Ultraviolet photoelectric detector and preparation method thereof

Abstract

The invention discloses an ultraviolet photoelectric detector and a preparation method thereof, and belongs to the field of ultraviolet detection. The problems that an existing organic-inorganic biological hybrid photoelectric detector is low in performance due to the fact that the matching degree of the energy band structure, the electrical property and the optical property of a low-dimensional nano material and an organic biological material cannot be improved, and a modification method of the organic biological material is complex and high in cost are solved. The ultraviolet photoelectric detector is composed of a metal Au electrode, a metal In electrode, a bacterial pigment layer, a ZnO nanorod array layer and FTO conductive glass. The method comprises the following steps: 1, preparing a ZnO nanorod array layer on the surface of FTO conductive glass, then spin-coating bacterial pigment, and finally annealing; and 2, preparing a metal Au electrode and a metal In electrode. The invention is used for the ultraviolet photoelectric detector and the preparation thereof.

Description

Technical Field

[0001] The invention belongs to the field of ultraviolet light detection. Background Art

[0002] Ultraviolet photodetectors (PDs) are electronic information devices that convert incident light (λ<400nm) into electrical signals based on the photoelectric effect. Ultraviolet photodetectors have a wide range of applications in marine engineering such as ocean water quality detection, biological monitoring, ocean exploration and communication, environmental monitoring, and security search due to their high efficiency and sensitive optical signal detection capabilities within a specific ultraviolet wavelength range. Wide-bandgap semiconductor materials (TiO2, GaN, SnO2, ZnO, etc.) are ideal active layers for ultraviolet photodetectors due to their quasi-continuous band structures. Semiconductor materials such as ZnO have the characteristics of wide bandgap, high electron mobility, non-toxicity, and environmental friendliness, and have been widely used in ultraviolet photodetectors in recent years. However, these materials alone are prone to non-radiative recombination of electron-hole pairs as photodetectors, resulting in a decrease in photodetection efficiency. In order to solve the problem of low detection efficiency, low-dimensional ZnO nanomaterials are usually prepared, such as 0D ZnO quantum dots and 1D ZnO nanomaterials (nanowires, nanorods, nanotubes, etc.). Low-dimensional ZnO nanomaterials have a high surface-to-volume ratio and a small conductive channel size, which can effectively improve the utilization rate of incident light, limit the recombination area of ​​photogenerated carriers and reduce the transmission time. In addition, the separation of electron-hole pairs in the device can also be improved by constructing semiconductor heterojunctions, such as pn junctions, metal-semiconductor-metal (MSM) structures and Schottky junctions. At present, organic-inorganic bio-hybrid photodetectors (Bio-HPDs) have received extensive attention in the field of flexible devices or transparent devices due to the easy availability and low cost of biomass materials. However, how to improve the material properties of low-dimensional nanomaterials and organic biomaterials, especially the matching degree of band structure, electrical properties and optical properties. Simplify the preparation and modification methods of organic biomaterials and reduce their use costs. It is an urgent problem to be solved in optimizing ultraviolet photodetectors. Summary of the invention

[0003] The present invention aims to solve the problems that the existing performance of organic-inorganic biohybrid photoelectric detectors is relatively low, the modification methods of organic biomaterials are complex and costly, and thus provide an ultraviolet photoelectric detector and a preparation method thereof.

[0004] A UV photoelectric detector, which consists of a metal Au electrode, a metal In electrode, a bacterial pigment layer, a ZnO nanorod array layer and FTO conductive glass; the metal In electrode is arranged on the periphery of the FTO conductive glass surface in a frame-shaped structure, and the inside of the metal In electrode is composed of the ZnO nanorod array layer, the bacterial pigment layer and the metal Au electrode in sequence from the FTO conductive glass surface to the top.

[0005] A method for preparing an ultraviolet photoelectric detector is carried out according to the following steps:

[0006] First, a ZnO nanorod array layer was prepared on the surface of FTO conductive glass by a hydrothermal method, and then bacterial pigment was evenly spin-coated on the surface of the ZnO nanorod array layer, and then annealed in an air atmosphere to obtain a FTO / ZnO nanorod array layer / bacterial pigment layer device;

[0007] 2. A metal Au layer is prepared on the surface of the bacteriochrome layer of the FTO / ZnO nanorod array layer / bacteriochrome layer device to form a metal Au electrode, and then a coating layer with a width of 1 mm to 2 mm is scraped off around the device, and then metal In is welded to the FTO glass surface to form a metal In electrode, thereby completing the preparation method of the ultraviolet photodetector.

[0008] The beneficial effects of the present invention are:

[0009] The present invention provides an ultraviolet photodetector and a preparation method thereof. The ultraviolet photodetector is constructed of a metal Au electrode, a metal In electrode, a bacterial pigment, a ZnO nanorod array, and FTO conductive glass to form an MSM vertical structure photodetector. The obtained ultraviolet photodetector is connected to a circuit, the metal Au electrode is connected to the negative electrode, the metal In electrode is connected to the positive electrode, and a bias voltage of -1V to -5V is applied in the entire circuit, which can be 0.80mW·cm -2 ~60mW·cm -2The detection is performed by ultraviolet light of 365nm ultraviolet band with high power. Due to the difference in work function, the bacterial pigment and the ZnO nanorod array form an ohmic contact heterojunction when in contact. The bacterial pigment, as an electron transport layer, can quickly transport electrons and improve the separation effect of electron / hole pairs. When detecting ultraviolet light, the incident ultraviolet light excites the electrons in the valence band of the ZnO nanorod array, which undergo transitions and transfer to the bacterial pigment. The phenolic and quinone groups in the bacterial pigment can undergo oxidation-reduction cycle reactions under the action of electrons. The photogenerated electrons reduce the quinone groups in the bacterial pigment to phenolic groups, avoiding recombination with holes at the interface between ZnO and the bacterial pigment. The reduced phenolic groups lose electrons under the action of an external bias voltage, are oxidized to quinone groups, and the electrons are transferred to the circuit to form a photogenerated current. After such a cycle, the bacterial pigment becomes an intermediate for rapid electron transmission at the heterojunction through its redox cycle, allowing rapid electron transfer in the device, thereby improving the photoelectric detection efficiency of the ultraviolet photodetector. Compared with other inorganic or synthetic organic heterogeneous materials, the separation, extraction and application of bacterial pigments have the characteristics of low cost, easy use, simple extraction, non-toxicity, strong resistance to environmental light and heat decomposition, and bio-friendliness. It is a bio-organic material with good application potential.

[0010] The ultraviolet photoelectric detector obtained by the present invention has a strong photoelectric detection effect. It can have a strong detection effect on weak light in the ultraviolet band. -2 ~60mW·cm -2 When the 365nm ultraviolet light is used for detection, 0.14×10 5 mA·W -1 ~4.35×10 5 mA·W -1 The photoresponsivity is 2.6×10 12 Jones~1.01×10 14 Jones's detection rate. It shows excellent UV detection effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the structure of the ultraviolet photodetector of the present invention, 1 is a metal Au electrode, 2 is a metal In electrode, 3 is a bacterial pigment layer, 4 is a ZnO nanorod array layer, and 5 is FTO conductive glass;

[0012] Figure 2are scanning electron microscope images, (a) is the surface of the ZnO nanorod array layer prepared in step 1 of Example 1, (b) is the cross-section of the ZnO nanorod array layer prepared in step 1 of Example 1, (c) is the surface of the FTO / ZnO nanorod array layer / bacterial pigment layer device prepared in step 1 of Example 1, (d) is the cross-section of the FTO / ZnO nanorod array layer / bacterial pigment layer device prepared in step 1 of Example 1;

[0013] Figure 3 At -3V bias, 60mW·cm -2 IT graphs of the ultraviolet photodetectors prepared in Examples 2 to 6 and the comparative experiment at different pyomelanocortin contents under 365nm ultraviolet light;

[0014] Figure 4 The photoresponsivity and detectivity of the ultraviolet photodetector prepared in Example 1 to ultraviolet light of different optical powers under a bias voltage of -3 V, (a) is the photogenerated current, and (b) is the photoresponsivity and detectivity. DETAILED DESCRIPTION

[0015] Specific implementation method 1, combined with Figure 1 Specific description: This embodiment is a UV photodetector, which is composed of a metal Au electrode, a metal In electrode, a bacterial pigment layer, a ZnO nanorod array layer and FTO conductive glass; the metal In electrode is arranged in a frame-shaped structure on the periphery of the FTO conductive glass surface, and the interior of the metal In electrode is composed of a ZnO nanorod array layer, a bacterial pigment layer and a metal Au electrode from the FTO conductive glass surface to the top.

[0016] This specific implementation method utilizes the geometric shape advantages of low-dimensional materials to improve the transmission efficiency of photogenerated electrons, and constructs an ohmic contact heterojunction with bacterial pigments that are low-cost, easy to prepare, environmentally friendly and non-toxic, and builds an ultraviolet photodetector based on this heterostructure.

[0017] The beneficial effects of this specific implementation are:

[0018] The present embodiment provides an ultraviolet photodetector and a preparation method thereof, wherein a metal Au electrode, a metal In electrode, a bacterial pigment, a ZnO nanorod array, and FTO conductive glass are used to construct an MSM vertical structure photodetector. The obtained ultraviolet photodetector is connected to a circuit, the metal Au electrode is connected to the negative electrode, the metal In electrode is connected to the positive electrode, and a bias voltage of -1V to -5V is applied to the entire circuit, which can be 0.80mW·cm -2 ~60mW·cm -2The detection is performed by ultraviolet light of 365nm ultraviolet band with high power. Due to the difference in work function, the bacterial pigment and the ZnO nanorod array form an ohmic contact heterojunction when in contact. The bacterial pigment, as an electron transport layer, can quickly transport electrons and improve the separation effect of electron / hole pairs. When detecting ultraviolet light, the incident ultraviolet light excites the electrons in the valence band of the ZnO nanorod array, which undergo transitions and transfer to the bacterial pigment. The phenolic and quinone groups in the bacterial pigment can undergo oxidation-reduction cycle reactions under the action of electrons. The photogenerated electrons reduce the quinone groups in the bacterial pigment to phenolic groups, avoiding recombination with holes at the interface between ZnO and the bacterial pigment. The reduced phenolic groups lose electrons under the action of an external bias voltage, are oxidized to quinone groups, and the electrons are transferred to the circuit to form a photogenerated current. After such a cycle, the bacterial pigment becomes an intermediate for rapid electron transmission at the heterojunction through its redox cycle, allowing rapid electron transfer in the device, thereby improving the photoelectric detection efficiency of the ultraviolet photodetector. Compared with other inorganic or synthetic organic heterogeneous materials, the separation, extraction and application of bacterial pigments have the characteristics of low cost, easy use, simple extraction, non-toxicity, strong resistance to environmental light and heat decomposition, and bio-friendliness. It is a bio-organic material with good application potential.

[0019] The ultraviolet photoelectric detector obtained in this specific implementation has a strong photoelectric detection effect. It can have a strong detection effect on weak light in the ultraviolet band. -2 ~60mW·cm -2 When the 365nm ultraviolet light is used for detection, 0.14×10 5 mA·W -1 ~4.35×10 5 mA·W -1 The photoresponsivity is 2.6×10 12 Jones~1.01×10 14 Jones's detection rate. It shows excellent UV detection effect.

[0020] Specific embodiment 2: This embodiment is different from specific embodiment 1 in that: the thickness of the metal Au electrode is 40nm-60nm; the thickness of the metal In electrode is 50μm-150μm, and the width is 1mm-2mm; the thickness of the bacterial pigment layer is 500nm-800nm; the thickness of the ZnO nanorod array layer is 500nm-1000nm. Others are the same as specific embodiment 1.

[0021] Specific implementation method 3: This implementation method is different from specific implementation method 1 or 2 in that the size of the ultraviolet photoelectric detector is 2 cm×2 cm×(0.20-0.22) cm. The rest is the same as specific implementation method 1 or 2.

[0022] Specific embodiment 4: This embodiment is different from specific embodiments 1 to 3 in that the bacterial pigment layer is prepared from pyomelanocortin, and the molecular weight of the pyomelanocortin is 12000Da to 120000Da. Other aspects are the same as specific embodiments 1 to 3.

[0023] Specific implementation method 5: This implementation method is a method for preparing an ultraviolet photoelectric detector, which is carried out according to the following steps:

[0024] First, a ZnO nanorod array layer was prepared on the surface of FTO conductive glass by a hydrothermal method, and then bacterial pigment was evenly spin-coated on the surface of the ZnO nanorod array layer, and then annealed in an air atmosphere to obtain a FTO / ZnO nanorod array layer / bacterial pigment layer device;

[0025] 2. A metal Au layer is prepared on the surface of the bacteriochrome layer of the FTO / ZnO nanorod array layer / bacteriochrome layer device to form a metal Au electrode, and then a coating layer with a width of 1 mm to 2 mm is scraped off around the device, and then metal In is welded to the FTO glass surface to form a metal In electrode, thereby completing the preparation method of the ultraviolet photodetector.

[0026] Specific embodiment 6: This embodiment is different from specific embodiment 5 in that: the bacterial pigment described in step 1 is pyomelanocin, and the molecular weight of pyomelanocin is 12000Da to 120000Da; the annealing described in step 1 is specifically carried out in an air atmosphere at a temperature of 50°C to 90°C for 15min to 30min. The rest is the same as specific embodiment 5.

[0027] Specific embodiment 7: This embodiment is different from either specific embodiment 5 or 6 in that: the preparation of the ZnO nanorod array layer on the surface of the FTO conductive glass by the hydrothermal method described in step 1 is specifically carried out according to the following steps:

[0028] ① Add anhydrous zinc acetate and diethanolamine to isopropanol, and then heat and dissolve to obtain a ZnO precursor solution;

[0029] The concentration of anhydrous zinc acetate in the ZnO precursor solution is 0.05 mol·L -1 ~0.15mol·L -1 The concentration of diethanolamine in the ZnO precursor solution is 0.1 mol·L -1 ~0.3mol·L -1 ;

[0030] ② The coating volume is 150μL / 4cm 2 ~300μL / 4cm 2, spin coating the ZnO precursor solution on the conductive surface of the FTO conductive glass and annealing to obtain the FTO glass covered with the ZnO seed layer;

[0031] ③ Dissolve zinc nitrate hexahydrate and hexamethylenetetramine in deionized water to obtain a ZnO growth solution;

[0032] The concentration of zinc nitrate hexahydrate in the ZnO growth solution is 0.03 mol·L -1 ~0.08mol·L -1 The concentration of hexamethylenetetramine in the ZnO growth solution is 0.03 mol·L -1 ~0.08mol·L -1 ;

[0033] ④ Immerse the FTO glass covered with the ZnO seed layer in the ZnO growth solution, use a hydrothermal reactor, react for 3h to 8h at a temperature of 100℃ to 150℃, wait for the reactor to cool to room temperature, take it out and rinse the surface with pure water, then blow off the surface residue with compressed air, and finally anneal to obtain a ZnO nanorod array layer. Others are the same as the fifth or sixth embodiment.

[0034] Specific embodiment 8: This embodiment differs from specific embodiments 5 to 7 in that: the heating and dissolving in step ① is specifically to dissolve by stirring at a temperature of 50° C. to 80° C. to form a transparent solution. The rest is the same as specific embodiments 5 to 7.

[0035] Specific embodiment 9: This embodiment is different from specific embodiments 5 to 8 in that the annealing described in steps ② and ④ is performed in an air atmosphere at a temperature of 300° C. to 350° C. for 0.5 h to 1 h. The rest is the same as specific embodiments 5 to 8.

[0036] Specific embodiment 10: This embodiment differs from specific embodiments 5 to 9 in that the length of the ZnO nanorods in the ZnO nanorod array layer prepared in step ④ is 500nm to 1000nm, and the diameter is 50nm to 120nm. Other aspects are the same as specific embodiments 5 to 9.

[0037] The following examples are used to verify the beneficial effects of the present invention:

[0038] Embodiment 1:

[0039] A UV photoelectric detector, which consists of a metal Au electrode, a metal In electrode, a bacterial pigment layer, a ZnO nanorod array layer and FTO conductive glass; the metal In electrode is arranged on the periphery of the FTO conductive glass surface in a frame-shaped structure, and the inside of the metal In electrode is composed of the ZnO nanorod array layer, the bacterial pigment layer and the metal Au electrode in sequence from the FTO conductive glass surface to the top.

[0040] The thickness of the metal Au electrode is 50nm; the thickness of the metal In electrode is 100μm and the width is 2mm; the thickness of the bacterial pigment layer is 500nm-800nm; the thickness of the ZnO nanorod array layer is 500nm-1000nm.

[0041] The size of the ultraviolet photoelectric detector is 2cm×2cm×0.2cm.

[0042] A method for preparing an ultraviolet photoelectric detector is carried out according to the following steps:

[0043] First, a ZnO nanorod array layer was prepared on the surface of FTO conductive glass by a hydrothermal method, and then 400 μL of bacterial pigment was evenly spin-coated on the surface of the ZnO nanorod array layer, and then annealed for 15 minutes in an air atmosphere at a temperature of 90°C to obtain a FTO / ZnO nanorod array layer / bacterial pigment layer device;

[0044] 2. In a vacuum environment, a metal Au layer is deposited on the surface of the bacteriochrome layer of the FTO / ZnO nanorod array layer / bacteriochrome layer device by magnetron sputtering to form a metal Au electrode, and then a coating layer with a width of 2 mm is scraped off around the device, and then the metal In is melted and reshaped by a welding gun and welded to the FTO glass surface to form a metal In electrode, thereby completing the preparation method of the ultraviolet photodetector.

[0045] The bacterial pigment described in step 1 is pyomelanocortin, and the molecular weight of pyomelanocortin is 12000Da to 120000Da;

[0046] The preparation of the ZnO nanorod array layer on the surface of the FTO conductive glass by the hydrothermal method described in step 1 is specifically carried out according to the following steps:

[0047] ① Add anhydrous zinc acetate and diethanolamine to isopropanol, and then stir at 65°C for 1 hour to dissolve into a transparent solution to obtain a ZnO precursor solution;

[0048] The concentration of anhydrous zinc acetate in the ZnO precursor solution is 0.1 mol·L -1 The concentration of diethanolamine in the ZnO precursor solution is 0.2 mol·L -1 ;

[0049] ② The coating volume is 150μL / 4cm 2 , spin-coating the ZnO precursor solution on the conductive surface of the FTO conductive glass, and annealing it for 1 h in an air atmosphere at a temperature of 320°C to obtain the FTO glass covered with a ZnO seed layer;

[0050] ③ Dissolve zinc nitrate hexahydrate and hexamethylenetetramine in deionized water to obtain a ZnO growth solution;

[0051] The concentration of zinc nitrate hexahydrate in the ZnO growth solution is 0.05 mol·L -1 The concentration of hexamethylenetetramine in the ZnO growth solution is 0.05 mol·L -1 ;

[0052] ④ Immerse the FTO glass covered with the ZnO seed layer in the ZnO growth solution, use a hydrothermal reactor, react at a temperature of 120°C for 5 hours, wait for the reactor to cool to room temperature, take it out and rinse the surface with pure water, then blow off the surface residue with compressed air, and finally anneal for 1 hour in an air atmosphere at a temperature of 320°C to obtain the ZnO nanorod array layer.

[0053] The length of the ZnO nanorods in the ZnO nanorod array layer prepared in step ④ is 500nm-1000nm, and the diameter is 50nm-120nm.

[0054] Example 2: This example is different from Example 1 in that: in step 1, 300 μL of bacterial pigment is evenly spin-coated on the surface of the ZnO nanorod array layer; in step 1, annealing treatment is performed for 15 minutes in an air atmosphere at a temperature of 80° C. The rest is the same as Example 1.

[0055] Example 3: This example is different from Example 1 in that: in step 1, 350 μL of bacterial pigment is evenly spin-coated on the surface of the ZnO nanorod array layer; in step 1, annealing treatment is performed for 15 minutes in an air atmosphere at a temperature of 80° C. The rest is the same as Example 1.

[0056] Example 4: This example is different from Example 1 in that: in step 1, 400 μL of bacterial pigment is evenly spin-coated on the surface of the ZnO nanorod array layer; in step 1, annealing treatment is performed for 15 minutes in an air atmosphere at a temperature of 80° C. The rest is the same as Example 1.

[0057] Example 5: This example is different from Example 1 in that: in step 1, 450 μL of bacterial pigment is evenly spin-coated on the surface of the ZnO nanorod array layer; in step 1, annealing treatment is performed for 15 minutes in an air atmosphere at a temperature of 80° C. The rest is the same as Example 1.

[0058] Example 6: This example is different from Example 1 in that: in step 1, 500 μL of bacterial pigment is evenly spin-coated on the surface of the ZnO nanorod array layer; in step 1, annealing treatment is performed for 15 minutes in an air atmosphere at a temperature of 80° C. The rest is the same as Example 1.

[0059] Comparative experiment: The difference between this comparative experiment and Example 1 is that the bacterial pigment layer and the annealing treatment in step 1 are omitted. The rest is the same as Example 1.

[0060] The ultraviolet photodetector prepared in Example 2 is named FTO / ZnO NR arrays / P-V300-A80 / Au, the ultraviolet photodetector prepared in Example 3 is named FTO / ZnO NR arrays / P-V350-A80 / Au, the ultraviolet photodetector prepared in Example 4 is named FTO / ZnO NR arrays / P-V400-A80 / Au, the ultraviolet photodetector prepared in Example 5 is named FTO / ZnO NR arrays / P-V450-A80 / Au, the ultraviolet photodetector prepared in Example 6 is named FTO / ZnO NR arrays / P-V500-A80 / Au, and the ultraviolet photodetector prepared in the comparative experiment is named FTO / ZnONR arrays / Au, wherein P represents pyomelanocortin, V represents the volume of pyomelanocortin, and A80 represents the annealing temperature at 80°C.

[0061] Figure 2 The figures are scanning electron microscope images, (a) is the surface of the ZnO nanorod array layer prepared in step 1 of Example 1, (b) is the cross section of the ZnO nanorod array layer prepared in step 1 of Example 1, (c) is the surface of the FTO / ZnO nanorod array layer / bacteriochrome layer device prepared in step 1 of Example 1, and (d) is the cross section of the FTO / ZnO nanorod array layer / bacteriochrome layer device prepared in step 1 of Example 1. As can be seen from the figure, the ZnO nanorod array is uniform in size and tightly arranged, and is a typical 1-dimensional nanomaterial. The length of the ZnO nanorods in the ZnO nanorod array layer is 500nm to 1000nm, and the diameter is 50nm to 120nm. The surface of the FTO / ZnO nanorod array layer / bacteriochrome layer device is covered with a bacteriochrome layer with a thickness of 500nm to 800nm.

[0062] The work function of the ZnO nanorod array layer prepared in step 1 of Example 1 was tested to be 4.45 eV, the work function of the bacteriochrome layer coated in step 1 of Example 1 was 3.58 eV before annealing, and dropped to 3.17 eV after annealing. The bacteriochrome and the ZnO nanorod array formed an ohmic contact heterojunction, and the bacteriochrome was the electron transport layer in the heterojunction.

[0063] Example 1 Step 1 The resistivity of the bacterial pigment layer coated before and after annealing was 3.35Ω·sqr -1 Reduced to 3.05Ω·sqr after annealing -1 The carrier mobility increases from 1.02×10 3 cm 2 ·V-1 ·s -1 Increased to 1.24×10 after annealing 3 cm 2 ·V -1 ·s -1 The carrier concentration increases from 1.65×10 15 cm -3 Increased to 1.83×10 after annealing 15 cm -3 .

[0064] The metal Au electrode in the UV photodetector is connected to the negative electrode, the metal In electrode is connected to the positive electrode, and a -3V bias is applied to the circuit. -2 ~60mW·cm -2 The device was irradiated with 365nm ultraviolet light and the ultraviolet light detection effect of the photodetector was recorded.

[0065] The UV photodetector with added pyomelanocin in the embodiment and the UV photodetector without added pyomelanocin in the comparative experiment were used for comparison, and the photocurrent of the detector was recorded using a digital source meter. The light was turned on and off every 6 seconds, and the photocurrent I photo (Unit: mA) is used as a parameter to measure the effect of the photodetector and is calculated using the following formula:

[0066] I photo =I light -I dark

[0067] Among them, I light is the photocurrent in mA; I dark is the dark current in mA.

[0068] Based on the photogenerated current, the photoresponsivity R, which measures the photoelectric conversion capability, can be calculated. λ (Unit is A·W -1 , and then converted to mA·W -1 ), calculated by the following formula:

[0069] R λ =I photo / (P in S)

[0070] Among them, I photo is the photocurrent, the unit is mA; P in is the UV radiation intensity, in mW·cm -2 ; S is the irradiation area. In the embodiment, the diameter of the irradiation area is Φ = 2 mm, that is, S = 0.0314 cm 2 .

[0071] Based on the photocurrent and photoresponsivity, another parameter, detection rate D, which measures the weak light conversion capability and anti-interference capability, can be obtained. λ * (Unit: Jones), calculated by the following formula:

[0072] D λ * =R λ / (2qJ dark ) 1 / 2

[0073] Among them, R λ is the light response, the unit is mA·W -1 ; q is the elementary charge, the unit is coulomb C; J dark is the dark current in mA.

[0074] Figure 3 At -3V bias, 60mW·cm -2 IT diagrams of the ultraviolet photodetectors prepared in Examples 2 to 6 and comparative experiments under different pyomelanocortin contents under 365nm ultraviolet light; as shown in the figure, the change in the volume of pyomelanocortin deposited on the ZnO nanorod array has a significant effect on the photogenerated current. At an annealing temperature of 80°C, the initial increase in the volume of pyomelanocortin on the surface of the ZnO nanorod array led to an increase in the current, but then the current began to decrease as the pyomelanocortin further increased. Compared with the ultraviolet detector prepared in the comparative experiment, the addition of pyomelanocortin significantly improved the photoelectric performance of the ultraviolet photodetector (UV PD). When the coating volume of pyomelanocortin was 400 microliters, the photogenerated current reached a maximum value of 31.72mA. In contrast, excessive pigment coating (500 microliters) resulted in a decrease in photogenerated current. This reduction is mainly due to the increase in electron transmission distance, the increase in charge injection barrier, and the increase in device resistance, which are all consequences of the excessive thickness of the electron transport layer (ETL).

[0075] Figure 4 The photoresponsivity and detection rate of the ultraviolet photodetector prepared in Example 1 under -3V bias voltage to ultraviolet light of different optical powers, (a) is the photocurrent, (b) is the photoresponsivity and detection rate. As can be seen from the figure, the ultraviolet photodetector prepared in Example 1 has a good photocurrent response to ultraviolet light of different optical powers, and the photocurrent response to 0.80mW·cm -2 ~60mW·cm -2 When the 365nm ultraviolet light is used for detection, a photocurrent of 10.94mA to 23.04mA can be obtained, and 0.14×10 5 mA·W -1 ~4.35×10 5 mA·W -1 The photoresponsivity is 2.6×1012 Jones~1.01×10 14 Jones detection rate. Especially in weak light detection, for 0.80mW·cm -2 When the 365nm ultraviolet light was used for detection, a photocurrent of 10.94mA and a photocurrent of 4.35×10 5 mA·W -1 The photoresponsivity is 1.01×10 14 Jones's detection rate.

Claims

1. An ultraviolet photoelectric detector, characterized in that It consists of a metal Au electrode, a metal In electrode, a bacterial pigment layer, a ZnO nanorod array layer and FTO conductive glass; the metal In electrode is arranged in a frame-shaped structure on the periphery of the FTO conductive glass surface, and the inside of the metal In electrode is composed of a ZnO nanorod array layer, a bacterial pigment layer and a metal Au electrode from the FTO conductive glass surface to the top.

2. The ultraviolet photodetector according to claim 1, characterized in that The thickness of the metal Au electrode is 40nm-60nm; the thickness of the metal In electrode is 50μm-150μm, and the width is 1mm-2mm; the thickness of the bacterial pigment layer is 500nm-800nm; the thickness of the ZnO nanorod array layer is 500nm-1000nm.

3. The ultraviolet photodetector according to claim 2, characterized in that The size of the ultraviolet photoelectric detector is 2cm×2cm×(0.20-0.22)cm.

4. The ultraviolet photodetector according to claim 1, characterized in that The bacterial pigment layer is prepared from pyomelanocortin, and the molecular weight of the pyomelanocortin is 12000Da to 120000Da.

5. The method for preparing an ultraviolet photodetector according to claim 1, characterized in that It is carried out in the following steps: First, a ZnO nanorod array layer was prepared on the surface of FTO conductive glass by a hydrothermal method, and then bacterial pigment was evenly spin-coated on the surface of the ZnO nanorod array layer, and then annealed in an air atmosphere to obtain a FTO / ZnO nanorod array layer / bacterial pigment layer device; 2. A metal Au layer is prepared on the surface of the bacteriochrome layer of the FTO / ZnO nanorod array layer / bacteriochrome layer device to form a metal Au electrode, and then a coating layer with a width of 1 mm to 2 mm is scraped off around the device, and then metal In is welded to the FTO glass surface to form a metal In electrode, thereby completing the preparation method of the ultraviolet photodetector.

6. The method for preparing an ultraviolet photodetector according to claim 5, characterized in that The bacterial pigment described in step one is pyomelanocortin, and the molecular weight of pyomelanocortin is 12000Da to 120000Da; the annealing described in step one is specifically carried out in an air atmosphere and a temperature of 50°C to 90°C for 15min to 30min.

7. The method for preparing an ultraviolet photodetector according to claim 5, characterized in that The preparation of the ZnO nanorod array layer on the surface of the FTO conductive glass by the hydrothermal method described in step 1 is specifically carried out according to the following steps: ① Add anhydrous zinc acetate and diethanolamine to isopropanol, and then heat and dissolve to obtain a ZnO precursor solution; The concentration of anhydrous zinc acetate in the ZnO precursor solution is 0.05 mol·L -1 ~0.15mol·L -1 The concentration of diethanolamine in the ZnO precursor solution is 0.1 mol·L -1 ~0.3mol·L -1 ; ② The coating volume is 150μL / 4cm 2 ~300μL / 4cm 2 , spin coating the ZnO precursor solution on the conductive surface of the FTO conductive glass and annealing to obtain the FTO glass covered with the ZnO seed layer; ③ Dissolve zinc nitrate hexahydrate and hexamethylenetetramine in deionized water to obtain a ZnO growth solution; The concentration of zinc nitrate hexahydrate in the ZnO growth solution is 0.03 mol·L -1 ~0.08mol·L -1 The concentration of hexamethylenetetramine in the ZnO growth solution is 0.03 mol·L -1 ~0.08mol·L -1 ; ④ Immerse the FTO glass covered with the ZnO seed layer in the ZnO growth solution, use a hydrothermal reactor, and react for 3h to 8h at a temperature of 100℃ to 150℃. After the reactor is cooled to room temperature, take it out and rinse the surface with pure water, then blow off the surface residue with compressed air, and finally anneal to obtain the ZnO nanorod array layer.

8. The method for preparing an ultraviolet photodetector according to claim 7, characterized in that The heating and dissolving in step ① is specifically to dissolve by stirring at a temperature of 50° C. to 80° C. to form a transparent solution.

9. The method for preparing an ultraviolet photodetector according to claim 7, characterized in that The annealing in steps ② and ④ is specifically carried out in an air atmosphere at a temperature of 300° C. to 350° C. for 0.5 h to 1 h.

10. The method for preparing an ultraviolet photodetector according to claim 7, characterized in that The length of the ZnO nanorods in the ZnO nanorod array layer prepared in step ④ is 500nm-1000nm, and the diameter is 50nm-120nm.

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