An optoelectronic synapse device covering UV, RGB bands and a preparation method and application thereof

Abstract

The application belongs to the technical field of photoelectric synapse, bionic vision and wide-spectrum photoelectric device, and discloses a photoelectric synapse device covering UV and RGB bands and a preparation method and application thereof. The photoelectric synapse device comprises, from bottom to top, a substrate, a bottom electrode, a light absorption layer and a top electrode; wherein the light absorption layer is a three-layer composite heterojunction structure comprising, from bottom to top, a TiO2 nanorod film layer, an amorphous oxide insertion layer and a SnS x film, and the TiO2 nanorod film layer is grown on the bottom electrode. The photoelectric synapse device can cover UV+RGB wide bands and has good synaptic plasticity.

Description

Technical Field

[0001] This invention relates to the fields of photoelectric synapses, bionic vision, and broadband optoelectronic devices, and in particular to a photoelectric synapse device covering the UV and RGB bands, its fabrication method, and its applications. Background Technology

[0002] The human visual system responds only to the visible light band (380-780nm), while some birds and insects (such as bees and butterflies) possess a four-color visual system (UV+RGB), enabling them to perceive ultraviolet light information and thus have a stronger ability to adapt to complex lighting environments. To simulate this advanced visual function, the development of artificial visual perception synaptic devices capable of responding to a wide spectral range from ultraviolet to visible light has become a current research hotspot. Currently, optoelectronic synaptic devices based on semiconductor materials have been extensively studied. However, single materials are often limited by their inherent optical band gaps, making it difficult to cover a wide spectral range from ultraviolet to visible. For example, wide-bandgap semiconductors (such as TiO2 and Ga2O3) are sensitive to ultraviolet light but weak to visible light; while narrow-bandgap materials (such as SnS2 and MoS2) primarily respond to visible light. While existing technologies can achieve spectral complementarity by constructing heterojunctions, traditional PN junction or heterojunction devices often pursue rapid photogenerated carrier separation and recombination (i.e., fast response), resulting in short photocurrent relaxation times that cannot simulate the long-term plasticity of biological synapses. Simple bilayer heterojunctions, due to their narrow defect level distribution, struggle to achieve efficient responses across multiple independent wavelengths, including ultraviolet, blue, green, and red (UV+RGB). Furthermore, the limited capacity of potential barriers or wells at the bilayer heterojunction interface to accumulate charge carriers hinders the formation of sustained photoconductivity, thus restricting their application in neuromorphic computing.

[0003] Therefore, there is an urgent need to develop an optoelectronic synaptic device that can cover a wide UV+RGB band and has good synaptic plasticity. Summary of the Invention

[0004] The purpose of this invention is to address the technical problems of existing photoelectric synaptic devices, such as narrow response bands, difficulty in simultaneously covering the entire ultraviolet to visible light spectrum, and excessively rapid photocurrent relaxation, which fails to simulate long-term synaptic plasticity. This invention provides a photoelectric synaptic device covering the UV and RGB bands, its fabrication method, and its applications. The photoelectric synaptic device can simulate the function of a biological multicolor visual system.

[0005] The technical solution adopted to achieve the purpose of this invention is: A photoelectric synapse device covering the UV and RGB wavelength bands, comprising, from bottom to top, a substrate, a bottom electrode, a light-absorbing layer, and a top electrode; wherein: The light-absorbing layer is a three-layer composite heterojunction structure, consisting of a TiO2 nanorod thin film layer, an amorphous oxide insertion layer, and a SnS layer from bottom to top. x The thin film, wherein the TiO2 nanorod thin film layer is grown on the bottom electrode.

[0006] Preferably, the amorphous oxide insertion layer is any combination of one, two, or three of ITZO, IGZO, or IAZO. The TiO2 nanorod thin film layer is a rutile phase TiO2 nanorod array; The SnS x The thin film is a nanosheet structure composed of a mixed phase of SnS and SnS2. x The thin film is uniformly covered on the amorphous oxide insertion layer, and forms a tight electrical contact with the underlying TiO2 through the amorphous oxide insertion layer.

[0007] The sandwich structure of the light-absorbing layer fully utilizes the characteristics of each layer: TiO2 mainly contributes to the ultraviolet light response, the amorphous oxide layer rich in oxygen vacancy defects broadens the visible light response and serves as a carrier modulation center, while SnS... x The thin film absorbs green and red light waves.

[0008] Preferably, the thickness of the TiO2 nanorod film layer is 1-2.5 μm, the thickness of the amorphous oxide intercalation layer is 400-900 nm, and the thickness of the SnS... x The thickness of the thin film is 350-700 nm, and the thickness of the top electrode is 50-150 nm; The substrate is made of glass or PET, the bottom electrode is made of ITO, FTO, or an aluminum-doped zinc oxide conductive substrate, and the top electrode is made of any one of Au, Pt, Ag, Cu, Ti, and Al. The area of ​​the top electrode is 0.01-0.05 cm². 2 .

[0009] Another aspect of the present invention includes a method for fabricating the photoelectric synaptic device, comprising the following steps: Step S1: Pretreatment of substrate and bottom electrode; Step S2: Dissolve the titanium source in a mixed solvent to prepare a TiO2 precursor solution. Place the pretreated substrate and bottom electrode obtained in step S1 into the TiO2 precursor solution, and prepare a TiO2 nanorod thin film layer on the bottom electrode using a hydrothermal method. In step S3, indium salt, zinc salt and doped metal salt are dissolved in a solvent, and a stabilizer is added to prepare a precursor solution. The precursor solution is then uniformly coated onto the TiO2 nanorod film layer obtained in step S2 by spin coating. After annealing, an amorphous oxide insertion layer is obtained. The amorphous oxide not only passivates the surface defects of TiO2, but also fills part of the gaps between the TiO2 nanorods. Step S4: Dissolve the tin source and sulfur source in ethanol to prepare SnS. x The composite substrate obtained in step S3 is immersed in the reaction solution, followed by chemical bath deposition, cleaning, and vacuum drying to obtain SnS. x Thin film layer; Step S5, in the SnS x The top electrode is deposited or sputtered on the thin film, preferably with a sputtering power of 50-150W.

[0010] Preferably, in step S1, the substrate with the bottom electrode is ultrasonically cleaned with acetone, isopropanol, anhydrous ethanol and deionized water for 15-25 minutes, then dried with nitrogen and in an oven for 10-30 minutes.

[0011] Preferably, in step S2, the titanium source is tetrabutyl titanate, the mixed solvent is a mixed solution of deionized water, ethanol and hydrochloric acid, with a volume ratio of (1-5):1:(0.01-0.06), the concentration of the titanium source in the mixed solvent is 0.01-0.1 mol / L, the hydrothermal reaction temperature is 180-200℃, the hydrothermal reaction time is 1.5-3 h, the drying temperature is 80-150℃, and the drying time is 1-5 h.

[0012] Preferably, in step S3, the indium salt is In(NO3)3·xH2O, where x = 7, 8, or 9, and the zinc salt is Zn(NO3)2·6H2O; when the amorphous oxide insertion layer is ITZO, the doped metal salt is SnCl2·2H2O; when the amorphous oxide insertion layer is IGZO, the doped metal salt is Ga(NO3)3·xH2O, where x = 8 or 9; and when the amorphous oxide insertion layer is IAZO, the doped metal salt is Al(NO3)3·xH2O. ·9H2O; the solvent is 2-methoxyethanol or propylene glycol methyl ether, the stabilizer is monoethanolamine or triethylamine, the volume ratio of stabilizer to solvent is (1-3):100, the total concentration of metal ions in the precursor solution is 0.3-0.8 mol / L, the molar ratio of In in indium salt, metal in doped metal salt and zinc in zinc salt is 9:(1-2):3, the metal in doped metal salt is Sn, Ga or Al, and the above precursor solution is aged for 12-48 h before spin coating.

[0013] Preferably, in step S3, the spin coating process is as follows: a precursor solution is dropped onto the TiO2 nanorod film layer and spin-coated at a speed of 3500-6000 r / min for 30-50 s, followed by holding at 300-400℃ for 10-20 min to remove organic matter; the spin coating is completed after repeating the operation 8-15 times; the repeated operation is to spin-coat the same precursor solution on different layers, or to alternately spin-coat any combination of two or three precursor solutions; the annealing is carried out in an air atmosphere, the annealing temperature is 400-450℃, and the annealing time is 1-1.5 h.

[0014] Preferably, in step S4, the tin source is SnCl2·2H2O, the sulfur source is thioacetamide, the solvent is anhydrous ethanol, the mixture is stirred at 300-600 r / min for 15-30 min to obtain a black solution, the substrate is immersed face down, the mixture is stirred at 350-500 r / min, the reaction temperature is 70-90℃, the reaction time is 1-2 h, the vacuum drying temperature is 60℃, and the drying time is 2-6 h.

[0015] Another aspect of the present invention includes the application of the photoelectric synaptic device covering the UV and RGB bands in a simulated biological multicolor vision system.

[0016] Compared with the prior art, the beneficial effects of the present invention are: 1. The photoelectric synapse device of the present invention adopts TiO2 nanorods + amorphous oxide intercalation layer + SnS X A three-layer heterojunction structure overcomes the bandgap limitations of single materials, achieving high-efficiency response across the UV+RGB bands. The three-layer heterojunction interface forms abundant defect energy levels and carrier modulation centers. The amorphous oxide insertion layer passivates TiO2 surface defects and fills the gaps between nanorods, improving device stability and carrier transport efficiency. SnS X By forming a tight electrical contact with amorphous oxides, multi-band light absorption and photoelectric conversion are enhanced, and the photocurrent relaxation time is extended. This can simulate the long-term plasticity of biological synapses and solve the problem that traditional heterojunction photocurrent relaxation is too fast and cannot be adapted to neuromorphic computing.

[0017] 2. The photoelectric synapse device of the present invention is prepared using low-temperature processes such as hydrothermal method, spin coating, and chemical bath deposition, and is compatible with glass and PET flexible substrates, with a wide range of applications.

[0018] 3. The photoelectric synaptic device of the present invention can directly simulate the biological multicolor visual system and has practical application prospects in the fields of bionic vision, broadband photoelectric sensing, and neuromorphic computing. Attached Figure Description

[0019] Figure 1 The SnS-based embodiment provided by the present invention xA schematic diagram of a photoelectric synaptic device based on an amorphous oxide intercalation layer / TiO2 heterojunction. Wherein, 1-substrate; 2-bottom electrode; 3-TiO2 nanorod thin film layer; 4-amorphous oxide intercalation layer; 5-SnS… x Thin film; 6-top electrode.

[0020] Figure 2 This is based on SnS provided in Embodiment 1 of the present invention. x Scanning electron microscope image of an ITZO / TiO2 heterojunction photoelectric synaptic device.

[0021] Figure 3 The following is a graph showing the test results of the plasticity behavior of the photoelectric synaptic device provided in Embodiment 1 of the present invention, depending on the intensity of different wavelength light pulses: Figure 3 a wavelength of 365nm, Figure 3 b wavelength 457nm, Figure 3 c wavelength 525nm, Figure 3 d wavelength 730nm.

[0022] Figure 4 The following is a graph showing the test results of the plasticity behavior of the photoelectric synaptic device provided in Embodiment 2 of the present invention, depending on the intensity of different wavelength light pulses: Figure 4 a wavelength of 365nm, Figure 4 b wavelength 457nm, Figure 4 c wavelength 525nm, Figure 4 d wavelength 730nm.

[0023] Figure 5 The following is a graph showing the test results of the plasticity behavior of the photoelectric synaptic device provided in Embodiment 3 of the present invention, which is dependent on the intensity of different wavelength light pulses: Figure 5 a wavelength of 365nm, Figure 5 b wavelength 457nm, Figure 5 c wavelength 525nm, Figure 5 d wavelength 730nm. Detailed Implementation

[0024] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Example 1

[0025] like Figure 1 As shown, a photoelectric synapse device covering the UV and RGB bands includes, from bottom to top, a substrate 1, a bottom electrode 2, a light absorption layer and a top electrode 6. Wherein: the light-absorbing layer is a three-layer composite heterojunction structure, which, from bottom to top, includes a TiO2 nanorod thin film layer 3, an amorphous oxide insertion layer 4, and a SnS layer. xThin film 5, wherein the TiO2 nanorod thin film layer 3 is a rutile phase TiO2 nanorod array grown on the bottom electrode 2.

[0026] The method for fabricating the photoelectric synaptic device includes the following steps: Step S1, Substrate pretreatment: The FTO conductive glass is ultrasonically treated with acetone, isopropanol, anhydrous ethanol and deionized water for 20 min each, dried with nitrogen and then dried at 80°C for 20 min.

[0027] Step S2, TiO2 nanorod film: Deionized water, hydrochloric acid and ethanol are mixed in a volume ratio of 3:1:0.05, tetrabutyl titanate is added to a concentration of 0.05mol / L, and the mixture is stirred for 30min; FTO is placed in the reaction vessel with the conductive side facing down, and hydrothermally heated at 180℃ for 2.5h. After cooling, the mixture is rinsed and dried at 80℃ for 2h to obtain TiO2 nanorod film.

[0028] Step S3, ITZO preparation: In(NO3)3·9H2O, SnCl2·2H2O, and Zn(NO3)2·6H2O were dissolved in 2-methoxyethanol at a molar ratio of 9:1:3. 2% (v / v) monoethanolamine was added to prepare a solution with a total metal concentration of 0.5 mol / L. The solution was stirred for 12 h and aged for 24 h. Using the TiO2 nanorod film obtained in Step 2 as a substrate, the above solution was spin-coated at 4000 r / min for 30 s, baked at 350℃ for 15 min, and repeated 10 times. Finally, it was annealed in air at 400℃ for 1 h to obtain an ITZO / TiO2 nanorod composite film.

[0029] Step S4, SnS Preparation: 100 mL of ethanol was heated to 80 °C, 0.01 mol SnCl2·2H2O was added to dissolve it, and then 0.03 mol thioacetamide was added. The mixture was stirred at 500 rpm for 20 min to obtain a black solution. The substrate was immersed face down and stirred at 400 rpm for 1 h at 80 °C. After rinsing, the mixture was vacuum dried at 60 °C for 4 h.

[0030] Step S5, Top electrode fabrication: Magnetron sputtering of an Au electrode, power 100W, thickness 80nm, electrode area 0.02cm². 2 Au / SnS x / ITZO / TiO2 / FTO devices.

[0031] Figure 2 This is a scanning electron microscope characterization image of the photoelectric synaptic device obtained according to an embodiment of the present invention.

[0032] Figure 3The figures show the It curves of the photoelectric synaptic device obtained according to an embodiment of the present invention under different wavelength pulsed light illumination. A positive bias voltage of 0.2V was applied to the bottom electrode of the device, the light pulse consisted of 1s on + 1s off, and the light irradiance was 10mW / cm². 2 10 pulses were measured continuously. Example 2

[0033] The differences between this embodiment and Embodiment 1 are as follows: Step S1: Use PET coated with an ITO conductive film as a substrate; Step S3, the preparation of the ITZO solution is the same as in Example 1. The IGZO solution is prepared separately as follows: In(NO3)3·9H2O, Ga(NO3)3·8H2O, and Zn(NO3)2·6H2O are dissolved in 2-methoxyethanol at a molar ratio of 9:1.5:3. 3% (v / v) monoethanolamine is added to prepare a solution with a total metal concentration of 0.6 mol / L. The solution is stirred for 12 h and aged for 24 h. Using the TiO2 nanorod film obtained in Step 2 as a substrate, the above ITZO solution is spin-coated at 4000 r / min for 30 s, baked at 350 °C for 15 min, and repeated 6 times. The above IGZO solution is spin-coated at 5000 r / min for 40 s, baked at 400 °C for 20 min, and repeated 6 times. Annealing is then performed at 400 °C in air for 1.5 h to obtain an IGZO:ITZO / TiO2 nanorod composite film.

[0034] Step S5, Top electrode fabrication: Pt electrode fabricated by magnetron sputtering, power 110W, thickness 90nm, electrode area 0.04cm². 2 To obtain Pt / SnS x / ITZO / TiO2 / ITO devices.

[0035] Figure 4 The figures show the It curves of the photoelectric synaptic device obtained according to an embodiment of the present invention under different wavelength pulsed light illumination. A positive bias voltage of 0.2V was applied to the bottom electrode of the device, the pulse consisted of 1s on + 1s off, and the light irradiance was 10mW / cm². 2 10 pulses were measured continuously. Example 3

[0036] Based on SnS Fabrication of photoelectric synaptic devices of / ITZO:IAZO:IGZO / TiO2.

[0037] The differences between this embodiment and Embodiment 2 are as follows: Step S1: Use glass coated with an ITO conductive film as a substrate; Step S3, the preparation of ITZO solution and IGZO solution is the same as in Example 2. Additionally, IAZO solution is prepared as follows: In(NO3)3·9H2O, Al(NO3)3·9H2O, and Zn(NO3)2·6H2O are dissolved in 2-methoxyethanol at a molar ratio of 9:2:3. 2% (v / v) monoethanolamine is added to prepare a solution with a total metal concentration of 0.7 mol / L. The solution is stirred for 12 h and aged for 24 h. Using the TiO2 nanorod film obtained in step 2 as a substrate, the above IGZO solution was spin-coated at 5000 r / min for 40 s, baked at 400℃ for 20 min, and the cycle was repeated 3 times; the above IAZO solution was spin-coated at 6000 r / min for 30 s, baked at 400℃ for 20 min, and the cycle was repeated 3 times; the above ITZO solution was spin-coated at 4000 r / min for 30 s, baked at 350℃ for 1 min, and the cycle was repeated 3 times; and annealed in air at 400℃ for 1.5 h to obtain an ITZO:IAZO:IGZO / TiO2 nanorod composite film.

[0038] Step S5, Top electrode fabrication: Magnetron sputtering of a Ti electrode, power 100W, thickness 80nm, electrode area 0.03cm². 2 Ti / SnS / ITZO:IAZO:IGZO / TiO2 / ITO device.

[0039] Figure 5 The figures show the It curves of the photoelectric synaptic device obtained according to an embodiment of the present invention under different wavelength pulsed light illumination. A positive bias voltage of 0.2V was applied to the bottom electrode of the device, the light pulse consisted of 1s on and 1s off, and the light irradiance was 6mW / cm². 2 10 pulses were measured continuously.

[0040] Depend on Figure 3 , Figure 4 and Figure 5 It can be seen that when a positive bias voltage of 0.2V is applied to the electrodes of the three synaptic devices, 10 light pulses with wavelengths of 365nm, 475nm, 525nm and 730nm are applied continuously with a light on for 1s and a light off for 1s, respectively. As the number of pulses increases, the photocurrent continuously increases. Figure 3 a, Figure 3 b, Figure 3 c and Figure 3 The photocurrent in the middle d phase is 1.22 × 10⁻⁶ from the first pulse. -7 0.65×10 -7 0.68×10 -7 Anhe 2.68×10 -8 An, increased to 2.13 × 10⁻⁶ pulses for the tenth pulse. -7 1.21×10 -7 1.17×10-7 Anhe 3.61×10 -8 install. Figure 4 a, Figure 4 b, Figure 4 c and Figure 4 The photocurrent in the middle d phase is 1.13 × 10⁻⁶ from the first pulse. -7 1.28×10 -7 1.28×10 -7 Anhe 1.06×10 -8 An, increased to 2.84 × 10 on the tenth pulse. -7 2.15×10 -7 1.83×10 -7 Anhe 1.09×10 -8 install. Figure 5 a, Figure 5 b, Figure 5 c and Figure 5 The photocurrent in the middle d phase was 0.93 × 10⁻⁶ from the first pulse. -7 1.22×10 -7 1.20×10 -7 Anhe 1.06×10 -8 An, increased to 2.31 × 10⁻⁶ pulses for the tenth pulse. -7 1.79×10 -7 1.52×10 -7 Anhe 1.08×10 -8 install.

[0041] It can be seen that the photoelectric synaptic devices obtained in the three embodiments all showed a continuous increase in photocurrent under ultraviolet (365nm), blue (475nm), green (525nm), and red (730nm) light stimulation. Moreover, after the light pulse ended, the current did not recover to the initial value before the pulsed light was applied even after tens of seconds. The synaptic devices showed excitatory postsynaptic current and good synaptic plasticity behavior in the UV and RGB bands, laying the foundation for the application of the devices in the fields of simulating biological multicolor vision systems, broadband photoelectric sensing, and neuromorphic computing.

[0042] The device can be fabricated by adjusting the fabrication process according to the invention described in this specification, and the device basically shows the same properties as the embodiments after testing.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A photoelectric synaptic device covering the UV and RGB bands, characterized in that, From bottom to top, it includes a substrate, a bottom electrode, a light-absorbing layer, and a top electrode; wherein: The light-absorbing layer is a three-layer composite heterojunction structure, consisting of a TiO2 nanorod thin film layer, an amorphous oxide insertion layer, and a SnS layer from bottom to top. x The thin film, wherein the TiO2 nanorod thin film layer is grown on the bottom electrode.

2. The photoelectric synapse device as described in claim 1, characterized in that, The amorphous oxide insertion layer is any combination of one, two, or three of ITZO, IGZO, or IAZO. The TiO2 nanorod thin film layer is a rutile phase TiO2 nanorod array; The SnS x The thin film is a nanosheet structure composed of a mixed phase of SnS and SnS2.

3. The photoelectric synapse device as described in claim 1, characterized in that, The thickness of the TiO2 nanorod thin film is 1-2.5 μm, the thickness of the amorphous oxide insertion layer is 400-900 nm, and the thickness of the SnS... x The thickness of the thin film is 350-700 nm, and the thickness of the top electrode is 50-150 nm; The substrate is made of glass or PET, the bottom electrode is made of ITO, FTO, or an aluminum-doped zinc oxide conductive substrate, and the top electrode is made of any one of Au, Pt, Ag, Cu, Ti, and Al. The area of ​​the top electrode is 0.01-0.05 cm². 2 .

4. The method for fabricating the photoelectric synaptic device according to any one of claims 1-3, characterized in that, Includes the following steps: Step S1: Pretreatment of substrate and bottom electrode; Step S2: Dissolve the titanium source in a mixed solvent to prepare a TiO2 precursor solution. Place the pretreated substrate and bottom electrode obtained in step S1 in the TiO2 precursor solution and prepare a TiO2 nanorod thin film layer on the bottom electrode using a hydrothermal method. In step S3, indium salt, zinc salt and doped metal salt are dissolved in a solvent, and then a stabilizer is added to prepare a precursor solution. The precursor solution is uniformly coated onto the TiO2 nanorod film layer obtained in step S2 by spin coating. After annealing, an amorphous oxide insertion layer film layer is obtained. Step S4: Dissolve the tin source and sulfur source in ethanol to prepare SnS. x The composite substrate obtained in step S3 is immersed in the reaction solution, followed by chemical bath deposition, cleaning, and vacuum drying to obtain SnS. x Thin film layer; Step S5, in the SnS x Top electrode is deposited or sputtered onto a thin film.

5. The preparation method according to claim 4, characterized in that, In step S1, the substrate with the bottom electrode is ultrasonically cleaned with acetone, isopropanol, anhydrous ethanol and deionized water for 15-25 minutes, then dried with nitrogen and in an oven for 10-30 minutes.

6. The preparation method according to claim 4, characterized in that, In step S2, the titanium source is tetrabutyl titanate, the mixed solvent is a mixed solution of deionized water, ethanol and hydrochloric acid, with a volume ratio of (1-5):1:(0.01-0.06), the concentration of the titanium source in the mixed solvent is 0.01-0.1 mol / L, the hydrothermal reaction temperature is 180-200℃, the hydrothermal reaction time is 1.5-3 h, the drying temperature is 80-150℃, and the drying time is 1-5 h.

7. The preparation method according to claim 4, characterized in that, In step S3, the indium salt is In(NO3)3·xH2O, where x = 7, 8, or 9, and the zinc salt is Zn(NO3)2·6H2O. When the amorphous oxide insertion layer is ITZO, the doped metal salt is SnCl2·2H2O; when the amorphous oxide insertion layer is IGZO, the doped metal salt is Ga(NO3)3·xH2O, where x = 8 or 9; and when the amorphous oxide insertion layer is IAZO, the doped metal salt is Al(NO3)3·9H2O. 2O; the solvent is 2-methoxyethanol or propylene glycol methyl ether, the stabilizer is monoethanolamine or triethylamine, the volume ratio of stabilizer to solvent is (1-3):100, the total concentration of metal ions in the precursor solution is 0.3-0.8 mol / L, the molar ratio of In in indium salt, metal in doped metal salt and zinc in zinc salt is 9:(1-2):3, the metal in doped metal salt is Sn, Ga or Al, and the above precursor solution is aged for 12-48 h before spin coating.

8. The preparation method according to claim 4, characterized in that, In step S3, the specific steps of spin coating are as follows: a precursor solution is dropped onto the TiO2 nanorod film layer and spin-coated at a speed of 3500-6000 r / min for 30-50 s, followed by holding at 300-400℃ for 10-20 min to remove organic matter; the spin coating is completed after repeating the operation 8-15 times; the repeated operation is to spin-coat the same precursor solution on different layers, or to spin-coat any combination of two or three precursor solutions alternately; the annealing is carried out in an air atmosphere, the annealing temperature is 400-450℃, and the annealing time is 1-1.5 h.

9. The preparation method according to claim 4, characterized in that, In step S4, the tin source is SnCl2·2H2O, the sulfur source is thioacetamide, and the solvent is anhydrous ethanol. The mixture is stirred at 300-600 r / min for 15-30 min to obtain a black solution. The substrate is then immersed face down in the solution and stirred at 350-500 r / min. The reaction temperature is 70-90℃, and the reaction time is 1-2 h. The vacuum drying temperature is 60℃, and the drying time is 2-6 h.

10. The application of the photoelectric synaptic device covering the UV and RGB bands as described in any one of claims 1-3 in a simulated biological multicolor vision system.

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