Bias voltage regulated MoS2 / PbS heterojunction photoelectric device

Abstract

The invention belongs to the technical field of photoelectric devices, and discloses a bias voltage regulated MoS2 / PbS heterojunction photoelectric device, which is characterized in that FTO glass is used as a conductive substrate, a MoS2 film and a PbS film are sequentially grown on the surface of the FTO glass, the PbS film forms a three-dimensional skeleton coating type structure for MoS2, and two Ag electrodes are deposited on the PbS film and the FTO glass. The photoelectric device disclosed by the invention integrally realizes two performances of neuromorphic photoelectric synapse and broadband photoelectric detection; the synapse characteristic of the device comes from modulation of interface defects, and advanced synapse functions such as short and long term memory conversion (STM / LTM), repeated learning and forgetting and the like of light regulation are realized; the excellent detection performance of the device comes from rapid separation of heterogeneous interface carriers. The preparation process of the photoelectric device is simple, the large-area film can be suitable for industrial production, and development in the fields of simulation of human optic nerve memory and detection from ultraviolet to short wave infrared bands is expanded.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic devices, and in particular relates to a bias-controlled MoS2 / PbS heterojunction optoelectronic device. Background Art

[0002] Against the backdrop of the rapid development of artificial intelligence (AI), the development of optoelectronic devices into intelligent systems that can integrate perception, memory, and computing has become imperative. Modern advanced technologies, including intelligent medical equipment, robotics, space, and other fields, require not only multi-spectral optical signal acquisition from ultraviolet (UV) to near-infrared (NIR) wavelengths, but also adaptive information processing capabilities similar to biological sensory neurons. Computers are very similar to the human brain. Humans use the visual system to perceive and identify external light, and then quickly transmit it to the brain through synapses for rapid processing. Therefore, artificial synapses made by simulating biological synapses can integrate computing and memory functions, thereby breaking through the von Neumann bottleneck of traditional computers.

[0003] MoS2 in transition metal chalcogenides (TMDCs) has become a popular choice for optoelectronic devices due to its atomic-scale thickness-tunable band gap (1.2-1.8 eV) and special light interactions. However, the band gap limitation of MoS2 itself leads to its insufficient response to near-infrared (NIR, 800-2000 nm) light. Therefore, through heterojunction engineering and combining with materials with high response to the near-infrared band, such as Si, PbS, etc., the device can be expanded to night vision, lidar and other fields. However, the complex preparation process of heterojunctions, and the limited contact area and limited light absorption of traditional planar heterojunctions, have led to the fact that most of the reported devices have low light response and slow speed in the detection field, poor retention characteristics and high power consumption in the synaptic field, and the functions achieved are single. Due to the contradiction in light response speed, traditional synaptic devices cannot be integrated with detection devices, so it is urgent to realize the simple preparation and functional integration of optical devices. Summary of the invention

[0004] Based on the above-mentioned deficiencies in the prior art, the present invention provides a bias-regulated MoS2 / PbS heterojunction optoelectronic device, explores the basic artificial synaptic functions and excellent detection performance achieved under different bias voltages, provides a simple and efficient way to improve the performance of optoelectronic devices, and solves the problem that it is impossible to integrate optoelectronic synapse and detection functions in a single device.

[0005] In order to achieve the purpose, the present invention adopts the following technical scheme: A bias-regulated MoS2 / PbS heterojunction optoelectronic device is characterized in that it is a vertically structured two-terminal device, with FTO glass as a conductive substrate, a MoS2 film with a nano-flower ball morphology grown on the surface of the FTO glass by a hydrothermal method, a PbS film grown on the MoS2 film by a water bath method, and the PbS film forms a three-dimensional skeleton-coated structure for the MoS2; a first Ag electrode is arranged on the PbS film, and a second Ag electrode is arranged in an area of ​​the FTO glass where the MoS2 film and the PbS film are not grown.

[0006] The MoS2 / PbS heterojunction optoelectronic device of the present invention realizes two properties of neuromorphic optoelectronic synapse and broadband optoelectronic detection through integration. The synaptic properties of the device come from the modulation of interface defects, and realize advanced synaptic functions such as light-regulated short-term memory conversion (STM / LTM) and repeated learning and forgetting. The excellent detection performance of the device comes from the rapid separation of heterogeneous interface carriers. Specifically, by adjusting the bias voltage applied to the two Ag electrodes and irradiating light from ultraviolet to short-wave infrared bands (wavelength range of 405-1650 nm), the two optoelectronic properties of the MoS2 / PbS heterojunction optoelectronic device are regulated: under 0V bias, the MoS2 / PbS heterojunction optoelectronic device realizes broadband optoelectronic detection; as the bias voltage increases, the optoelectronic synaptic performance of the MoS2 / PbS heterojunction optoelectronic device gradually increases.

[0007] The present invention further discloses a method for preparing the bias-regulated MoS2 / PbS heterojunction optoelectronic device, comprising the following steps: Step 1: Ultrasonic clean the FTO glass with acetone, ethanol and deionized water in sequence to remove surface impurities, and then blow dry with nitrogen.

[0008] Step 2: Add 0.09 g sodium molybdate and 0.18 g thiourea to 60 mL deionized water and stir evenly, then transfer to a reactor, add the cleaned FTO glass to the reactor, and react at 200 °C for 20-24 h. After the reaction, take out the sample, wash it alternately with deionized water and anhydrous ethanol, and then dry it in an oven at 40-60 °C for 1-2 h to obtain a MoS2 film with a nanoflower morphology.

[0009] Step 3, add 9.475 g of lead acetate to 100 mL of deionized water and stir until completely dissolved to obtain a lead acetate solution; dissolve 14.7 g of trisodium citrate, 5.71 g of thiourea and 7.84 g of potassium hydroxide in 50 mL of deionized water respectively to obtain a trisodium citrate solution, a thiourea solution and a potassium hydroxide solution; vertically suspend the FTO glass with the MoS2 film grown in the lead acetate solution, then add the trisodium citrate solution, the thiourea solution and the potassium hydroxide solution in turn and stir evenly, then place in a 40°C water bath to react for 10 to 20 min; after the reaction is completed, take out the sample and wash it alternately with deionized water and anhydrous ethanol, then place it in an oven at 40 to 60°C and dry it for 1 to 2 h to obtain a PbS film; Step 4: Scrape off the MoS2 film and PbS film on part of the surface of the FTO glass to expose the FTO conductive layer; then deposit a first Ag electrode on the PbS film, and deposit a second Ag electrode on the area of ​​the FTO glass where the MoS2 film and PbS film are not grown, thereby completing the preparation of the MoS2 / PbS heterojunction photoelectric device.

[0010] The beneficial effects of the present invention are embodied in: 1. In the MoS2 / PbS heterojunction optoelectronic device structure of the present invention, the PbS film and the MoS2 film form a high-quality van der Waals heterojunction. The special nano-flower ball morphology of MoS2 provides a rich active interface, greatly increases the contact area, and allows the PbS film to form a three-dimensional skeleton-coated structure during growth. This structure enhances the absorption of incident light through multipath scattering and increases the light response capability of photodetection. Under a bias of 0 V, due to the built-in electric field formed by the heterojunction, the carriers can be quickly separated, which improves the light response speed. After increasing the bias to 0.4 V, the large contact area has more defects, and the potential barrier of the heterojunction becomes higher as the bias increases, resulting in a stronger continuous photoconductivity effect (PPC effect), thereby improving the synaptic performance of the device. Therefore, the MoS2 / PbS heterojunction optoelectronic device of the present invention realizes the integration of photodetection and artificial synaptic performance.

[0011] 2. The MoS2 / PbS heterojunction optoelectronic device of the present invention is prepared by all-liquid phase low-temperature method, which has a simple process flow and greatly saves the preparation cost.

[0012] 3. The photoelectric performance test was carried out by Keithley 4200 instrument. The MoS2 / PbS heterojunction photoelectric device of the present invention achieved high-level synaptic functions such as short-term plasticity, long-term plasticity, transition from short-term memory to long-term memory, repeated learning and forgetting by applying light pulses of different frequencies under 0.4 V bias, and the double pulse facilitation index (PPF index) was as high as 171.6%. Under 0 V bias, by applying light in the range of 405-1650 nm, photoelectric detection from ultraviolet to short-wave infrared was achieved, and the maximum responsivity (0.013 A·W) was achieved at 980 nm. -1 ), specific detection rate (7.6×10 10 Jones) and ultra-fast response speed (rise / decay times of 360 / 351 µs). BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a schematic structural diagram of the MoS2 / PbS heterojunction photoelectric device provided by the present invention.

[0014] Figure 2 (a) and (b) are respectively the scanning electron microscope (SEM) surface image and SEM cross-sectional image of the MoS2 film with nano-flower ball morphology obtained in step 2 of Example 1.

[0015] Figure 3 This is the SEM surface image of the MoS2 / PbS heterojunction photoelectric device prepared in Example 1.

[0016] Figure 4 This is a cross-sectional view of the MoS2 / PbS heterojunction prepared in Example 1 ( Figure 4 (a) in the figure and the energy spectrum of the corresponding elements, where (b) corresponds to the Pb element, (c) corresponds to the S element, and (d) corresponds to the Mo element.

[0017] Figure 5 This is the X-ray diffraction (XRD) pattern of the MoS2 / PbS heterojunction prepared in Example 1.

[0018] Figure 6 The MoS2 / PbS heterojunction prepared in Example 1 ( Figure 6 (a)) and the absorption spectrum of MoS2 film ( Figure 6 (b) in the figure.

[0019] Figure 7 The photoresponse current diagram of the MoS2 / PbS heterojunction optoelectronic device in Example 1 at different bias voltages (0 V, 0.01 V, 0.1 V, 0.2 V, 0.4 V) is shown in Figure 1. The wavelength of the irradiated light is 980 nm and the power is 42.7 mW·cm -2 .

[0020] Figure 8 The double pulse current diagram of the MoS2 / PbS heterojunction optoelectronic device in Example 1 under 980 nm pulse light (bias voltage of 0.4 V) Figure 8 (a)) and the double pulse facilitation (PPF) function diagram ( Figure 8 (b) in the figure.

[0021] Fig. 9 The MoS2 / PbS heterojunction optoelectronic device in Example 1 at different frequencies ( Fig. 9 (a)) and different irradiation durations ( Fig. 9 (b) The photoresponse current diagram of the irradiation light is 980 nm in wavelength and 42.7 mW cm -2 .

[0022] Fig.10 This is a photoresponse current diagram of the MoS2 / PbS heterojunction optoelectronic device in Example 1 under irradiation with 980 nm pulse light (bias voltage of 0.4 V) to simulate repeated learning and forgetting functions.

[0023] Fig.11 (a) is the circuit diagram of the AND and OR gates of the MoS2 / PbS heterojunction optoelectronic device in Example 1, and (b) is the circuit diagram of the AND and OR gates of the MoS2 / PbS heterojunction optoelectronic device at different optical powers (31.5 mW·cm -2 , 42.7 mW·cm -2 ) is the spike pulse current diagram under 980 nm and 650 nm light irradiation, (c) is the logical truth table of the "AND" and "OR" gates, and (d) is the relationship between the "AND" and "OR" gates regarding the spike pulse current.

[0024] Fig.12 The MoS2 / PbS heterojunction photoelectric device in Example 1 at 42.7 mW·cm -2 Voltage-current diagram under 405-1650 nm light irradiation.

[0025] Fig.13 The MoS2 / PbS heterojunction photoelectric device in Example 1 at 42.7 mW·cm -2 Figure 2. Photoresponse current diagram of the 405-1650 nm light irradiation.

[0026] Fig.14 The MoS2 / PbS heterojunction photoelectric device in Example 1 at 42.7 mW·cm -2 1 kHz frequency graph under irradiation with 980 nm light (0V) with a power of 0.

[0027] Fig.15The MoS2 / PbS heterojunction photoelectric device in Example 2 at 42.7 mW·cm -2 Figure 2. Photoresponse current diagram of the 405-1650 nm light irradiation. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. The accompanying drawings provide detailed descriptions of the features and performances of the embodiments. However, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] Example 1 like Figure 1 As shown, this embodiment provides a bias-regulated MoS2 / PbS heterojunction optoelectronic device, which is a vertical structure two-terminal device, using FTO glass as a conductive substrate, a MoS2 film with a nano-flower ball morphology is grown on the surface of the FTO glass by a hydrothermal method, a PbS film is grown on the MoS2 film by a water bath method, and the PbS film forms a three-dimensional skeleton coating structure for the MoS2; a first Ag electrode is arranged on the PbS film, and a second Ag electrode is arranged in the area of ​​the FTO glass where the MoS2 film and the PbS film are not grown.

[0030] This embodiment prepares a bias-controlled MoS2 / PbS heterojunction optoelectronic device according to the following steps: Step 1: Ultrasonic clean the FTO glass with acetone, ethanol and deionized water for 20 min in sequence to remove surface impurities, and then blow dry with nitrogen (purity of more than 99.5%) for later use.

[0031] Step 2: Add 0.09 g sodium molybdate (purity AR 99.0%) and 0.18 g thiourea (purity AR 99.0%) to 60 mL deionized water and stir evenly, then transfer to a 100 mL Teflon-lined reactor, add the cleaned FTO glass to the reactor, and react at 200 °C for 21 h; after the reaction, take out the sample, wash it alternately with deionized water and anhydrous ethanol to remove any residual reactants, and then dry it in an oven at 60 °C for 2 h to obtain a MoS2 film with a nanoflower morphology.

[0032] Step 3, add 9.475 g of lead acetate (purity AR 99.5%) to 100 mL of deionized water and stir until completely dissolved to obtain a lead acetate solution; dissolve 14.7 g of trisodium citrate (purity AR 99.0%), 5.71 g of thiourea (purity AR 99.0%) and 7.84 g of potassium hydroxide (purity AR 90.0%) in 50 mL of deionized water, respectively, to obtain a trisodium citrate solution, a thiourea solution and a potassium hydroxide solution; vertically suspend the FTO glass with the MoS2 film grown in the lead acetate solution, then add the trisodium citrate solution, the thiourea solution and the potassium hydroxide solution in turn and stir evenly, then place it in a 40°C water bath and let it react for 20 min; after the reaction, take out the sample and wash it alternately with deionized water and anhydrous ethanol, then put it in a 60°C oven and dry it for 2 h to obtain a PbS film and form a MoS2 / PbS heterojunction.

[0033] Step 4: Scrape off the MoS2 film and PbS film on part of the surface of the FTO glass to expose the FTO conductive layer; then deposit a first Ag electrode on the PbS film, and deposit a second Ag electrode on the area of ​​the FTO glass where the MoS2 film and PbS film are not grown, thereby completing the preparation of the MoS2 / PbS heterojunction photoelectric device.

[0034] The MoS2 / PbS heterojunction optoelectronic device prepared in the above embodiment was subjected to XRD test using Cu target Kα ray, morphology test using JSM-7001F scanning electron microscope, and optical performance test using Keithley 4200 test system. The specific results are analyzed as follows in conjunction with the accompanying drawings: Figure 2 (a) and (b) are the SEM surface image and SEM cross-sectional image of the MoS2 film obtained in step 2 of this embodiment, respectively. It can be seen that the special nano-flower sphere morphology of MoS2 provides a rich active interface and greatly increases the contact area.

[0035] Figure 3 and Figure 4 (a) in the figure are respectively the SEM surface image and SEM cross-sectional image of the MoS2 / PbS heterojunction prepared in step 3 of this embodiment. It can be seen that the obtained MoS2 / PbS heterojunction has a unique semi-enclosed skeleton-coated hierarchical heterojunction interface structure, which enhances the absorption of incident light through multi-path scattering and increases the light response capability of photoelectric detection. At the same time, the large contact area increases the defects of the interface and enhances the photoelectric synapse performance. Figure 4 (b~d) are the energy spectra corresponding to the cross-section of the MoS2 / PbS heterojunction, where (b) corresponds to the Pb element, (c) corresponds to the S element, and (d) corresponds to the Mo element. It can be seen from the figure that a heterojunction with good contact was obtained.

[0036] Figure 5 This is the X-ray diffraction (XRD) diagram of the MoS2 / PbS heterojunction prepared in step 3 of this embodiment. It can be seen that except for some peaks coming from the FTO glass substrate, most of the peaks are well aligned with the standard diffraction card of lead sulfide (5-0592). Specifically, peaks such as (111), (200), (220), (311) and (400) are clearly visible, indicating the successful preparation of the PbS film. The fact that no peaks related to MoS2 are observed is attributed to the growth of PbS encapsulation on the surface, resulting in the diffraction peak intensity of MoS2 being very weak compared to PbS.

[0037] Figure 6 (a) and (b) are the absorption spectra of the MoS2 / PbS heterojunction and MoS2 film in this embodiment, respectively. It can be seen that compared with the limited absorption range of MoS2 film in ultraviolet and visible light, the absorption of MoS2 / PbS heterojunction is extended to the short-wave infrared range, enhancing the light response capability to short-wave infrared.

[0038] Figure 7 The photoresponse current diagram of the MoS2 / PbS heterojunction optoelectronic device in this embodiment at different bias voltages (0 V, 0.01 V, 0.1 V, 0.2 V, 0.4 V) is shown in Figure 1. The wavelength of the irradiated light is 980 nm and the power is 42.7 mW·cm -2 .from Figure 7 It can be seen that the device exhibits a fast light response speed under a bias voltage of 0 V, because the photogenerated carriers are quickly separated by the built-in electric field; however, as the bias voltage increases, the trend of current decay after the light is turned off slows down as the voltage increases. Because after increasing the bias voltage, the potential barrier of the heterojunction increases, the defects of the heterojunction increase, and the recombination of carriers is limited, the photocurrent of the device gradually tends to stabilize in the PPC state. Therefore, the device of this embodiment can change the photoelectric performance by adjusting the bias voltage, and realize the integration of photoelectric detection and photoelectric synapse on a single device.

[0039] Figure 8 (a) and (b) are respectively a double pulse current diagram and a double pulse facilitation (PPF) function diagram of the MoS2 / PbS heterojunction optoelectronic device of this embodiment under 980 nm pulse light (bias voltage of 0.4 V). Figure 8 (a) shows that under the condition of bias voltage of 0.4 V, two optical powers of 42.7 mW·cm are applied to the PbS / MoS2 heterojunction device. -2 The device successfully simulated the characteristics of double-pulse facilitated PPF by using a pulse with a light exposure time of 150 ms, indicating that the device can simulate the short-term plasticity of synapses. Figure 8As shown in (b), due to the carrier relaxation phenomenon, the PPF index decays with the increase of the interval time between the two pulse lights. When the interval time is 0.1 s, the maximum double-pulse facilitated PPF index of 171.6% is reached.

[0040] Fig. 9 (a) and (b) are the photoresponse current diagrams of the MoS2 / PbS heterojunction optoelectronic device of this embodiment at different frequencies (0.1 Hz, 0.5 Hz, 1 Hz, 2 Hz, 4 Hz) and different irradiation times (1 s, 5 s, 15 s, 30 s), respectively. The wavelength of the irradiated light is 980 nm and the power is 42.7 mW·cm -2 . It can be seen that by increasing the frequency of light pulses (0.1 Hz-4 Hz) or extending the irradiation time (1 s, 5 s, 15 s, 30 s), the photocurrent is enhanced, and the trend of current decay after turning off the light is slowed down, achieving the transition from short-term plasticity to long-term synaptic plasticity. The phenomenon that the connection strength of biological synapses can be enhanced by repeated external stimulation indicates that the device in this embodiment can simulate the short-term and long-term memory conversion function of biological visual neural synapses.

[0041] Fig.10 This is a photoresponse current diagram of the simulated repeated learning and forgetting function of the MoS2 / PbS heterojunction optoelectronic device in this embodiment under 980 nm pulse light (bias 0.4 V). The figure shows three cycles of the learning-forgetting process in synaptic plasticity by continuously turning the light on and off. After 43 consecutive pulses of 980 nm light were continuously excited, the conductance response of the device gradually increased from 204 µA to 214 µA, and then decayed to 206.8 µA after a period of light pulse stimulation, indicating that the learning information will be partially forgotten over time. However, when relearning using the second stimulation process, the current only needs 26 pulses to return to the original learning level (214 µA), which is much lower than the number required for the first learning stage. It can also be observed that in the second stage, the synaptic weight after the second stimulation event decreased significantly less than after the first stimulation event. In addition, the third learning only requires 16 pulses, and due to the slower decay of the third time, it eventually remains at a higher 208.3 µA. This interesting phenomenon is similar to the relearning process in the human brain.

[0042] Fig.11 (a) is the circuit diagram of the MoS2 / PbS heterojunction optoelectronic device used in the "AND" and "OR" gates in this embodiment, and (b) is the circuit diagram of the MoS2 / PbS heterojunction optoelectronic device used in the "AND" and "OR" gates at different optical powers (31.5 mW·cm -2 , 42.7 mW·cm -2), (c) is the logic truth table of the AND and OR gates, and (d) is the relationship diagram between the AND and OR gates with respect to the spike pulse current. The present invention further explores the potential ability of the MoS2 / PbS heterojunction optoelectronic device in this embodiment to perform logical operations by applying light pulses of different wavelengths, and realizes the AND and OR logic functions using 980 nm and 650 nm light pulses, with these two light pulses of the same intensity and duration as two inputs, such as Fig.11 (a) As shown. The turning on and off of the light symbolizes the logical state of the input signal, "1" means the light is on, and "0" means the light is off. Fig.11 As shown in (b), the -2 and 42.7 mW·cm -2 ) under 980 nm and 650 nm light, a threshold current of 207 µA was established to distinguish between "0" and "1". When the photoresponse current value generated by the device is higher than 207 µA, a "1" is output. Conversely, when the current is lower than 207 µA, the output is "0". The corresponding truth table is as follows Fig.11 As shown in (c), it contains two light inputs and two output values. Fig.11 (d) shows the input (light pulse signal) and output (photoresponse current) characteristics of the AND and OR logic functions, where the yellow dashed line represents the critical threshold separating different output states. In the AND logic operation, when the light input intensity is 31.5 mW·cm -2 When the duration is 150 ms, the current exceeds the critical value only when two inputs (650 nm light pulse as input 1 and 980 nm light pulse as input 2) are applied simultaneously. In contrast, when a stronger 42.7 mW·cm -2 When the device is illuminated by light pulses separately or simultaneously, it will generate a current above the threshold (207 µA), thus realizing the light-controlled logic function of the OR gate. More importantly, this innovative method of manipulating optical OR and AND gates is expected to be expanded in the future to facilitate advanced information processing tasks by manufacturing a large number of integrated devices.

[0043] Fig.12 The MoS2 / PbS heterojunction photoelectric device in this embodiment has a power consumption of 42.7 mW·cm -2 The voltage-current diagram under 405-1650 nm light irradiation. The device generates significant photocurrent under light irradiation and exhibits obvious rectifying behavior, indicating that a well-contacted heterojunction has been formed.

[0044] Fig.13The MoS2 / PbS heterojunction photoelectric device in this embodiment has a power consumption of 42.7 mW·cm -2 The photoresponse current diagram under 405-1650 nm light irradiation. The results confirm the superior detection capability of the device in this embodiment in an ultra-wide operating wavelength range. The strongest light response is at 980 nm, and the maximum responsivity (0.013 A·W) is achieved at 980 nm. -1 ), specific detection rate (7.6×10 10 Jones) and extended to the SWIR region (1650 nm), broadening the application of devices in the field of infrared detection.

[0045] Fig.14 The MoS2 / PbS heterojunction photoelectric device in this embodiment has a power consumption of 42.7 mW·cm -2 The device can operate stably over a wide frequency range with a 3 dB bandwidth of 1 kHz. The measured rise time (τ r ) and fall time (τ f ) are 360 ​​µs and 351 µs respectively, which have fast response capability and are suitable for fast communication applications.

[0046] Example 2 The photoelectric performance of the MoS2 / PbS heterojunction photoelectric device can be further regulated by adjusting the thickness of the PbS film. Specifically, the water bath reaction time in the preparation of the PbS film in step 3 of Example 1 is reduced to 10 min to reduce the thickness of the PbS film. The device obtained has a power of 42.7 mW·cm -2 The photoresponse current diagram under 405-1650 nm light irradiation is shown in Fig.15 As shown, it can be seen that compared with Example 1, the photocurrent of the device under the irradiation of light of each wavelength is significantly improved.

[0047] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A bias-controlled MoS2 / PbS heterojunction optoelectronic device, characterized in that: It is a vertical structure two-terminal device, which uses FTO glass as a conductive substrate, and a MoS2 film with a nano-flower ball morphology is grown on the surface of the FTO glass by a hydrothermal method, and a PbS film is grown on the MoS2 film by a water bath method, and the PbS film forms a three-dimensional skeleton coating structure for the MoS2; a first Ag electrode is arranged on the PbS film, and a second Ag electrode is arranged in the area of ​​the FTO glass where the MoS2 film and the PbS film are not grown.

2. The bias-controlled MoS2 / PbS heterojunction optoelectronic device according to claim 1, characterized in that: By adjusting the bias voltage applied to the two Ag electrodes and irradiating light in the ultraviolet to short-wave infrared band, the photoelectric properties of the MoS2 / PbS heterojunction photoelectric device are regulated: under a bias voltage of 0V, the MoS2 / PbS heterojunction photoelectric device achieves broadband photoelectric detection; As the bias voltage increases, the photoelectric synaptic performance of the MoS2 / PbS heterojunction photoelectric device gradually increases.

3. The bias-controlled MoS2 / PbS heterojunction optoelectronic device according to claim 2, characterized in that: The wavelength of the light in the ultraviolet to short-wave infrared band ranges from 405 to 1650 nm.

4. A method for preparing a bias-controlled MoS2 / PbS heterojunction optoelectronic device according to claim 1, 2 or 3, characterized in that: The following steps are involved: Step 1: ultrasonically clean the FTO glass with acetone, ethanol and deionized water in sequence to remove impurities on the surface, and then blow dry with nitrogen; Step 2: Add 0.09 g sodium molybdate and 0.18 g thiourea to 60 mL deionized water and stir evenly, then transfer to a reactor, add the cleaned FTO glass to the reactor, and react at 200 °C for 20-24 h; after the reaction, take out the sample, wash it alternately with deionized water and anhydrous ethanol, and then dry it in an oven at 40-60 °C for 1-2 h to obtain a MoS2 film with a nanoflower morphology; Step 3, add 9.475 g of lead acetate to 100 mL of deionized water and stir until completely dissolved to obtain a lead acetate solution; dissolve 14.7 g of trisodium citrate, 5.71 g of thiourea and 7.84 g of potassium hydroxide in 50 mL of deionized water respectively to obtain a trisodium citrate solution, a thiourea solution and a potassium hydroxide solution; vertically suspend the FTO glass with the MoS2 film grown in the lead acetate solution, then add the trisodium citrate solution, the thiourea solution and the potassium hydroxide solution in turn and stir evenly, then place in a 40°C water bath to react for 10 to 20 min; after the reaction is completed, take out the sample and wash it alternately with deionized water and anhydrous ethanol, then place it in an oven at 40 to 60°C and dry it for 1 to 2 h to obtain a PbS film; Step 4: Scrape off the MoS2 film and PbS film on part of the surface of the FTO glass to expose the FTO conductive layer; then deposit a first Ag electrode on the PbS film, and deposit a second Ag electrode on the area of ​​the FTO glass where the MoS2 film and PbS film are not grown, thereby completing the preparation of the MoS2 / PbS heterojunction photoelectric device.

5. Application of the bias-regulated MoS2 / PbS heterojunction optoelectronic device according to claim 1, 2 or 3 in light-responsive artificial synapses or photoelectric detection in the ultraviolet to short-wave infrared range.

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