JPH0279401A - Nonlinear electric conduction element - Google Patents

Abstract

PURPOSE:To obtain a nonlinear electric conduction element utilizing negative resistance phenomenon by making an ionic organic charge transfer complex, which has specific charge transfer degree and shows negative resistance, a main component. CONSTITUTION:An ionic organic charge transfer complex which has a negative resistance phenomenon at a charge transfer degree of 0.4 or more with temperatures of 100K or more is made a main component. The ionic organic charge transfer complex consists of an electron donor and an electron acceptor. For the electron donor, preferably an organic electron donor having a conjugated system, or more preferably a conjugated organic electron donor having a circular structure is used. For the electron acceptor, preferably an organic electron acceptor having a conjugated system, or more preferably a conjugated organic electron acceptor having a circular structure is used.

Description

DETAILED DESCRIPTION OF THE INVENTION (3-1) The present invention relates to a molecular electronic device having nonlinear electrical conductivity. Specifically, the present invention relates to a nonlinear electrically conductive element that utilizes the negative resistance phenomenon of ionic organic charge transfer complexes to exhibit functions such as switching, memory amplification, logic, and arithmetic.

(3-2) A high-performance molecular device using five organic substances is Obtoe 1/
It is required for the development of kutronics. In particular, there are strong expectations for the realization of nonlinear conduction elements that exhibit functions such as switching and memory.

Recently, R, S, Potember, etc. are Cu/TCNQ
discloses a novel electrically conductive element having switching and memory phenomena in thin films (TLS4507672).
．． 1985; R,S.

Potember, etal,, Appl, Phy
Lett, + 1979. Vol.

34, PP405). Metals include copper, silver, and acceptor. :, TCNE, TCNQ, TCN
Q derivatives, TNAP (7-tradiatunaphthoquinodimethane), and the like. Depending on the strength of the acceptor, the switching operation changes to threshold type, memory type, etc.

These phenomena are caused by Cu'/TCN (1" is Cu'/TC
The appearance of a mixed valence state due to a partial change to NQ' results in a change from a low conductivity state to a high conductivity state, which is essentially phase change based and irreversible.

Moreover, it has no negative resistance at all. That is, it does not exhibit hysteresis in its current/voltage characteristics, and is completely unsatisfactory functionally as a nonlinear electric element.

Recently, the inventors have discovered that TTF (tetrathiofulvalene)/
We found that the CA (chloranil) system expressed negative resistance (+Kura, 1986 Fall Proceedings of the Physical Society of Japan, P137; Y, Tokura, etal,, P
hysica 14385271986). This is attracting much attention as the first case in which negative resistance has been truly confirmed. T
The TF/CA system is a neutral organic charge transfer complex with a charge mobility of 0.3 and is the only one that exhibits a neutral-ionic transition under normal pressure.

However, the appearance of dietary resistance is limited to relatively low temperatures;
In the air, it is unstable and deteriorates due to the influence of humidity. Particularly in the case of thin films that are important as elements, they become extremely unstable.

(3-3) is stable in the section we are trying to solve,
We have discovered a material that has high negative resistance at high temperatures, that is, a material with hysteresis in current/voltage characteristics, which is useful as a main component of a nonlinear electrically conductive element, and created a nonlinear electrically conductive element that utilizes this negative resistance phenomenon. It provides:

(3-4)! As a result of intensive technical studies, the present inventors discovered a highly useful nonlinear electrically conductive element.

That is, the present invention is a nonlinear electrically conductive device characterized in that the main component thereof is an ionic organic charge transfer complex having a negative resistance phenomenon at a charge mobility of 0.4 or more at a temperature of 100°C or more.

(3-4-1) Organic charge transfer complex The ionic organic charge transfer complex of the present invention is an electron donor (D).
and an electron acceptor (8).

An organic electron donor of Rigoku temporary donor-i can be used, preferably an organic electron donor having a conjugated system, more preferably a conjugated organic electron donor having a cyclic skeleton.

An example is given below.

(11 Fullvalene Derivatives Here, X and ~x4 are hydrogen atoms, halogen atoms, alkyl groups having 1 to 20 carbon atoms (e.g., methyl group, ethyl group, etc.), alkoxy groups (e.g., methoxy group).

(ethoxy group, etc.), alkylthio group, aryl group (eg, phenyl group, tolyl group, etc.), aryloxy group, arylthio group, amino group, hydroxyl group, etc., and composite groups thereof can be used.

For X and ~X#, different atoms or groups may be used, or a plurality of atoms or groups of the same type may be used.

Y, to Y2 are group IIb atoms such as sulfur and selenium.

Tellurium etc. can be used. Y and Y may each use different atoms, or may use the same type of atoms.

(2) Phenylenediamine derivative X5
etc.), alkoxy groups (eg, methoxy groups, ethoxy groups, etc.), alkylthio groups, aryl groups (eg, phenyl groups, tolyl groups, etc.), aryloxy groups.

Arylthio group, amino group, hydroxyl group, etc.

and complex groups thereof can be used.

Islands to X6 may each use different atoms or groups,
A plurality of atoms or groups of the same type may be used.

(3) Benzidine derivatives Here, x1 to Kll are hydrogen atoms, halogen atoms, alkyl groups having 1 to 20 carbon atoms (e.g., methyl group, ethyl group, etc.), alkoxy groups (e.g., methoxy group, ethoxy group, etc.), alkylthio groups, aryl groups (e.g. phenyl group, tolyl group, etc.), aryloxy group.

Arylthio group, amino group, hydroxyl group, etc.

and complex groups thereof can be used.

For X and ~X, different atoms or groups may be used, or a plurality of atoms or groups of the same type may be used.

(4) Phenazine derivative X.

Here, X, X are hydrogen atoms, halogen atoms, alkyl groups having 1 to 20 carbon atoms (e.g. methyl group, ethyl group, etc.)
, alkoxy group (e.g., methoxy group, ethoxy group, etc.)
, alkylthio group, aryl group (e.g. phenyl group,
tolyl group, etc.), oriroxy group.

Arylthio group, amino group, hydroxyl group, etc.

and complex groups thereof can be used.

For XI and XI, different atoms or groups may be used, or a plurality of atoms or groups of the same type may be used.

(5) Phenothiazine derivative where X is a hydrogen atom, a halogen atom, and has 1 to 20 carbon atoms.
Alkyl groups (e.g. methyl, ethyl, etc.), alkoxy groups (e.g. methoxy, ethoxy, etc.), alkylthio groups, aryl groups (e.g.

phenyl group, tolyl group, etc.), aryoloxy group, arylthio group, amino group, hydroxyl group, etc., and composite groups thereof can be used.

1) General organic electron acceptors can be used, preferably organic electron acceptors having a conjugated system, more preferably conjugated organic electron acceptors having a cyclic skeleton.

An example is given below.

(fl tetracyanoquinodimethane derivative, where X l
``'
Azide group, hydroxyl group, carboxyl group, nitro group, and alkyl group having 1 to 20 carbon atoms (e.g. methyl group,
(ethyl group, etc.), alkoxy groups (eg, methoxy group, ethoxy group, etc.), alkylcarbonyl groups, aryl groups, arylcarbonyl groups, and composite groups thereof can be used.

For x1 to X4, different atoms or groups may be used, or a plurality of atoms or groups of the same type may be used.

(2) Tetracyanonaphthoquinodimethane derivative xS
XI Here, XI-Xb is a hydrogen atom, a halogen atom (e.g., a fluorine atom, a chlorine atom, a bromine atom, an iodine atom), a cyano group, an azide group, a hydroxyl group, a carboxyl group, a nitro group, and a carbon number of 1 to 20 Alkyl groups (eg, mekyl group, ethyl group, etc.), alkoxy groups (eg, methoxy group, ethoxy group, etc.), alkylcarbonyl groups, aryl groups, arylcarbonyl groups, etc., and composite groups thereof can be used.

For X I''' X b, different atoms or groups may be used, or a plurality of atoms or groups of the same type may be used.

Here, X I"" X * is a hydrogen atom, a halogen atom (
For example, fluorine atom, chlorine atom, bromine atom, iodine atom).

Cyano group, azide group, hydroxyl group, carboxyl group, nitro group, alkyl group having 1 to 20 carbon atoms (e.g., methyl group, ethyl group, etc.), alkoxy group (e.g., methoxy group, ethoxy group, etc.), alkylcarbonyl group , an aryl group, an arylcarbonyl group, and a composite group thereof can be used.

For Xo and ~X#, different atoms or groups may be used, or a plurality of atoms or groups of the same type may be used.

(4) Fluorenone derivative XS XI Xs OL Here, X1 to Xs are a hydrogen atom or a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom).

cyano group, azide group, hydroxyl group, carboxyl group, nitro group, alkyl group having 1 to 20 carbon atoms (e.g. methyl group, ethyl group, etc.), alkoxy group (e.g. methoxy group, ethoxy group, etc.), alkylcarbonyl group, Aryl groups, arylcarbonyl groups, etc., and composite groups thereof can be used.

For X and ~X, different atoms or groups may be used, or a plurality of atoms or groups of the same type may be used.

An ionic organic charge transfer complex is prepared from the above electron donor D) and an electron acceptor. Manufacturing methods include solution mixing method, solution diffusion method, electric field method, and co-sublimation method.

A binary vapor deposition method or the like can be used. In the present invention, (D
Although the combination of ) and (A) is not particularly limited, the ionic complex must satisfy the following conditions.

The ionic organic charge transfer complex has a charge mobility (ρ) of 100 or more, preferably 0.4 or more, preferably 0.5 or more, and more preferably 0.55 or more. Here, the charge mobility (ρ) is defined as the electron donor (D) and electron acceptor (A) pair (
DA), it shows the rate of charge transfer from the electron donor (D) to the electron acceptor (D″fiA-fi>. In other words, the charge transfer rate between the electron donor and the electron acceptor is When there is no molecule and each is a neutral molecule (D'A'), the charge mobility is O, and the charge is completely transferred from the electron donor to the electron acceptor, and the ionic molecule (D''A-) and When , the charge mobility is 1. This charge mobility is
It is determined experimentally by molecular vibrational analysis of infrared absorption spectra, bond analysis by X-ray diffraction, and atomic valence analysis by ESCA (XPS).

The ionic organic charge transfer complex consisting of (D) and (A) is
It can have a separate layered or alternately layered crystal structure, preferably an alternately layered crystal structure. Here, the alternating layered crystal structure is DADADADA...DDA
It has a crystal structure in which (D) and (A) are alternately stacked like ADDAADDAA. Such a structure can be determined by X-ray diffraction.

Examples of ionic organic charge transfer complexes that satisfy the above conditions are listed below.

(TCNQ) (N, N', N, N' TMPDn
(T(1:Ng)(3-4-
2) Single crystallization and thin film formation of organic charge transfer complex The present invention includes:
A single crystal or polycrystal of the above-mentioned ionic organic charge transfer complex is used in the form of a bulk or a thin film as a main component of a nonlinear electrically conductive device.

A common method can be used to prepare the single crystal.

Examples include a co-sublimation method, a solution mixing method, a solution diffusion method, an electrolytic method, a solution concentration method, etc. (Reference: "-Dimensional Electrical Conductor" edited by Kagoshima region (Shokabo) P, P, 53-57).

A general method can be used to adjust the thin film.

For example, two-dimensional vapor deposition method, co-sublimation method, etc. The substrate used for thinning is not particularly limited, but metals, semiconductors, polymers, glass, etc. can be used.

Here, among single crystals or polycrystals of organic charge transfer complexes in a bulk or thin film state, those having an alternating layered structure of electron donors and electron acceptors are preferable.

(3-4-3) Negative resistance In the present invention, it was discovered for the first time that an ionic organic charge transfer complex exhibits negative resistance and has unique nonlinear electrical conductivity. It was found that strong non-ohmic conductive behavior is exhibited both in the positive resistance region and in the positive resistance region.

In the present invention, exhibiting negative resistance means that the current-voltage characteristics are negative, and in addition to being negative under the conditions in which the obtained element is used, when the temperature etc. are set to certain specific conditions. It may also exhibit negative characteristics.

This unique negative resistance phenomenon can be confirmed in the following experiment. As shown in FIG. 1, a bias resistor Rt is connected in series to the ionic complex 1, and changes in current due to voltage are measured. In addition, in the figure, v0 is a power supply voltage, and A is an ammeter.

■ is the current.

The nonlinear current-voltage characteristics in the present invention are schematically shown in FIG.

From FIG. 2, it was confirmed that this device has hysteresis and two threshold values. This element can be caused to transition from a low conductivity state Ua to a high conductivity state Bb by applying a voltage exceeding the high voltage side threshold value ν1. Further, from the highly conductive state 6b, the applied voltage is set to the low voltage side threshold v
By lowering the voltage below 2, the low conductivity state a
It is possible to return to

This nonlinear electrical conduction phenomenon has temperature dependence (FIG. 3) and bias resistance dependence (FIG. 4).

That is, as the temperature decreases and the bias resistance decreases, nonlinearity becomes significant and switching accompanied by hysteresis is exhibited.

This nonlinear electrical conduction phenomenon is expressed as the relationship between the electric field E directly applied to the ionic complex and the current density log I as shown in FIG. This shows that the ionic complex exhibits negative resistance. Furthermore, it can be seen that strong non-ohmic conduction is exhibited even in the positive resistance region.

(3-4-4) Configuration of nonlinear electrical conduction element (3-4-3
) It is possible to develop various nonlinear electrical conductions by utilizing the negative resistance found in Various configurations of the device are possible as shown in the examples below, but the essential condition is to use the ionic complex of the present invention as a main component and to utilize the negative resistance of this ionic complex.

[Example 1] A method can be used in which the single crystal 1a of the ionic complex is used and a voltage is applied via a bias resistor in the direction of alternate stacking of constituent molecules (FIG. 6(a)).

The arrow in the figure indicates the stacking direction of the electron donor (D) and electron acceptor (A) of the ionic organic charge complex. Furthermore, the ionic complex single crystal can be used as a bias resistance in the direction perpendicular to the direction of alternate stacking. These two examples 1b.

Ic is shown in Figure 6 (bl).

[Example 2] FIG. 7 (polycrystals of the ionic complex as shown).

A thin film compound 1d can be used. The electrode configuration can be a vertical electrode in which a thin film is sandwiched between the positive and negative electrodes 3.4 as shown in Figure 7, or a horizontal electrode in which the positive and negative electrodes are arranged on one side as shown in Figure 87 (C1). Also, Fig. 7(d)
It is also possible to construct horizontal electrodes on both sides of the thin film as shown. Further, the electrode area is not particularly limited.

Note that although a bias resistor is normally used, it may be omitted.

[Example 3] It is also possible to use a polycrystalline powder of the ionic complex dispersed in a dispersant such as a polymer. The electrode structure similar to that shown in FIG. 7 [Example 2] can be used.

Note that although a bias resistor is normally used, it may be omitted.

Example C 4] For example, it is possible to use a dispersed thin film and a polycrystalline thin film to form an electrode structure in which a large number of electrodes are arranged in parallel as shown in FIG. The crystal state (single crystal, polycrystal) and shape (bulk, thin film) of the ionic complex are not particularly limited, but the electrode may be one-dimensional (FIG. 8(a)).

A large number of them arranged two-dimensionally (FIG. 8(b)) or three-dimensionally (FIG. 8(C)) are used.

Note that although a bias resistor is normally used, it may be omitted.

(3-4-5) Function of nonlinear electrically conductive element The nonlinear electrically conductive element of the present invention utilizes the strong non-ohmic electrical conduction and negative resistance phenomena of the ionic organic charge transfer complex to perform switching, memory, Expresses functions such as amplification, logic, and calculation.

As shown in (3-4-3), the device according to the present invention can change its nonlinear current-voltage characteristics by changing the temperature and bias resistance (see FIGS. 3 and 4). Therefore, various functions can be easily realized by changing the element configuration shown in (3-4-4), especially the bias resistance. For example, by reducing bias resistance and current −
Under conditions where the voltage characteristics have hysteresis, functions such as switching, storage, amplification, logic, and calculation using bistability can be realized. Furthermore, depending on the element configuration, these functions can be easily processed in parallel. In addition, when light is irradiated onto the element, the heat mode and photon mode are utilized to achieve the above-mentioned switching, memory, amplification, and logic.

Functions such as arithmetic operations can be performed.

Note that, as shown in Examples, the element in the present invention has I
Drive such as switching is possible with a low electric field of about V/μ-.

g'' and 1-Toyokazu [Examples 1 to 4] Using the electron donors and electron acceptors shown in Table 1, single crystals were grown according to the preparation method shown in Table 2. When the charge mobilities were measured at 25° C. using an infrared absorption method, the charge mobilities were all 0.5 or more as shown in Table 2, confirming that they had ionicity. Further, when the laminated structure was confirmed by X-ray diffraction method, it was confirmed that all the samples had an alternate laminated structure as shown in Table 2.

Electrodes shown in Table 3 were formed, and a nonlinear electrical conduction element shown in FIG. 6(a) was produced. When the voltage-current characteristics were measured for each Kelvin temperature K using the two-terminal method shown in FIG. 1, it was confirmed that there was hysteresis as shown in FIGS. 9.11.13.15. When this is expressed in terms of the relationship between the electric field and current density directly applied to the complex, it becomes as shown in Figure 10.12.14.16, and it was confirmed that negative resistance was expressed.

As described above, we have found that it is possible to fabricate a unique nonlinear electrically conductive device by using these ionic organic charge transfer complexes as the main constituents and utilizing the negative resistance of these complexes.

Table 1 Inu-ichiichi Shadow Table 3 [Example 5] Regarding the nonlinear electrically conductive element used in Example 2, 205
68V at K centering +10v and -10v.

When a pulsed electric field E1 with a duration of 1 ms was applied at intervals of 10 m5, it was confirmed that it had a bistable switching function, as shown in FIG. 17.

Note that this switching could be repeated 106 times or more.

As described above, it has been found that the nonlinear electrical conduction element of the present invention stably has a current switching function by voltage control.

[Example 6] Regarding the nonlinear electrically conductive element used in Example 1, 21'
The bias resistance value was changed at 8K. As shown in Figure 18, as the resistance value is reduced from 100MΩ,
The rise of the applied voltage of 600V becomes steep, and the voltage rises to 10M.
Hysteresis was confirmed in Ω. It has been found that the change in current-voltage characteristics due to the bias resistance described above is reversible, and that by changing the bias resistance value, it is possible to fabricate a stable nonlinear electrical conduction element at a voltage of 100 or more.

Furthermore, it was confirmed that by changing the bias resistance value, it is possible to control functions such as switching, memory, amplification, and calculation of the element.

[Brief explanation of the drawing]

Figure 1 is a current-voltage characteristic evaluation circuit diagram of a nonlinear electrical conduction element, Figure 2 is a diagram showing typical current-voltage characteristics with hysteresis of a nonlinear electrical conduction element, and Figures 3 and 4 are diagrams of the element. A diagram showing the temperature and bias resistance dependence of nonlinear current-voltage characteristics. Figure 5 is a diagram showing the temperature dependence of the negative resistance of an ionic charge transfer complex. Figure 6 (a), (bl,
FIGS. 7(a) to (d) and FIGS. 8(a) to (C) are explanatory diagrams showing the structure of the element, respectively, and FIGS. 9 to 16 are explanatory diagrams showing the structure of the device in Examples 1, 2, and 3.4, respectively. FIG. 17 is a diagram showing the current-voltage characteristics of the device and the negative resistance of the ionic charge transfer complex; FIG. 17 is a diagram showing the switching characteristics of the device in Example 5;
Figure 8 shows the bias resistance of the current-voltage characteristics of the device in Example 6. Answer 6' Drama (old up) Answer ■ Can (b) 2-dimensional et al. (C) 3-dimensional object hidden Ki H mouth E (KV/c 7? 2) Ki II? country

Claims (1)

[Claims] The charge mobility is 0.4 or more at a temperature of 100K or more,
What is claimed is: 1. A nonlinear electrical conduction element characterized in that the main component thereof is an ionic organic charge transfer complex exhibiting negative resistance.