JP2007139992A - Electrophoresis device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophoresis device whose component has a function of a dye-sensitized solar battery (photoelectric converting device). <P>SOLUTION: The electrophoresis device has first and second electrodes (11a, 11b) arranged opposite to each other, and a dispersion liquid (11c) which is present between the first and second electrodes and contains charged particles (11d) on which coloring matter sticks and a dispersion medium for dispersing the charged particles, and is characterized in that the dispersing medium of the dispersion liquid is an electrolyte and the coloring matter operates for photoelectric conversion. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an electrophoretic device using an electrophoretic mechanism that also functions as a photovoltaic cell, and an electronic apparatus using the electrophoretic device.

Recently, a dye-sensitized solar cell that can be manufactured at a lower cost than a silicon-based solar cell has attracted attention. A dye-sensitized solar cell is a photoelectric conversion device that generates light circulation using light between a pair of electrodes. It has a configuration in which titania particles formed by firing on an anode made of ITO and a dye attached on the titania particles are provided, and an electrolyte is filled between the dye and the cathode. When this dye has a photoelectric conversion function and absorbs light, the excited electrons move sequentially to the lowest empty orbit (LUMO) of the dye, LUMO of titanium oxide, and LUMO of ITO. From the cathode, electrons move through the electrolyte layer to the dye and are replenished to the holes from which electrons have been excited. Patent Document 1 discloses an example of a dye-sensitized solar cell and a method for manufacturing the same.
In addition, the electrophoresis apparatus encloses a dispersion liquid in which electrophoretic particles are dispersed in a dispersion medium between a pair of transparent electrode substrates, at least one of which is transparent, and changes the distribution of the electrophoretic particles according to the voltage applied between the electrodes As a result, a change is made to the optical reflection characteristics to perform a required display operation. For example, Patent Document 2 discloses an example of such an electrophoresis apparatus.
Japanese Patent Laid-Open No. 1-220380 Japanese Patent No. 2551783

  An electrophoretic device can be formed in a sheet shape, and is being developed as a display unit for electronic paper, a clock, a calculator, a PDA, and the like. A power source is required to operate the electrophoretic device. However, if a solar cell can be used as a power source, it is energy-saving and convenient for carrying.

  However, when a solar cell is incorporated in a part of the electrophoresis apparatus, the displayable area is reduced accordingly, and the manufacturing process becomes complicated. Moreover, handling is complicated if a solar cell is arranged and connected outside the electrophoresis apparatus. In addition, when the solar cell is formed as a light-transmitting sheet so as to overlap the display surface, the display becomes difficult to see due to light absorption.

  Therefore, an object of the present invention is to provide an electrophoresis device in which the constituent elements of the electrophoresis device have the function of a solar cell (photoelectric conversion device).

  In order to achieve the above object, an electrophoretic device of the present invention comprises first and second electrodes arranged opposite to each other, charged particles that exist between the first and second electrodes and contain a dye, and And a dispersion liquid containing a dispersion medium for dispersing charged particles. The dispersion medium of the dispersion liquid is an electrolyte, and the dye has a photoelectric conversion function.

  According to this configuration, the electrophoretic device can function as a dye-sensitized solar cell, and charges generated by the photoelectric conversion action of the dye can be taken out to the two electrodes via the electrolyte. When the electrophoresis apparatus of the present application is driven, the charged particles move to one electrode. When this is sufficiently close to the vicinity of the electrode, the photoelectric conversion function of the dye adhering to the surface of the charged particles works, and electrons move from the dye to one electrode via the titania particles. Thereby, electric power is produced. Note that when the charged particles are far from the electrode, light does not reach the dye, and the dye does not exhibit a photoelectric conversion function.

  Preferably, a control unit for connecting a secondary battery or a capacitor between the first and second electrodes is further included. Accordingly, the secondary battery or the capacitor can be charged with electricity obtained from the electrophoresis panel.

  Preferably, the charged particle includes a central particle serving as a nucleus, a dye attached to the central particle, and a reverse electron transfer prevention layer existing between the central particle and the dye. Thereby, charged particles that can function as a dye-sensitized solar cell can be obtained.

  Preferably, the charged particles include a central particle serving as a nucleus, a surface active material bonded to the center particle, the dye bonded to the surface active material, and a reverse existing between the center particle and the dye. An electron migration preventing layer. This expands the types of dyes that can be used.

  In general electrophoretic devices, color particles such as acrylic are used or color filters are formed for color display. However, in the present application, color display can be performed with a dye having charged particles adsorbed on the surface. .

Preferably, the central particle is a titania particle, and the titania particle and the surface active material are molecularly bonded. Although the titania particles are used as charged particles of a normal electrophoresis apparatus, the surface is covered with silicon oxide SiO ₂ . Therefore, when used as a dye-sensitized solar cell, the electric resistance between the dye and titania particles is large, and the power generation efficiency is lowered. On the other hand, the power generation efficiency can be increased by the above configuration.

  Preferably, the central particle has an OH group on the surface. The charged particles are negatively charged.

  Preferably, the dispersion liquid migrates the charged particles and functions as an electrolyte of a dye-sensitized solar cell. A dispersion liquid of an ordinary electrophoretic display device is one in which charged particles migrate into a low-polarity dispersion medium such as benzene. Since the dispersion of the present application also functions as an electrolyte for solar cells, it has a relatively high polarity. However, charged particles migrate.

For example, 0.1 mol of lithium iodide (LiI), 0.05 mol of iodine (I ₂ ), 0.5 mol of tetrapropylammonium iodide ((C ₃ H ₇ ) ₄ NI), 0.05 mol of 4-t -Butylpyridine ((CH ₃ ) ₃ · C ₅ H ₄ N dissolved in acetonitrile CH ₃ CN and 2-methoxyethanol CH ₃ OCH ₂ CH ₂ OH (volume ratio 1: 1) can be used. Thus, the charged particles can achieve both the function as the display particles of the electrophoretic device and the function as the solar cell.

  In addition, the electronic apparatus of the present invention uses the above-described electrophoresis apparatus as its display unit. There is an advantage that it is easy to obtain energy-saving equipment and downsized devices.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  In the present invention, the electrophoretic display device functions as a dye-sensitized solar cell. For this reason, a charged particle is formed by adhering a dye having a photoelectric conversion action to particles (center particle) capable of moving charges. The charged particles are moved between the two electrodes in accordance with the applied voltage, and the dispersion medium is made of a dispersion liquid (electrophoresis of particles) so that the charge generated by the charged particle dye circulates between the electrodes. Selected) so that it can function as a battery electrolyte (conducts electricity).

  1 to 4 are explanatory views for explaining an electrophoresis apparatus and its operation according to the present invention.

  First, the electrophoresis apparatus 10 is roughly configured by an EPD panel unit 11, a first drive unit 12, and a second drive unit 13.

  The EPD panel unit 11 includes a substrate 11a as a first substrate, a substrate 11b as a second electrode, a dispersion 11c sealed between the two substrates, and charged particles 11d arranged in the dispersion. . Examples of the substrate 11a include a transparent ITO (indium tin oxide) electrode formed on a transparent substrate such as transparent PEN (polyethylene naphthalate) or a transparent glass substrate, A transparent ITO (indium tin oxide) electrode is formed on a PET (polyethylene terephthalate) substrate. The substrate 11b is configured, for example, by forming a platinum electrode on a transparent PET (polyethylene terephthalate) substrate.

The dispersion liquid 11c causes the charged particles 11d to function as a dye-sensitized solar cell and electrophoretic particles, and acts as an electrolyte solution and a dispersion medium. In the present application, as such a dispersion, for example, 0.1 mol of lithium iodide (LiI), 0.05 mol of iodine (I ₂ ), 0.5 mol of tetrapropylammonium iodide ((C ₃ H ₇ ) ₄ NI), 0.05 mol of 4-tert-butylpyridine ((CH ₃ ) ₃ .C ₅ H ₄ N into acetonitrile CH ₃ CN and 2-methoxyethanol CH ₃ OCH ₂ CH ₂ OH (volume ratio 1: 1). Not limited to this, a system using an ionic liquid, that is, 1-Ethyl-3-methylimidazolium bis (trifuluorosulfonyl) amide (EMIm TFSI) and LiI (about 0.1 M / l) can be used. What dissolved iodine (about 0.15M / l) may be used.

For example, as shown in FIG. 6, the charged particle 11 d has a structure in which the substance B, which is an organic semiconductor, is adsorbed on the substance A, and the substance C is polymerized between the substances A and B. . Here, the substance A is a nucleus of the charged particle 11d, and is, for example, white titanium oxide (TiO ₂ ), black titanium black (TiNO), or zinc oxide (ZnO). Titanium oxide and titanium black tend to be negatively charged because OH groups exist on the particle surface. Particle B is a pigment. This dye is characterized by having a polymerized group.

  The substance C is a reverse electron transfer prevention layer that prevents the electrons transferred from the substance B to the substance A from causing reverse electron transfer. This reverse electron transfer prevention layer is a polymerized film serving as a physical barrier provided between a dye serving as an electron donor and titanium oxide serving as an acceptor. Usually, in dye-sensitized solar cells, electrons move from dye to titanium oxide and from titanium oxide to the anode, but do not move from titanium oxide to the anode, but return to the dye. It was a factor that lowered efficiency. This reverse electron transfer prevention layer can reduce a decrease in power generation efficiency.

  Titanium oxide used as the charged particles in the electrophoresis apparatus is often coated with a silicon oxide film in order to suppress the photocatalytic action of titanium oxide and extend its life. In this embodiment, titanium oxide is used. A silicon oxide film is not formed in order to make the particles function as an electrode of a solar cell. That is, the titanium oxide and the surface active material layer are molecularly bonded.

Examples of the dye include a ruthenium complex such as RuL ₂ (SCN) ₂ , RuL ₂ Cl ₂ , RuL ₂ CN ₂ , Ruthenium 535-bisTBA (manufactured by Solaronics), [RuL ₂ (NCS ₂ )] ₂ H ₂ O, Metal complex dyes such as iron complex, osmium complex, copper complex, platinum complex, cyan dye, xanthene dye, azo dye, hibiscus dye, blackberry dye, raspberry dye, pomegranate juice dye, chlorophyll dye, etc. One or more of these can be used in combination.

  Among these dyes, it is preferable to use a metal complex. The metal complex has a relatively wide wavelength range of light that can be absorbed and has excellent photosensitization characteristics.

  Further, as the dye, it is more preferable to use a ruthenium complex or an iron complex among metal complexes. These complexes have particularly excellent photosensitization properties and relatively high chemical stability.

  The first drive unit 12 includes switches SW1 to SW4 and a secondary battery 12a. The second drive unit 13 includes switches SW5 to SW8 and a secondary battery 13a. The secondary batteries 12A and 13a may be capacitors (capacitors). The operations of the switches SW1 to SW8 are controlled by the control unit 20. The control unit 20 is configured by, for example, a logic gate and a control CPU.

  Next, the operation of the electrophoresis apparatus 10 will be described. First, as shown in FIG. 1, when the charged particle 11d is at an intermediate position between the two electrode substrates 11a and 11b, an ON (display) command signal is supplied to the control unit 20 from the outside. The switches SW1 and SW4 are closed. Other switches SW are open. Thereby, the voltage of the secondary battery 12a is applied between both substrates. The charged particles 11d are negatively charged, move toward the electrode substrate 11a to which the positive electrode of the secondary battery is connected (upward), and adhere to the electrode substrate 11a.

  Next, as shown in FIG. 2, the charged particles 11 d adhere to the electrode substrate 11 a to display a pixel or mosaic element. Thereafter, the control unit 20 closes the switches SW2 and SW3 and opens the others as illustrated.

  When the charged particles 11d attached to the electrode substrate 11a are irradiated with light such as sunlight, the dye (molecules) is excited by the energy. The dye generates excitons (excitons) that are pairs of electrons and holes. The holes flow through the dispersion medium (dispersion liquid) 11c, which is an electrolyte solution, the electrode substrate 11b, and the switch SW3 to the positive electrode of the secondary battery 12a. Electrons flow from the particle A to the negative electrode of the secondary battery 12a through the electrode substrate 11a and the switch SW2. Thereby, the secondary battery 12a is charged by the dye-sensitized solar cell.

  Next, an off (non-display) command signal is supplied to the control unit 20. As shown in FIG. 3, the control unit 20 closes the switches SW5 and SW8 and opens the others. As a result, a reverse bias voltage is applied between the electrode substrates by the secondary battery 13a. Since the charged particles 11d are originally negatively charged, they move away from the electrode substrate 11a and move toward the electrode substrate 11b. The power generation function of the charged particles 11d is stopped by the separation of the charged particles 11d from the electrode substrate 11a.

  As shown in FIG. 4, when the charged particle 11d moves and contacts the electrode substrate 11b, the control unit 20 closes the switches SW6 and SW7 and opens the others.

  Similarly, when the charged particles 11d adhering to the electrode substrate 11b are irradiated with light such as sunlight, the dye (molecules) is excited by the energy. The dye generates excitons (excitons) that are pairs of electrons and holes. Exciton is divided into electrons and holes at the interface of substance A, which is a nucleus. The holes pass from the substance A through the substance C, flow through the dispersion medium (dispersion) 11c, which is an electrolyte solution, the electrode substrate 11a, and the switch SW6, and flow to the positive electrode of the secondary battery 13a. Electrons flow from the substance A through the electrode substrate 11b and the switch SW7 to the negative electrode of the secondary battery 13a. Thereby, the secondary battery 13a is charged by the charged particles 11d.

  FIG. 5 is an explanatory diagram for explaining the display state in each position state of the charged particles 11d of FIGS. 1 to 4 described above. When the charged particles 11d are present on the upper electrode 11a (FIG. 2), a clear image or segment is displayed.

  Thus, when the charged particles 11d are present on the electrode substrate, the secondary battery is charged by the power generation function of the charged particles 11d. The display position of the charged particles 11d is controlled by the energy stored in the secondary battery. In the above-described embodiment, one secondary battery is charged when the charged particles 11d are present on one electrode, and the other secondary battery is charged when the charged particles 11d are present on the other electrode. However, it is not limited to this.

  For example, by appropriately configuring the switch circuit, the direction of current flow and the selection of the secondary battery in the drive units 12 and 13 can be switched appropriately when the charged particles 11d are always present on one electrode. Can be set. Thereby, two batteries can be charged simultaneously or alternately.

  In addition, it is possible to make one secondary battery by appropriately setting each current direction of the driving unit when the charged particles 11d are driven and when the secondary battery is charged by the switch circuit.

  7 and 8 show other structural examples of the charged particles. In each figure, the same particle name is given to the part corresponding to FIG.

  FIG. 7 shows an example of the second particle structure of the charged particle 11d.

  As described above, for example, the substance B which is an organic semiconductor (pigment) is adsorbed on the substance A which is the nucleus of the charged particle 11d. The substance C is polymerized between the substances A and B. Substance B is a pigment.

  In this example, substance D and substance E are further included. The substance D is an anionic (anionic) or cationic (cationic) surface active material, and the substance E is a cationic or anionic polymerizable surface active material.

  By including such a surface active material, there is an advantage that various dyes are easily adsorbed to the substance A. Thereby, there is an advantage that the selection range of the color (coloring material) is expanded.

  FIG. 8 shows an example of the third particle structure of the charged particle 11d. Substance A is encapsulated with a polymer. As the polymer, for example, polypinol, polyacetylene and the like can be used.

  As in this example, the charged particles 11d can be physically and chemically stabilized by encapsulating the charged particles 11d.

(Other examples)
FIG. 9 shows an example in which the electrophoresis apparatus 10 of the present invention is applied to the display unit 102 of a calculator 100 which is an electronic device. Since the electrophoretic device 10 itself has a power generation function, a solar cell panel that has been conventionally arranged is not necessary, and the size can be further reduced. If the power generation capability of the electrophoresis apparatus 10 is increased, it can also be used as a power source for the calculator 100.

  In addition, the electrophoretic device 10 of the present invention is suitable for use as a display device for electronic devices such as watches, electronic calendars, electronic books, electronic advertising devices, PDAs (personal digital assistants), personal computers and mobile phones.

  The electrophoretic device of the present invention is not limited to the above-described embodiment, and it goes without saying that various changes can be made without departing from the scope of the present invention.

It is explanatory drawing explaining the operation | movement of the 1st step of the electrophoresis apparatus of this invention. It is explanatory drawing explaining operation | movement of the 2nd step of the electrophoresis apparatus of this invention. It is explanatory drawing explaining the operation | movement of the 3rd step of the electrophoresis apparatus of this invention. It is explanatory drawing explaining the operation | movement of the 4th step of the electrophoresis apparatus of this invention. It is explanatory drawing explaining the display state in each step. It is explanatory drawing explaining the 1st example of the particle | grains of the solar cell used for this invention. It is explanatory drawing explaining the 2nd example of the particle | grains of the solar cell used for this invention. It is explanatory drawing explaining the 3rd example of the particle | grains of the solar cell used for this invention. It is explanatory drawing explaining the example (calculator) of the electronic device using the electrophoresis apparatus of this invention.

Explanation of symbols

10 Electrophoresis device, 11 EPD panel, 12, 13 Drive unit 20 Control unit

Claims (8)

First and second electrodes disposed opposite each other;
A dispersion liquid that is present between the first and second electrodes and includes a charged particle including a pigment and a dispersion medium in which the charged particle is dispersed;
The dispersion medium of the dispersion is an electrolyte,
The dye has a photoelectric conversion action,
An electrophoresis apparatus characterized by that.   The electrophoretic device according to claim 1, further comprising a control unit that connects a secondary battery or a capacitor between the first and second electrodes. The charged particles include core particles serving as nuclei,
A dye attached to the central particle;
A reverse electron transfer prevention layer present between the central particle and the dye;
The electrophoresis apparatus according to claim 1, comprising: The charged particles include core particles serving as nuclei,
A surface active material bonded to the central particle;
The dye bound to the surface active material;
A reverse electron transfer prevention layer present between the central particle and the dye;
The electrophoresis apparatus according to claim 1, comprising:   The electrophoresis apparatus according to claim 4, wherein the central particle is a titania particle, and the titania particle and the surface active material are molecularly bonded.   The electrophoresis apparatus according to claim 3, wherein the central particle has an OH group on a surface.   The electrophoretic device according to claim 1, wherein the dispersion liquid migrates the charged particles and functions as an electrolyte of a dye-sensitized solar cell. An electronic apparatus using the electrophoretic device according to claim 1 for a display.

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