Nanoscale variable-temperature infrared absorbance in-situ characterization device

Abstract

The invention provides a nanoscale variable-temperature infrared absorbance in-situ characterization device. The nanoscale variable-temperature infrared absorbance in-situ characterization device comprises an in-situ heating module, a variable-temperature infrared excitation module and a variable-temperature infrared detection module, the in-situ heating module comprises a heating body, an AFM conductive probe and a probe micro-cantilever capable of conducting heat, one end of the probe micro-cantilever is connected with the AFM conductive probe, the other end of the probe micro-cantilever is in thermal contact with the heating body, and the AFM conductive probe is in contact with a to-be-detected area of a to-be-detected sample so as to realize in-situ heating of the to-be-detected area; the variable-temperature infrared excitation module is used for transmitting pulse infrared laser to an area to be detected and is electrically connected with the variable-temperature infrared detection module to transmit laser information of the pulse infrared laser; wherein the in-situ heating to-be-detected area generates local photo-thermal expansion vibration under the action of the pulse infrared laser and drives the probe micro-cantilever to vibrate at the same frequency; the variable-temperature infrared detection module completes nanoscale variable-temperature infrared absorbance analysis of the to-be-detected area based on vibration and laser information of the probe micro-cantilever.

Description

Technical Field

[0001] The invention relates to a nanometer-scale variable temperature infrared absorbance in-situ characterization device, belonging to the field of signal detection instruments. Background Art

[0002] Traditional Fourier transform infrared spectroscopy is an important chemical analysis method for analyzing the phase composition and chemical functional group structure of materials, and has important applications in materials, chemistry, biology, and medicine. However, the spatial resolution of traditional Fourier transform infrared spectroscopy is limited to the micrometer scale, and it is unable to achieve nanoscale infrared absorbance analysis, thus failing to meet the urgent need for the rapid development of nanomaterial scientific characterization. Although commercialized nano-infrared photothermal microscopy can achieve nanoscale infrared absorbance analysis by in-situ detection of nanoscale infrared photothermal expansion signals, it cannot achieve nanoscale variable temperature infrared absorbance analysis, which greatly limits the structural evolution behavior of nanoscale phases and chemical functional groups in materials science in response to temperature.

[0003] Therefore, in response to the urgent need for in-situ characterization of nanochemistry in materials science, there is an urgent need to provide a nanoscale variable temperature infrared absorbance in-situ characterization device, so as to realize the acquisition and chemical imaging of variable temperature infrared spectra of material phases and chemical functional groups at the nanoscale, so as to promote the innovative development and in-depth application of materials science and nano-characterization technology. Summary of the invention

[0004] In response to the current urgent need for nanoscale infrared absorbance characterization, the present invention develops a device based on an atomic force microscope (AFM) platform that can achieve high-resolution microscopic characterization of nanoscale infrared absorbance, so as to promote innovative research on in-situ characterization of the nanoscale chemical composition and structure of related materials.

[0005] More specifically, the present invention develops a nanoscale variable temperature infrared absorbance in-situ characterization device based on the AFM nanoplatform to realize the collection and chemical imaging of infrared spectra of material phases and chemical functional groups at the nanoscale under different temperature conditions, providing a nano-characterization device with simple principles and direct tests for the analysis of the nanoscale chemical composition and structure of materials.

[0006] The present invention provides a nanoscale variable temperature infrared absorbance in-situ characterization device, comprising an in-situ heating module, a variable temperature infrared excitation module and a variable temperature infrared detection module; The in-situ heating module comprises a heating element, an AFM conductive probe and a heat-conducting probe micro-cantilever, one end of the probe micro-cantilever is in thermal contact with the heating element, and the other end is connected to the AFM conductive probe to transfer the heat energy of the heating element to the AFM conductive probe, and the AFM conductive probe is in contact with a test area of ​​the sample to be tested to achieve in-situ heating of the test area; The variable-temperature infrared excitation module is used to emit pulsed infrared laser to the area to be measured, and is electrically connected to the variable-temperature infrared detection module to send the laser information of the pulsed infrared laser; wherein The area to be measured with in-situ heating generates local optothermal expansion vibration under the action of the pulsed infrared laser, and drives the probe microcantilever to vibrate at the same frequency; The variable-temperature infrared detection module is used to obtain the vibration information of the probe microcantilever, and obtain the local optothermal expansion vibration information at least based on the vibration information and the laser information, so as to realize the nano-scale variable-temperature infrared absorbance analysis of the area to be measured.

[0007] Optionally, in some embodiments of the present invention, the variable-temperature infrared detection module includes an AFM laser, an AFM four-quadrant photodetector and a data processing and display platform. The data processing and display platform is electrically connected to the AFM four-quadrant photodetector and the variable-temperature infrared excitation module, wherein The AFM laser is used to send an AFM incident laser beam to the probe microcantilever, and the AFM four-quadrant photodetector is used to receive the AFM reflected laser beam refracted from the probe microcantilever and send it to the data processing and display platform in the form of an electrical signal; The data processing and display platform completes the nano-scale variable-temperature infrared absorbance analysis of the area to be measured based on the electrical signal sent by the AFM four-quadrant photodetector and the laser information sent by the variable-temperature infrared excitation module.

[0008] Optionally, in some embodiments of the present invention, the variable-temperature infrared detection module further includes a lock-in amplifier, and the lock-in amplifier is electrically connected to the AFM four-quadrant photodetector and the data processing and display platform. Among them, The lock-in amplifier is used to perform Fourier transform on the electrical signal sent by the AFM four-quadrant photodetector and send it to the data processing and display platform to realize the conversion of the time-domain signal into the frequency-domain signal.

[0009] Optionally, in some embodiments of the present invention, the contact position of the AFM incident laser beam and the probe microcantilever is set on the side facing away from the AFM probe bracket and at the position corresponding to the AFM probe bracket.

[0010] Optionally, in some embodiments of the present invention, the variable-temperature infrared detection module includes an AFM sample stage, an AFM scanner and an AFM control system. The sample to be measured is arranged on the AFM sample stage, and the AFM scanner is fixedly connected to the AFM sample stage, wherein The AFM control system is used to control the three-dimensional movement of the AFM scanner to realize the high-precision positioning and area scanning of the area to be measured of the sample to be measured.

[0011] Optionally, in some embodiments of the present invention, the in-situ heating module further includes an excitation source for providing a heating voltage to the heating element to selectively adjust the thermal energy emitted by the heating element, where The heating element is composed of a thermistor wrapped by an insulating layer, and the thermistor is electrically connected to the excitation source for efficient heat transfer without conduction.

[0012] Optionally, in some embodiments of the present invention, the in-situ heating module further includes an insulating base made of a heat-conducting material. One side of the insulating base is connected to the heating element, and the other side is connected to the probe microcantilever, where The insulating base is used to transfer the heat of the heating element to the probe microcantilever while preventing electrical contact between the heating element and the probe microcantilever.

[0013] Optionally, in some embodiments of the present invention, the in-situ heating module further includes a temperature controller and a thermocouple made of a heat-conducting material. The thermocouple is in thermal contact with the heating element and connected to the temperature controller. The temperature controller indirectly obtains the tip heating temperature of the AFM conductive probe based on the temperature of the thermocouple.

[0014] Optionally, in some embodiments of the present invention, the AFM conductive probe is slightly in contact with the sample to be measured, such that the contact area between the AFM conductive probe and the sample to be measured is 10 - 30 nm, and the typical value of the acting force is 1 nN to 30 nN.

[0015] Optionally, in some embodiments of the present invention, the variable-temperature infrared excitation module includes a pulsed laser control system, a mid-infrared laser, and an infrared optical path control system, where The pulsed laser control system is electrically connected to the mid-infrared laser to control the mid-infrared laser to emit the pulsed infrared laser and is electrically connected to the variable-temperature infrared detection module to send the laser information of the pulsed infrared laser; The infrared optical path control system is used to focus the pulsed infrared laser on the area to be measured to in-situ excite the nano-scale variable-temperature photothermal expansion signal in the in-situ heated area to be measured.

[0016] Optionally, in some embodiments of the present invention, the nano-scale variable-temperature infrared absorbance analysis of the area to be measured at least includes the fixed-point nano-scale variable-temperature infrared spectroscopy analysis of the sample material and the variable-temperature nano-chemical microscopy analysis of the scanned area.

[0017] The beneficial effects of the present invention are as follows: The object of the present invention is to provide a nano-scale in-situ characterization device for variable-temperature infrared absorbance. This device combines the photo-thermal expansion effect of the interaction between pulsed mid-infrared and sample materials, the infrared absorption of sample materials, the nano-scale inspection of an atomic force microscope probe, and the Fourier transform of the periodic signal of the periodic signal, establishing an in-situ high-resolution characterization device for nano-scale variable-temperature infrared absorbance based on an atomic force microscope, realizing the in-situ acquisition of nano-scale infrared spectra and high-resolution chemical imaging of sample materials under variable-temperature conditions. It has the advantages of ultra-high resolution at the nano-scale, high sensitivity, high signal-to-noise ratio, and direct testing.

[0018] The key technical device described in the present invention has a simple structure and strong compatibility, and is suitable for combination with different commercial AFM control systems. It is a new technology that is easy to promote and apply, providing an important in-situ nano-characterization device for the in-depth development of related AFM technologies and the study of variable-temperature infrared absorbance closely related to the chemical structure of materials. Brief Description of the Drawings

[0019] Embodiments of the present disclosure will now be described in detail with reference to the drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts. In addition, although the terms used in the present disclosure are selected from well-known and commonly used terms, some of the terms mentioned in the specification of the present disclosure may be selected by the inventor according to his or her judgment, and their detailed meanings are described in the relevant parts of the description herein. In addition, it is required to understand the present disclosure not only through the actual terms used, but also through the meaning implied by each term.

[0020] Below, with reference to the drawings, for those skilled in the art of this technology, from the detailed description of the present invention, the above and other objects, features, and advantages of the present invention will be obvious.

[0021] Figure 1 Schematically shows the overall schematic diagram of the nano-scale in-situ characterization device for variable-temperature infrared absorbance of the present invention; Figure 2 Schematically shows the structural block diagram of the nano-scale in-situ characterization device for variable-temperature infrared absorbance of the present invention; Figure 3 Schematically shows the relationship between the probe heating voltage and the probe heating temperature; Figure 4 Schematically shows the nano-infrared spectrum characterization results of the perovskite methylammonium lead iodide crystal sample material at different heating temperatures; Figure 5 Schematically shows the nano-chemical microscopy image results of the perovskite methylammonium lead iodide crystal sample material at different heating temperatures; Figure 6Shows the nano-scale chemical micrographs of another scanned area of the perovskite methylammonium lead iodide crystal sample material at a heating temperature of 34.7 °C and different times. Reference numerals

[0022] 100, nano-scale in-situ heating module; 1, AFM conductive probe; 2, probe microcantilever; 3, AFM conductive probe holder; 4, insulating base; 5, heating element; 6, thermocouple; 7, thermocouple temperature controller; 8, excitation source; 200, nano-scale variable-temperature infrared absorbance excitation module; 9, pulsed laser control system; 10, mid-infrared laser; 11, infrared optical path control system; 12, pulsed infrared laser; 13, sample material; 300, nano-scale variable-temperature infrared absorbance detection module; 14, AFM sample stage; 15, AFM scanner; 16, AFM laser; 17, AFM incident laser beam; 18, AFM reflected laser beam; 19, AFM photoelectric quadrant detector; 20, microcantilever deformation signal terminal; 21, lock-in amplifier; 22, AFM control system; 23, data processing and display platform. Detailed implementation manners

[0023] The present invention will be further described below through the following implementation manners. It should be understood that the following implementation manners are only used to illustrate the present invention and do not limit the present invention.

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some examples or embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, the present invention can also be applied to other similar scenarios based on these drawings. Unless obvious from the language context or otherwise stated, the same reference numerals in the figures represent the same structure or operation.

[0025] In the description of the present invention, it should be understood that the orientation terms such as "front, back, up, down, left, right", "horizontal, vertical, perpendicular, horizontal" and "top, bottom" usually indicate the orientation or position relationship based on the orientation or position relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description. Without contrary description, these orientation terms do not indicate and imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the protection scope of the present invention; the orientation terms "inside, outside" refer to the inside and outside relative to the contour of each component itself.

[0026] For ease of description, spatial relative terms, such as "above", "over", "on the upper surface", "upper", etc., may be used herein to describe the spatial positional relationship of one device or feature to other devices or features as shown in the figures. It should be understood that the spatial relative terms are intended to encompass different orientations in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, a device described as "above" or "over" other devices or structures will then be positioned "below" or "beneath" the other devices or structures. Thus, the exemplary term "above" can include both orientations of "above" and "below". The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and corresponding interpretations of the spatial relative descriptions used herein will be made.

[0027] The following examples are all the characterization results of materials by the device of the nano-thermal infrared microscopy of the present invention to further illustrate the effects of the present invention, but are not limited to the following embodiments.

[0028] The present invention provides a nano-scale variable-temperature infrared absorbance in-situ characterization device, and its composition principle structure is as Figure 1 shown. The device includes three components: an in-situ heating module (nano-scale in-situ heating module 100), a variable-temperature infrared excitation module (nano-scale variable-temperature infrared absorbance excitation module 200), and a variable-temperature infrared detection module (nano-scale variable-temperature infrared absorbance detection module 300).

[0029] Its working principle can be specifically described as follows: The nano-scale in-situ heating module 100 is used to heat the AFM conductive probe 1, so that the tip of the AFM conductive probe 1 is heated, thereby realizing in-situ heating of the tip-sample nano-scale contact area; the nano-scale variable-temperature infrared absorbance excitation module 200 is used to in-situ excite pulsed mid-infrared laser, and at the same time realize the control of the pulsed infrared laser 12 emitted by the mid-infrared laser 10, so that the pulsed infrared laser 12 is focused on the tip-sample nano-scale contact area.

[0030] Under the combined action of the in-situ heating module 100 at the nanoscale and the variable-temperature infrared absorbance excitation module 200 at the nanoscale, the area to be measured of the sample material 13 is in-situ excited with a nanoscale photothermal expansion effect signal under the action of in-situ heating and the pulsed infrared laser 12. Since this signal is directly closely related to the infrared absorbance of the nanoscale structure of the sample, the infrared absorbance of the nanoscale structure of the sample material 13 can be detected by detecting the nanoscale photothermal expansion effect signal of the area to be measured of the sample material 13. The variable-temperature nanoscale infrared absorbance in-situ acquisition module 300 is used to in-situ detect and process the variable-temperature nanophotothermal expansion effect vibration signals at continuous wave numbers and the variable-temperature nanophotothermal expansion effect vibration signals of each pixel point in the area of the surface scan at a single wave number, so that the variable-temperature nanoscale infrared spectrum and the nanoscale chemical microscopy imaging can be obtained respectively.

[0031] Based on this working principle, the present invention has established a variable-temperature nanoscale infrared absorbance in-situ characterization device to realize the characterization of the infrared absorbance at the nanoscale of the material sample 13, and its working structure is as Figure 1-2 shown.

[0032] Specifically, the in-situ heating module 100 at the nanoscale includes: an AFM conductive probe 1, a probe microcantilever 2, an AFM conductive probe holder 3, an electrically insulating base 4, a heating element 5, a thermocouple 6, a thermocouple temperature controller 7, and an excitation source 8. The heating element 5, the electrically insulating base 4, the probe microcantilever 2, the AFM conductive probe 1, and the AFM conductive probe holder 3 are connected in sequence from top to bottom.

[0033] Specifically, the probe microcantilever 2 is made of a heat-conducting material. One end of the probe microcantilever 2 is connected to the AFM conductive probe 1, and the other end is connected to the insulating base 4 and the AFM conductive probe holder 3, and the insulating base 4 and the AFM conductive probe holder 3 are arranged at the end of the probe microcantilever 2 far from the AFM conductive probe 1, that is, Figure 2 the left end of the probe microcantilever 2 shown in. At the same time, the AFM conductive probe holder 3 is arranged on the side of the probe microcantilever 2 facing the AFM conductive probe, that is, Figure 2 below the probe microcantilever 2 shown in; the electrically insulating base 4 is arranged on the side of the AFM conductive probe microcantilever 2 facing away from the AFM conductive probe holder 3, that is, Figure 2 above the AFM conductive probe holder 3 shown in. The tip 1 of the AFM conductive probe 1 contacts the area to be measured of the material sample 13.

[0034] Above the electrical insulating base 4 is in contact with the heating element 5, and below it is arranged at one end of the probe microcantilever 2 away from the AFM conductive probe holder 3. The electrical insulating base 4 is made of an insulating and heat-conducting material, which can conduct heat well without conducting electricity. The heating element 5 is electrically connected to the excitation source 8. The excitation source 8 is used to provide a heating voltage for the heating element 5 so that the heating element 5 generates heat. Then, the heating element 5 transfers heat energy to the AFM conductive probe through the heat conduction of the insulating base 4 and the probe microcantilever 2, and then transfers it to the nanoscale region where the tip of the AFM conductive probe 1 is in contact with the material sample 13 through the tip of the AFM conductive probe 1, thereby realizing the heating of the nanoscale region of the sample material. The excitation source 8 is electrically connected to the heating element 5 to provide a heating voltage. The heating voltage is 0.5V - 1V, which can well realize the temperature rise of the heating element 5 and heat the probe microcantilever 2 below it. The heat is transmitted through the probe microcantilever 2 to the tip of the AFM conductive probe 1. The tip of the AFM conductive probe 1 generates heat and further transfers the heat to the nanoscale region where the tip is in contact with the material sample 13, thereby realizing the heating of the nanoscale region of the sample material.

[0035] Above the heating element 5 is connected with a thermocouple 6. The thermocouple 6 is made of a heat-conducting material, so that the thermocouple 6 can conduct the heat of the heating element 5 well. That is, one end of the thermocouple 6 is closely connected to the heating element, and the other end is connected to the temperature controller 6. The temperature controller 7 can well measure the temperature of the thermocouple 6, and then realize the indirect measurement of the temperature of the heating element 5.

[0036] It can be understood that since the tip radius of the AFM conductive probe 1 is 10 - 15 nm, which is a nanoscale size, it is technically impossible to directly measure the tip temperature at this time. And because of the relationship between the AFM conductive probe 1 and the probe microcantilever 2, in this solution, the heating temperature of the probe microcantilever 2 is used as the tip temperature of the AFM conductive probe 1.

[0037] Furthermore, the inventor creatively found in the research that there is a specific relationship between the excitation voltage of the excitation source 8 and the tip heating temperature of the AFM conductive probe 1. The tip heating temperature (DT 针尖 ) and the probe excitation voltage (V 激励 ) show a square relationship, that is, DT 针尖 µ V 激励 .

[0038] Figure 3 The measured relationship diagram between the excitation voltage of the excitation source 8 and the tip heating temperature of the AFM conductive probe 1 is given. The theoretical basis is that according to the Joule heat effect, the relationship between the tip heating temperature of the AFM conductive probe 1 and the heating voltage is a quadratic relationship, and Figure 3The measured relationship graph of the tip heating temperature and the excitation voltage of the AFM conductive probe 1 given also indeed presents a good quadratic relationship. Furthermore, by controlling the excitation voltage of the excitation source 8, the heating temperature of the tip of the AFM conductive probe 1 can be well controlled, which is convenient for the operation and control of experimental operators.

[0039] Thereby, through the nano-scale in-situ heating module 100 provided by the present invention, the in-situ heating of the tip of the AFM conductive probe 1 and the local heating effect on the nano-scale contact area between the tip of the AFM conductive probe 1 and the material sample 13 can be successfully achieved.

[0040] In a preferred embodiment, the heating element 5 is coated with an insulating layer, preferably a thermistor of an insulating paint layer. The thermistor is electrically connected to the excitation source 8 and is used for efficient heat conduction without conduction under the action of the voltage of the excitation source 8.

[0041] Please continue to refer to Figure 1-2 , the nano-scale variable temperature infrared absorbance excitation module 200 includes: a laser control system 9, a mid-infrared laser 10, and an infrared optical path control system 11.

[0042] Specifically, the laser control system 9, the pulsed mid-infrared laser 10, and the infrared optical path control system 11 are electrically connected in sequence. The pulsed laser control system 9 can control the pulsed infrared laser 10. By adjusting the laser physical parameters of the pulsed infrared laser 10, the pulsed infrared laser 10 can emit pulsed infrared laser 12 with a controllable pulse frequency and wave number. The infrared optical path control system 11 can regulate the beam collimation, laser energy, and beam focusing of the pulsed pulsed infrared laser, so as to accurately focus the pulsed infrared laser 12 emitted by the pulsed mid-infrared laser 10 on the contact area between the tip of the AFM conductive probe 1 and the sample material 13. When the sample to be measured is heated by the AFM conductive probe 1, a strong nano-scale photothermal expansion effect can be in-situ induced, and then a local photothermal expansion vibration signal is generated.

[0043] According to the photothermal expansion effect, the nano-scale photothermal expansion effect signal is proportional to the local infrared absorbance of the sample. That is, the sample photothermal expansion signal is proportional to the sample temperature change ( u ~ DT ), and the sample temperature change is proportional to the sample absorbed energy ( DT ~ P abs ), the sample absorbed energy is proportional to the infrared absorbance coefficient ( P abs ~ A(s)), therefore, the photothermal expansion signal is also proportional to the infrared absorbance coefficient ((u ~ DT~ P abs ~ A(s)).

[0044] Therefore, the scheme of the present invention constructs a nanoscale variable temperature infrared absorbance excitation module 200, and utilizes the pulsed infrared laser 12 to induce a strong nanoscale photothermal expansion effect in situ in the contact area between the AFM conductive probe tip and the sample material, thereby generating a local photothermal expansion vibration signal, which can well reflect the infrared vibration information of the local chemical functional groups of the sample, making it easier to understand the structural evolution of nanoscale physical phases and chemical functional groups in response to temperature.

[0045] At the same time, by making the pulsed infrared laser 12 generate a local photothermal expansion vibration signal inside the sample material 13, the probe micro-cantilever 2 can be induced to generate a vibration mode of the same frequency, and then the vibration detection of the probe micro-cantilever 2 is realized through the nanoscale variable temperature infrared absorbance detection module 300 to realize the nanoscale variable temperature infrared absorbance analysis of the sample area to be tested of the sample material 13. The details are described below and will not be repeated here.

[0046] In a preferred embodiment, the mid-infrared laser 10 is a pulsed quantum cascade laser light source, which can generate a pulsed infrared laser 10 with high stability, high collimation and adjustable pulses. The wave number range of the pulsed infrared laser 10 is preferably 890-1900 cm -1 , so that its pulse repetition frequency can reach up to 1MHz, and its working pulse repetition frequency is 150kHz-300kHz. The infrared optical path control system 11 focuses the pulse infrared laser 12 onto the surface of the sample material 13, and the preferred range of the beam spot diameter is 40μm to 120μm.

[0047] Please continue reading Figure 1-2 The nanoscale variable temperature infrared absorbance detection module 300 includes: an AFM sample stage 14, an AFM scanner 15, an AFM laser 16, an AFM incident laser beam 17, an AFM reflected laser beam 18, an AFM photoelectric four-quadrant detector 19, a micro-cantilever deformation signal terminal 20, a phase-locked amplifier 21, an AFM control system 22 and a data acquisition and processing display platform 23.

[0048] Specifically, the sample material 13 is set on the AFM sample stage 14. The AFM sample stage 14 is set on the AFM scanner 15, and the AFM scanner 15 is electrically connected to the AFM control system 22, thereby realizing that the AFM sample stage 14, the AFM scanner 15, and the AFM control system 22 are connected in sequence. The AFM control system 22 controls the movement of the AFM scanner 15 in the three-dimensional direction, thereby realizing high-precision positioning and surface scanning of the needle tip of the AFM conductive probe 1 on the surface of the sample material 13.

[0049] Specifically, the probe microcantilever 2 is fixedly connected to the AFM conductive probe 1, and the tip of the AFM conductive probe 1 is in contact with the sample material 13 nanometers away. The AFM laser 16 generates an AFM incident laser beam 17 that irradiates the back of the probe microcantilever 2 where the AFM conductive probe 1 is located, that is, the AFM incident laser beam 17 is incident on the back of the probe microcantilever 2 and forms an AFM reflected laser beam 18 after reflection. The AFM photoelectric quadrant detector 19, the microcantilever deformation signal terminal 20, the lock-in amplifier 21, the AFM control system 22, and the data acquisition, processing, and display platform 23 are electrically connected in sequence.

[0050] Thus, when the local photothermal expansion vibration signal is generated on the surface to be measured where the AFM conductive probe 1 contacts the sample material 13, the conductive probe 1 drives the probe microcantilever 2 to deform, which in turn causes the angle of the reflected laser beam to deflect, and further causes the angle of the AFM reflected laser beam 18 formed by reflection to change. By setting the AFM incident laser beam 17 and the AFM reflected laser beam, the change signal of the probe microcantilever 2 is converted into an optical signal, and then input to the AFM photoelectric quadrant detector 19 to be converted into an electrical signal, and then input to the microcantilever deformation signal terminal 20 of the AFM control system, and then input to the lock-in amplifier 21 for Fourier transform to convert the time-domain signal into a frequency-domain signal, and finally input to the data acquisition, processing, and display platform 23. In this way, the variable-temperature infrared spectrum at a fixed point on the sample material and the variable-temperature nano-chemical microscopic image of the scanned area can be obtained.

[0051] It can be understood that the lock-in amplifier 21 is also electrically connected to the pulsed laser control system 9 to provide a reference signal for the lock-in amplifier 21. Since the signal output from the microcantilever deformation signal terminal 20 detected by the lock-in amplifier 21 is an alternating signal, a reference signal is required at this time. In this system, by electrically connecting the lock-in amplifier 21 to the pulsed laser control system 9, the reference signal of the lock-in amplifier 21 is the alternating signal of the pulsed laser control system 9, and the nano-scale photothermal expansion signal can be well detected by the lock-in amplifier 21.

[0052] Thus, by setting the nano-scale variable-temperature infrared absorbance detection module 300, it is possible to well obtain the surface morphology information of the surface to be measured of the sample material 13 or the physical information of the probe-sample interaction indirectly through the deformation of the probe microcantilever 2.

[0053] Therefore, through the in-situ characterization device for variable-temperature infrared absorbance at the nanoscale provided by the present invention, a nanoscale in-situ heating module 100, a nanoscale variable-temperature infrared absorbance excitation module 200, and a nanoscale variable-temperature infrared absorbance detection module 300 are provided. By using the nanoscale in-situ heating module 100 of the present invention to perform nanoscale in-situ heating on the area to be measured of the sample material 13, and by using the nanoscale variable-temperature infrared absorbance excitation module 200 to send pulsed infrared laser 12 to the contact area between the sample material 13 and the AFM tip, a local photo-thermal expansion vibration signal is generated inside the sample material 13 by the pulsed infrared laser 12 under the combined action of the nanoscale in-situ heating module 100 and the nanoscale variable-temperature infrared absorbance excitation module 200, thereby inducing the probe microcantilever 2 to generate a co-frequency vibration mode.

[0054] At this time, by using the nanoscale variable-temperature infrared absorbance detection module 300, the nanoscale variable-temperature infrared absorbance analysis is indirectly realized by detecting the vibration of the probe microcantilever 2, and then the variable-temperature infrared spectrum at a fixed point at the nanoscale of the sample material and the variable-temperature nano-chemical microimage of the scanned area are obtained.

[0055] Specifically, when it is necessary to obtain the variable-temperature infrared spectrum at a fixed point at the nanoscale of the sample material, the tip of the AFM conductive probe 1 is fixed to the area to be measured of the sample to be measured, and the device provided by the present invention is used to detect the nanoscale photo-thermal expansion effect at different heating temperatures and different wave numbers, and a lock-in amplifier is used to detect the nanoscale photo-thermal expansion signal, thereby obtaining the variable-temperature nanoscale infrared spectrum at this point.

[0056] When it is necessary to obtain the variable-temperature nano-chemical microimage of the scanned area of the sample to be measured, the tip of the AFM conductive probe 1 is used to in-situ detect the nanoscale photo-thermal expansion effect signals of all pixel points in the scanned area at a certain wave number, and a lock-in amplifier is used to detect the nanoscale photo-thermal expansion signal, thereby obtaining the variable-temperature nano-chemical microimage.

[0057] It can be understood that the AFM conductive probe 1 can realize the functions of nanoscale in-situ heating, in-situ excitation of the nanoscale photo-thermal effect, and in-situ detection of the nanoscale photo-thermal signal, and it can be realized by the contact mode of the atomic force microscope in the working mode. In a preferred embodiment, the typical value of the tip force is 1 nN - 30 nN, and the interaction contact radius between the tip and the sample material is 10 - 30 nm, ensuring the high nanoscale resolution of the in-situ detection of the infrared absorbance of the sample material 13 by the tip of the AFM conductive probe 1.

[0058] It should be noted that there are many implementation manners of the lock-in amplifier 21 in the prior art, and the present invention does not limit this. In a preferred implementation manner, the lock-in amplifier 21 is preferably a lock-in amplifier with high measurement sensitivity and strong anti-interference ability, which can well realize the high-sensitivity detection of weak signals. For the lock-in amplifier 21, any existing commercial lock-in amplifier can be used, and the present invention does not limit this.

[0059] The data processing and display module 23 is electrically connected to the pulsed laser control system 9, the lock-in amplifier 21, and the AFM control system 22. As a signal processing module and result display module based on a computer platform, it can display the topography image of the area to be measured. By utilizing the thermal effect of the pulsed infrared laser and the frequency-domain transformation theory of periodic signals, the relative value of the infrared absorbance of the nano-scale micro-region of the sample material can be calculated by a computer, and the AFM topography image and the nano-infrared absorbance surface distribution imaging of the material sample are completed synchronously in-situ, and each group of images is scanned and imaged at one time. Thus, the in-situ detection of the nano-scale infrared spectrum of a single point of the sample material under the action of a continuous-wave pulsed infrared laser, and the nano-scale high-resolution chemical microscopy imaging of the surface scanning area of the sample material under the action of a single-wave pulsed infrared laser can be realized, and the analysis of the variable-temperature infrared absorbance at the nano-scale can be realized.

[0060] In a preferred implementation manner, using the perovskite MAPbI3 (CH3NH3PbI3) crystal material as the sample material to be measured, a typical application study of the nano-scale variable-temperature infrared absorbance in-situ characterization device established by the present invention was carried out. Perovskite materials have advantages such as excellent optoelectronic properties, high energy conversion efficiency, easy solution processing, high light absorption coefficient, long diffusion length, and high carrier mobility, and are widely regarded as one of the most promising solar cell materials. The microstructure stability of this material is an important concern in this material field. Applying the nano-scale variable-temperature infrared absorbance in-situ characterization device established by the present invention can well realize the in-situ characterization of the nano-scale variable-temperature infrared spectrum of the microstructure of the perovskite MAPbI3 material sample and the study of variable-temperature nano-chemical microscopy imaging.

[0061] Please refer to Figure 4 , Figure 4 which gives the nano-infrared spectrum characterization results of the perovskite MAPbI3 crystal material at different heating temperatures. Figure 4 In (a), it is the nano-infrared spectrum result at 26.5 o °C - 34.7 o °C. Figure 4 In (b), it is the nano-infrared spectrum result at 34.7 o °C - 45.1 o °C. Figure 4 In (c), it is at 51.4 o °C - 59.6o Nano-infrared spectroscopy results of C. Based on Figure 4 the detection results in A-4C, it can be seen that at room temperature, on the absorption spectrum of MAPbI3, two obvious absorption peaks at 1579.5 and 1464.5 cm -1 appear, corresponding to the bending vibration of N-H bond and the stretching vibration of C-N bond respectively. And as the temperature increases, the bending vibration peak of N-H bond generally shows a trend of shifting to higher frequencies, indicating that as the temperature increases, the molecular thermal motion of the sample material intensifies, resulting in a gradual increase in the distance of N-H…I hydrogen bond, thus causing structural changes between the Pb-I inorganic framework and the organic amine molecules. This not only provides new insights into the nano-scale structural evolution of the perovskite MAPbI3 material, but also proves the positive effect of the solution provided by the present invention on the variable-temperature infrared absorbance analysis at the nano-scale.

[0062] Please refer to Figure 5 , Figure 5 shows the nano-chemical microscopy results of the perovskite MAPbI3 crystal material at different heating temperatures. Figure 5 In (a), (b), and (c) are the nano-scale chemical micrographs at heating temperatures of 29 o °C, 31.1 o °C, and 34.7 o °C respectively. The nano-chemical microscopy results clearly show the ferroelastic domain structure of the perovskite MAPbI3 crystal material and its dynamic behavior of nucleation and growth with temperature. At the same time, the dark contrast of the domain walls indicates that the concentration of methylammonium ions (MA + +) near them is relatively low. As the temperature increases, the triangular domain nuclei grow longitudinally, showing the + relatively fast diffusion kinetic characteristics of MA+ and also proving the positive effect of the solution provided by the present invention on the variable-temperature infrared absorbance analysis at the nano-scale.

[0063] Figure 6 shows the nano-scale chemical micrographs of another scanning area of the perovskite MAPbI3 crystal material at a heating temperature of 34.7 o °C and different heating times. Among them Figure 6 in (a) is the AFM topography image result of a 50 mm´50mm scanning area of the methylammonium lead iodide crystal sample, (b) is the chemical micrograph result of the same scanning area before heating, (c) is the chemical micrograph result of the same scanning area with the tip heating temperature of 34.7 o °C, Figure 6 in (d), (e), and (f) are the chemical micrograph results of the same scanning area with the tip heating temperature of 34.7 oUnder 0 °C, the chemical microscopy images at different heating times of 18 minutes, 63 minutes, and 72 minutes. The chemical imaging results clearly show the regulatory effect of the tip temperature on the domain structure of MAPbI3 crystals. While the chemical microscopy images showing its variation over time clearly demonstrate the close correlation between the dynamic evolution of the domain structure and the transport of methylammonium ions, and also prove the positive effect of the solution provided by the present invention on the variable-temperature infrared absorbance analysis at the nanoscale.

[0064] It can be seen that Figure 4-6 The examples show that the in-situ variable-temperature infrared absorbance characterization device at the nanoscale can well complete the in-situ characterization of the variable-temperature infrared spectrum in the micro-region at the nanoscale of the material and the micro-region surface distribution microscopy imaging (chemical imaging) of the variable-temperature infrared absorbance. The solution of the present invention develops an in-situ variable-temperature infrared absorbance characterization device on the AFM nanoscale platform to realize the in-situ synchronous microscopy imaging of the AFM topography image of the material, the in-situ acquisition of the variable-temperature nanoscale infrared spectrum at a single point under continuous wave numbers, and the variable-temperature infrared absorbance nanoscale micro-region surface distribution, providing a simple-principle and direct-testing in-situ nanoscale characterization technology for the in-depth study of the chemical composition and structure of the material.

[0065] In summary, the outstanding advantage of the present invention combines the photo-thermal expansion effect of the interaction between the pulsed mid-infrared and the sample material, the infrared absorption of the sample material, the nanoscale inspection of the atomic force microscope probe, and the Fourier transform of the periodic signal of the periodic signal to establish a new method and device for the in-situ high-resolution characterization of the variable-temperature infrared absorbance at the nanoscale based on the atomic force microscope, realizing the in-situ acquisition of the nanoscale infrared spectrum of the sample material under variable-temperature conditions and high-resolution chemical imaging, and providing an ultra-high-resolution in-situ characterization technology for the microscopy imaging of the infrared absorbance closely related to the nanoscale phase composition and structure analysis of the material.

[0066] The in-situ variable-temperature infrared absorbance characterization device provided by the present invention has unique functions of in-situ characterization of the variable-temperature infrared spectrum at the nanoscale, in-situ microscopy imaging of the variable-temperature infrared absorbance at the nanoscale, and in-situ synchronous characterization of the topography image, and has advantages such as ultra-high resolution at the nanoscale, high sensitivity, high signal-to-noise ratio, and direct testing. The key technical device described in the present invention has a simple structure and strong compatibility, is suitable for combination with different commercial AFM control systems, is a new technology that is easy to promote and apply, and is expected to obtain important applications in the fields of low-dimensional materials, layered materials, nanomaterials, and other materials.

[0067] The foregoing description of the preferred embodiments has been provided so that any person skilled in the art can make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0068] It will be understood that, as used in the specification and claims of the present invention, unless the context clearly dictates otherwise, the terms "a," "an," "the," and / or "said" are not intended to be singular, but may include the plural. In general, the terms "comprising" and "including" are used to indicate the inclusion of the specifically identified steps and elements, and these steps and elements do not constitute an exclusive listing, and the method or apparatus may also include other steps or elements.

[0069] Unless otherwise specifically stated, the relative arrangements of the components and steps, numerical expressions and values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for the sake of convenience of description, the dimensions of the various parts shown in the drawings are not drawn in actual proportional relationship. Technologies, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the said technologies, methods and devices should be regarded as part of the authorized specification. In all the examples shown and discussed herein, any specific values should be construed as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that like reference numerals and letters denote like items in the following drawings, and thus, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0070] In addition, it should be noted that the use of terms such as "first," "second," etc. to define components is only for the convenience of distinguishing the corresponding components. Without further statement, the above terms have no special meaning and thus should not be construed as limiting the scope of the present invention. In addition, although the terms used in the present invention are selected from well-known and commonly used terms, some of the terms mentioned in the specification of the present invention may be selected by the inventor according to his or her judgment, and their detailed meanings are described in the relevant parts of the present description. In addition, it is required to understand the present invention not only through the actual terms used, but also through the meaning implied by each term.

[0071] Flowcharts are used in the present invention to illustrate the operations performed by the system according to the embodiments of the present invention. It should be understood that the operations above or below do not necessarily have to be executed precisely in order. On the contrary, various steps can be executed in reverse order or simultaneously. Also, one or more operations can be added to these processes, or one or several steps can be removed from these processes.

Claims

1. An in-situ characterization device for variable-temperature infrared absorbance at the nanoscale, characterized in that, It includes an in-situ heating module, a variable-temperature infrared excitation module, and a variable-temperature infrared detection module; The in-situ heating module includes a heating element, an AFM conductive probe, and a probe microcantilever capable of conducting heat. One end of the probe microcantilever is in thermal contact with the heating element, and the other end is connected to the AFM conductive probe to transfer the thermal energy of the heating element to the AFM conductive probe. The AFM conductive probe is in contact with the area to be measured of the sample to be measured to achieve in-situ heating of the area to be measured; The variable-temperature infrared excitation module is used to emit pulsed infrared laser to the area to be measured and is electrically connected to the variable-temperature infrared detection module to send the laser information of the pulsed infrared laser; Wherein Under the action of the pulsed infrared laser, the area to be measured for in-situ heating generates local optothermal expansion vibration, which drives the probe microcantilever to vibrate at the same frequency; The variable-temperature infrared detection module is used to obtain the vibration information of the probe microcantilever and obtain the local optothermal expansion vibration information at least based on the vibration information and the laser information, so as to realize the nano-scale variable-temperature infrared absorbance analysis of the area to be measured.

2. The in-situ characterization device for variable-temperature infrared absorbance at the nanoscale according to claim 1, wherein The variable-temperature infrared detection module includes an AFM laser, an AFM photoelectric four-quadrant detector, and a data processing and display platform. The data processing and display platform is electrically connected to the AFM photoelectric four-quadrant detector and the variable-temperature infrared excitation module. Wherein The AFM laser is used to send an AFM incident laser beam to the probe microcantilever. The AFM photoelectric four-quadrant detector is used to receive the AFM reflected laser beam refracted from the probe microcantilever and send it to the data processing and display platform in the form of an electrical signal; The data processing and display platform completes the nano-scale variable-temperature infrared absorbance analysis of the area to be measured based on the electrical signal sent by the AFM photoelectric four-quadrant detector and the laser information sent by the variable-temperature infrared excitation module.

3. The in-situ characterization device for nano-scale variable-temperature infrared absorbance according to claim 2, wherein, The variable-temperature infrared detection module further includes a lock-in amplifier. The lock-in amplifier is electrically connected to the AFM photoelectric four-quadrant detector and the data processing and display platform. Wherein, The lock-in amplifier is used to perform Fourier transform on the electrical signal sent by the AFM photoelectric four-quadrant detector and then send it to the data processing and display platform to realize the conversion of the time-domain signal into the frequency-domain signal.

4. The in-situ characterization device for variable-temperature infrared absorbance at the nanoscale according to claim 2, characterized in that, The contact position of the AFM incident laser beam and the probe microcantilever is set on the side facing away from the AFM probe holder and at the position corresponding to the AFM probe holder.

5. The in-situ characterization device for variable-temperature infrared absorbance at the nanoscale according to any one of claims 1-4, characterized in that, The variable-temperature infrared detection module includes an AFM sample stage, an AFM scanner, and an AFM control system. The sample to be measured is arranged on the AFM sample stage. The AFM scanner is fixedly connected to the AFM sample stage. Wherein The AFM control system is used to control the three-dimensional movement of the AFM scanner to achieve high-precision positioning and area scanning of the area to be measured of the sample to be measured.

6. The in-situ characterization device for variable-temperature infrared absorbance at the nanoscale according to any one of claims 1-4, characterized in that The in-situ heating module further includes an excitation source. The excitation source is used to provide a heating voltage for the heating element to selectively adjust the thermal energy emitted by the heating element. Wherein The heating element is composed of a thermistor wrapped by an insulating layer. The thermistor is electrically connected to the excitation source.

7. The in-situ characterization device for variable-temperature infrared absorbance at the nanoscale according to any one of claims 1-4, characterized in that The in-situ heating module further includes an insulating base made of a heat-conductive material, one side of the insulating base is connected to the heating element, and the other side is connected to the probe microcantilever, wherein the insulating base is used to transfer the heat of the heating element to the probe microcantilever while preventing the heating element from making electrical contact with the probe microcantilever.

8. The in-situ characterization device for nano-scale variable-temperature infrared absorbance according to any one of claims 1-4, characterized in that, The in-situ heating module further includes a temperature controller and a thermocouple made of a heat-conductive material. The thermocouple is in thermal contact with the heating element and is connected to the temperature controller. The temperature controller indirectly obtains the tip heating temperature of the AFM conductive probe based on the temperature of the thermocouple.

9. The in-situ characterization device for variable-temperature infrared absorbance at the nanoscale according to any one of claims 1-4, characterized in that, The contact area between the AFM conductive probe and the sample to be measured is 10 - 30 nm, and the typical value of the acting force is 1 nN to 30 nN.

10. The in-situ characterization device for variable-temperature infrared absorbance at the nanoscale according to any one of claims 1-4, characterized in that, The variable-temperature infrared excitation module includes a pulsed laser control system, a mid-infrared laser, and an infrared optical path control system, wherein the pulsed laser control system is electrically connected to the mid-infrared laser to control the mid-infrared laser to emit the pulsed infrared laser, and is electrically connected to the variable-temperature infrared detection module to send the laser information of the pulsed infrared laser; the infrared optical path control system is used to focus the pulsed infrared laser on the area to be measured to in-situ excite the nano-scale variable-temperature photothermal expansion signal in the in-situ heated area to be measured.

11. The in-situ characterization device for variable-temperature infrared absorbance at the nanoscale according to any one of claims 1-4, characterized in that, The nano-scale variable-temperature infrared absorbance analysis of the area to be measured at least includes the fixed-point nano-scale variable-temperature infrared spectroscopy analysis of the sample material and the variable-temperature nano-chemical microscopy analysis of the scanned area.

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