System and method for in-situ monitoring mechanical properties of flexible perovskite solar cells

Abstract

This invention relates to a system and method for in-situ monitoring of the mechanical properties of flexible perovskite solar cells. During imaging and bending tests, the flexible perovskite solar cell is inverted and placed on a sample stage within a cell bending mechanism. Photocurrent probes connected to both sides of a photocurrent detection device are inserted into the positive and negative electrode dielectrics, respectively. An electrically driven folding mirror is raised, and a laser emitted from a laser is incident on a two-dimensional scanning galvanometer. The sample fluorescence signal output from the two-dimensional scanning galvanometer is then incident on a detector. During wide-field dynamics testing of the half-cell structure, the half-cell structure is inverted and placed on the sample stage within the cell bending mechanism. The electrically driven folding mirror is lowered, and the laser emitted from the laser is reflected by the electrically driven folding mirror and then incident on a microscope after passing through an aperture and a beam expander. This invention enables multiple tests of flexible perovskite solar cells within the same system and allows for a microscopic understanding of the problems existing in flexible perovskite solar cells.

Description

Technical Field

[0001] This invention relates to the field of flexible perovskite solar cell testing, specifically a system and method for in-situ monitoring of the mechanical properties of flexible perovskite solar cells. Background Technology

[0002] Flexible perovskite solar cells offer advantages such as being lightweight, thin, flexible, easily bendable, and portable, making them more suitable for everyday use. The biggest challenges currently facing flexible perovskite solar cells are improving photoelectric conversion efficiency and stability. Stability primarily includes the stability of the device itself and its mechanical stability. Mechanical stability is crucial because flexible perovskite solar cells are subject to repeated stretching and bending during daily use, which affects the cell's efficiency and lifespan.

[0003] Current research on the mechanical stability of flexible batteries focuses more on macroscopic changes such as photoelectric conversion efficiency and resistance. Further research on this process at the micro-nano scale is still relatively lacking. Among the current photoelectric imaging technologies with spatial resolution at the micro-nano scale, the main ones include photoconductive atomic force microscopy (PC-AFM), Kelvin probe force microscopy (KPFM), and near-field scanning optical microscopy (SNOM). However, since these technologies all rely on the tip scanning mode of atomic force microscopy (AFM) to obtain information about the sample surface, and the actual complete device contains modified passivation layers, transport layers, and metal electrodes, the tip cannot contact the perovskite film surface and thus cannot obtain information. Therefore, photoelectric imaging technologies based on atomic force microscopy cannot test the complete battery under real working conditions. While near-field scanning optical microscopy (SNOM) can break the optical diffraction limit and achieve near-field optical resolution of 60-100 nm, it cannot characterize complete devices because the distance between the sample and the tip must be kept within the near-field range (within a few nanometers to tens of nanometers). The thickness of the metal electrodes in a complete battery device is generally between 80 and 100 nm, which is far beyond the near-field distance. Summary of the Invention

[0004] The purpose of this invention is to provide a system and method for in-situ monitoring of the mechanical properties of flexible perovskite solar cells. This system can perform fluorescence / photocurrent imaging, bending tests, and wide-field dynamic tests of half-cell structures of flexible perovskite solar cells in the same system. Furthermore, it can utilize fluorescence / photocurrent imaging to monitor the photoelectric performance of flexible perovskite solar cells in-situ at the micro-nano scale, thereby enabling a microscopic understanding of the key issues that exist in the bending process of flexible perovskite solar cells.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A system for in-situ monitoring of the mechanical properties of flexible perovskite solar cells, characterized by comprising a photocurrent detection device, a sample stage, a cell bending mechanism, a microscope, a two-dimensional scanning galvanometer, a laser, an electrically operated folding mirror, and a detector. The sample stage is equipped with a lead dielectric assembly and a cell bending mechanism. During imaging and bending tests, the flexible perovskite solar cell is inverted and positioned on the sample stage within the cell bending mechanism. The lead dielectric assembly includes a positive electrode dielectric and a negative electrode dielectric, with one end of the cell body on the lower side of the flexible perovskite solar cell contacting the positive electrode dielectric and the other end contacting the negative electrode dielectric. The photocurrent detection device... The microscope is equipped with photocurrent probes connected to its side, with one photocurrent probe inserted into the positive electrode medium and the other photocurrent probe inserted into the negative electrode medium. The microscope includes a low-power objective lens and a high-power objective lens. During imaging and bending tests, the motorized folding mirror is raised, and the laser emitted by the laser is injected into the two-dimensional scanning galvanometer. The fluorescence generated by the sample is output by the two-dimensional scanning galvanometer and finally injected into the detector. During the wide-field dynamics test of the half-cell structure, the half-cell structure is inverted on the sample stage and placed in the cell bending mechanism. The motorized folding mirror is lowered, and the laser emitted by the laser is reflected by the motorized folding mirror and then injected into the microscope after passing through the aperture and the beam expander.

[0007] The battery bending mechanism includes a fixed clamping block, a movable clamping block, and a clamping block driving device, wherein the fixed clamping block is fixed on the sample stage, and the movable clamping block is driven to reciprocate by the clamping block driving device.

[0008] A pinhole plate and a filter are sequentially arranged between the two-dimensional scanning galvanometer and the detector.

[0009] During the wide-field dynamics test of the half-cell structure, the laser beam reflected by the motorized folding mirror is first reflected by a high-reflection mirror, and then passes through the aperture and beam expander in sequence before entering the microscope.

[0010] The detector is connected to the single-photon acquisition module via a line, and the single-photon acquisition module is connected to the computer display screen via a line.

[0011] A testing method for a system for in-situ monitoring of the mechanical properties of flexible perovskite solar cells, comprising the following steps in imaging testing:

[0012] Step 1: Place the flexible perovskite solar cell upside down on the sample stage and in the cell bending mechanism. One end of the cell body on the lower side of the flexible perovskite solar cell is in contact with the positive electrode medium, and the other end is in contact with the negative electrode medium.

[0013] Step 2: Take bright-field photographs of the test area of ​​the flexible perovskite solar cell using a low-magnification objective lens in a microscope and mark it. Then, further magnify the perovskite film within the test area using a high-magnification objective lens in a microscope. While observing the grain morphology and selecting pinhole-free and dense films, record the specific location of the grains using bright-field photographs.

[0014] Step 3: Insert the photocurrent probe connected to one side of the photocurrent detection device into the positive electrode medium and the photocurrent probe connected to the other side into the negative electrode medium. At this time, the motorized folding mirror is in the raised state. Then, connect the flexible perovskite solar cell and collect the photocurrent through the photocurrent detection device. The laser is started and emits continuous laser light into the two-dimensional scanning galvanometer. The laser is scanned point by point within the test range through the two-dimensional scanning galvanometer to obtain the photocurrent image within the test range.

[0015] Step 4: Switch the laser from continuous laser to pulsed laser. The fluorescence signal generated by the flexible perovskite solar cell is output by the two-dimensional scanning galvanometer and collected by the detector after passing through the pinhole and filter on the pinhole plate, thereby obtaining fluorescence imaging within the test range.

[0016] A test method for a system for in-situ monitoring of the mechanical properties of flexible perovskite solar cells, wherein the bending test includes the following steps:

[0017] Step 1: Place the flexible perovskite solar cell upside down on the sample stage and in the cell bending mechanism. One end of the cell body on the lower side of the flexible perovskite solar cell is in contact with the positive electrode medium, and the other end is in contact with the negative electrode medium.

[0018] Step 2: Take bright-field photographs of the test area of ​​the flexible perovskite solar cell using a low-magnification objective lens in a microscope and mark it. Then, further magnify the perovskite film within the test area using a high-magnification objective lens in a microscope. While observing the grain morphology and selecting pinhole-free and dense films, record the specific location of the grains using bright-field photographs.

[0019] Step 3: Insert the photocurrent probe connected to one side of the photocurrent detection device into the positive electrode medium and the photocurrent probe connected to the other side into the negative electrode medium. At this time, the motorized folding mirror is in the raised state. Then, connect the flexible perovskite solar cell and collect the photocurrent through the photocurrent detection device. The laser is started and emits continuous laser light into the two-dimensional scanning galvanometer. The laser is scanned point by point within the test range through the two-dimensional scanning galvanometer to obtain the photocurrent image within the test range.

[0020] Step 4: Switch the laser from continuous laser to pulsed laser. The fluorescence signal generated by the flexible perovskite solar cell is output by the two-dimensional scanning galvanometer and collected by the detector after passing through the pinhole and filter on the pinhole plate, thereby obtaining fluorescence imaging within the test range.

[0021] Step 5: Determine the bending radius of the flexible perovskite solar cell based on the thickness of the cell substrate and the thickness of the cell body.

[0022] Step Six: Determine the stress on the flexible perovskite solar cell based on the bending radius determined in Step Five, and then determine the number of bends.

[0023] Step 7: The battery bending mechanism is activated to begin bending the flexible perovskite solar cell. After bending it back and forth a set number of times, steps 1 to 4 are repeated to obtain photocurrent imaging and fluorescence imaging after bending. The results are then compared with the initial photocurrent imaging and initial fluorescence imaging to analyze the cell's dynamic performance.

[0024] A test method for a system for in-situ monitoring of the mechanical properties of flexible perovskite solar cells, comprising the following steps for wide-field dynamic testing of the half-cell structure:

[0025] Step 1: Place the half-cell structure upside down on the sample stage and into the cell bending mechanism. At this time, the electric tilting mirror is in the lowering state.

[0026] Step 2: The pulsed laser emitted by the laser is activated and reflected by the motorized folding mirror, then reflected by a high-reflection mirror, and then passes through the aperture and beam expander in sequence before entering the microscope, thereby obtaining the initial dynamic diagram of the half-cell structure under wide field.

[0027] Step 3: The battery bending mechanism starts to reciprocate bending the half-cell structure. After reciprocating bending a set number of times, Step 2 is repeated to obtain the bending dynamic diagram of the half-cell structure under wide field, and the dynamic performance of the half-cell structure is compared with the initial dynamic diagram to analyze the dynamic performance of the half-cell structure.

[0028] The advantages and positive effects of this invention are as follows:

[0029] 1. The present invention system realizes in-situ monitoring of the mechanical stability of flexible perovskite solar cells. First, it enables fluorescence / photocurrent imaging through system construction. Second, it enables cell bending test and half-cell structure wide-field dynamic test under the same system based on the above fluorescence / photocurrent imaging. Thus, it is possible to understand the key problems existing in the bending process of flexible perovskite solar cells from a microscopic perspective.

[0030] 2. The present invention, through the aforementioned in-situ monitoring, reveals that the increased fluorescence intensity, decreased photocurrent, and slower fluorescence kinetics of the flexible perovskite solar cell after bending are due to the deterioration of the interfacial contact between the perovskite film and the transport layer. Furthermore, after optimizing the interfacial contact between the perovskite film and the transport layer, the optimized cell was tested again, confirming that optimizing the interfacial contact between the perovskite film and the transport layer is beneficial to the mechanical stability of the flexible perovskite solar cell. Simultaneously, it further confirms that in-situ monitoring of the mechanical stability of the flexible perovskite solar cell can be achieved through micro-region fluorescence / photocurrent imaging. Therefore, the present invention is of great significance for further promoting the research and commercial application of flexible perovskite solar cells. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the working state of the system of the present invention. Figure 1 ,

[0032] Figure 2 This is a schematic diagram of the working state of the system of the present invention. Figure 2 ,

[0033] Figure 3 for Figure 1 Enlarged view of point A in the image.

[0034] Figure 4 for Figure 3 A schematic diagram of the battery bending mechanism mounted on the sample stage.

[0035] Figure 5 This is a photocurrent / fluorescence imaging image obtained for the flexible perovskite solar cell targeted in this invention.

[0036] Figure 6 These are photocurrent / fluorescence images of the flexible perovskite solar cell targeted by this invention after 0 and 50 bending cycles.

[0037] Figure 7 These are photocurrent / fluorescence images of the flexible perovskite solar cell targeted by this invention after 500 and 1000 bending cycles.

[0038] Figure 8 This is a wide-field dynamic diagram of pure perovskite thin films under different bending cycles, as presented in this invention.

[0039] Figure 9 This is a wide-field dynamic diagram of the electron transport layer / perovskite thin film / hole transport layer of the half-cell structure under different bending cycles, according to the present invention.

[0040] Figure 10 The images show the photocurrent / fluorescence of the flexible perovskite solar cell after 0 and 50 bending cycles, respectively, following the optimized battery interface of this invention.

[0041] Figure 11 Photocurrent / fluorescence imaging images of the flexible perovskite solar cell after 500 and 1000 bending cycles, after the battery interface has been optimized according to this invention.

[0042] Among them, 1 is a flexible perovskite solar cell, 2 is a photocurrent probe, 3 is a lead dielectric assembly, 4 is a sample stage, 5 is a microscope, 6 is a photocurrent detection device, 7 is a laser, 8 is a high-reflection mirror, 9 is a beam expander, 10 is a scanning lens, 11 is an electric folding mirror, 12 is a two-dimensional scanning galvanometer, 13 is a pinhole plate, 14 is a filter, 15 is a detector, 16 is a single-photon acquisition module, 17 is a computer display screen, 18 is an aperture, 19 is a fixed clamp, 20 is a moving clamp, and 21 is a clamp driving device. Detailed Implementation

[0043] The invention will now be described in further detail with reference to the accompanying drawings.

[0044] like Figures 1-4 As shown, the system of the present invention includes a photocurrent detection device 6, a sample stage 4, a battery bending mechanism, a microscope 5, a two-dimensional scanning galvanometer 12, a laser 7, an electrically operated folding mirror 11, and a detector 15. The sample stage 4 is equipped with a lead dielectric assembly 3 and a battery bending mechanism. The flexible device to be tested (a complete flexible perovskite solar cell 1 or a half-cell structure) is placed in the battery bending mechanism and repeatedly bent a set number of times during subsequent tests. When the flexible device is a flexible perovskite solar cell 1, the flexible perovskite solar cell 1 is inverted and placed on the sample stage 4, i.e., the flexible... The perovskite solar cell 1 has a cell body on the lower side and a cell substrate on the upper side. The lead dielectric assembly 3 includes a positive electrode dielectric and a negative electrode dielectric. One end of the cell body is in contact with the positive electrode dielectric, and the other end is in contact with the negative electrode dielectric. The photocurrent detection device 6 has photocurrent probes 2 connected to both sides, with one photocurrent probe 2 inserted into the positive electrode dielectric and the other photocurrent probe 2 inserted into the negative electrode dielectric. During wide-field dynamic testing of the half-cell structure, the flexible device is a half-cell structure inverted on the sample stage 4 and placed in the cell bending mechanism. The microscope 5 includes a low-power objective lens and a high-power objective lens, and the objective lens can be manually switched, such as... Figure 1 As shown, during the imaging and bending tests, the motorized folding mirror 11 is raised, and the laser emitted by the laser 7 enters the two-dimensional scanning galvanometer 12. The fluorescence generated by the sample is output from the two-dimensional scanning galvanometer 12 and ultimately enters the detector 15. Figure 2 As shown, during the wide-field dynamics test of the half-cell structure, the motorized folding mirror 11 falls down, and the laser emitted by the laser 7 is reflected by the motorized folding mirror 11 and then enters the microscope 5 through the aperture 18 and the beam expander 9 to obtain a magnified light spot.

[0045] In this invention, a 0.03mm thick high-purity copper foil is first used as the positive and negative electrode dielectrics in the lead dielectric assembly 3. Lead wires are then applied to the positive and negative electrodes of the flexible perovskite solar cell 1 (in this embodiment, PET / ITO / SnO2 / PVK / Spiro-MeOTAD / Au). Since the substrate of the flexible cell is PET (polyethylene terephthalate), laser light will refract and scatter when passing through the PET substrate, potentially preventing it from focusing on the focal plane of the perovskite thin film. To avoid this... In this invention, the laser passes through a flexible substrate. The sample is tested upside down, allowing the laser to strike directly from the battery body rather than the flexible substrate. Because of this inverted testing, the photocurrent probe 2 cannot directly contact the positive and negative electrodes. To collect the photocurrent signal, the electrodes of the flexible perovskite solar cell 1 need to be wired. Copper foil serves as the positive and negative electrode dielectric in the lead-wire dielectric assembly 3, respectively attached to the positive and negative electrodes of the battery body. This allows the photocurrent probe 2 to collect the photocurrent signal by contacting the positive and negative electrode dielectrics. Furthermore, the wired treatment does not affect the photocurrent probe 2's ability to collect current information. As shown in the table below, there is almost no difference between the photocurrent probe 2 directly contacting the battery and the probe being attached to the lead-wire area.

[0046] Battery contact mode Current (uA) when halogen lamp is on Dark current (nA) Photocurrent (nA) when laser is on Internal resistance (KΩ) Probe direct contact 145 0.6 210 40 Copper foil lead 120 0.6 200 42

[0047] When this invention is working, as Figure 1 As shown, after the flexible perovskite solar cell 1 sample is fixed on the sample stage 4, the present invention first selects the low-magnification objective lens in the microscope 5 to take a bright-field photograph of the approximate area of ​​the sample and mark it. Then, the high-magnification objective lens in the microscope 5 is used to further magnify the tested perovskite film. While observing the grain morphology and selecting a pinhole-free, dense film, the specific position of the grain is recorded by bright-field photography. Then, the flexible perovskite solar cell 1 is connected and the photocurrent is collected by the photocurrent detection device 6 (a picoammeter in this embodiment). The laser is used to scan the cell point by point through the two-dimensional scanning galvanometer 12 to obtain the photocurrent imaging of the cell micro-area. Then, the laser 7 is switched from continuous light to pulsed laser. The generated fluorescence signal detection light is filtered by the pinhole on the pinhole plate 13 and the long-pass filter 14 to remove stray light and excess laser light, and then collected by the detector 15. In this way, the laser is used to scan the cell point by point through the two-dimensional scanning galvanometer 12 to obtain the fluorescence imaging of the cell micro-area. Figure 5 The left side shows the photocurrent imaging of a flexible perovskite solar cell, and the right side shows the fluorescence imaging. Figure 5 In the photocurrent imaging shown, regions with photocurrent intensity approaching 0 correspond one-to-one with regions of weak fluorescence intensity in the fluorescence imaging. This region is due to excess PbI2 present in the two-step perovskite preparation, while... Figure 5The regions of strong photocurrent intensity in the photocurrent imaging and the regions of strong fluorescence intensity in the fluorescence imaging correspond one-to-one. These are perovskite FAPbI3 grains, obtained through... Figure 5 The fluorescence imaging / photocurrent imaging shown clearly reflects the morphological characteristics of the perovskite thin film grains and the photoelectric information of the battery.

[0048] In this embodiment, the microscope 5, laser 7, two-dimensional scanning galvanometer 12, and motorized folding mirror 11 are all technologies known in the art and are commercially available products. The microscope 5 is an Olympus brand, with an Olympus 10X air objective lens for low magnification and an Olympus 100X oil immersion objective lens for high magnification. The laser 7 is an EGI-D2-40 from NKT Photonics, Germany. The two-dimensional scanning galvanometer 12 is a GCM102 / M from Thorlabs, with two-dimensional directions of x and y. The motorized folding mirror 11 is an LMR1 / M from Thorlabs.

[0049] like Figure 2 As shown, in this embodiment, the battery bending mechanism includes a fixed clamping block 19, a movable clamping block 20, and a clamping block driving device 21. The fixed clamping block 19 is fixed on the sample stage 4, and the movable clamping block 20 is driven to reciprocate linearly by the clamping block driving device 21. The flexible perovskite solar cell 1 or half-cell structure is disposed between the fixed clamping block 19 and the movable clamping block 20, and the reciprocating linear movement of the movable clamping block 20 drives the flexible perovskite solar cell 1 to reciprocate and bend. The clamping block driving device 21 can be selected as a linear driving device such as an electric cylinder as needed. In addition, the laser passes through the optical path of the microscope system and is focused on the flexible perovskite solar cell 1 sample through a high-magnification objective lens. The fixed clamp 19 and the movable clamp 20 horizontally clamp and fix the flexible perovskite solar cell 1 to ensure its imaging stability. The fixed clamp 19 and the movable clamp 20 can be staggered from the positive and negative electrode dielectrics in the lead dielectric assembly 3. For example, the lead dielectric can be located at the end of the sample side and the clamp can be located in the middle of the sample side, so as not to affect the lead contact and sample bending. In addition, the lower side of the clamp driving device 21, clamp and other structures can be insulated as needed to avoid affecting the detection.

[0050] In operation, after obtaining the initial imaging, a bending test can be performed. The clamping block driving device 21 activates to drive the moving clamping block 20 to reciprocate the bending of the flexible perovskite solar cell 1. The bending conditions are a bending radius R = 6 mm and 1000 bending cycles. This condition is chosen because in the flexible perovskite solar cell 1, the thickness of the flexible substrate (125 μm) is much greater than the thickness of the cell body itself (<1 μm). Therefore, according to the single-layer model, when the bending radius is 6 mm, the stress on the flexible perovskite solar cell is 1%. For a stress of 1%, 1000 bending cycles are currently recommended bending conditions for monitoring the mechanical stability of flexible perovskite solar cells. The steps for obtaining fluorescence imaging / photocurrent imaging are repeated on the cell after bending according to the set number of times, thereby obtaining in-situ fluorescence imaging / photocurrent imaging under different bending cycles. Figures 6-7 As shown, the number of bends set in this embodiment includes 50, 500, and 1000 times, determined by... Figures 6-7 Fluorescence and photocurrent imaging before and after bending show that the fluorescence intensity is enhanced and the photocurrent intensity is reduced after bending. This may be because bending leads to a deterioration in the contact between the perovskite film and the transport layer in the flexible perovskite solar cell, resulting in poorer charge extraction, which in turn leads to enhanced fluorescence and reduced photocurrent intensity.

[0051] like Figure 2 As shown, when the present invention performs wide-field dynamics testing of the half-cell structure, the motorized folding mirror 11 is lowered, and the laser beam is irradiated onto the motorized folding mirror 11. The laser beam reflected by the motorized folding mirror 11 is first reflected by a high-reflection mirror 8, and then sequentially passes through the aperture 18 and the beam expander 9 before entering the microscope 5 to achieve the test. Taking the half-cell structures PET / ITO / PVK and PET / ITO / SnO2 / PVK / Spiro-MeOTAD as examples, the present invention changes the laser beam path by switching the motorized folding mirror 11, and adjusts the spot quality by entering the aperture 18 through the high-reflection mirror 8, then amplifies the spot by entering the beam expander 19, and finally enters the microscope optical path through the rear aperture of the microscope 5 to obtain the amplified spot. Thus, the dynamics diagram of the half-cell structure under different bending times under wide field testing is obtained through the microscope's own system.

[0052] Figure 8 The figure shows the kinetics of PET / ITO / PVK under different bending cycles (0, 50, 500, 1000) in a wide field. Figure 8 It can be seen that the kinetics of the half-cell structure PET / ITO / PVK does not change with the increase of bending times.

[0053] Figure 9The figure shows the kinetics of PET / ITO / SnO2 / PVK / Spiro-MeOTAD under different bending cycles (0, 50, 500, and 1000) in a wide field. Figure 9 It can be seen that the kinetics of the half-cell structure PET / ITO / SnO2 / PVK / Spiro-MeOTAD gradually slows down with the increase of bending times. This indicates that the kinetics of the perovskite film itself do not change under bending, but the deterioration of the interfacial contact between the perovskite film and the transport layer leads to the slowdown of kinetic decay.

[0054] To further verify that the deterioration of the interfacial contact between the perovskite thin film and the transport layer is the cause of the enhanced fluorescence, reduced photocurrent intensity, and slower kinetic decay of the flexible perovskite solar cell 1, this embodiment of the invention can optimize the interfacial contact between the electron transport layer and the perovskite thin film to improve the flexible perovskite solar cell. Then, confocal fluorescence / photocurrent scanning imaging is used to perform fluorescence / photocurrent imaging of the flexible perovskite solar cell 1 at different bending cycles. Figures 10-11 The images show fluorescence / photocurrent imaging of the same region of the same cell in a flexible perovskite solar cell with optimized interface contact 1 under different bending cycles. The results show that within 500 bending cycles, the fluorescence intensity and photocurrent values ​​do not change significantly. After 1000 bending cycles, the fluorescence / photocurrent imaging shows a slight increase in fluorescence intensity and a decrease in photocurrent values ​​in some areas, compared to... Figure 6 The fluorescence / photocurrent imaging of the flexible perovskite solar cell showed significant changes after 50 bends. However, the fluorescence / photocurrent imaging of the flexible perovskite solar cell with optimized interface contact only showed significant changes after 1000 bends. This further proves that the deterioration of the interface contact between the perovskite film and the transport layer is the cause of the enhanced fluorescence, reduced photocurrent intensity, and slower kinetic decay of the flexible perovskite solar cell. Therefore, modifying and optimizing the interface contact between the transport layer and the perovskite film can further improve the mechanical stability of the flexible perovskite solar cell.

[0055] like Figure 1 As shown, in this embodiment, the detector 15 is connected to the single-photon acquisition module 16 via a circuit, and the single-photon acquisition module 16 is connected to the computer display screen 17 via a circuit. The image is converted by the single-photon acquisition module 16 and then displayed on the computer display screen 17. In this embodiment, the detector 15 is an MPD, PicoQuant, Germany device, and the single-photon acquisition module 16 is a time-correlated single-photon acquisition card (TCSPC), all of which are commercially available products.

[0056] The working principle of this invention is as follows:

[0057] This invention includes three testing methods: imaging testing, bending testing, and wide-field dynamics testing of half-cell structures. The imaging testing includes the following steps:

[0058] Step 1: The flexible perovskite solar cell 1 is placed upside down on the sample stage 4 and placed in the cell bending mechanism. One end of the cell body on the lower side of the flexible perovskite solar cell 1 is in contact with the positive electrode medium and the other end is in contact with the negative electrode medium.

[0059] Step 2: Take a bright-field photograph of the test area of ​​the flexible perovskite solar cell 1 through the low-magnification objective lens of microscope 5 and mark it. Then, take a high-magnification photograph of the perovskite film within the test area through the high-magnification objective lens of microscope 5. While observing the grain morphology and selecting a pinhole-free and dense film, record the specific location of the grains through bright-field photography.

[0060] Step 3: Insert the photocurrent probe 2 connected to one side of the photocurrent detection device 6 into the positive electrode medium, and insert the photocurrent probe 2 connected to the other side into the negative electrode medium. At this time, the motorized folding mirror 11 is in the raised state. Connect the flexible perovskite solar cell 1 and collect the photocurrent through the photocurrent detection device 6. The laser 7 is started and the continuous laser emitted (wavelength 405nm in this embodiment) is injected into the two-dimensional scanning galvanometer 12. The two-dimensional scanning galvanometer 12 realizes the point-by-point scanning of the laser on the cell, thereby obtaining the photocurrent imaging of the test range.

[0061] Step 4: Switch the laser 7 from continuous laser to pulsed laser. The fluorescence signal generated by the flexible perovskite solar cell 1 is output by the two-dimensional scanning galvanometer 12 and passes through the pinhole on the pinhole plate 13 and the long-pass filter 14 to filter out stray light and excess laser light. Then it is collected by the detector 15. In this way, the laser is scanned point by point on the cell by the two-dimensional scanning galvanometer 12, thereby obtaining fluorescence imaging of the test range.

[0062] The bending test includes the following steps:

[0063] Steps one through four are used to obtain initial photocurrent imaging and initial fluorescence imaging, which are the same as the imaging test steps.

[0064] Step 5: Determine the bending radius of the flexible perovskite solar cell 1 based on the substrate thickness and cell body thickness:

[0065] In this embodiment, since the thickness of the flexible cell substrate (125 μm) in the flexible perovskite solar cell 1 is much greater than the thickness of the cell body itself (<1 μm), the bending radius is calculated to be 6 mm based on the single-layer model.

[0066] Step Six: Determine the stress on the flexible perovskite solar cell 1 based on the bending radius determined in Step Five, and then determine the number of bends:

[0067] When the bending radius of the cell is 6 mm, the stress on the flexible perovskite solar cell 1 is 1%. For a stress of 1%, 1000 bending cycles are currently the recommended bending condition for monitoring the mechanical stability of flexible perovskite solar cells.

[0068] Step 7: The battery bending mechanism is started to bend the flexible perovskite solar cell 1. After bending it back and forth a set number of times, steps 1 to 4 are repeated to obtain photocurrent imaging and fluorescence imaging after bending. The battery dynamic performance is then compared with the initial photocurrent imaging and initial fluorescence imaging.

[0069] Wide-field dynamics testing of a half-cell structure includes the following steps:

[0070] Step 1: Place the half-cell structure upside down on the sample stage 4 and in the cell bending mechanism. At this time, the electric tilting mirror 11 is in the lowering state.

[0071] Step 2: The pulsed laser emitted by the laser 7 is activated and has a wavelength of 405nm. After being reflected by the motorized folding mirror 11, it is first reflected by a high-reflection mirror 8, and then passes through the aperture 18 and the beam expander 9 in sequence before entering the microscope 5 to obtain a magnified spot, thereby obtaining the initial dynamic diagram of the half-cell structure under wide field.

[0072] Step 3: The battery bending mechanism starts to reciprocate bending the half-cell structure. After reciprocating bending a set number of times, Step 2 is repeated to obtain the bending dynamic diagram of the half-cell structure under wide field, and the dynamic performance of the half-cell structure is compared with the initial dynamic diagram to analyze the dynamic performance of the half-cell structure.

Claims

1. A system for in-situ monitoring of the mechanical properties of flexible perovskite solar cells, characterized in that: The system includes a photocurrent detection device (6), a sample stage (4), a battery bending mechanism, a microscope (5), a two-dimensional scanning galvanometer (12), a laser (7), an electric folding mirror (11), and a detector (15). The sample stage (4) is equipped with a lead dielectric assembly (3) and a battery bending mechanism. During imaging and bending tests, the flexible perovskite solar cell (1) is inverted and placed on the sample stage (4) and within the battery bending mechanism. The lead dielectric assembly (3) includes a positive electrode dielectric and a negative electrode dielectric. One end of the battery body on the lower side of the flexible perovskite solar cell (1) is in contact with the positive electrode dielectric, and the other end is in contact with the negative electrode dielectric. The photocurrent detection device (6) is connected to photocurrent probes (2) on both sides, and one of them is a photoelectric sensor. The current probe (2) is inserted into the positive electrode medium, and another photocurrent probe (2) is inserted into the negative electrode medium. The microscope (5) includes a low-power objective lens and a high-power objective lens. During imaging and bending tests, the motorized folding mirror (11) is raised, and the laser emitted by the laser (7) is injected into the two-dimensional scanning galvanometer (12). The fluorescence generated by the sample is output by the two-dimensional scanning galvanometer (12) and finally injected into the detector (15). During the wide-field dynamics test of the half-cell structure, the half-cell structure is inverted on the sample stage (4) and placed in the battery bending mechanism. The motorized folding mirror (11) is lowered, and the laser emitted by the laser (7) is reflected by the motorized folding mirror (11) and injected into the microscope (5) after passing through the aperture (18) and the beam expander (9).

2. The system for in-situ monitoring of the mechanical properties of flexible perovskite solar cells according to claim 1, characterized in that: The battery bending mechanism includes a fixed clamping block (19), a movable clamping block (20), and a clamping block driving device (21), wherein the fixed clamping block (19) is fixed on the sample stage (4), and the movable clamping block (20) is driven to reciprocate by the clamping block driving device (21).

3. The system for in-situ monitoring of the mechanical properties of flexible perovskite solar cells according to claim 1, characterized in that: A pinhole plate (13) and a filter (14) are sequentially disposed between the two-dimensional scanning galvanometer (12) and the detector (15).

4. The system for in-situ monitoring of the mechanical properties of flexible perovskite solar cells according to claim 1, characterized in that: During the wide-field dynamics test of the half-cell structure, the laser beam reflected by the electric folding mirror (11) is first reflected by a high-reflection mirror (8), and then passes through the aperture (18) and the beam expander (9) in sequence before entering the microscope (5).

5. The system for in-situ monitoring of the mechanical properties of flexible perovskite solar cells according to claim 1, characterized in that: The detector (15) is connected to the single-photon acquisition module (16) via a line, and the single-photon acquisition module (16) is connected to the computer display screen (17) via a line.

6. A testing method for a system for in-situ monitoring of the mechanical properties of flexible perovskite solar cells according to claim 1, characterized in that: Imaging tests include the following steps: Step 1: Place the flexible perovskite solar cell (1) upside down on the sample stage (4) and in the cell bending mechanism. One end of the cell body on the lower side of the flexible perovskite solar cell (1) is in contact with the positive electrode medium and the other end is in contact with the negative electrode medium. Step 2: Take a bright-field photograph of the test area of ​​the flexible perovskite solar cell (1) through the low-power objective lens in the microscope (5) and mark it. Then, take a high-power objective lens in the microscope (5) to further magnify the perovskite film within the test area. While observing the grain morphology and selecting a pinhole-free and dense film, record the specific position of the grains through bright-field photography. Step 3: Insert the photocurrent probe (2) connected to one side of the photocurrent detection device (6) into the positive electrode medium and the photocurrent probe (2) connected to the other side into the negative electrode medium. At this time, the electric folding mirror (11) is in the raised state. Then connect the flexible perovskite solar cell (1) and collect the photocurrent through the photocurrent detection device (6). The laser (7) is started and emits continuous laser light into the two-dimensional scanning galvanometer (12). The laser is scanned point by point within the test range through the two-dimensional scanning galvanometer (12) to obtain the photocurrent image within the test range. Step 4: Switch the laser (7) from continuous laser to pulsed laser. The fluorescence signal generated by the flexible perovskite solar cell (1) is output by the two-dimensional scanning galvanometer (12) and collected by the detector (15) after passing through the pinhole on the pinhole plate (13) and the filter (14), thereby obtaining fluorescence imaging within the test range.

7. A testing method for a system for in-situ monitoring of the mechanical properties of flexible perovskite solar cells according to claim 1, characterized in that: The bending test includes the following steps: Step 1: Place the flexible perovskite solar cell (1) upside down on the sample stage (4) and in the cell bending mechanism. One end of the cell body on the lower side of the flexible perovskite solar cell (1) is in contact with the positive electrode medium and the other end is in contact with the negative electrode medium. Step 2: Take a bright-field photograph of the test area of ​​the flexible perovskite solar cell (1) through the low-power objective lens in the microscope (5) and mark it. Then, take a high-power objective lens in the microscope (5) to further magnify the perovskite film within the test area. While observing the grain morphology and selecting a pinhole-free and dense film, record the specific position of the grains through bright-field photography. Step 3: Insert the photocurrent probe (2) connected to one side of the photocurrent detection device (6) into the positive electrode medium and the photocurrent probe (2) connected to the other side into the negative electrode medium. At this time, the electric folding mirror (11) is in the raised state. Then connect the flexible perovskite solar cell (1) and collect the photocurrent through the photocurrent detection device (6). The laser (7) is started and emits continuous laser light into the two-dimensional scanning galvanometer (12). The laser is scanned point by point within the test range through the two-dimensional scanning galvanometer (12) to obtain the photocurrent image within the test range. Step 4: Switch the laser (7) from continuous laser to pulsed laser. The fluorescence signal generated by the flexible perovskite solar cell (1) is output by the two-dimensional scanning galvanometer (12) and collected by the detector (15) after passing through the pinhole on the pinhole plate (13) and the filter (14), thereby obtaining fluorescence imaging within the test range. Step 5: Determine the bending radius of the flexible perovskite solar cell (1) based on the thickness of the cell substrate and the thickness of the cell body; Step 6: Determine the stress on the flexible perovskite solar cell (1) based on the bending radius determined in Step 5, and then determine the number of bends. Step 7: The battery bending mechanism is started to bend the flexible perovskite solar cell (1). After bending back and forth a set number of times, steps 1 to 4 are repeated to obtain photocurrent imaging and fluorescence imaging after bending. The battery dynamic performance is then compared with the initial photocurrent imaging and initial fluorescence imaging.

8. A testing method for a system for in-situ monitoring of the mechanical properties of flexible perovskite solar cells according to claim 1, characterized in that: Wide-field dynamics testing of a half-cell structure includes the following steps: Step 1: Place the half-cell structure upside down on the sample stage (4) and in the battery bending mechanism. At this time, the electric tilting mirror (11) is in the lowering state. Step 2: The laser (7) is started and the pulsed laser emitted is reflected by the electric folding mirror (11), then reflected by a high-reflection mirror (8), and then passed through the aperture (18) and the beam expander (9) in sequence into the microscope (5), thereby obtaining the initial dynamic diagram of the half-cell structure in the wide field. Step 3: The battery bending mechanism starts to reciprocate bending the half-cell structure. After reciprocating bending a set number of times, Step 2 is repeated to obtain the bending dynamic diagram of the half-cell structure under wide field, and the dynamic performance of the half-cell structure is compared with the initial dynamic diagram to analyze the dynamic performance of the half-cell structure.

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