A measurement system and method for the photoconductivity properties of perovskite based on RC circuits

Abstract

This invention relates to the field of measuring the electrical conductivity properties of photosensitive materials, and particularly to a measurement system and method for the photoconductivity properties of perovskite based on an RC circuit. The measurement system includes a measurement circuit, an adjustable constant voltage power supply, a dark chamber, a voltmeter, and a light source. The resistor to be measured and the light source are located in the dark chamber, with the adjustable constant voltage power supply connected to the light source. The voltmeter is connected to the light source. The measurement circuit connects the resistor to be measured to the circuit via wires. The measurement circuit includes a protective resistor, a capacitor, a power supply, a first voltage comparator, a second voltage comparator, a first voltage divider resistor, a second voltage divider resistor, a third voltage divider resistor, an RS flip-flop, a transistor, a microcontroller, and a display. This invention proposes a nonlinear fitting analysis method that is not linearizable, representing the deviation between experimental data and the fitted curve as the square of the ratio of their difference to the average value. This avoids the problem that the error range increases with the resistance data when measuring variable resistors with large change rates.

Description

Technical Field

[0001] This invention relates to the field of measuring the electrical conductivity properties of photosensitive materials, and particularly to a system and method for measuring the photoconductivity properties of perovskite based on an RC circuit. Background Technology

[0002] In experimental research in disciplines such as physics and electronic engineering, accurate resistance measurement is a crucial fundamental aspect. The resistance of some conductors changes with the external environment; therefore, real-time monitoring of these resistance changes provides a digital representation of these environmental variations. Such conductors have found widespread applications, such as photoresistors in hallway motion-activated lighting control circuits, thermistors in temperature sensors, and gas-sensitive resistors in gas sensors. Methylamine iodide-based perovskite, as a novel photosensitive material, has a response wavelength range of approximately [missing information]. Compared to other materials, it has a wider resistivity range, making it a high-performance photosensitive material. The resistivity variation range of methylamine iodide-based perovskite is too large; rough measurements show its variation range to be... Traditional measurement methods struggle to achieve accurate measurements across the entire resistance range. Previously, the measurement of photoresistors primarily relied on instruments such as bridges, multimeters, and dedicated impedance analyzers. While widely used in various scenarios, these instruments still have significant limitations. For example, the four-wire bridge method, although providing high precision, is insufficient for the range and accuracy requirements of large resistance measurements. Furthermore, measuring devices like multimeters generally have input impedance, which significantly impacts the accuracy of high-resistance measurements; the larger the resistance value, the greater the error range when measuring variable resistors with large resistance changes. This invention aims to design a novel resistance measurement device and method that meets the requirements for accurate measurement of large resistances while also offering advantages such as low cost and ease of operation. It further explores the relationship between the resistance and surface illuminance of methylamine iodide-based perovskite photosensitive materials, predicting the relationship between resistance and surface illuminance beyond the measured values. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention provides a measurement system and method for the photoconductivity characteristics of perovskite based on an RC circuit. The measurement system includes a measurement circuit, an adjustable constant voltage power supply, a dark chamber, a voltmeter, and a light source. The resistor to be measured and the light source are located in the dark chamber, with the resistor to be measured positioned at the center of the light source's illumination. The adjustable constant voltage power supply is connected to the light source. The voltmeter is connected to the light source to measure its voltage. The measurement circuit connects the resistor to be measured to the circuit via wires. The measurement circuit includes a protective resistor, a capacitor, a power supply, a first voltage comparator, a second voltage comparator, a first voltage divider resistor, a second voltage divider resistor, a third voltage divider resistor, an RS flip-flop, a transistor, a microcontroller, and a display. The resistor to be measured, the protective resistor, and the capacitor are connected in series with the power supply. A first point between the protective resistor and the capacitor is simultaneously connected to the positive input terminal of the first voltage comparator and the inverting input terminal of the second voltage comparator for voltage comparison. The first voltage divider resistor, the second voltage divider resistor, and the third voltage divider resistor... A resistor is connected in series with the power supply to divide the power supply voltage, and is connected in parallel with the resistor under test, protection resistor, and capacitor circuit. The first, second, and third voltage divider resistors have the same resistance value. The second point of the 2 / 3 voltage value between the first and second voltage divider resistors is connected to the inverting input of the first voltage comparator, and the third point of the 1 / 3 voltage value between the second and third voltage divider resistors is connected to the non-inverting input of the second voltage comparator. The outputs of the first and second voltage comparators are respectively connected to the reset and set ports of an RS flip-flop composed of two NAND gates. The output of the RS flip-flop serves as the final output value OUT of the circuit and is connected to the base of a transistor to control the transistor's on / off state. One end of the capacitor is grounded, and the other end is connected to the collector of the transistor through the protection resistor, allowing it to charge and discharge under the control of the transistor's on / off state. The output of the RS flip-flop is also connected to a microcontroller, which reads the path (charging) time. Discharge time The monitor is connected to the microcontroller.

[0004] The process of measuring the resistance value of the resistor under test within the microcontroller is as follows:

[0005] The voltage comparator controls the connection of the transistor by comparing the voltages at the first, second, and third points.

[0006] When the voltage is lower At this time, the transistor is open-circuited, and the capacitor is charged;

[0007] When the voltage is At this time, the circuit remains open and continues to charge;

[0008] When the voltage is higher At this time, the transistor is in the circuit and the capacitor is discharging;

[0009] When the voltage is At this time, the circuit remains open and continues to discharge;

[0010] The microcontroller reads the charging time output from the fourth bit of the RS flip-flop. Discharge time ;

[0011] During charging, the upper limit of the capacitor voltage is taken as... The lower limit is ,calculate:

[0012] (1)

[0013] in, The power supply voltage, The current flowing through the loop. The resistance value of the resistor to be measured To protect the resistance value, To accumulate charge in the capacitor, The charging time for the capacitor. C is the capacitor discharge time; C is the capacitance value. It is the natural logarithm to the base e;

[0014] During the discharge process Isolation, computation:

[0015] (2)

[0016] By combining equations (1) and (2), calculate the final expression:

[0017] (3)

[0018] The microcontroller continuously reads several resistance values, calculates the average value, and outputs the final resistance value.

[0019] This invention provides a method for measuring the photoconductivity of perovskite based on an RC circuit, using the aforementioned measurement system, comprising the following steps:

[0020] (1) Determine the relationship between the illuminance of the light source and the voltage of the adjustable constant voltage power supply;

[0021] (2) Open the dark chamber, place the resistor to be measured (i.e., the perovskite material) into the dark chamber, with the resistor to be measured located at the center of the light source, and connect the resistor to the measuring circuit through a wire; close the dark chamber.

[0022] (3) Adjust the output voltage of the adjustable constant voltage power supply to control the brightness of the light source output corresponding illuminance, read the voltmeter reading and the resistance measurement value displayed by the measuring circuit and record it;

[0023] (4) Change to a different color light source and repeat the above steps;

[0024] (5) By combining the obtained data, the illuminance-resistance relationship data is obtained;

[0025] Theoretical derivation yields the following relationship between resistance and illuminance on the upper surface of the photosensitive material when the material is almost opaque. for:

[0026]

[0027] Where R is the theoretical resistance of the resistor to be measured; , respectively, represent the length, width, and thickness of the resistor to be measured; e represents the elementary charge; These represent the electron mobility and hole mobility of the photosensitive material, respectively. Quantum efficiency of photogenerated carriers; The wavelength of the incident light; denoted as illuminance on the upper surface of the photosensitive material; h is Planck's constant; c is the speed of light in air. This is the low-light apparent efficiency function (its value can be obtained from a table given the wavelength); It is a constant, and for light of any wavelength, .

[0028] set up (in Material parameters are all consistent with (related to), then the above formula can be written as:

[0029]

[0030] in, These are the parameters that need to be fitted for each color of light when performing nonlinear curve fitting on the data.

[0031] The beneficial effects of this invention are:

[0032] This invention achieves digital dynamic measurement display, effectively replacing the complex circuits of traditional measuring instruments; it realizes intelligent measurement, that is, by analyzing and controlling the data display, it obtains highly accurate R and C measurement data; the measurement method provided by this invention has a large measurement range, and the precise measurement range can be adjusted by changing the size of the protective resistor and capacitor; this invention innovatively proposes a nonlinear fitting analysis method that is not linearizable, that is, the deviation between experimental data and the fitted curve is represented by the square of the ratio of the difference between the two to the average value. When this value is minimized, the fitted curve is closest to the data point. This method can balance the weight of each data point and avoid the problem that the larger the resistance data, the larger the error range when measuring variable resistors with large change ratios. Thus, the curve obtained by this invention fits well at all points, and there will be no phenomenon of complete separation due to excessive error in a certain segment. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the overall structure of the measurement system of the present invention;

[0034] Figure 2 This is a schematic diagram of the measurement circuit structure of the present invention;

[0035] Figure 3 A circuit diagram illustrating the introduction of a protective resistor in this invention;

[0036] Figure 4 This is a circuit diagram illustrating the isolation of the resistor under test according to the present invention;

[0037] Figure 5 This is a schematic diagram of the capacitor voltage changing over time according to the present invention;

[0038] Figure 6 This is a schematic diagram of the voltage change over time at the detection terminal of the present invention.

[0039] Figure 7 This is a schematic diagram of a simulation of methylamine iodide-based perovskite material according to an embodiment of the present invention;

[0040] Figure 8 This is a schematic diagram illustrating the change in electrical resistance with illuminance under white light illumination according to an embodiment of the present invention;

[0041] Figure 9 This is a schematic diagram illustrating the change in resistance with illuminance under red light irradiation according to an embodiment of the present invention;

[0042] Figure 10 This is a schematic diagram illustrating the change in electrical resistance with illuminance under green light irradiation according to an embodiment of the present invention;

[0043] Figure 11 This is a schematic diagram illustrating the change in electrical resistance with illuminance under ultraviolet light irradiation according to an embodiment of the present invention;

[0044] Figure 12 This is a schematic diagram comparing the change in resistance with illuminance under different colors of light in an embodiment of the present invention.

[0045] 1. Measuring circuit; 2. Adjustable constant voltage power supply; 3. Dark room; 4. Voltmeter; 5. Resistor to be measured; 6. Protective resistor; 7. Capacitor; 8. Power supply; 9. First voltage comparator; 10. Second voltage comparator; 11. First voltage divider resistor; 12. Second voltage divider resistor; 13. Third voltage divider resistor; 14. RS flip-flop; 15. Transistor; 16. First position; 17. Second position; 18. Third position; 19. Fourth position. Detailed Implementation

[0046] like Figure 1As shown in the figure, this embodiment provides a measurement system and method for the photoconductivity characteristics of perovskite based on RC circuit. The measurement system includes a measurement circuit 1, an adjustable constant voltage power supply 2, a dark chamber 3, a voltmeter 4, and a light source.

[0047] The resistor to be tested 5 (in this embodiment, it is a methylamine iodide-based perovskite material) and the light source (in this embodiment, an LED lamp bead) are placed in the dark chamber 3. The dark chamber 3 is equipped with a clamping and fixing device for the resistor to be tested 5, and the resistor to be tested 5 is located at the center of the light source. The adjustable constant voltage power supply 2 is connected to the light source. The voltmeter 4 is connected to the light source to measure the voltage of the light source. The measuring circuit 1 connects the resistor to be tested 5 to the circuit through wires.

[0048] like Figure 2 As shown, the measurement circuit 1 includes a protective resistor 6, a capacitor 7, a power supply 8, a first voltage comparator 9, a second voltage comparator 10, a first voltage divider resistor 11, a second voltage divider resistor 12, a third voltage divider resistor 13, an RS flip-flop 14, a transistor 15, a microcontroller, and a display. The resistor under test 5, the protective resistor 6, and the capacitor 7 are connected in series with the power supply 8. The first point 16 between the protective resistor 6 and the capacitor 7 is simultaneously connected to the positive input terminal of the first voltage comparator 9 and the negative input terminal of the second voltage comparator 10 for voltage comparison. The first voltage comparator 9, the second voltage comparator 10, and the RS flip-flop 14 constitute a comparison controller. The first voltage divider resistor 11, the second voltage divider resistor 12, and the third voltage divider resistor 13 are connected in series with the power supply 8 to divide the voltage of the power supply 8, and are connected in parallel with the circuit of the resistor under test 5, the protective resistor 6, and the capacitor 7. The first voltage divider resistor 11, the second voltage divider resistor 12, and the third voltage divider resistor 13 are connected in series with the power supply 8 to divide the voltage of the power supply 8, and are connected in parallel with the circuit of the resistor under test 5, the protective resistor 6, and the capacitor 7. The voltage divider resistors 13 have the same resistance value. The second point 17, representing 2 / 3 of the voltage between the first voltage divider resistor 11 and the second voltage divider resistor 12, is connected to the inverting input of the first voltage comparator 9. The third point 18, representing 1 / 3 of the voltage between the second voltage divider resistor 12 and the third voltage divider resistor 13, is connected to the non-inverting input of the second voltage comparator 10. The outputs of the first voltage comparator 9 and the second voltage comparator 10 are respectively connected to the reset and set ports of the RS flip-flop 14, which is composed of two NAND gates. The output of the RS flip-flop 14 serves as the final output value OUT of the circuit and is connected to the base of the transistor 15, controlling the switching on and off of the transistor 15. One end of the capacitor 7 is grounded, and the other end is connected to the collector of the transistor 15 through the protection resistor 6, charging and discharging under the control of the switching on and off of the transistor 15. The output of the RS flip-flop 14 is also connected to the microcontroller, which reads the path (charging) time. Discharge time The display is connected to the microcontroller. In this embodiment, the resistor to be tested 5 (methylamine iodide-based perovskite material) has a length of 5.01 mm, a width of 5.46 mm, and a resistance of R1; the distance from the LED head to the surface of the resistor to be tested 5 is 40.63 mm; the protection resistor 6 has a resistance of R2 = 2 MΩ; the capacitor 7 has a value of C = 10 nF; the power supply 8 has a voltage of U0 = 5 V; and the first voltage divider resistor 11, the second voltage divider resistor 12, and the third voltage divider resistor 13 have the same resistance value of R0.

[0049] To prevent excessive variation in the resistance R1 of the resistor under test 5 from damaging the circuit, a protective resistor 6 is introduced during charging to reduce the rate of change in circuit resistance. Figure 3 Red wire circuit;

[0050] The upper limit of the voltage of capacitor 7 is set as follows: The lower limit is Therefore, we have:

[0051] (1)

[0052] Where U0 is the voltage of the power supply 8, i is the current through the circuit, R1 is the resistance of the resistor under test 5, R2 is the resistance of the protection resistor 6, q is the amount of charge accumulated in capacitor 7, C is the capacitance of capacitor 7, t1 is the charging time of capacitor 7, t2 is the discharging time of capacitor 7; C is the capacitance value. It is the natural logarithm to the base e;

[0053] Isolating R1 during the discharge process yields... Figure 4 The red-wire circuit; therefore, we have:

[0054] (2)

[0055] By combining equations (1) and (2), we can obtain the final expression:

[0056] (3)

[0057] It is necessary to monitor the voltage across capacitor 7 and control the circuit connection.

[0058] The voltage is obtained by connecting three voltage divider resistors in series. The second point is 17, and the third point is 18;

[0059] A voltage comparator is introduced to control the connection of transistor 15, enabling it to... Figure 3 and Figure 4 The switching is achieved by comparing the voltages at the first point 16, the second point 17, and the third point 18 to control the connection of transistor 15. The output terminal of RS flip-flop 14, at the fourth point 19, is connected to the microcontroller to read the path (charging) time. Discharge time By combining the capacitance 7 and the final expression (3), the value of the resistor 5 to be measured can be obtained.

[0060] The curves showing the changes in voltage across capacitor 7 and voltage at the detection terminal over time during circuit operation are as follows: Figure 5 , 6 As shown;

[0061] When the voltage is lower At that time, it forms like Figure 3 In the circuit shown by the red line, transistor 15 is open-circuited and capacitor 7 is charged.

[0062] When the voltage is At this time, the circuit remains open and continues to charge.

[0063] When the voltage is higher At that time, it forms like Figure 4 The circuit shown by the red line has transistor 15 in the circuit and capacitor 7 discharging.

[0064] When the voltage is At this time, the circuit remains open and continues to discharge.

[0065] Because the comparator controller responds very quickly, it can be directly considered that the voltage across capacitor 7 is... It is repeatedly charged and discharged.

[0066] The comparator controller primarily consists of two voltage comparators and two AND / OR gates. In a typical application, the two voltage comparators monitor the voltage of the external capacitor 7. They generate a square wave in oscillator mode, the frequency of which depends on the RC circuit connected to it. By measuring this frequency, the value of the resistance or capacitance 7 in the circuit can be deduced.

[0067] The square wave generated at the output port is used by an STM32 microcontroller to act on a timer in capture mode. This allows the STM32 microcontroller to calculate the frequency and duty cycle of the generated square wave, and then calculate the resistance value: it continuously reads 20 resistance values ​​and calculates the average as the final resistance value. The calculation results are displayed on an LCD1602 screen, and can also be uploaded to a computer and saved as an Excel spreadsheet via serial port.

[0068] This invention provides a method for measuring the photoconductivity of perovskite based on an RC circuit, using the aforementioned measurement system, comprising the following steps:

[0069] (1) Determine the relationship between the illuminance of the light source and the voltage of the adjustable constant voltage power supply 2; adjust the power supply voltage to control the illuminance of the LED beads, and make a coarse adjustment to observe the change in resistance with the brightness of each color of LED beads;

[0070] Based on the observed changes, select appropriate illuminance sampling points, record the voltage of the lamp beads at this illuminance, and obtain illuminance-voltage relationship data;

[0071] (2) Open the dark chamber 3, place the resistor to be measured 5 (i.e., perovskite material) into the dark chamber 3, and connect the resistor to be measured 5 to the measuring circuit 1 through the wire; close the dark chamber 3;

[0072] (3) Adjust the output voltage of the adjustable constant voltage power supply 2 to control the corresponding brightness of the light source output, accurately measure the photoresistance value under the corresponding voltage, read the reading of voltmeter 4 and the measured resistance value displayed by the measuring circuit 1 and record it; obtain the resistance-voltage relationship data.

[0073] (4) Repeat the above steps using different colored light sources; use white light (mixed light) and red light respectively. ), green light ( ), Purple Light ( LED beads are used to irradiate photosensitive materials;

[0074] (5) Combine the obtained data to obtain the illuminance-resistance relationship data.

[0075] In order to predict the relationship between resistance and surface illuminance beyond the measured values, this embodiment derives the formula for their relationship.

[0076] Establish theoretical models, such as Figure 7 As shown;

[0077] To simplify the calculation, we assume that the material is a pure, impurity-free intrinsic semiconductor, i.e., the electron concentration is... With hole concentration equal:

[0078] (4)

[0079] In a dark environment (because the resistor under test is a photoresistor, the experiment must be conducted in a dark environment), the incident light power density for:

[0080] (5)

[0081] in, This is the low-light apparent efficiency function (its value can be obtained from a table if the wavelength is known). The illuminance of the material in the z-direction:

[0082] (6)

[0083] in, The light absorption coefficient of the material. Illuminance on the upper surface of the photosensitive material;

[0084] Incident photon flux density for:

[0085] (7)

[0086] Where h is Planck's constant, These are the frequency and speed of light in air, respectively.

[0087] Photogenerated carrier generation rate for:

[0088] (8)

[0089] in, Quantum efficiency of photogenerated carriers;

[0090] The average photogenerated carrier generation rate for:

[0091] (9)

[0092] Photogenerated carrier recombination rate for:

[0093] (10)

[0094] For light of any wavelength, It is a constant, and ;

[0095] At steady state, the generation rate equals the recombination rate, that is:

[0096] (11)

[0097] Joint And because the material is almost opaque, that is We can obtain:

[0098] (12)

[0099] And from conductivity (13)

[0100] (14)

[0101] Where S is the cross-sectional area of ​​the resistor to be measured;

[0102] The final relationship between resistance and surface illuminance can be obtained as follows:

[0103] (15)

[0104] Where R is the theoretical resistance of the resistor to be measured; , respectively, represent the length, width, and thickness of the resistor to be measured; e represents the elementary charge; These represent the electron mobility and hole mobility of the photosensitive material, respectively. Quantum efficiency of photogenerated carriers; The wavelength of the incident light; denoted as illuminance on the upper surface of the photosensitive material; h is Planck's constant; c is the speed of light in air. This is the low-light visual efficiency function.

[0105] The data measured using the above measurement method are shown in Table 1-4 below:

[0106] Table 1. Measurement data of voltage-resistance-illuminance under white light irradiation.

[0107]

[0108] Table 2. Measurement data of voltage-resistance-illuminance under red light irradiation.

[0109]

[0110] Table 3. Measurement data of voltage-resistance-illuminance under green light irradiation.

[0111]

[0112] Table 4. Measurement data of voltage-resistance-illuminance under ultraviolet light irradiation.

[0113]

[0114] Nonlinear curve fitting was performed on the data using Origin software.

[0115] In nonlinear regression, when performing nonlinear curve fitting on data, the parameters that need to be fitted for each color of light are... The confidence interval is calculated based on nonlinear least squares estimation:

[0116]

[0117] in, This represents the random error between the actual observed values ​​and the theoretical model predictions in a nonlinear regression model.

[0118] By minimizing the sum of squared residuals ( Estimate parameters.

[0119] Parameter estimates The covariance matrix is:

[0120]

[0121] in It is a Jacobian matrix. ; It is the error variance, derived from the mean square error ( )estimate:

[0122]

[0123] In the formula, N represents the amount of data. The number of parameters.

[0124] The standard error of the parameters is the square root of the diagonal elements of the covariance matrix:

[0125]

[0126] Based on the t-distribution (since the error variance is unknown), the confidence interval is:

[0127]

[0128] In summary, regarding the parameters Its 95% confidence interval is:

[0129]

[0130] Substitute the data from each group to obtain the uncertainty. as follows:

[0131] Table 5 Data table

[0132]

[0133] Furthermore, based on the minimum scale division values ​​of the vernier caliper and lux meter used in the experiment, we have:

[0134]

[0135]

[0136]

[0137]

[0138] in, Let the standard uncertainties be the material length, width, thickness, and illuminance on the upper surface, respectively. Then, at a confidence probability of 0.95, the expanded uncertainty of the resistance is... for:

[0139]

[0140] Therefore, the final experimental results of the resistor can be obtained. for:

[0141]

[0142] The experimental images show that within the visible light range, for different wavelengths of light, when the illuminance is not high (less than...),... When the wavelength is long enough, the resistance of the photosensitive material changes significantly with the illuminance, and the change is more obvious with the longer the wavelength, which means that the material has excellent photosensitive properties.

Claims

1. A measurement system for the photoconductivity properties of perovskite based on an RC circuit, characterized in that: The system includes a measuring circuit, an adjustable constant voltage power supply, a darkroom, a voltmeter, and a light source. The resistor under test and the light source are located in the darkroom, with the resistor under test positioned at the center of the light source's illumination. The adjustable constant voltage power supply is connected to the light source. The voltmeter is also connected to the light source. The measuring circuit connects the resistor under test to the circuit via wires. The measuring circuit includes a protective resistor, a capacitor, a power supply, a first voltage comparator, a second voltage comparator, a first voltage divider resistor, a second voltage divider resistor, a third voltage divider resistor, an RS flip-flop, a transistor, a microcontroller, and a display. The resistor under test, the protective resistor, and the capacitor are connected in series with the power supply. The first point between the protective resistor and the capacitor is simultaneously connected to the positive input of the first voltage comparator and the negative input of the second voltage comparator for voltage comparison. The first voltage divider resistor, the second voltage divider resistor, and the third voltage divider resistor are connected in series with the power supply to divide the power supply voltage and are connected in parallel with the circuit containing the resistor under test, the protective resistor, and the capacitor. The first, second, and third voltage divider resistors have the same resistance value. Two-thirds of the voltage between the first and second voltage divider resistors is connected to the inverting input of the first voltage comparator at point two, and one-third of the voltage between the second and third voltage divider resistors is connected to the non-inverting input of the second voltage comparator at point three. The outputs of the first and second voltage comparators are connected to the reset and set ports of an RS flip-flop composed of two NAND gates, respectively. The output of the RS flip-flop serves as the final output value OUT of the circuit and is connected to the base of a transistor, controlling its on / off state. One end of a capacitor is grounded, and the other end is connected to the collector of the transistor through a protective resistor, allowing it to charge and discharge under the transistor's on / off control. The output of the RS flip-flop is also connected to a microcontroller, which reads the charging and discharging times. The display is connected to the microcontroller. The process of measuring the resistance value of the resistor under test within the microcontroller is as follows: The voltage comparator controls the connection of the transistor by comparing the voltages at the first, second, and third points. When the voltage is lower At this time, the transistor is open-circuited, and the capacitor is charged; When the voltage is At this time, the circuit remains open and continues to charge; When the voltage is higher At this time, the transistor is in the circuit and the capacitor is discharging; When the voltage is At this time, the circuit remains open and continues to discharge; The microcontroller reads the charging time output from the fourth bit of the RS flip-flop. Discharge time ; During charging, the upper limit of the capacitor voltage is taken as... The lower limit is ,calculate: （1） Where U0 is the power supply voltage, i is the current through the loop, R1 is the resistance value of the resistor to be measured, R2 is the resistance value of the protection resistor, q is the amount of charge accumulated in the capacitor, C is the capacitance value, t1 is the capacitor charging time, and t2 is the capacitor discharging time. This is the capacitance value. It is the natural logarithm to the base e; Isolate R1 during the discharge process and calculate: （2） By combining equations (1) and (2), calculate the final expression: （3） The microcontroller continuously reads several resistance values, calculates the average value, and outputs the final resistance value to be measured.

2. A method for measuring the photoconductivity of perovskite based on an RC circuit, characterized in that, The measurement and calculation of the photoconductivity properties of perovskite based on RC circuits as described in claim 1 includes the following steps: (1) Determine the relationship between the illuminance of the light source and the voltage of the adjustable constant voltage power supply; (2) Open the dark chamber, place the resistor to be measured (i.e., the perovskite material) into the dark chamber, with the resistor to be measured located at the center of the light source, and connect the resistor to the measuring circuit through a wire; close the dark chamber. (3) Adjust the output voltage of the adjustable constant voltage power supply to control the brightness of the light source output corresponding illuminance, read the voltmeter reading and the resistance measurement value displayed by the measuring circuit and record it; (4) Change to a different color light source and repeat the above steps; (5) By combining the obtained data, the illuminance-resistance relationship data is obtained; Theoretical formula for the relationship between resistance and illuminance on the upper surface of photosensitive material is derived. for: in, This is the theoretical resistance value of the resistor to be measured; These are the length, width, and thickness of the resistor to be measured, respectively. It is the elementary charge; These represent the electron mobility and hole mobility of the photosensitive material, respectively. Quantum efficiency of photogenerated carriers; The wavelength of the incident light; Illuminance on the upper surface of the photosensitive material; It is Planck's constant; The speed at which light travels through the air; Let be the low-light apparent efficiency function; It is a constant, and for light of any wavelength, ; set up ,but: These are the parameters that need to be fitted for each color of light when performing nonlinear curve fitting on the data.

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