Micro-nano particle characterization system and characterization method based on alternating current photovoltaic effect

Abstract

The invention belongs to the technical field of photoelectric detection, and particularly relates to a micro-nano particle characterization system and characterization method based on an alternating current photovoltaic effect. The two technical problems in the aspects of sensitivity and measurement precision of the existing photoelectric detection technology are solved; the sensitivity of the photoelectric detector is remarkably improved; the sensitivity bottleneck of the traditional technology is broken through; the interference of continuous laser irradiation on the micro-nano particles is effectively reduced, and the measurement precision is improved. The technical breakthroughs not only widen the application range of the photoelectric detection technology, but also provide more accurate and reliable technical means for micro-nano particle characterization, and have important scientific significance and application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of optoelectronic detection, and particularly relates to a micro-nano particle characterization system and a characterization method based on the alternating current photovoltaic effect. Background Art

[0002] The photoelectric effect is a basic process of the interaction between photons and matter, and has wide applications in the fields of energy, communication, materials science, physics, etc. The research on photodetectors has promoted the development of optoelectronics and had a profound impact on the fields of astronomy, optical computing, quantum communication, biomedicine, etc. At the same time, the photoelectric effect is applied to material characterization to study the electronic structure, physical properties and chemical composition of materials, which has wide applications in the fields of materials science, biological science, medicine, environmental science, etc.

[0003] Among them, optoelectronic detection technology plays a core role in micro-nano particle characterization. Especially in the light scattering technology, when a monochromatic light beam irradiates micro-nano particles, scattering phenomenon occurs. By measuring the scattered light energy and distribution, based on the Rayleigh scattering theory, Mie scattering theory and Fraunhofer approximation theory, the relevant physical properties of the particles are obtained. The performance of the photodetector directly determines the accuracy and range of the above measurements. Most traditional optoelectronic detection technologies rely on the photovoltaic effect, and their working principle is to expand the depletion region by applying an external voltage, thereby enhancing the light responsivity. However, the photodetectors in the prior art have the problem of insufficient sensitivity, mainly manifested as a large dark current, which is difficult to detect extremely weak light signals, resulting in a limited measurement range. Although there are some technical attempts to work under zero bias voltage to reduce the dark current, due to the low carrier separation efficiency, the photocurrent output is still greatly limited, and the sensitivity bottleneck has not been broken through, and the requirements of high-precision micro-nano particle characterization cannot be met.

[0004] In addition, in traditional optoelectronic detection technology, the measurement of the physical properties of micro-nano particles usually relies on continuous laser irradiation. However, continuous laser irradiation will cause a series of problems, including the increase in temperature around the particles and the change of the physical properties of the particles, etc., which will significantly affect the accuracy of the measurement results. Specifically, continuous laser irradiation will cause the following problems:

[0005] Thermal radiation effect: The thermal radiation effect of the continuous light field will cause the temperature around the particles to rise, thereby changing the motion state of the particles, and further affecting the physical properties of the particles. It is found that continuous light illumination will cause thermal expansion or chemical reaction changes of the particles, and these factors will cause changes in the morphology and size of the particles, thereby introducing measurement errors. In ultra-high sensitivity physical property characterization, the interference of the continuous light field on particle physical property characterization cannot be ignored.

[0006] Excitation state interference: When light irradiates the surface of particles, the energy of photons is converted into electron excitation, which may cause rearrangement or release of electrons on the particle surface, changing the chemical composition and surface morphology of the particles, thereby affecting the physical properties of the particles. In addition, under the surface plasmon resonance effect, the local electric and magnetic fields generated by the laser on the particle surface will further cause a local heating effect, which will disrupt the diffusion behavior of the particles and affect the measurement results of their physical properties.

[0007] Therefore, there are still problems that the sensitivity and measurement accuracy of existing optoelectronic detection technologies need to be further improved in the characterization of micro-nano particles. Summary of the Invention

[0008] To solve the above technical problems, the present invention provides a micro-nano particle characterization system and characterization method based on the alternating current photovoltaic effect, which solves the problems of insufficient sensitivity of existing optoelectronic detection technologies and interference caused by continuous light fields, so as to improve the accuracy and sensitivity of the physical property characterization of micro-nano particles.

[0009] The present invention is specifically realized through the following technical solutions.

[0010] The present invention provides a micro-nano particle characterization system based on the alternating current photovoltaic effect, including: A scintillating light source module for generating intermittent optical signals, and the generated intermittent optical signals are injected into the solution of particles to be characterized to generate scattered light.

[0011] An optoelectronic detection module, including an optoelectronic detector for receiving scattered light and generating an alternating current optoelectronic signal; the optoelectronic detector includes a semiconductor substrate and an ultra-thin material located on the surface of the semiconductor substrate, and the ultra-thin material is an oxide semiconductor, a nitride semiconductor or an organic material semiconductor, and the thickness of the ultra-thin material is 1 Å - 500 nm.

[0012] A signal processing module for analyzing the alternating current optoelectronic signal and outputting the physical parameters of the micro-nano particles.

[0013] Among them, the alternating current photovoltaic effect means that: in the state of no external bias voltage (0 V) or small bias voltage (-0.8 V), when light periodically irradiates the nano-scale junction interface of the material, the photon-induced excess carriers are immediately generated and quenched in the non-equilibrium state, and the electrons oscillate back and forth between the two electrodes, generating a large alternating photocurrent in the nano-scale junction. At a high switching frequency, the peak photocurrent of the alternating current is much higher than the direct current (about 2051 times). This alternating current signal does not follow Ohm's law, but conforms to the Maxwell displacement current model.

[0014] Based on the above-mentioned AC photovoltaic effect, the present invention breaks through the sensitivity bottleneck of traditional optoelectronic detection technology: traditional optoelectronic detection technology has limitations in detecting weak optical signals, with insufficient sensitivity. By introducing the AC photovoltaic effect, the present invention can obtain high AC electrical signals under zero bias, avoiding the influence of dark current, enabling the detection system of the present invention to provide ultra-high sensitivity to extremely weak optical signals, significantly improving the detection accuracy. Especially in the detection of scattered light energy of low-concentration micro-nano particles, higher detection limits and accuracies can be achieved. According to the pre-experiment results, the detector based on the AC photovoltaic effect has shown record-breaking sensitivity (6.09×10 9 %), exceeding that of traditional optoelectronic detectors by two orders of magnitude in terms of the detection ratio (5.4×10¹ 4 Jones). This enables the AC photovoltaic effect to be applied to the detection of scattered signals of ultra-low-concentration micro-nano particles, meeting the requirements of high-precision and high-sensitivity physical property characterization.

[0015] The present invention effectively suppresses the negative impact of the continuous light field: Research shows that laser irradiation has a negative impact on the measurement of the physical properties of micro-nano particles, mainly manifested in that the continuous light field causes the particles to deviate from the normal state, resulting in measurement errors. Different from traditional continuous light illumination, the present invention irradiates micro-nano particles with a flash field, making full use of the characteristics of the AC photovoltaic effect, and can effectively weaken the thermal radiation, light absorption of the continuous laser irradiation on the particles, and the change of the physical state of the particles by the excited state. By using the flash field, the micro-nano particles can maintain their motion in a more stable and near-normal state, thus ensuring the accuracy of the characterization results of the physical properties of the particles and reducing the interference caused by the continuous light field.

[0016] Optimizing the detection material and structure design: The detector adopted by the present invention has a nano-scale structure, and makes full use of the behavior effect of excess carriers in the non-equilibrium state in the above-mentioned AC photovoltaic effect to enhance the enhancement effect of the AC photovoltaic effect. Through this design, the detector can work normally under low voltage (0V) and has self-driving characteristics. This not only greatly reduces the generation of dark current, but also can provide strong signal output, significantly improving the sensitivity of the detector. At the same time, the optimization of the device structure also helps to improve the detection efficiency of the AC photovoltaic effect, providing a higher-performance detection platform for the physical property characterization of micro-nano particles.

[0017] Providing a new physical property characterization technology: By deeply studying and verifying the basic physical processes and principles of the alternating current photovoltaic effect, the present invention provides a brand-new technical means for characterizing the physical properties of micro-nano particles. Compared with traditional detection methods, the alternating current photovoltaic effect can break through the limitations of traditional technologies and achieve physical property detection with higher sensitivity and accuracy, especially suitable for characterizing various physical properties of micro-nano particles in complex physical environments. Combining dynamic light scattering (DLS) and multi-angle light scattering (MALS) technologies, the present invention can accurately measure physical parameters such as the diffusion coefficient, particle size distribution, molecular weight, radius of gyration, second virial coefficient, concentration, and Zeta potential of micro-nano particles, providing a more accurate and comprehensive analysis tool for the study of the physical properties of micro-nano particles.

[0018] Preferably, the intermittent light signal is a pulsed laser with different waveforms.

[0019] Preferably, the scintillating light source module includes a signal generator, a laser driver, and a laser. The signal generator is used to output electrical signals with different waveforms, and the laser driver is used to receive the electrical signals and control the laser to output pulsed laser with a target waveform, frequency, and intensity.

[0020] Preferably, an attenuation module is further provided between the laser and the solution of the particles to be characterized, which is used to attenuate the pulsed laser output by the laser.

[0021] Preferably, the ultra-thin functional material has a thickness of 1 Å to 500 nm, including but not limited to: tin dioxide, titanium dioxide, zinc oxide, indium tin oxide, aluminum oxide, hafnium oxide, zinc sulfide, zinc selenide, molybdenum disulfide, tungsten disulfide, black phosphorus, graphene, hexagonal boron nitride, and various transition metal sulfides; perovskite optoelectronic materials include methylammonium lead iodide perovskite, methylammonium lead bromide perovskite, methylammonium lead chloride perovskite, methylammonium lead halide mixed perovskite (such as iodine bromide, iodine chloride mixed halides), cesium lead halide perovskite (such as cesium lead bromide, cesium lead iodide bromide, cesium lead chloride perovskite), lead tin mixed halide perovskite, and bismuth silver double halide double perovskite; organic semiconductor materials include poly(3-hexylthiophene), poly(3,4-ethylenedioxythiophene) and its sulfonate derivatives, pentacene, anthracene, dibenzoanthracene, fullerene, nickel phthalocyanine, small molecule phthalocyanine, polybenzothiophene, polyfluorene and its copolymers, and other small molecule organic dyes; nickel oxide, various copper oxides, gallium nitride, aluminum nitride, and MXene.

[0022] The semiconductor substrate includes, but is not limited to: silicon, gallium arsenide, silicon carbide, indium phosphide, gallium nitride, aluminum nitride, germanium, gallium oxide, zinc oxide, cadmium telluride, silicon-germanium alloy, silicon-on-insulator oxide, and flexible organic substrates such as polyimide film, polyethylene terephthalate film, polycarbonate film, polydimethylsiloxane film, and polyvinylidene fluoride film, etc. Preferably, the ultra-thin functional material is selected from oxide materials with relatively high stability, such as wide-bandgap oxides like tin dioxide, titanium dioxide, aluminum oxide, zirconium oxide, magnesium oxide, hafnium oxide; or silicon-based semiconductor materials such as silicon nitride, aluminum nitride; two-dimensional carbon-based materials such as graphene and transition metal sulfides with excellent stability (MoS2, WS2), etc. can also be preferably used.

[0023] Preferably, metal, non-metal or rare earth doping elements are introduced into the ultra-thin material to adjust electrical and optical properties such as carrier concentration, mobility, optical absorption, and bandgap width; the doping elements include, but are not limited to: aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide are generated by doping with metal elements such as aluminum, gallium, indium; fluorine-doped tin dioxide, nitrogen-doped titanium dioxide, sulfur-doped titanium dioxide, phosphorus-doped titanium dioxide are generated by doping with non-metal elements such as fluorine, nitrogen, sulfur, phosphorus; tin dioxide, titanium dioxide and other transition metal oxides are further doped with transition metal elements such as titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc; rare earth-doped transition metal sulfides are prepared by doping with rare earth elements such as neodymium, terbium, cerium; in addition, boron can also be introduced into graphene, iron can be introduced into MXene, and cobalt or nickel can be introduced into transition metal oxides such as manganese oxide, iron oxide; the doping can be carried out in a single doping, co-doping or gradient doping manner, and the doping concentration is preferably 0.001 at% - 20 at%.

[0024] Directly prepare structures such as thin films, nanowires, arrays, or nanorods on a semiconductor substrate. The methods used include, but are not limited to, solution methods (such as hydrothermal method, hydrothermal-assisted sol-gel method, sol-gel method, chemical bath deposition (CBD), dipping method, spin coating method), self-assembly methods (such as Langmuir–Blodgett film method, molecular self-assembly SAM, layer-by-layer self-assembly LbL, colloidal crystal self-assembly, electric field-induced assembly, evaporation-induced assembly, and block copolymer template self-assembly), electrochemical methods (such as electrochemical deposition / electroplating), vapor deposition methods (such as chemical vapor deposition CVD and its metal-organic MOCVD, low-pressure LPCVD, plasma-enhanced PECVD, atomic layer deposition ALD, molecular beam epitaxy MBE), physical vapor deposition PVD (such as thermal evaporation, electron beam evaporation E-beam, DC, RF, and reactive modes of magnetron sputtering, ion beam-assisted deposition IBAD, multi-arc ion plating, pulsed laser deposition PLD, electron cyclotron resonance deposition ECR, and molecular beam physical vapor deposition MBPVD), template-assisted methods (hard templates, soft templates, nanoimprint lithography NIL), vapor-liquid-solid growth method (VLS), chemical etching (wet etching, dry etching, reactive ion etching, plasma etching), printing and coating technologies (inkjet printing, screen printing, microcontact printing, drop coating, spraying), and electrospinning, etc. These methods for preparing nanostructures and thin films can be used simultaneously, that is, one or more of these methods can be used to prepare composite nanostructures. The preferred methods for directly preparing structures such as thin films, nanowires, arrays, or nanorods on a semiconductor substrate are the hydrothermal method and vapor deposition methods (ALD, MBE, PVD, CVD, etc.).

[0025] Preferably, the photoelectric detection module further includes a low-noise preamplifier or a transimpedance amplifier and an oscilloscope. The low-noise preamplifier or transimpedance amplifier and the oscilloscope are connected to the photodetector and are used to extract the current signal generated by the scattered light and transmit it to the signal processing module for analysis.

[0026] The present invention also provides a method for characterizing micro-nano particles based on the alternating current photovoltaic effect. The characterization is carried out using the above-mentioned photodetector device and includes the following steps: In an optical dark box, inject the intermittent optical signal generated by the scintillating light source module into the solution of the particles to be characterized to generate scattered light. Use the photoelectric detection module to receive the scattered light and generate an alternating current photoelectric signal, and use the signal processing module to analyze the alternating current photoelectric signal and output the physical parameters of the micro-nano particles.

[0027] Preferably, the analysis method includes: the change in the intensity of the light scattered by the particles causes a corresponding change in the response current of the photodetector. Substituting the measured changing response currents at different angles into the characteristic curve of the relationship between the response current of the photodetector and the light intensity, the absolute value of the light scattering intensity of the particles at different angles and its fluctuation over time can be obtained. Based on the absolute value of the obtained scattered light intensity and its fluctuation over time, physical parameters of the micro-nano particles are obtained. The physical parameters include the diffusion coefficient of the particles, the average particle size and particle size distribution, concentration, zeta potential of the particles, molecular weight, two-dimensional virial coefficient, radius of gyration, and particle shape.

[0028] Compared with the prior art, the present invention has the following effects: The present invention applies the alternating current photovoltaic response effect to micro-nano particle characterization for the first time. By utilizing the unique advantages of the alternating current photovoltaic effect, the problems of insufficient sensitivity of existing photoelectric detection technologies and interference caused by continuous light fields are solved, so as to improve the accuracy and sensitivity of micro-nano particle physical property characterization. Specifically, it includes: A scintillating light source module for generating intermittent optical signals. The generated intermittent optical signals are incident into the solution of the particles to be characterized to generate scattered light. A photoelectric detection module includes a photodetector for receiving the scattered light and generating an alternating current photoelectric signal. The photodetector includes a semiconductor substrate and an ultra-thin material located on the surface of the semiconductor substrate. The ultra-thin material is an oxide semiconductor, a nitride semiconductor, a perovskite semiconductor, or an organic material semiconductor, and the thickness of the ultra-thin material is 1 Å - 500 nm. A signal processing module for analyzing the alternating current photoelectric signal and outputting the physical parameters of the micro-nano particles.

[0029] With the above device, in the state of no external bias voltage (0 V) or a small bias voltage (-0.8 V), under periodic light illumination, photon-induced non-equilibrium excess carriers oscillate back and forth between the two electrodes, generating an extremely high alternating current signal, which significantly improves the sensitivity of the photodetector. Experimental results show that compared with traditional photoelectric detection technologies, the sensitivity of the present invention has been improved by two orders of magnitude, and ultra-high sensitivity micro-nano particle physical property characterization can be achieved under extremely weak light illumination conditions. This breakthrough not only broadens the application scope of photoelectric detection technologies, but also significantly improves the limit of concentration detection, providing a more accurate technical means for micro-nano particle characterization.

[0030] Different from traditional continuous laser irradiation, the present invention adopts an intermittent light illumination mode, significantly reducing the thermal radiation effect and excited state interference of continuous light illumination on micro-nano particles. Experiments have proved that this method can provide more accurate micro-nano particle physical property characterization results, significantly reducing the measurement error, and providing reliable technical support for high-precision micro-nano particle characterization.

[0031] By innovatively introducing the alternating current photovoltaic effect, the present invention solves two major technical problems in the existing optoelectronic detection technology in terms of sensitivity and measurement accuracy: significantly improving the sensitivity of the photodetector and breaking through the sensitivity bottleneck of traditional technologies; effectively reducing the interference of continuous laser irradiation on micro-nano particles and improving the measurement accuracy. These technical breakthroughs not only broaden the application scope of optoelectronic detection technology but also provide a more accurate and reliable technical means for micro-nano particle characterization, with important scientific significance and application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 FIG. is a schematic structural diagram of a micro-nano particle characterization system based on the alternating current photovoltaic effect.

[0033] Figure 2 FIG. shows the relationship between the light scattering technology and characterization parameters involved in the present invention.

[0034] Figure 3 FIG. is a schematic diagram of the improvement idea of the micro-nano particle characterization system based on the alternating current photovoltaic effect of the present invention.

[0035] Figure 4 FIG. is a graph showing the variation of the device response current with the concentration of anatase TiO2 particle dispersion with an average particle size of 100 nm.

[0036] Figure 5 FIG. is a curve graph showing the relationship between the response current and particles of different average sizes. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention will be further described below in conjunction with specific embodiments and drawings, but the described embodiments shall not be construed as limiting the present invention. In the following embodiments, the experimental methods and detection methods are all conventional methods unless otherwise specified; the reagents and materials are all commercially available unless otherwise specified.

[0038] The present invention provides a micro-nano particle characterization system based on the alternating current photovoltaic effect, as Figure 1 shown, including a scintillating light source module for generating an intermittent optical signal, and the generated intermittent optical signal is incident on the solution 4 of the particles to be characterized to generate scattered light 10. The angle is 13° - 173°, preferably 90°.

[0039] an optoelectronic detection module for receiving the scattered light 10 and generating an alternating current optoelectronic signal.

[0040] a signal processing module 7 for analyzing the alternating current optoelectronic signal and outputting the physical parameters of the micro-nano particles. The signal processing module 7 is a computer.

[0041] Preferably, the intermittent optical signal is a pulsed laser with different waveforms, which can be a sine wave, a square wave or a triangular wave.

[0042] The scintillating light source module includes a signal generator 1, a laser driver 2 and a laser 3. The signal generator 1 is used to output electrical signals with different waveforms. The laser driver 2 is used to receive the electrical signals and control the laser 3 to output pulsed laser with a target waveform, frequency and intensity. The laser driver 2 plays a bridging role, converting the electrical signals of the signal generator 1 into current signals for driving the laser, ensuring that the laser outputs corresponding optical signals according to the target waveform. Among them, the frequency range is 0.01 Hz - 100 GHz, and the intensity range is 1 pW - 50 W.

[0043] Preferably, an attenuation module 8, specifically a neutral density attenuation sheet, is further provided between the laser 3 and the solution 4 of the particles to be characterized, for attenuating the pulsed laser output by the laser. A beam terminator 9 is further provided on the other side of the solution 4 of the particles to be characterized away from the attenuation module 8.

[0044] Preferably, the photoelectric detection module includes a photodetector 5, and the photodetector 5 includes a semiconductor substrate and an ultrathin material located on the surface of the semiconductor substrate. The ultrathin material is an oxide semiconductor, a nitride semiconductor or an organic material semiconductor.

[0045] Preferably, the ultrathin functional material has a thickness of 1 Å - 500 nm, including but not limited to: tin dioxide, titanium dioxide, zinc oxide, indium tin oxide, aluminum oxide, hafnium oxide, zinc sulfide, zinc selenide, molybdenum disulfide, tungsten disulfide, black phosphorus, graphene, hexagonal boron nitride and various transition metal sulfides; perovskite optoelectronic materials include methylammonium lead iodide perovskite, methylammonium lead bromide perovskite, methylammonium lead chloride perovskite, methylammonium lead halide mixed perovskite (such as iodine bromine, iodine chlorine mixed halide), cesium lead halide perovskite (such as cesium lead bromide, cesium lead iodide bromide, cesium lead chloride perovskite), lead tin mixed halide perovskite and bismuth silver double halide double perovskite; organic semiconductor materials include poly(3-hexylthiophene), poly(3,4-ethylenedioxythiophene) and its sulfonate derivatives, pentacene, anthracene, dibenzoanthracene, fullerene, nickel phthalocyanine, small molecule phthalocyanine, polybenzothiophene, polyfluorene and its copolymers and other small molecule organic dyes; nickel oxide, various copper oxides, gallium nitride, aluminum nitride and MXene. The semiconductor substrate includes but not limited to: silicon, gallium arsenide, silicon carbide, indium phosphide, gallium nitride, aluminum nitride, germanium, gallium oxide, zinc oxide, cadmium telluride, silicon germanium alloy, silicon on insulating silicon oxide layer, and flexible organic substrates such as polyimide film, polyethylene terephthalate film, polycarbonate film, polydimethylsiloxane film and polyvinylidene fluoride film, etc.

[0046] Preferably, metal, non-metal or rare earth doping elements are introduced into the ultra-thin functional material to adjust electrical and optical properties such as carrier concentration, mobility, optical absorption and bandgap width; the doping elements include but are not limited to: aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide are generated by doping with metal elements such as aluminum, gallium, indium, etc.; fluorine-doped tin dioxide, nitrogen-doped titanium dioxide, sulfur-doped titanium dioxide, phosphorus-doped titanium dioxide are generated by doping with non-metal elements such as fluorine, nitrogen, sulfur, phosphorus, etc.; tin dioxide, titanium dioxide and other transition metal oxides are further doped with transition metal elements such as titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, etc.; rare earth-doped transition metal sulfides are prepared by doping with rare earth elements such as neodymium, terbium, cerium, etc.; in addition, boron can also be introduced into graphene, iron can be introduced into MXene, and cobalt or nickel can be introduced into transition metal oxides such as manganese oxide and iron oxide; the doping can be carried out in a single doping, co-doping or gradient doping manner, and the doping concentration is preferably 0.001 at% to 20 at%.

[0047] Structures such as thin films, nanowires, arrays or nanorods are directly prepared on a semiconductor substrate, and the methods used include but are not limited to solution methods (such as hydrothermal method, hydrothermal-assisted sol-gel method, sol-gel method, chemical bath deposition (CBD), dipping method, spin coating method), self-assembly methods (such as Langmuir–Blodgett film method, molecular self-assembly SAM, layer-by-layer self-assembly LbL, colloidal crystal self-assembly, electric field-induced assembly, evaporation-induced assembly and block copolymer template self-assembly), electrochemical methods (such as electrochemical deposition / electroplating), vapor deposition methods (such as chemical vapor deposition CVD and its metal organic MOCVD, low pressure LPCVD, plasma enhanced PECVD, atomic layer deposition ALD, molecular beam epitaxy MBE), physical vapor deposition PVD (such as thermal evaporation, electron beam evaporation E-beam, direct current, radio frequency and reactive modes of magnetron sputtering, ion beam assisted deposition IBAD, multi-arc ion plating, pulsed laser deposition PLD, electron cyclotron resonance deposition ECR and molecular beam physical deposition MBPVD), template-assisted methods (hard template, soft template, nanoimprint NIL), vapor-liquid-solid growth method (VLS), chemical etching (wet etching, dry etching, reactive ion etching, plasma etching), printing and coating technologies (inkjet printing, screen printing, microcontact printing, drop coating, spraying) and electrospinning and other processes.

[0048] Preferably, the photodetector 5 is connected to a low-noise preamplifier or a transimpedance amplifier and an oscilloscope 6, which are used to extract the current signal generated by the scattered light and transmit the signal to the signal processing module 7 for processing and analysis.

[0049] The present invention also provides a method for characterizing micro-nano particles based on the alternating current photovoltaic effect, which is characterized by using the above-mentioned photodetector device, and includes the following steps: In an optical dark box ( Figure 1 the part indicated by the dashed line), an intermittent optical signal generated by a flashing light source module is injected into a solution of particles to be characterized, so as to generate scattered light.

[0050] A photoelectric detection module is used to receive the scattered light and generate an alternating current photoelectric signal, and a signal processing module is used to analyze the alternating current photoelectric signal and output physical parameters of the micro-nano particles.

[0051] Preferably, the analysis method includes: analyzing the relationship characteristic curve between the alternating current photovoltaic effect current and the incident light intensity to obtain the absolute value of the particle scattered light intensity and its fluctuation over time, so as to provide data support for further calculating the physical properties of the particles. Combining the technical principles of dynamic light scattering (DLS), static light scattering (SLS) and multi-angle light scattering (MALS), physical parameters such as the diffusion coefficient, average particle size, particle size distribution and concentration of the particles can be calculated in detail. At the same time, referring to the principle of electrophoresis light scattering (ELS), the present invention can also add electrode plates on both sides of the cuvette, so as to calculate the zeta potential of the particles by using the electrophoresis light scattering technology. The core advantage of this technology is to achieve precise detection of the interaction between micro-nano particles and the flashing pulsed laser through the ultra-high sensitivity of the light response of the alternating current photovoltaic effect, so as to establish an accurate relationship between the detection signal and the related physical properties of the particles. This method not only has extremely high sensitivity, but also can achieve high-precision physical property characterization in low-concentration particle samples, and is particularly suitable for complex physical environments and synchronous detection of multiple physical parameters.

[0052] The physical parameters that can be characterized by the present invention include the diffusion coefficient of the particles, average particle size and particle size distribution, concentration, zeta potential of the particles, molecular weight, second virial coefficient, radius of gyration, particle shape, etc. By changing the experimental conditions and adjusting the parameters of the detector, various physical property data of the particles can be obtained, which makes the present invention have a wide range of applications and can provide a multi-parameter and all-round physical property characterization tool for the research of micro-nano particles. Figure 2 Further clarifies the light scattering technology involved in the present invention and its relationship with physical parameters. Through the quantitative relationship between the scattered light intensity of micro-nano particles and various physical properties, the present invention can accurately analyze the behavior of particles in the light field and provide high-precision quantitative analysis for their physical properties. Compared with traditional photoelectric detection technology, although the basic light scattering principle and formula have not changed, the innovation of the present invention lies in its combination of a flashing field and the alternating current photovoltaic effect, which makes this technology show great advantages in terms of sensitivity and anti-interference ability.

[0053] The detection system of the present invention can obtain multiple physical parameters of particles, such as particle size distribution, shape, concentration, hydrodynamic radius, etc., by adjusting the analysis method of detection signals. These parameters are not only of great significance for the basic research of micro-nano particles, but also can be widely applied in the fields of nano materials, nano medicine, environmental monitoring, etc. Due to the close relationship between the detection signals and various physical properties of micro-nano particles, the present invention can not only provide high-precision characterization of the physical properties of micro-nano particles, but also meet the requirements of different particle systems and different experimental environments, with great practical potential and popularization value.

[0054] It should be noted that, as Figure 3 shown, the present invention uses a flash pulsed laser and a photodetector based on the alternating current photovoltaic effect for the physical property characterization of micro-nano particles. Its core test principle lies in combining the scattering of micro-nano particles on the flash laser with the characteristics of the alternating current photovoltaic effect, and by detecting the relationship between the scattered light intensity and the current fluctuation, the physical parameters of the particles are deduced. Through this principle, the present invention can achieve high-precision and multi-parameter characterization of micro-nano particles. The key points are:

[0055] Application of new physical effects: The alternating current photovoltaic effect is applied to the characterization of micro-nano particles for the first time, and ultra-high sensitivity detection is realized by using the alternating current photoelectric signals generated at the moment of light on and off.

[0056] It should be noted that the alternating current photovoltaic effect is: In the state of no external bias voltage (0 V), when light periodically irradiates the nano-scale junction interface of the material, the photon-induced excess carriers are immediately generated and quenched in the non-equilibrium state, and the electrons oscillate back and forth between the two electrodes, generating a large alternating photocurrent in the nano-scale junction. At a high switching frequency, the peak alternating photocurrent is much higher than the direct current (about 2051 times). This alternating current signal does not follow Ohm's law, but conforms to the Maxwell displacement current model. Under periodic light illumination, the photon-induced non-equilibrium excess carriers oscillate back and forth between the two electrodes, generating an extremely high alternating current signal. The reason for this phenomenon is that under non-equilibrium conditions, the excess carriers generated by the semiconductor cause a relative shift between the quasi-Fermi levels at the material interface, resulting in an imbalance in the charge distribution, and the electrons flow in the external circuit to establish a new balance to balance the potential difference between the electrodes.

[0057] Material Innovation: Ultra-thin film materials (with a thickness of 1 Å - 500 nm) are adopted. Currently, titanium dioxide (TiO2) and tin dioxide (SnO2) are preferably used, and other oxides, nitrides, perovskites, and organic materials can also be used. The nano-scale junction structure enables this material design to significantly enhance the performance of the alternating current photovoltaic effect. The nano-scale structured materials can provide a higher surface area and more non-equilibrium carriers, thus promoting the generation of the alternating current photovoltaic effect. The selection of this material structure endows the device with a higher response ability when detecting weak signals and can effectively characterize the physical properties of extremely small particles.

[0058] Light Source Design: Scintillation light is used as the light source, and alternating current optoelectronic signals are generated through the on and off instants of the light, avoiding the thermal radiation effect and excited state interference caused by continuous laser irradiation.

[0059] Self-driven Characteristic: Without applying any external voltage or under a weak voltage (<0.8V) Through the scattering of scintillation light by micro-nano particles, the detection of scattered light is realized by using the alternating current photovoltaic effect.

[0060] The present invention brings significant improvements in all aspects by adopting the alternating current photovoltaic effect optoelectronic detection technology, specifically including: Improvement in Detection Performance: The present invention adopts the alternating current photovoltaic effect as the core detection principle. Compared with traditional optoelectronic detection technologies, its greatest advantage lies in its ultra-high sensitivity to light. The alternating current photovoltaic effect can generate a strong response under extremely weak light signals, enabling the present invention to be used for high-precision detection of low-concentration target substances. This ultra-high sensitivity light response significantly improves the detection limit, especially suitable for the detection and physical property characterization of low-concentration micro-nano particles, effectively improving the deficiencies of traditional technologies in this regard. In addition, since ultra-thin materials (polycrystalline, single-crystalline, or amorphous are all acceptable) are used instead of single-crystalline materials prepared at high temperatures, the preparation cost of the present invention is significantly reduced, and the material selection is extensive, further reducing the material cost.

[0061] Low Cost: The optoelectronic detector of the present invention uses ultra-thin materials, avoiding the high-temperature preparation process required for traditional single-crystalline materials and significantly reducing the preparation cost. Ultra-thin materials are not only inexpensive but also have a wide range of material selections, including but not limited to oxide materials such as titanium dioxide (TiO2) and tin dioxide (SnO2), nitride materials, perovskite materials, and organic materials. This low-cost material selection and preparation process endow the present invention with significant economic advantages and are suitable for large-scale production and application.

[0062] Low energy consumption: The photodetector of the present invention has a self-driven characteristic and can operate without an external bias voltage. Different from traditional photodetectors that require an externally applied bias voltage, the device of the present invention can operate under the condition of 0V. The advantage of this characteristic is that it can provide a strong signal output without increasing additional energy consumption while maintaining an extremely low dark current. This makes the system operation more convenient, can be widely applied to different experimental environments, and reduces the complexity and energy consumption of traditional photodetectors during use. In addition, since no externally applied voltage is required for driving, the energy consumption of the present invention is significantly reduced, further enhancing its economic efficiency and environmental friendliness in practical applications.

[0063] The application of the flash field reduces the negative impact of the continuous light field: The present invention innovatively uses the flash field as the laser irradiation source. Compared with the traditional continuous light illumination method, the flash field can effectively reduce the thermal radiation, light absorption, and particle state changes caused by the laser to micro-nano particles during operation. Research shows that the continuous light field may cause micro-nano particles to deviate from the normal state, thereby affecting the accuracy of physical property measurement. By using the flash field, micro-nano particles can maintain a relatively stable state when receiving short-pulse lasers, thus improving the accuracy of particle physical property characterization. This design not only improves the measurement accuracy but also reduces the energy consumption caused by continuous light illumination, further reducing the overall energy consumption of the system.

[0064] Lower concentration detection limit and higher concentration discrimination: Due to the ultra-high sensitivity of the ac photovoltaic effect, the present invention can break through the detection limit of traditional technologies and achieve the detection of micro-nano particles at extremely low concentrations. By improving the resolution of the detector, the present invention can more accurately distinguish target substances with different concentrations and has a higher concentration discrimination. This advantage enables the present invention to provide higher measurement accuracy and signal-to-noise ratio in the measurement of micro-nano particles, especially in the case of low concentrations and weak signals. At the same time, due to the use of low-cost materials and low-energy consumption design, the present invention maintains a low economic cost and energy consumption while achieving high-precision detection.

[0065] Comprehensive advantages and application prospects: By introducing the ac photovoltaic effect, novel self-made devices, and the application of the flash field, the present invention not only improves the sensitivity and accuracy of micro-nano particle characterization but also significantly improves various limitations in traditional photodetection technologies, providing a new technical means for high-precision and multi-parameter physical property characterization of micro-nano particles. These remarkable effects make the present invention have broad application prospects in the fields of nanotechnology, physical chemistry research, and related fields. In addition, the low-cost and low-energy consumption characteristics of the present invention make it have great market potential in the fields of industrial detection, environmental monitoring, biomedicine, etc., and can meet the needs of large-scale applications.

[0066] To further illustrate the present invention, the following tests were conducted on the present invention: (1)Detection of low-concentration micro-nano particles A photodetector based on the ac photovoltaic effect is used for the detection of low-concentration micro-nano particles.

[0067] Step 1: By adjusting the laser pulse frequency (200 Hz) and intensity (32.4 mW), the square-wave pulsed laser is irradiated onto the micro-nano particles suspended in the solution (in an optical dark box) at an angle of 90°.

[0068] Step 2: The scattered light is received by the photodetector to obtain a current value, and the scattered light intensity signal is measured. The data is analyzed, and the results are as Figure 4 shown. The photodetector includes a P-type silicon substrate, on which a 15-nm TiO2 thin film is deposited as the active layer. Subsequently, ITO and aluminum electrodes are deposited on the surface of TiO2 and the back of the P-type silicon substrate, respectively. Figure 4 This is the change of the device response current with the concentration of the anatase TiO2 particle dispersion with an average particle size of 100 nm. The results show that the detector of the present invention can successfully extract the scattered signal of the particles at such a low concentration, and the detection accuracy is greatly improved. Compared with the traditional photodetector, its sensitivity is significantly increased. This experiment verifies the superiority of the present invention in the detection of low-concentration micro-nano particles, showing ultra-high detection sensitivity and accuracy.

[0069] Another important feature of the present invention is the self-driven characteristic of the photodetector, that is, it can work normally without an external bias voltage (or with a very small applied bias voltage). Compared with the traditional photodetector that requires an external power supply to provide a bias voltage, the self-driven characteristic of the present invention does not require an external power supply, avoiding the negative impact that the external power supply will increase the dark current, greatly simplifying the operation process, and improving the adaptability and reliability under complex experimental conditions.

[0070] (2)Characterization of particles with different particle sizes: Using the photodetector in (1), anatase TiO2 dispersions with different average particle sizes (with a concentration of 10 -3 g / L) are tested. The square-wave pulsed laser (200 Hz, 32.4 mW) is perpendicularly incident on each particle size sample at an angle of 90°, the device response current is recorded, and the average value of the corresponding scattered light intensity is calculated. The experimental results are as Figure 5 shown. There are obvious differences in the response currents generated by samples with different particle sizes, and the particle size can be accurately mapped through the scattered light intensity, realizing a clear distinction of TiO2 particles with different average particle sizes. This experiment further proves the high sensitivity and high accuracy of the present invention in particle size characterization.

[0071] Verified by multiple test cases, the method for characterizing micro-nano particles based on the AC photovoltaic effect of the present invention has shown ultra-high sensitivity, precise detection ability, and good adaptability in the detection of particles with different concentrations, sizes, types, and crystal forms. These experimental results fully demonstrate the broad application prospects and feasibility of the present invention.

[0072] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and its equivalent technologies, these changes and modifications are also intended to be included.

Claims

1. A micro-nano particle characterization system based on the AC photovoltaic effect, characterized in that, Comprising: A flashing light source module for generating an intermittent optical signal, and the generated intermittent optical signal is incident into a solution of particles to be characterized to generate scattered light; A photoelectric detection module including a photodetector for receiving the scattered light and generating an alternating current photoelectric signal; The photodetector includes a semiconductor substrate and an ultrathin material located on the surface of the semiconductor substrate. The ultrathin material is an oxide semiconductor, a nitride semiconductor or an organic material semiconductor, and the thickness of the ultrathin material is 1 Å - 500 nm; A signal processing module for analyzing the alternating current photoelectric signal and outputting physical parameters of the micro-nano particles.

2. The micro-nano particle characterization system based on the AC photovoltaic effect according to claim 1, wherein The intermittent optical signal is a pulsed laser with different waveforms.

3. The micro-nano particle characterization system based on the AC photovoltaic effect according to claim 2, wherein The flashing light source module includes a signal generator, a laser driver and a laser. The signal generator is used to output electrical signals with different waveforms, and the laser driver is used to receive the electrical signals and control the laser to output pulsed laser with a target waveform, frequency and intensity.

4. The micro-nano particle characterization system based on the AC photovoltaic effect according to claim 3, wherein An attenuation module is further provided between the laser and the solution of particles to be characterized for attenuating the pulsed laser output by the laser.

5. The micro-nano particle characterization system based on the AC photovoltaic effect according to claim 1, wherein, The ultrathin functional material is tin dioxide, titanium dioxide, zinc oxide, indium tin oxide, aluminum oxide, hafnium oxide, zinc sulfide, zinc selenide, molybdenum disulfide, tungsten disulfide, black phosphorus, graphene, hexagonal boron nitride, methylammonium lead iodide perovskite, methylammonium lead bromide perovskite, methylammonium lead chloride perovskite, methylammonium lead iodide bromide mixed halide perovskite, methylammonium lead iodide chloride mixed halide perovskite, cesium lead bromide perovskite, cesium lead iodide bromide mixed halide perovskite, cesium lead chloride perovskite, lead tin mixed halide perovskite, bismuth silver double halide double perovskite, poly(3-hexylthiophene), poly(3,4-ethylenedioxythiophene) and its sulfonate derivatives, pentacene, anthracene, dibenzoanthracene, fullerene, nickel phthalocyanine, small molecule phthalocyanine, polybenzothiophene, polyfluorene and its copolymers, nickel oxide, copper oxide, gallium nitride, aluminum nitride or MXene; The semiconductor substrate is silicon, gallium arsenide, silicon carbide, indium phosphide, gallium nitride, aluminum nitride, germanium, gallium oxide, zinc oxide, cadmium telluride, silicon germanium alloy, silicon on insulating silicon oxide layer, polyimide film, polyethylene terephthalate film, polycarbonate film, polydimethylsiloxane film or polyvinylidene fluoride film.

6. The micro-nano particle characterization system based on the AC photovoltaic effect according to claim 1, characterized in that, Doping elements are introduced into the ultrathin material for adjusting the electrical and optical properties of the material; the doping elements are metal elements, non-metal elements or rare earth elements; the doping methods adopted are single doping, co-doping or gradient doping, and the doping concentration is 0.001 at% - 20 at%.

7. The micro-nano particle characterization system based on the AC photovoltaic effect according to claim 1, wherein Films, nanowires, arrays or nanorod structures are directly prepared on the semiconductor substrate, and the methods adopted are solution method, self-assembly method, electrochemical method, chemical vapor deposition, physical vapor deposition PVD, template-assisted method, vapor-liquid-solid growth method, chemical etching, printing and coating process or electrospinning process.

8. The micro-nano particle characterization system based on the AC photovoltaic effect according to claim 1, characterized in that, The photoelectric detection module further includes a low-noise preamplifier or a transimpedance amplifier and an oscilloscope. The low-noise preamplifier or the transimpedance amplifier and the oscilloscope are connected to the photodetector for extracting the current signal generated by the scattered light and transmitting it to the signal processing module for analysis.

9. A method for characterizing micro-nano particles based on the AC photovoltaic effect, characterized in that, Characterization is performed using the micro-nano particle characterization system according to claim 1, including the following steps: In an optical dark box, the intermittent optical signal generated by the scintillation light source module is incident on the solution of the particles to be characterized at different angles to generate scattered light; The scattered light is received by a photodetector to generate an alternating current photoelectric signal, and the signal processing module analyzes the alternating current photoelectric signal and outputs the physical parameters of the micro-nano particles.

10. The method for characterizing micro-nano particles based on the AC photovoltaic effect according to claim 9, wherein, The analysis method includes: substituting the varying response currents measured at different angles into the relationship characteristic curve of the response current of the photodetector varying with the light intensity to obtain the absolute value of the scattered light intensity of the particles at different angles and its fluctuation over time; Based on the absolute value of the obtained scattered light intensity and its fluctuation over time, the physical parameters of the micro-nano particles are obtained, and the physical parameters include the diffusion coefficient of the particles, the average particle size and particle size distribution, concentration, zeta potential of the particles, molecular weight, two-dimensional virial coefficient, radius of gyration, and particle shape.

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