Weak light detection structure and preparation method thereof

Abstract

The application provides a weak light detection structure and a preparation method thereof. The weak light detection structure comprises an insulating layer, a floating gate layer formed on the insulating layer, and an active layer formed on the floating gate layer; a surface of the insulating layer in contact with the floating gate layer is formed with a material layer as an electron trap state, the floating gate layer is composed of a matrix layer and lead sulfide quantum dots dispersed in the matrix layer, the material of the matrix layer is selected to be an insulating polymer material, and the lead sulfide quantum dots can be uniformly dispersed in the matrix layer. The scheme of the application does not require the energy level matching of the active layer and the charge storage layer, and the device mobility and stability are not affected. Meanwhile, the material of the active layer can grow on the flat surface of the floating gate layer to form a highly ordered crystalline thin film, which is beneficial to improve the device mobility and reduce the sub-threshold swing, thereby increasing the photocurrent and improving the weak light detection capability of the device.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of weak light detection, and in particular to a weak light detection structure and a preparation method thereof. BACKGROUND

[0002] Organic phototransistor (OPT) is a kind of photoactive device based on organic field effect transistor (OFET), which has all the advantages of OFET, such as good solution preparation compatibility, mechanical flexibility, chemical customization of molecular groups, etc., which are difficult to achieve in inorganic transistors. Compared with other photoactive devices such as photodiodes, OPT has excellent signal amplification effect due to its three-electrode structure, and the output signal is more diverse, which has a wider application prospect than photodiodes. Based on the above advantages, OPT is widely used in popular research fields such as near-infrared detection, optical memory storage, image recognition, color recognition, short-wave optical communication, human visual adaptation and biological bionics. Among the many parameters of OPT, the device's ability to detect weak light is an important research indicator. Higher weak light recognition capability means lower light intensity detection lower limit, which means stronger signal amplification capability and higher dynamic range recognition capability. Weak light detection not only requires the active layer to have high photosensitivity, but also requires adjustment of the device structure or components to achieve amplification of the optical signal of the device.

[0003] Currently, there are two main routes to achieve weak light detection of OPT: one is to combine OPT with external circuit to amplify the output signal, and the other is to introduce electron trap states, polymer electrets and floating gate layers to store photo-generated charges. However, integrating OPT and external circuit on the same substrate often involves multiple processes such as multiple photolithography, sacrificial layer stripping, solution spin coating, evaporation, etc., which has a complex preparation process, high industrial cost and low device yield. Introducing a charge storage layer into the device structure requires the charge storage material to have high photosensitivity, and the energy levels of the active layer and the charge storage layer need to be matched with each other. The stringent conditions make it difficult to significantly improve the weak light detection performance of the OPT structure. At the same time, the introduction of the charge storage layer also affects the transmission of the conductive channel of the active layer, making it difficult for the sub-threshold swing and working stability of the OPT to reach the original level of organic semiconductor materials. SUMMARY

[0004] One object of the present application is to reduce the impact of the introduction of the charge storage layer on the transmission of the conductive channel of the active layer, and to eliminate the need for energy level matching between the active layer and the charge storage layer.

[0005] A further object of the present application is to improve the weak light detection capability of the device.

[0006] In particular, the application provides a weak light detection structure, comprising an insulating layer, a floating gate layer formed on the insulating layer, and an active layer formed on the floating gate layer.

[0007] A surface of the insulating layer in contact with the floating gate layer is formed with a material layer as an electron trap state, the floating gate layer is composed of a matrix layer and lead sulfide quantum dots dispersed in the matrix layer, the material of the matrix layer is selected to be an insulating polymer material, and the lead sulfide quantum dots are uniformly dispersed in the matrix layer.

[0008] Optionally, the polymer material is polyvinyl cinnamate, polyvinyl alcohol, or polyvinyl pyrrolidone.

[0009] Optionally, the material of the material layer is selected to be a gate insulating layer material with an electron capture group on the surface.

[0010] Optionally, the weak light detection structure further comprises a source electrode and a drain electrode, both of which are formed above the floating gate layer and arranged at intervals.

[0011] In particular, the application also provides a preparation method of the weak light detection structure as described above, comprising the following steps:

[0012] Providing a transparent conductive substrate;

[0013] Forming an insulating layer on the transparent conductive substrate;

[0014] Applying a mixed solution mixed with a polymer material and lead sulfide quantum dots on the insulating layer to form a floating gate layer on the insulating layer;

[0015] Scraping an active layer solution for forming an active layer on the floating gate layer to form an active layer on the floating gate layer.

[0016] Optionally, in the step of applying the mixed solution mixed with the polymer material and the lead sulfide quantum dots on the insulating layer to form the floating gate layer on the insulating layer, the configuration method of the mixed solution comprises:

[0017] Mixing the lead sulfide quantum dots with a first solvent to obtain a first solution;

[0018] Mixing the polymer material with a second solvent to obtain a second solution, the second solvent being selected to be a solvent with similar polarity to the first solvent and capable of realizing molecular-level blending;

[0019] Mixing the first solution and the second solution according to a preset volume ratio to obtain the mixed solution, the mixed solution being azeotrope.

[0020] Optionally, the first solvent is selected from butylamine, and the second solvent is selected from chlorobenzene; or the first solvent is selected from cyclohexane, and the second solvent is selected from dichloromethane.

[0021] The polymer material is selected from polyvinyl cinnamate, polyvinyl alcohol, or polyvinyl pyrrolidone.

[0022] Optionally, the preset volume ratio is any value in the range of 1:4-6.

[0023] Optionally, the step of applying the mixed solution mixed with the polymer material and the lead sulfide quantum dots on the insulating layer to form a floating gate layer on the insulating layer comprises the following steps:

[0024] The mixed solution is spin-coated on the insulating layer.

[0025] The residual reagents in the mixed solution are heated and dried at a preset temperature, and photo-curing and thermal curing are performed to obtain the floating gate layer.

[0026] Optionally, the preset temperature is any value in the range of 90-120°C.

[0027] Optionally, the wavelength of the light in the photo-curing is any value in the range of 350-380 nm, and the temperature of the thermal curing is any value in the range of 80-120°C.

[0028] Optionally, the step of forming an insulating layer on the transparent conductive substrate comprises the following steps:

[0029] An insulating material layer is formed on the transparent conductive substrate.

[0030] The transparent conductive substrate with the insulating material layer formed thereon is placed in a vacuum chamber.

[0031] An aluminum source and a water source are alternately pulsed to uniformly deposit the aluminum source on the surface of the transparent conductive substrate, and the aluminum source reacts with water under heating conditions to obtain a single-layer insulating layer film.

[0032] The pulsed process is repeated multiple times to obtain a multi-layer insulating layer film, thereby obtaining a material layer.

[0033] The thickness of the single-layer insulating layer film is any value in the range of 0.05-0.2 nm.

[0034] The thickness of the multi-layer insulating layer film is any value in the range of 50-80 nm.

[0035] Optionally, after the mixed solution of the polymer material and the lead sulfide quantum dots is applied on the insulating layer to form the floating gate layer on the insulating layer, the active layer solution for forming the active layer is blade-coated on the floating gate layer to form the active layer on the floating gate layer, and the method further comprises the following step:

[0036] The source and the drain are respectively formed on two sides of the floating gate layer.

[0037] According to the scheme of the present application, the floating gate layer is formed on the insulating layer, and the floating gate layer is composed of a matrix layer and lead sulfide quantum dots, the lead sulfide quantum dots are uniformly dispersed in the matrix layer, and a material layer for serving as an electron trap state is further formed on the surface of the insulating layer, the charges generated by the light irradiation of the lead sulfide quantum dots are captured by the electron trap state, so that the weak light detection capability of the device can be greatly improved. Since the lead sulfide quantum dots are dispersed in the matrix layer, the active layer does not directly contact the lead sulfide quantum dots, and there is no vertical charge transmission between the two, so that there is no need for energy level matching, and the device mobility and stability are not affected. At the same time, the material of the active layer can grow on the flat surface of the floating gate layer to form a highly ordered crystalline thin film, which is beneficial to improve the device mobility and reduce the sub-threshold swing, thereby increasing the photocurrent and improving the weak light detection capability of the device.

[0038] Further, the weak light detection structure of the present application can achieve a minimum weak light detection capability of 0.57nW / cm 2 , a dynamic range of up to 109.47dB, and the use of photon integration effect can further improve the amplification capability of the device for weak light signals and improve the bias stability of the device. Moreover, the preparation method of the present application is simple and efficient.

[0039] The above and other objects, advantages and features of the present application will become more apparent from the following detailed description of some embodiments thereof, when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0040] Some specific embodiments of the present application will be described in detail below with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar components or parts. It should be understood by those skilled in the art that the drawings are not necessarily drawn to scale. In the drawings:

[0041] Figure 1 a schematic structural diagram of a weak light detection structure according to an embodiment of the present application is shown;

[0042] Figure 2 a schematic flow chart of a preparation method of a weak light detection structure according to an embodiment of the present application is shown;

[0043] Figure 3A schematic flow chart of a method for forming an insulating layer on a transparent conductive substrate according to an embodiment of the present application is shown;

[0044] Figure 4 A schematic flow chart of a method for configuring a mixed solution according to an embodiment of the present application is shown;

[0045] Figure 5 A schematic flow chart of a method for forming a floating gate layer on an insulating layer is shown;

[0046] Figure 6 A photograph of a transparent conductive substrate with a floating gate layer formed thereon according to an embodiment of the present application is shown;

[0047] Figure 7 A polarized light microscope image of a weak light detection structure according to an embodiment of the present application is shown;

[0048] Figure 8 A transfer characteristic curve of a weak light detection structure according to an embodiment of the present application is shown;

[0049] Figure 9 An atomic force microscope image of a floating gate layer according to an embodiment of the present application is shown;

[0050] Figure 10 A high angle annular dark field scanning transmission electron microscope image of a floating gate layer according to an embodiment of the present application is shown;

[0051] Figure 11 A cross-sectional scanning electron microscope image of a floating gate layer according to an embodiment of the present application is shown;

[0052] Figure 12 A transmission electron microscope image of a floating gate layer according to an embodiment of the present application is shown;

[0053] Figure 13 A scanning schematic of a Kelvin probe force microscope of a floating gate layer according to an embodiment of the present application is shown;

[0054] Figure 14 A graph showing the variation of surface potential of a floating gate layer with time under light conditions according to an embodiment of the present application is shown;

[0055] Figure 15 A graph showing the variation of surface potential of a floating gate layer with time under no light conditions according to an embodiment of the present application is shown;

[0056] Figure 16 A graph showing the variation of current of a floating gate layer with time according to an embodiment of the present application is shown;

[0057] Figure 17Fig. 1 shows weak light detection performance data under illumination conditions according to an embodiment of the present application;

[0058] Fig. 1 shows weak light detection performance data under illumination conditions according to an embodiment of the present application; DETAILED DESCRIPTION

[0059] Figure 1 Fig. 1 shows weak light detection performance data under illumination conditions according to an embodiment of the present application; Figure 1 As shown in the figure, the weak light detection structure includes an insulating layer, a floating gate layer and an active layer, the floating gate layer is formed on the insulating layer, and the active layer is formed on the floating gate layer. The surface of the insulating layer in contact with the floating gate layer is formed with a material layer as an electron trap state. The floating gate layer is composed of a matrix layer and lead sulfide quantum dots (abbreviated as PbSCQDs) dispersed in the matrix layer, the material of the matrix layer is selected to be an insulating polymer material, and the lead sulfide quantum dots can be uniformly dispersed in the matrix layer.

[0060] According to the scheme of the present application, by forming the floating gate layer on the insulating layer, and the floating gate layer is composed of the matrix layer and the lead sulfide quantum dots, the lead sulfide quantum dots are uniformly dispersed in the matrix layer, and the material layer for the electron trap state is also formed on the surface of the insulating layer, the charges generated by the light radiation of the lead sulfide quantum dots are captured by the electron trap state, so that the weak light detection capability of the device can be greatly improved. Since the lead sulfide quantum dots are dispersed in the matrix layer, the active layer does not directly contact the lead sulfide quantum dots, and there is no vertical charge transmission between the two, so there is no need for energy level matching, and the device mobility and stability are not affected. At the same time, the material of the active layer can grow on the flat surface of the floating gate layer to form a highly ordered crystalline thin film, which is beneficial to improve the device mobility and reduce the sub-threshold swing, thereby increasing the photocurrent and improving the weak light detection capability of the device.

[0061] In one embodiment, the polymer material is selected to require that the lead sulfide quantum dots can be uniformly dispersed therein, for example, polyvinyl alcohol cinnamate (abbreviated as PVCn), polyvinyl alcohol or polyvinyl pyrrolidone. The material of the material layer can be selected, for example, from gate insulating layer materials such as aluminum oxide, photoetching negative resist material SU-8, polyvinyl alcohol, etc. with electron capture groups such as -OH, -NH2, -COOH, etc. The weak light detection structure further includes a source electrode and a drain electrode, both of which are formed above the floating gate layer and arranged apart.

[0062] According to the scheme of the embodiment of the present application, the weak light detection structure can achieve a minimum of 0.57nW / cm 2The weak light detection capability is improved, the dynamic range is up to 109.47dB, the photon integration effect is used, the amplification capability of the device for the weak light signal is improved again, and the bias stability of the device is improved.

[0063] Figure 2 A schematic flow chart of a preparation method of a weak light detection structure according to one embodiment of the present application is shown. As shown in the figure, Figure 2 The weak light detection structure is the aforementioned weak light detection structure, and the preparation method comprises the following steps:

[0064] Step S100, providing a transparent conductive substrate;

[0065] Step S200, forming an insulating layer on the transparent conductive substrate;

[0066] Step S300, applying a mixed solution mixed with a polymer material and lead sulfide quantum dots on the insulating layer to form a floating gate layer on the insulating layer;

[0067] Step S400, coating an active layer solution for forming an active layer on the floating gate layer to form an active layer on the floating gate layer.

[0068] In the step S100, the transparent conductive substrate may be ITO glass, for example. The transparent conductive glass needs to be cleaned. In one embodiment, the cleaning method is as follows: the ITO glass cut in advance is vertically placed on a cleaning rack, and acetone, isopropyl alcohol, ethanol and deionized water are poured in respectively, and ultrasonic is performed for a certain time, for example, 10min, 20min or 30min, or any time within 10-30min. After being dried by nitrogen, the surface is bombarded by an oxygen plasma adhesive remover (O-Plasma) to remove the residual organic matter on the surface and increase the hydrophilicity.

[0069] Figure 3 A schematic flow chart of a method for forming an insulating layer on a transparent conductive substrate according to one embodiment of the present application is shown. As shown in the figure, Figure 3 The step S200 comprises the following steps:

[0070] Step S210, forming an insulating material layer on the transparent conductive substrate;

[0071] Step S220, placing the transparent conductive substrate with the insulating material layer formed thereon in a vacuum chamber;

[0072] Step S230, alternately pulsing an aluminum source and a water source respectively to uniformly deposit the aluminum source on the surface of the transparent conductive substrate, and reacting with water under heating to obtain a single-layer insulating layer film;

[0073] Step S240, repeating the pulsing for multiple times to obtain a multi-layer insulating layer film, thereby obtaining the material layer.

[0074] In step S210, the material of the insulating material layer can be, for example, Parylene. The step can be performed by using a Parylene encapsulation evaporator (KR350SH) to evaporate the insulating material layer. In the step, a certain amount of Parylene powder is taken and placed in a vacuum chamber of the Parylene encapsulation evaporator, so that the insulating material layer is formed on the transparent conductive substrate with a thickness of 1-2 μm, for example, 1.5 μm.

[0075] In steps S220-S240, the material layer can be obtained by using an atomic deposition system (ALD, MNT-S100-L3) of Jiangsu Mai Naide Micro-Nano Technology Co., Ltd. In step S220, the temperature in the vacuum chamber can be, for example, 150°C, 200°C, or 250°C, or any temperature value within the range of 150-250°C.

[0076] In step S230, the aluminum source can be, for example, trimethylaluminum. The material of the single-layer insulating layer film is Al2O3, and the thickness of the single-layer insulating layer film can be, for example, 0.05 nm, 0.1 nm, 0.15 nm, or 0.2 nm, or any value within the range of 0.05-0.2 nm.

[0077] In step S240, the number of repeated pulses can be set as needed, for example, 500 times, 600 times, or 700 times. Nitrogen gas can be used as a carrier gas to purge the excess aluminum source and water source during the repeated pulses. The thickness of the multi-layer insulating layer film can be, for example, 50 nm, 60 nm, 70 nm, or 80 nm, or any other value within the range of 50-80 nm. The material layer serves as an electron trap state.

[0078] Figure 4 A schematic flowchart of a method for configuring a mixed solution according to an embodiment of the present application is shown. As shown in Figure 4 The method for configuring the mixed solution includes:

[0079] In step S301, lead sulfide quantum dots are mixed with a first solvent to obtain a first solution.

[0080] In step S302, a polymer material is mixed with a second solvent to obtain a second solution, and the second solvent is selected to be a solvent with a polarity similar to that of the first solvent and capable of realizing molecular-level blending.

[0081] In step S303, the first solution and the second solution are mixed according to a preset volume ratio to obtain a mixed solution, and the mixed solution is azeotrope.

[0082] The first solvent and the second solvent need to be selected as solvents with similar polarity and capable of realizing molecular-level blending, so as to finally form azeotrope with the mixed solution. In an embodiment, the first solvent is selected as butylamine, and the second solvent is selected as chlorobenzene. In another embodiment, the first solvent can be selected as cyclohexane, and the second solvent is selected as dichloromethane.

[0083] The polymer material can be selected as polyvinyl cinnamate, polyvinyl alcohol or polyvinyl pyrrolidone, for example. The preset volume ratio can be 1:4, 1:5 or 1:6, or any value in the range of 1:4-6.

[0084] In a specific embodiment, in step S301, the mass of the lead sulfide quantum dots is 15 mg, and the volume of the first solvent is 50 μL. After mixing the two to obtain the first solution, it is placed in a glove box for standby. In step S302, the polymer material is selected as polyvinyl cinnamate powder. 60 mg or 30 mg of the polymer material is weighed, and 1 ml of chlorobenzene reagent is measured. After stirring for a certain period of time, the second solution is obtained. In step S303, the volume ratio of the first solution to the second solution is 1:5, for example, 50 μL of the first solution and 250 μL of the second solution. The thickness of the finally formed floating gate layer is 1 μm.

[0085] Figure 5 A schematic flowchart of a method for forming a floating gate layer on an insulating layer is shown. As shown in Figure 5 The step S300 includes:

[0086] In step S310, the mixed solution is spin-coated on the insulating layer.

[0087] In step S320, the residual reagents in the mixed solution are heated and dried at a preset temperature, and photo-curing and thermal curing are performed to obtain the floating gate layer.

[0088] In step S320, the preset temperature is 90°C, 100°C, 110°C or 120°C, or any other value in the range of 90-120°C. The wavelength of the light in photo-curing can be 350 nm, 360 nm, 370 nm or 380 nm, or any other value in the range of 350-380 nm. The temperature of thermal curing can be 80°C, 90°C, 100°C, 110°C or 120°C, or any other value in the range of 80-120°C.

[0089] Between step S300 and step S400, a source electrode and a drain electrode are also formed on the floating gate layer. The source electrode and the drain electrode can be formed by, for example, covering a metal mask on the transparent conductive substrate after step S300, and inverting it in a high-vacuum chamber of a thermal evaporation coater (the vacuum degree is about 10 -5The silver is selected as the source-drain electrode, the length-width ratio of the channel is L:W=120:600 μm, the thickness of the electrode is 45 nm, and the evaporation rate is 0.04 nm / s. Subsequently, the work function of the electrode needs to be adjusted to form a Schottky contact between the silver and the material of the active layer. A small molecule modifier PFBT is dissolved in ethanol to prepare a modification solution with a concentration of 1.5 μL / mL. The substrate containing the electrode is immersed in the modification solution for 5 min, and then dried with nitrogen for standby. PFBT is the abbreviation of poly[(9,9-dioctylfluorene-2,7-diyl)-alt-co-(1,4-benzo-{2,1',3}-thiadiazole)].

[0090] In step S400, the active layer can be a C8-BTBT crystal thin film layer. The doctoring is a solution doctoring method. A previously modified FTS hydrophobic doctor blade is used to doctor at a certain speed (for example, 50 μm / s, 100 μm / s, 150 μm / s or 200 μm / s). The C8-BTBT crystals grow slowly above the floating gate layer, and finally a highly ordered C8-BTBT crystal thin film is obtained.

[0091] Figure 6 A photograph of a transparent conductive substrate with a floating gate layer according to an embodiment of the present application is shown. The substrate is prepared by Figure 6 It can be seen that the floating gate layer appears to be a tea-colored semi-transparent state (the color cannot be seen because the photograph has been processed in grayscale). This indicates that the lead sulfide quantum dots are uniformly dispersed in the polymer material.

[0092] Figure 7 A polarized light microscope image of a weak light detection structure according to an embodiment of the present application is shown. The substrate is prepared by Figure 7 It can be seen that the large-area C8-BTBT crystal thin film formed by doctoring is uniformly oriented. Figure 8 A transfer characteristic curve of a weak light detection structure according to an embodiment of the present application is shown. As Figure 8 shown, the drain voltage (V DS ) is -2 V, and the low-voltage OFET characteristic subthreshold swing is 99.2 mV / dec (close to the theoretical limit of 60 mV / dec).

[0093] Figure 9 An atomic force microscope image of a floating gate layer according to an embodiment of the present application is shown. The substrate is prepared by Figure 9 It can be seen that the average roughness of the floating gate layer is 1.5 nm, and the overall is relatively flat. Figure 10 A high-angle annular dark field scanning transmission electron microscope image of a floating gate layer according to an embodiment of the present application is shown. The substrate is prepared by Figure 10 It can be seen that there is no obvious boundary between the quantum dots and the polymer, which indicates that the PbS CQDs and the PVCn are blended, and the quantum dots are fully dispersed in the polymer.Figure 11 A cross-sectional scanning electron microscope image of the floating gate layer is shown according to an embodiment of the present application. It can be seen that the PbS CQDs inside the floating gate layer are clearly visible, and the sizes of these quantum dots are close and uniformly dispersed. Figure 11 Figure 12 A transmission electron microscope image of the floating gate layer is shown according to an embodiment of the present application. It can be seen that there is no obvious agglomeration in this region, and from the inset image, it can be seen that the PbS CQDs are not only uniformly dispersed, but also have obvious lattice diffraction fringes, indicating that the PbS CQDs are arranged in a high order, and the blending layer achieves uniform distribution of the quantum dots. In summary, it can be seen that there is no deposition and aggregation of PbS CQDs inside the blending layer (floating gate layer), and the PbS CQDs are uniformly distributed in all directions of the blending layer. From the perspective of morphology, it is feasible to increase the specific surface area and incident light utilization of the PbS CQDs by polymer blending to increase the light response capability of the OPT device. Figure 12

[0094] In order to verify the response of the blending layer to light, the surface potential under light was characterized by using a Kelvin scanning probe microscope (SKPM). Figure 13 A schematic diagram of the Kelvin scanning probe microscope scanning of the floating gate layer is shown according to an embodiment of the present application. Figure 14 A graph showing the trend of the surface potential of the floating gate layer over time under light is shown according to an embodiment of the present application. It can be seen that the surface potential of the floating gate layer has decreased significantly, and the surface potential of the blending layer has decreased from -0.1 V to -0.45 V in a light time of 3000 s, which is about 0.35 V, which means that the forward shift of the OFET transfer characteristic curve makes the photocurrent significantly increase. Figure 14 A graph showing the trend of the surface potential of the floating gate layer over time under no light is shown according to an embodiment of the present application. It can be seen that the surface potential of the floating gate layer has almost no change under no light. Figure 15 A graph showing the trend of the surface potential of the floating gate layer over time under no light is shown according to an embodiment of the present application. It can be seen that the surface potential of the floating gate layer has almost no change under no light. Figure 15 A graph showing the trend of the surface potential of the floating gate layer over time under no light is shown according to an embodiment of the present application. It can be seen that the surface potential of the floating gate layer has almost no change under no light. Figure 16 A graph showing the trend of the surface potential of the floating gate layer over time under no light is shown according to an embodiment of the present application. It can be seen that the surface potential of the floating gate layer has almost no change under no light. Figure 16 It can be seen that the floating gate layer has high photosensitivity and working stability.

[0095] The foregoing weak light detection structure has numerous potential applications in the field of light detection, because the floating gate layer can greatly increase the photocurrent of the device, and the distribution of the PbS CQDs inside the floating gate layer is ordered, which increases the volume of the photosensitive layer (relative to the PbS CQDs film) and the specific surface area of the quantum dots. Figure 17 Weak light detection performance data under light is shown according to an embodiment of the present application. It can be seen that the photocurrent of the device is significantly increased under light. Figure 17 ​​It can be known that the weak light detection structure can detect weak light as low as 0.003 lx, the dynamic range is increased from 69.63 to 109.47 dB, and the light sensing capability of the OPT is greatly improved. The higher weak light recognition capability of the OPT, i.e. the lower lower limit of light intensity detection, the stronger signal amplification capability, and the higher dynamic range recognition capability, widen the working field of the device to the dim environment at night, so that the weak light OPT device not only has excellent light detection parameters, but also extends the working conditions of the OPT device to the complex light environment while retaining many applications of the OPT device. Whether it is a bright day or a weak light night, the weak light OPT can work normally.

[0096] The embodiment of the present application provides a high-efficiency and simple weak light detection structure, solves the compatibility problem of the photosensitive layer and the active layer, realizes the detection of extremely weak light, provides a new idea for the current weak light detection field, provides a feasible scheme for improving the light response of the OPT device, and the high-efficiency weak light detector can be applied to the fields of human eye visual cell simulation and dark vision imaging.

[0097] At this point, those skilled in the art should recognize that although the present application has been shown and described in detail in the above embodiments, many other variations or modifications can be directly determined or deduced according to the disclosed content without departing from the spirit and scope of the present application. Therefore, the scope of the present application should be understood and recognized as covering all these other variations or modifications.

Claims

1. A weak light detection structure, characterized by, The insulating layer, a floating gate layer formed on the insulating layer, and an active layer formed on the floating gate layer; A surface of the insulating layer in contact with the floating gate layer is formed with a material layer as an electron trap state, the floating gate layer is composed of a matrix layer and lead sulfide quantum dots dispersed in the matrix layer, the material of the matrix layer is selected as an insulating polymer material, and the lead sulfide quantum dots are uniformly dispersed in the matrix layer; The material of the material layer is selected as a gate insulating layer material with electron capture groups on the surface.

2. The weak light detecting structure according to claim 1, wherein, The polymer material is polyvinyl cinnamate, polyvinyl alcohol, or polyvinyl pyrrolidone.

3. The weak light detecting structure according to claim 1, wherein, The source and the drain are both formed above the floating gate layer and arranged at intervals.

4. A method of manufacturing a weak light detecting structure according to any of claims 1-3, characterized in that, The method comprises the following steps: Providing a transparent conductive substrate; Forming an insulating layer on the transparent conductive substrate; Applying a mixed solution mixed with a polymer material and lead sulfide quantum dots on the insulating layer to form a floating gate layer on the insulating layer; Scratching an active layer solution for forming an active layer on the floating gate layer to form an active layer on the floating gate layer.

5. The preparation method according to claim 4, characterized in that, In the step of applying the mixed solution mixed with the polymer material and the lead sulfide quantum dots on the insulating layer to form the floating gate layer on the insulating layer, the configuration method of the mixed solution comprises: Mixing the lead sulfide quantum dots with a first solvent to obtain a first solution; Mixing the polymer material with a second solvent to obtain a second solution, the second solvent being selected as a solvent with a polarity similar to that of the first solvent and capable of realizing molecular-level blending; Mixing the first solution and the second solution according to a preset volume ratio to obtain the mixed solution, the mixed solution being azeotrope.

6. The production method according to claim 5, wherein The first solvent is selected as butylamine, and the second solvent is selected as chlorobenzene; or the first solvent is selected as cyclohexane, and the second solvent is selected as dichloromethane; The polymer material is selected as polyvinyl cinnamate, polyvinyl alcohol, or polyvinyl pyrrolidone; The preset volume ratio is any value in the range of 1:4-6.

7. The preparation method according to claim 5, characterized in that, The step of applying the mixed solution mixed with the polymer material and the lead sulfide quantum dots on the insulating layer to form the floating gate layer on the insulating layer comprises the following steps: Spinning the mixed solution on the insulating layer; Heating and drying the residual reagents in the mixed solution at a preset temperature, and performing light curing and thermal curing to obtain the floating gate layer; The preset temperature is any value in the range of 90-120℃; The wavelength of the light in the light curing is any value in the range of 350-380 nm, and the temperature of the thermal curing is any value in the range of 80-120℃.

8. The preparation method according to claim 5, characterized in that, The step of forming the insulating layer on the transparent conductive substrate comprises the following steps: Forming an insulating material layer on the transparent conductive substrate; Placing the transparent conductive substrate with the insulating material layer in a vacuum chamber; Alternately pulsing an aluminum source and a water source to uniformly deposit the aluminum source on the surface of the transparent conductive substrate, and reacting the aluminum source with water under heating conditions to obtain a single-layer insulating layer film; Repeating the pulsing multiple times to obtain a multi-layer insulating layer film, thereby obtaining the material layer; The single-layer insulating layer film has a thickness ranging from any value in 0.05-0.2nm; The multi-layer insulating layer film has a thickness ranging from any value in 50-80nm.

9. The production method according to any one of claims 4 to 8, characterized by, After the step of applying the mixed solution mixed with the polymer material and the lead sulfide quantum dots on the insulating layer to form the floating gate layer on the insulating layer, the method further comprises the following step: Forming a source electrode and a drain electrode on two sides of the floating gate layer, respectively.

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