is 0V. A large Isc indicates that the power generation performance of the dye-sensitized solar cell, i.e., the maximum output Pmax, is high. As shown in FIG. 5, when a secondary battery is used as a reflective / diffusing member, both the short-circuit current Isc and the maximum output Pmax are higher than when a secondary battery is not used as a reflective / diffusing member. In other words, it can be seen that the power generation performance of the dye-sensitized solar cell is improved by using a secondary battery as a reflective / diffusing member.

[0036] As described above, according to the embodiment, the secondary battery 20 having a light-reflective exterior is disposed on the back surface of the substrate opposite the substrate on the light-incident side of the solar cell. Light not absorbed by the dye 16a of the light-absorbing layer 16 is returned to the light-absorbing layer 16, thereby improving power generation performance. In addition, the secondary battery 20 is disposed on the back surface of the substrate opposite the substrate on the light-incident side. Therefore, the secondary battery 20 can be disposed without changing the configuration of an existing solar cell. Therefore, the solar cell of the embodiment can improve power generation performance with a simple configuration that does not require a new member such as a dedicated reflector.

[0037] Modifications of the embodiment will be described below. (Variation 1) In the above-described embodiment, the exterior of the secondary battery 20 is assumed to have light reflectivity. On the other hand, various information such as a lot number may be printed on the exterior of a commercially available secondary battery 20. Even if such various information is printed on the exterior, the secondary battery can function as a reflective / diffusing member as long as it has a reflectance of about 50%.

[0038] (Variation 2) In the above-described embodiment, one electronic device is equipped with one secondary battery. However, two or more secondary batteries may be equipped with one electronic device. In this case, as shown in FIG. 6, two or more secondary batteries may be arranged to cover the solar cell 10. Note that in FIG. 6, illustration of the transformer circuits 30a and 30b and the board on which the sensor unit 40 is mounted is omitted. Also, in FIG. 6, three secondary batteries 20a, 20b, and 20c are arranged on the light exit surface side of the solar cell 10. Of course, the number of secondary batteries arranged on the light exit surface side is not limited to three.

[0039] By arranging a plurality of secondary batteries for solar cell 10 as shown in FIG. 6, secondary batteries can be arranged even on a solar cell having a large area.

[0040] (Variation 3) In the above-described embodiment, the secondary battery is assumed to have a flat plate shape. However, the secondary battery may have a shape other than a flat plate shape. For example, the secondary battery may have a cylindrical shape as shown in FIG. 7. Alternatively, the secondary battery may have a prismatic shape or the like.

[0041] (Other variations) Other modified examples will be described. In the above-mentioned embodiment and modified examples, examples of application to a dye-sensitized solar cell with a liquid electrolyte are shown. In contrast, since the secondary battery 20 only needs to be installed on the back surface of the solar cell, the configurations of the above-mentioned embodiment and modified examples can be applied to configurations other than the dye-sensitized solar cell with a liquid electrolyte. For example, the dye-sensitized solar cell may be a dye-sensitized solar cell with a solid electrolyte. In the case of a dye-sensitized solar cell with a solid 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, rather than the electrolyte 18. The solid electrolyte layer may be, for example, the electrolyte 18 gelled by a gelling agent or the like.

[0042] As a further modification, the configurations of the above-described embodiment and modification may be applied to various solar cells other than dye-sensitized solar cells such as perovskite solar cells, etc. For example, in the case of a perovskite solar cell, the solid electrolyte layer may be replaced with a perovskite crystal layer.

[0043] In the above-described embodiment and modified examples, the first substrate 11 and the second substrate 12 are transparent substrates such as glass substrates. In contrast, the first substrate 11 and the second substrate 12 may be flexible substrates. In this case, the configurations of the above-described embodiment and modified examples may be applied to a monolithic structure in which electrodes and the like are formed on only one of the first substrate 11 and the second substrate 12.

[0044] The present invention is not limited to the above-mentioned embodiment, and various modifications can be made in the implementation stage without departing from the gist of the invention. In addition, the embodiments may be implemented in appropriate combination, and in that case, the combined effect can be obtained. Furthermore, the above-mentioned embodiment includes various inventions, and various inventions can be extracted by combinations selected from the multiple components disclosed. For example, if the problem can be solved and the effect can be obtained even if some components are deleted from all the components shown in the embodiment, the configuration from which the components are deleted can be extracted as an invention. [Explanation of symbols]

[0045] 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 sealing material, 20, 20a, 20b, 20c secondary battery, 30a, 30b transformer circuit, 40 sensor unit.

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 transparent counter electrode disposed opposite the electrode; A transparent substrate on which the counter electrode is provided; A solar cell comprising: a secondary battery having a light-reflective exterior disposed on a surface of the substrate opposite to a surface on which the counter electrode is provided; An electronic device having the

2. The electronic device according to claim 1 , wherein the secondary battery is disposed so as to cover the entire surface of the opposite side.

3. 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.

4. The electronic device according to claim 1 , wherein a plurality of the secondary batteries are arranged on the opposite surface.

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