A method and device for monitoring perovskite degradation phase change process

Abstract

The present invention relates to a method for monitoring the degradation phase transition of perovskite. By applying laser light to a sample, the intensity change of the second harmonic generated by the sample is detected, and an image of the sample's degradation phase transition is obtained. The degradation phase transition of the sample is then analyzed and calibrated based on the second harmonic curve and the image of the sample's degradation process. The method can more easily and conveniently monitor the degradation phase transition of perovskite samples and is suitable for large-scale application.

Description

Technical Field

[0001] The present invention relates to the field of crystal phase transition, and in particular to a method for monitoring a perovskite degradation phase transition process. Background Art

[0002] In recent years, organic-inorganic hybrid perovskites (OIHPs) have seen rapid development in solar cells due to their low synthesis cost, high light absorption coefficient, and high photoelectric conversion efficiency. However, perovskite materials are structurally unstable and prone to degradation and phase transitions in the operating environment of solar cells, resulting in a loss of photoelectric conversion function. This significantly affects the efficiency and stability of solar cell devices and significantly hinders the commercial development of this technology. Therefore, monitoring and studying the degradation and phase transition process of perovskites is particularly important.

[0003] The existing method for monitoring the degradation phase transition of perovskite is to directly observe the degradation phase transition process of perovskite under electron beam irradiation at the atomic scale through selected area electron diffraction, proving the existence of intermediate phases in the degradation process of perovskite under electron beam irradiation, and then studying the degradation phase transition process of perovskite.

[0004] However, when using the existing perovskite degradation phase transition monitoring method to study the degradation phase transition process of perovskite, selected area electron diffraction has high requirements and costs for experimental instruments, and the process of analyzing and processing the selected area electron diffraction pattern is also very complicated and tedious, which is not conducive to large-scale promotion. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a method for monitoring the degradation phase transition process of perovskite, which can indirectly study the degradation phase transition process of perovskite by detecting the intensity of the second harmonic, thereby achieving simple and low-cost monitoring.

[0006] A monitoring device for a perovskite degradation phase change process comprises a light source, an excitation unit, and an analysis unit. The excitation unit is arranged in the direction of an initial light beam emitted by the light source, and the analysis unit is arranged in the direction of the outgoing light beam of the excitation unit. The excitation unit comprises a first spectroscope and a sample made of perovskite. The first spectroscope is arranged between the sample and the light source. The initial light beam enters the first spectroscope and is emitted along one outgoing direction of the first spectroscope to form a sample incident light beam. The sample incident light beam irradiates the sample to generate a second harmonic. The second harmonic propagates in a direction opposite to the direction of the sample incident light beam to form a sample reflected light beam. The sample reflected light beam enters the first spectroscope and is emitted along another outgoing direction of the first spectroscope to form an information light beam. The information light beam is received by the analysis unit to obtain a second harmonic curve and a phase change image, and the degradation phase change process of the sample is analyzed and calibrated.

[0007] Furthermore, the perovskite undergoes lattice structure changes during the degradation phase transition process, which produces different second harmonic effects.

[0008] Furthermore, the analysis unit includes a second spectrometer, a spectrometer and a camera. The second spectrometer transmits the information beam to form a spectral analysis beam, and reflects the information beam to form an image analysis beam. The spectrometer receives the spectral analysis beam to obtain a second harmonic curve and analyzes the degradation phase change process of the calibration sample. The camera receives the image analysis beam and analyzes the phase change image of the sample, and calibrates the degradation phase change process of the sample corresponding to the second harmonic curve.

[0009] Furthermore, the excitation unit also includes a microscope objective lens, which is arranged between the sample and the first spectrometer, and focuses the sample incident light beam to form a sample microscopic light beam. The sample microscopic light beam is irradiated on the sample to generate a second harmonic, and the second harmonic propagates in the opposite direction of the sample microscopic light beam to form a sample reflected light beam. The microscope objective lens amplifies the sample reflected light beam to form a sample amplified light beam, and the sample amplified light beam propagates in the opposite direction of the sample incident light beam.

[0010] Furthermore, the excitation unit further includes a displacement stage, the sample is arranged on the displacement stage, and the position of the monitored sample is changed by changing the displacement stage.

[0011] Furthermore, it also includes an amplifying unit, which is arranged between the light source and the first spectrometer, and includes a first magnifying lens and a second magnifying lens. The first magnifying lens is arranged between the light source and the second magnifying lens, and its focal length is smaller than that of the second magnifying lens. The rear focus of the first magnifying lens away from the light source is confocal with the front focus of the second magnifying lens close to the light source. The amplifying unit expands the initial light beam to form an initial amplified light beam.

[0012] Furthermore, it also includes a collimating unit, which is arranged between the light source and the excitation unit, and includes a first collimating lens and a second collimating lens. The first collimating lens is arranged between the light source and the second collimating lens. The rear focus of the first collimating lens away from the light source is confocal with the front focus of the second collimating lens close to the light source. The collimating unit collimates the initial amplified light beam to form an initial collimated light beam.

[0013] Furthermore, it also includes a focusing lens, which is arranged between the excitation unit and the analysis unit to focus the information light beam.

[0014] Furthermore, it also includes a filter, which is arranged between the excitation unit and the analysis unit to filter out the stray light of the information beam to obtain a filtered beam containing only second harmonic components. The filtered beam is received by the analysis unit to obtain a second harmonic curve and a phase change image and analyze the degradation phase change process of the calibration sample.

[0015] The present invention also provides a method for monitoring the degradation phase change process of perovskite, which adds laser action to the sample, detects the change in the second harmonic intensity generated by the sample and obtains the degradation phase change image of the sample, and calibrates the degradation phase change process of the sample through the second harmonic curve and the phase change image analysis of the sample degradation process.

[0016] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the structure of the monitoring device for the perovskite degradation phase change process of the present invention.

[0018] Figure 2 Schematic diagram of the perovskite degradation phase transition process.

[0019] Figure 3 Schematic diagram of the change in laser action caused by the change in lattice structure during the degradation phase transition of a perovskite.

[0020] Figure 4 This is a curve of the change in second harmonic intensity generated by laser during the perovskite degradation phase transition process. DETAILED DESCRIPTION

[0021] The inventors carefully analyzed existing methods for monitoring perovskite degradation phase transitions and discovered that because the degradation phase transition of perovskites occurs through changes in the crystal structure at the atomic level, direct monitoring of the perovskite degradation phase transition requires atomic-level observation images obtained through selected area electron diffraction. This leads to high equipment requirements, complex operation, and high costs. Therefore, the applicants attempted to indirectly monitor the degradation phase transition of perovskites by adding laser light to generate second harmonics (SHG) and detecting changes in the intensity of the second harmonics.

[0022] Based on the above invention concept, please refer to Figure 1 The present invention provides a monitoring device for perovskite degradation phase change, including a light source 10, an amplifying unit 20, a collimating unit 30, an excitation unit 40, a filter 50, a focusing lens 60, and an analyzing unit 70.

[0023] The light source 10 is a femtosecond laser, which emits an initial light beam. The initial light beam enters the amplification unit 20, where the beam diameter is expanded by the amplification unit 20 to form an initial amplified light beam. The initial amplified light beam enters the collimation unit 30, where it is collimated and shaped to form an initial collimated light beam. The initial collimated light beam enters the excitation unit 40 to form an information light beam containing perovskite degradation phase change information. The information light beam is filtered by the filter 50 to form a filtered light beam containing only the second harmonic. The filtered light beam is focused by the focusing lens 60 and enters the analysis unit 70 to analyze the degradation phase change process of the perovskite.

[0024] The magnifying unit 20 includes a first magnifying lens 21 and a second magnifying lens 22. The first magnifying lens 21 is disposed between the light source 10 and the second magnifying lens 22. The first magnifying lens 21 has a smaller focal length than the second magnifying lens 22. The rear focal point of the first magnifying lens 21, which is farther from the light source 10, is confocal with the front focal point of the second magnifying lens 22, which is closer to the light source 10. After passing through the first magnifying lens 21 and the second magnifying lens 22, the initial light beam expands its beam diameter to form an initial magnified light beam. The expanded beam diameter of the initial magnified light beam compared to the initial light beam can be controlled based on the focal length ratio of the first magnifying lens 21 to the second magnifying lens 22. The greater the focal length of the second magnifying lens 22 compared to the first magnifying lens 21, the greater the degree of beam diameter magnification.

[0025] The collimating unit 30 includes a first collimating lens 31 and a second collimating lens 32. The first collimating lens 31 is disposed between the light source 10 and the second collimating lens 32. The first collimating lens 31 has the same focal length as the second collimating lens 32, and the rear focus of the first collimating lens 31 is confocal with the front focus of the second collimating lens 32. After passing through the first collimating lens 31 and the second collimating lens 32, the initial amplified light beam forms a more collimated initial collimated light beam, and the beam diameter thereof does not change.

[0026] The excitation unit 40 includes a first beam splitter 41, a microscope objective 42, a sample 43, and a translation stage 44. The first beam splitter 41 transmits a collimated light beam to form a sample incident light beam, which is then focused by the microscope objective 42 to form a sample microscopic light beam. The sample microscopic light beam is irradiated onto the sample 43 and generates a second harmonic, which propagates in the opposite direction of the sample microscopic light beam to form a sample reflected light beam. The microscope objective 42 amplifies the sample reflected light beam to form a sample amplified light beam, which propagates in the opposite direction of the sample incident light beam. The sample amplified light beam is reflected by the first beam splitter 41 to form an information light beam and exit the excitation unit 40. Sample 43 is initially a perovskite sample, which is placed on the translation stage 44. As the translation stage 44 moves, the focusing position of the microscope objective 42 on the sample 43 also moves, allowing accurate acquisition of degradation phase change information corresponding to any position on the surface of the sample 43.

[0027] The filter 50 is arranged between the excitation unit 40 and the analysis unit 70 to filter the information beam, and filter out the beam components except the second harmonic containing the degradation phase change information of the sample 43 in the information beam to form a filtered beam containing pure second harmonic.

[0028] The focusing lens 60 is disposed between the filter 50 and the analysis unit 70 to focus the filtered light beam and reduce the beam diameter of the filtered light beam, thereby facilitating subsequent reception and analysis of the light beam.

[0029] The analysis unit includes a second spectrometer 10, a spectrometer 11 and a camera 12. The second spectrometer 10 transmits the focused filtered light beam to form a spectral analysis beam, and reflects the focused filtered light beam to form an image analysis beam. The spectrometer 11 receives the spectral analysis beam to obtain a second harmonic curve and analyzes the degradation phase change process of the calibration sample 43. The camera 12 receives the image analysis beam and analyzes the phase change image of the sample 43, and further calibrates the degradation phase change process of the sample according to the second harmonic curve.

[0030] In the present invention, taking one of the perovskites MAPbI3 as an example, the principle and process of monitoring its degradation phase transition are explained in detail.

[0031] See also Figure 2 The MAPbI3 will be corroded by water and oxygen in an environment with both water and oxygen, and will undergo degradation phase change from the initial MAPbI3 solid phase to MAPbI3 water phase, and then gradually change to MA x PbI yFinally, PbI2 is formed. The phase transition images captured by the camera also show that the color of the micronized bands of MAPbI3 gradually changes from black to yellow. This proves that there is a clear phase transition during the degradation of MAPbI3. However, it is difficult to define the phase transition process simply by observing the macroscopic color change on the surface with the naked eye. In order to more accurately monitor the degradation phase transition process of MAPbI3, other more sophisticated monitoring methods are needed.

[0032] See also Figure 3 MAPbI3 is centrosymmetric in its initial solid phase and cannot generate second harmonics under the excitation of a 1000nm femtosecond laser. However, after the degradation phase transition of MAPbI3, its lattice structure collapses. During this process, many non-centrosymmetric structures are generated and disappear. Therefore, under the excitation of a femtosecond laser, a second harmonic with a wavelength of 500nm and varying intensity will be generated.

[0033] See also Figure 4 , the monitoring device for the perovskite degradation phase change process of the present invention was used to test and obtain the second harmonic intensity change curve detected by the spectrometer during the seven-day degradation of MAPbI3, wherein the horizontal axis is the wavelength corresponding to the second harmonic, and the vertical axis is the intensity corresponding to the second harmonic. It can be seen that in the initial solid phase state of MAPbI3, the second harmonic intensity detected by the spectrometer is completely 0, proving that MAPbI3 at this time is indeed a completely centrosymmetric MAPbI3 solid phase; after the first day, it can be seen that a certain intensity change occurs at the 500nm position, and gradually increases before the sixth day, proving that at this time, the MAPbI3 aqueous phase changes to MAPbI3. x PbI y process; On the seventh day, a second luminescence peak appeared, which was the result that part of MAPbI3 had been completely degraded into PbI2. Since the wavelength of the second harmonic generated by PbI2 was the same as that of MA x PbI y The luminescence peak formed when PbI2 appears can be observed. According to the principle and process of MAPbI3 degradation phase transition, the process can be calibrated one by one and synchronized with the phase transition image captured by the camera.

[0034] Those skilled in the art will understand that the samples used in the monitoring device for the perovskite degradation phase change process of the present invention can be a variety of perovskites with lattice structure changes that produce different second harmonic effects during the degradation phase change process, such as CsPbBr3, MAPbBr3, CsPbI3, etc., and are not limited to MAPbI3 materials.

[0035] The above-described embodiments merely represent several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous modifications and improvements without departing from the spirit of the present invention, and the present invention is intended to encompass such modifications and variations.

Claims

1. A monitoring device for the perovskite degradation phase transition process, characterized by: The invention comprises a light source, an excitation unit and an analysis unit, wherein the excitation unit is arranged in the direction of an initial light beam emitted by the light source, and the analysis unit is arranged in the direction of an outgoing light beam of the excitation unit; the excitation unit comprises a first spectroscope and a sample made of perovskite, the first spectroscope is arranged between the sample and the light source, the initial light beam enters the first spectroscope and is emitted along one outgoing direction of the first spectroscope to form a sample incident light beam, the sample incident light beam irradiates the sample to generate a second harmonic, the second harmonic propagates in the opposite direction of the sample incident light beam to form a sample reflected light beam, the sample reflected light beam enters the first spectroscope and is emitted along another outgoing direction of the first spectroscope to form an information light beam, the information light beam is received by the analysis unit to obtain a second harmonic curve and a phase change image, and the degradation phase change process of the calibration sample is analyzed; wherein the phase change image captured by the camera is used to observe the macroscopic color change of the perovskite surface.

2. The monitoring device for the perovskite degradation phase change process according to claim 1, characterized in that: The perovskite undergoes lattice structure changes during the degradation phase transition process, which produces different second harmonic effects.

3. The monitoring device for the perovskite degradation phase change process according to claim 2, characterized in that: The analysis unit includes a second spectrometer, a spectrometer and a camera. The second spectrometer transmits the information beam to form a spectral analysis beam and reflects the information beam to form an image analysis beam. The spectrometer receives the spectral analysis beam to obtain a second harmonic curve and analyzes the degradation phase change process of the calibration sample. The camera receives the image analysis beam and analyzes the phase change image of the sample, and calibrates the degradation phase change process of the sample corresponding to the second harmonic curve.

4. The monitoring device for the perovskite degradation phase change process according to claim 3, characterized in that: The excitation unit also includes a microscope objective lens, which is arranged between the sample and the first spectroscope, and focuses the sample incident light beam to form a sample microscopic light beam. The sample microscopic light beam is irradiated on the sample to generate a second harmonic, and the second harmonic propagates in the opposite direction of the sample microscopic light beam to form a sample reflected light beam. The microscope objective lens amplifies the sample reflected light beam to form a sample amplified light beam, and the sample amplified light beam propagates in the opposite direction of the sample incident light beam.

5. The monitoring device for the perovskite degradation phase change process according to claim 4, characterized in that: The excitation unit further includes a displacement stage, the sample is placed on the displacement stage, and the position of the monitored sample can be changed by changing the displacement stage.

6. The monitoring device for the perovskite degradation phase change process according to claim 5, characterized in that: It also includes an amplifying unit, which is arranged between the light source and the first spectrometer, and includes a first magnifying lens and a second magnifying lens. The first magnifying lens is arranged between the light source and the second magnifying lens, and its focal length is smaller than that of the second magnifying lens. The rear focus of the first magnifying lens away from the light source is confocal with the front focus of the second magnifying lens close to the light source. The amplifying unit expands the initial light beam to form an initial amplified light beam.

7. The monitoring device for the perovskite degradation phase change process according to claim 6, characterized in that: It also includes a collimating unit, which is arranged between the light source and the excitation unit, and includes a first collimating lens and a second collimating lens. The first collimating lens is arranged between the light source and the second collimating lens. The rear focus of the first collimating lens away from the light source is confocal with the front focus of the second collimating lens close to the light source. The collimating unit collimates the initial amplified light beam to form an initial collimated light beam.

8. The monitoring device for the perovskite degradation phase change process according to claim 7, characterized in that: The device also includes a focusing lens, which is arranged between the excitation unit and the analysis unit and focuses the information light beam.

9. The monitoring device for the perovskite degradation phase change process according to claim 8, characterized in that: It also includes a filter, which is arranged between the excitation unit and the analysis unit to filter the stray light of the information beam to obtain a filtered beam containing only second harmonic components. The filtered beam is received by the analysis unit to obtain a second harmonic curve and a phase change image and analyze the degradation phase change process of the calibration sample.

10. A method for monitoring a perovskite degradation phase transition process, applied to the device for monitoring a perovskite degradation phase transition process according to any one of claims 1 to 9, characterized in that: Laser action is added to the sample, the change in the second harmonic intensity generated by the sample is detected, and the degradation phase change image of the sample is obtained. The degradation phase change process of the sample is calibrated through the second harmonic curve and the phase change image analysis of the sample degradation process.

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