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

Abstract

The present invention belongs to the technical field of photoelectric detection, and specifically relates to a micro-nano particle characterization system and method based on an alternating-current photovoltaic effect. The characterization system comprises: a scintillating light source module, which is used for generating intermittent optical signals, wherein the generated intermittent optical signals are directed into a particle solution to be characterized, so as to generate scattered light; a photoelectric detection module, which comprises a photoelectric detector, and is used for receiving the scattered light and generating an alternating-current photoelectric signal, wherein the photoelectric detector comprises 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 a signal processing module, which is used for analyzing the alternating-current photoelectric signal and outputting physical parameters of micro-nano particles. In the present invention, intermittent optical signals are used as incident light, so that the interference of existing continuous laser irradiation on micro-nano particles is effectively reduced; and a photoelectric detector based on an alternating-current photovoltaic effect is used, so that the two major technical problems of the sensitivity being insufficient and the measurement accuracy being insufficient in existing photoelectric detection technology are solved.

Description

Micro-nanoparticle characterization system and characterization method based on alternating current photovoltaic effect TECHNICAL FIELD

[0001] The present application belongs to the technical field of photoelectric detection, and particularly relates to a micro-nanoparticle characterization system and characterization method based on alternating current photovoltaic effect. BACKGROUND

[0002] Photoelectric effect is a basic process of photon and matter interaction, and has wide applications in energy, communication, material science, physics, etc. The research of photoelectric detector promotes the development of optoelectronics, and has a profound influence in the fields of astronomy, optical computing, quantum communication, biomedical science, etc. At the same time, photoelectric effect is applied to material characterization for studying the electronic structure, physical properties and chemical composition of materials, which has wide applications in the fields of material science, biological science, medicine, environmental science, etc.

[0003] Among them, photoelectric detection technology plays a core role in micro-nanoparticle characterization, especially in light scattering technology. After monochromatic light beam irradiates micro-nanoparticles, scattering phenomenon occurs. By measuring the scattered light energy and distribution, the relevant physical properties of the particles are obtained based on Rayleigh scattering theory, Mie scattering theory and Franhofer approximation theory. The performance of the photoelectric detector directly determines the accuracy and range of the above measurements. Traditional photoelectric detection technology mostly relies on photovoltaic effect, and its working principle is to expand the depletion region by applying an external voltage to enhance the photoresponsivity. However, the photoelectric detector in the prior art has the problem of insufficient sensitivity, mainly manifested as large dark current, which makes it difficult to detect extremely weak light signals, resulting in limited measurement range. Although some technologies attempt to work at zero bias voltage to reduce dark current, due to low carrier separation efficiency, the photocurrent output is still greatly limited, and the sensitivity bottleneck has not been broken, which cannot meet the needs of high-precision micro-nanoparticle characterization.

[0004] In addition, in traditional photoelectric detection technology, the measurement of physical properties of micro-nanoparticles usually relies on continuous laser irradiation. However, continuous laser irradiation can cause a series of problems, including temperature rise around the particles, changes in particle physical properties, etc., which can significantly affect the accuracy of the measurement results. Specifically, continuous laser irradiation can cause the following problems:

[0005] Thermal radiation effect: the thermal radiation effect of continuous light field can cause the temperature around the particles to rise, thereby changing the motion state of the particles and affecting the physical properties of the particles. Studies have found that continuous light can cause thermal expansion or chemical reaction changes of the particles, which can cause changes in the morphology and size of the particles, thereby introducing measurement errors. In ultra-high sensitivity physical property characterization, the disturbance of continuous light field to particle physical property characterization cannot be ignored.

[0006] Excitation state interference: when light irradiates the surface of the particle, the energy of the photon is converted into electron excitation, which may cause the rearrangement or release of the surface electrons of the particle, change the chemical composition and surface morphology of the particle, and thus affect the physical properties of the particle. In addition, under the surface plasmon resonance effect, the local electric field and magnetic field generated by the laser on the surface of the particle will further cause a local heating effect, which will disturb the diffusion behavior of the particle and affect the measurement results of the physical properties of the particle.

[0007] Therefore, the sensitivity and measurement accuracy of the existing photoelectric detection technology in micro-nano particle characterization still need to be further improved. SUMMARY

[0008] In order to solve the above technical problems, the present application provides a micro-nano particle characterization system and method based on alternating current photovoltaic effect, which solves the problems of insufficient sensitivity of the existing photoelectric detection technology and interference caused by continuous light field, so as to improve the accuracy and sensitivity of micro-nano particle physical property characterization.

[0009] The present application is realized by the following technical solutions.

[0010] The present application provides a micro-nano particle characterization system based on alternating current photovoltaic effect, comprising:

[0011] The flickering light source module is used to generate intermittent light signals, and the generated intermittent light signals are injected into the solution of the particles to be characterized to generate scattered light.

[0012] The photoelectric detection module comprises a photoelectric detector for receiving scattered light and generating alternating current photoelectric signals; the photoelectric detector comprises a semiconductor substrate and an ultrathin material 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

[0013] The signal processing module is used to analyze the alternating current photoelectric signals and output the physical parameters of the micro-nano particles.

[0014] Among them, the alternating current photovoltaic effect refers to: under the condition of no external bias (0V) or small bias (-0.8V), when the light is periodically irradiated on the nanoscale junction interface of the material, the excess carriers induced by the photons immediately generate and quench in the non-equilibrium state, the electrons oscillate back and forth between the two electrodes, and a large alternating current is generated in the nanoscale junction. Under high switching frequency, the peak value of the alternating current is much higher than that of the direct current (about 2051 times). The alternating current signal does not follow Ohm's law, but conforms to the Maxwell displacement current model.

[0015] Based on the above-mentioned alternating current photovoltaic effect, the application breaks through the sensitivity bottleneck of traditional photoelectric detection technology: the traditional photoelectric detection technology has the limitation of insufficient sensitivity in detecting weak light signals. The application introduces alternating current photovoltaic effect to obtain high alternating current signals under zero bias, avoids the influence of dark current, and enables the detection system of the application to provide ultra-high sensitivity to extremely weak light signals, significantly improve the detection accuracy, especially in the detection of low-concentration micro-nanoparticle scattered light energy, which can achieve higher detection limit and accuracy. According to the pre-experiment results, the detector based on alternating current photovoltaic effect has shown a record-breaking sensitivity (6.09 x 10 9 %), which is more than two orders of magnitude higher than the traditional photoelectric detector in terms of detection ratio (5.4 x 10 14 Jones). This enables the alternating current photovoltaic effect to be applied to the detection of scattered signals of ultra-low concentration micro-nanoparticles, and meets the needs of high-precision and high-sensitivity physical property characterization.

[0016] The application effectively suppresses the negative effects of continuous light field: research shows that laser irradiation has a negative impact on the measurement of the physical properties of micro-nanoparticles, mainly manifested in that the continuous light field causes the particles to deviate from the normal state, resulting in measurement errors. Unlike traditional continuous light irradiation, the application uses flash field to irradiate micro-nanoparticles, fully utilizes the characteristics of alternating current photovoltaic effect, and can effectively reduce the heat radiation, light absorption and excited state changes of particles caused by continuous laser irradiation. Through the use of flash field, micro-nanoparticles can move in a more stable and normal state, thereby ensuring the accuracy of the characterization results of the physical properties of particles and reducing the interference caused by continuous light field.

[0017] Optimization of detection material and structure design: the detector used in the application has a nano-scale structure and fully utilizes the behavior effect of excess carriers in non-equilibrium state in the above-mentioned alternating current photovoltaic effect, which enhances the enhancement effect of alternating current photovoltaic effect. Through this design, the detector can work normally at low voltage (0V) and has self-driving characteristics. This not only greatly reduces the generation of dark current, but also provides strong signal output and significantly improves the sensitivity of the detector. At the same time, the optimization of the device structure also helps to improve the detection efficiency of alternating current photovoltaic effect, providing a higher performance detection platform for the physical property characterization of micro-nanoparticles.

[0018] The application provides a novel physical property characterization technology: the application provides a novel technical means for micro-nanoparticle physical property characterization by in-depth research and verification of the basic physical process and principle of the alternating current photovoltaic effect. Compared with traditional detection methods, the alternating current photovoltaic effect can break through the limitations of traditional technologies, realize higher sensitivity and precision of physical property detection, and is especially suitable for characterization of various physical properties of micro-nanoparticles in complex physical environments. In combination with dynamic light scattering (DLS) and multi-angle light scattering (MALS) technologies, the application can accurately measure physical parameters of micro-nanoparticles, such as diffusion coefficient, particle size distribution, molecular weight, radius of gyration, two-dimensional correlation coefficient, concentration, Zeta potential and the like, and provides a more accurate and comprehensive analysis tool for physical property research of micro-nanoparticles.

[0019] Preferably, the intermittent light signal is a pulsed laser with different waveforms.

[0020] Preferably, the flickering light source module comprises a signal generator, a laser driver and a laser, the signal generator is used to output an electrical signal with different waveforms, the laser driver is used to receive the electrical signal and control the laser to output pulsed laser with target waveforms, frequencies and intensities.

[0021] Preferably, an attenuation module is further arranged between the laser and the solution of the particles to be characterized, for attenuating the pulsed laser output by the laser.

[0022] Preferably, the ultra-thin functional material has a thickness of 0.1-1000 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 photoelectric 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 halide), cesium lead halide perovskite (such as cesium lead bromide, cesium lead iodine 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, dibenzanthracene, fullerene, nickel phthalocyanine, small molecule phthalocyanine, polybenzothiophene, polyfluorene and its copolymer and other small molecule organic dyes; nickel oxide, various copper oxides, gallium nitride, aluminum nitride and MXene.

[0023] 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 insulating silicon oxide layer, and flexible organic substrates such as polyimide film, polyethylene terephthalate film, polycarbonate film, polydimethylsiloxane film, and polyvinylidene fluoride film. Preferably, the ultra-thin functional material is selected from high-stability oxide materials such as tin dioxide, titanium dioxide, aluminum oxide, zirconium oxide, magnesium oxide, hafnium oxide, and other wide-bandgap oxides; or silicon-based semiconductor materials such as silicon nitride and aluminum nitride; and two-dimensional carbon-based materials such as graphene and transition metal sulfides (MoS2, WS2) with excellent stability.

[0024] Preferably, metal, non-metal or rare earth doping elements are introduced into the ultra-thin material to adjust the carrier concentration, mobility, optical absorption and bandgap width, and other electrical and optical properties; the doping elements include, but are not limited to, aluminum, gallium, indium and other metal elements to form aluminum-doped zinc oxide, gallium-doped zinc oxide, and indium-doped zinc oxide; fluorine, nitrogen, sulfur, phosphorus and other non-metallic elements to form fluorine-doped tin dioxide, nitrogen-doped titanium dioxide, sulfur-doped titanium dioxide, and phosphorus-doped titanium dioxide; transition metal elements such as titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, and zinc to further dope tin dioxide, titanium dioxide and other transition metal oxides; rare earth elements such as neodymium, terbium, and cerium to dope rare earth-doped transition metal sulfides; in addition, boron can 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 single doping, co-doping or gradient doping, and the doping concentration is preferably 0.001at% to 20at%.

[0025] The structures such as thin films, nanowires, arrays or nanorods are directly prepared on the semiconductor substrate by using methods including but not limited to solution methods (such as hydrothermal method, hydrothermal assisted sol-gel method, sol-gel method, chemical bath deposition (CBD), immersion 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 / plating), 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 mode 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 techniques (inkjet printing, screen printing, micro-contact printing, drop coating, spray coating) and electrospinning and the like; the nanostructure and thin film preparation methods can be used simultaneously, that is, one or more ways are used to prepare composite nanostructures, and the method for directly preparing structures such as thin films, nanowires, arrays or nanorods on the semiconductor substrate is preferably a hydrothermal method, a vapor deposition method (ALD, MBE, PVD, CVD and the like).

[0026] Preferably, the photoelectric detection module further comprises a low-noise preamplifier or a transimpedance amplifier and an oscilloscope, which are connected with the photoelectric detector, for extracting the current signal generated by the scattered light and transmitting to the signal processing module for analysis.

[0027] The application also provides a micro-nano particle characterization method based on alternating current photovoltaic effect, which is characterized by using the above photoelectric detector device, and comprises the following steps:

[0028] In the optical dark box, the intermittent light signal generated by the flickering light source module is shot into the solution of the particles to be characterized, so as to generate scattered light;

[0029] The photoelectric detection module is used to receive the scattered light and generate alternating current photoelectric signals, and the signal processing module is used to analyze the alternating current photoelectric signals and output the physical parameters of the micro-nano particles.

[0030] Preferably, the analysis method comprises: the intensity change of the scattered light of the particles causes the response current of the photodetector to change accordingly, and the changed response current measured at different angles is substituted into the characteristic curve of the response current of the photodetector changing with the light intensity, so that the absolute value of the light intensity of the particle scattering at different angles and the fluctuation thereof with time can be obtained.

[0031] Based on the obtained absolute value of the scattered light intensity and the fluctuation thereof with time, the physical parameters of the micro-nanoparticles are obtained, including the diffusion coefficient of the particles, the average particle size and particle size distribution, the concentration, the zeta potential of the particles, the molecular weight, the two-dimensional correlation coefficient, the radius of gyration, and the particle shape.

[0032] Compared with the prior art, the present application has the following effects:

[0033] The present application first applies the alternating photovoltaic response effect to micro-nanoparticle characterization, and solves the problems of insufficient sensitivity of the existing photoelectric detection technology and interference caused by continuous light field by utilizing the unique advantages of the alternating photovoltaic effect, so as to improve the accuracy and sensitivity of the micro-nanoparticle physical property characterization, specifically including:

[0034] The flickering light source module is used to generate an intermittent light signal, and the generated intermittent light signal is injected into the solution of the particles to be characterized to generate scattered light; the photoelectric detection module includes a photodetector for receiving the scattered light and generating an alternating photoelectric signal; the photodetector includes a semiconductor substrate and an ultrathin material on the surface of the semiconductor substrate, the ultrathin material is an oxide semiconductor, a nitride semiconductor, a perovskite semiconductor or an organic material semiconductor, and the thickness of the ultrathin material is The signal processing module is used to analyze the alternating photoelectric signal and output the physical parameters of the micro-nanoparticles.

[0035] Through the above device, under the condition of no external bias (0V) or small bias (-0.8V) and periodic light, the photonic-induced non-equilibrium excess carriers oscillate back and forth between the two electrodes, generating extremely high alternating current signals, and significantly improving the sensitivity of the photodetector. Experimental results show that compared with the traditional photoelectric detection technology, the sensitivity of the present application is improved by two orders of magnitude, and the ultra-high sensitivity micro-nanoparticle physical property characterization can be realized under extremely weak light conditions. This breakthrough not only widens the application range of photoelectric detection technology, but also significantly improves the limit of concentration detection, providing a more accurate technical means for micro-nanoparticle characterization.

[0036] Unlike the traditional continuous laser irradiation, the present application adopts an intermittent light mode, which significantly reduces the thermal radiation effect and excited state interference of continuous light on micro-nanoparticles. Experiments have proved that this method can provide more accurate micro-nanoparticle physical property characterization results, significantly reducing the measurement error, and providing reliable technical support for high-precision micro-nanoparticle characterization.

[0037] The present application solves two technical problems of the prior art photoelectric detection technology in sensitivity and measurement accuracy by innovatively introducing the alternating current photovoltaic effect: significantly improves the sensitivity of the photoelectric detector, breaks through the sensitivity bottleneck of the traditional technology; effectively reduces the interference of continuous laser irradiation on the micro-nanoparticles, and improves the measurement accuracy. These technical breakthroughs not only broaden the application range of photoelectric detection technology, but also provide more accurate and reliable technical means for micro-nanoparticle characterization, which has important scientific significance and application value. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is a schematic diagram of a micro-nanoparticle characterization system based on alternating current photovoltaic effect.

[0039] Figure 2 is a relationship between the light scattering technology and the characterization parameters involved in the present application.

[0040] Figure 3 is a schematic diagram of the improvement idea of the micro-nanoparticle characterization system based on alternating current photovoltaic effect of the present application.

[0041] Figure 4 is a graph of the change of the device response current with the concentration of anatase TiO2 particle dispersion liquid with an average particle size of 100 nm.

[0042] Figure 5 is a graph of the relationship between the response current and particles of different average sizes. DETAILED DESCRIPTION

[0043] In order for those skilled in the art to better understand the technical solutions of the present application and to implement them, the present application will be further described below in conjunction with specific embodiments and drawings, but the embodiments are not limiting of the present application. The experimental methods and detection methods described in the following embodiments are all conventional methods unless otherwise specified; the reagents and materials described are all commercially available unless otherwise specified.

[0044] The present application provides a micro-nanoparticle characterization system based on alternating current photovoltaic effect, as shown in Figure 1, which comprises

[0045] A flickering light source module for generating intermittent light signals, the generated intermittent light signals are injected into the solution 4 of the particles to be characterized to generate scattered light 10. The angle is 13°-173°, preferably 90°.

[0046] A photoelectric detection module for receiving scattered light 10 and generating alternating current photoelectric signals.

[0047] A signal processing module 7 for analyzing alternating current photoelectric signals and outputting physical parameters of micro-nanoparticles. The signal processing module 7 is a computer.

[0048] Preferably, the intermittent light signal is a pulsed laser with different waveforms. It can be a sine wave, a square wave or a triangular wave.

[0049] The scintillation light source module comprises a signal generator 1, a laser driver 2 and a laser 3, the signal generator 1 is used to output electrical signals of different waveforms, the laser driver 2 is used to receive the electrical signals and control the laser 3 to output pulsed laser of target waveform, frequency and intensity. The laser driver 2 plays a bridge role, converts the electrical signals of the signal generator 1 into current signals to drive the laser, and ensures that the laser outputs corresponding optical signals according to the target waveform. The frequency range is 0.01Hz-100GHz, and the intensity range is 1pW-50W.

[0050] Preferably, an attenuation module 8, specifically a neutral density attenuation sheet, is further arranged between the laser 3 and the solution 4 of particles to be characterized, for attenuating the pulsed laser output by the laser. The solution 4 of particles to be characterized is further provided with a beam stopper 9 on the other side away from the attenuation module 8.

[0051] Preferably, the photoelectric detection module comprises a photoelectric detector 5, the photoelectric detector 5 comprises a semiconductor substrate and an ultrathin material on the surface of the semiconductor substrate, and the ultrathin material is an oxide semiconductor, a nitride semiconductor or an organic material semiconductor.

[0052] Preferably, the ultrathin functional material has a thickness of 0.1-1000nm. 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-insulating silicon oxide layer, and flexible organic substrates such as polyimide film, polyethylene terephthalate film, polycarbonate film, polydimethylsiloxane film and polyvinylidene fluoride film, etc.

[0053] Preferably, metal, non-metal or rare earth doping elements are introduced into the ultra-thin functional material to adjust the electrical and optical properties such as carrier concentration, mobility, optical absorption and band gap width; the doping elements include but are not limited to: doping with aluminum, gallium, indium and other metal elements to form aluminum-doped zinc oxide, gallium-doped zinc oxide, indium-doped zinc oxide; doping with fluorine, nitrogen, sulfur, phosphorus and other non-metal elements to form fluorine-doped tin dioxide, nitrogen-doped titanium dioxide, sulfur-doped titanium dioxide, phosphorus-doped titanium dioxide; further doping tin dioxide, titanium dioxide and other transition metal oxides with transition metal elements such as titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper and zinc; doping with neodymium, terbium, cerium and other rare earth elements to prepare rare earth-doped transition metal sulfides; 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 single doping, co-doping or gradient doping, and the doping concentration is preferably 0.001at% to 20at%.

[0054] The structure of thin film, nanowire, array or nanorod is directly prepared on the semiconductor substrate, and the method includes but is not limited to solution method (such as hydrothermal method, hydrothermal assisted sol-gel method, sol-gel method, chemical bath deposition (CBD), immersion method, spin coating method), self-assembly method (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 method (such as electrochemical deposition / plating), vapor deposition method (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 mode 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 method (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 technology (inkjet printing, screen printing, micro-contact printing, drop coating, spray coating) and electrospinning and the like.

[0055] Preferably, the photodetector 5 is connected with a low-noise preamplifier or a resistance amplifier and an oscilloscope 6, which is used to extract the current signal generated by the scattered light and transmit the signal to a signal processing module 7 for processing and analysis.

[0056] The application also provides a micro-nano particle characterization method based on alternating current photovoltaic effect, which is characterized by using the above photodetector device, and includes the following steps:

[0057] In the optical dark box (the part shown by the dotted line in FIG. 1), the intermittent light signal generated by the flickering light source module is injected into the solution of the particles to be characterized to generate scattered light.

[0058] The scattered light is received by the photoelectric detection module to generate an alternating current photoelectric signal, and the signal processing module is used to analyze the alternating current photoelectric signal and output the physical parameters of the micro-nanoparticles.

[0059] Preferably, the analysis method comprises: 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, thereby providing data support for further calculation of the physical characteristics of the particles. Combined with the principles of dynamic light scattering (DLS), static light scattering (SLS) and multi-angle light scattering (MALS) technology, the diffusion coefficient, average particle size and particle size distribution and concentration of the particles can be calculated in detail. At the same time, referring to the principle of electrophoretic light scattering (ELS), electrode plates can be added on both sides of the cuvette, so that the zeta potential of the particles can be calculated by using electrophoretic light scattering technology. The core advantage of this technology is to realize accurate detection of the interaction between micro-nanoparticles and flickering pulsed laser through the ultra-high sensitivity of the alternating current photovoltaic effect, thereby establishing an accurate relationship between the detection signal and the physical characteristics of the particles. This method not only has extremely high sensitivity, but also can realize high-precision physical property characterization in low-concentration particle samples, and is particularly suitable for complex physical environments and simultaneous detection of multiple physical parameters.

[0060] The physical parameters that can be characterized by the present application include the diffusion coefficient, average particle size and particle size distribution, concentration, zeta potential of the particles, molecular weight, two-dimensional correlation 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 application have a wide range of applications and can provide a multi-parameter and all-round physical property characterization tool for the study of micro-nanoparticles. FIG. 2 further illustrates the light scattering technology involved in the present application and its relationship with the physical parameters. Through the quantitative relationship between the scattered light intensity of the micro-nanoparticles and various physical characteristics, the present application can accurately analyze the behavior of the particles in the light field and provide high-precision quantitative analysis of their physical characteristics. Compared with traditional photoelectric detection technology, although the basic light scattering principle and formula have not changed, the innovation of the present application lies in the combination of the flash field and the alternating current photovoltaic effect, which makes the technology show great advantages in sensitivity and anti-interference ability.

[0061] The detection system of the present application can obtain multiple physical parameters of particles, such as particle size distribution, shape, concentration, and hydrodynamic radius, by adjusting the analysis mode of the detection signal. These parameters not only have important significance for the basic research of micro-nanoparticles, but also can be widely applied in the fields of nanomaterials, nanomedicine, environmental monitoring, etc. Due to the close relationship between the detection signal and the multiple physical characteristics of micro-nanoparticles, the present application can not only provide high-precision characterization of the physical characteristics of micro-nanoparticles, but also adapt to the needs of different particle systems and different experimental environments, and has great practical potential and popularization value.

[0062] It should be noted that, as shown in FIG. 3, the present application uses a flash pulse laser and a photodetector based on the alternating current photovoltaic effect to characterize the physical properties of micro-nanoparticles. The core testing principle is to combine the scattering of flash laser by micro-nanoparticles and the characteristics of alternating current photovoltaic effect, and to detect the relationship between scattered light intensity and current fluctuation to deduce the physical parameters of the particles. Through this principle, the present application can realize high-precision, multi-parameter characterization of micro-nanoparticles. The key point is that:

[0063] Application of new physical effect: the alternating current photovoltaic effect is applied to micro-nanoparticle characterization for the first time, and the alternating current photoelectric signal generated during the on-off of light is used to realize ultra-high sensitivity detection.

[0064] It should be noted that the alternating current photovoltaic effect is:

[0065] Under the condition of no external bias (0V), when the light is periodically irradiated on the nanoscale junction interface of the material, the excess carriers induced by the photons immediately generate and quench in the non-equilibrium state, the electrons oscillate back and forth between the two electrodes, and a large alternating current is generated in the nanoscale junction. Under high switching frequency, the peak value of the alternating current is much higher than that of the direct current (about 2051 times). The alternating current signal does not follow Ohm's law, but conforms to the Maxwell displacement current model. Under periodic light irradiation, the non-equilibrium excess carriers induced by the photons oscillate back and forth between the two electrodes, generating a very 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 of the material interface, the charge distribution is unbalanced, and the electrons flow in the external circuit to establish a new balance to balance the potential difference between the electrodes.

[0066] Material innovation: ultra-thin film material (thickness of 100 nm) is used ) and currently preferred are titanium dioxide (TiO2) and tin dioxide (SnO2), and other oxides, nitrides, perovskites and organic materials can be used. The nanoscale junction structure of this material design can significantly enhance the performance of the alternating current photovoltaic effect. Nanoscale structure materials can provide higher surface area and more non-equilibrium carriers, thereby promoting the generation of alternating current photovoltaic effect. The selection of this material structure enables the device to have higher response capability when detecting weak signals, and can effectively characterize the physical properties of extremely small particles.

[0067] Light source design: using scintillation light as the light source, alternating current photovoltaic signals are generated by the instantaneous on and off of the light, avoiding the thermal radiation effect and excited state interference caused by continuous laser irradiation.

[0068] Self-driving characteristics: no external voltage or weak voltage (<0.8V) needs to be applied

[0069] By scattering the scintillation light with micro-nano particles, the alternating current photovoltaic effect is used to realize scattered light detection.

[0070] The present application uses alternating current photovoltaic effect light detection technology, which brings significant improvement in all aspects, including:

[0071] Improved detection performance: the present application uses alternating current photovoltaic effect as the core detection principle, which has the greatest advantage over traditional photodetector technology in terms of ultra-high sensitivity to light. The alternating current photovoltaic effect can produce a strong response under extremely weak light signals, so that the present application can be used for high-precision detection of low-concentration target substances. This ultra-high sensitivity of light response greatly improves the detection limit, and is particularly suitable for the detection and physical property characterization of low-concentration micro-nano particles, effectively improving the shortcomings of traditional technology in this regard. In addition, since the present application uses ultra-thin materials (polycrystalline, single crystal, amorphous) instead of high-temperature prepared single crystal materials, the preparation cost of the present application is significantly reduced, and the material selection is widely, further reducing the material cost.

[0072] Low cost: the photodetector of the present application uses ultra-thin materials, avoiding the high-temperature preparation process required by traditional single crystal materials, greatly reducing the preparation cost. Ultra-thin materials not only have low price, but also have wide material selection range, including but not limited to oxide materials such as titanium dioxide (TiO2) and tin dioxide (SnO2), nitrides, perovskite materials and organic materials. This low-cost material selection and preparation process makes the present application have significant economic advantages, suitable for large-scale production and application.

[0073] Low energy consumption: The photoelectric detector of the present application has a self-driving feature and does not require external bias to work. Unlike traditional photoelectric detectors that require an external bias, the device of the present application can work under the condition of 0V. The advantage of this feature is that it can provide strong signal output without increasing additional energy consumption, while maintaining extremely low dark current. This makes the system operation more simple, can be widely used in different experimental environments, and reduces the complexity and energy consumption of traditional photoelectric detectors in use. In addition, since no external voltage is required for driving, the energy consumption of the present application is significantly reduced, further improving its economic and environmental performance in practical applications.

[0074] The application of flash field reduces the negative effects of continuous light field: The present application innovatively uses flash field as the laser irradiation source, which can effectively reduce the heat radiation, light absorption and particle state changes caused by excited state of laser on micro-nano particles compared with traditional continuous light method. Studies have shown that continuous light field may cause micro-nano particles to deviate from the normal state, thereby affecting the accuracy of physical property measurement. By using flash field, micro-nano particles can maintain a relatively stable state when receiving short pulse laser, thereby 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, further reducing the overall energy consumption of the system.

[0075] Lower concentration detection limit and higher concentration resolution: Due to the ultra-high sensitivity of alternating photovoltaic effect, the present application can break through the detection limit of traditional technology and realize the detection of micro-nano particles at extremely low concentration. By improving the resolution of the detector, the present application can more accurately distinguish different concentrations of target substances, with higher concentration resolution. This advantage enables the present application to provide higher measurement accuracy and signal-to-noise ratio in the measurement of micro-nano particles, especially in the case of low concentration and weak signal. At the same time, due to the use of low-cost materials and low-energy consumption design, the present application realizes high-precision detection while maintaining low economic cost and energy consumption.

[0076] Advantages and application prospects: The present application introduces alternating photovoltaic effect, new self-made device and the application of flash field, which not only improves the sensitivity and accuracy of micro-nano particle characterization, but also significantly improves the limitations of traditional photoelectric detection technology, providing a new technical means for high-precision, multi-parameter physical property characterization of micro-nano particles. These significant effects make the present application have wide application prospects in nanotechnology, physical and chemical research and related fields. In addition, the low-cost and low-energy consumption characteristics of the present application make it have great market potential in industrial detection, environmental monitoring, biomedicine and other fields, which can meet the needs of large-scale applications.

[0077] In order to further illustrate the present application, the following tests are carried out:

[0078] (1) Detection of low concentration micro-nanoparticles

[0079] The detection of low concentration micro-nanoparticles is carried out by using a photodetector based on the alternating current photovoltaic effect.

[0080] Step 1: Square wave pulsed laser is irradiated at 90° to the micro-nanoparticles suspended in the solution (in an optical dark box) by adjusting the laser pulse frequency (200 Hz) and intensity (32.4 mW).

[0081] Step 2: The scattered light is received by the photodetector to obtain the current value, the scattered light intensity signal is measured, and the data is analyzed, and the results are shown in Figure 4. The photodetector includes a P-type silicon substrate, a 15 nm TiO2 film is deposited on the P-type silicon substrate as an active layer, and then ITO and aluminum electrodes are deposited on the surface of the TiO2 and the back of the P-type silicon substrate, respectively. Figure 4 shows the change of the response current of the device with the concentration of the 100 nm average particle size anatase TiO2 particle dispersion. The results show that the detector of the present application can successfully extract the scattering signal of the particles at such a low concentration, and the detection accuracy is greatly improved, and the sensitivity is greatly improved compared with the traditional photodetector. This experiment verifies the superiority of the present application in the detection of low concentration micro-nanoparticles, and shows high detection sensitivity and accuracy.

[0082] Another important feature of the present application is the self-driving feature of the photodetector, i.e. it can work normally without external bias (or with a small external bias). Compared with the traditional photodetector which needs an external power supply to provide a bias, the self-driving feature of the present application does not need an external power supply, avoids the negative impact of the external power supply on increasing the dark current, greatly simplifies the operation process, and improves the adaptability and reliability under complex experimental conditions.

[0083] (2) Different particle size characterization: The photodetector in (1) is used to test anatase TiO2 dispersions with different average particle sizes (all with a concentration of 10 -3 g / L). Square wave pulsed laser (200 Hz, 32.4 mW) is vertically incident at 90° to each particle size sample, the device response current is recorded, and the corresponding scattered light intensity average value is calculated. The experimental results are shown in Figure 5, and the response currents of different particle size samples are significantly different, and the particle size can be accurately mapped by the scattered light intensity, and the different average particle size TiO2 particles can be clearly distinguished. This experiment further proves the high sensitivity and high accuracy of the present application in particle size characterization.

[0084] Through the verification of multiple test examples, the micro-nanoparticle characterization method based on alternating current photovoltaic effect of the application shows ultra-high sensitivity, accurate detection ability and good adaptability in the detection of particles with different concentrations, sizes, types and crystal forms. These experimental results fully prove the wide application prospect and implementability of the application.

[0085] Obviously, those skilled in the art can make various modifications and variations to the application without departing from the spirit and scope of the application. Thus, if these modifications and variations of the application fall within the scope of the claims of the application and their equivalent technologies, these modifications and variations are also intended to be included.

Claims

1. A micro- and nano-particle characterization system based on alternating current photovoltaic effect, characterized by, The system comprises: a flickering light source module for generating intermittent light signals, which are projected into a solution of particles to be characterized to generate scattered light; a photodetection module comprising a photodetector for receiving the scattered light and generating an alternating current photoelectric signal; The photoelectric detector comprises a semiconductor substrate and an ultrathin material on the surface of the semiconductor substrate, the ultrathin material is an oxide semiconductor, a nitride semiconductor or an organic material semiconductor, the thickness of the ultrathin material is a signal processing module for analyzing the alternating current photoelectric signal and outputting physical parameters of the micro-nano particles.

2. The micro- and nano-particle characterization system based on alternating current photovoltaic effect according to claim 1, wherein, The intermittent light signals are pulsed laser beams with different waveforms.

3. The micro- and nano-particle characterization system based on alternating current photovoltaic effect according to claim 2, wherein, The flickering light source module comprises a signal generator for outputting electrical signals with different waveforms, a laser driver for receiving the electrical signals and controlling the laser to output pulsed laser beams with target waveforms, frequencies and intensities.

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

5. The micro- and nano-particle characterization system based on alternating current photovoltaic effect according to claim 1, wherein, The ultra-thin 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 iodine perovskite, methylammonium lead bromide perovskite, methylammonium lead chloride perovskite, methylammonium lead iodine bromide mixed halide perovskite, methylammonium lead iodine chloride mixed halide perovskite, cesium lead bromide perovskite, cesium lead iodine 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, dibenzanthracene, fullerene, nickel phthalocyanine, small molecule phthalocyanine, polybenzothiophene, polyfluorene and its copolymer, 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- and nano-particle characterization system based on alternating current photovoltaic effect according to claim 1, wherein, Doping elements are introduced into the ultra-thin 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 are single doping, co-doping or gradient doping, and the doping concentration is 0.001at% to 20at%.

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

8. The micro- and nano-particle characterization system based on alternating current photovoltaic effect according to claim 1, wherein, The photodetection module further comprises a low-noise preamplifier or a transimpedance amplifier and an oscilloscope, which 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- and nano-particles based on alternating current photovoltaic effect, characterized in that, The micro-nano particle characterization system of claim 1 is used for characterization, comprising the following steps: In an optical dark box, the intermittent light signals generated by the flickering light source module are projected into a solution of particles to be characterized at different angles to generate scattered light; In an optical dark box, the intermittent light signals generated by the flickering light source module are projected into a solution of particles to be characterized at different angles to generate scattered light; The scattered light is received by a photoelectric detector to 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-nanoparticles.

10. The micro- and nanoparticle characterization method based on alternating current photovoltaic effect according to claim 9, characterized in that, The analysis method comprises: substituting the measured varying response currents at different angles into a characteristic curve of the response current of the photoelectric detector varying with the light intensity to obtain absolute values of the light intensity of the particle scattering at different angles and fluctuations of the absolute values with time; Based on the obtained absolute values of the light intensity of the scattering and the fluctuations of the absolute values with time, physical parameters of the micro-nanoparticles are obtained, and the physical parameters include a diffusion coefficient of the particles, average particle size and particle size distribution, concentration, zeta potential of the particles, molecular weight, two-dimensional correlation coefficient, radius of gyration and particle shape.

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