A bifunctional quantum dot and a preparation method, product and application thereof

Abstract

The application discloses a kind of bifunctional quantum dots and preparation method, product and application thereof, belong to semiconductor nanophotovoltaic material technical field.The bifunctional quantum dots provided in the application include: core-shell structure quantum dots, and perovskite is compounded outside the core-shell structure quantum dots;The core-shell structure quantum dots include: mercury selenide quantum dot core, and lead selenide shell is covered outside the mercury selenide quantum dot core.The bifunctional material provided in the application exhibits microsecond level response time under short-wave infrared light signal excitation, and high-fidelity two-dimensional photoelectric imaging is constructed by single-point scanning system;Under the irradiation of mid-wave infrared light pulse, it shows slow relaxation characteristics, can simulate the double-pulse facilitation and learning-forgetting dynamic mechanism of biological synapse, and has wide application value in the field of artificial intelligence calculation.

Description

Technical Field

[0001] This application belongs to the field of semiconductor nano-optoelectronic materials technology, and particularly relates to a bifunctional quantum dot, its preparation method, products and applications. Background Technology

[0002] Infrared detection technology plays an irreplaceable role in intelligent detection fields such as machine vision, autonomous driving, and neuromorphic computing. Colloidal quantum dots (CQDs) have become core candidate materials due to their advantages such as tunable bandgap and broad-spectrum absorption. Traditional quantum dot synthesis and surface passivation processes often have highly singular objectives. They either pursue extremely low defect densities through extreme surface passivation to meet the needs of rapid imaging, or deliberately introduce deep-level trapped states for information storage.

[0003] Limited by the inherent properties of existing material systems, quantum dot materials with a single formulation cannot simultaneously achieve both "fast" and "slow" carrier dynamics, forcing current intelligent vision systems to adopt multi-module heterogeneous integration schemes. This not only significantly increases the system's size and power consumption but also becomes a core technological bottleneck restricting breakthroughs in integrated sensing and computing chip technology.

[0004] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of protection of this application. Summary of the Invention

[0005] This application discloses a bifunctional quantum dot, its preparation method, products, and applications, aiming to solve the technical problem of system redundancy caused by the single function of existing quantum dots.

[0006] To achieve the above objectives, the technical solution of this application is: The first aspect of this application provides a bifunctional quantum dot, comprising: a core-shell quantum dot, and a perovskite composite outside the core-shell quantum dot; The core-shell structured quantum dot comprises: a mercury selenide quantum dot core, and a lead selenide shell layer covering the mercury selenide quantum dot core.

[0007] Preferably, in conjunction with the first aspect, a mercury selenide / lead selenide interface is formed within the core-shell quantum dot structure; The core-shell structured quantum dots and the perovskite form a quantum dot / perovskite microheterojunction interface. The general formula of the perovskite is A2BX4; Where: A is butylamine ion; B is either lead ion or tin ion; X represents iodide ions, bromide ions, or chloride ions.

[0008] The second aspect of this application provides a method for preparing the bifunctional quantum dots described in the first aspect, the method comprising: At a first temperature, a selenium source is added to a first organic amine solvent to react and obtain a selenium precursor; At a second temperature, a mercury source is added to a second organic amine solvent to react and obtain a mercury precursor; At a third temperature, the selenium precursor and the mercury precursor are reacted, and then quenched and purified at a fourth temperature to obtain mercury selenide quantum dots. Provide perovskite precursors; The perovskite precursor and the mercuric selenide quantum dots are reacted to form a lead selenide shell layer in situ on the surface of the mercuric selenide quantum dot core through cation exchange, thus obtaining the bifunctional quantum dots.

[0009] Preferably, in conjunction with the second aspect, the first temperature is 160 ℃-200 ℃, and the reaction time at the first temperature is 2-4 h; The second temperature is 110 ℃-120 ℃, and the reaction time at the second temperature is 45-75 min; The third temperature is 105 ℃-125 ℃, and the reaction time at the third temperature is 20-30 min; The fourth temperature is 0 ℃-5 ℃, and the quenching time at the fourth temperature is 3-8 min.

[0010] Preferably, in conjunction with the first aspect, the first organic amine solvent is one or more of oleylamine, dodecylamine, hexadecylamine, or octadecylamine; and / or The second organic amine solvent is one or more of oleylamine, dodecylamine, hexadecylamine, or octadecylamine; and / or The selenium source is one or a combination of selenourea or selenium powder; and / or The mercury source is one or more of mercuric iodide, mercuric chloride, mercuric bromide, or mercuric acetate.

[0011] Preferably, in conjunction with the first aspect, the first organic amine solvent and / or the second organic amine solvent, before the reaction, comprise: The first organic amine solvent and / or the second organic amine solvent are subjected to dehydration and deoxygenation treatment at 100 ℃-120 ℃ for 30-60 min.

[0012] A third aspect of this application provides an optoelectronic device, comprising: a functional layer; The functional layer includes bifunctional quantum dots as described in the first aspect or bifunctional quantum dots prepared using the preparation method described in the second aspect.

[0013] The fourth aspect of this application provides a method for fabricating the optoelectronic device described in the third aspect, the method comprising: A substrate is provided, and an insulating layer is formed on the surface of the substrate; A metal layer is formed on the surface of the insulating layer; A bifunctional quantum dot layer is formed on the metal layer.

[0014] Preferably, in conjunction with the fourth aspect, the substrate is one of a single-crystal silicon wafer, a glass substrate, a quartz substrate, a sapphire substrate, or a flexible polymer substrate; and / or The insulating layer is one of SiO2 insulating layer, Al2O3 insulating layer, HfO2 insulating layer or Si3N4 insulating layer; and / or The metal layer is one or more of chromium, titanium, gold, platinum, silver, or indium tin oxide.

[0015] The fifth aspect of this application provides the application of the optoelectronic device described in the third aspect or the optoelectronic device prepared by the preparation method described in the fourth aspect in an intelligent detection device.

[0016] Compared with the prior art, the advantages or beneficial effects of the embodiments of this application include at least the following: The bifunctional quantum dot provided in this application is based on a micro heterojunction formed by core-shell quantum dots and perovskite, with each component tightly bonded and the interface properties controllable. Under short-wave infrared light excitation, it can utilize the interface of the quantum dot and perovskite micro heterojunction to realize an efficient charge transport channel, exhibiting a microsecond-level response time. This can be used to construct a high-fidelity two-dimensional photoelectric imaging system, achieving accurate reconstruction of the target spatial pattern and ensuring imaging clarity and timely response. Under mid-wave infrared light pulse irradiation, charge carriers are trapped and captured by the interface formed by mercury selenide and lead selenide, and the device exhibits slow relaxation characteristics, which can simulate the two-pulse facilitation and learning-forgetting dynamic mechanism of biological synapses. By mapping its conductivity modulation weights to an artificial neural network, it can achieve highly robust MNIST handwritten digit recognition in noisy environments, fully demonstrating its application value in the field of artificial intelligence computing. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the preparation process provided in the embodiments of this application; Figure 2 TEM image of A1-bifunctional quantum dot provided in the embodiments of this application; Figure 3XRD patterns of A1-bifunctional quantum dots and A2-bifunctional quantum dots provided in embodiments of this application; Figure 4 XRD patterns of A1-bifunctional quantum dots and B1-quantum dots provided in embodiments of this application; Figure 5 This is a schematic diagram of the structure of an optoelectronic device made of Al-bifunctional quantum dots provided in an embodiment of this application; Figure 6 Photocurrent response spectrum of the optoelectronic device provided in the embodiments of this application in the visible to short-wave infrared range; Figure 7 A microsecond-level fast transient response curve of the optoelectronic device provided in the embodiments of this application at a wavelength of 1550 nm; Figure 8 The optoelectronic device provided in this application provides an image reconstruction application for infrared single-point scanning high-resolution imaging at a wavelength of 1550 nm; Figure 9 The slow relaxation synaptic response curve of the optoelectronic device provided in the embodiments of this application under mid-wave infrared excitation (4000 nm); Figure 10 PPF index diagram of the optoelectronic device provided in the embodiments of this application; Figure 11 The simulation test curve of the "learning-forgetting-relearning" optical memory behavior of the optoelectronic device based on the Ebbinghaus model provided in the embodiments of this application is shown. Figure 12 The topology diagram of the artificial neural network that maps the synaptic weights of the optoelectronic device provided in the embodiments of this application is shown. Figure 13 This is a noise resistance identification test diagram of an optoelectronic device provided in an embodiment of this application. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0020] In the following description of this embodiment, the term "and / or" is used to describe the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, B existing alone, and A and B existing simultaneously. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0021] In the following description of this embodiment, the term "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0022] Those skilled in the art should understand that, in the following description of the embodiments of this application, the sequence of numbers does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0023] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms "a" and "the" as used in the embodiments of this application and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise.

[0024] It should be noted that all raw materials and / or reagents in the embodiments of this application were purchased on the market or prepared according to conventional methods known to those skilled in the art.

[0025] In a first aspect, this application provides a bifunctional quantum dot, comprising: a core-shell quantum dot, and a perovskite composite outside the core-shell quantum dot; the core-shell quantum dot comprises: a mercury selenide quantum dot core, and a lead selenide shell layer covering the mercury selenide quantum dot core.

[0026] It should be noted that the bifunctional quantum dot fabricated in this application has both infrared imaging capabilities in the first band of 500-2000 nm and slow relaxation characteristics in the second band of 3000-5000 nm.

[0027] In this embodiment, a mercury selenide / lead selenide interface (HgSe / PbSe interface) is formed within the core-shell quantum dot; the core-shell quantum dot and the perovskite form a quantum dot / perovskite micro-heterojunction interface; the perovskite has the general formula A2BX4; wherein: A is butylamine ion; B is lead ion or tin ion; X is iodide ion, bromide ion or chloride ion, preferably butylamine lead iodide ((C4H9NH3)2PbI4). This application achieves the synergy of band structure and defect state by constructing a unique dual-interface structure of mercury selenide quantum dot / lead selenide interface and quantum dot / perovskite micro-heterojunction interface in situ. The internal HgSe / PbSe interface has a large defect density, serving as a trap center for low-energy charge carriers in the mid-wave infrared; while the surface quantum dot / perovskite micro-heterojunction interface has an extremely small defect density, providing excellent surface passivation and efficient charge transport channels.

[0028] It should be noted that, based on the above-mentioned dual-interface modulation mechanism, under short-wavelength (vis-NIR) excitation, the high-energy photogenerated carriers of this bifunctional quantum dot material are dominated and rapidly extracted by the low-defect-density quantum dot / perovskite micro heterojunction interface, achieving a high-speed response at the microsecond level, which is suitable for transient imaging functions in intelligent detection; under medium-wavelength (MIR) excitation, the low-energy carriers are strongly controlled by the high-defect-density mercury selenide quantum dot / lead selenide interface trap states, resulting in a significant trapping and slow release process, exhibiting slow relaxation characteristics, thus demonstrating photoelectric synaptic function.

[0029] As a preferred embodiment, the micro heterojunction formed by the core-shell quantum dots and the perovskite composite described in this application preferably has an overall average particle size range of 5 nm-30 nm, more preferably 8 nm-15 nm. By controlling the overall size of the micro heterojunction within the above-mentioned nanoscale range, it is possible to ensure a microscopic synergistic effect between the high-defect-density HgSe / PbSe internal interface and the low-defect-density quantum dot / perovskite external composite interface. This ensures rapid charge extraction in the short-wave infrared while maintaining significant carrier trapping and slow relaxation characteristics in the mid-wave infrared.

[0030] Secondly, this application provides a method for preparing the bifunctional quantum dots described in the first aspect, the method comprising: At a first temperature, a selenium source is added to a first organic amine solvent to react and obtain a selenium precursor; At a second temperature, a mercury source is added to a second organic amine solvent to react and obtain a mercury precursor; At a third temperature, the selenium precursor and the mercury precursor are reacted, and then quenched and purified at a fourth temperature to obtain mercury selenide quantum dots. Provide perovskite precursors; The perovskite precursor and the mercuric selenide quantum dots are reacted to form a lead selenide shell layer in situ on the surface of the mercuric selenide quantum dot core through cation exchange, thus obtaining the bifunctional quantum dots.

[0031] Specifically, in the preparation method described in this application, providing the perovskite precursor includes: dissolving lead iodide, lead bromide, and dimethylamine hydroiodide (DMAI) in N,N-dimethylformamide (DMF) solvent to obtain the perovskite precursor. Specifically, in the preparation method described in this application, the core-shell structured quantum dots, after ligand exchange and centrifugation purification, are redispersed in a polar mixed solvent containing butylamine and DMF. In this process, butylamine acts as an organic cation source, forming butylamine lead iodide perovskite through in-situ recombination.

[0032] In this embodiment, the first temperature is preferably 160℃-200℃, and the reaction time at the first temperature is preferably 2-4 h. By controlling the first temperature and time, the selenium source can be fully dissolved and coordinated in the first organic amine solvent, forming a uniformly active and stable selenium coordination precursor with the organic amine. The second temperature is preferably 110℃-120℃, and the reaction time at the second temperature is preferably 45-75 min. By controlling the second temperature and time, the mercury source can be completely dissolved in the second organic amine and coordinated with the amine solvent to prepare an activity-matched, monodisperse mercury precursor. The third temperature is preferably 105℃-125℃, and the reaction time at the third temperature is preferably 20-30 min. By controlling the third temperature and time, the initial nucleation density and final particle size range of the quantum dots can be adjusted, while the coating degree of the surface organic amine ligands can be adjusted to reduce crystal defects and ensure optical and relaxation properties. The fourth temperature is preferably 0℃-5℃, and the quenching time at the fourth temperature is preferably 3-8 min. By controlling the rapid cooling of the fourth temperature, the crystal growth and Oswald ripening can be stopped immediately by rapid cooling quenching, ensuring the size and structural integrity of the quantum dots.

[0033] In this embodiment, the first organic amine solvent is preferably one or more of oleylamine, dodecylamine, hexadecylamine, or octadecylamine; the second organic amine solvent is preferably one or more of oleylamine, dodecylamine, hexadecylamine, or octadecylamine; the selenium source is preferably one or a combination of selenourea or selenium powder; and the mercury source is preferably one or more of mercuric iodide, mercuric chloride, mercuric bromide, or mercuric acetate. The organic amine solvent used in this application serves simultaneously as a reaction solvent and a surface ligand. Its amino groups can coordinate with metal ions, while the long carbon chains provide steric hindrance to prevent uncontrolled aggregation of quantum dots. By selecting organic amines with different carbon chain lengths, the reactivity of the precursor and the nucleation and growth kinetics of the quantum dots can be effectively controlled, thereby precisely controlling the size and morphology of the quantum dots.

[0034] Specifically, the selenium source used in this application is the selenium element required for quantum dot synthesis, preferably one or a combination of selenourea or selenium powder. Selecting selenium sources with different reactivity—selenourea being highly reactive and selenium powder having relatively stable reactivity—can be used to adjust the release rate of the selenium precursor at a specific temperature to adapt to the reaction kinetics of microheterojunction growth.

[0035] Specifically, the mercury source used in this application can provide the mercury ions required for quantum dot synthesis, preferably one or more of mercuric iodide, mercuric chloride, mercuric bromide, or mercuric acetate. The anions carried by different mercury sources, such as iodide ions, chloride ions, bromide ions, or acetate ions, not only affect the solubility of the precursor, but also participate in surface passivation in situ during quantum dot growth, thereby regulating the defect state density on the quantum dot surface and providing an interfacial basis for the subsequent bonding of perovskite to form high-quality micro heterojunctions.

[0036] In this embodiment, before the reaction, the first organic amine solvent and / or the second organic amine solvent undergo a dehydration and deoxygenation treatment at 100 ℃-120 ℃ for 30-60 min. This pretreatment removes water and oxygen from the organic amine solvent, avoids hydrolysis and oxidation by adding mercury / selenium sources, ensures high activity and coordination stability of the precursor, reduces quantum dot lattice defects and impurity phase formation, and guarantees the uniformity of quantum dot morphology and size, as well as the stability of dual-band functional performance.

[0037] Specifically, the perovskite precursor and the mercury selenide quantum dots are reacted to form a lead selenide shell in situ on the surface of the mercury selenide quantum dot core through cation exchange. During this process, not only does phase transfer occur, but more importantly, the Pb source undergoes an in-situ cation exchange / epitaxy reaction on the HgSe surface to form an extremely thin PbSe shell. At the same time, the perovskite halide ligands are tightly composited on the PbSe surface to form micro heterojunctions, thereby constructing an HgSe / PbSe interface and a quantum dot / perovskite dual-interface structure with different defect densities.

[0038] Thirdly, this application provides an optoelectronic device, comprising: a functional layer; the functional layer comprising the bifunctional quantum dots described in the first aspect or bifunctional quantum dots prepared by the method described in the second aspect. Based on the excellent comprehensive performance of the aforementioned bifunctional quantum dots, an efficient transmission channel based on a micro-heterojunction interface can be provided for the optoelectronic device: after applying a bias voltage and inputting a visible to short-wave infrared light signal, the device exhibits microsecond-level response characteristics by utilizing the efficient transmission characteristics of the quantum dot / perovskite micro-heterojunction interface, which can be used to construct a high-fidelity two-dimensional optoelectronic imaging system. Utilizing the high defect density inside the quantum dot, when a mid-wave infrared light pulse is input, the charge carriers are trapped by the HgSe / PbSe interface, causing the device to exhibit slow relaxation characteristics, thereby simulating the two-pulse facilitation (PPF) and "learning-forgetting" mechanism of biological synapses. Mapping the conductivity modulation weights of the device to an artificial neural network enables highly robust MNIST handwritten digit recognition in noisy environments.

[0039] Fourthly, this application provides a method for fabricating the optoelectronic device described in the third aspect, the method comprising: A substrate is provided, and an insulating layer is formed on the surface of the substrate; A metal layer is formed on the surface of the insulating layer; A bifunctional quantum dot layer is formed on the metal layer.

[0040] In this embodiment, the substrate is preferably one of a single-crystal silicon wafer, a glass substrate, a quartz substrate, a sapphire substrate, or a flexible polymer substrate, which aims to provide a flat standard semiconductor support platform to facilitate the fabrication and subsequent integration of micro- and nano-devices. The insulating layer is preferably one of a SiO2 insulating layer, an Al2O3 insulating layer, a HfO2 insulating layer, or a Si3N4 insulating layer, which aims to provide good electrical isolation and effectively suppress leakage current in the substrate direction, thereby reducing dark current noise and static power consumption of photodetectors and synaptic devices. The metal layer is preferably one or more of chromium, titanium, gold, platinum, silver, or indium tin oxide, more preferably a chromium / gold interdigitated electrode, wherein the Cr layer acts as an adhesion layer to significantly enhance the bonding force between the electrode and the insulating layer, and the Au layer provides excellent conductivity and chemical stability to achieve efficient charge transfer with bifunctional quantum dots. In addition, the interdigitated structure design can effectively increase the effective photosensitive area of ​​the device and shorten the channel transport distance of charge carriers, thereby greatly improving the photoresponsivity, charge collection efficiency, and modulation efficiency of synaptic weights of the device.

[0041] It should be noted that this application uses a single-crystal silicon wafer with a 285 nm SiO2 insulating layer and Cr / Au interdigitated electrodes as a substrate. A spin-coating process is used to prepare a uniform functional layer from the bifunctional quantum dot solution of this application, resulting in a photoelectric synapse device with two ends. Under short-wave infrared light signals, this device can achieve microsecond-level fast response by utilizing the efficient charge transport channels at the quantum dot / perovskite micro-heterojunction interface, making it suitable for high-fidelity photoelectric imaging. Under mid-wave infrared light pulses, it can achieve slow relaxation characteristics through the carrier trapping effect of the internal mercury selenide / lead selenide interface, simulating the double-pulse facilitation and learning-forgetting behavior of biological synapses. After mapping the conductivity modulation weights of this device to an artificial neural network, it can achieve highly robust MNIST handwritten digit recognition in noisy environments, demonstrating the application value of this bifunctional quantum dot in the field of artificial intelligence computing.

[0042] Fifthly, this application provides the application of the optoelectronic device described in the third aspect or the optoelectronic device prepared by the method described in the fourth aspect in intelligent detection devices. Based on the optoelectronic device prepared above, it exhibits a microsecond-level (70-80 μs) response time under visible to short-wave infrared light signal excitation, enabling the construction of a high-fidelity two-dimensional optoelectronic imaging system. Under mid-wave infrared light pulses, the optoelectronic device exhibits slow relaxation characteristics, simulating the double-pulse facilitation (PPF) and "learning-forgetting" mechanism of biological synapses. By mapping its conductivity modulation weights to an artificial neural network, highly robust MNIST handwritten digit recognition can be achieved in noisy environments. It can be integrated into intelligent detection devices such as UAV inspection, airborne remote sensing, intelligent reconnaissance, and deep space optoelectronic detection, realizing the integration of multispectral sensing, brain-like information processing, and real-time intelligent recognition, significantly simplifying the detection system structure, reducing power consumption, and improving environmental adaptability.

[0043] The technical solution of this application will be further described below with reference to specific embodiments.

[0044] Example 1 This embodiment provides a method for preparing A1-bifunctional quantum dots, the preparation process of which is as follows: Figure 1 As shown, it specifically includes: S101: 30 ml of oleylamine was dehydrated and deoxygenated at 115 °C for 60 minutes; then 0.378 g of selenourea was added, and the mixture was heated to 180 °C and reacted for 3 hours to obtain the selenium precursor.

[0045] S102: 20 ml of oleylamine was dehydrated and deoxygenated at 115 °C for 60 minutes; then 0.252 g of scarlet mercuric iodide (HgI2) was added and dissolved at 115 °C to obtain the mercury precursor.

[0046] S103: At 115 °C, 5 ml of selenium precursor was rapidly thermally injected into 20 ml of mercury precursor and reacted for 25 minutes. The reaction was then quenched in an ice bath and purified using methanol and toluene in multiple stages. Finally, the mixture was dispersed in 20 ml of n-hexane to obtain the initial HgSe quantum dot stock solution.

[0047] S104: Dissolve 0.553 g lead iodide (PbI2), 0.172 g dimethylamine hydroiodate (DMAI) and 0.073 g lead bromide (PbBr2) in 10 ml DMF solution to form a clear solution and obtain the perovskite precursor.

[0048] S105: The above perovskite precursor solution is vigorously mixed with HgSe quantum dot stock solution. During this process, not only does phase transfer occur, but more importantly, the Pb source undergoes an in-situ cation exchange / epitaxy reaction on the HgSe surface, forming an extremely thin PbSe shell. After washing with n-hexane and inducing precipitation with toluene, the product is redispersed in a polar mixed solvent of DMF and n-butylamine. In this process, n-butylamine, as an organic cation source, recombines in situ with the lead halide component on the surface of the core-shell quantum dots to form butylamine lead-iodide perovskite, thereby constructing a dual-interface structure of HgSe / PbSe and quantum dot / perovskite microheterojunctions with different defect densities, obtaining the final Al-bifunctional quantum dots.

[0049] Example 2 This embodiment provides a method for preparing A2-bifunctional quantum dots, aiming to regulate the surface cation exchange kinetics and defect state density at the micro-heterojunction interface by adjusting the amount of dimethylamine hydroiodate (DMAI) in the perovskite precursor. Specifically, the method includes: S201: 30 ml of oleylamine was dehydrated and deoxygenated at 115 °C for 60 minutes; then 0.378 g of selenourea was added, and the mixture was heated to 180 °C and reacted for 3 hours to obtain the selenium precursor.

[0050] S202: 20 ml of oleylamine was dehydrated and deoxygenated at 115 °C for 60 minutes; then 0.252 g of scarlet mercuric iodide (HgI2) was added and dissolved at 115 °C to obtain the mercury precursor.

[0051] S203: At 115 °C, 5 ml of selenium precursor was rapidly thermally injected into 20 ml of mercury precursor and reacted for 25 minutes. The reaction was then quenched in an ice bath and purified using methanol and toluene in multiple stages. Finally, the mixture was dispersed in 20 ml of n-hexane to obtain the initial HgSe quantum dot stock solution.

[0052] S204: Dissolve 0.553 g lead iodide (PbI2), 0.344 g dimethylamine hydroiodate (DMAI) and 0.073 g lead bromide (PbBr2) in 10 ml DMF solution to form a clear solution and obtain the perovskite precursor.

[0053] S205: The lead halide precursor solution was vigorously mixed with the HgSe quantum dot stock solution. During this process, not only did phase transfer occur, but more importantly, the Pb source underwent an in-situ cation exchange / epitaxial reaction on the HgSe surface, forming an extremely thin PbSe shell. After washing with hexane and inducing precipitation with toluene, the product was redispersed in a polar mixed solvent of DMF and n-butylamine. In this process, n-butylamine, as an organic cation source, in-situ recombines with the lead halide component on the surface of the core-shell quantum dots to form butylamine lead-iodide perovskite, thereby constructing a dual-interface structure of HgSe / PbSe and quantum dot / perovskite microheterojunctions with different defect densities, obtaining the final A2-bifunctional quantum dots.

[0054] Meanwhile, to verify the overall performance of the bifunctional quantum dots prepared in the above embodiments, this application provides the following comparative examples for illustration.

[0055] Comparative Example 1 This comparative example provides a preparation method for bifunctional quantum dots. The component ratios, preparation operations, and process parameters are basically the same as those in Example 1. The only difference is that dimethylamine hydroiodide (DMAI) was not added in S104 of this comparative example to obtain B1-quantum dots.

[0056] To investigate the morphology of the bifunctional quantum dot material used in this application, TEM analysis was performed on the bifunctional quantum dot material prepared in Example 1. The characterization results are as follows: Figure 2 As shown.

[0057] Depend on Figure 2 It is known that the bifunctional quantum dots prepared in this application all exhibit a regular morphology of approximately spherical shape with clear outlines and no rod-shaped, sheet-like or irregular agglomerates. This indicates that the synthesis process has a high degree of control over the particle morphology, and the particle boundaries are distinct, with no obvious particle fusion or amorphous adhesion.

[0058] according to Figure 3 It can be seen that XRD tests were performed on the A1-bifunctional quantum dots and A2-bifunctional quantum dots prepared in Examples 1 and 2, with the horizontal axis 2Theta (degree) representing the diffraction angle 2. The vertical axis represents diffraction intensity. A comparison reveals that adding an excessive amount of dimethylamine hydroiodide (DMAI) does not alter its crystal structure.

[0059] according to Figure 4It can be seen that XRD tests on the A1-bifunctional quantum dots and B1-quantum dots prepared in Example 1 and Comparative Example 1 show that the comparative example without DMAI could not form the butylamine lead iodide perovskite phase in the subsequent reaction, which proves the key role of DMAI in inducing the in-situ composite crystallization of this specific perovskite phase.

[0060] To verify the application of the bifunctional quantum dots provided in this application in optoelectronic devices, the optoelectronic device structure constructed from the bifunctional quantum dots prepared in Example 1 is as follows. Figure 5 As shown.

[0061] Using a single-crystal silicon wafer with a 285 nm SiO2 insulating layer and Cr / Au interdigitated electrodes as a substrate, the bifunctional quantum dot solution of this application is prepared into a uniform functional layer with a thickness of about 122 nm by spin coating process, and then annealed at 100-150 °C to obtain an optoelectronic device with two ends.

[0062] Depend on Figure 5 As can be seen, the three incident beams of light from above directly demonstrate that the optoelectronic device has a wide-band spectral response and detection capability covering visible light, near-infrared light to mid-infrared light.

[0063] The photocurrent response spectrum and microsecond-level fast transient response curve of the above-prepared optoelectronic device in the visible to short-wave infrared range are shown below. Figure 6 and Figure 7 As shown.

[0064] according to Figure 6 The figure shows the spectral response curve of the optoelectronic device. The X-axis represents the wavelength of the incident light, and the Y-axis represents the magnitude of the photocurrent generated by the device under illumination of light of the corresponding wavelength. The curve rises from 500 nm and falls back to 0 after about 1700 nm, indicating that the effective photoresponse range of the device covers a wide spectral region of 500-1700 nm.

[0065] according to Figure 7 The figure shows the microsecond-level fast transient response curves at a wavelength of 1550 nm. The rise time (10%-90%) of the optoelectronic device is 74 μs, and the fall time (90%-10%) is 81 μs, both within the microsecond range. This result demonstrates that in the short-wave infrared band, bifunctional quantum dot devices exhibit high charge transport efficiency and extremely fast information capture and recovery speed when performing photoelectric detection functions, with no obvious trap-induced relaxation. This provides performance support for constructing a high frame rate, low ghosting two-dimensional optoelectronic imaging system.

[0066] The image will be reconstructed using a short-wave infrared single-point scanning high-resolution imaging application based on this optoelectronic device, such as... Figure 8As shown, it still has near-infrared high-resolution imaging capabilities at a wavelength of 1550 nm, and demonstrates that the brightness and contrast of its imaging can be significantly enhanced by adjusting the bias voltage (+1 V to +5 V), successfully achieving high-quality reconstruction of target spatial patterns such as the "orange" pattern.

[0067] This application presents the slow relaxation synaptic response curve and PPF index diagram of the aforementioned optoelectronic device under mid-wave infrared excitation, as follows: Figure 9 and Figure 10 As shown.

[0068] according to Figure 9 As shown, the slow relaxation synaptic response curve under 4000 nm excitation exhibits an increasing current trend at different voltages after the signal is turned on. After the signal is removed, the photocurrent of the device shows a significant slow relaxation decay behavior, which stems from the carrier trapping effect at the mercury selenide / lead selenide interface in the bifunctional quantum dot. This characteristic can accurately simulate the learning-forgetting dynamics and double-pulse facilitation behavior of biological synapses, providing a key foundation for constructing optoelectronic synaptic devices based on artificial neural networks and fully demonstrating its application value in the field of artificial intelligence computing.

[0069] according to Figure 10 As shown in the inset, the small plot represents the current-time curve. Under two consecutive pulse stimuli, the device generates two current responses, labeled ΔA1 (response amplitude of the first pulse) and ΔA2 (response amplitude of the second pulse), respectively. The ratio PPF(%) = ΔA2 / ΔA1 × 100% is the Y-axis of the main plot. When the pulse interval is extremely short, the PPF value can reach over 160%, exhibiting a significant facilitation effect. As the interval time increases, the PPF rapidly decays and eventually approaches 100%, a process highly consistent with the slow relaxation characteristics induced by carrier traps. This result demonstrates that the optoelectronic device successfully simulates the short-term plasticity of biological synapses, providing core support for constructing brain-like artificial neural networks.

[0070] The simulation test curves of the "learning-forgetting-relearning" optical memory behavior of the device based on the Ebbinghaus model provided in the embodiments of this application are as follows: Figure 11 As shown, during the initial learning phase, the device achieves stable modulation of its conductance state after 15 cycles of light pulse stimulation, i.e., "memory" formation. Following a 10-second period of unstimulated forgetting, the device's conductance partially decays. When the same light pulse stimulation is applied again, the device recovers to its initial stable conductance state in just 7 cycles, demonstrating a significant improvement in "relearning" efficiency. This behavior perfectly simulates the memory reinforcement and reconsolidation process of biological synapses.

[0071] The artificial neural network topology mapping the synaptic weights of the optoelectronic device and the noise-resistant recognition test diagram provided in the embodiments of this application are as follows: Figure 12 and Figure 13 As shown.

[0072] according to Figure 12 The diagram shows a neural network model built based on the characteristics of optoelectronic devices, illustrating its hardware-level computational architecture for MNIST handwritten digit image recognition. This architecture includes an input layer, hidden layers, and an output layer that map pixels to synaptic weights. The input layer consists of handwritten digit images from the MNIST dataset, each image being a 28×28 pixel grayscale image with a total of 784 neurons, each neuron corresponding to the grayscale value of one pixel. The hidden layer contains 100 neurons ranging from 0 to 99, each fully connected to all 784 neurons in the input layer, with a weight of W. IH Each hidden layer neuron performs a weighted sum of the input pixel values, then outputs an abstract feature through an activation function. The output layer contains 10 neurons, corresponding to the 10 categories of digits 0-9. Each neuron is fully connected to the 100 neurons in the hidden layer, with a weight of W. HO Finally, by using an activation function, the probability of each category is output, which accurately maps to the final classification result.

[0073] according to Figure 13 This demonstrates that the neural network system constructed from this optoelectronic device maintains an extremely high image recognition accuracy of over 55% even when faced with system readout noise interference at different operating frequencies. The network exhibits high recognition accuracy even in noisy environments, demonstrating excellent noise robustness. This also verifies the high reliability and excellent fault tolerance of this bifunctional quantum dot material when performing complex artificial intelligence tasks.

[0074] Finally, the bifunctional quantum dot provided in this application is based on a core-shell structure and perovskite composite to form a micro heterojunction, with each component tightly bonded and the interface properties controllable. Under short-wave infrared light excitation, it can utilize the efficient charge transport channel at the quantum dot / perovskite micro heterojunction interface to exhibit a microsecond-level response time, which can be used to construct a high-fidelity two-dimensional optoelectronic imaging system to ensure the clarity of imaging and the timeliness of response. Under mid-wave infrared light pulse irradiation, charge carriers are trapped by mercuric selenide / lead selenide interface traps, and the device exhibits slow relaxation characteristics, which can simulate the dual-pulse facilitation and learning-forgetting dynamic mechanism of biological synapses.

[0075] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A bifunctional quantum dot, characterized in that, include: Core-shell quantum dots, and perovskite composites outside the core-shell quantum dots; The core-shell structured quantum dot comprises: a mercury selenide quantum dot core, and a lead selenide shell layer covering the mercury selenide quantum dot core.

2. The bifunctional quantum dot according to claim 1, characterized in that, A mercury selenide / lead selenide interface is formed within the core-shell quantum dot. The core-shell structured quantum dots and the perovskite form a quantum dot / perovskite microheterojunction interface. The general formula of the perovskite is A2BX4; Where: A is butylamine ion; B is either lead ion or tin ion; X represents iodide ions, bromide ions, or chloride ions.

3. A method for preparing a bifunctional quantum dot according to any one of claims 1-2, characterized in that, The preparation method includes: At a first temperature, a selenium source is added to a first organic amine solvent to react and obtain a selenium precursor; At a second temperature, a mercury source is added to a second organic amine solvent to react and obtain a mercury precursor; At a third temperature, the selenium precursor and the mercury precursor are reacted, and then quenched and purified at a fourth temperature to obtain mercury selenide quantum dots. Provides perovskite precursors; The perovskite precursor and the mercuric selenide quantum dots are reacted to form a lead selenide shell layer in situ on the surface of the mercuric selenide quantum dot core through cation exchange, thus obtaining the bifunctional quantum dots.

4. The method for preparing bifunctional quantum dots according to claim 3, characterized in that, The first temperature is 160℃-200℃, and the reaction time at the first temperature is 2-4 h; The second temperature is 110 ℃-120 ℃, and the reaction time at the second temperature is 45-75 min; The third temperature is 105 ℃-125 ℃, and the reaction time at the third temperature is 20-30 min; The fourth temperature is 0 ℃-5 ℃, and the quenching time at the fourth temperature is 3-8 min.

5. The method for preparing bifunctional quantum dots according to claim 3, characterized in that, The first organic amine solvent is one or more of oleylamine, dodecylamine, hexadecylamine, or octadecylamine; and / or The second organic amine solvent is one or more of oleylamine, dodecylamine, hexadecylamine, or octadecylamine; and / or The selenium source is one or a combination of selenourea or selenium powder; and / or The mercury source is one or more of mercuric iodide, mercuric chloride, mercuric bromide, or mercuric acetate.

6. The method for preparing bifunctional quantum dots according to claim 5, characterized in that, The first organic amine solvent and / or the second organic amine solvent, before the reaction, comprise: The first organic amine solvent and / or the second organic amine solvent are subjected to dehydration and deoxygenation treatment at 100 ℃-120 ℃ for 30-60 min.

7. An optoelectronic device, characterized in that, include: Functional layer; The functional layer includes bifunctional quantum dots as described in any one of claims 1-2 or bifunctional quantum dots prepared by the preparation method described in any one of claims 3-6.

8. A method for fabricating the optoelectronic device according to claim 7, characterized in that, The preparation method includes: A substrate is provided, and an insulating layer is formed on the surface of the substrate; A metal layer is formed on the surface of the insulating layer; A bifunctional quantum dot layer is formed on the metal layer.

9. The method for fabricating the optoelectronic device according to claim 8, characterized in that, The substrate is one of a single-crystal silicon wafer, a glass substrate, a quartz substrate, a sapphire substrate, or a flexible polymer substrate; and / or The insulating layer is one of SiO2 insulating layer, Al2O3 insulating layer, HfO2 insulating layer or Si3N4 insulating layer; and / or The metal layer is one or more of chromium, titanium, gold, platinum, silver, or indium tin oxide.

10. The application of the optoelectronic device according to claim 7 or the optoelectronic device prepared by any one of claims 8-9 in an intelligent detection device.

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