Liquid level detector based on photoelectric detection and preparation method thereof

Abstract

The invention relates to the field of liquid level detection, in particular to a liquid level detector based on photoelectric detection and a preparation method thereof. The liquid level detector based on photoelectric detection comprises a light source, an embedded processor, a light emitting diode dimming chip, a photoelectric detector and a 24-bit high-precision ADC. Wherein the photoelectric detector is an organic photoelectric detector or a Si-based photoelectric detector, the photoelectric detector is used for carrying out photoelectric conversion, the purpose of measuring the water level is achieved, through the use of the photoelectric detector, the precision and stability of water level detection can be improved, and the influence of the outside on the liquid level detector is reduced; and the application range of the liquid level detector is widened.

Description

Technical Field

[0001] The invention relates to the field of liquid level detection, and in particular to a liquid level detector based on photoelectric detection and a preparation method thereof. Background Art

[0002] As a key device for monitoring and controlling water levels, liquid level detectors play an important role in many fields, such as industrial fields such as petrochemicals and natural gas, as well as in daily life such as water tanks, coffee machines, and different equipment used for in vitro diagnosis during medical treatment, covering almost all areas of people's daily production and life.

[0003] Liquid level detectors are based on the principle that the physical property difference of the materials on both sides of the liquid level interface or the change of the relevant physical parameters caused by the liquid level change is realized. Liquid level detectors have changed from traditional mechanical to automated electronic measurement technology. With the development of electronic technology and signal processing technology, they can also be combined with new electronic technologies such as microelectronics, calculators, sensors, etc. to realize liquid level detection. Liquid level measurement technology is gradually developing in the direction of integration, intelligence, and miniaturization.

[0004] According to the different measurement methods, liquid level detectors can be divided into contact and non-contact types. The contact measurement technology includes float water level measurement and capacitance water level measurement. The non-contact measurement technology includes ultrasonic water level measurement and optical water level detection.

[0005] However, the liquid level detectors currently on the market are affected to varying degrees by factors such as buoyancy, friction, temperature, humidity, and pressure, and have poor anti-interference capabilities, which affects the accuracy of detector detection. At the same time, whether the detectors use contact or non-contact measurement methods, they need to be in a humid environment for a long time. Water rust and corrosion are prone to occur on the surface of the detector, which affects its use and the emission of detection signals such as sound waves and light signals, thereby affecting its water level detection results and reducing its reliability.

[0006] If the detector is damaged, it will be difficult to detect with precision instruments, the electronic components will suffer great losses, and the manufacturing cost will be high, which limits the application scenarios of the liquid level detector.

[0007] At present, photodetector technology can integrate high sensitivity, high response speed, low noise and high integration. Photodetector is a key semiconductor device that can convert optical signals into electrical signals. Due to its small size and low cost, it has a wide range of applications in many fields.

[0008] Therefore, the researchers considered applying photoelectric detection technology to liquid level detection equipment, which can not only improve the accuracy and anti-interference ability of the liquid level detector, but also meet the non-contact measurement mode, avoiding the liquid level detector from directly contacting the liquid surface and being affected by buoyancy, friction, temperature and other conditions. However, there is currently a lack of such a low-cost, high-precision liquid level detector on the market that measures the liquid level through photoelectric signal conversion. Summary of the invention

[0009] The object of the present invention is to provide a liquid level detector based on photoelectric detection;

[0010] Another object of the present invention is to provide a method for preparing a liquid level detector based on photoelectric detection.

[0011] The technical solution adopted to achieve the purpose of the present invention is:

[0012] A liquid level detector based on photoelectric detection, also referred to as a photoelectric liquid level detector, comprises:

[0013] A light emitting diode emits light waves to the water surface being measured;

[0014] A light emitting diode dimming chip (model: TPS92200D1DDCR), used to control the working parameters of the light emitting diode;

[0015] Photoelectric detector, used to receive light waves reflected from the water surface and convert the received light waves into electrical signals;

[0016] A 24-bit high-precision ADC (model: ADS1232) receives the electrical signal and performs analog-to-digital conversion;

[0017] The embedded processor (model: STM32F103RCT6) receives the digital signal after analog-to-digital conversion and calculates the water level based on the digital signal;

[0018] Wherein, the photodetector is a silicon-based photodetector or an organic photodetector.

[0019] Specifically, the Si-based photodetector models are 2DU-6 and 2CU-84;

[0020] Further, the photodetector is an organic photodetector, which includes a transparent rigid conductive substrate and / or a bottom electrode, an electron transport layer, a modification layer, a photoactive layer, a hole transport layer and a top electrode arranged from bottom to top; or a transparent rigid conductive substrate and / or a bottom electrode, a hole transport layer, a photoactive layer, an electron transport layer and a top electrode arranged from bottom to top;

[0021] Furthermore, the photoactive layer is a thin film formed by blending a polymer donor and an organic acceptor; the polymer donor includes but is not limited to one or more of P3HT, PBDB-T, PM6, and PCE-10; the organic acceptor is a non-fullerene acceptor;

[0022] Further, the receptor includes but is not limited to at least one of ITIC, IHIC, Y6, Y6-D, CH17, IEICO-4F, COTIC-4F, PDTTIC-4F, CH22, and CH23;

[0023] Further, the polymer donor is PM6, and the acceptor is at least one of Y6, CH22, and CH23;

[0024] Further, the polymer donor is PM6, and the organic acceptor is Y6;

[0025] Furthermore, the mass ratio of the polymer donor to the organic acceptor is 1:1-1:100, so as to achieve absorption of light of different wavelengths by the photoactive layer, thereby improving the overall performance of the device;

[0026] Further, the mass ratio of the polymer donor to the organic acceptor is 1:1;

[0027] Further, the photoactive layer has a thickness of 10nm-200nm;

[0028] Further, the transparent rigid conductive substrate includes but is not limited to at least one of ITO, FTO, AZO, GZO conductive glass, metal nanowire substrate and highly transparent metal film substrate;

[0029] Further, the bottom electrode includes but is not limited to at least one of indium tin oxide, metal nanowires, carbon nanotubes, conductive polymers, metal grids, and graphene;

[0030] Further, the top electrode includes but is not limited to at least one of silver, gold, lithium, calcium, strontium, barium, indium, magnesium, aluminum, and copper;

[0031] Further, the electron transport layer is at least one of ZnO nanoparticles, ZnO nanocrystals, TiO2, SnO2, WO3, and PDINO;

[0032] Furthermore, the hole transport layer includes but is not limited to MoO3, PEDOT:PSS, CuO x 、WO3、NiO x , SAM-2PACz;

[0033] By using different types of electron transport layers and hole transport layers, the leakage current of the organic photodetector can be adjusted, thereby improving the dark current of the organic photodetector under the working bias and enhancing the detection capability of the organic photodetector;

[0034] Furthermore, the modification layer includes but is not limited to at least one of PFN-Br, PEIE, and PFN / PFBT.

[0035] The photoelectric liquid level detector uses a light-emitting diode (1W, red light, wavelength 620-660nm) as a light source, and receives the reflected light of the measured liquid surface through a photoelectric detector. The output current of the photoelectric detector is proportional to the strength of the received reflected light. The output current of the photoelectric detector is collected by a current-to-voltage conversion circuit combined with a 24-bit high-precision ADC, and the measured liquid level, that is, the distance between the detector and the water surface, can be obtained by conversion.

[0036] An embedded processor is used to generate a 17Hz 50% duty cycle PWM wave to drive the dimming chip. The light-emitting diode is driven on and off to form a modulated light source. The difference in the output current of the photodetector collected when the light-emitting diode is on and off is used to characterize the measured liquid level. The technology of modulating the light source can effectively shield the interference caused by ambient light.

[0037] The photoelectric liquid level detector is connected to the light emitting diode drive circuit by using the PA4 IO port of the embedded processor; the light emitting diode drive circuit is connected to the light emitting diode through the Jled (2-pin single-row needle with a 2.54mm pitch) connector; the photoelectric detector is connected to the current-voltage conversion circuit through the Jsen (2-pin single-row needle with a 2.54mm pitch) connector; the voltage-current conversion circuit is connected to the ADC through the R16 resistor; the ADC is connected to the embedded processor through PA1, PA5, PA6, PA7, PA8, PA11, and PA12.

[0038] The present application also provides a method for preparing a photoelectric liquid level detector, wherein the photoelectric detector used is an organic photoelectric detector as described above:

[0039] S1. Transparent rigid conductive substrate and / or bottom electrode preparation:

[0040] Ultrasonic cleaning of the transparent rigid conductive substrate and / or the bottom electrode is performed with glass cleaning liquid, deionized water, acetone, and isopropanol in sequence, and then the surface of the transparent rigid conductive substrate and / or the bottom electrode is dried with a nitrogen gun, irradiated in an ultraviolet ozone treatment device, and placed in a glass culture dish for standby use;

[0041] Further, irradiation was performed in a UV-ozone treatment device for 15 min;

[0042] S2. Preparation of electron transport layer:

[0043] Dissolving zinc acetate in 2-methoxyethanol, adding ethanolamine, stirring, spin-coating the prepared solution onto a transparent rigid conductive substrate and / or a bottom electrode, and performing annealing to obtain a ZnO electron transport layer;

[0044] Further, 0.05 g of zinc acetate was dissolved in 2 mL of 2-methoxyethanol, and 14 uL of ethanolamine was added, and stirred for 6 hours. The prepared solution was spin-coated at 4000 rpm onto a transparent rigid conductive substrate and / or a bottom electrode, and annealed at 200 ° C for 1 hour to obtain a ZnO electron transport layer;

[0045] S3. Preparation of interface layer (modification layer):

[0046] PFN-Br was dissolved in methanol and stirred for 6 hours, and the prepared solution was spin-coated on the electron transport layer to obtain a PFN-Br interface layer;

[0047] Further, 1 g of PFN-Br was dissolved in 2 mL of methanol and stirred for 6 h, and the prepared solution was spin-coated onto the electron transport layer at 5000 rpm to obtain a PFN-Br interface layer;

[0048] S4. Preparation of active layer:

[0049] The polymer donor and the organic acceptor are dissolved in a chloroform solvent at a mass ratio of 1:1, and the prepared solution is spin-coated onto the PFN-Br interface layer and annealed to obtain a photoactive layer;

[0050] Further, PM6:Y6 was dissolved in chloroform solvent at a mass ratio of 1:1, with a PM6 concentration of 6 mg / mL, at 40°C for 5 hours, and the prepared solution was spin-coated onto the PFN-Br interface layer at 2000 rpm and annealed at 100°C for 10 minutes to obtain a PM6:Y6 photoactive layer;

[0051] S4. Preparation of hole transport layer:

[0052] A hole transport layer is evaporated on the photoactive layer;

[0053] Furthermore, the hole transport layer has a thickness of 5 nm;

[0054] S5. Evaporation of top electrode:

[0055] A top electrode Ag is evaporated on the hole transport layer to obtain an organic photodetector device;

[0056] Further, the thickness of the top electrode Ag is 200nm;

[0057] S6. Organic photoelectric liquid level detector circuit assembly.

[0058] Compared with the prior art, the present invention has the following beneficial effects:

[0059] 1. By using silicon-based photodetectors or organic photodetectors, the liquid level detector can measure the water level by light absorption and photoelectric conversion, so as to understand the water level changes; such a design makes the photoelectric liquid level detector do not need to contact the liquid surface, avoiding the influence of water buoyancy on the photoelectric liquid level detector, and also preventing the surface of the photoelectric liquid level detector from rusting or being corroded by liquid. In the process of water level measurement, it has stronger resistance to external interference and wider application range.

[0060] 2. The use of organic photoelectric detectors reduces the preparation cost of liquid level detectors. The raw materials used are widely and easily available, and the assembly structure is simple. Organic photoelectric detectors themselves have the advantages of being small and light, flexible, low energy consumption, and high sensitivity. When used in liquid level detectors, the use effect can better meet the requirements of water level detection and can improve the measurement accuracy and stability of liquid level detectors.

[0061] 3. The photoelectric liquid level detector in this application can also use a silicon-based photoelectric detector. The technology of silicon-based photoelectric detectors is more mature than that of organic photoelectric detectors, and the manufacturing process is relatively simple and low-cost. It is easy to mass produce and can currently be directly purchased for use, reducing the preparation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] Figure 1 This is a schematic diagram of the photoelectric liquid level detector of the present invention measuring the liquid level;

[0063] Figure 2 This is a schematic diagram of the circuit of the photoelectric liquid level detector of the present invention;

[0064] Figure 3 This is a schematic diagram of the light emitting diode driving circuit of the present invention;

[0065] Figure 4 This is a schematic diagram of the current-voltage conversion circuit of the present invention;

[0066] Figure 5 This is the schematic diagram of the ADC interface circuit of the present invention;

[0067] Figure 6 EQE diagram of the organic photodetector of the present invention and the commercial Si photodetector;

[0068] Figure 7 Spectral responsivity diagram of organic photodetector and commercial Si photodetector in the present invention technology;

[0069] Figure 8 JV curve test diagram of the organic photodetector and commercial Si photodetector in the dark state in the technology of the present invention;

[0070] Fig. 9 Detectivity diagram of organic photodetectors and commercial Si photodetectors in the present invention technology;

[0071] Fig.10 Response time diagram of organic photodetector and commercial Si photodetector to 650nm light in the present invention technology;

[0072] Fig.11 A diagram showing the relationship between liquid level and output current in the liquid level detection current of the organic photodetector and the commercial Si photodetector in the technology of the present invention. DETAILED DESCRIPTION

[0073] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0074] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0075] Example 1 Preparation of organic photodetector PM6:Y6

[0076] S1. Transparent rigid conductive substrate and / or bottom electrode preparation:

[0077] The transparent rigid conductive substrate and / or the bottom electrode are ultrasonically cleaned with glass cleaning liquid, deionized water, acetone, and isopropanol in sequence, and then the surface of the transparent rigid conductive substrate and / or the bottom electrode is blown dry with a nitrogen gun, irradiated in a UV ozone treatment device for 15 minutes, and placed in a glass culture dish for standby use;

[0078] S2. Preparation of electron transport layer:

[0079] 0.05 g of zinc acetate was dissolved in 2 mL of 2-methoxyethanol, and 14 uL of ethanolamine was added, and the mixture was stirred for 6 hours. The prepared solution was spin-coated at 4000 rpm onto a transparent rigid conductive substrate and / or a bottom electrode, and annealed at 200 ° C for 1 hour to obtain a ZnO electron transport layer;

[0080] S3. Preparation of interface layer:

[0081] 1 g PFN-Br was dissolved in 2 mL methanol and stirred for 6 h. The prepared solution was spin-coated onto the electron transport layer at 5000 rpm to obtain a PFN-Br interface layer.

[0082] S4. Preparation of active layer:

[0083] PM6:Y6 was dissolved in chloroform solvent at a mass ratio of 1:1, with a PM6 concentration of 6 mg / mL, at 40°C for 5 hours, and the prepared solution was spin-coated onto the PFN-Br interface layer at 2000 rpm and annealed at 100°C for 10 minutes to obtain a PM6:Y6 active layer;

[0084] S4. Preparation of hole transport layer:

[0085] A 5nm thick hole transport layer was evaporated on the photoactive layer;

[0086] S5. Evaporation of top electrode:

[0087] A 200nm thick top electrode Ag layer is evaporated on the hole transport layer to obtain an organic photodetector device.

[0088] Example 2 Preparation of organic photodetector PM6:CH22

[0089] S1. Transparent rigid conductive substrate and / or bottom electrode preparation:

[0090] The transparent rigid conductive substrate and / or the bottom electrode are ultrasonically cleaned with glass cleaning liquid, deionized water, acetone, and isopropanol in sequence, and then the surface of the transparent rigid conductive substrate and / or the bottom electrode is blown dry with a nitrogen gun, irradiated in a UV ozone treatment device for 15 minutes, and placed in a glass culture dish for standby use;

[0091] S2. Preparation of electron transport layer:

[0092] 0.05 g of zinc acetate was dissolved in 2 mL of 2-methoxyethanol, and 14 uL of ethanolamine was added, and the mixture was stirred for 6 hours. The prepared solution was spin-coated at 4000 rpm onto a transparent rigid conductive substrate and / or a bottom electrode, and annealed at 200 ° C for 1 hour to obtain a ZnO electron transport layer;

[0093] S3. Preparation of interface layer:

[0094] 1 g PFN-Br was dissolved in 2 mL methanol and stirred for 6 h. The prepared solution was spin-coated onto the electron transport layer at 5000 rpm to obtain a PFN-Br interface layer.

[0095] S4. Preparation of active layer:

[0096] PM6:CH22 was dissolved in chloroform solvent at a mass ratio of 1:1, with a PM6 concentration of 6 mg / mL, at 40°C for 5 hours, and the prepared solution was spin-coated onto the PFN-Br interface layer at 2000 rpm and annealed at 100°C for 10 minutes to obtain a PM6:CH22 active layer;

[0097] S4. Preparation of hole transport layer:

[0098] A 5nm thick hole transport layer was evaporated on the photoactive layer;

[0099] S5. Evaporation of top electrode:

[0100] A 200nm thick top electrode Ag layer is evaporated on the hole transport layer to obtain an organic photodetector device.

[0101] Example 3 Preparation of organic photodetector PM6:CH23

[0102] S1. Transparent rigid conductive substrate and / or bottom electrode preparation:

[0103] The transparent rigid conductive substrate and / or the bottom electrode are ultrasonically cleaned with glass cleaning liquid, deionized water, acetone, and isopropanol in sequence, and then the surface of the transparent rigid conductive substrate and / or the bottom electrode is blown dry with a nitrogen gun, irradiated in a UV ozone treatment device for 15 minutes, and placed in a glass culture dish for standby use;

[0104] S2. Preparation of electron transport layer:

[0105] 0.05 g of zinc acetate was dissolved in 2 mL of 2-methoxyethanol, and 14 uL of ethanolamine was added, and the mixture was stirred for 6 hours. The prepared solution was spin-coated at 4000 rpm onto a transparent rigid conductive substrate and / or a bottom electrode, and annealed at 200 ° C for 1 hour to obtain a ZnO electron transport layer;

[0106] S3. Preparation of interface layer:

[0107] 1 g PFN-Br was dissolved in 2 mL methanol and stirred for 6 h. The prepared solution was spin-coated onto the electron transport layer at 5000 rpm to obtain a PFN-Br interface layer.

[0108] S4. Preparation of active layer:

[0109] PM6:CH23 was dissolved in chloroform solvent at a mass ratio of 1:1, with a PM6 concentration of 6 mg / mL, at 40°C for 5 hours, and the prepared solution was spin-coated onto the PFN-Br interface layer at 2000 rpm and annealed at 100°C for 10 minutes to obtain a PM6:CH23 active layer;

[0110] S4. Preparation of hole transport layer:

[0111] A 5nm thick hole transport layer was evaporated on the photoactive layer;

[0112] S5. Evaporation of top electrode:

[0113] A 200nm thick top electrode Ag layer is evaporated on the hole transport layer to obtain an organic photodetector device.

[0114] Example 4 Performance Test

[0115] At the same time, the purchased Si-2DU6 and Si-2CU84 photodetectors and the organic photodetectors prepared by Examples 1, 2, and 3 were subjected to EQE (external quantum efficiency) test, response calculation, dark current test, specific detection rate calculation, and response time test. The test results are as follows: Figure 6-10 And as shown in Table 1.

[0116] Table 1

[0117] Material Name <![CDATA[650nmt rise / t fall ]]> PM6:Y6 1.3 / 1.5μs PM6:CH22 1.2 / 1.6μs PM6:CH23 1.3 / 1.3μs Si-2DU6 7.6 / 11.5μs Si-2CU84 5.8 / 9.7μs

[0118] The test results of the commercial photodetector Si-2DU6 are that the dark current of the OPD is -170nA under a reverse bias of -1V; the dark current of the OPD is -26nA under a reverse bias of -0.1V; and the dark current of the OPD is -10pA under no bias. It exhibits good light absorption efficiency in the wavelength range of 310-1080nm. The maximum responsivity at 890nm is 0.62A / W, and the specific detection rate reaches 7.10×10 -13 Jones. The response to 650nm wavelength light is 0.42A / W, and the rise time is t rise and the fall time t fall 7.6 / 11.5μs respectively.

[0119] The test results of the commercial photodetector Si-2CU84 are that under -1V reverse bias, the dark current of OPD is -1.5nA; under -0.1V reverse bias, the dark current of OPD is -600pA; under no bias, the dark current of OPD is -1pA. It shows good light absorption efficiency in the wavelength range of 310-1080nm. The maximum responsivity at 900nm is 0.58A / W, and the specific detection rate reaches 6.67×10 -13 Jones. The response to 650nm wavelength light is 0.26A / W, and the rise time is t rise and the fall time t fall 5.8 / 9.7μs respectively.

[0120] The test results of the organic photodetector PM6:Y6 are that the dark current of OPD is -5nA under -1V reverse bias; the dark current of OPD is -80pA under -0.1V reverse bias; and the dark current of OPD is -10pA under no bias. It exhibits good light absorption efficiency in the wavelength range of 330-920nm. The maximum responsivity is 0.53A / W at 810nm, and the specific detection rate is 6.06×10-13 Jones. The response to 650nm wavelength light is 0.46A / W, and the rise time is t rise and the fall time t fall 1.3 / 1.5μs respectively.

[0121] The test results of the organic photodetector PM6:CH22 are that the dark current of OPD is -5.5nA under -1V reverse bias; the dark current of OPD is -530pA under -0.1V reverse bias; and the dark current of OPD is -17pA under no bias. It exhibits good light absorption efficiency in the wavelength range of 330-920nm. The maximum responsivity is 0.55A / W at 800nm, and the specific detection rate is 6.30×10 -13 Jones. The response to 650nm wavelength light is 0.39A / W, and the rise time is t rise and the fall time t fall 1.2 / 1.6μs respectively.

[0122] The test results of the organic photodetector PM6:CH23 are that under -1V reverse bias, the dark current of OPD is -13nA; under -0.1V reverse bias, the dark current of OPD is -1.6nA; under no bias, the dark current of OPD is -30pA. It exhibits good light absorption efficiency in the wavelength range of 330-920nm. The maximum responsivity at 790nm is 0.47A / W, and the specific detection rate reaches 5.38×10 -13 Jones. The response to 650nm wavelength light is 0.37A / W, and the rise time is t rise and the fall time t fall They are 1.3 / 1.3μs respectively.

[0123] Taking all factors into consideration, the liquid level detector requires that the photoelectric detector has a certain recognition ability for the liquid surface reflected light and circuit as well as the output photocurrent during use.

[0124] The minimum responsivity requirement of the photodetector is calculated by the following formula (i):

[0125] R=Iph / P (i)

[0126] Where R is the responsivity, Iph is the photocurrent, and P is the optical power.

[0127] From the above formula, it can be calculated that the responsivity of the photoelectric detector used as a liquid level detector at 620-660nm should be greater than 0.1A / W.

[0128] like Figure 7As shown, at 620-660 nm, the commercial photodetectors Si-2DU6, Si-2CU84 used in this embodiment and the organic photodetectors PM6:Y6, PM6:CH22 and PM6:CH23 prepared by Examples 1, 2 and 3 all meet the use requirements of the liquid level detector.

[0129] Example 5 Preparation of Photoelectric Liquid Level Detector

[0130] The photoelectric liquid level detector is connected to the light emitting diode drive circuit by using the PA4 IO port of the embedded processor; the light emitting diode drive circuit is connected to the light emitting diode through the Jled (2-pin single-row needle with a 2.54mm pitch) connector; the photoelectric detector is connected to the current-voltage conversion circuit through the Jsen (2-pin single-row needle with a 2.54mm pitch) connector; the voltage-current conversion circuit is connected to the ADC through the R16 resistor; the ADC is connected to the embedded processor through PA1, PA5, PA6, PA7, PA8, PA11, and PA12.

[0131] like Figure 3 The diagram shows the principle diagram of the LED driving circuit; Figure 4 The circuit diagram of the current-voltage conversion circuit is shown in FIG. Figure 5 Shown is the schematic diagram of the ADC interface circuit.

[0132] Example 6 Photoelectric Liquid Level Detector Calculation Method

[0133] like Figure 1 As shown, the photoelectric liquid level detector is used to determine the liquid level distance by measuring the intensity of the reflected light. The schematic diagram of the photoelectric liquid level detector circuit is shown in Figure 2 shown.

[0134] The first law of illumination describes that light attenuates with distance, and the light intensity is inversely proportional to the square of the distance between the object and the light source, as expressed by the following equation (1):

[0135] E=I / D 2 (1)

[0137] Where E is the illumination, D is the distance between the light source and the liquid surface, and I is the luminous intensity of the light source; this indicates that as the distance to the liquid level increases, the light intensity measured by the detector becomes weaker.

[0138] The liquid level test device based on the photoelectric liquid level detector measures the difference in output photocurrent under a wavelength of 640nm and in a dark environment, and calculates the distance from the liquid level to the measuring device by the following formula (2):

[0139] L = a*(I light -I dark )-b (2)

[0141] The parameters a and b are obtained by fitting the measured data. light is the output photocurrent at 640nm wavelength, I dark To output photocurrent in a dark environment.

[0142] Example 7 Photoelectric Liquid Level Detector Performance Test

[0143] The performance of the photoelectric liquid level detector prepared in Example 5 was tested, and the test results are shown in Table 2:

[0144] Table 2

[0145]

[0146] Combination Fig.11 It can be seen that both the organic photodetector and the commercial silicon-based photodetector prepared in the embodiment show excellent liquid level detection performance in the liquid level detection device.

[0147] Combined with the data analysis in Table 2, there is an excellent linear relationship between the output current of the photodetector and the liquid level (i.e., the distance from the detector to the liquid surface). As the liquid level drops, the circuit output current also drops. This shows that when the two photodetectors are used in the liquid level detector for liquid level detection, they both have good stability and can respond quickly, which effectively improves the accuracy of liquid level detection and realizes non-contact and accurate detection of the liquid level.

[0148] From the specific data analysis, it can be seen that at the same liquid level (the distance from the detector to the measured liquid surface), the output current of the organic photodetector PM6:Y6 is significantly greater than the output current of other photodetectors, making it easier for the circuit to recognize the signal of the organic photodetector PM6:Y6 than the signals of other photodetectors. In contrast, the organic photodetector PM6:Y6 can more effectively improve the measurement accuracy of the liquid level detector and has a better use effect.

[0149] The above is only a preferred embodiment of the present invention. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A liquid level detector based on photoelectric detection, characterized in that: include: A light emitting diode emits light waves to the water surface being measured; A light emitting diode dimming chip, used to control the working parameters of the light emitting diode; Photoelectric detector, used to receive light waves reflected from the water surface and convert the received light waves into electrical signals; A 24-bit high-precision ADC receives the electrical signal and performs analog-to-digital conversion; An embedded processor receives the digital signal after analog-to-digital conversion and calculates the water level based on the digital signal; Wherein, the photodetector is a silicon-based photodetector or an organic photodetector.

2. A liquid level detector based on photoelectric detection as claimed in claim 1, characterized in that: The photodetector is an organic photodetector, comprising a transparent rigid conductive substrate and / or a bottom electrode, an electron transport layer, a modification layer, a photoactive layer, a hole transport layer and a top electrode arranged from bottom to top; or a transparent rigid conductive substrate and / or a bottom electrode, a hole transport layer, a photoactive layer, an electron transport layer and a top electrode arranged from bottom to top; The photoactive layer is a film formed by blending a polymer donor and an organic acceptor; the polymer donor includes but is not limited to at least one of P3HT, PBDB-T, PM6, and PCE-10; the organic acceptor includes but is not limited to at least one of ITIC, IHIC, Y6, Y6-D, CH17, IEICO-4F, COTIC-4F, PDTTIC-4F, CH22, and CH23.

3. A liquid level detector based on photoelectric detection as claimed in claim 2, characterized in that: The polymer donor is PM6, and the organic acceptor is at least one of Y6, CH22, and CH23.

4. A liquid level detector based on photoelectric detection as claimed in claim 3, characterized in that: The polymer donor is PM6, and the organic acceptor is Y6.

5. A liquid level detector based on photoelectric detection as claimed in claim 2, characterized in that: The mass ratio of the polymer donor to the organic acceptor is 1:1-1:

100.

6. A liquid level detector based on photoelectric detection as claimed in claim 5, characterized in that: The mass ratio of the polymer donor to the organic acceptor is 1:

1.

7. A liquid level detector based on photoelectric detection as claimed in claim 2, characterized in that: The photoactive layer has a thickness of 10 nm to 200 nm.

8. A liquid level detector based on photoelectric detection as claimed in claim 2, characterized in that: The transparent rigid conductive substrate includes but is not limited to at least one of ITO, FTO, AZO, GZO conductive glass, metal nanowire substrate and highly transparent metal film substrate; The bottom electrode includes but is not limited to at least one of indium tin oxide, metal nanowires, carbon nanotubes, conductive polymers, metal grids, and graphene; The top electrode includes but is not limited to at least one of silver, gold, lithium, calcium, strontium, barium, indium, magnesium, aluminum, and copper; the electron transport layer is at least one of ZnO nanoparticles, ZnO nanocrystals, TiO2, SnO2, WO3, and PDINO; The hole transport layer includes but is not limited to MoO3, PEDOT:PSS, CuO x 、WO3、NiO x , SAM-2PACz; The modification layer includes but is not limited to at least one of PFN-Br, PEIE, and PFN / PFBT.

9. A liquid level detector based on photoelectric detection as claimed in claim 1, characterized in that: The embedded processor is connected to the light-emitting diode drive circuit through the PA4 IO port, the light-emitting diode drive circuit is connected to the light-emitting diode through the Jled connector, the photodetector is connected to the current-voltage conversion circuit through the Jsen connector, and the voltage-current conversion circuit is connected to the ADC through the R16 resistor; the ADC is connected to the embedded processor through PA1, PA5, PA6, PA7, PA8, PA11, and PA12.

10. A method for preparing a liquid level detector based on photoelectric detection according to any one of claims 2 to 8, characterized in that: S1. Preparation of transparent rigid conductive substrate and / or bottom electrode: Ultrasonic cleaning of the transparent rigid conductive substrate and / or the bottom electrode is performed in sequence using glass cleaning liquid, deionized water, acetone, and isopropanol, and then the surface of the transparent rigid conductive substrate and / or the bottom electrode is dried using a nitrogen gun, and then irradiated in an ultraviolet ozone treatment device and placed in a glass culture dish for standby use; S2. Preparation of electron transport layer: Dissolving zinc acetate in 2-methoxyethanol, adding ethanolamine, spin-coating the prepared solution onto a transparent rigid conductive substrate and / or a bottom electrode, and performing annealing to obtain a ZnO electron transport layer; S3. Preparation of interface layer: Dissolve PFN-Br in methanol, and spin-coat the prepared solution onto the electron transport layer to obtain a PFN-Br interface layer; S4. Preparation of active layer: The polymer donor and the organic acceptor are dissolved in chloroform solvent, and the prepared solution is spin-coated on the PFN-Br interface layer and annealed to obtain a photoactive layer; S4. Preparation of hole transport layer: Vapor depositing a hole transport layer on the photoactive layer; S5. Evaporation of top electrode: Vapor-depositing a top electrode Ag on the hole transport layer to obtain an organic photodetector device; S6. Organic photoelectric liquid level detector circuit assembly.

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