阅读说明：本技术 一种基于双极型半导体的光控人工突触及其制备方法 (Light-operated artificial synapse based on bipolar semiconductor and preparation method thereof ) 是由 周晔 任意 韩素婷 于 2019-08-26 设计创作，主要内容包括：本发明公开了一种基于双极型半导体的光控人工突触及其制备方法,所述基于双极型半导体的光控人工突触包括：半导体层；所述半导体层包括：光致变色化合物和双极型聚合物；其中,所述双极型聚合物的HOMO能级位于开环的光致变色化合物的HOMO能级和闭环的光致变色化合物的HOMO能级之间。通过施加不同波段的光实现了半导体沟道的重构,进而可以实现在相同电压极性下和相同光照波段下沟道导电性的增强或抑制,本发明采用光来重构人工突触,降低了电子突触的能耗,提高了稳定性和重复性,另外,电学端口的缩减有利于操作复杂程度的降低,较好的柔性性能也能实现器件的高机械性。(The invention discloses a light-operated artificial synapse based on a bipolar semiconductor and a preparation method thereof, wherein the light-operated artificial synapse based on the bipolar semiconductor comprises the following components: a semiconductor layer; the semiconductor layer includes: photochromic compounds and bipolar polymers; wherein the HOMO energy level of the bipolar polymer is between the HOMO energy level of the open-ring photochromic compound and the HOMO energy level of the closed-ring photochromic compound. The invention adopts light to reconstruct artificial synapse, reduces the energy consumption of electronic synapse, improves the stability and the repeatability, in addition, the reduction of electrical ports is beneficial to the reduction of the operation complexity, and the high mechanical property of the device can be realized by better flexible performance.)

1. An optically controlled artificial synapse based on a bipolar semiconductor comprising: a semiconductor layer; wherein the semiconductor layer comprises: photochromic compounds and bipolar polymers; wherein the HOMO energy level of the bipolar polymer is between the HOMO energy level of the open-ring photochromic compound and the HOMO energy level of the closed-ring photochromic compound.

2. The ambipolar semiconductor-based optically controlled artificial synapse of claim 1, wherein the difference in the HOMO level of the ambipolar polymer and the HOMO level of the open-loop photochromic compound is less than the difference in the HOMO level of the ambipolar polymer and the HOMO level of the closed-loop photochromic compound.

3. The ambipolar semiconductor-based optically controlled artificial synapse of claim 1, wherein the photochromic compound and the ambipolar polymer are present in a mass ratio of 1: 1-10.

4. The ambipolar semiconductor-based photosynthetically artificial synapse of claim 1, wherein the photochromic compound is one or more of spiropyrans, spirooxazines, spiro oh throat, hexaphenylbismidans, salicylanilides, cytisia indigo-based dyes, azo compounds, fused-ring aromatic compounds, throps, fulgides, diarylethenes.

5. The ambipolar semiconductor-based photosynthetically artificial synapse of claim 4, wherein the diarylethene comprises

The bipolar polymer is one or more of PBIBDF-BT, CNTVT, SVS, PBCDC, PDPP-4FTVT and PDPPPT.

6. The ambipolar semiconductor-based optically controlled artificial synapse of any of claims 1-5, further comprising: the semiconductor device comprises a dielectric layer, a grid electrode and a substrate which are sequentially arranged below the semiconductor layer, and a source electrode and a drain electrode which are arranged above the semiconductor layer.

7. The ambipolar semiconductor-based optically controlled artificial synapse of claim 6, wherein the dielectric layer is an aluminum oxide dielectric layer having an octadecyl trichlorosilane chemisorbed self-assembled monolayer disposed thereon.

8. The bipolar semiconductor-based optically controlled artificial synapse of claim 6, wherein the gate is a silver gate, the source is a gold source, the drain is a gold drain, and the substrate is a PET substrate.

9. A method for preparing the bipolar semiconductor based optically controlled artificial synapse of any one of claims 1-5, comprising:

and mixing the photochromic compound and the bipolar polymer and depositing to form a semiconductor layer.

10. The method for preparing the bipolar semiconductor-based optically controlled artificial synapse of claim 9, wherein the step of mixing the photochromic compound and the bipolar polymer and depositing the mixture to form the semiconductor layer comprises:

respectively dissolving a photochromic compound and a bipolar polymer by using a solvent and then mixing to obtain a mixed solution;

and carrying out annealing treatment after the mixed solution is coated on the dielectric layer in a spin mode to obtain the semiconductor layer.

Technical Field

The invention relates to the field of artificial synapses, in particular to a bipolar semiconductor-based light-operated artificial synapse and a preparation method thereof.

Background

In the nervous system of the human brain, many intelligent functions such as learning and perception are closely related to external environmental stimuli. These stimuli are detected by receptors and then transmitted as electrochemical signals to synapses for further processing. Through this processing of information, we generate specific perceptions of these environmental changes and respond accordingly. In neurons, the presynaptic membrane can release a variety of different excitatory and inhibitory neurotransmitters to cause excitatory and inhibitory post-synaptic membrane potentials, respectively, to effect signal processing and transmission. However, the synaptic response of some synapses is not fixed, and it can be reconstructed between different synaptic responses by a regulatory signal from the central nervous system. Several studies report that some neuromodulators in the nervous system play an important role in this remodeling. For example, endorphins and related opioid receptors in the central nervous system can act as neuromodulators for modulating neural activity in the pain pathway, producing significantly different subjective sensations to the same noxious stimuli (e.g., extreme temperatures, mechanical stress), and this endogenous modulation is believed to be the basis for modulating pain perception in biological systems. Due to this adjustable tactile perception in the nervous system, we can accurately sense and respond appropriately to external environmental changes. Therefore, to implement such a perceptually tunable artificial intelligence system, it is important to construct an artificial synapse with a reconfigurable synaptic response.

Hardware implementation of artificial synapses with complex synaptic functions remains a considerable challenge. In the prior art, a neuromorphic circuit based on Complementary Metal-Oxide Semiconductor (CMOS) technology needs a plurality of transistors to simulate a synapse, thereby greatly increasing the system complexity and raising the problem of scalability. Therefore, some research teams have focused on building artificial synapse devices based on memristors or transistors. Although a single device may mimic some specific synaptic function, none of these artificial synapses dynamically reconstructs the response of the synapse. In recent years, two-dimensional materials have attracted much attention as alternatives to conventional semiconductors due to their special material properties (e.g., atomic scalability). Some research teams have fabricated artificial synapses based on two-dimensional materials to mimic some specific synaptic responses, and some of these devices are also capable of dynamically reconstructing synaptic responses. However, reconfiguration in these devices is achieved by adding additional control ports, such as additional gates for modulating the channel, adjustable bias ports, synergy of the electro/ionic/photo-active gates, etc., which increase the complexity and operational inconvenience of device fabrication and cause higher power consumption, and the interaction of multiple ports inevitably affects the stability and repeatability of the device.

Accordingly, the prior art is yet to be improved and developed.

Disclosure of Invention

The invention aims to solve the technical problem of providing a bipolar semiconductor-based light-operated artificial synapse and a preparation method thereof, aiming at solving the problem of low stability and repeatability of the artificial synapse in the prior art.

The technical scheme adopted by the invention for solving the technical problem is as follows:

an optically controlled artificial synapse based on a bipolar semiconductor comprising: a semiconductor layer; wherein the semiconductor layer includes: photochromic compounds and bipolar polymers; wherein the HOMO energy level of the bipolar polymer is between the HOMO energy level of the open-ring photochromic compound and the HOMO energy level of the closed-ring photochromic compound.

The light-operated artificial synapse based on the bipolar semiconductor is characterized in that the difference value between the HOMO energy level of the bipolar polymer and the HOMO energy level of the open-loop photochromic compound is smaller than the difference value between the HOMO energy level of the bipolar polymer and the HOMO energy level of the closed-loop photochromic compound.

The light-operated artificial synapse based on the bipolar semiconductor is characterized in that the mass ratio of the photochromic compound to the bipolar polymer is 1: 1-10.

The light-operated artificial synapse based on the bipolar semiconductor is characterized in that the photochromic compound is one or more of spiropyran, spirooxazine, spiro oh throat, hexaphenylbismidan, salicyloaldolase compounds, Zhou cai indigo dyes, azo compounds, condensed ring aromatic compounds, throps, fulgides and diarylethenes.

The light-operated artificial synapse based on the bipolar semiconductor is characterized in that the diarylethene comprises

The bipolar polymer is one or more of PBIBDF-BT, CNTVT, SVS, PBCDC, PDPP-4FTVT and PDPPPT.

The light-operated artificial synapse based on the bipolar semiconductor further comprises: the semiconductor device comprises a dielectric layer, a grid electrode and a substrate which are sequentially arranged below the semiconductor layer, and a source electrode and a drain electrode which are arranged above the semiconductor layer.

The light-operated artificial synapse based on the bipolar semiconductor is characterized in that the dielectric layer is an aluminum oxide dielectric layer, and an octadecyl trichlorosilane chemical adsorption self-assembly monomolecular layer is arranged on the aluminum oxide dielectric layer.

The light-operated artificial synapse based on the bipolar semiconductor is characterized in that the gate is a silver gate, the source electrode is a gold source electrode, the drain electrode is a gold drain electrode, and the substrate is a PET substrate.

A preparation method of the bipolar semiconductor-based optically controlled artificial synapse comprises the following steps:

and mixing the photochromic compound and the bipolar polymer and depositing to form a semiconductor layer.

The preparation method of the light-operated artificial synapse based on the bipolar semiconductor comprises the following steps of mixing a photochromic compound and a bipolar polymer and depositing to form a semiconductor layer:

respectively dissolving a photochromic compound and a bipolar polymer by using a solvent and then mixing to obtain a mixed solution;

and carrying out annealing treatment after the mixed solution is coated on the dielectric layer in a spin mode to obtain the semiconductor layer.

Has the advantages that: the invention adopts light to reconstruct artificial synapse, reduces the energy consumption of electronic synapse, improves the stability and the repeatability, in addition, the reduction of electrical ports is beneficial to the reduction of the operation complexity, and the high mechanical property of the device can be realized by better flexible performance.

Drawings

FIG. 1 is a schematic diagram of the bipolar semiconductor-based optically controlled artificial synapse in accordance with the present invention.

FIG. 2 is a schematic structural diagram of a bipolar semiconductor-based optically controlled artificial synapse in accordance with the present invention.

FIG. 3A is a graph of a first electrical characteristic of a bipolar semiconductor-based synapse transistor in accordance with the present invention.

FIG. 3B is a graph of a second electrical characteristic of a bipolar semiconductor-based synapse transistor in accordance with the present invention.

FIG. 4A is a graph of a third electrical characteristic of a bipolar semiconductor-based synapse transistor in accordance with the present invention.

FIG. 4B is a graph of a fourth electrical characteristic of a bipolar semiconductor-based synapse transistor in accordance with the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer and clearer, the present invention is further described in detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Referring to fig. 1-4, the present invention provides some embodiments of a bipolar semiconductor-based optically controlled artificial synapse. Fig. 3 includes fig. 3A and 3B, and fig. 4 includes fig. 4A and 4B.

As shown in fig. 2, an optically controlled artificial synapse based on a bipolar semiconductor of the present invention comprises: a semiconductor layer; the semiconductor layer includes: photochromic compounds and bipolar polymers; wherein the HOMO energy level of the bipolar polymer is between the HOMO energy level of the open-ring photochromic compound and the HOMO energy level of the closed-ring photochromic compound.

It is worth noting that the artificial synapse in the present invention is presented in the form of a transistor, including: the semiconductor device comprises a substrate, a grid, a dielectric layer, a semiconductor layer, a source electrode and a drain electrode, wherein the substrate, the grid, the dielectric layer and the semiconductor layer are arranged in sequence, and the source electrode and the drain electrode are arranged on the semiconductor layer. The dielectric layer is an alumina dielectric layer, and an Octadecyl Trichlorosilane (OTS) chemical adsorption self-assembly monolayer is arranged on the alumina dielectric layer. The grid is a silver grid, the source electrode is a gold source electrode, the drain electrode is a gold drain electrode, and the substrate is a PET substrate. Gold source/drain electrodes (channel length/width: 30 microns/1000 microns) will be deposited on the semiconductor thin film by a reticle.

The semiconductor layer comprises two substances, namely a photochromic compound and a bipolar polymer, wherein the photochromic compound is in two states of open loop or closed loop due to configuration transformation under the irradiation of ultraviolet light, when the photochromic compound is in two different states, the LUMO (lowest unoccupied Molecular Orbital) energy level and the HOMO (Highest Occupied Molecular Orbital) energy level are different, and E is respectively used_{H-shaped opener}And E_{H is closed}Indicating the HOMO level of the open-ring photochromic compound and the HOMO level of the closed-ring photochromic compound, whereas the HOMO level adopted in the present invention is located at E_{H-shaped opener}And E_{H is closed}With a bipolar polymer of E_{H poly}Which represents the HOMO level of the bipolar polymer.

As shown in FIG. 1, E_HOMOThe HOMO level is expressed in eV. E_{H is closed}>E_{H-shaped opener}When HOMO_{Poly(s) are polymerized}At E_{H-shaped opener}And E_{H is closed}In between, the open-loop state is the normal state, and in the normal state, E_{H-shaped opener}<E_{H poly}Holes of the bipolar polymer cannot be trapped, and the semiconductor channel is p-type. When a synaptic transistor (or photochromic compound) is irradiated by ultraviolet light, the photochromic compound changes from an open-loop state to a closed-loop state, and the HOMO energy level is increased to become E_{H is closed}A deep level trap potential well for holes is formed, causing the semiconductor channel to assume an n-type. By applying visible light (green light) to the synaptic transistor, the photochromic compound returns from the closed-loop state to the original open-loop state, the HOMO level decreases, the photochromic compound releases the trapped holes, and the semiconductor channel assumes p-type. The invention adopts light to reconstruct artificial synapse, reduces the energy consumption of electronic synapse, improves the stability and the repeatability, in addition, the reduction of electrical ports is beneficial to the reduction of the operation complexity, and the high mechanical property of the device can be realized by better flexible performance.

Specifically, as shown in FIG. 3A, a positive voltage (V) is applied to the gate_GSGate voltage) in an initial state, the device is in an n-type channel; when the photochromic compound is irradiated by ultraviolet light, the photochromic compound is changed into a closed ring state from an open ring state, the HOMO energy level is increased, holes in a channel are captured by the photochromic compound, and therefore n-state current is increased and p-state current is reduced.

Then, as shown in fig. 3B, the gate is still applied with positive voltage, the device is in an n-type channel in the initial state, and when the device is irradiated by green light, the photochromic compound changes from a closed-loop state to an open-loop state, the HOMO energy level decreases, and holes trapped by the photochromic compound are released back to the channel again, so that the n-state current decreases and the p-state current increases.

As shown in fig. 4A, the gate is applied with negative voltage, and in the initial state, the device is in the p-type channel; when the photochromic compound is irradiated by ultraviolet light, the photochromic compound is changed into a closed ring state from an open ring state, the HOMO energy level is increased, holes in a channel are captured by the photochromic compound, and therefore n-state current is increased and p-state current is reduced.

Then, as shown in fig. 4B, the gate is applied with a negative voltage, the device is in a p-type channel in the initial state, and when the device is irradiated by green light, the photochromic compound changes from a closed-loop state to an open-loop state, the HOMO energy level decreases, and holes trapped by the photochromic compound are released back to the channel again, so that the n-state current decreases and the p-state current increases.

Since the light application time is not long and the amount of trapped holes is insufficient, the line bulk migration is exhibited, but in other embodiments, the light application time is extended, and channel deflection can be obtained, i.e., the p-type channel is converted into the n-type channel, or the n-type channel is converted into the p-type channel.

The semiconductor layer of the invention is prepared by the following steps:

and S100, mixing the photochromic compound and the bipolar polymer, and depositing to form a semiconductor layer.

The photochromic compound and the bipolar polymer are compounded to form the semiconductor layer in a mixing mode, and the semiconductor layer can be formed in a deposition mode, a spin coating mode, an ink jet mode and the like.

Specifically, step S100 includes:

and step S110, respectively dissolving the photochromic compound and the bipolar polymer by using a solvent, and then mixing to obtain a mixed solution.

The solvent is selected according to the photochromic compound and the bipolar polymer, such as chlorobenzene. The two substances can be selected from the same solvent or different solvents.

And step S120, carrying out annealing treatment after the mixed solution is coated on the dielectric layer in a spinning mode to obtain the semiconductor layer.

The semiconductor layer is disposed on the dielectric layer so that the mixture is spin coated on the dielectric layer, and when other types of devices are used, the semiconductor layer may be spin coated on other functional layers. The temperature of the annealing treatment is 100-140 ℃, and the annealing time is 10-30 minutes. The semiconductor layer is prepared by a simple solution method, so that the preparation process is simplified, and the preparation cost is reduced.

In a preferred embodiment of the present invention, as shown in fig. 1, the difference between the HOMO level of the bipolar polymer and the HOMO level of the open-ring photochromic compound is smaller than the difference between the HOMO level of the bipolar polymer and the HOMO level of the closed-ring photochromic compound.

That is, E_{H poly}Is closer to E_{H-shaped opener}And is away from E_{H is closed}And furthermore, the closed-loop photochromic compound has a deep energy level trapping potential well for holes in the bipolar polymer, so that the holes are easier to trap, and the enhancement and inhibition effects of light control are improved.

In a preferred embodiment of the invention, the mass ratio of the photochromic compound to the bipolar polymer is 1: 1-10.

Specifically, the mass ratio of the photochromic compound to the bipolar polymer is set according to the types of the photochromic compound and the bipolar polymer, and the stability and the light control performance of the semiconductor layer are different under different mass ratios. In the invention, DAE molecules are selected as photochromic compounds, PBIBDF-BT is selected as a bipolar polymer, and the structural formula of DAE is shown in the specification

The structural formula of PBIBDF-BT is shown in the specification

As shown in FIG. 1, the HOMO energy level of DAE is E_{H-shaped opener}＝-5.59eV，E_{H is closed}HOMO energy level of PBIBDF-BT of-4.79 eV_{H poly}HOMO level E of PBIBDF-BT ═ 5.55eV_{H poly}HOMO energy level E at DAE_{H-shaped opener}、E_{H is closed}E between, and near the DAE_{H-shaped opener}. The quality ratio of PBIBDF-BT to DAE is 1:3, the formed semiconductor layer has high stability and quick response.

In a preferred embodiment of the invention, the photochromic compound is one or more of spiropyran, spirooxazine, spiro oh throat, hexaphenylbismidan, salicylanilide compounds, zoa indigoid dyes, azo compounds, fused ring aromatic compounds, blepharos, fulgides, diarylethenes.

In particular, the diarylethenes include DAE, but may of course also be other diarylethenes. The bipolar polymer is one or more of PBIBDF-BT, CNTVT, SVS, PBCDC, PDPP-4FTVT and PDPPTPPT.

The structural formula of CNTVT and SVS is

PBCDC has the structural formula

The structural formula of PDPP-4FTVT is

The structural formula of PDPPTPT is

The synapse transistor of the invention has the following effects:

(1) compared with the traditional reconfigurable pure electric synapse, the reconfigurable pure electric synapse introduces light to reconstruct a semiconductor channel, realizes the enhancement and the inhibition of a conducting channel under the same voltage polarity (an electrical mode) and the same illumination wave band (an optical mode), simplifies the preparation process of a device, and greatly reduces the power consumption of the device.

(2) The continuous stimulation of nanosecond-level light pulses can maintain the continuous change of the conductivity of the device, and realize the multi-level change of the device and the linear modulation of the conductance.

(3) The synapse transistor is prepared by a simple solution method and is easy to print, the energy consumption of photoetching patterning and a vacuum preparation method is greatly reduced, and meanwhile, the high mechanical property of the device can be realized due to the good flexibility of the device.

The present invention further provides a preferred embodiment of the method for preparing the bipolar semiconductor-based optically controlled artificial synapse according to any of the above embodiments:

the embodiment of the invention provides a preparation method of a bipolar semiconductor-based optically controlled artificial synapse, which comprises the following steps:

and S100, mixing the photochromic compound and the bipolar polymer, and depositing to form a semiconductor layer.

Specifically, the step S100 specifically includes:

and step S110, respectively dissolving the photochromic compound and the bipolar polymer by using a solvent, and then mixing to obtain a mixed solution, which is specifically described above.

Step S120, spin-coating the mixed solution on the dielectric layer, and then annealing to obtain the semiconductor layer, as described above.

In summary, the light-operated artificial synapse based on a bipolar semiconductor and the method for manufacturing the same provided by the present invention include: a semiconductor layer; the semiconductor layer includes: photochromic compounds and bipolar polymers; wherein the HOMO energy level of the bipolar polymer is between the HOMO energy level of the open-ring photochromic compound and the HOMO energy level of the closed-ring photochromic compound. The invention adopts light to reconstruct artificial synapse, reduces the energy consumption of electronic synapse, improves the stability and the repeatability, in addition, the reduction of electrical ports is beneficial to the reduction of the operation complexity, and the high mechanical property of the device can be realized by better flexible performance.

It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.