A perovskite heterojunction blue-violet narrowband photosynapse and its application

Abstract

This invention belongs to the field of optoelectronic devices and discloses a perovskite heterojunction blue-violet narrowband photosynapse and its application. The device uses a heterojunction composed of a poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) hole-conducting layer and a perovskite thin film as its functional unit to achieve blue-violet narrowband photosynaptic function. By optimizing the thickness of the PTAA hole-conducting layer to suppress the short-wavelength ultraviolet light response, and by controlling the halogen atom type and ratio of the perovskite thin film to optimize the light absorption range of the film, the device generates a narrowband synaptic response only in the blue-violet light band with wavelengths in the range of 380nm to 490nm, thus realizing the blue-violet narrowband photosynaptic function. The device of this invention combines excellent blue-violet narrowband response, stable synaptic plasticity, and high anti-interference capability, exhibiting excellent performance in fields such as fingerprint recognition and possessing outstanding practical value.

Description

Technical Field

[0001] This invention belongs to the field of optoelectronic devices and relates to an optoelectronic device that generates electrical energy by converting blue-violet light, specifically a perovskite heterojunction blue-violet narrowband photosynapse and its application. Background Technology

[0002] Synaptic devices are fundamental units that simulate the synaptic connections and information transmission mechanisms between neurons in biological neural systems, and are key components for realizing next-generation neuromorphic computing. In biological neural systems, synapses store and learn information by adjusting synaptic weights; correspondingly, artificial synaptic devices can reversibly regulate their conductance or current state under external stimuli, thereby simulating synaptic plasticity. These devices typically achieve dynamic adjustment of synaptic weights and non-volatile memory functions through electrical signals, optical signals, or a combination of both, enabling the learning, memory, and perception processes of neural networks to be directly implemented at the hardware level. Compared to traditional computing systems based on the von Neumann architecture, synaptic devices integrate storage and computation functions into a single device, effectively avoiding the "memory wall" problem caused by frequent data transfer between storage and processing units, thus offering significant advantages in power consumption, computational efficiency, and parallel processing capabilities.

[0003] As research deepens, the spectral response characteristics of photoelectric synapses have gradually attracted widespread attention. Traditional photoelectric synaptic devices mostly employ broadband photosensitive materials or structural designs, enabling responses to light stimuli across a wide wavelength range and achieving light-induced synaptic plasticity modulation. However, broadband photoelectric synapses exhibit poor spectral selectivity, making it difficult to effectively distinguish incident light signals of different wavelengths. They are also susceptible to interference from multi-wavelength light sources and ambient light, leading to decreased signal recognition accuracy and limiting their application in high-precision optical information processing and multi-channel optical neural networks. In contrast, narrowband photoelectric synapses, by introducing spectral selectivity modulation mechanisms into material systems, band structures, and device design, respond only to light signals in specific wavelength bands and exhibit a significant suppression effect on light stimuli in other wavelength bands. These devices possess high spectral selectivity, low noise interference, and excellent signal discrimination capabilities, enabling wavelength-based optical information encoding and processing. They demonstrate unique advantages in multispectral sensing computing, color recognition, and biomimetic vision systems. Therefore, narrowband photoelectric synapses hold significant research importance and application potential in constructing highly selective, multi-channel optical neural networks and artificial visual perception systems.

[0004] Research on narrowband photoelectric synapses is still in its early stages, with limited related reports. Previous studies on narrowband photoresponse have primarily focused on the design of narrowband photodetectors. Traditional narrowband optoelectronic devices typically employ bandpass filters to shield interfering light signals and are paired with broadband detectors to detect target light. However, the complex device structure results in large system size, low integration, and inconvenience in use. To achieve filterless operation and high integration, researchers have recently developed narrowband optoelectronic devices based on carrier collection narrowing mechanisms, periodic nanostructures, semiconductor guided modes, and optical microcavity resonances. However, these methods still suffer from complex fabrication, limited tunability of response bands, insufficient stability, and low photoelectric conversion efficiency. For narrowband photoelectric synapses, balancing narrowband spectral selectivity with low power consumption and achieving stable and tunable synaptic weights remains a core challenge; therefore, realizing high-performance, low-power, and highly stable narrowband photoelectric synapses remains a significant challenge in this field. Summary of the Invention

[0005] Based on the shortcomings of the existing technology, this invention provides a perovskite heterojunction blue-violet narrowband photoelectric synapse and its application. It aims to suppress the short-wavelength ultraviolet light response and enhance the specific absorption capability of blue-violet light by optimizing the hole conduction layer thickness and regulating the composition of perovskite halogen atoms, thereby realizing the construction of a high-performance blue-violet narrowband photoelectric synapse.

[0006] The present invention adopts the following technical solution to solve the technical problem: This invention first proposes a method for performance modulation of a perovskite heterojunction blue-violet narrowband photosynapse. Its key feature is that a heterojunction composed of a poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA) hole-conducting layer and a perovskite thin film is used as the functional unit. By optimizing the thickness of the hole-conducting layer, the light response in the short-wavelength ultraviolet band with wavelengths <375nm is suppressed. Simultaneously, by adjusting the halogen atom ratio of the perovskite thin film, the light absorption range of the film is optimized, enabling the device to generate a narrowband synaptic response only in the blue-violet light band with wavelengths in the range of 380nm~490nm, thereby realizing the function of a blue-violet narrowband photosynapse.

[0007] Specifically, this invention achieves synergistic effects through "optimized hole conduction layer thickness + precise control of perovskite halogen composition": On the one hand, the PTAA hole conduction layer thickness is optimized to 100nm~200nm, ensuring efficient hole transport while selectively absorbing and blocking short-wavelength ultraviolet light with wavelengths <375nm, preventing ultraviolet light from reaching the perovskite active layer and generating photogenerated carriers in non-target wavelength bands, thus suppressing non-target wavelength band light interference at the source. On the other hand, the perovskite thin film is limited to PEA2PbBr x I y Thin film (x = 2.5~4, y = 0~1.5, x+y=4) or PEA2PbCl sBr t Thin films (s = 0–0.5, t = 3.5–4, s+t = 4) optimize the band structure and light absorption characteristics of perovskite materials through precise control of halogen components, significantly enhancing their specific absorption capability in the 380 nm–490 nm blue-violet light band and greatly improving blue-violet light response efficiency. The combination of these two technologies achieves precise control of heterojunction interface band matching, light absorption, and non-target wavelength light blocking, enabling the device to possess the excellent characteristics of "nearly no response to short-wavelength ultraviolet light and highly efficient and specific response to blue-violet light," thus achieving a balance between narrowband response and synaptic performance.

[0008] Based on the above performance regulation method, the present invention further provides a perovskite heterojunction blue-violet narrowband photosynapse, the device structure of which is as follows: a transparent insulating substrate is used as the substrate; a PTAA hole conducting layer is disposed on the upper surface of the substrate; a perovskite thin film is disposed on the PTAA hole conducting layer, the perovskite thin film and the PTAA hole conducting layer form a heterojunction; and a metal electrode is disposed on the perovskite thin film.

[0009] As a further optimization of the present invention, the optimal parameters for each functional layer were determined through extensive experimental screening as follows: The thickness of the perovskite film is optimized to be 200nm~400nm, which can ensure sufficient absorption of blue light and effective generation of photogenerated carriers. The metal electrode is a Ni electrode with a thickness of 80nm~100nm, which has excellent interfacial contact characteristics with the perovskite layer.

[0010] To achieve low-cost, large-scale fabrication of the aforementioned devices, this invention also provides a perovskite heterojunction blue-violet narrowband photosynapse, comprising the following steps: (1) The transparent insulating substrate was ultrasonically cleaned with deionized water, ethanol and acetone in sequence, dried with nitrogen, and then treated with ultraviolet ozone. (2) A PTAA hole-conducting layer is prepared on the upper surface of the transparent insulating substrate by spin coating; (3) Prepare a perovskite precursor solution, spin-coat it onto the PTAA hole conduction layer, and anneal it to form a perovskite film; (4) A metal electrode is prepared on the perovskite film by thermal evaporation to obtain the perovskite heterojunction blue-violet narrowband photosynapse.

[0011] The perovskite heterojunction blue-violet narrowband photoelectric synapse described in this invention shows broad application prospects in the field of fingerprint recognition. Specifically, this invention is based on PEA2PbBr 3.5 I 0.5 The photoelectric synapse constructed from a thin film / PTAA (120nm) heterostructure exhibits excellent fingerprint recognition performance.

[0012] The core principle of fingerprint recognition is based on the difference in optical properties between the fingerprint ridges (rich in sebum) and the background (fingerprint valleys and surrounding areas). Sebum-rich fingerprint ridges contain proteins, lipids, and their oxidation products, absorbing most of the incident deep ultraviolet light and emitting 330nm ultraviolet fluorescence and 440nm blue fluorescence under deep ultraviolet light excitation. The background area, however, only reflects deep ultraviolet light and does not produce the aforementioned fluorescence. During recognition, synaptic devices sense the light signals from the fingerprint ridges (emitted ultraviolet and blue fluorescence) and the background (reflected deep ultraviolet light) under deep ultraviolet light stimulation and convert them into synaptic currents. The difference in current between the two directly determines the recognition accuracy. Narrow-band photoelectric synaptic devices only respond to the blue fluorescence emitted by the fingerprint ridge area and are unresponsive to non-target wavelengths such as deep ultraviolet, ultraviolet light, and ambient light, significantly enhancing the contrast between the fingerprint ridges and the background and ensuring high recognition accuracy. Broadband photoelectric synapses, on the other hand, are susceptible to interference from non-target wavelengths, reducing contrast and lowering the recognition rate.

[0013] Compared with existing technologies, the beneficial effects of this invention are reflected in: 1. This invention enables devices to achieve excellent narrowband response in the 380nm~490nm blue-violet light band with a full width at half maximum (FWHM) of only 18nm~51nm by simply optimizing the thickness of the PTAA hole conduction layer and adjusting the type and ratio of perovskite halogens. It eliminates the need for thick film structures with traditional charge collection narrowing mechanisms, avoids the problems of complex single-crystal fabrication processes, high costs, and poor film uniformity, simplifies the fabrication process, and significantly improves the repeatability and stability of the devices.

[0014] 2. The blue-violet light narrowband photoelectric synapse structure of the present invention is simple and can be prepared by conventional spin coating method. It does not require a complex vacuum system or high-cost equipment. While achieving blue-violet light narrowband response and stable synaptic plasticity, it greatly reduces process complexity and manufacturing cost, making it suitable for large-scale preparation.

[0015] 3. The device of the present invention has excellent energy efficiency, can achieve efficient synaptic response at a low bias voltage, and has extremely low energy consumption. It can significantly reduce the system operating power consumption while ensuring good optoelectronic performance and narrowband selectivity, and is suitable for low power consumption application scenarios.

[0016] 4. This invention is based on PEA2PbBr 3.5 I 0.5 The photoelectric synapse constructed from a thin film / PTAA (120nm) heterostructure combines excellent narrowband response to blue and violet light, stable synaptic plasticity, and high anti-interference capability. It exhibits excellent recognition accuracy in fingerprint recognition applications and has outstanding practical value. Attached Figure Description

[0017] Figure 1 The present invention is PEA2PbBr3.5 I 0.5 A schematic diagram of a blue narrowband synaptic device with a thin film and PTAA heterojunction. In the diagram, the numbers are: 1 is a transparent insulating substrate; 2 is a PTAA hole conducting layer; 3 is a perovskite thin film; and 4 is a Ni electrode.

[0018] Figure 2 PEA2PbBr 3.5 I 0.5 A schematic diagram of the band structure of PTAA.

[0019] Figure 3 The light transmittance of PTAA with different thicknesses (40nm, 80nm, 100nm, 120nm).

[0020] Figure 4 The light transmittance curve of the PTAA (120 nm) thin film prepared in Example 1 of the present invention and the absorption spectra of perovskite thin films with different halogen element ratios in Examples 1 and 2 are shown.

[0021] Figure 5 The PEA2PbBr prepared in Example 1 of this invention 3.5 I 0.5 Thin-film / PTAA (120nm) heterojunction blue-violet narrowband synapse at 2V bias voltage, 0.5s pulse time and 8.3μW / cm 2 Time response curves under different wavelengths (360nm~490nm wavelength range) of monochromatic light irradiation at different light intensities.

[0022] Figure 6 The PEA2PbBr prepared in Example 1 of this invention 3.5 I 0.5 Thin-film / PTAA (120nm) heterojunction blue-violet narrowband synapse at 2V bias voltage, 0.5s pulse time and 8.3μW / cm 2 The spectral response in the wavelength range of 360nm to 490nm under light intensity, with a full width at half maximum (FWHM) of 44nm.

[0023] Figure 7 The PEA2PbBr prepared in Example 1 of this invention 3.5 I 0.5 Thin-film / PTAA (100nm) heterojunction photosynapse at 2V bias voltage, 0.5s pulse time and 8.3μW / cm 2 Time response curves under different wavelengths (360nm~490nm wavelength range) of monochromatic light irradiation at different light intensities.

[0024] Figure 8 The PEA2PbBr prepared in Example 1 of this invention 3.5 I0.5 Thin-film / PTAA (100nm) heterojunction photosynapse at 2V bias voltage, 0.5s pulse time and 8.3μW / cm 2 The spectral response in the wavelength range of 360nm to 490nm under light intensity, with a full width at half maximum (FWHM) of 47nm.

[0025] Figure 9 The PEA2PbBr prepared in Example 1 of this invention 3.5 I 0.5 Thin-film / PTAA (80nm) heterojunction photosynapse at 2V bias voltage, 0.5s pulse time and 8.3μW / cm 2 Time response curves under different wavelengths (360nm~490nm wavelength range) of monochromatic light irradiation at different light intensities.

[0026] Figure 10 The PEA2PbBr prepared in Example 1 of this invention 3.5 I 0.5 Thin-film / PTAA (80nm) heterojunction photosynapse at 2V bias voltage, 0.5s pulse time and 8.3μW / cm 2 The spectral response in the wavelength range of 360nm to 490nm under light intensity, with a full width at half maximum (FWHM) of 45nm.

[0027] Figure 11 The PEA2PbBr prepared in Example 1 of this invention 3.5 I 0.5 Thin-film / PTAA (40nm) heterojunction photosynapse at 2V bias voltage, 0.5s pulse time and 8.3μW / cm 2 Time response curves under different wavelengths (360nm~490nm wavelength range) of monochromatic light irradiation at different light intensities.

[0028] Figure 12 The PEA2PbBr prepared in Example 1 of this invention 3.5 I 0.5 Thin-film / PTAA (40nm) heterojunction photosynapse at 2V bias voltage, 0.5s pulse time and 8.3μW / cm 2 The spectral response in the wavelength range of 360nm to 495nm under light intensity, with a full width at half maximum (FWHM) of 51nm.

[0029] Figure 13 The PEA2PbBr3I thin film / PTAA (120nm) heterojunction photosynapse prepared in Example 2 of this invention, under a bias voltage of 2V, a pulse time of 0.5s, and a power consumption of 8.3μW / cm², exhibited the following properties: 2Time response curves under different wavelengths (360nm~490nm wavelength range) of monochromatic light irradiation at different light intensities.

[0030] Figure 14 The PEA2PbBr3I thin film / PTAA (120nm) heterojunction photosynapse prepared in Example 2 of this invention, under a bias voltage of 2V, a pulse time of 0.5s, and a power consumption of 8.3μW / cm², exhibited the following properties: 2 The spectral response in the wavelength range of 360nm to 490nm under light intensity, with a full width at half maximum (FWHM) of 46nm.

[0031] Figure 15 The PEA2PbBr prepared in Example 2 of this invention 2.5 I 1.5 Thin-film / PTAA (120nm) heterojunction photosynapse at 2V bias voltage, 0.5s pulse time and 8.3μw / cm 2 Time response curves under different wavelengths (360nm~490nm wavelength range) of monochromatic light irradiation at different light intensities.

[0032] Figure 16 The PEA2PbBr prepared in Example 2 of this invention 2.5 I 1.5 Thin-film / PTAA (120nm) heterojunction photosynapse at 2V bias voltage, 0.5s pulse time and 8.3μW / cm 2 The spectral response in the wavelength range of 360nm to 490nm under light intensity, with a full width at half maximum (FWHM) of 49nm.

[0033] Figure 17 The PEA2PbBr4 thin film / PTAA (120nm) heterojunction photosynapse prepared in Example 2 of this invention, under a bias voltage of 2V, a pulse time of 0.5s, and a power consumption of 8.3μW / cm², exhibited the following properties: 2 Time response curves under different wavelengths (360nm~490nm wavelength range) of monochromatic light irradiation at different light intensities.

[0034] Figure 18 The PEA2PbBr4 thin film / PTAA (120nm) heterojunction photosynapse prepared in Example 2 of this invention, under a bias voltage of 2V, a pulse time of 0.5s, and a power consumption of 8.3μW / cm², exhibited the following properties: 2 The spectral response in the wavelength range of 360nm to 490nm under light intensity, with a full width at half maximum (FWHM) of 23nm.

[0035] Figure 19 The PEA2PbCl prepared in Example 2 of this invention 0.25 Br 3.75Thin-film / PTAA (120nm) heterojunction photosynapse at 2V bias voltage, 0.5s pulse time and 8.3μW / cm 2 Time response curves under different wavelengths (360nm~490nm wavelength range) of monochromatic light irradiation at different light intensities.

[0036] Figure 20 The PEA2PbCl prepared in Example 2 of this invention 0.25 Br 3.75 Thin-film / PTAA (120nm) heterojunction photosynapse at 2V bias voltage, 0.5s pulse time and 8.3μW / cm 2 The spectral response in the wavelength range of 360nm to 490nm under light intensity, with a full width at half maximum (FWHM) of 20nm.

[0037] Figure 21 The PEA2PbCl prepared in Example 2 of this invention 0.5 Br 3.5 Thin-film / PTAA (120nm) heterojunction photosynapse at 2V bias voltage, 0.5s pulse time and 8.3μW / cm 2 Time response curves under different wavelengths (360nm~490nm wavelength range) of monochromatic light irradiation at different light intensities.

[0038] Figure 22 The PEA2PbCl prepared in Example 2 of this invention 0.5 Br 3.5 Thin-film / PTAA (120nm) heterojunction photosynapse at 2V bias voltage, 0.5s pulse time and 8.3μW / cm 2 The spectral response in the wavelength range of 360nm to 490nm under light intensity, with a full width at half maximum (FWHM) of 18nm.

[0039] Figure 23 PEA2PbBr in Embodiment 3 of the present invention 3.5 I 0.5 Time response curves of thin film / PTAA (120nm) heterojunction blue-violet narrowband synapses under single-pulse and double-pulse blue light excitation (wavelength 430nm, bias voltage 0.5V, pulse duration 0.5s, light intensity 0.43mW / cm²). 2 ).

[0040] Figure 24 PEA2PbBr in Embodiment 3 of the present invention 3.5 I 0.5 A thin-film / PTAA (120nm) heterojunction blue-violet narrowband synapse exhibits light intensity of 0.018mW / cm² under a bias voltage of 0.5V. 2 0.43mW / cm2 6.26mW / cm 2 13.09mW / cm 2 33.4mW / cm 2 The long-term plasticity (LTP) response curves under blue light illumination (wavelength 430nm, bias voltage 0.5V, pulse duration 0.5s, pulse number 1).

[0041] Figure 25 PEA2PbBr in Embodiment 3 of the present invention 3.5 I 0.5 A thin-film / PTAA (120nm) heterojunction blue-violet narrowband synapse exhibited an intensity of 0.43mW / cm² under blue light illumination (wavelength 430nm, bias voltage 0.5V) for pulse durations of 0.1s, 0.3s, 0.5s, and 1s. 2 The LTP response curves are shown in the figure, where the number of pulses is 1. STP represents short-term plasticity.

[0042] Figure 26 PEA2PbBr in Embodiment 3 of the present invention 3.5 I 0.5 A thin-film / PTAA (120nm) heterojunction blue-violet narrowband synapse exhibits an intensity of 0.43mW / cm² under a bias voltage of 0.5V and blue light illumination with pulse numbers N of 5, 10, 20, 30, and 40 (all wavelengths at 430nm and a bias voltage of 0.5V). 2 The LTP response curves under the condition that the pulse time is 0.5s.

[0043] Figure 27 The fingerprint recognition weight current in Example 3 was simulated by blue fluorescence signals emitted by fingerprint ridges using 430nm LED light and deep ultraviolet light signals reflected by fingerprint valleys using 265nm LED light, and the results were compared and analyzed.

[0044] Figure 28 This refers to the fingerprint recognition accuracy in Example 3 and its dynamic changes during the model training process.

[0045] Figure 29 The curve shows the change in the model training loss function in Example 3. Detailed Implementation

[0046] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, the specific embodiments of the present invention will be described in detail below with reference to examples. The following content is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the described specific embodiments or use similar methods to replace them, as long as they do not deviate from the inventive concept or exceed the scope defined by the present invention, and all such modifications or additions should fall within the protection scope of the present invention.

[0047] Example 1 like Figure 1 As shown, the device structure of the perovskite heterojunction blue-violet narrowband photosynapse provided in this embodiment is as follows: a transparent insulating substrate 1 is used as the substrate; a PTAA hole conducting layer 2 is disposed on the upper surface of the transparent insulating substrate 1, and the boundary of the PTAA hole conducting layer 2 does not exceed the boundary of the transparent insulating substrate 1; a perovskite thin film 3 is disposed on the upper surface of the PTAA hole conducting layer 2, and the perovskite thin film 3 and the PTAA hole conducting layer 2 form a heterojunction; a pair of Ni electrodes 4 are thermally evaporated in a portion of the upper surface of the perovskite thin film 3.

[0048] Specifically: the transparent insulating substrate 1 is made of float glass with a thickness of 1.1 mm. The PTAA hole-conducting layer 2 has a thickness of 120 nm. The perovskite film 3 is a 270 nm thick PEA2PbBr film. 3.5 I 0.5 Thin film. The thickness of Ni electrode 4 is 80 nm.

[0049] The blue light narrowband photosynapse in this embodiment is prepared according to the following steps: (1) The float glass was ultrasonically cleaned with deionized water, ethanol and acetone for 15 minutes in sequence, then dried in N2 flow, and finally treated with ultraviolet ozone for 20 minutes.

[0050] (2) Add different masses of PTAA powder to 1 mL of chlorobenzene to form PTAA solutions with concentrations of 15 mg / mL, 20 mg / mL, 30 mg / mL and 40 mg / mL respectively. Spin-coat the solutions onto the upper surface of float glass to form PTAA hole conduction layers with thicknesses of 40 nm, 80 nm, 100 nm and 120 nm respectively.

[0051] (3) To a mixture of 0.5 mL of N,N-dimethylformamide (DMF) / dimethyl sulfoxide (DMSO) (DMF to DMSO volume ratio of 3:2), add 80.8 mg PEABr, 55.05 mg PbBr2 and 23.05 mg PbI2 to prepare PEA2PbBr. 3.5 I 0.5Perovskite precursor solution. After filtration, the obtained perovskite precursor solution was spin-coated onto the PTAA hole-conducting layer at 3000 rpm for a total spin-coating time of 30 s. When the spin-coating reached 10 s, 110 μL of chlorobenzene antisolvent was dropped onto the film. After spin-coating, the film was annealed at 100 °C for 10 minutes.

[0052] (4) A pair of Ni electrodes are deposited on the perovskite film by thermal evaporation, thus obtaining a blue-violet narrowband photosynapse based on the perovskite film / PTAA heterojunction.

[0053] The PEA2PbBr in the blue-violet narrowband photosynapse prepared in this embodiment 3.5 I 0.5 The band structure diagram of PTAA is as follows: Figure 2 As shown in the figure, this heterostructure exhibits reasonable band matching. Specifically, PEA2PbBr 3.5 I 0.5 Under blue-violet light excitation, a large number of excitons are generated, which rapidly dissociate into electrons and holes. Due to PEA2PbBr 3.5 I 0.5 The highest occupied molecular orbital (HOMO) level of PEA2PbBr is much lower than that of PTAA, allowing photoexcitation-generated holes to be easily injected into the PTAA thin layer. These holes can then transport within the PTAA channels and be collected by electrodes when a bias voltage is applied. This process increases the hole density in the PTAA, thereby inducing a photocurrent. Simultaneously, photogenerated electrons remain trapped within PEA2PbBr. 3.5 I 0.5 This causes photogenerated electrons and holes to separate in space, thereby reducing the recombination rate of photogenerated carriers.

[0054] Figure 3 The figures show the light transmittance of PTAA films with different thicknesses (40nm, 80nm, 100nm, and 120nm). As can be seen from the figures, with increasing PTAA thickness, its blocking ability for the ultraviolet band with wavelengths <375nm significantly increases, while the transmittance continuously decreases. However, in the visible light and blue-violet light bands of 380nm~600nm, PTAA films of all thicknesses maintain high transmittance with minimal differences. Among them, the 100nm and 120nm thick PTAA films exhibit excellent ultraviolet-blue-violet light transmittance control effects: achieving efficient blocking of ultraviolet light while maintaining high transmittance in the target blue-violet light band of 380nm~490nm.

[0055] The PEA2PbBr prepared in this embodiment 3.5 I 0.5 The absorption spectrum of the thin film and the light transmittance curve of the PTAA (120nm) thin film are as follows: Figure 4As shown in the figure, the 120nm PTAA film has extremely low transmittance in the short-wave ultraviolet band (<375nm), effectively blocking ultraviolet light from reaching the perovskite active layer; while PEA2PbBr... 3.5 I 0.5 The thin film exhibits strong absorption characteristics in the blue-violet light band with wavelengths of 380nm to 470nm. The synergistic effect of these two characteristics ensures that the device only produces a narrow-band response to blue-violet light, providing a key optical basis for realizing synaptic functions that achieve ultraviolet suppression and high selectivity for blue-violet light.

[0056] The PEA2PbBr prepared in this embodiment 3.5 I 0.5 The time response curves of the thin film / PTAA (120nm) heterojunction blue-violet narrowband photosynapse under monochromatic light illumination of different wavelengths are shown below. Figure 5 As shown in the figure. The results show that the device has significant wavelength selectivity: when the incident light is in the short-wave ultraviolet band (wavelength <375nm), the photoelectric response current of the device is close to the baseline level, with almost no response; when the incident light wavelength is in the blue-violet band (about 380nm~480nm), the device generates obvious current pulse response, and reaches a peak near 430nm, exhibiting excellent blue light narrowband response characteristics.

[0057] The PEA2PbBr prepared in this embodiment 3.5 I 0.5 The spectral response characteristics of the thin film / PTAA (120nm) heterojunction blue-violet narrowband photosynapse are as follows: Figure 6 As shown in the figure. The test results show that the device only produces a significant photoelectric response in the blue-violet light band of 380nm~480nm, and the full width at half maximum (FWHM) of the response is only 44nm. This narrow-band response characteristic fully confirms the device's high selective recognition capability for blue-violet light.

[0058] The PEA2PbBr prepared in this embodiment 3.5 I 0.5 The time response curves of the thin film / PTAA (100nm) heterojunction photosynapse under monochromatic light illumination of different wavelengths are shown below. Figure 7 As shown. The results indicate that, compared with the optimal PEA2PbBr 3.5 I 0.5 Compared to the thin-film / PTAA (120nm) heterojunction blue-violet narrowband photosynapse, this device generates a slightly higher photocurrent when the incident light is in the short-wavelength ultraviolet band. This indicates that although the 100nm thick PTAA layer's filtering ability for short-wavelength ultraviolet light is not as good as the 120nm layer, it still possesses a good filtering effect. Its spectral response characteristics are as follows: Figure 8 As shown in the figure, the test results show that the device has a full width at half maximum (FWHM) of only 47nm, exhibiting excellent narrowband response characteristics.

[0059] The PEA2PbBr prepared in this embodiment 3.5 I 0.5 The time response curves of the thin film / PTAA (80nm) heterojunction photosynapse under monochromatic light irradiation at different wavelengths are shown below. Figure 9 As shown in the figure. The results indicate that when the incident light is in the short-wavelength ultraviolet band, the photoelectric response current of the device is higher than that of the sample with a PTAA thickness of 100 nm. This suggests that a thinner PTAA layer (80 nm) has a weaker filtering ability for short-wavelength ultraviolet light, which reduces the blue-violet light-to-ultraviolet light suppression ratio of the device. Furthermore, the spectral response characteristics of the device are as follows: Figure 10 As shown, the test results indicate that its spectral response full width at half maximum (FWHM) is 45 nm.

[0060] The PEA2PbBr prepared in this embodiment 3.5 I 0.5 The time response curves of the thin film / PTAA (40nm) heterojunction photosynapse under monochromatic light illumination of different wavelengths are shown below. Figure 11 As shown in the figure. The results show that compared with PTAA (120nm) and PTAA (100nm) devices, the photoelectric response current of this device is significantly increased in the short-wavelength ultraviolet band. This indicates that the 40nm thick PTAA layer has extremely weak filtering ability for short-wavelength ultraviolet light, allowing a large amount of short-wavelength ultraviolet light to pass through and participate in the photoelectric response, severely reducing the blue-violet light-ultraviolet light suppression ratio and destroying the narrowband selectivity of the device. Its spectral response characteristics are as follows. Figure 12 As shown in the figure, the test results show that the full width at half maximum (FWHM) of the spectral response of the device is 51 nm, and the overall performance cannot meet the application requirements of blue-violet narrowband photoelectric synapses.

[0061] The comparative results of this embodiment show that when the PTAA thickness is in the range of 100nm~120nm, it can achieve efficient short-wave ultraviolet light blocking and excellent blue-violet light narrowband response performance.

[0062] Example 2 This embodiment compares the impact of halogen atomic composition of perovskite thin films on device performance. The device structure and fabrication method are the same as in Example 1, except that in step 3, PEA2PbBr is prepared on the PTAA hole conduction layer by spin-coating different precursor solutions. 3.5 I 0.5 ,PEA2PbBr3I,PEA2PbBr 2.5 I 1.5 PEA2PbBr4, PEA2PbCl 0.25 Br 3.75 and PEA2PbCl 0.5 Br 3.5 The raw material amounts for the corresponding precursor solutions of perovskite thin films are shown in Table 1: Table 1 Composition of perovskite precursor solution

[0063] Add the corresponding raw materials from Table 1 to a 0.5 mL mixture of N,N-dimethylformamide (DMF) / dimethyl sulfoxide (DMSO) (DMF to DMSO volume ratio 3:2) to prepare PEA2PbBr4 and PEA2PbBr. 3.5 I 0.5 ,PEA2PbBr3I,PEA2PbBr 2.5 I 1.5 ,PEA2PbCl 0.25 Br 3.75 and PEA2PbCl 0.5 Br 3.5 Perovskite precursor solution.

[0064] Absorption spectra of perovskite thin films with different halogen ratios, such as Figure 4 As shown in the figure, the perovskite films prepared in this embodiment all exhibit good selective absorption characteristics in the blue-violet light band in the range of 380nm~490nm, which can meet the material requirements for narrow-band response of blue-violet light.

[0065] In this embodiment, PEA2PbBr3I and PEA2PbBr were prepared. 2.5 I 1.5 PEA2PbBr4, PEA2PbCl 0.25 Br 3.75 and PEA2PbCl 0.5 Br 3.5 The time response curves and spectral response characteristics of the heterojunction photosynapses composed of thin films and PTAA (120 nm) under monochromatic light illumination of different wavelengths are shown in the figure below. Figures 13-22 As shown. Tests show that all devices exhibit stable and repeatable photoelectric responses and good short-wavelength ultraviolet light suppression capabilities, achieving excellent narrowband responses in the blue-violet light band: the PEA2PbBr3I device has a full width at half maximum (FWHM) of 46 nm, and the PEA2PbBr... 2.5 I 1.5 The full width at half maximum (FWHM) of the device is 49 nm, while that of the PEA2PbBr4 device is 23 nm. 0.25 Br 3.75 The device has a full width at half maximum (FWHM) of 20 nm, PEA2PbCl 0.5 Br 3.5 The device has a full width at half maximum (FWHM) of 18 nm. Overall, this invention allows for flexible adjustment of the narrowband response width within the range of 18–49 nm by controlling the halogen composition.

[0066] Wavelength-dependent time-response and spectral response tests were conducted on perovskite / PTAA (120 nm) heterojunction photosynapses with different halogen compositions. The results showed that halogen composition modulation significantly affected the spectral response range, blue light response intensity, and narrowband characteristics of the devices. Overall, the addition of I element shifted the long-wavelength cutoff response band towards the long-wavelength blue light band, while the addition of Cl element shifted the long-wavelength cutoff response band towards the short-wavelength violet light band. With increasing I addition ratio, the long-wavelength photocurrent increased after 450 nm, the spectral selectivity decreased, and the narrowband characteristics gradually weakened, with the FWHM increasing from 44 nm to 49 nm. However, devices with PEA2PbBr4 and Cl addition (PEA2PbCl...) showed... 0.25 Br 3.75 ,PEA2PbCl 0.5 Br 3.5 Although it has a stable and repeatable spectral current response, its response in the 405nm~450nm blue light band is weak, and its blue light absorption and photoelectric conversion capabilities are limited. Moreover, as the proportion of Cl added increases, the FWHM gradually decreases. Although the narrow band performance of the spectrum is improved, the peak response shifts to the violet light band, the blue light response is further attenuated, and the spectral selectivity is biased towards the violet light region, which limits its application in narrow band blue light sensing.

[0067] Example 3 This embodiment focuses on the PEA2PbBr prepared in Example 1. 3.5 I 0.5 The blue-violet narrowband photosynaptic function of the thin film / PTAA (120nm) heterojunction blue-violet narrowband photosynapse was studied in more depth.

[0068] PEA2PbBr 3.5 I 0.5 The time response curves of the thin film / PTAA (120nm) heterojunction blue-violet narrowband photosynapse under single-pulse and double-pulse blue light excitation are as follows: Figure 23 As shown in the curve, the device exhibits a rapid response and slow decay current change characteristic under light pulse stimulation. Furthermore, the amplitude and decay characteristics of the response current under dual-pulse excitation are highly consistent with the pulse timing-dependent plasticity of biological synapses, demonstrating significant and stable biological synaptic response behavior.

[0069] PEA2PbBr 3.5 I 0.5 The LTP response curves of the thin film / PTAA (120nm) heterojunction blue-violet narrowband photosynapse under different light intensities, pulse durations, and pulse counts are shown below. Figure 24 , 25 As shown in Figure 26, it can be seen from the figure that the device exhibits good LTP response as the light intensity increases, the duration of the light pulse increases, and the number of light pulses increases.

[0070] Figure 24 The display shows that as the intensity of blue-violet light decreases from 0.018 mW / cm², the effect of light intensity decreases. 2 Increased to 33.4 mW / cm 2 The device response current amplitude increased significantly and the decay rate slowed down, indicating that enhanced light intensity can effectively induce the LTP effect. Figure 25 This indicates that when the pulse duration ∆t is extended from 0.1s to 1s, the peak response current and steady-state current of the device increase simultaneously, and the non-volatility of the synaptic weights is enhanced. Figure 26 It can be seen that under repetitive pulse stimulation at a frequency (f) = 2Hz, as the number of pulses N increases from 5 to 40, the device current shows a cumulative increase and eventually reaches a stable LTP state, which fully verifies that the device has good synaptic plasticity and memory characteristics.

[0071] Figure 27 As a weighted current for fingerprint recognition, during the simulation of fingerprint ridge feature extraction, the blue fluorescent signal emitted by the fingerprint ridge was simulated by 430nm LED light, and the deep ultraviolet light signal reflected by the fingerprint valley was simulated by 265nm LED light, and the results were compared and analyzed. The results show that the narrowband photoelectric synaptic device can effectively suppress the interference response caused by the reflected deep ultraviolet light. This characteristic enables the narrowband blue-violet light synaptic device to effectively distinguish between fingerprint ridges and valleys, and significantly enhance the clarity of blurred fingerprint images. Figure 28 This visually demonstrates the dynamic change in fingerprint recognition accuracy during model training after narrowband photoelectric synapse preprocessing. Figure 29 The corresponding model training loss function variation curve is also presented. Model training test results show that, after multiple training iterations and optimizations, the fingerprint recognition model relying on narrowband photoelectric synapse preprocessing achieves a final recognition accuracy of 97.8%, highlighting the significant advantages and practical value of this narrowband blue-violet photoelectric synapse in fingerprint preprocessing and high-precision recognition applications.

[0072] As can be seen from the above, this invention achieves synergistic optimization of the optical response characteristics and synaptic performance of blue-violet narrowband photoelectric synaptic devices by precisely optimizing two core process parameters: the thickness of the PTAA hole conduction layer and the halogen (Cl / Br / I) composition ratio of the perovskite active layer. Ultimately, the device exhibits excellent characteristics of "nearly complete suppression of ultraviolet response and optimal response performance in the blue-violet region", significantly improving the spectral response selectivity and photoelectric synaptic function stability of the device.

[0073] 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 within the protection scope of the present invention.

Claims

1. A method for performance modulation of a perovskite heterojunction blue-violet narrowband photosynapse, characterized in that: Using a heterojunction composed of a poly[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] hole-conducting layer and a perovskite thin film as the functional unit, the light response in the short-wavelength ultraviolet band with a wavelength <375nm is suppressed by optimizing the thickness of the hole-conducting layer. At the same time, the light absorption range of the film is optimized by controlling the type and ratio of halogen atoms in the perovskite thin film, so that the device generates a narrow-band synaptic response only in the blue-violet light band with a wavelength range of 380nm~490nm, thereby realizing the blue-violet light narrow-band photoelectric synaptic function.

2. The method for performance modulation of the perovskite heterojunction blue-violet narrowband photosynapse according to claim 1, characterized in that: The perovskite film is configured as a PEA2PbBr film with a Br / I atomic ratio of x:y. x I y A thin film, wherein x is 2.5~4, y is 0~1.5, and x+y=4; or the perovskite thin film is configured as PEA2PbCl with a Cl / Br atomic ratio of s:t. s Br t The thin film has a value of s (0~0.5) and a value of t (3.5~4), and s+t=4.

3. The method for performance modulation of the perovskite heterojunction blue-violet narrowband photosynapse according to claim 1 or 2, characterized in that: The thickness of the hole conduction layer is set to 100nm~200nm.

4. A perovskite heterojunction blue-violet narrowband photosynapse, characterized in that: The performance is obtained by using the performance control method described in any one of claims 1 to 3.

5. The perovskite heterojunction blue-violet narrowband photosynapse according to claim 4, characterized in that, The device structure is as follows: a transparent insulating substrate is used as the substrate; a poly[bis((4-phenyl))(2,4,6-trimethylphenyl)amine] hole conducting layer is disposed on the upper surface of the substrate; a perovskite thin film is disposed on the hole conducting layer; the perovskite thin film and the hole conducting layer form a heterojunction; and a metal electrode is disposed on the perovskite thin film.

6. The perovskite heterojunction blue-violet narrowband photosynapse according to claim 5, characterized in that: The thickness of the perovskite thin film is 200 nm to 400 nm.

7. The perovskite heterojunction blue-violet narrowband photosynapse according to claim 5, characterized in that: The metal electrode is a Ni electrode with a thickness of 80nm~100nm.

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