JP6232626B2 - Organic molecular transistor - Google Patents

Description

  The present invention relates to a transistor used for signal amplification and the like, and more particularly, to an organic molecular transistor that drives individual organic molecules in synchronization in an organic molecular transistor using organic molecules.

  In a sample in which exciters such as organic molecules are arranged three-dimensionally on the medium, the arrangement method varies depending on the medium carrying the molecules, so that the electromagnetic field environment is affected by the vibrational dipole moment of each molecule. The effects are all different and the way of excitation is different. Therefore, when operating the sum of individual organic molecules as a transistor, by controlling the molecular arrangement of the individual organic molecules, the operation of each organic molecule transistor is synchronized and the entire organic molecule is operated as a transistor. It was.

  That is, in Non-Patent Document 1, it has been clarified theoretically that fluctuations in the surrounding electromagnetic field environment contribute to efficient transmission of molecular excitation between adjacent molecules. Patent Document 1 proposes an organic photoelectric conversion element in which a photoelectric conversion layer is provided between a first electrode and a second electrode. Such a photoelectric conversion layer is obtained by molecular arrangement control of individual organic molecules. Here, the molecular arrangement control means that when organic molecules are supported on a linear medium such as a carbon nanotube, the orientation of the organic molecules is aligned and the intervals between the linear bodies are aligned.

However, when the organic molecule is used as, for example, a substrate supporting carbon nanotubes, the characteristics of the original organic molecular element are exhibited by not controlling the molecular arrangement. There are also fields where it is desired to operate as such a functional element.
In this case, it is necessary for the design and manufacture of functional elements to detect the excitation of individual molecules individually and simultaneously. However, since such a detection method does not exist, there has been no technique for recognizing and discriminating complex and diverse excitation patterns such as organic molecular transistors in multiple dimensions.
Therefore, since organic molecules were controlled to be molecular arrangements to form functional elements, there was a problem that molecular arrangement management in manufacturing was a burden, the manufacturing yield was difficult to increase, and the characteristics of the elements were not stable.

JP 2012-243911 A

S.M.Vlaming and R.J.Silbey, Journal of Chemical Physics, 136, 055102-1-10 (2012)

  SUMMARY OF THE INVENTION An object of the present invention is to provide an organic molecular transistor structure that can be manufactured without controlling the molecular arrangement of organic molecules on carbon nanotubes.

  For example, as shown in FIG. 1, the organic molecular transistor of the present invention includes a grid 10 having an opening capable of supporting a carbon nanotube 20, a grid electrode 12 provided opposite to the grid 10, and the grid 10 and the grid electrode. The carbon nanotubes 20 are located in a parallel space formed between the grids 10 and 12 and have a length longer than the openings formed in the grids 10 and the grid-like electrodes 12. The electron-excitable material 22 held in the gap, the gate electrode 14 positioned close to the parallel space and capacitively coupled to the electron-excitable material 22, and the carbon nanotube 20 and the electron-excitable material 22 are provided. Is characterized in that the molecular arrangement is not controlled.

  In the apparatus configured as described above, the carbon nanotubes 20 have conductivity and are kept in contact with the grid electrodes 12. A switching control signal using a drive signal having a resonance frequency resulting from capacitive coupling with the electron excitable material 22 is sent to the gate electrode 14. Then, the electrons of the electron excitable material 22 are excited by the switching control signal, and a current flows through the lattice electrode 12 through the carbon nanotubes 20. In this way, the organic molecular transistor of the present invention performs an on / off switching operation and operates as a transistor.

In the organic molecular transistor of the present invention, preferably, a hydrophilic functional group is attached to the carbon nanotube.
In the organic molecular transistor of the present invention, preferably, the electron excitable material 22 may include any one of Coumarin 6, porphyrin molecules and derivatives thereof, and an electrically conductive material having electron excitability, or a combination of two or more thereof. .

  In the organic molecular transistor of the present invention, the gate electrode 14 is preferably opposed to the thickness direction of the parallel space at an angle that is not blocked by the grid 10 and the grid electrode 12. As a result, the gate electrode 14 is capacitively coupled to the electron excitable material 22.

  In the organic molecular transistor of the present invention, preferably, the gate electrode 14 is supplied with a voltage higher than the HOMO-LUMO gap voltage of the electron excitable material 22 as a gate voltage and capacitively coupled to the electron excitable material 22. The switching operation is performed by sending a switching control signal having a resonance frequency resulting from the above.

FIG. 1 is a configuration diagram of an organic molecular transistor showing an embodiment of the present invention. FIG. 2 is an equivalent circuit diagram of the organic molecular transistor of the present invention. FIG. 3 is a configuration diagram of a measurement circuit for an organic molecular transistor according to the present invention. FIG. 4 is a current-voltage characteristic between macroelectrodes of the Coumarin 6 molecule and the carbon nanotube. FIG. 5 is a spectrum of the output voltage (upper diagram) and output phase (lower diagram) when the input voltage is fixed at 5 V and the frequency is swept from 0 to 250 kHz. FIG. 6 is a 3D plot corresponding to FIG. 5, where (A) shows the amplitude and (B) shows the phase. FIG. 7 is a dark field image of carbon nanotubes supported on a grid (scale 50 μm).

In this specification, the “vibrating dipole moment” refers to an electric bias inside a molecule or the like that generates a change in the surrounding electromagnetic field.
“Tunnel electron injection” refers to a method of injecting electrons into molecules with energy lower than the height of the tunnel barrier.
“Electromagnetic energy dissipation” refers to a phenomenon in which internal energy such as molecules is lost as electromagnetic energy.

“Excitation transmission” refers to a phenomenon in which a state of high internal energy, such as a molecule, is transmitted to another molecule.
“Tunnel double junction” refers to a structure in which a tunnel barrier is doubled by inserting an intermediate electrode between external electrodes.
“Local environment” refers to a physical state representing an electromagnetic state around an object of about 1 nanometer such as a molecule.

“Derivative” refers to a similar structure constructed by manipulation from the structure of the original molecule.
The “electromagnetic field environment” is a physical quantity that indicates the difference in the surrounding electromagnetic field for the molecule of interest, and the way in which the molecule is excited differs accordingly.
“HOMO” refers to the highest occupied orbit of a molecule.

“LUMO” refers to the lowest unoccupied orbit of a molecule. The organic molecular transistor of the present invention is efficiently excited with the value of the HOMO-LUMO gap.
“Chaos” refers to a complex phenomenon that occurs in systems with nonlinearity. It has a feature that the final convergence value is completely different by a slight change in the initial value.

Hereinafter, the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of an organic molecular transistor showing an embodiment of the present invention. In the figure, the distribution state of the carbon nanotubes 20 and the Coumarin 6 molecules 22 located between the grid 10 and the lattice electrode 12 and the arrangement state of the gate electrode 14 for control are shown. Here, the Coumarin 6 molecules 22 supported on the carbon nanotubes 20 are arranged in a non-uniform state between the grid 10 and the grid electrode 12.

  The dimensions of the grid 10 are not particularly limited as long as the carbon nanotubes 20 can be supported. Usually, the grid 10 has a thickness of 10 nm to 10 μm, a pitch of 120 nm to 120 μm, a bar width of 50 nm to 50 μm, a hole width of 70 nm to 70 μm, The grid 10 has a thickness of 1 μm, a pitch of 12 μm, a bar width of 5 μm, and a hole width of 7 μm. The material is not particularly limited as long as it is conductive, but is preferably made of copper. Here, the bar is a part that forms a partition located between the rectangular holes formed in the grid.

  The size of the grid electrode 12 is not particularly limited as long as the carbon nanotubes 20 can be supported, but the grid electrode 12 is usually 50 nm to 50 μm thick, 500 nm to 500 μm pitch, 350 nm to 350 μm bar width, and 150 nm to 1500 μm hole width. Preferably, the grid electrode 12 has a thickness of 50 nm, a pitch of 500 nm, a bar width of 350 nm, and a hole width of 150 nm. The material is not particularly limited as long as it is conductive, but is preferably made of gold.

  The size of the gate electrode 14 and the distance to the Coumarin 6 molecule 22 are not particularly limited as long as they are capacitively coupled. Is 1 mm in diameter and the distance from the Coumarin 6 molecule 22 is 10 mm.

Although there is no restriction | limiting in the length of the carbon nanotube 20, If it is not longer than the width | variety of the hole of the said electrode, it is preferable that it is 10 micrometers or more from the restriction | limiting that it is not carry | supported by an electrode.
The carbon nanotubes 20 to which the Coumarin 6 molecule 22 and the sulfonic acid derivative which is a hydrophilic functional group are attached are placed in pure water, and ultrasonic waves are applied for 30 minutes to mix them well. Evaporate some water. In addition, when a hydrophilic functional group is not attached to the carbon nanotube 20, a sample can be similarly prepared by placing the Coumarin 6 molecule 22 and the carbon nanotube 20 in ethanol and performing the same operation. The weight ratio of the two is not particularly limited as long as the complexity can be expressed, but is preferably 1: 1.
Usually, tetrahydrofuran (THF) or dimethylformamide (DMF) is used as a solvent in which the carbon nanotubes 20 are dispersed. However, the Coumarin 6 molecule 22 needs to have a property of being well dispersed.

  As a result of the above operation, the Coumarin 6 molecule 22 is supported between the carbon nanotubes 20, thereby forming a tunnel double junction having the carbon nanotube 20 as a microelectrode and the Coumarin 6 molecule 22 as an intermediate electrode. Since the thickness of the sample formed by the Coumarin 6 molecules 22 and the carbon nanotubes 20 is only required to form a tunnel double junction, the minimum is that the Coumarin 6 molecules 22 are supported between 202 carbon nanotubes.

  However, since this transistor exhibits its characteristics more appropriately because there are many tunnel double junctions with different characteristics, basically, there are more tunnel double junctions. Is preferred. On the other hand, if the amount is too large, the current between the two electrodes becomes small, and thus the output voltage becomes small. In this transistor, the thickness of the sample is adjusted so that the current value between the electrodes becomes a predetermined value, for example, 30 μA. It is.

In the apparatus configured as described above, an equivalent circuit diagram and a system for measuring characteristics of the organic molecular transistor as a whole will be described. FIG. 2 is an equivalent circuit diagram of the organic molecular transistor of the present invention. In the figure, the symbol x indicates the tunnel junction 30, the symbol ↑ indicates the constant current source 32, and the wave symbol indicates the high-frequency drive power supply 34 in the circle. . Black circles indicate the Coumarin 6 molecule 22. A tunnel double junction 30 is formed for each of the Coumarin 6 molecules 22. Here, for simplification of illustration, two parallel tunnel junctions 30 are shown, but an actual sample has almost infinite parallel circuits. Capacitance between the gate electrode 14 and the capacitively coupled Coumarin 6 molecule 22 is indicated by C _{1 and} C ₂ . Since generally the capacitance between the gate electrode 14 and each of Coumarin6 molecules 22 all different, generally represents the electrostatic capacitance and _{C n.}

  FIG. 3 is a configuration diagram of a measurement circuit for an organic molecular transistor according to the present invention. The control computer 40 manages instruction signals and measurement signals for the constant current source 32 and the lock-in amplifier 42. The lock-in amplifier 42 receives a high-frequency signal given from the outside as a reference signal, and detects a frequency component equal to the reference signal. In the lock-in amplifier, among the various signals included in the measurement signal, only the component equal to the reference signal frequency becomes a direct current and can pass through the LPF, but the other components are converted into an alternating current signal with a frequency ≠ 0 Hz. Removed. In this way, the lock-in amplifier can extract a signal component from which noise has been removed, and thus is suitable for use in a signal having a large noise. The sample 16 is configured to include the Coumarin 6 molecule 22 and the carbon nanotube 20 and includes an appropriate solvent.

In the measurement system configured as described above, the electrical characteristics of the organic molecular transistor are measured as follows.
First, as shown in FIG. 1, the gate electrode 14 is disposed outside the grid 10 and the grid electrode 12. Next, as shown in FIG. 2, by applying a bias voltage to the gate electrode 14, the carbon nanotube 20 is used as a micro electrode and a gate voltage 5V is applied to each Coumarin 6 molecule 22 for control (this structure is complicated). Called organic molecular transistor).

  Next, in the measurement circuit as shown in FIG. 3, a constant current source 32 is used to apply a constant current of 0.25 V and 30 μA between the grid 10 and the grid electrode 12 to control the organic molecular transistor. . As a result, tunnel electrons are injected into the Coumarin 6 molecule 22. On the other hand, the high frequency output voltage (Amplitude V) of the lock-in amplifier 42 is capacitively coupled to the Coumarin 6 molecule 22 as a control gate bias. Therefore, the device using the organic molecular transistor of this embodiment has a structure that is controlled by a high-frequency gate voltage in a constant current application state. The output voltage (Voltage magnitude R) and phase (Voltage phase θ) are read from one end of the device.

Next, the current-voltage characteristics between macroelectrodes of Coumarin 6 molecules and carbon nanotubes measured by such a measurement circuit will be described.
FIG. 4 is a current-voltage characteristic between macroelectrodes of the Coumarin 6 molecule and the carbon nanotube. When the current-voltage characteristics between the sample grid 10 and the grid electrode 12 as shown in FIG. 1 were measured, nonlinear characteristics were shown as shown in FIG. FIG. 4 shows the characteristics when the applied voltage is applied a plurality of times, and shows slightly different characteristics for each application. This indicates that the excitation method varies depending on the application.

  Next, the high-frequency applied voltage of the lock-in amplifier 42 was fixed to 5 V, the frequency was swept from 0 to 250 kHz, and the frequency dependence of the output voltage and phase was measured at the device output end. FIG. 5 is a spectrum of the output voltage (upper diagram) and output phase (lower diagram) when the input voltage is fixed at 5 V and the frequency is swept from 0 to 250 kHz. In all measurements, the time constant of the lock-in amplifier 42 was 1 second, the number of measurement points was 2000, and the interval between the measurement points was 500 milliseconds. As shown in the upper diagram of FIG. 5, the output voltage showed a high output voltage at 61,906 Hz. This fact indicates that the Coumarin 6 molecule 22 inserted into the device by several orders of Avogadro had a simultaneous response (resonance phenomenon) at this frequency even though the electromagnetic field environment around each molecule was different. . As shown in the lower diagram of FIG. 5, there was no significant change in the phase at this frequency.

Subsequently, the applied voltage of the lock-in amplifier 42 was fixed to 5 V, the sweep frequency was fixed to the resonance frequency 61,906 Hz, and the time change of the output voltage and the output phase was measured. The purpose of performing this measurement is to clarify whether the characteristic obtained in FIG. 5 is seen only when the sweep frequency is swept, or whether the characteristic is seen when the frequency is fixed. According to the measurement result, the output voltage vibrated violently between 0 (5.1 × 10 ⁻²¹ ) and 4.5 × 10 ⁻⁵ [V]. The output phase violently oscillated between −π (−180 °) and + π (180 °). Phase oscillation is a phenomenon frequently seen when the output voltage is small. When the output voltage was about 1.5 × 10 ⁻⁵ [V], the phase showed a relatively stable value of about θ = 90 ° (π / 2).

  Next, the sweep frequency was fixed at a resonance frequency of 61,906 Hz, the applied voltage was swept between 0 and 5 [V], and the dependence of the output voltage and the output phase was measured. The purpose of this measurement is to clarify whether the characteristic obtained in FIG. 5 is seen only when the frequency is swept or whether the characteristic is also seen when the applied voltage is swept. Then, as the measurement time elapses, the output voltage almost monotonously increases, and the phase vibrates violently while the output voltage is small (up to about 1.2 [V]) as shown in the figure below. A stable value was exhibited at approximately θ = 90 ° (π / 2). Again, phase instability was observed while the output voltage was small.

Next, the high frequency applied voltage was fixed to 5 V, the frequency was swept from 0 to 250 kHz, and the frequency dependence of the output voltage and phase was measured at the device output end. Then, the output voltage showed a high output voltage at 59,530 Hz. Despite using the same setup as the measurement of FIG. 5, the resonant frequencies are slightly different.
Next, the applied voltage was fixed at 5 V, the sweep frequency was fixed at a resonance frequency of 59,530 Hz, and the time change of the output voltage and output phase was measured. Here, both the output voltage and the phase oscillate until a predetermined time elapses, but converge after the predetermined time.

Next, the sweep frequency was fixed to 250,000 Hz (the maximum sweep frequency of the lock-in amplifier 42), the applied voltage was swept between 0 and 5 [V], and the dependence of the output voltage and the output phase was measured. . As a result, the output voltage increased slightly. When the output voltage is small, the output phase violently oscillates between -π and + π. Phase oscillation is a phenomenon frequently seen when the output voltage is small.
Next, the high frequency applied voltage was fixed to 5 V, the frequency was swept from 0 to 250 kHz, and the frequency dependence of the output voltage and phase was measured at the device output end. Then, the output voltage showed a high output voltage at the first resonance frequency of 33,892 Hz and the second resonance frequency of 79,164 Hz. Despite using the same setup as the measurement of FIG. 5, the resonant frequencies are very different.

  Next, the applied voltage was fixed at 5 V, the sweep frequency was fixed at the first resonance frequency of 33,892 Hz, and the time variation of the output voltage and output phase was measured. In this case, both the output voltage and the phase oscillate relatively between the first predetermined time and the second predetermined time. At this time, the control program of the control computer 40 is set to “sweep frequency”.

  Next, the applied voltage was fixed at 5 V, the sweep frequency was fixed at the first resonance frequency of 33,892 Hz, and the time variation of the output voltage and output phase was measured. Here, a vibration tendency was observed over almost the entire measurement time. At this time, the control program of the control computer 40 is set to “sweep applied voltage”. In this way, the same value is set at the start and end of measurement so that the applied voltage and frequency do not change substantially, but the cause of the difference between the applied voltage sweep and the frequency sweep is not clarified. .

  Next, the applied voltage was fixed at 5 V, the sweep frequency was fixed at a non-resonant frequency of 30,892 Hz, and the time change of the output voltage and the output phase was measured. At this time, a sudden increase in output voltage and phase convergence were observed in the third predetermined time. At this time, the control program of the control computer 40 is set to “sweep frequency”.

  Next, in the case where the applied voltage was 5 V and the sweep frequency was 2 resonance frequencies under the above-described measurement conditions, the second resonance frequency was fixed at 79,164 Hz, and the time variation of the output voltage and output phase was measured. . At this time as well, vibration was observed within the measurement time range. At this time, the control program of the control computer 40 is set to “sweep frequency”.

Next, the applied voltage was fixed at 5 V and the sweep frequency was fixed at the second resonance frequency of 79,164 Hz, and the time change of the output voltage and output phase was measured. At this time, it vibrated vigorously between the elapse of the fourth predetermined time and the elapse of the fifth predetermined time. However, except for this range, the measurement result in the above-described “sweep frequency” mode is almost the same. At this time, the control program of the control computer 40 is set to “sweep applied voltage”.
In the above measurement, the output voltage is on the order of 10 ⁻⁵ [V], which is sufficiently higher than the noise level, and the difference in the measurement is a significant result.

  Next, it was analyzed whether the measurement results shown above were noise or a mathematical structure could be seen. FIG. 6 is a 3D plot corresponding to FIG. 5, where (A) shows the amplitude and (B) shows the phase. Here, the 3D plot displays all measurement points (n, n + 1, n + 2) in three dimensions (x, y, z). Each point was displayed by the method of (n, n + 1, n + 2), (n + 1, n + 2, n + 3),. An overall view of the measurement point set structure is shown, and each scale is changed so that details are as clear as possible. The magnifications can be roughly compared by the lengths of the three axes. The longer the shaft length, the greater the magnification. Further, the density of each point is distinguished as follows. The dark display is the beginning of measurement, and the light display is close to the end of measurement. Thereby, an approximate time evolution can also be read from the 3D plot.

Further, according to the 3D plot, a clear structure appears in the 3D plot when the sweep voltage and the frequency are fixed as compared with the frequency sweep and the voltage sweep.
On the other hand, mathematically, if the data is noise, no structure appears in the 3D plot. Thus, the above results indicate that the plot showing the structure is not noise. The cause of these structures can be considered as follows.

That is, for the distribution of the above three-dimensional plot, there is a principle that the way of molecular excitation changes depending on the electromagnetic field environment of the molecule. Therefore, the excited state of the molecule differs depending on how the Coumarin 6 molecule 22 supported on the carbon nanotube 20 is supported and how the carbon nanotube 20 is distributed in the space. Accordingly, the excitation distributions are all different depending on the method for preparing the carbon nanotube 20 and the Coumarin 6 molecule 22 sample. When a device is fabricated using such a large number of molecules, the excitation of individual molecules is all different. However, when looking at the properties of the device as a whole, the different states of excitation of individual molecules are not just random states.
Thus, it was confirmed that the output was controlled by the gate electrode by three-dimensional plotting and visualizing each of the output voltage and the phase point (n, n + 1, n + 2).

  Therefore, there is no other one that shows the same distribution as the excitation distribution shown in the above embodiment, and each molecule has a very unique excitation pattern. The variety of distribution of the carbon nanotube 20 is shown as an example that each molecule is in a different state.

FIG. 7 is a dark field image of carbon nanotubes supported on a grid (scale 50 μm). In FIG. 7, the manner of non-uniform distribution of the carbon nanotubes 20 in the space is shown using an electron micrograph.
As can be seen from this figure, it is clear that the carbon nanotubes 20 have different distributions at different locations at the micro level. This causes changes in the electromagnetic field environment. In the electron microscope, the Coumarin 6 molecule 22 is not shown as an image for reasons such as resolution, but it has been confirmed by light emission by laser excitation that the Carbonine 6 molecule 22 is supported on these carbon nanotubes 20.

  As described above, according to the organic molecular transistor of the present invention, it can be used for various electronic components used in electronic devices using a large number of organic molecules. That is, since each molecule is excited by each electromagnetic field environment, it is impossible to control the excitation of individual molecules from the outside. However, when viewed as a total device, if it responds to an external control signal as the sum of molecules, macro control is possible.

The present invention is not limited to the above-described embodiments, and various modifications as described below are possible by those skilled in the art.
(I) The electron-excitable material held under the lattice electrode is not limited to organic molecules including Coumarin 6, porphyrin molecules and derivatives thereof, and may be conductive materials. The present technology is universally applicable if the material is electronically excited.
(Ii) The carbon nanotubes are not limited to those attached with the sulfonic acid derivatives used in the examples of the present invention, and carbon nanotubes with other functional groups function in the same manner as long as they appropriately bond to molecules. .
(Iii) The grid electrode is not limited to the size shown in the embodiments of the present invention. It is sufficient that the pitch of the lattice is equal to or less than the length of the carbon nanotube.

(Iv) If the grid also has an opening, the grid functions similarly if the condition (iii) is satisfied. Even a substrate made of indium tin oxide functions similarly because of its electrical conductivity.
(V) The voltage / current applied between the grid electrode and the grid is not limited to 0.25 V, 30 μA, and an appropriate value can be selected.
(Vi) The voltage is not limited as long as the gate voltage is equal to or greater than the HOMO-LUMO gap value (approximately 4 V) of the electron-excitable material (Coumarin 6 molecule).

(Vii) In the analysis of the measurement result, the case of the distribution of the three-dimensional plot is shown, but the distribution display of four or more multi-dimensional plots may be used. Although human beings can visually follow only three dimensions for multidimensional display, mathematically, in general, n dimensions are possible, and n can be an arbitrary number of 4 or more.
(Viii) In the analysis of the measurement result, in the distribution of the three-dimensional plot, each point display is limited to the methods of (n, n + 1, n + 2), (n + 1, n + 2, n + 3),. In addition, (n, n + 1, n + 2), (n + 2, n + 3, n + 4), etc. can be used to make the mathematical structure clear.

  According to the organic molecular transistor of the present invention, it is manufactured using a large number of organic molecules and can be used for various electronic components used in electronic equipment.

10 Grid 12 Grid electrode 14 Gate electrode 16 Sample 20 Carbon nanotube 22 Coumarin 6 molecule (electron-excitable material)
30 Tunnel double junction 32 Constant current source 34 High frequency drive power supply 40 Control computer 42 Lock-in amplifier

Claims (5)

A grid having openings capable of supporting carbon nanotubes;
A grid electrode provided opposite to the grid;
The carbon nanotubes located in a parallel space formed between the grid and the grid electrode and having a length longer than the opening formed in the grid and the grid electrode;
An electron-excitable material held in a gap formed in the aggregate of the carbon nanotubes;
A gate electrode located close to the parallel space and capacitively coupled to the electron excitable material;
An organic molecular transistor, wherein the carbon nanotube and the electron-excitable material are arranged in a state where molecular arrangement is not controlled.   The organic molecular transistor according to claim 1, wherein a hydrophilic functional group is attached to the carbon nanotube.   3. The electron-excitable material includes any one of Coumarin 6, porphyrin molecules and derivatives thereof, and a conductive material having electron-excitability, or a combination of two or more thereof. Organic molecular transistor.   4. The organic molecular transistor according to claim 1, wherein the gate electrode is opposed to the thickness direction of the parallel space at an angle that is not blocked by the grid and the grid electrode. 5. A voltage higher than the HOMO-LUMO gap voltage of the electron excitable material is supplied to the gate electrode as a gate voltage, and a switching control signal having a resonance frequency due to capacitive coupling with the electron excitable material is sent to the gate electrode. The organic molecular transistor according to claim 1, wherein a switching operation is performed.