Bias voltage response type switch based on two-component molecular system and preparation method and application thereof

Abstract

The invention discloses a bias voltage response type switch based on a two-component molecular system and a preparation method and application of the bias voltage response type switch. The switch comprises a bottom electrode, a bimolecular functional layer and a top electrode; wherein the bimolecular functional layer is obtained by respectively dissolving a component A and a component P in an organic solvent and then mixing according to a molar ratio of 1: 1; the component A is a non-conjugated compound of which the end group is modified with a sulfydryl anchoring group, and the HOMO-LUMO energy level gap delta E is 3.5-4.2 eV; the component P is a small molecule compound with a conjugated pi electron system, and the HOMO-LUMO energy level gap delta E is 2.1-2.3 eV. Precise switching of two conductance states is achieved through bias voltage amplitude regulation and control, meanwhile, the device has the advantages of being stable in state, adjustable in threshold value and easy and convenient to prepare, and the application requirements of a molecular logic circuit and information storage are met.

Description

Technical Field

[0001] This invention relates to the field of molecular electronics and molecular switching technology, specifically to a bias-responsive switch based on a two-component molecular system, its fabrication method, and its application. Background Technology

[0002] Molecular switches, as core devices in molecular electronics, achieve "on / off" or multi-state switching through external stimuli (such as light, electrical, and chemical signals), possessing irreplaceable advantages in fields such as high-density information storage and micro-logic circuits. Existing molecular switches mostly rely on the structural isomerization of a single component (such as photoinduced cis-trans isomerization and electroinduced redox) to achieve state switching, which has the following technical drawbacks: (1) Single response: Most switches can only achieve "single stimulus-single state" switching (such as only light control or only electrical control), which is difficult to meet the needs of multi-signal coordinated regulation in complex scenarios; (2) Poor state stability: Single-component isomerization is easily affected by environmental disturbances (such as temperature and solvent polarity), leading to relaxation of the switching state (such as easy recovery of photo-induced isomers in the dark state) and short cycle life (usually <10). 3 Second-rate); (3) Low threshold controllability: The stimulus response threshold (such as light intensity and voltage) of the switch is determined by the intrinsic molecular structure, and it is difficult to achieve threshold customization through simple adjustment to adapt to different application scenarios; Therefore, developing a molecular switch with "polymorphic response, high stability, and adjustable threshold" has become key to overcoming the bottlenecks of existing technologies. In this invention, the A and P binary molecular system can achieve selective conductivity activation of the two components under bias voltage control. Its dual-state response characteristics of "low bias voltage - A state, high bias voltage - P state" provide a novel approach for constructing high-performance molecular switches. Summary of the Invention

[0003] In view of this, the present invention provides a bias-responsive switch based on a two-component molecular system, its preparation method and application. The present invention aims to overcome the defects of existing molecular switches, such as single response, poor stability and difficult threshold adjustment, and provides a bias-responsive dual-state molecular switch based on an A and P two-component molecular system. It can achieve precise switching between two conductance states by adjusting the bias amplitude, and has the advantages of stable state, adjustable threshold and simple preparation, which can meet the application requirements of molecular logic circuits and information storage.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: One object of the present invention is to provide a bias-responsive switch based on a two-component molecular system, comprising: a bottom electrode, a bimolecular functional layer, and a top electrode; The double-molecule functional layer is obtained by dissolving A and P components in organic solvents respectively, and then mixing them according to a molar ratio of 1:1. The A component is a non-conjugated compound with a terminal group modified mercapto anchor group, and the HOMO-LUMO energy level gap ΔE is 3.5-4.2 eV; the A component molecule itself can be stably output under a bias voltage of 0.1-0.5 V, and in the A / P mixed system, the electron transmission of the A molecule can be realized by overcoming the energy level barrier under a low bias voltage, which is expressed as a "low resistance state (ON1)"; The P component is a small-molecule compound with a conjugated π electron system, and the HOMO-LUMO energy level gap ΔE is 2.1-2.3 eV; in the A / P mixed system, the P molecule can form a stable electron transmission channel under a high bias voltage, which is expressed as a "high resistance state (ON1)" Preferably, the A component is 1,3-propanedithiol, 1,4-butanedithiol or pentane-1,5-dithiol, which can ensure state stability. The P component is a p-benzenedithiol molecule, which can ensure the formation of a stable charge transmission interface with the electrode.

[0005] Preferably, the bottom electrode is a silicon wafer with an evaporated Au layer, and the thickness is 150 nm. The top electrode is a needle-shaped electrode for STM-BJ, which is made by burning an Au metal needle with a diameter of 0.25 mm into a gold ball.

[0006] Preferably, the organic solvent is anhydrous aprotic solvent, specifically 1,2,4-trichlorobenzene, and the dielectric constant ε is 2.7-2.9, which can ensure the uniform dispersion of the A and P components and avoid response interference caused by chemical interaction (such as hydrogen bond and π-π stacking) between the components.

[0007] Another object of the present application is to provide a preparation method of the bias voltage response type switch based on the double-component molecular system, which comprises the following steps: Step 1: bottom electrode pretreatment The silicon wafer substrate with a silicon dioxide oxidation layer is sequentially cleaned with acetone, anhydrous ethanol and deionized water, and then dried by nitrogen blowing. Then, an Au layer is plated on the surface of the silicon wafer by a plasma sputtering instrument, and then the silicon wafer is placed in a plasma cleaning instrument for a period of time to remove surface adsorbed impurities and oxidation layers, and is ready for use. Step 2: preparation of double-component functional system The A component and the P component are respectively dissolved in an organic solvent to prepare single-component solutions with a concentration of 1 mmol / L, and then mixed according to a molar ratio of 1:1 and ultrasonically treated for 2 min. Step 3: top electrode pretreatment A sphere is formed by burning one end of a gold wire in a butane-mixed flame. Step 4: Construction of the molecular switch The top electrode is reciprocated up and down by the piezoelectric ceramic in the STM-BJ device, continuously contacting the Au layer of the bottom electrode during this process. Then, an A / P mixed solution is dropped onto the Au layer of the bottom electrode. During the gold-gold contact breakage process, the target molecules can connect to the two electrodes in situ, thereby forming an electrode-molecule-electrode molecular junction. By adjusting the applied external bias voltage, the high conductivity state output of different component molecules in the mixed system is achieved, completing the "bias-conductivity" switching construction.

[0008] Preferably, the ultrasonic cleaning before coating in step 1 is performed at 300W for 8-12 minutes.

[0009] Preferably, the plasma cleaner in step 1 uses an Ar atmosphere, a flow rate of 20 sccm, and a treatment time of 5 min.

[0010] Another objective of this invention is to provide the application of the above-mentioned bias-response switch based on a two-component molecular system in threshold voltage regulation, sensors, logic circuits, and analog neuromorphic devices.

[0011] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: (1) Precise switching between two states: In the A1 / P hybrid system, the two conductance states are switched without crossover by the bias voltage amplitude (0.1V activates the ON1 state, >0.1V activates the ON2 state). The conductance value of the ON1 state is 3.2×10 -3 The conductance values ​​of the G0 and ON2 states (1.58 × 10⁻⁶) are also relevant. -2 The ratio of G2 / G1 to G0 is 5; in the A2 / P hybrid system, the two conductance states are switched without crossover by the bias voltage amplitude (0.1-0.3V activates the ON1 state, >0.3V activates the ON2 state), and the conductance value of the ON1 state (1×10) is 5. -3 The conductance values ​​of the G0 and ON2 states (1.58 × 10⁻⁶) are also relevant. -2 The ratio of G2 / G1 to G0 is 15.8; in the A3 / P hybrid system, the two conductance states are switched without crossover by the bias voltage amplitude (0.1-0.4V activates the ON1 state, >0.4V activates the ON2 state), and the conductance value of the ON1 state is (4×10). -4 The conductance values ​​of the G0 and ON2 states (1.58 × 10⁻⁶) are also relevant. -2 The ratio (G2 / G1) of G0 can reach 39.5, indicating high state resolution.

[0012] (2) High stability: Components A and P are strongly coupled to the electrode through thiol anchoring groups, and there is no structural isomerization process. Cycle switching lifetime > 10 4 The state retention time is >100h (25℃, ambient atmosphere), which is far superior to traditional photoinduced isomeric molecular switches; (3) Threshold adjustable: By realizing the customization of the response threshold: by adjusting the number of carbon atoms in component A, the threshold voltage gradually increases by 0.1 V; (4) Multi-scenario adaptation: It can realize the logic conversion of "bias voltage-dual state" (such as 0.1V → logic 0, 0.3V → logic 1), and can also be used as a signal conversion unit of sensor (such as converting pressure and temperature signals into bias voltage, thereby triggering the switching state). Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of a molecular switch implemented using an STM-BJ device. The molecules used are: A1: 1,3-propanedithiol; A2: 1,4-butanedithiol; A3: pentane-1,5-dithiol; P: p-phenylenediol molecule.

[0015] Figure 2 (ae): The one-dimensional conductivity histogram obtained when the external bias voltage is 0.1-0.5V in the mixed system of 1,3-propanedithiol and p-phenylenediol molecules. The high conductivity peak gradually red-shifts with the increase of bias voltage, that is, it changes from the characteristic peak of 1,3-propanedithiol molecules (0.1 V) to the characteristic peak of p-phenylenediol molecules (0.2-0.5 V); f: The one-dimensional conductivity histogram obtained when the external bias voltage is directly reduced from 0.5V to 0.1V. The characteristic peak of the high conductivity state switches from the characteristic peak of p-phenylenediol molecules to the characteristic peak of 1,3-propanedithiol molecules.

[0016] Figure 3 (ae): Two-dimensional conductivity distribution obtained in the mixed system of 1,3-propanedithiol and p-phenylenediol molecules with an external bias voltage of 0.1-0.5 V; f: Two-dimensional conductivity distribution obtained when the external bias voltage is directly reduced from 0.5 V to 0.1 V.

[0017] Figure 4(ae): One-dimensional conductivity histogram obtained when the external bias voltage is 0.1-0.5V in the mixed system of 1,4-butanedithiol and p-phenylenediol molecules. The high conductivity peak gradually red-shifts with the increase of bias voltage, that is, it changes from the characteristic peak of 1,4-butanedithiol molecules (0.1-0.3 V) to the characteristic peak of p-phenylenediol molecules (0.4-0.5 V); f: One-dimensional conductivity histogram obtained when the external bias voltage is directly reduced from 0.5 V to 0.1 V. The characteristic peak of the high conductivity state switches from the characteristic peak of p-phenylenediol molecules to the characteristic peak of 1,4-butanedithiol molecules.

[0018] Figure 5 (ae): Two-dimensional conductivity distribution obtained in the mixed system of 1,4-butanedithiol and p-phenylenediol molecules with an external bias voltage of 0.1-0.5V; f: Two-dimensional conductivity distribution obtained when the external bias voltage is directly reduced from 0.5V to 0.1V. The conclusions are consistent with those obtained from the one-dimensional conductivity histogram.

[0019] Figure 6 (ae): One-dimensional conductivity histogram obtained when the external bias voltage is 0.1-0.5V in the mixed system of pentane-1,5-dithiol and p-phenylenediol molecules. The high conductivity peak gradually red-shifts with the increase of bias voltage, that is, it changes from the characteristic peak of pentane-1,5-dithiol molecules (0.1-0.4 V) to the characteristic peak of p-phenylenediol molecules (0.5 V); f: One-dimensional conductivity histogram obtained when the external bias voltage is directly reduced from 0.5 V to 0.1 V. The characteristic peak of the high conductivity state changes from the characteristic peak of p-phenylenediol molecules to the characteristic peak of pentane-1,5-dithiol molecules.

[0020] Figure 7 (ae): Two-dimensional conductivity distribution obtained in the mixed system of pentane-1,5-dithiol and p-phenylenediol molecules with an external bias voltage of 0.1-0.5 V; f: Two-dimensional conductivity distribution obtained when the external bias voltage is directly reduced from 0.5 V to 0.1 V. The conclusions are consistent with those obtained from the one-dimensional conductivity histogram.

[0021] Figure 8 This is a one-dimensional normalized conductivity histogram of the 1,3-propanedithiol molecule under an external bias of 0.1–0.5 V. The high conductivity peak of the molecule remains unchanged and is not bias-dependent.

[0022] Figure 9 This is a one-dimensional normalized conductivity histogram of the 1,4-butanedithiol molecule under an external bias voltage of 0.1–0.5 V. The high conductivity peak of the molecule remains unchanged and is not bias-dependent.

[0023] Figure 10This is a one-dimensional normalized conductivity histogram of the pentane-1,5-dithiol molecule under an external bias voltage of 0.1–0.5 V. The high conductivity peak of the molecule remains unchanged and is not bias-dependent.

[0024] Figure 11 This is a one-dimensional normalized conductivity histogram of the p-phenylenedithiol molecule under an external bias voltage of 0.1–0.5 V. The high conductivity peak of the molecule remains unchanged and is not bias-dependent. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] Example 1: Preparation and Basic Performance Testing of a Two-State Molecular Switch Component A consists of molecules of 1,3-propanedithiol, 1,4-butanedithiol, and pentane-1,5-dithiol, while component P consists of a molecule of p-phenylenediol. The organic solvent was 1,2,4-trichlorobenzene, with an A to P molar ratio of 1:1 and a concentration of 1 mmol / L for both. Molecular switch structure: bottom electrode (Au layer, 150 nm thick) → functional molecule (droplet, 5 μL volume) → top electrode (Au gold sphere). Performance testing: Using STM-BJ technology, an external bias voltage of 0.1~0.5 V was applied, and the conductance changes were recorded. 0.1~0.5V: The high conductivity states of components A1, A2, and A3 are stable at 3.2×10⁻⁶ V. -3 G 0、 1×10 -3 G 0、 4×10 -4 Around G0, there is no bias dependence; The high conductivity state of the P component molecules is stable at 1.58 × 10⁻⁶. -2 Around G0, there is no bias dependence; At 0.1 V, the high conductivity state of molecules in the A1 / P mixture is at 3.2 × 10⁻⁶ V. -3 Around G0, the characteristic peaks belong to the A1 molecule; at 0.2~0.5V, the high conductivity state of the molecules in the A1 / P mixture is 1.58×10⁻⁶. -2 Around G0, a characteristic peak belonging to the P molecule; When the bias voltage is directly reduced from 0.5 V to 0.1 V, the high conductivity state of the molecules in the A1 / P mixture is at 3.2 × 10⁻⁶.- 3 Around G0, a characteristic peak belonging to the A1 molecule; Loop test: 10 4 After the first switching, the threshold voltage (0.2 V) did not drift.

[0027] Example 2: Threshold voltage regulation and sensor application Regulation method: When component A1 replaces molecule A2, at 0.1 ~ 0.3 V, the high conductivity state of molecules in the A2 / P mixture is 1 × 10⁻⁶. -3 Around G0, the characteristic peaks belong to the A2 molecule; at 0.4~0.5V, the high conductivity state of the molecules in the A2 / P mixture is 1.58×10⁻⁶. -2 Around G0, a characteristic peak belonging to the P molecule; When the bias voltage is directly reduced from 0.5 V to 0.1 V, the high conductivity state of the molecules in the A2 / P mixture is at 1×10⁻⁶. -3 Around G0, a characteristic peak belonging to the A2 molecule; The threshold voltage rose to 0.4V; ②When component A1 replaces molecule A3, at 0.1 ~ 0.4 V, the high conductivity state of molecules in the A2 / P mixture is at 4 × 10⁻⁶. -4 Around G0, the characteristic peaks belong to the A3 molecule; at 0.5 V, the high conductivity state of the molecules in the A2 / P mixture is 1.58 × 10⁻⁶. -2 Around G0, a characteristic peak belonging to the P molecule; When the bias voltage is directly reduced from 0.5 V to 0.1 V, the high conductivity state of the molecules in the A3 / P mixture is at 4 × 10⁻⁶. -4 Around G0, a characteristic peak belonging to the A3 molecule; The threshold voltage rises to 0.5 V. Example 3: Application of molecular switches in logic circuits Based on the dual-state molecular switch of Embodiment 1, it can correspond to the "NOT gate" logic unit: when the input bias is 0.1 V (ON1 state, logic 0), the output is low (0.1 V); when the input bias is 0.2 V (ON2 state, logic 1), the output is high (0.2 V).

[0028] Example 4: Application of molecular switches in analog neuromorphic devices Based on the dual-state molecular switch of Example 1, it can correspond to the biomimetic of neuromorphology: when the input bias voltage is 0.1 V (ON1 state, low threshold activation), the output is a Na⁺ channel-like channel (3.2 × 10⁻⁶). -3 G0); with an input bias of 0.2 V (ON2 state, high threshold activation), the output class K⁺ channel (1.58×10⁻⁶) -2 G0).

[0029] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0030] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A bias-response switch based on a two-component molecular system, characterized in that, include: Bottom electrode, bimolecular functional layer, and top electrode; The bimolecular functional layer is obtained by dissolving components A and P separately in an organic solvent and then mixing them in a 1:1 molar ratio. Component A is a non-conjugated compound with terminal modified thiol anchoring groups, and the HOMO-LUMO energy level gap ΔE = 3.5-4.2 eV; The P component is a small molecule compound with a conjugated π electron system and a HOMO-LUMO energy level gap ΔE = 2.1-2.3 eV.

2. The bias-response switch based on a two-component molecular system according to claim 1, characterized in that, Component A is 1,3-propanedithiol, 1,4-butanedithiol or pentane-1,5-dithiol; The P component is a p-phenylenediol molecule.

3. A bias-response switch based on a two-component molecular system according to claim 1, characterized in that, The bottom electrode is a silicon wafer with a vapor-deposited Au layer, with a thickness of 150 nm; The top electrode is a gold ball made by burning a 0.25 mm Au metal needle tip, which is used as the needle-type electrode of STM-BJ.

4. A bias-response switch based on a two-component molecular system according to claim 1, characterized in that, The organic solvent is 1,2,4-trichlorobenzene, with a solvent dielectric constant ε = 2.7-2.

9.

5. The method for fabricating a bias-responsive switch based on a two-component molecular system as described in any one of claims 1-4, characterized in that, Includes the following steps: Step 1: Bottom Electrode Pretreatment After ultrasonically cleaning the silicon wafer substrate with the silicon dioxide oxide layer in sequence with acetone, anhydrous ethanol, and deionized water and drying it with nitrogen, an Au layer is deposited on the surface of the silicon wafer by plasma sputtering. Then, it is placed in a plasma cleaner for a period of time to remove surface adsorbed impurities and oxide layer, and then set aside for later use. Step 2: Preparation of the two-component functional system Component A and component P were dissolved separately in organic solvents to prepare single-component solutions with a concentration of 1 mmol / L. The solutions were then mixed at a molar ratio of 1:1 and sonicated for 2 min to obtain a mixed solution of A / P. Step 3: Top electrode pretreatment A sphere is formed by burning one end of a gold wire in a butane-mixed flame. Step 4: Construction of the molecular switch The top electrode is reciprocated up and down by the piezoelectric ceramic in the STM-BJ device, continuously contacting the Au layer of the bottom electrode during this process. Then, an A / P mixed solution is dropped onto the Au layer of the bottom electrode. During the gold-gold contact breakage process, the target molecules can connect to the two electrodes in situ, thereby forming an electrode-molecule-electrode molecular junction. By adjusting the applied external bias voltage, the high conductivity state output of different component molecules in the mixed system is achieved, completing the "bias-conductivity" switching construction.

6. The method for fabricating a bias-responsive switch based on a two-component molecular system according to claim 5, characterized in that, The ultrasonic cleaning described in step 1 involves processing at 300W for 8-12 minutes.

7. The method for fabricating a bias-responsive switch based on a two-component molecular system according to claim 5, characterized in that, The plasma cleaner described in step 1 uses an Ar atmosphere, a flow rate of 20 sccm, and a treatment time of 5 minutes.

8. The application of the bias-response switch based on a two-component molecular system as described in any one of claims 1-4 in threshold voltage regulation, sensors, logic circuits, and analog neuromorphic devices.

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