JP5625270B2 - Organic diodes, organic rectifiers and non-contact information media - Google Patents

Description

  The present invention relates to an organic diode, in particular, a stacked organic diode, an organic rectifier using the organic diode, and a non-contact information medium.

  In general, a pn junction type using an inorganic semiconductor material such as silicon and a Schottky type using a p-type or n-type inorganic semiconductor material have been used as a diode. Recently, an organic semiconductor using an organic semiconductor as a semiconductor layer is used. Diode development is progressing. Organic diodes do not require a large-scale manufacturing apparatus such as inorganic diode manufacturing using an inorganic semiconductor material, and have the advantage of low manufacturing costs. Moreover, since process temperature is low, there exists an advantage that preparation to a film substrate etc. is easy. For this reason, the use of organic diodes is also being studied for non-contact information media such as RFID (Radio Frequency Identification) tags such as non-contact IC cards, identification tags, and product tags (Patent Document 1).

In a system using a non-contact type information medium, a reader / writer modulates a carrier wave of a predetermined frequency with a desired data string to generate a transmission signal, and sends the transmission signal to the non-contact type information medium. . On the other hand, a non-contact type information medium extracts data and power from a high frequency signal of 13.56 MHz from an antenna through a rectifier circuit composed of a diode and a capacitor, and at the time of transmission, the impedance of the circuit including the diode, the capacitor and the antenna is obtained. The data is transmitted to the reader / writer with changes.
Organic diodes are classified into an FET type in which a source electrode and a gate electrode are short-circuited using an FET (Field Effect Transistor) structure, and a laminated type in which an organic thin film is sandwiched between two electrodes. Since organic semiconductors have lower mobility than inorganic semiconductors, it is difficult to operate at a high frequency of 13.56 MHz in an FET type having a channel length of about 10 μm. On the other hand, the stacked organic diode has a carrier movement distance of about 0.1 μm, and even an organic material with low mobility can be operated at a high frequency of 13.56 MHZ (Non-patent Document 1).

Japanese translation of PCT publication No. 2004-508731

NATURE MATERIALS VOL. 4 597-600 pages (2005)

  However, on the other hand, when a stacked organic diode is operated at a high frequency of 13.56 MHz, the displacement potential derived from the parasitic capacitance of the element lowers the rectification characteristics, so that a current density sufficiently larger than the displacement current is required. It becomes. Generally, when a current with high current density is passed through an organic thin film, the performance of the organic diode deteriorates due to heat (current decrease over time increases or a short circuit occurs between the upper and lower electrodes that sandwich the organic thin film) As a result, the leakage current during reverse bias application increases and the rectification ratio decreases). This problem is remarkable when a substrate having poor thermal conductivity such as a resin film is used. In addition, since such a problem becomes prominent when the electrode area of the diode increases, in the conventional stacked organic diode, heat generation is suppressed and current density is increased by reducing the electrode area. However, as a result of reducing the electrode area, the device often has a high resistance.

On the other hand, in a non-contact type information medium having a driving element such as an IC or an organic light emitting diode, a voltage sufficient to operate these and do not adversely affect communication performance is required. However, the rectifier circuit has a problem that a sufficient voltage cannot be extracted from the high-frequency signal, particularly when the load resistance is small.
The present invention has been made in view of such circumstances, an organic diode whose resistance is reduced by suppressing heat generation, an organic rectifier capable of supplying a high DC voltage using the organic diode, and a reliable An object is to provide a high non-contact information medium.

In order to achieve such an object, an organic diode of the present invention comprises an organic semiconductor layer as a hole transport layer or an electron transport layer, and a pair of electrodes arranged so as to sandwich the organic semiconductor layer. In the organic diode for rectifying a high-frequency signal, at least one of the electrodes has a mesh shape having a plurality of circular openings having an opening diameter in a range of 10 μm to 1 mm in a range of 10 μm to 5 mm, and a width The electrode material in the range of 10 μm to 1 mm is formed in a honeycomb shape, and is configured to be a pattern electrode in any shape of a mesh shape having a plurality of hexagonal openings having an opening length in the range of 10 to 5 mm. .
As another aspect of the present invention, one of the electrodes is the pattern electrode, and the area occupation rate of the pattern electrode in the electrode formation region is in the range of 30 to 70%.
As another aspect of the present invention, the pair of electrodes are both the pattern electrodes, and the area occupation ratio of each pattern electrode in the electrode formation region is in the range of 20 to 80%.

  The organic rectifier of the present invention is configured to include at least one of the organic diodes described above.

  A non-contact information medium according to the present invention includes a resonance circuit for receiving and amplifying a high-frequency signal, a rectifier circuit for rectifying the high-frequency signal amplified by the resonance circuit, and a drive element based on a voltage obtained by the rectification circuit At least one of the organic diodes described above.

In the organic diode of the present invention, at least one of the pair of electrodes arranged so as to sandwich the organic semiconductor layer is either a mesh shape having a plurality of openings or a stripe shape having a plurality of stripe electrodes in parallel. Therefore, a device having a large area can be manufactured with a small current generation, a high current density, and a low resistance and excellent rectifying characteristics.
Moreover, the organic rectifier of the present invention including at least one organic diode of the present invention can extract a high DC voltage from a high-frequency signal.
Furthermore, the non-contact type information medium of the present invention having at least one organic diode of the present invention in the rectifier circuit can extract a high DC voltage from the received high-frequency signal and drive the driving element stably, and is reliable. Is high.

It is a schematic block diagram which shows one Embodiment of the organic diode of this invention. It is a top view which shows the example of the mesh-shaped pattern electrode which comprises the organic diode of this invention. It is a top view which shows the other example of the mesh-shaped pattern electrode which comprises the organic diode of this invention. It is a top view which shows the other example of the mesh-shaped pattern electrode which comprises the organic diode of this invention. It is a top view which shows the example of the stripe-shaped pattern electrode which comprises the organic diode of this invention. It is a half-wave rectifier circuit diagram which shows one Embodiment of the organic rectifier of this invention. It is a double wave rectifier circuit diagram which shows other embodiment of the organic rectifier of this invention. It is a bridge rectifier circuit diagram which shows other embodiment of the organic rectifier of this invention. It is a half-wave voltage doubler rectifier circuit diagram which shows other embodiment of the organic rectifier of this invention. It is a double wave voltage doubler rectifier circuit diagram which shows other embodiment of the organic rectifier of this invention. It is a circuit block diagram which shows one Embodiment of the non-contact-type information medium of this invention. It is the rectifier circuit diagram incorporating the organic diode produced in the Example.

Next, embodiments of the present invention will be described with reference to the drawings.
[Organic diode]
FIG. 1 is a schematic configuration diagram showing an embodiment of an organic diode of the present invention. In FIG. 1, the organic diode 1 includes an organic semiconductor layer 2 and a pair of electrodes 3 and 4 disposed so as to sandwich the organic semiconductor layer 2. In the present invention, at least one of the electrodes 3 and 4 is a pattern electrode having any one of a mesh shape having a plurality of openings and a stripe shape in which a plurality of stripe electrodes are arranged in parallel.

  The organic semiconductor layer 2 constituting the organic diode 1 is a hole transport layer or an electron transport layer. As the organic compound having a hole transporting ability, conventionally known compounds can be used, for example, phthalocyanine, naphthalocyanine, porphyrin, oxadiazole, triphenylamine, triazole, imidazole, imidazolone, pyrazoline, tetrahydroimidazole, hydrazone. , Stilbene, pentacene, polythiophene, butadiene and the like, and derivatives thereof. Moreover, as an organic compound having an electron transporting ability, a conventionally known compound can be used, for example, fullerene, anthraquinodimethane, fluorenylidenementa, tetracyanoethylene, fluorenone, diphenoquinone oxadiazole, Anthrone, thiopyran dioxide, diphenoquinone, benzoquinone, malononitrile, dinitrobenzene, nitroanthraquinone, maleic anhydride, perylenetetracarboxylic acid, etc., and derivatives thereof can be mentioned.

One of the electrodes 3 and 4 constituting the organic diode 1 forms a large carrier injection barrier with the organic semiconductor layer 2 (hereinafter referred to as a Schottky contact for convenience), and the other electrode is connected to the organic semiconductor layer 2. It forms a small carrier injection barrier (hereinafter referred to as ohmic contact for convenience).
When the organic semiconductor layer 2 is a hole transport layer, the electrode in ohmic contact with the organic semiconductor layer 2 is made of a material having a work function similar to or larger than the HOMO of the hole transport layer, for example, gold, platinum, palladium, nickel, Electrode material comprising any one of indium tin oxide (ITO), iridium zinc oxide, zinc oxide, polyaniline, poly (3,4) ethylenedioxythiophene / polystyrene sulfonate (PEDOT / PSS), or a combination thereof Can be formed. In addition, the electrode making Schottky contact with the organic semiconductor layer 2 is made of a material having a work function smaller than 0.5 eV or more than the HOMO of the hole transport layer, for example, aluminum, silver, tin, lead, alkaline earth metal, Ca-Al , Mg—Ag, Li—Al and other metal alloys, nano silver, etc., or a combination thereof.

  On the other hand, when the organic semiconductor layer 2 is an electron transport layer, the electrode making Schottky contact with the organic semiconductor layer 2 is made of a material having a work function larger than 0.5 eV or more than the LUMO of the electron transport layer, for example, gold, platinum, One of palladium, nickel, indium, indium tin oxide (ITO), iridium zinc oxide, zinc oxide, polyaniline, poly (3,4) ethylenedioxythiophene / polystyrene sulfonate (PEDOT / PSS), or these It can be formed of an electrode material made of a combination of the above. In addition, the electrode that is in ohmic contact with the organic semiconductor layer 2 is made of a material having a work function comparable to or smaller than the LUMO of the electron transport layer, such as aluminum, silver, tin, lead, alkaline earth metal, Ca—Al, Mg. It can be formed of an electrode material composed of any one of metal alloys such as -Ag and Li-Al, or a combination thereof.

In addition, as described above, the electrodes 3 and 4 constituting the organic diode 1 have at least one of a mesh shape having a plurality of openings and a stripe shape pattern having a plurality of stripe electrodes in parallel. Electrode. 2 to 4 are plan views illustrating examples of mesh-shaped pattern electrodes. In the illustrated example, the electrode 4 is a pattern electrode. However, the electrode 3 may be a pattern electrode. Of course.
The pattern electrode 4 shown in FIG. 2 has an electrode material formed in a lattice shape and has a plurality of rectangular openings 5. In this case, the width W of the grid-shaped electrode can be set in a range of about 10 μm to 1 mm, and the opening length L of the opening 5 can be set in a range of about 10 μm to 5 mm.
The pattern electrode 4 shown in FIG. 3 has a plurality of circular openings 5. In this case, the opening diameter D of the circular openings 5 can be set in the range of 10 μm to 1 mm, and the pitch P of the adjacent openings 5 can be set in the range of about 10 μm to 5 mm.

The pattern electrode 4 shown in FIG. 4 has an electrode material formed in a honeycomb shape and has a plurality of hexagonal openings 5. In this case, the width W of the honeycomb-shaped electrode can be set in the range of about 10 μm to 1 mm, and the opening length L of the opening 5 can be set in the range of about 10 μm to 5 mm.
FIG. 5 is a plan view showing an example of a stripe-shaped pattern electrode. In the example shown in FIG. 5, the electrode 4 is a pattern electrode in which a plurality of stripe-shaped electrodes 4a are arranged in parallel. In this case, the width W of the electrode 4a can be set in the range of about 10 μm to 1 mm and the pitch P in the range of about 10 μm to 5 mm. 5 shows an example in which the electrode 4 is a stripe-shaped pattern electrode, the electrode 3 may be a stripe-shaped pattern electrode.

The area occupancy of the electrode (pattern electrode) 4 as described above in the electrode formation region (the region indicated by the alternate long and short dash line in FIGS. 2 to 5) is in the range of 30 to 70%, preferably 40 to 60%. An area occupancy of less than 30% is not preferable because the resistance of the electrode increases and the device characteristics deteriorate. Further, if the area occupation ratio of the electrodes exceeds 70%, the influence of heat generation cannot be avoided, and the yield is lowered, which is not preferable.
In the present invention, both the electrodes 3 and 4 may be mesh-shaped or stripe-shaped pattern electrodes, one of the electrodes 3 and 4 is a mesh-shaped pattern electrode, and the other is a stripe-shaped pattern electrode. It may be. When both the electrodes 3 and 4 are stripe-shaped pattern electrodes, the stripe-shaped electrode constituting the electrode 3 and the stripe-shaped electrode constituting the electrode 4 intersect with each other via the organic semiconductor layer 2. Preferably it is. Thus, when the electrodes 3 and 4 are both pattern electrodes, the area occupancy of each electrode (pattern electrode) 3 and 4 occupying in the electrode formation region (the region indicated by the one-dot chain line in FIGS. 2 to 5) is 20 to 20. It is in the range of 80%, preferably 30 to 70%. If the area occupancy is less than 20%, the resistance of the electrode increases and the device characteristics deteriorate, which is not preferable. Further, if the area occupancy of the electrode exceeds 80%, the influence of heat generation cannot be avoided and the yield decreases, which is not preferable.

In the example of the pattern electrode described above, the openings 5 are uniformly distributed and the striped electrodes 4a are arranged at a uniform pitch. However, the present invention is not limited to this. For example, the distribution density of the openings 5 and the arrangement pitch of the striped electrodes 4a may be changed at the center and the peripheral portion in the electrode formation region.
The pattern electrode as described above can be formed by etching by providing a resist pattern on an electrode film formed by a coating method, a vacuum film forming method, or the like. Further, it may be formed by a vacuum film forming method through a mask, and further, it can be formed by an ink jet method, a screen printing method or the like.
The organic diode 1 of the present invention may be provided on a base material. In this case, the substrate is not particularly limited as long as it has sufficient mechanical strength and thermal strength to hold the organic diode 1, for example, an inorganic substrate such as glass, polyethylene terephthalate, polyethylene terephthalate, polycarbonate. Resin base materials such as polypropylene, polyethylene, polymethyl methacrylate, and polyimide can be used.
Such an organic diode of the present invention can increase the electrode area while suppressing heat generation per unit area, and thus can stably exhibit excellent rectification characteristics with low resistance.

[Organic rectifier]
The organic rectifier of the present invention comprises at least one organic diode of the present invention as a diode.
FIG. 6 is a half-wave rectifier circuit diagram showing an embodiment of the organic rectifier of the present invention. The organic rectifier 11 includes an organic diode 12 and a capacitor 16, and the organic diode 12 is the organic diode of the present invention. Note that the capacitor 16 is not necessary when the load itself has a sufficient capacitance component such as an organic light emitting diode.
FIG. 7 is a double-wave rectifier circuit diagram showing another embodiment of the organic rectifier of the present invention. The organic rectifier 21 includes organic diodes 22 and 23 and a capacitor 26, and the organic diodes 22 and 23 are the present invention. This is an organic diode.

FIG. 8 is a bridge rectifier circuit diagram showing another embodiment of the organic rectifier of the present invention. The organic rectifier 31 includes organic diodes 32, 33, 34, 35 and a capacitor 36, and the organic diodes 32, 33 are provided. , 34 and 35 are organic diodes of the present invention.
FIG. 9 is a half-wave voltage doubler rectifier circuit diagram showing another embodiment of the organic rectifier of the present invention. The organic rectifier 41 includes organic diodes 42 and 43 and capacitors 46 and 47, and the organic diode 42, 43 is an organic diode of the present invention.
Further, FIG. 10 is a double-wave voltage doubler rectifier circuit diagram showing another embodiment of the organic rectifier of the present invention. The organic rectifier 51 includes organic diodes 52 and 53 and capacitors 56 and 57, and the organic diode 52, 53 is an organic diode of the present invention.
Since the organic rectifier of the present invention uses the organic diode of the present invention, the current density can be increased to maintain stable rectification characteristics, and a high DC voltage can be extracted from the high-frequency signal.

[Non-contact information media]
The non-contact information medium of the present invention includes a resonance circuit for receiving and amplifying a high-frequency signal, a rectifier circuit for rectifying the high-frequency signal amplified by the resonance circuit, and a drive element by a voltage obtained by the rectification circuit And a rectifier circuit having at least one organic diode of the present invention.
FIG. 11 is a circuit configuration diagram showing an embodiment of the non-contact information medium of the present invention. In FIG. 11, the non-contact type information medium 71 includes a resonance circuit 72, a rectification circuit 73, and a load circuit 74.
The resonance circuit 72 is formed by connecting the antenna coil 81 and the capacitor 82 in parallel, and by adjusting the resonance frequency to the communication frequency (13.56 MHz) between the non-contact type information medium and the reader / writer, an electromotive force is generated by resonance. Can be greatly increased.

The rectifier circuit 73 includes the organic diode 83 and the capacitor 84 of the present invention, and rectifies the high frequency signal amplified by the resonance circuit 71. In the illustrated example, the rectifier circuit 72 is a half-wave rectifier circuit. However, the double-wave rectifier circuit, the bridge rectifier circuit, the half-wave voltage doubler rectifier circuit, and the double wave double voltage as mentioned in the description of the organic rectifier of the present invention described above. A rectifier circuit or the like may be used.
The load circuit 74 is a circuit that drives the drive element with the voltage obtained by the rectifier circuit 73. Examples of the driving element include an IC, an organic light emitting diode, and various sensors. In the illustrated example, the driving element is assumed to be represented by a load resistor 85.
Such a non-contact type information medium of the present invention is highly reliable because it can extract a high DC voltage from the received high-frequency signal and drive the drive element stably.
The embodiments described above are examples of the present invention, and the present invention is not limited to these embodiments.

Next, an Example is shown and this invention is demonstrated further in detail.
(Preparation of sample 1)
A polyethylene telenaphthalate film (manufactured by Teijin DuPont Co., Ltd.) having a thickness of 100 μm was prepared as a substrate.
A gold thin film having a thickness of 100 nm was formed on one surface of the substrate by vacuum deposition, and a positive photosensitive resist was applied on the gold thin film by spin coating to form a resist film having a thickness of 1 μm. . Next, exposure and development were performed through a predetermined mask to form a resist pattern in which five stripe patterns having a width of 30 μm were arranged in parallel at a pitch of 70 μm.
Next, using the above resist pattern as a mask, the gold thin film is etched using aqua regia, and a stripe-shaped electrode (length: 500 μm, width: 30 μm) is formed in an electrode formation area of 500 μm × 500 μm. ) Formed a pattern electrode in which five lines were arranged in parallel at a pitch of 70 μm. The area occupation ratio of the gold pattern electrode in the electrode formation region was 30%.

Next, a 2 wt% toluene solution of 3-hexylthiophene (P3HT) is applied by spin coating so as to cover the pattern electrode, and dried to dry the organic semiconductor layer (thickness). 120 nm). The organic semiconductor layer and the gold pattern electrode were in ohmic contact.
Next, an aluminum thin film having a thickness of 100 nm was formed on the organic semiconductor layer by mask vapor deposition by vacuum vapor deposition to form an aluminum electrode. This aluminum electrode was in Schottky contact with the organic semiconductor layer. Thereby, an organic diode (sample 1) was obtained.
As a rectifier circuit incorporating this organic diode, a rectifier circuit as shown in FIG. 12 was produced, and the DC voltage obtained by this rectifier circuit was measured and shown in Table 1 below. The rectifier circuit 100 shown in FIG. 12 includes an AC power supply 101 that supplies an AC voltage of 13.56 MHz at −7 / 7V, the organic diode 102, a capacitor 103 having a capacitance of 1 nF, and a load resistor 104 of 10 kΩ. It was supposed to be.

(Preparation of samples 2 and 3)
Organic diodes (samples 2 and 3) were produced in the same manner as sample 1 except that the area ratio of the gold pattern electrode was changed to 45% and 60% by changing the width of the stripe-shaped electrode. The direct current voltage obtained by the same rectifier circuit as described above was measured and shown in Table 1 below.

(Preparation of sample 4)
The organic semiconductor layer was formed in the same manner as in Sample 1 except that the area occupancy of the gold pattern electrode was changed to 20% by changing the width of the stripe-shaped electrode.
Next, on the organic semiconductor layer, an aluminum thin film having a thickness of 100 nm was formed by mask vapor deposition by vacuum vapor deposition to form an aluminum electrode patterned in a stripe shape. The stripe electrode pattern was formed in a 500 μm × 500 μm electrode formation region in which five stripe-shaped electrodes (length 500 μm, width 20 μm) as shown in FIG. 5 were arranged in parallel at a pitch of 80 μm. The area occupation ratio of the aluminum pattern electrode in the electrode formation region was 20%.
Using the organic diode thus prepared (Sample 4), the DC voltage obtained by the same rectifier circuit as described above was measured and shown in Table 1 below.

(Preparation of samples 5 and 6)
By changing the width of the stripe-shaped electrode, the area occupancy of the gold pattern electrode and the area occupancy of the aluminum pattern electrode were changed to 45% and 70%, respectively. Organic diodes (Samples 5 and 6) were prepared, and the DC voltage obtained by the same rectifier circuit as described above was measured and shown in Table 1 below.

(Preparation of samples 7 and 8)
Organic diodes (Samples 7 and 8) were prepared in the same manner as Sample 1 above, except that the area ratio of the gold pattern electrode was changed to 20% and 70% by changing the width of the stripe-shaped electrode. The direct current voltage obtained by the same rectifier circuit as described above was measured and shown in Table 1 below.

(Preparation of samples 9 and 10)
By changing the width of the stripe-shaped electrode, the area occupancy of the gold pattern electrode and the area occupancy of the aluminum pattern electrode were changed to 10% and 80%, respectively. Then, organic diodes (Samples 9 and 10) were prepared, and the DC voltage obtained by the same rectifier circuit as described above was measured and shown in Table 1 below.

(Preparation of sample 11)
An organic diode (sample 11) was produced in the same manner as in the above sample 1 except that the gold electrode was formed on the entire surface instead of the gold pattern electrode, and a DC voltage obtained by a rectifier circuit similar to the above was applied. The measured values are shown in Table 1 below.

  It is useful in the production of non-contact information media such as organic rectifiers, non-contact IC cards, identification tags, RFID (Radio Frequency Identification) tags such as product tags.

DESCRIPTION OF SYMBOLS 1 ... Organic diode 2 ... Organic-semiconductor layer 3, 4 ... Electrode 4a ... Striped electrode 5 ... Opening 11, 21, 31, 41, 51 ... Organic rectifier 12, 22, 23, 32, 33, 34, 35, 42 , 43, 52, 53 ... Organic diode 71 ... Non-contact information medium 72 ... Resonant circuit 73 ... Rectifier circuit 74 ... Load circuit 83 ... Organic diode

Claims (5)

In an organic diode comprising an organic semiconductor layer as a hole transport layer or an electron transport layer, and a pair of electrodes arranged so as to sandwich the organic semiconductor layer, and rectifies a high-frequency signal ,
At least one of the electrodes has a mesh shape having a plurality of circular openings having an opening diameter in a range of 10 μm to 1 mm in a pitch range of 10 μm to 5 mm, and an electrode material in a range of a width of 10 μm to 1 mm in a honeycomb shape An organic diode, characterized in that it is a patterned electrode of any one of mesh shapes having a plurality of hexagonal openings having an opening length in the range of 10 to 5 mm.   2. The organic diode according to claim 1, wherein one of the electrodes is the pattern electrode, and an area occupation ratio of the pattern electrode in an electrode formation region is in a range of 30 to 70%.   2. The organic diode according to claim 1, wherein the pair of electrodes are both the pattern electrodes, and the area occupation ratio of each pattern electrode in the electrode formation region is in a range of 20 to 80%.   An organic rectifier comprising at least one organic diode according to any one of claims 1 to 3.   At least a resonance circuit for receiving and amplifying a high-frequency signal, a rectification circuit for rectifying the high-frequency signal amplified by the resonance circuit, and a load circuit for driving the drive element by a voltage obtained by the rectification circuit A non-contact type information medium characterized in that the rectifier circuit has at least one organic diode according to any one of claims 1 to 3.

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