Methods for improving the performance of wide-bandgap perovskite heterojunction ultraviolet optoelectronic synaptic devices

Abstract

This invention, belonging to the field of optoelectronic devices, discloses a method for improving the performance of a wide-bandgap perovskite heterojunction ultraviolet photoelectric synaptic device. This device achieves ultraviolet photoelectric neural synaptic functionality through a heterojunction formed by a PEDOT:PSS hole transport layer and a wide-bandgap perovskite PEA2PbCl4 film. By doping the PEA2PbCl4 film with B3PyMPM as an electron-trapping site, the electron-trapping capability is enhanced, thereby improving the performance of the ultraviolet photoelectric synaptic device. The method is simple, avoids the need for expensive equipment, and reduces device production costs.

Description

Technical Field

[0001] The present invention belongs to the field of optoelectronic devices, and in particular relates to a method for improving the performance of a wide-bandgap perovskite heterojunction ultraviolet optoelectronic synapse device. Background Art

[0002] Neurosynaptic devices are artificial devices inspired by biological synapses, designed to mimic their functionality and achieve information processing and storage capabilities similar to those of the human brain. As a core component of neuromorphic computing, they simulate synaptic plasticity to enable efficient, low-power parallel computing, such as long-term potentiation (LTP) and long-term depression (LTD). Neurosynaptic devices are expected to replace traditional von Neumann architectures, enabling intelligent processing with integrated storage and computing, high parallelism, and low power consumption. The analog nature of neurosynaptic devices naturally enables online updates of neural network weights, avoiding the frequent data transfer required by traditional GPUs and significantly reducing energy consumption. They can also be used in IoT devices to process sensor data in real time and adapt to environmental changes, as well as to simulate preprocessing capabilities of biological senses.

[0003] Ultraviolet photosynaptic devices (UVPSDs) are a type of artificial synaptic device that utilizes UV light to modulate synaptic plasticity, mimicking the weight-regulating function of biological synapses through optical signals. These devices combine the strengths of optoelectronics and neuromorphic computing, demonstrating unique importance in specific applications. These devices typically utilize UV-sensitive materials, such as oxide semiconductors and wide-bandgap perovskites, whose conductivity or polarization state can be modulated by UV light. By varying the wavelength, intensity, or pulse timing of UV light, the device state can be altered to mimic the short-term plasticity (STP) and long-term plasticity (LTP / LTD) of biological synapses. UVPSDs can achieve efficient integrated computing and storage by simulating the neuronal and synaptic functions of the human brain. These devices are capable of handling complex information processing tasks, particularly under high-computing demands, while significantly reducing energy consumption. UVPSDs can also integrate optical sensing and artificial synaptic functions to mimic the perception, processing, and memory processes of the human visual system. These devices have important applications in machine vision systems, improving the efficiency and accuracy of information processing while reducing power consumption.

[0004] By constructing a wide-bandgap perovskite / organic semiconductor heterojunction and utilizing the matching energy bands of the two types of materials to achieve selective transport of photogenerated charges, it is expected that high-performance ultraviolet photoelectric synaptic devices will be realized. However, due to the high LUMO energy level of the wide-bandgap perovskite, which is usually higher than the LUMO energy level of the organic semiconductor material used as the hole transport layer, the photogenerated electrons and holes generated in the wide-bandgap perovskite can be simultaneously injected into the hole transport layer, resulting in a high carrier recombination rate. In addition, the recombination of photogenerated electrons and holes within the wide-bandgap perovskite is also relatively intense. These two factors make it difficult for wide-bandgap perovskite / organic semiconductor heterojunctions to achieve photoelectric synaptic functions or the device performance is poor, making it difficult to meet the needs of practical applications. Summary of the Invention

[0005] The present invention aims to avoid the shortcomings of the above-mentioned prior art and provide a method for improving the performance of wide-bandgap perovskite heterojunction ultraviolet photoelectric synaptic devices, so as to effectively improve the performance of ultraviolet photoelectric synaptic devices by enhancing the electron capture ability through B3PyMPM doping.

[0006] The present invention adopts the following technical solutions to solve the technical problems:

[0007] The present invention first provides a method for improving the performance of a wide-bandgap perovskite heterojunction ultraviolet photoelectric synapse device. The method is characterized in that: the ultraviolet photoelectric synapse device realizes the ultraviolet photoelectric synapse function through a heterojunction composed of a PEDOT:PSS (poly (3,4-ethylenedioxythiophene / polystyrene sulfonate)) hole transport layer and a wide-bandgap perovskite PEA2PbCl4 film. By doping the PEA2PbCl4 film with B3PyMPM (4,6-bis(3,5-di(3-pyridyl)phenyl)-2-methylpyrimidine), the electron capture ability is enhanced, carrier recombination is reduced, efficient separation and transmission of photogenerated carriers are achieved, the decrease amplitude of photocurrent is reduced, and the duration of photocurrent is increased, thereby improving the performance of the ultraviolet photoelectric synapse device.

[0008] Furthermore, a method for preparing a B3PyMPM-doped PEA2PbCl4 perovskite film comprises adding B3PyMPM to a perovskite precursor solution for preparing a PEA2PbCl4 film and mixing them uniformly to obtain a doping solution, and then spin-coating the doping solution onto a substrate to form a thin film, thereby obtaining a B3PyMPM-doped PEA2PbCl4 film, referred to as a PEA2PbCl4-B3PyMPM film. The concentration of B3PyMPM in the doping solution is 0.5 wt% to 1.5 wt%.

[0009] Based on the above method, the present invention also provides a PEA2PbCl4-B3PyMPM film / PEDOT:PSS heterojunction ultraviolet photoelectric synapse device, whose structure is: an insulating substrate is used as the base region of the ultraviolet photoelectric synapse device; a PEDOT:PSS hole transport layer is arranged on the upper surface of the insulating substrate; a PEA2PbCl4-B3PyMPM film is laid on the PEDOT:PSS hole transport layer, and the PEA2PbCl4-B3PyMPM film forms a heterojunction with the PEDOT:PSS hole transport layer; and a metal electrode is arranged on the PEA2PbCl4-B3PyMPM film.

[0010] Furthermore, in the constructed device, the thickness of the PEDOT:PSS hole transport layer is 30-100 nm, the thickness of the PEA2PbCl4-B3PyMPM film is 100-300 nm, and the metal electrode is an Ag electrode with a thickness of 60-100 nm.

[0011] The method for preparing the PEA2PbCl4-B3PyMPM film / PEDOT:PSS heterojunction ultraviolet photoelectric synaptic device of the present invention can be carried out according to the following steps:

[0012] (1) Clean the insulating substrate (such as silicon oxide wafer, insulating glass) with deionized water, alcohol, and acetone ultrasonically in sequence, and blow dry with nitrogen;

[0013] (2) covering a portion of the upper surface of the insulating substrate with a PEDOT:PSS hole transport layer by a spin coating method;

[0014] (3) preparing a perovskite precursor solution containing B3PyMPM, and then spin-coating it on the hole transport layer to form a PEA2PbCl4-B3PyMPM film;

[0015] (4) A metal electrode is provided on the PEA2PbCl4-B3PyMPM film by using a method such as thermal evaporation, thereby obtaining a PEA2PbCl4-B3PyMPM film / PEDOT:PSS heterojunction ultraviolet photoelectric synapse device.

[0016] Compared with the prior art, the beneficial effects of the present invention are embodied in:

[0017] 1. The PEA2PbCl4-B3PyMPM film / PEDOT:PSS heterojunction ultraviolet photoelectric synaptic device in the present invention can utilize the high absorption rate of wide-bandgap perovskite to ultraviolet light, and combine the advantages of B3PyMPM doping to increase electron capture ability, thereby improving the absorption efficiency of detection light and the separation and transmission efficiency of photogenerated carriers.

[0018] 2. The PEA2PbCl4-B3PyMPM film and the PEDOT:PSS hole transport layer in the ultraviolet photoelectric synaptic device of the present invention can be prepared by spin coating, which is a simple process, avoids expensive instruments and equipment, and reduces the cost of device preparation.

[0019] 3. The PEA2PbCl4-B3PyMPM film / PEDOT:PSS heterojunction ultraviolet photoelectric synaptic device of the present invention can operate at a low bias voltage and consume only a small amount of external energy, thereby effectively reducing power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic structural diagram of the PEA2PbCl4-B3PyMPM film / PEDOT:PSS heterojunction ultraviolet photoelectric synapse device of the present invention, in which the following numbers are marked: 1 is an insulating substrate; 2 is a PEDOT:PSS hole transport layer; 3 is a PEA2PbCl4-B3PyMPM film; and 4 is an Ag electrode.

[0021] Figure 2 Schematic diagram of the energy bands of B3PyMPM, PEA2PbCl4 and PEDOT:PSS.

[0022] Figure 3 The UV photoelectric synaptic devices with different B3PyMPM doping concentrations prepared in Example 1 of the present invention were subjected to a bias voltage of 0.1 V at a wavelength of 265 nm, a pulse time of 3 s, and an intensity of 0.81 mW / cm 2 Time response curve under UV light.

[0023] Figure 4 The UV photoelectric synaptic devices with different B3PyMPM doping concentrations prepared in Example 1 of the present invention were subjected to a bias voltage of 0.1 V at a wavelength of 265 nm, a pulse time of 3 s, and an intensity of 0.81 mW / cm 2 STP response curve under ultraviolet light. In the figure, A1 is the excitatory postsynaptic current stimulated by the first light pulse, and A2 is the excitatory postsynaptic current stimulated by the second light pulse.

[0024] Figure 5 The UV photoelectric synaptic devices with different B3PyMPM doping concentrations prepared in Example 1 of the present invention were subjected to a bias voltage of 0.1 V at a wavelength of 265 nm, a pulse time of 3 s, and an intensity of 0.81 mW / cm 2 Paired pulse facilitation PPF exponential fitting curve under ultraviolet light.

[0025] Figure 6The ultraviolet photoelectric synaptic device with a B3PyMPM doping concentration of 1.5 wt% prepared in Example 1 of the present invention was irradiated with ultraviolet light of wavelengths of 254 nm, 265 nm, 300 nm, and 365 nm (pulse time of 3 s and intensity of 0.81 mW / cm 2 ) time response curve under .

[0026] Figure 7 The ultraviolet photoelectric synaptic device with a B3PyMPM doping concentration of 1.5 wt% prepared in Example 1 of the present invention has a bias voltage of 0.1 V and an intensity of 0.95 mW / cm 2 , 1.18mW / cm 2 , 2.21mW / cm 2 、3.24mW / cm 2 、3.95mW / cm 2 LTP response curves under ultraviolet light (the wavelength is 265nm, the pulse time is 1s, and the number of pulses is 1).

[0027] Figure 8 The ultraviolet photoelectric synaptic device with a B3PyMPM doping concentration of 1.5 wt% prepared in Example 1 of the present invention was irradiated with ultraviolet light (wavelength of 265 nm, intensity of 3.95 mW / cm2) with a bias voltage of 0.1 V and pulse durations of 0.5 s, 1 s, 2 s, and 3 s, respectively. 2 , the number of pulses is 1).

[0028] Figure 9 The ultraviolet photoelectric synaptic device with a B3PyMPM doping concentration of 1.5 wt% prepared in Example 1 of the present invention was irradiated with ultraviolet light (wavelength of 265 nm, intensity of 3.95 mW / cm) at a bias voltage of 0.1 V and pulse numbers N of 10, 20, 30, 40, and 50, respectively. 2 LTP response curve under the condition of 0.5s pulse time. DETAILED DESCRIPTION

[0029] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is provided in conjunction with the following embodiments. The following is merely an example and illustration of the concept of the present invention. Any modification, supplement, or substitution of the described specific embodiments by a person skilled in the art, as long as it does not deviate from the concept of the invention or exceed the scope defined by the claims, shall fall within the scope of protection of the present invention.

[0030] Example 1

[0031] like Figure 1As shown, the structure of the PEA2PbCl4-B3PyMPM film / PEDOT:PSS heterojunction ultraviolet photoelectric synapse device in this embodiment is as follows: an insulating substrate 1 is used as the base region of the ultraviolet photoelectric synapse device; a PEDOT:PSS hole transport layer 2 is covered on a part of the upper surface of the insulating substrate 1, and the boundary of the PEDOT:PSS hole transport layer 2 does not exceed the boundary of the insulating substrate 1; a PEA2PbCl4-B3PyMPM film 3 is laid on the upper surface of the PEDOT:PSS hole transport layer 2, and the PEA2PbCl4-B3PyMPM film 3 forms a heterojunction with the PEDOT:PSS hole transport layer 2; and a pair of Ag electrodes 4 are set on a part of the upper surface of the PEA2PbCl4-B3PyMPM film 3.

[0032] Specifically, the insulating substrate 1 is a 500 μm thick glass substrate. The PEDOT:PSS hole transport layer 2 has a thickness of 100 nm. The PEA2PbCl4-B3PyMPM film 3 has a thickness of 300 nm. The Ag electrode 4 has a thickness of 80 nm.

[0033] The preparation method of the PEA2PbCl4-B3PyMPM film / PEDOT:PSS heterojunction ultraviolet photoelectric synaptic device in this embodiment is carried out according to the following steps:

[0034] (1) A glass substrate with an area of 1.5 cm × 1.5 cm was used as an insulating substrate and ultrasonically cleaned with deionized water, alcohol, and acetone for 10 minutes each, and then blown dry with nitrogen.

[0035] (2) A PEDOT:PSS hole transport layer is covered on a portion of the upper surface of the insulating substrate by a spin coating method.

[0036] (3) 0.1261 g PEACl, 0.1112 g PbCl2, and different masses of B3PyMPM (doping concentrations of 0.5 wt%, 1 wt%, and 1.5 wt%, respectively, where the doping concentration is the ratio of the mass of B3PyMPM to the total mass of PEACl and PbCl2) were added to 1 mL of a 3:2 volume ratio DMF / DMSO mixture. The mixture was stirred at 40 °C for 5 h to complete the reaction, thereby obtaining PEA2PbCl4-B3PyMPM mixed solutions with different doping concentrations. The obtained mixed solution was filtered with a filter disc and then spin-coated on the PEDOT:PSS hole transport layer at 3000 rpm for 30 s. After 20 s of spin-coating, the anti-solvent ethyl acetate was added dropwise, and then annealed on a hot plate at 100 °C for 15 min to obtain a PEA2PbCl4-B3PyMPM film.

[0037] (4) A pair of Ag electrodes were set on the PEA2PbCl4-B3PyMPM film by thermal evaporation method to obtain a PEA2PbCl4-B3PyMPM film / PEDOT:PSS heterojunction UV photoelectric synapse device.

[0038] The energy band diagram of B3PyMPM, PEA2PbCl4 and PEDOT:PSS in the PEA2PbCl4-B3PyMPM film / PEDOT:PSS heterojunction UV photoelectric synaptic device prepared in this example is shown in FIG. Figure 2 As shown in the figure, it can be seen that this heterostructure has reasonable band matching.

[0039] The time response curves of the UV photoelectric synaptic devices with different B3PyMPM doping concentrations prepared in this example are shown in FIG. Figure 3 As shown in the figure, the photoelectric response performance of the UV photoelectric synaptic device is significantly improved with increasing B3PyMPM doping concentration. As the B3PyMPM doping concentration increases from 0wt%, 0.5wt%, 1wt% to 1.5wt%, the postsynaptic current of the UV photoelectric synaptic device increases from 2.1nA, 4.1nA, 6.3nA to 8.3nA. In addition, the prepared PEA2PbCl4-B3PyMPM film / PEDOT:PSS heterojunction UV photoelectric synaptic device can operate normally at low bias voltage, which can effectively reduce device power consumption.

[0040] The STP response curves of the UV photoelectric synaptic devices with different B3PyMPM doping concentrations prepared in this example are shown in FIG. Figure 4 As shown in the figure, it can be seen that with the increase of B3PyMPM doping concentration, the photoelectric response performance of the ultraviolet photoelectric synaptic device is significantly improved. As the B3PyMPM doping concentration increases from 0wt%, 0.5wt%, 1wt% to 1.5wt%, the paired pulse facilitation PPF of the ultraviolet photoelectric neural synaptic device increases from 122%, 134%, 146% to 154%.

[0041] The PPF fitting curves of the UV photoelectric synaptic devices with different B3PyMPM doping concentrations prepared in this example are shown in Figure 2. Figure 5 As shown in the figure, it can be seen that with the increase of B3PyMPM doping concentration, the photoelectric response performance of the ultraviolet photoelectric synaptic device is significantly improved. As the B3PyMPM doping concentration increases from 0wt%, 0.5wt%, 1 wt% to 1.5wt%, the paired pulse facilitation (PPF) fitting curve of the ultraviolet photoelectric synaptic device gradually increases.

[0042] The time response curves of the ultraviolet photoelectric synaptic device with a B3PyMPM doping concentration of 1.5 wt% prepared in this example to ultraviolet light of different wavelengths are shown in FIG. Figure 6As shown in the figure, it can be seen that the device has good photoelectric response performance to ultraviolet light.

[0043] See also Figure 7 、 Figure 8 、 Figure 9 The LTP response curve of the ultraviolet photoelectric synaptic device with a B3PyMPM doping concentration of 1.5wt% prepared in this example to different light intensities, light pulse durations and light pulse numbers shows that the device exhibits good LTP response with the increase of light intensity, the increase of light pulse duration and the increase of light pulse number.

[0044] From the above, it can be seen that the present invention enhances the electron capture ability by doping B3PyMPM as an electron capture site in the wide bandgap perovskite film, realizes the effective separation of photogenerated electrons and holes in physical space and reduces carrier recombination, thereby increasing the photocurrent amplitude and increasing the photocurrent duration, and improving the performance of ultraviolet photoelectric synaptic devices.

[0045] The above are merely exemplary embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for improving the performance of a wide-bandgap perovskite heterojunction ultraviolet photoelectric synapse device, characterized in that: The ultraviolet photoelectric synaptic device realizes the ultraviolet photoelectric neural synaptic function through a heterojunction composed of a PEDOT:PSS hole transport layer and a wide-bandgap perovskite PEA2PbCl4 film. By doping the PEA2PbCl4 film with B3PyMPM, the electron capture ability is enhanced, thereby improving the performance of the ultraviolet photoelectric synaptic device.

2. The method according to claim 1, characterized in that The preparation method of B3PyMPM-doped PEA2PbCl4 film is as follows: B3PyMPM is added to the perovskite precursor solution for preparing the PEA2PbCl4 film and mixed evenly to obtain a doping solution, and the doping solution is prepared into a film on a substrate by spin coating, thereby obtaining a B3PyMPM-doped PEA2PbCl4 film, which is recorded as PEA2PbCl4-B3PyMPM film.

3. The method according to claim 2, wherein: In the doping solution, the concentration of B3PyMPM is 0.5 wt %-1.5 wt %.

4. A PEA2PbCl4-B3PyMPM film / PEDOT:PSS heterojunction ultraviolet photoelectric synapse device obtained according to the method of any one of claims 1 to 3.

5. The PEA2PbCl4-B3PyMPM film / PEDOT:PSS heterojunction ultraviolet photoelectric synapse device according to claim 4, characterized in that: The structure is: An insulating substrate is used as the base region of an ultraviolet photoelectric synaptic device; a PEDOT:PSS hole transport layer is arranged on the upper surface of the insulating substrate; a PEA2PbCl4-B3PyMPM film is laid on the PEDOT:PSS hole transport layer, and the PEA2PbCl4-B3PyMPM film forms a heterojunction with the PEDOT:PSS hole transport layer; and a metal electrode is arranged on the PEA2PbCl4-B3PyMPM film.

6. The ultraviolet optoelectronic synapse device according to claim 5, characterized in that: The thickness of the PEDOT:PSS hole transport layer is 30-100 nm.

7. The ultraviolet optoelectronic synapse device according to claim 5, characterized in that: The thickness of the PEA2PbCl4-B3PyMPM film is 100-300nm.

8. The ultraviolet optoelectronic synapse device according to claim 5, characterized in that: The metal electrode is an Ag electrode with a thickness of 60-100 nm.

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