Rapid photocurrent imaging test device, system and method

Abstract

The invention discloses a rapid photocurrent imaging test device, system and method. The device comprises a beam expander (2), a galvanometer (3), a field lens (4), a data collector (6), a synchronizing signal generator (7) and a controller (8). Wherein the beam expander (2) is used for expanding the diameter of a laser beam emitted by the laser light source (1), so that the laser beam is focused through the field lens (4) to obtain a light spot with a smaller diameter; the synchronizing signal generator (7) is used for receiving a control signal of the controller (8) and generating a synchronizing signal for controlling the movement of the galvanometer (3) and data acquisition; the galvanometer (3) is used for controlling the rotating angle of the reflecting mirror according to the synchronizing signal and adjusting the emitting direction of the laser beam; the field lens (4) is used for focusing and coupling the laser beam to obtain a laser spot with a smaller focus diameter; and the data collector (6) is used for collecting light current / light voltage signals of the to-be-detected sample according to the synchronizing signal. According to the invention, the problems that the moving speed is low, the required time is long and the occupied area of the testing device and system is greatly reduced when the sample to be tested is moved by using an electric control moving table can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of solar cell testing, in particular to a rapid photocurrent imaging testing device, system and method. BACKGROUND

[0002] Solar cell photocurrent imaging is a technology for detecting and analyzing the performance of solar cells using optical means. This technology can accurately image two-dimensional defects of solar cells, such as dislocations, cracks, and short-circuit regions, which is of great significance for quality control and yield improvement in the production process of solar cells.

[0003] The main principle of using solar cell photocurrent imaging to image two-dimensional defects of solar cells is as follows: a specific wavelength of laser is used to irradiate the solar cell sample, and under the action of the laser, the solar cell sample generates photocurrent. The photocurrent signal is introduced to the current source table through the probe, and then read out by software. During the scanning process, the laser spot is controlled to move on the sample surface, and the current value corresponding to each spot position is recorded by software, so as to draw a photocurrent imaging map on the software to display the current distribution of the solar cell sample. By analyzing the distribution of photocurrent, the internal microstructure and defects of the solar cell can be clearly distinguished, thereby providing a basis for in-depth study of the performance and damage mechanism of the solar cell. This non-contact and accurate measurement of solar cells is an important detection and analysis technology for solar cells, and plays an irreplaceable role in improving the quality and performance of solar cells.

[0004] When using the above photocurrent imaging testing technology with an electrically controlled displacement table, the photocurrent imaging mapping test function is realized by moving the position of the solar cell sample or moving the position of the light source. However, there are the following technical deficiencies: first, the electric displacement table moves together with the sample during the movement, the movement speed is slow, and the testing time is long. Second, the resolution of the test mapping depends on the movement resolution of the electrically controlled displacement table. Due to the limitation of resolution, the larger the area of the electrically controlled displacement table, the lower the movement resolution. Third, the test device or system needs to occupy a large area of testing site when using the electrically controlled displacement table to move the position of the sample for testing. For example, when using the electrically controlled displacement table to move the position of the sample for testing, the position of the sample needs to be changed from time to time, and the actual area of the testing site occupied is four times the area of the testing region.

[0005] Furthermore, existing technologies also employ photocurrent imaging testing using controlled galvanometers. However, this method has significant drawbacks. The galvanometer-controlled method only allows control of the laser spot. After moving the laser spot to a position to test the electrical signal of the solar cell sample at that location, the spot must be moved to a new position for further testing. Therefore, this method of using a galvanometer to control a moving laser spot to test the photoelectric signal at a corresponding location on the solar cell sample is slow in both movement and testing speeds, requires a long testing time, and thus has very low testing efficiency. Summary of the Invention

[0006] In view of this, the main objective of this application is to provide a rapid photocurrent imaging testing device, system and method, which aims to address the problems of slow movement speed and long time required when moving the sample under test using an electronically controlled moving stage during photocurrent testing, and to significantly reduce the footprint of the testing device and system.

[0007] To achieve the above objectives, this application adopts the following technical solution:

[0008] A rapid photocurrent imaging testing device includes a laser source 1 and a sample to be tested; characterized in that it further includes a beam expander 2, a galvanometer 3, a field lens 4, a data acquisition unit 6, a synchronization signal generator 7, and a controller 8; wherein:

[0009] The laser source 1, beam expander 2, galvanometer 3, field mirror 4, and sample under test are sequentially connected through a laser optical path; the controller 8 is bidirectionally electrically connected to the data acquisition unit 6 and the synchronization signal generator 7; the synchronization signal generator 7 is unidirectionally electrically connected to the galvanometer 3 and the data acquisition unit 6; the signal output terminal of the sample under test is electrically connected to the data acquisition unit 6.

[0010] The beam expander 2 is used to enlarge the diameter of the laser beam emitted by the laser source 1, so that the laser beam is focused by the field mirror 4 to obtain a smaller diameter spot.

[0011] The synchronization signal generator 7 is used to receive the control signal from the controller 8 to generate a synchronization signal for controlling the movement of the galvanometer 3 and for the data acquisition device 6 to perform data acquisition.

[0012] The galvanometer 3 is used to control the rotation angle of the reflector according to the synchronization signal, thereby adjusting the emission direction of the laser beam;

[0013] The field mirror 4 is used to focus the laser beam and couple it to obtain a laser spot with a smaller focal diameter;

[0014] Data acquisition unit 6 is used to collect photocurrent / photovoltage signals of the sample under test according to the synchronization signal.

[0015] The laser light source 1 is a laser capable of emitting one wavelength or multiple wavelengths.

[0016] The galvanometer 3 is a light device comprising at least one single / multi-axis mirror or a light device using a piezoelectric deflection mirror.

[0017] The field lens 4 is used to make the laser beams at different positions have the same working distance.

[0018] The field lens 4 is at least one lens or a lens group.

[0019] The sample to be tested is placed on the sample stage 5, and the output signal end of the sample to be tested is electrically connected with the signal acquisition end of the data collector 6.

[0020] The synchronous signal generator 7 sends synchronous signals to the galvanometer 3 and the data collector 6 in a synchronous circuit mode, so that the galvanometer 3 deflects to change the different positions of the laser spot on the sample to be tested, and the data collector 6 synchronously collects the current / voltage signals, and the test process does not need to stop.

[0021] The controller 8 is used to control the synchronous signal generator 7 to output the synchronous signals for moving the laser spot of the galvanometer 3 and synchronously collecting the current / voltage signals of the data collector 6.

[0022] A test system comprising the rapid photoelectric current imaging test device further comprises an optical path switching device added between the laser light source 1 and the beam expander 2, which is used to switch between multiple wavelength lasers.

[0023] A rapid photoelectric current imaging test method comprises the following steps.

[0024] The sample to be tested is placed on the sample stage, and the signal input end of the data collector 6 is connected, and the rapid photoelectric current imaging test device is started;

[0025] The controller 8 sends a synchronous test signal to the synchronous signal generator 7, the synchronous signal generator 7 generates a synchronous signal, and sends the synchronous signal to the galvanometer 3 and the data collector 6.

[0026] The galvanometer 3 continuously adjusts the deflection angle of the mirror under the control of the synchronous signal, so that the laser spot moves; at the same time, the data collector 6 is started to collect the electrical signals of the sample to be tested.

[0027] Compared with the prior art, the rapid photoelectric current imaging test device, system and method have the following beneficial effects.

[0028] The technical scheme of the present application expands the laser beam, then couples the laser beam to the sample table through a galvanometer and a field lens, adjusts the spot position through the galvanometer, and realizes photoelectric current imaging test under the condition that the sample position is static. The galvanometer adjustment and sample signal acquisition can be triggered synchronously, the moving scanning of the spot is synchronized with the photoelectric signal test, the spot movement during the test does not need to stop and then acquire the signal, and the speed of the photoelectric current imaging scanning can be greatly improved. The problems of slow movement speed, long required time, and large floor area of the test device and system when the electrically controlled moving table is used to move the sample to be tested are solved. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The figure is a schematic diagram of the architecture of the fast photoelectric current imaging test device of the embodiment of the present application.

[0030] Figure 2 The figure is a data state diagram of the embodiment of the present application for testing one row of 1000 points at a sampling frequency of 5 Hz.

[0031] Figure 3 The figure is a data state diagram of the embodiment of the present application for testing one row of 2000 points at a sampling frequency of 5 Hz. DETAILED DESCRIPTION

[0032] The technical solutions in the embodiments of the present application will be described clearly below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art belong to the scope of protection of the present application.

[0033] The terms "first", "second", and the like in the specification and claims of the present application are used to distinguish similar objects, and are not used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than those illustrated or described herein, and the objects distinguished by "first", "second", and the like are generally of a kind, and are not limited to the number of objects, for example, the first object can be one or more. In addition, "and / or" in the specification and claims means at least one of the connected objects, and the character " / ", generally indicates that the objects before and after are in an "or" relationship.

[0034] Figure 1 The figure is a schematic diagram of the architecture of the fast photoelectric current imaging test device of the embodiment of the present application.

[0035] As Figure 1As shown, the rapid photoelectric current imaging test device mainly comprises a laser light source 1, a beam expander 2, a galvanometer 3, a field lens 4, a sample stage 5, a data collector 6, a synchronous signal generator 7 and a controller 8.

[0036] The laser light source 1, the beam expander 2, the galvanometer 3, the field lens 4 and the to-be-tested solar cell sample (placed on the sample stage 5) are sequentially connected through a laser light path. The controller 8 is bidirectionally connected with the data collector 6 and the synchronous signal generator 7; the synchronous signal generator 7 is unidirectionally connected with the galvanometer 3 and the data collector 6; the to-be-tested solar cell sample is placed on the sample stage 5, and a signal output end of the to-be-tested solar cell sample is electrically connected with the data collector 6.

[0037] The laser light source 1 is a laser capable of emitting a wavelength or multiple wavelengths, and can emit laser light of different wavelengths according to the test requirement. For example, the laser wavelength can be 405 nm, 532 nm, 635 nm, 808 nm, etc., and one or more different laser wavelengths can be selected according to the test requirement.

[0038] The beam expander 2 is used to expand the diameter of the laser beam emitted by the laser light source 1, which is beneficial to the focusing of the laser beam by the field lens 4 to obtain a smaller-diameter light spot, so as to improve the resolution of the photoelectric current imaging.

[0039] The galvanometer 3 is used to control the emission direction of the laser beam by rotating the angle of the mirror thereof.

[0040] Here, the galvanometer 3 can specifically be an optical device containing at least one single-axis / multi-axis mirror, or can be an optical device using a piezoelectric deflection mirror.

[0041] The field lens 4 is used to focus the laser beam to obtain a smaller-diameter laser light spot, and can make the focusing working distance of the light beams at different positions consistent.

[0042] Here, the field lens 4 is at least one lens or a lens group.

[0043] The sample stage 5 is used to place the to-be-tested sample, such as a solar cell sample. The output signal end of the to-be-tested sample is electrically connected with the signal collection end of the data collector 6, so as to transmit the output signal of the to-be-tested sample to the data collector 6.

[0044] Data collector 6 is used for collecting the photocurrent / voltage signals, and is also used for collecting the photocurrent / voltage signals of the solar cell sample under test at a controllable speed under the control of the synchronization signals sent by the synchronization signal generator 7, and making the collecting speed of the photocurrent / voltage signals keep in synchronization with the collecting of the photocurrent / voltage signals by the moving distance of the light spot under the control of the galvanometer 3. The data collector 6 can also be used for feeding back the collecting status of the photocurrent / voltage signals of the sample under test to the controller 8 in real time, and sending the control signals to the synchronization signal generator 7 to control the collecting speed of the above-mentioned signals by the synchronization signals, so as to realize the synchronous collecting of the photocurrent / voltage signals of the sample under test at different light spot moving distances.

[0045] The synchronization signal generator 7 is used for generating the synchronization signals for controlling the movement of the galvanometer 3 and the data collecting. The synchronization signal generator 7 can be a multi-channel arbitrary function signal generator, which controls the movement of the galvanometer 3 by outputting the voltage, and starts the data collecting of the sample under test by outputting the synchronization signals to the data collector 6.

[0046] Here, the data collecting of the sample under test includes but is not limited to the size of the photocurrent / voltage signals at the same position of the sample under test, and also includes the size of the photocurrent / voltage signals at different positions of the sample under test changed by the galvanometer 3 and the field lens 4.

[0047] The controller 8 is used for controlling the output of the synchronization signal generator 7 to make the movement of the light spot of the galvanometer 3 and the collecting of the current signals, and then making the two-dimensional scanning light signal graph.

[0048] In the above-mentioned embodiment of the present application, the galvanometer 4 can be used for realizing the photocurrent imaging test of the sample under test (including but not limited to the solar cell and other photoelectric devices) in the static state. However, it is not limited to the photocurrent imaging test, and can also be used for the spectral responsivity imaging test, the quantum efficiency imaging test, and the single-wavelength volt-ampere characteristic test, etc.

[0049] Preferably, in the above-mentioned embodiment of the present application, the optical path switching device can be added between the laser light source 1 and the beam expander 2 to form a fast photocurrent imaging test system, so as to realize the switching selection among the multiple wavelength lasers.

[0050] Furthermore, in the embodiments of the present invention, the synchronization signal generator 7 employs a synchronization circuit to send synchronization signals to the galvanometer 3 and the data acquisition unit 6, causing the galvanometer 3 to deflect and change the position of the laser spot on the sample under test. Simultaneously, the data acquisition unit 6 synchronously acquires electrical signals such as current / voltage. The position of the laser spot does not need to be interrupted during the test, thus greatly reducing the time of photocurrent imaging test, as well as the test time of spectral responsivity imaging test, quantum efficiency imaging test, etc., thereby improving the test efficiency.

[0051] In a typical embodiment, the synchronization signal emitted by the synchronization signal generator 7 is a triangular wave signal (the voltage value is constantly changing, and for the galvanometer 3, the corresponding control action is to deflect the reflector at different angles). The galvanometer 3 can make the laser spot start to move, and a signal acquisition command is output synchronously. The data acquisition unit 6 then begins to acquire the electrical signal emitted by the sample under test.

[0052] When continuously acquiring electrical signals, different data acquisition time intervals correspond to different laser spot positions. The number of acquired values / data points can be calculated based on the set time intervals, corresponding to different laser spot positions. The total length swept by the laser spot (e.g., 100mm) divided by the number of acquired values / data points (e.g., 1000 points, reference) is calculated. Figure 2 ) or 2000 points (reference) Figure 3 By scanning the rows, photocurrent signals at intervals of 0.05 mm can be obtained. After the row scan is completed, the image can be moved column by column to obtain a two-dimensional photocurrent / photovoltage signal imaging test pattern.

[0053] Assuming a mobile station is used for testing, testing one point takes approximately 0.5 seconds (s). If 1000 × 1000 points need to be tested (refer to...),... Figure 2 The required testing time would be 138 hours. However, using the galvanometer testing method of this invention, the fastest testing speed can reach 100Hz, meaning that the testing time for each row only requires 0.01s, and testing 1000 rows only takes 10s. Even if some samples have a slower response speed, the testing speed can still reach 5Hz, so the testing time required to complete 1000 rows is 200s.

[0054] It can be seen that, by expanding the laser beam, coupling it to the sample stage through the galvanometer and field lens, and adjusting the spot position through the galvanometer, the photocurrent imaging test can be performed when the sample position is stationary. The galvanometer adjustment and sample signal acquisition can be triggered synchronously to realize the line movement scanning of the spot and the synchronous test of the photoelectric signal. In this way, the spot movement does not need to be stopped before the signal is collected, which can greatly improve the speed of the photocurrent imaging scanning, and solve the problems of slow movement speed, long test time, and large area occupied by the test device and system when the electrically controlled moving table is used to move the sample to be tested.

[0055] Based on the same inventive concept, the application further provides a test system comprising the fast photocurrent imaging test device, and the test system further comprises an optical path switching device added between the laser light source 1 and the beam expander 2, which is used to switch and select between multiple wavelength lasers.

[0056] The embodiments of the application are described above in combination with the drawings, but the application is not limited to the specific embodiments described above, which are only illustrative and not restrictive. Those skilled in the art can make many forms under the inspiration of the application without departing from the scope of the application and the protection scope of the claims.

Claims

1. A rapid photocurrent imaging testing device, comprising a laser source (1) and a sample to be tested; characterized in that, It also includes a beam expander (2), a galvanometer (3), a field lens (4), a data acquisition unit (6), a synchronization signal generator (7), and a controller (8); wherein: The laser source (1), beam expander (2), galvanometer (3), field mirror (4), and sample to be tested are connected sequentially through a laser optical path; the controller (8) is bidirectionally electrically connected to the data acquisition unit (6) and the synchronization signal generator (7); the synchronization signal generator (7) is unidirectionally electrically connected to the galvanometer (3) and the data acquisition unit (6); the signal output terminal of the sample to be tested is electrically connected to the data acquisition unit (6). The beam expander (2) is used to expand the diameter of the laser beam emitted by the laser source (1) so that the laser beam is focused by the field lens (4) to obtain a smaller diameter spot. The synchronization signal generator (7) is used to receive the control signal from the controller (8) to generate a synchronization signal for controlling the movement of the galvanometer (3) and for the data acquisition device (6) to perform data acquisition. The galvanometer (3) is used to control the rotation angle of the reflector according to the synchronization signal and adjust the emission direction of the laser beam; The field mirror (4) is used to focus the laser beam and couple it to obtain a laser spot with a smaller focal diameter; The data acquisition unit (6) is used to collect photocurrent / photovoltage signals of the sample under test according to the synchronization signal.

2. The fast photocurrent imaging testing device according to claim 1, characterized in that, The laser source (1) is a laser that can emit one wavelength or / and multiple wavelengths.

3. The fast photocurrent imaging testing device according to claim 1, characterized in that, The galvanometer (3) is an optical device that includes at least one single-axis / multi-axis reflector, or an optical device that uses a piezoelectric deflector.

4. The fast photocurrent imaging testing device according to claim 1, characterized in that, The field lens (4) is also used to make the laser beams at different positions focus at the same working distance.

5. The fast photocurrent imaging testing device according to claim 1 or 4, characterized in that, The field lens (4) is at least one lens or a group of lenses.

6. The fast photocurrent imaging testing device according to claim 1, characterized in that, The sample to be tested is placed on the sample stage (5), and the output signal terminal of the sample to be tested is electrically connected to the signal acquisition terminal of the data acquisition device (6).

7. The fast photocurrent imaging testing device according to claim 1, characterized in that, The synchronization signal generator (7) uses a synchronization circuit to send a synchronization signal to the galvanometer (3) and the data acquisition unit (6), causing the galvanometer (3) to deflect and change the position of the laser spot on the sample to be tested, while the data acquisition unit (6) synchronously acquires current / voltage signals.

8. The fast photocurrent imaging testing device according to claim 1, characterized in that, The controller (8) is used to control the synchronous signal generator (7) to output a synchronous electrical signal that enables the laser spot of the galvanometer (3) to move and the data acquisition unit (6) to collect current / voltage signals synchronously. The position of the laser spot does not need to be paused during the test.

9. A test system comprising the fast photocurrent imaging test apparatus according to any one of claims 1 to 8, characterized in that, It also includes an optical path switching device added between the laser source (1) and the beam expander (2) to enable switching between lasers of multiple wavelengths.

10. A method for rapid photocurrent imaging testing, characterized in that, Includes the following steps: Place the sample to be tested on the sample stage and connect the signal input terminal of the data acquisition unit (6) to start the rapid photocurrent imaging test device; The controller 8 sends a synchronization test signal to the synchronization signal generator (7), the synchronization signal generator (7) generates a synchronization signal, and sends the synchronization signal to the galvanometer (3) and the data acquisition unit (6); The galvanometer (3) continuously adjusts the deflection angle of the reflector under the control of the synchronization signal, causing the laser spot to move; at the same time, the data acquisition device (6) is started to collect the electrical signal of the sample to be tested.

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