JPH022098A - Solar cell for ic card - Google Patents

Abstract

PURPOSE:To adapt a solar cell to a thin and small IC card by dispensing with a secondary cell and to prevent erroneous operation due to the variation in the quantity of light by using a flexible thin stainless steel substrate to unify a lamination type solar cell and a condenser. CONSTITUTION:A dielectric layer 2 is formed on a flexible thin stainless steel substrate 1 and an electrode 3 is vapor-deposited thereon to form a condenser having capacity absorbing a surface current due to the variation in the receiving quantity of light. The solar cell 3 integrally formed on the condenser is formed by laminating two or more photoelectric energy converting layers 4a-4c to the electrode 3 and further applying a transparent conductive film 5 and a protective resist 6 thereon in succession. This lamination type solar cell 4 can supply operable power containing the writing operation to the EEPROM of an IC card and, since the condenser 3 stores solar cell energy, a surge current due to the variation in the receiving quantity of light is absorbed and, when this solar cell is used as the power supply of the IC card, the erroneous operation of an IC can be prevented.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a solar cell for an IC card, and particularly to a solar cell for an IC card that is formed integrally with a capacitor to prevent malfunctions due to instantaneous changes in the amount of light. It is related to batteries.

[Conventional technology]

Conventionally, one side of the card is equipped with a keyboard for inputting data, a liquid crystal display for displaying data, and a solar cell for power supply. The card is equipped with external connection terminals for receiving power and sending and receiving signals, as well as embossments representing identification codes, etc. The card also contains a secondary battery for storage connected to the solar cell, a central processing unit (CPU), and a program. ROM to store, RAM to store data during CPU operation
, an IC card with a built-in electrically rewritable EEPROM, a display drive circuit, etc. has been proposed (Japanese Patent Application Laid-open No. 61
-5389 Publication).

Such an IC card temporarily stores energy obtained from a solar cell in a secondary battery, and is driven by power supplied from the secondary battery.

[Problem to be solved by the invention]

By the way, when such conventional IC cards are directly driven by solar cells, the supplied current fluctuates and becomes unstable depending on the amount of light received, so in order to stably supply energy, two
Next battery is required.

As a result, the circuit configuration becomes complicated and large, leading to an increase in cost. In response, proposals have been made in the fields of calculators and watches that do not use secondary batteries, but rather integrate solar cells and large-capacity capacitors, and store energy in the capacitors to drive the devices (for example, JP-A-Sho). 61
-70769, JP 62-106671, JP 6:2-92380).

However, in conventional capacitors integrated with solar cells, the solar cells are mainly integrated with a single layer structure, and the substrate is a transparent glass substrate, so the overall thickness is This makes it difficult to apply it to an IC card because it becomes large and has a large size.

The present invention is intended to solve the above problems, and uses a stacked solar cell as a solar cell and a flexible stainless steel substrate as a substrate to create an IC that can be applied to a single and small IC card. The purpose of this invention is to provide a solar cell for cards.

[Means to solve the problem]

To this end, the present invention provides a solar cell for an IC card in which a solar cell and a capacitor are laminated on a stainless steel substrate, and the solar cell has a laminated structure consisting of a plurality of photoelectric energy conversion layers. A solar cell is formed on one surface, a capacitor is formed on the other surface, and the solar cell has a laminated structure consisting of a plurality of photoelectric energy conversion layers.

[Function] The present invention uses a flexible and thin stainless steel substrate as a substrate, which also serves as an electrode, forms a dielectric layer on this to form a capacitor, and furthermore, a solar panel is formed on the substrate or on the opposite side of the stainless steel substrate. By forming a battery, a solar cell and a capacitor are integrated, making it possible to eliminate the need for a secondary battery and make it applicable to thin and small IC cards.The integrated capacitor absorbs surge currents caused by fluctuations in light intensity and prevents malfunctions. can do.

[Example] Examples will be described below with reference to the drawings.

FIG. 1 is a diagram showing a cross section of an embodiment of the solar cell of the present invention, in which 1 is a stainless steel substrate, 2 is a dielectric layer, 3 is an electrode,
4 is a photoelectric energy conversion layer consisting of 4a to 4b, 5 is a transparent conductive film (electrode), 6 is a protective layer, and 7 is an insulating material.

A stainless steel substrate 1 is a flexible thin conductive substrate, on which a dielectric layer 2 is formed by sputtering, and an electrode 3 is deposited thereon to form a capacitor. The capacitor must have a capacity to absorb surge current caused by fluctuations in the amount of light received, specifically 1pF to 0.5μ.
It is assumed that the capacity is F. Additionally, a solar cell is integrally formed on the capacitor. In this solar cell, a plurality of photoelectric energy conversion layers 48 to 4C are laminated on the electrode 3, and indium oxide (IT
A transparent conductive film 5 made of O) or the like and a protective resist 6 are respectively deposited thereon.

Each photoelectric energy conversion JiI4a to 4C is converted into P-I-N type or N-1 type by plasma CVD method or the like.
- made of P-type amorphous silicon, each layer of which is electrically connected in series to form an electrode 3 and a transparent electrode 5;
It has a multilayer-series connection structure in which electrical energy is output from the two. In addition, each photoelectric energy changing tA layer 4a to 4
C has different light absorption wavelength characteristics, and for example, from the lower layer to the upper layer, it has the ability to more efficiently convert light with a shorter wavelength into electrical energy, and each layer converts the irradiated light into electrical energy more efficiently. . This is because the absorption coefficient of light is large at short wavelengths and becomes small at long wavelengths, so by gradually increasing the thickness of each photoelectric conversion layer from the light incident side, the amount of light absorbed by each layer can be increased. As a result, the current generated in each layer is made equal (current matching).

The solar cell according to the present invention is used as a power source for semiconductor devices such as IC cards, which are often used indoors. Generally, the wavelength from a fluorescent lamp is about 3,500 to 7,500 nm, and in this case, the thickness of the two layers of the first, second, and third photoelectric energy conversion elements is 50 to 100 nm, and the thickness of the n-layer is 50 to 100 nm. n
rm is 90 to XIO, and the film thickness of each layer is 3200 to 4000 for the first photoelectric energy conversion layer 4c, 1000 to 1200 for the second photoelectric energy conversion IA layer 4b, and 1000 to 1200 for the third photoelectric energy conversion layer 4b.
The photoelectric energy conversion layer 4a is said to have 420 to 520 people.

In this embodiment, the lower electrode 3 of the solar cell has a thickness of 0.0
It is preferable to use a flexible stainless steel substrate with a thickness of 5 to 0.2 mm, and the upper transparent electrode 5 is made of a transparent conductive film IT.
It is preferable that O is formed to have a thickness of 600 to 1000. Furthermore, it is preferable to coat the transparent mold (5) with a protective layer (
A barrier film 6 is formed. The protective layer needs to be a light-transmissive film, and can be formed of, for example, epoxy resin or fluororesin on the transparent electrode 5 to a thickness of 5 to 30 μm, usually about 10 μm.

In the present invention, the two layers of the first, second and third photoelectric energy conversion layers are preferably formed of a-3i:C:H or a-3i:II, and the n layer is preferably formed of μc-3i:II. preferable. In addition, the i-layer uses an a-3i:II semiconductor,
By changing the i-layer into a davyoid, the light absorption efficiency can be improved and the generated current can be increased. Furthermore, the a-3i
:H's single-layer bandgap can be easily controlled to be narrow by controlling the film-forming conditions during the film-forming process by the plasma CVD method, which is suitable from the viewpoint of manufacturing.

In other words, the reason why the bandgap of the i-layer changes to a waveguide is due to the H2/S of the source gas under the film forming conditions.
This can be achieved very suitably by continuously changing the iH4 ratio, substrate temperature, discharge power, etc. By continuously changing the film-forming conditions in this way, in this example, the voltage from the first photoelectric energy conversion layer 4c on the lower mold ( ) side to the third photoelectric conversion element 4a on the transparent electrode side is 1.7 eV~ In other words, from the third photoelectric energy conversion layer on the transparent electrode side to the first
Good results were obtained by forming the film in such a way that it gradually decreased into the photoelectric energy conversion layer.

Further, the transparent conductive film 5 is formed to extend so as to short-circuit it with the stainless steel substrate l, and in this case, an insulating material 7 is provided between the capacitor portion and the conductive film to prevent a short-circuit between the electrodes of the capacitor. I try not to let it happen. In this way, the capacitor is connected in parallel to the solar cell, resulting in an equivalent circuit as shown in FIG.

This type of stacked solar cell is used as an IC card EIEPR.
It is possible to supply power for operation, including writing operations to the OM, and since the capacitor is integrally formed and the solar cell energy is temporarily stored in the capacitor, surge current due to fluctuations in the amount of light received is absorbed, and therefore the IC
If used as a card power supply, IC malfunction can be prevented.

FIG. 3 is a diagram showing another embodiment of the solar cell of the present invention. In this embodiment, the solar cell and the capacitor are formed on the opposite side to the stainless steel substrate, and the stainless steel substrate is the solar cell. In addition to serving as the substrate for the capacitor and the capacitor, it also serves as a box for one of the capacitors.In this case, the solar cell and the capacitor are connected in parallel using a transparent conductive film, and the conductive film is used to prevent short-circuiting between the two electrodes of the capacitor. Insulating material 7
has been established.

By adopting the configuration shown in Figure 3, there is no need to form additional solar cells on top of the capacitor, so the electrode surface of the capacitor will not be damaged or shadowed during the formation process. , uniformity of performance can be maintained.

Next, an example in which the solar cell of the present invention is applied to an RC card will be explained with reference to FIG. 4.

FIG. 4 is a diagram showing an IC card using the solar cell of the present invention.

As shown in FIG. 4, the solar battery-equipped IC card has a card 2I made of plastic or the like, and one side of the card 2I has a key input section 22 for data input consisting of a keyboard, etc., and an LCD, etc. A display device 23 for displaying data and a solar cell 24 for supplying power are provided. The other side of the card 21 has a contact or non-contact external connection terminal 25 for receiving power and transmitting signals from an external terminal device, etc., and embossed or printed characters representing an identification code, etc. etc. are attached. Also, inside the card 21 is an IC for operating this card.
26 are provided.

〔Effect of the invention〕

As described above, according to the present invention, a laminated type thick 1L J3T is manufactured using a flexible and stainless steel substrate as a substrate.
By integrally forming an i-cell and a capacitor, a secondary battery is not required and the device can be applied to a thin and small IC card.The integrally formed capacitor absorbs surge current due to fluctuations in light intensity and prevents malfunctions.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a cross section of an embodiment of the solar cell of the present invention,
FIG. 2 is a diagram showing an equivalent circuit, FIG. 3 is a diagram showing another embodiment of the solar cell of the present invention, and FIG. 4 is a diagram showing an IC card using the solar cell of the present invention. 1... Stainless steel substrate, 2... Dielectric layer, 3...
Electrode, 4... Photoelectric energy conversion layer, 5... Transparent conductive layer (electrode), 6... Protective layer, 7... Insulating material. Applicant Toa Fuel Co., Ltd. Agent Patent Attorney Masanobu Hirukawa (4 others) Figure 1 Figure 2 Figure 3

Claims (3)

[Claims] (1) A solar cell for an IC card, characterized in that a solar cell and a capacitor are laminated on a stainless steel substrate, and the solar cell has a laminated structure consisting of a plurality of photoelectric energy conversion layers. (2) I characterized in that a solar cell is formed on one side of a stainless steel substrate and a capacitor is formed on the other side, and the solar cell has a laminated structure consisting of a plurality of photoelectric energy conversion layers.
Solar battery for C card. (3) The solar cell for an IC card according to claim 1 or 2, wherein the capacitor has a capacity capable of absorbing surge current due to fluctuations in the amount of received light.