Solid photo-thermal conversion efficiency measuring method and device based on photoelectric equivalence principle

Abstract

The invention discloses a solid photo-thermal conversion efficiency measuring method and device based on a photoelectric equivalence principle. According to the invention, the photoelectric equivalence principle is utilized, and the heat dissipation property of the solid sample is investigated by simulating the temperature change under the light heating condition through electric heating; the method comprises the following specific steps: firstly, measuring the temperature evolution of a sample in an electric heating process, deriving a heat dissipation coefficient by performing linear fitting during heat balance, then measuring the temperature evolution of the sample in a photo-thermal process under the irradiation of a light source, and further obtaining the accurate photo-thermal conversion efficiency of the sample through a heat balance equation. The method is wide in applicability and suitable for measuring the photo-thermal conversion efficiency of solid samples such as inorganic nanocrystals and organic materials.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photothermal measurement, in particular to a solid photothermal conversion efficiency measurement method and device based on the photoelectric equivalent principle. BACKGROUND

[0002] With the continuous development of new energy technology, photothermal conversion materials have shown great application potential in the fields of solar energy utilization, photothermal therapy, etc. However, how to accurately and efficiently measure the photothermal conversion efficiency of solid materials has always been a difficulty and focus of research in this field. Traditional measurement methods often have problems such as complex operation, low precision, low efficiency, etc., and are difficult to meet the needs of modern scientific research and industrial production. For example, the Roper model limits the sample to be measured in a vacuum state, the Richardson model is only suitable for testing the photothermal efficiency of liquid samples, the Wang model requires the sample to be placed in a solution for stirring, and the Pasciak model also requires the sample to be converted into a colloid or liquid for measurement. Therefore, the traditional method mainly simulates the solar heating process through experiments, and has a high dependence on liquid or colloidal nanoparticle solutions, which is usually limited by the overestimation of the measurement system quality item and the inaccuracy of the thermal dissipation coefficient fitting.

[0003] Since photothermal conversion is widely studied in potential applications including photothermal therapy and solar energy collection, accurate measurement of photothermal conversion efficiency is essential for the development of advanced materials for photothermal applications. Based on this, a new method for measuring photothermal conversion efficiency of solids is urgently needed. SUMMARY

[0004] In view of the above deficiencies of the prior art, the purpose of the present application is to provide a solid photothermal conversion efficiency measurement method and device based on the photoelectric equivalent principle. According to the photoelectric equivalent principle, the present application measures the photothermal conversion efficiency of solid materials by simulating the solar heating process through an electrical heating process, which can accurately and efficiently measure the efficiency of thermal energy conversion of solid materials under light conditions. The present application is suitable for measuring solid samples without phase change, and can be widely applied to the testing of inorganic and organic optoelectronic materials, overcoming the limitation of traditional methods that can only test solutions and colloids, and improving the problem that the traditional method easily overestimates the thermal dissipation coefficient, resulting in a large deviation of the actual efficiency. The present application can provide important technical support for the research, development and application of photothermal materials.

[0005] The technical solution of the present application is specifically introduced as follows.

[0006] The present application provides a solid photothermal conversion efficiency measurement method based on the photoelectric equivalent principle, which utilizes the photoelectric equivalent principle to simulate the temperature change under light heating conditions through electrical heating to investigate the thermal dissipation properties of solid samples. The specific steps are as follows:

[0007] (1) the solid sample is heated by a resistance sheet in a pure resistance circuit close to the solid sample, the temperature change of the solid sample when reaching thermal equilibrium in the process of electric heating is measured, and the heat dissipation coefficient H of the solid sample is determined based on the relationship between the actual power of the sample and the temperature change * .

[0008] (2) the maximum temperature change ΔT2 of the solid sample when reaching thermal equilibrium under irradiation of the light source is monitored, and the photo-thermal conversion efficiency η of the sample is calculated according to the thermal equilibrium equation shown in formula (1):

[0009]

[0010] Wherein I0 is the light power of the light source, A is the absorbance of the sample itself, and ΔT2 is the maximum temperature change of the sample when reaching thermal equilibrium under irradiation of the light source.

[0011] In the present application, in step (1), the input power of the sample and the maximum temperature change ΔT1 of the solid sample when reaching thermal equilibrium are obtained by adjusting the input power of the power supply, and then the slope is obtained by linear fitting, which is the heat dissipation coefficient H of the sample * .

[0012] In the present application, the solid sample is an inorganic solid material or an organic solid material without phase change in the measurement process; it can be an inorganic optoelectronic material, an organic optoelectronic material or a metal nanoparticle.

[0013] The present application also provides a solid photo-thermal conversion efficiency measuring device based on the photoelectric equivalent principle, which comprises a light source system, a power supply system, a temperature measuring instrument, a resistance sheet and a heat insulation plate; the power supply system adopts a programmable direct current power supply, and the power supply system and the resistance sheet are connected by wires; the solid sample is close to the upper surface of the resistance sheet, and the heat insulation plate is arranged below the resistance sheet; the temperature measuring instrument is used for measuring the temperature change of the solid sample in the process of heating by the resistance sheet.

[0014] In the present application, the light source system comprises a xenon lamp and a light power meter.

[0015] In the present application, the temperature measuring instrument adopts an infrared thermal imager; and the material of the heat insulation plate is polystyrene plastic.

[0016] In the present application, the thickness of the resistance sheet is within 0.8 mm.

[0017] The working principle of the present application is introduced as follows:

[0018] When the light source irradiates the solid sample, the sample will absorb light energy and convert it into heat energy, which can be calculated by the energy conservation formula, i.e. formula (1), to calculate the energy conversion efficiency of the sample from light energy to heat energy, wherein the energy term Q j includes the input and output energy of the sample, m and c pThese are the sample mass and heat capacity, respectively; T is the sample temperature; and t is the measurement time.

[0019] Equation (1) describes the general thermal equilibrium equation for the sample:

[0020]

[0021] Formula (2) describes the thermal equilibrium equation of the sample under thermal equilibrium conditions. These two formulas are used together to analyze and measure the thermal response characteristics of the sample, such as the temperature change of the sample's heat dissipation coefficient under different conditions, which helps to understand the thermophysical properties of the sample. The photoelectric equivalent method (formulas (2)-(3)) used in this invention simulates the temperature change under photothermal conditions by electric heating to examine the heat dissipation properties of the sample. The heat dissipation coefficient is an intrinsic property of the sample and is independent of the heat source. Therefore, by adjusting different input powers, a scatter plot of the input power and the maximum temperature change of the sample can be obtained. Then, by linear fitting, its slope can be obtained. According to formula (2), the slope is the heat dissipation coefficient of the sample.

[0022] P * -H * ΔT1=0 (2)

[0023]

[0024] Where ΔT1 is the maximum temperature change of the sample reaching thermal equilibrium under electric heating, ΔT2 is the maximum temperature change of the sample reaching thermal equilibrium under light source irradiation, and P * H is the actual thermal power received by the sample. * P is the heat dissipation coefficient of the sample obtained through linear fitting in the electric heating module. 输出 S is the output power of the resistor in the sample plane. 接触 S is the contact area between the resistor and the sample. 表面 P is the surface area of ​​the resistor. 输入 is the input power of the resistor, r is the radius of the contact area, and h is the thickness of the resistor sheet;

[0025] Based on the heat dissipation coefficient H of the sample * Then the photothermal conversion efficiency η of the sample can be calculated by the heat balance equation, i.e., formula (4), where I0 is the light power of the light source, A is the absorbance of the sample itself, ΔT1 is the maximum temperature change of the sample to reach thermal equilibrium under electric heating, and ΔT2 is the maximum temperature change of the sample to reach thermal equilibrium under the irradiation of the light source.

[0026] I0Aη-H * ΔT2=0 (4).

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] (1) The present invention has a wide range of testing capabilities. The test samples are no longer limited to liquid or colloidal nanoparticle solutions, but can test solids such as inorganic nanoparticles and organic matter.

[0029] (2) This invention overcomes the limitations of traditional methods, which are usually limited by the overestimation of the mass term of the measurement system and the inaccuracy of the fitting of the heat dissipation coefficient, and can more accurately evaluate the photothermal conversion efficiency of the sample. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the device of the present invention, showing the light source system, solid sample stage, heat insulation plate, temperature measurement system, and electrothermal conversion module and photoelectric conversion module. Calculating the photothermal conversion efficiency of the sample involves two steps: electrothermal measurement and photothermal measurement. Electrothermal measurement: The sample is heated by setting the input power of the power supply, and the temperature evolution of the sample from its initial state to thermal equilibrium is monitored. Multiple electrothermal tests are performed under different input powers, and the temperature change is linearly fitted to the power to determine the heat dissipation coefficient of the sample. Photothermal measurement: The maximum temperature change of the sample is monitored under a simulated light source. The photothermal conversion efficiency of the sample is calculated according to the heat balance equation.

[0032] Figure 2 This is a physical diagram of the experimental apparatus of the present invention. Detailed Implementation

[0033] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific illustrations.

[0034] This invention provides a solid-state photothermal conversion efficiency measurement device based on the photoelectric equivalence principle, such as... Figure 1As shown, it includes a light source system, a power supply system, a temperature measuring instrument, a resistance element, and a heat insulation plate. The light source system provides stable and controllable illumination conditions to ensure the accuracy and repeatability of the measurement results. The power supply system provides stable input current and voltage. The resistance element is in close contact with the surface of the solid sample to accurately sense changes in sample temperature and reduce the influence of thermal radiation and convection. The temperature measuring instrument uses an infrared thermal imager to accurately measure the temperature change of the sample during the heating process and record the temperature evolution of the sample. A heat insulation plate is placed under the sample to reduce the influence of the environment. The material of the heat insulation plate can be polystyrene plastic (foam plastic). In this embodiment, the light source system includes a xenon lamp and a light power meter. The xenon lamp serves as a stable output light source, and the light power density is adjusted to 100 W / cm². 2 To simulate real-world sunlight exposure and record temperature changes.

[0035] The power supply system employs a programmable DC power supply, which allows adjustment of the input power to test the electric heating process of the sample under different power levels, thus obtaining a more accurate heat dissipation coefficient for the sample. Sufficiently thin resistance elements are used to minimize the effects of heat convection and radiation during heating, further enhancing the accuracy of the experimental results.

[0036] Figure 2 The photographs show the experimental setup of this invention, all of which is placed inside a sealed working chamber. All instruments should be calibrated before measurement. Simultaneously, the ambient temperature outside the working chamber should be kept stable.

[0037] The specific testing process steps of this invention are as follows:

[0038] Step 1: Place a resistance element at the center of the upper end of the insulating foam, place the sample on the resistance element, and ensure it is heated evenly. Set a fixed test area on the infrared thermal imager and monitor the temperature change of the sample using the infrared thermal imager. Set the input power to P using a programmable DC power supply. 输入 (0-0.2W), start electric heating and record the average temperature of the test area. When the sample reaches thermal equilibrium, stop heating, save the temperature change curve, and after the sample temperature and ambient temperature stabilize, change the value of P0 and repeat the steps. Calculate P according to the formula. * Extract the maximum average temperature change from the temperature change curve. Based on the formula, use P... * By performing a linear fit with the temperature change ΔT, we obtain H. * .

[0039] Step 2: Remove the resistor and fix the test area for monitoring the temperature change of the sample. Depending on the testing requirements (the photothermal conversion efficiency of the sample varies under different light powers; for example, to evaluate the photothermal conversion efficiency of the sample under sunlight, I0 is set to 100 mW / cm²). 2The power of the incident light from the xenon lamp was set to I0 to simulate sunlight irradiation of the sample. An infrared thermal imager was used to record the temperature changes in the test area under light heating. Heating was stopped when the sample reached thermal equilibrium, and the temperature change curve was saved. The maximum average temperature change was extracted from the temperature change curve.

[0040] Finally, after obtaining the above parameters, the photothermal conversion efficiency of the sample under this optical power is calculated according to the formula.

[0041] Example 1

[0042] In the examples, the photothermal conversion efficiency of the traditional photothermal material graphene was tested.

[0043] First, a 10×10 mm monolayer graphene film was tightly attached to a resistive sheet. Three different input powers (0.03 W, 0.05 W, 0.08 W, and 0.11 W) were applied using a programmable DC power supply for electric heating. The temperature evolution curves were recorded, and the maximum average temperature rise ΔT was extracted. The actual heat power P received by the sample was then used as the basis for the calculation. * Using ΔT as the vertical axis and ΔT as the horizontal axis, a linear fit is performed. The slope of the fitted line is the heat dissipation coefficient H of the sample. * H was measured * The value is 0.0025 W / ℃, where the coefficient of determination R for linear fitting is... 2 =0.998, slope H * The standard error is ±0.0003 W / ℃. Subsequently, the resistor was removed, and a xenon lamp was used to provide 100 mW / cm². 2 The graphene sample was photothermally heated under sunlight, and the equilibrium temperature rise ΔT was measured to be 7.2℃. Based on the formula, the photothermal conversion efficiency of the graphene sample under one solar radiation intensity was calculated to be 89.5%.

[0044] Example 2

[0045] In the examples, the photothermal conversion efficiency of the traditional photothermal material graphene oxide was tested.

[0046] First, the graphite oxide sample was placed on a resistance plate, and an electric heating experiment was conducted using a DC power supply with input power settings of 0.03W, 0.05W, 0.07W, 0.09W, and 0.12W. Temperature change curves were obtained, and ΔT was extracted. (The last sentence appears to be incomplete and requires further context.) * The heat dissipation coefficient H is obtained by fitting the linear relationship with ΔT. * The value is 0.0033 W / ℃, indicating excellent linear fit, and R0 is... 2 The value is 0.997, H * The coefficient error is ±0.0004 W / ℃. After completing the electric heating test, a xenon lamp was used at 100 mW / cm². 2The sample was irradiated with light at a specific power density, and the equilibrium temperature rise ΔT under photothermal heating was recorded as 5.6℃. Substituting these values ​​into the formula, the photothermal conversion efficiency of graphene oxide was calculated to be 88.9%.

[0047] Example 3

[0048] In the examples, the photothermal conversion efficiency of the inorganic photothermal material MXenes was tested.

[0049] This embodiment focuses on the measurement of MXene (Ti3C2) nanosheet thin films. After the thin film sample was brought into close contact with a resistive element, DC power of 0.04W, 0.06W, 0.08W, 0.12W, and 0.16W was applied sequentially, and the temperature rise process was recorded using an infrared thermal imager. Linear fitting was performed on the electrothermal data to determine the heat dissipation coefficient H of the sample. * The value is 0.0058 W / ℃, and the goodness of fit R is... 2 =0.999, indicating an excellent linear relationship in the data, H * The standard error is ±0.0002 W / ℃. Subsequently, a light-heating test was conducted at 100 mW / cm². 2 Under illumination, the temperature rise ΔT of the sample when it reaches thermal equilibrium is 9.2℃. Calculations show that the photothermal conversion efficiency of this MXene film is as high as 92.9%.

[0050] Example 4

[0051] The photothermal conversion efficiency of traditional metal nanoparticles was tested in the examples.

[0052] This embodiment measures the photothermal conversion efficiency of gold nanorods. A gold nanorod solution (0.4–0.6 wt%) was dropped onto filter paper and uniformly distributed. Drying was then performed by heating the filter paper at 60°C to remove residual solvent. The gold nanorods were then firmly attached to a resistive element; to ensure thermal contact, thermally conductive silicone grease was applied between the bottom of the filter paper and the resistive element. Electrical heating was performed by applying DC power at 0.02 W, 0.035 W, 0.05 W, 0.07 W, and 0.15 W, and the P-value was fitted. * The heat dissipation coefficient H is obtained from the -ΔT curve. * =0.0044W / ℃, linear regression R 2 The value is 0.996, H * The coefficient error is ±0.0005W / ℃. Subsequently, a xenon lamp at 100mW / cm² was used. 2 When the gold sheet was irradiated with light, the photoinduced temperature rise ΔT was measured to be 2.4℃. The final calculated photothermal conversion efficiency of the gold nanorod sample was 68.4%.

[0053] Example 5

[0054] In the examples, the photothermal conversion efficiency of the organic photothermal material polydopamine (PDA) was tested.

[0055] PDA film samples were bonded to a resistive element, and electric heating tests were conducted by inputting DC power of 0.025W, 0.045W, 0.065W, 0.09W, and 0.14W. Linear fitting of the experimental data yielded a heat dissipation coefficient H* = 0.0019W / ℃, and a coefficient of determination R0. 2 =0.998, the standard error of the slope H* is ±0.0003 W / ℃. During the photothermal stage, 100 mW / cm² is used. 2 The sample was subjected to simulated sunlight irradiation, and the recorded equilibrium temperature rise ΔT was 7.1℃. Based on the efficiency calculation formula, the photothermal conversion efficiency of the polydopamine film was found to be 85.6%.

[0056] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as defined by the appended claims and their equivalents.

Claims

1. A method for measuring solid-state photothermal conversion efficiency based on the photoelectric equivalence principle, characterized in that, It utilizes the photoelectric equivalence principle to simulate temperature changes under photothermal conditions through electrical heating in order to investigate the heat dissipation properties of solid samples; the specific steps are as follows: (1) A programmable DC power supply is connected to a resistor, and the input power is adjusted from 0 to 0.2W. The solid sample is heated by the resistor in close contact with the solid sample. The temperature change of the solid sample when it reaches thermal equilibrium during the electrothermal process is measured. Based on the relationship between the actual power received by the sample and the temperature change, the heat dissipation coefficient H of the solid sample is determined by linear fitting and slope calculation. * ; (2) Monitor the maximum temperature change ΔT2 of the solid sample when it reaches thermal equilibrium under light source irradiation, and calculate the photothermal conversion efficiency η of the sample according to the thermal equilibrium equation shown in the formula: Where: I0 is the light power of the light source, A is the absorbance of the sample itself, and ΔT2 is the maximum temperature change of the sample when it reaches thermal equilibrium under the illumination of the light source.

2. The method for measuring solid-state photothermal conversion efficiency according to claim 1, characterized in that, By adjusting the input power of the power supply, a scatter plot of the maximum temperature change ΔT1 of the solid sample when it reaches thermal equilibrium under electric heating is obtained. Then, through linear fitting, the slope is obtained, which is the heat dissipation coefficient H of the sample. * .

3. The method for measuring solid-state photothermal conversion efficiency according to claim 1, characterized in that, The solid sample is an inorganic or organic solid material that does not undergo phase change during the measurement process.

4. A solid-state photothermal conversion efficiency measuring device based on the photoelectric equivalence principle, used to implement the solid-state photothermal conversion efficiency measuring method according to any one of claims 1-3, characterized in that, It includes a light source system, a power supply system, a temperature measuring instrument, a resistance element, and a heat insulation plate; the power supply system uses a programmable DC power supply, and the power supply system and the resistance element are connected by wires; the solid sample is in close contact with the upper surface of the resistance element, and a heat insulation plate is set below the resistance element; the temperature measuring instrument is used to measure the temperature change of the solid sample during the heating process of the resistance element.

5. The solid-state photothermal conversion efficiency measuring device according to claim 4, characterized in that, The light source system includes a stable light source and an optical power meter.

6. The solid-state photothermal conversion efficiency measuring device according to claim 4, characterized in that, The temperature measuring instrument uses an infrared thermal imager; the heat insulation board is made of polystyrene plastic.

7. The solid-state photothermal conversion efficiency measuring device according to claim 4, characterized in that, The thickness of the resistor sheet is less than 0.8mm.

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