Detection device and diagnosis method for lattice quality of sub-cells in multi-junction solar cell

Abstract

The invention discloses a device for detecting the lattice quality of a sub-cell in a multi-junction solar cell. The device comprises a copper probe station module, an optical integrating sphere, a high-precision spectrometer, an optical fiber, a power meter and a processor, one side of the optical integrating sphere is provided with a circular opening, the copper probe station module is arranged at the circular opening of the optical integrating sphere, and the power meter is connected with the copper probe station module; the output end of the optical integrating sphere is connected with one end of the optical fiber, and the other end of the optical fiber is connected with the high-precision spectrometer. The detection device can comprehensively evaluate the lattice growth quality and the global lattice quality.

Description

Technical Field

[0001] The present invention relates to the field of solar cell chip testing, and more particularly to a device and method for detecting the lattice quality of sub-cells within a multi-junction solar cell. Background Art

[0002] Multi-junction solar cells are high-end semiconductor photovoltaic chips with many advantages, including ultra-high efficiency, lightweight, and radiation-resistant properties. They are the preferred devices for aerospace applications. With the continuous advancement of semiconductor manufacturing processes, multi-junction solar cell chips (MJSCs) with various structures or process types have been developed, such as InGaP / GaAs / Ge triple junction (LM-3JSC) and InGaP / GaAs / InGaAs triple junction (IMM-3JSC). In recent years, in order to achieve higher conversion efficiency or improve the radiation resistance of devices, the industry has attempted to introduce fine heteroepitaxial structures such as quantum wells, quantum dots, distributed Bragg reflectors (DBRs), and graded buffer layers into the current-limiting junction of multi-junction solar cells. However, with the increase in the number of sub-cells and the introduction of fine structures such as quantum wells and quantum dots, especially when there is lattice mismatch between the materials in the epitaxial layer, more lattice defects will be introduced into the active region, which in turn become new carrier recombination centers, causing varying degrees of degradation in the photoelectric properties of the sub-cells. Therefore, in the structural design and process iteration of multi-junction solar cells, it is necessary to continuously and effectively evaluate the lattice quality, defect density, etc. of the active area inside the actual chip.

[0003] Existing characterization techniques, such as X-ray diffraction (XRD) and X-ray reciprocal space mapping (RSM), can measure the relaxation and stress distribution of the lattice within the stack, but they cannot specifically quantify the lattice growth quality and defect distribution of each epitaxial layer. Field-emission scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM) can characterize defect distribution in localized regions, such as the device's surface and interfaces, but require chip slicing and cannot quantify lattice quality globally. Therefore, for high-end multi-junction solar cell chips (especially those with complex and sophisticated designs), there is an urgent need to develop an effective, non-invasive, and highly accurate diagnostic and assessment method that can characterize the material growth quality of all sub-cell active regions.

[0004] The prior art discloses a device and method for testing the performance of blue-light LED-excited phosphors. This method provides a device and method for testing the performance of blue-light LED-excited phosphors based on an integrating sphere. The testing device comprises a fixed base, an integrating sphere, a light-emitting tube, a blue-light LED light source, a TEC temperature control fixture, a constant current source, a cosine collector, a spectrometer, a computer, a baffle, and a standard whiteboard. The device utilizes the advantages of adjustable LED spectral parameters and stable luminescence as an excitation light source, and the closed nature of the integrating sphere device allows for complete collection of light reflected by the phosphors. This method primarily tests phosphors and does not test multi-junction solar cells with complex structures, wide spectra, and multiple luminescence peaks. Summary of the Invention

[0005] The present invention addresses the shortcomings of the prior art in that it is unable to specifically quantify the lattice growth quality of each epitaxial layer of the sub-cell lattice within a multi-junction solar cell and to quantitatively evaluate the lattice quality globally, and that some prior art requires the destruction of the chip for quantitative defect characterization. The present invention provides a new detection device and diagnosis method for the lattice quality of the sub-cell within a multi-junction solar cell, which can comprehensively evaluate the lattice growth quality and the global lattice quality without damaging the chip to be tested.

[0006] The primary purpose of the present invention is to solve the above technical problems, and the technical solutions of the present invention are as follows:

[0007] A device for detecting the lattice quality of sub-cells in multi-junction solar cells, including: a copper probe station module, an optical integrating sphere, a high-precision spectrometer, an optical fiber, a power meter, and a processor;

[0008] One side of the optical integrating sphere has a circular opening, the copper probe station module is arranged at the circular opening of the optical integrating sphere, and the power meter is connected to the copper probe station module; the output end of the optical integrating sphere is connected to one end of the optical fiber, and the other end of the optical fiber is connected to a high-precision spectrometer; the signal output end of the high-precision spectrometer is connected to the signal input end of the processor, and the signal input end of the power meter is connected to the signal output end of the processor.

[0009] Furthermore, the copper probe station module comprises: an insulating holder, a base, and an electrical injection probe;

[0010] The insulating fixture is arranged on the base, and the electric injection probe is arranged on the insulating fixture; one end of the electric injection probe is connected to the negative pole of the power meter, and the other end is suspended in the air; the base is connected to the positive pole of the power meter; the base is arranged at the circular opening of the optical integrating sphere and the insulating fixture and the electric injection probe are both located inside the optical integrating sphere.

[0011] Diagnostic methods for the lattice quality of subcells within multi-junction solar cells include:

[0012] S1: placing a multi-junction solar cell to be tested on a base, with the positive electrode of the multi-junction solar cell to be tested contacting the base, and the negative electrode of the multi-junction solar cell to be tested contacting the other end of the electric injection probe;

[0013] S2: The positive electrode of the power meter injects a first forward current density into the internal sub-cell of the multi-junction solar cell to be tested through the base; the high-precision spectrometer reads the electroluminescence spectrum of the multi-junction solar cell under a first preset time through the optical fiber and sends it to the processor;

[0014] S3: After the first preset time, the current is turned off, and the high-precision spectrometer reads the background spectrum of the optical integrating sphere at the second preset time through the optical fiber and sends it to the processor;

[0015] S4: summing the first forward current density and the first preset current density to obtain the new first forward current density, and repeating steps S2 to S3 until the first forward current density is greater than the second preset current density;

[0016] S5: Obtain the measured spectrum of the standard light source and the background spectrum, calculate the absolute electroluminescence spectrum based on the electroluminescence spectrum of the multi-junction solar cell, and send it to the processor;

[0017] S6: The processor calculates a relationship between the internal luminous efficiency and the output current density of the sub-cell of the multi-junction solar cell to be tested based on the electroluminescence absolute spectrum and the first forward current density;

[0018] S7: deriving an internal luminous efficiency value under a preset working state according to a relationship between the internal luminous efficiency and the output current density of the sub-cell of the multi-junction solar cell to be tested and comparing it with a preset threshold value to determine the lattice quality of the sub-cell of the multi-junction solar cell to be tested.

[0019] Furthermore, in step S5, the formula for calculating the absolute electroluminescence spectrum is as follows:

[0020]

[0021] C standard (E) represents the standard spectrum of the standard light source, C gest (E) represents the measured spectrum of the standard light source, C bg (E) represents the background spectrum of the standard light source, f Rel.EL (E,J inj ) represents the electroluminescence spectra of all sub-cells measured at the first forward current density, f bg (E) represents the background spectrum when the sub-battery is not powered at the second preset time, J inj It represents the first forward current density, and E represents the photon energy corresponding to the luminous band of the sub-cell inside the multi-junction solar cell.

[0022] Furthermore, in step S6, the relationship between the internal luminous efficiency and the output current density of any sub-cell i in the N-junction solar cell in the light injection mode is as follows:

[0023]

[0024] i represents the sequence number of the subcells in the N-junction solar cell from top to bottom (1≤i≤N), η int i represents the internal luminous efficiency of any subcell i in a multi-junction solar cell, J ext represents the output current density of the multi-junction solar cell, It represents the weighted average value of the absorption coefficient of any subcell i in a multi-junction solar cell on the energy of the emitted photons, It represents the weighted average of the upper surface absorption rate of any subcell i in the multi-junction solar cell on the emitted photon energy, It represents the weighted average of the absorption rate of the lower surface of any subcell i in the multi-junction solar cell on the energy of the emitted photons, L i represents the thickness of the active region of any subcell inside a multi-junction solar cell, n i represents the material refractive index of any subcell i in a multi-junction solar cell, η ext i It represents the external luminous efficiency of any sub-cell i inside a multi-junction solar cell.

[0025] Furthermore, the calculation formula for the external luminous efficiency of the sub-cells in the multi-junction solar cell in the light injection mode is as follows:

[0026] η ext (J ext )=η ext [J total (J ext )| SC ]| LED

[0027] J ext represents the output current density of the multi-junction solar cell, η ext represents the external luminous efficiency of any subcells in multi-junction solar cells, J total It represents the total current density flowing through the sub-cells inside the multi-junction solar cell. SC means that the multi-junction solar cell is in light injection mode, and LED means that the multi-junction solar cell is in electrical injection mode.

[0028] Furthermore, the formula for the total current density of all sub-cells in the multi-junction solar cell in the light injection mode is as follows:

[0029]

[0030] i represents the sequence number of subcells in a multi-junction solar cell from top to bottom. represents the additional current density caused by the photoelectric coupling effect in any subcell i within the multi-junction solar cell, represents the photocurrent density generated by any subcell i in a multi-junction solar cell under illumination conditions, J ext represents the output current density of the multi-junction solar cell, It represents the total current density flowing through any sub-cell i inside the multi-junction solar cell.

[0031] Furthermore, the relationship between the external luminous efficiency and the total current density of the sub-cells in the multi-junction solar cell under the electric injection mode is as follows:

[0032]

[0033] J inj represents the first forward current density, J total represents the total current density flowing through the sub-cells of the multi-junction solar cell, LED represents that the multi-junction solar cell is in the electric injection mode, η ext The external luminous efficiency of sub-cells within a multi-junction solar cell.

[0034] Furthermore, the relationship between the external luminous efficiency of the sub-cells in the multi-junction solar cell and the first forward current density in the electric injection mode is as follows:

[0035]

[0036] f Abs.EL (E,J inj ) represents the absolute electroluminescence spectrum, E max The upper limit of the photon energy of the subcell in the multi-junction solar cell, E min represents the lower limit of the photon energy of the subcell inside the multi-junction solar cell, J inj represents the first forward current density, and q represents the unit charge.

[0037] Furthermore, the relationship between the total current density of all sub-cells in the multi-junction solar cell and the first forward current density in the electric injection mode is as follows:

[0038]

[0039] i represents the sequence number of subcells in a multi-junction solar cell from top to bottom. represents the total current density flowing through any subcell i in a multi-junction solar cell, represents the additional current density caused by the photoelectric coupling effect in any subcell i within the multi-junction solar cell, J inj It represents the first forward current density, and LED indicates that the multi-junction solar cell is in the electric injection mode.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] This method uses a multi-junction solar cell chip in electrical injection mode and, using a high-precision spectrometer and integrating sphere system, directly calculates the absolute electroluminescence spectrum and external luminous efficiency of each sub-cell as a function of injected current density, achieving high test accuracy. The method uses internal luminous efficiency as an evaluation metric for lattice quality to diagnose differences between the actual growth quality of all sub-cells and the ideal value, enabling comprehensive device process evaluation. This method allows for comprehensive assessment of both lattice growth quality and overall lattice quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a structural diagram of the device for detecting the lattice quality of sub-cells in a multi-junction solar cell provided in Example 1.

[0043] Figure 2 This is a structural diagram of the copper probe station module provided in Example 1.

[0044] Figure 3 A structural diagram of the calibration of the detection device for the lattice quality of sub-cells within a multi-junction solar cell provided in Example 1.

[0045] Figure 4 This is a numerical diagram of the internal luminous efficiency of three sub-cells of a conventional chip and a quantum well chip under the light injection mode provided in Example 1 at the maximum output power point, in the open circuit state, and in ideal materials.

[0046] Figure 5 Schematic diagram of a portion of the multi-junction solar cell structure provided in Example 1.

[0047] Figure 6 This is a line graph of the absolute electroluminescence spectrum of the sub-cells inside the quantum well multi-junction solar cell chip provided in Example 1.

[0048] Figure 7 This is a line graph of the external luminous efficiency and injection current density of the quantum well multi-junction solar cell chip sub-cell under the electric injection mode provided in Example 1.

[0049] Figure 8 This is a line graph showing the internal luminous efficiency and injection current density of a sub-cell of a quantum well multi-junction solar cell chip under the electrical injection mode provided in Example 1.

[0050] Figure 9 This is a line graph showing the relationship between the external luminous efficiency and output current density of the sub-cells of the quantum well multi-junction solar cell chip in the light injection mode provided in Example 1.

[0051] Figure 10This is a line graph showing the relationship between the internal luminous efficiency and output current density of a sub-cell of a quantum well multi-junction solar cell chip in the light injection mode provided in Example 1. DETAILED DESCRIPTION

[0052] The accompanying drawings are for illustrative purposes only and are not to be construed as limiting this patent;

[0053] In order to better illustrate this embodiment, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product size;

[0054] It is understandable to those skilled in the art that some well-known structures and descriptions thereof may be omitted in the drawings.

[0055] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0056] Example 1

[0057] like Figure 1 As shown, the device for detecting the lattice quality of sub-cells in a multi-junction solar cell includes: a copper probe station module, an optical integrating sphere 2, a high-precision spectrometer 4, an optical fiber 5, a power meter 6, and a processor 7;

[0058] One side of the optical integrating sphere 2 has a circular opening, the copper probe station module is arranged at the circular opening of the optical integrating sphere 2, and the power meter 6 is connected to the copper probe station module; the output end of the optical integrating sphere 2 is connected to one end of the optical fiber 5, and the other end of the optical fiber 5 is connected to the high-precision spectrometer 4.

[0059] It should be noted that the processor is usually a computer.

[0060] Furthermore, if Figure 2 As shown, the copper probe station module includes: an insulating holder 9, a base 3, and an electric injection probe 10;

[0061] The insulating fixture 9 is arranged on the base 3, and the electric injection probe 10 is arranged on the insulating fixture 9; one end of the electric injection probe 10 is connected to the negative pole of the power meter 6, and the other end is suspended; the base 3 is connected to the positive pole of the power meter 6; the base is arranged at the circular opening of the optical integrating sphere and the insulating fixture 9 and the electric injection probe 10 are both located inside the optical integrating sphere 2; the signal output end of the high-precision spectrometer 4 is connected to the signal input end of the processor 7, and the signal input end of the power meter 6 is connected to the signal output end of the processor 7.

[0062] It should be noted that the testing device also includes a vacuum pump 8 connected to the base 3. The base 3 is provided with air holes. During the test, the vacuum pump is used to ensure a tight fit between the chip back electrode and the base surface. The insulating fixture 9 includes an insulating gasket 11.

[0063] The copper probe station module can be placed inside the integrating sphere as the light source input end. The surface of the base is equipped with an air hole connected to the vacuum pump 8, which can tightly adsorb the lower surface electrode (positive electrode) of the multi-junction solar cell chip 1 on the surface of the base and obtain good electrical contact. The base is also equipped with an insulated wire extending to the outside of the integrating sphere; an electric injection probe 10 is provided above the base and connected to the upper surface electrode (negative electrode) of the sub-cell chip inside the multi-junction solar cell. The tail of the probe is equipped with an insulated wire extending to the outside of the integrating sphere. The base and the electric injection probe are fixed with an insulating fixture 9 to achieve electrical insulation of the positive and negative electrodes of the chip.

[0064] The optical integrating sphere 2 has a high reflective coating inside, which is used to uniformly diffuse the light intensity of the chip's electroluminescent signal at all angles.

[0065] It should be noted that the cells tested in the following content are two different InGaP / GaAs / InGaAs triple-junction solar cell chips (abbreviated as: IMM-3JSC) as examples, divided into traditional type and quantum well type.

[0066] High-precision spectrometer 4 is used to detect the electroluminescence (EL) spectral signals of the top, middle, and bottom subcells (i=1, 2, 3) within a triple-junction solar cell. The wavelength detection range covers the 400nm-1400nm spectral range of the EL of the three subcells. It includes a high-precision UV-visible spectrometer for measuring the EL signals of the top and middle cells (400nm-1000nm) and a high-precision near-infrared spectrometer for measuring the EL signal of the bottom cell (1000nm-1400nm).

[0067] The input end of the optical fiber 5 is connected to the output end of the optical integrating sphere 2, and the other end is connected to the light input port of the high-precision spectrometer 4, which is used to read the chip electroluminescence signal after full-angle diffuse reflection homogenization.

[0068] The positive and negative output ends of the current source 6 are respectively connected to the positive wire of the base 3 and the negative wire at the tail of the electric injection probe 10, thereby achieving electrical communication with the positive and negative electrodes of the triple-junction solar cell chip 1, and are used to provide it with injection currents of different sizes during electroluminescence spectrum measurement.

[0069] The high-precision spectrometer 4 and the current source 6 are both connected to a computer 7. The computer is used to control the current output of the DC current source, the exposure time of the high-precision spectrometer to measure the electroluminescence spectrum signal, and the central wavelength of the spectrum signal.

[0070] It should be noted that if Figure 3 As shown, the test device further includes a standard light source 12. The light intensity of the standard light source 12 is known and is used to calibrate the relative intensity of the electroluminescence spectra of the three sub-cells of the multi-junction solar cell chip 1.

[0071] It should be noted that the present invention proposes an effective, non-destructive, high-precision detection device and diagnostic method that can realize the lattice quality of sub-cells in any multi-junction solar cell chip. The main principle is to set the multi-junction solar cell chip in the electric injection mode (LED mode, no light mode), and directly calculate the absolute electroluminescence spectrum f of each sub-cell through a high-precision spectrometer and integrating sphere system. Abs.EL and external luminous efficiency and the injected current density J inj All data are calibrated with standard light source, so the test accuracy is high. Combined with the material and structural parameters of the sub-cell, the internal luminous efficiency of all sub-cells was calculated. and the injected current density J inj The calculation takes into account the influence of the photoelectric coupling effect between sub-cells, and the internal luminous efficiency under the light injection mode (solar cell mode, light mode) can also be derived. With the output current density J ext The internal luminous efficiency As an evaluation indicator of lattice quality, it can diagnose the difference between the actual growth quality of all sub-cells and the ideal value, thus achieving process evaluation of the entire device. This method is also applicable to the evaluation of lattice quality and process parameters of single-junction and multi-junction photovoltaic cells made of other non-III-V materials, and has universal applicability.

[0072] Diagnostic methods for the lattice quality of subcells within multi-junction solar cells include:

[0073] S1: placing a multi-junction solar cell to be tested on a base, with the positive electrode of the multi-junction solar cell to be tested contacting the base, and the negative electrode of the multi-junction solar cell to be tested contacting the other end of the electric injection probe;

[0074] S2: The positive electrode of the power meter injects a first forward current density into the internal sub-cell of the multi-junction solar cell to be tested through the base; the high-precision spectrometer reads the electroluminescence spectrum of the multi-junction solar cell under a first preset time through the optical fiber and sends it to the processor;

[0075] S3: After the first preset time, the current is turned off, and the high-precision spectrometer reads the background spectrum of the optical integrating sphere at the second preset time through the optical fiber and sends it to the processor;

[0076] S4: summing the first forward current density and the first preset current density to obtain the new first forward current density, and repeating steps S2 to S3 until the first forward current density is greater than the second preset current density;

[0077] S5: Obtain the measured spectrum of the standard light source and the background spectrum, calculate the absolute electroluminescence spectrum based on the electroluminescence spectrum of the multi-junction solar cell, and send it to the processor;

[0078] S6: The processor calculates a relationship between the internal luminous efficiency and the output current density of the sub-cell of the multi-junction solar cell to be tested based on the electroluminescence absolute spectrum and the first forward current density;

[0079] S7: deriving an internal luminous efficiency value under a preset working state according to a relationship between the internal luminous efficiency and the output current density of the sub-cell of the multi-junction solar cell to be tested and comparing it with a preset threshold value to determine the lattice quality of the sub-cell of the multi-junction solar cell to be tested.

[0080] It should be noted that, in the whole process, the injection current density value J is gradually increased. inj When injecting a small current, the sampling current interval should be as small as possible, such as 0.01mA / cm 2 As the injection current increases, the sampling current interval also increases gradually, such as 0.1mA / cm 2 , 1mA / cm 2 Until the maximum value of the measured current is reached (at least 1.5 times higher than the short-circuit current density), the full electric injection level (1.5J SC ≥J inj ≥0.01mA / cm 2 ) sub-cell's electroluminescence spectrum. As the injected current increases, the sub-cell's electroluminescence intensity increases. Therefore, the exposure time needs to be appropriately shortened to maintain a reasonable intensity distribution. Spectra were collected for these two sets of different exposure times at the same injected current density with varying exposure times. If shortening the exposure time fails to meet the required time accuracy, a neutral density filter is placed against the surface of the fiber input end to reduce the luminescence intensity.

[0081] In a specific embodiment, Figure 4 As shown, the three sub-batteries inside the two IMM-3JSC chips under light injection mode are at the maximum output power point (J ext =J MMP ) and open circuit state (J ext =0) by the three sub-batteries obtained by the test method and device of test data. The closer the value of is to the ideal value of 1, the better the lattice quality and the fewer lattice defects the sub-cell has. Therefore, the above results can be used to compare the lattice quality of samples with the same structure and different process conditions, and can also be used to compare the lattice quality of samples with the same structure but different batches, providing a scientific reference for device structure optimization and process improvement. For example, Figure 4 As shown: First, the lattice quality comparison of the three sub-cells within the two triple-junction solar cell chips can be determined. That is, the middle cell (GaAs) has the best lattice quality, the top cell (InGaP) is second, and the bottom cell (InGaAs) is the worst. Secondly, the difference in lattice quality between the quantum well type and the traditional IMM-3JSC chip can be compared horizontally. That is, the internal luminous efficiency is significantly improved after the quantum well is introduced into the GaAs middle cell ( From 0.291 to 0.877); In addition, the bottom cell of the quantum well type sample has a higher lattice mismatch due to the introduction of a higher In component and therefore has a lower lattice quality ( Finally, it is also possible to conduct a horizontal comparison of electrical properties between samples with different structural designs, providing more accurate guidance for subsequent chip design and development.

[0082] Combine Figure 1 、 Figure 3 The steps for a single test are as follows. The entire test process is recommended to be performed in a dark environment:

[0083] S101: Connect a copper probe station module, place a multi-junction solar cell to be tested on a base, with the positive electrode of the multi-junction solar cell to be tested contacting the base, and the negative electrode of the multi-junction solar cell to be tested contacting the other end of the electric injection probe;

[0084] S102: The positive electrode of the power meter injects a certain forward current density J into the internal sub-cell of the multi-junction solar cell to be tested through the base. inj , the optical integrating sphere is fixed on the base to achieve optical sealing;

[0085] S103: Connect one end of the optical fiber to the output end of the optical integrating sphere, and the other end of the optical fiber to the light input port of the high-precision UV-visible spectrometer.

[0086] S104: Use a computer to control the power meter to inject a forward current density J into the multi-junction solar cell to be tested inj ; Using a computer to adjust the corresponding exposure time; reading the electroluminescence spectrum signal of a single or multiple sub-cells that can be measured under the corresponding exposure time through an optical fiber, and sending it to the computer;

[0087] S105: Turning off the current, the ultraviolet-visible high-precision spectrometer reads the background spectrum under the same exposure time through the optical fiber and sends it to the computer;

[0088] S106: Gradually increase the injection current density value J inj Repeat S4 to S5 until the maximum value of the measured current is reached (at least 1.5 times higher than the short-circuit current density), and obtain the maximum value of the measured current under all electrical injection levels (1.5J SC ≥J inj ≥0.01mA / cm 2 ) electroluminescence spectrum of the subcell;

[0089] It should be noted that, in the whole process, the injection current density value J is gradually increased. inj When injecting a small current, the sampling current interval should be as small as possible, such as 0.01mA / cm 2 As the injection current increases, the sampling current interval also increases gradually, such as 0.1mA / cm 2 , 1mA / cm 2 As the injected current density increases, the subcell's electroluminescence intensity increases. Therefore, the exposure time needs to be shortened appropriately to maintain a reasonable intensity distribution. Spectra were collected for two different exposure times at the same injected current density with varying exposure times. If shortening the exposure time fails to meet the required time accuracy, a neutral density filter is placed against the fiber input end to reduce the luminescence intensity.

[0090] S107: Keep one end of the optical fiber connected to the output end of the optical integrating sphere, and connect the other end of the optical fiber to the input end of the high-precision near-infrared spectrometer, measure the electroluminescence spectrum signal of the measurable single or multiple sub-cells, send it to the computer, and repeat S104 to S106;

[0091] It should be noted that in order to eliminate interference from visible light band signals, the long-wave pass filter needs to be accurately placed and close to the surface of the optical fiber input end during the entire test process to filter out visible light band signals.

[0092] S108: Disassemble the copper probe station module, preheat the standard light source for 15 minutes, place it in the integrating sphere, turn it on, obtain the measured spectrum of the standard light source, and send it to the computer. Turn off the standard light source to obtain the background spectrum and send it to the computer;

[0093] It should be noted that in order to obtain the subsequent internal luminous efficacy value, it is also necessary to use a spectrophotometer to measure the reflectivity R of the upper and lower surfaces of the battery chip. f 、R b And measure its EQE using a monochromator and a lock-in amplifier.

[0094] S109: Calculating the absolute electroluminescence spectrum, calculating the relationship between the external luminous efficiency and the injected current density based on the absolute electroluminescence spectrum, and further calculating the relationship between the internal luminous efficiency and the output current density of the sub-cell inside the multi-junction solar cell to be tested;

[0095] S110: deriving an internal luminous efficiency value under a corresponding working state according to a relationship between the internal luminous efficiency and the output current density of the sub-cell of the multi-junction solar cell to be tested and comparing it with an ideal value to determine the lattice quality of the sub-cell of the multi-junction solar cell to be tested.

[0096] Furthermore, in step S5, the formula for calculating the absolute electroluminescence spectrum is as follows:

[0097]

[0098] C standard (E) represents the standard spectrum of the standard light source, C test (E) represents the measured spectrum of the standard light source, C bg (E) represents the background spectrum of the standard light source, f Rel.EL (E,J inj ) represents the electroluminescence spectra of all sub-cells measured at the first forward current density (exposure time is 1 s), f bg (E) represents the background spectrum of the sub-cell when it is not powered at the second preset time (exposure time is 1s), J inj represents the first forward current density, and E represents the photon energy of the sub-cell corresponding to the internal luminescence band of the multi-junction solar cell.

[0099] Furthermore, in step S6, the relationship between the internal luminous efficiency and the output current density of any sub-cell i in the N-junction solar cell in the light injection mode is as follows:

[0100]

[0101] i represents the sequence number of the subcells in the N-junction solar cell from top to bottom (1≤i≤N), η int i represents the internal luminous efficiency of any subcell i in a multi-junction solar cell, J ext represents the output current density of the multi-junction solar cell, It represents the weighted average value of the absorption coefficient of any subcell i in a multi-junction solar cell on the energy of the emitted photons, It represents the weighted average of the upper surface absorption rate of any subcell i in the multi-junction solar cell on the emitted photon energy, represents the lower surface absorption rate of any subcell i in a multi-junction solar cell, L i represents the thickness of the active region of any subcell i in a multi-junction solar cell, ni represents the material refractive index of any subcell i in a multi-junction solar cell, η ext i It represents the external luminous efficiency of any sub-cell i inside a multi-junction solar cell.

[0102] It should be noted that if Figure 5 As shown, a multi-junction solar cell contains multiple sub-cells and other more sophisticated multi-layer heterojunction structures. This method only calculates the lattice quality information of each sub-cell, where i represents the sub-cell number arranged from top to bottom within the multi-junction solar cell.

[0103] Furthermore, the calculation formula for the external luminous efficiency of the sub-cells in the multi-junction solar cell in the light injection mode is as follows:

[0104] η ext (J ext )=η ext [J total (J ext )| SC ]| LED

[0105] J ext represents the output current density of the multi-junction solar cell, η ext represents the external luminous efficiency of any subcells in multi-junction solar cells, J total It represents the total current density flowing through the sub-cells inside the multi-junction solar cell. SC means that the multi-junction solar cell is in light injection mode, and LED means that the multi-junction solar cell is in electrical injection mode.

[0106] Furthermore, considering the photoelectric coupling effect between sub-cells, the formula for the total current density of all sub-cells in the multi-junction solar cell in the light injection mode is as follows:

[0107]

[0108] i represents the sequence number of subcells in a multi-junction solar cell from top to bottom. represents the additional current density caused by the photoelectric coupling effect in any subcell i within the multi-junction solar cell, represents the photocurrent density generated by any subcell i in a multi-junction solar cell under illumination conditions, J ext represents the output current density of the multi-junction solar cell, It represents the total current density flowing through any sub-cell i inside the multi-junction solar cell.

[0109] Furthermore, the relationship between the external luminous efficiency and the total current density of the sub-cells in the multi-junction solar cell under the electric injection mode is as follows:

[0110]

[0111] J inj represents the first forward current density, J total represents the total current density flowing through the sub-cells of the multi-junction solar cell, LED represents that the multi-junction solar cell is in the electric injection mode, η ext The external luminous efficiency of sub-cells within a multi-junction solar cell.

[0112] Furthermore, the relationship between the external luminous efficiency of the sub-cells in the multi-junction solar cell and the first forward current density in the electric injection mode is as follows:

[0113]

[0114] f Abs.EL (E,J inj ) represents the absolute electroluminescence spectrum, E max The upper limit of the photon energy of the subcell in the multi-junction solar cell, E min represents the lower limit of the photon energy of the subcell inside the multi-junction solar cell, J inj represents the first forward current density, and q represents the unit charge.

[0115] Furthermore, the relationship between the total current density of all sub-cells in the multi-junction solar cell and the first forward current density in the electric injection mode is as follows:

[0116]

[0117] i represents the sequence number of subcells in a multi-junction solar cell from top to bottom. represents the total current density flowing through any subcell i in a multi-junction solar cell, represents the additional current density caused by the photoelectric coupling effect in any subcell i within the multi-junction solar cell, J inj Represents the first forward current density, and the LED indicates that the solar cell is in the electric injection mode.

[0118] In the electrical injection mode, the relationship between the additional current density caused by the photoelectric coupling effect and the total current in the anyon cell (i-1) is:

[0119]

[0120] It should be noted that this patent takes into account the influence of the photoelectric coupling effect between sub-cells in the calculations under both the light injection mode and the electrical injection mode, and ultimately derives the functional relationship between the internal luminous efficiency and the output current density under the light injection mode, with extremely high calculation accuracy.

[0121] The calculation formula for the weighted average of the absorption coefficient of any sub-cell i within a multi-junction solar cell on the photon energy emitted by the sub-cell is as follows:

[0122]

[0123] The calculation formula for the weighted average of the upper surface absorptivity of any sub-cell i within a multi-junction solar cell over the photon energy emitted by the sub-cell is as follows:

[0124]

[0125] The calculation formula for the weighted average of the absorption rate of the lower surface of any sub-cell i in a multi-junction solar cell over the energy of the photons emitted by the sub-cell is as follows:

[0126]

[0127] in:

[0128]

[0129] Ω c and are the interface emission critical angle and the average photon energy of electroluminescence of any subcell i, respectively.

[0130] The ratio of the light extraction rate of the lower surface of anyon cell i in the stack to the light extraction rate emitted into the air through the upper surface of the device is as follows:

[0131]

[0132] The formula for the photocurrent density generated by any subcell i in a multi-junction solar cell under illumination conditions is as follows:

[0133]

[0134] S(E) represents the energy distribution density function of the number of photons corresponding to the light source. represents the upper limit of the photon energy emitted by any subcell i in a multi-junction solar cell, The lower limit of the photon energy emitted by any subcell i in a multi-junction solar cell, E represents the photon energy, EQE i represents the external quantum efficiency of anyon cell i inside a multi-junction solar cell.

[0135] The absolute electroluminescence spectra of the three sub-cells inside the quantum well type IMM-3JSC chip are as follows: Figure 6 As shown; the external luminous efficiency of the three sub-cells of the quantum well type IMM-3JSC chip under the electric injection mode (LED mode, no light mode) and the injected current density J inj The relationship as Figure 7As shown; the internal luminous efficiency of the three sub-cells of the quantum well type IMM-3JSC chip under the electric injection mode (LED mode, no light mode) and the injected current density J inj The relationship as Figure 8 As shown; the external luminous efficiency of the three sub-cells of the quantum well type IMM-3JSC chip under the light injection mode (solar cell mode, light mode) and output current density J ext The relationship as Figure 9 As shown; the internal luminous efficiency of the three sub-cells of the quantum well type IMM-3JSC chip under the light injection mode (solar cell mode, light mode) and output current density J ext The relationship as Figure 10 shown.

[0136] The same or similar reference numerals correspond to the same or similar components;

[0137] The terms used in the drawings to describe positional relationships are for illustrative purposes only and should not be construed as limiting this patent;

[0138] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A device for detecting the lattice quality of subcells in a multi-junction solar cell, characterized in that: include: Copper probe station module, optical integrating sphere (2), high-precision spectrometer (4), optical fiber (5), power meter (6), processor (7); One side of the optical integrating sphere (2) has a circular opening, the copper probe station module is arranged at the circular opening of the optical integrating sphere (2), and the power meter (6) is connected to the copper probe station module; the output end of the optical integrating sphere (2) is connected to one end of an optical fiber (5), and the other end of the optical fiber (5) is connected to a high-precision spectrometer (4); the signal output end of the high-precision spectrometer (4) is connected to the signal input end of the processor (7), and the signal input end of the power meter (6) is connected to the signal output end of the processor (7).

2. The device for detecting the lattice quality of sub-cells in a multi-junction solar cell according to claim 1, characterized in that: The copper probe station module comprises: an insulating holder (9), a base (3), and an electric injection probe (10); The insulating holder (9) is arranged on the base (3), and the electric injection probe (10) is arranged on the insulating holder (9); one end of the electric injection probe (10) is connected to the negative pole of the power meter (6), and the other end is suspended; the base (3) is connected to the positive pole of the power meter (6); the base (3) is arranged at the circular opening of the optical integrating sphere (2), and the insulating holder (9) and the electric injection probe (10) are both located inside the optical integrating sphere (2).

3. A method for diagnosing the lattice quality of subcells in a multi-junction solar cell, applied to the detection device of claim 1 or 2, characterized in that: include: S1: placing a multi-junction solar cell to be tested on a base, with the positive electrode of the multi-junction solar cell to be tested contacting the base, and the negative electrode of the multi-junction solar cell to be tested contacting the other end of the electric injection probe; S2: The positive electrode of the power meter injects a first forward current density into the internal sub-cell of the multi-junction solar cell to be tested through the base; the high-precision spectrometer reads the electroluminescence spectrum of the multi-junction solar cell under a first preset time through the optical fiber and sends it to the processor; S3: After the first preset time, the current is turned off, and the high-precision spectrometer reads the background spectrum of the optical integrating sphere at the second preset time through the optical fiber and sends it to the processor; S4: summing the first forward current density and the first preset current density to obtain the new first forward current density, and repeating steps S2 to S3 until the first forward current density is greater than the second preset current density; S5: Obtain the measured spectrum of the standard light source and the background spectrum, calculate the absolute electroluminescence spectrum based on the electroluminescence spectrum of the multi-junction solar cell, and send it to the processor; S6: The processor calculates a relationship between the internal luminous efficiency and the output current density of the sub-cell of the multi-junction solar cell to be tested based on the electroluminescence absolute spectrum and the first forward current density; S7: deriving an internal luminous efficiency value under a preset working state according to a relationship between the internal luminous efficiency and the output current density of the sub-cell of the multi-junction solar cell to be tested and comparing it with a preset threshold value to determine the lattice quality of the sub-cell of the multi-junction solar cell to be tested.

4. The method for diagnosing the lattice quality of subcells in a multi-junction solar cell according to claim 3, characterized in that: In step S5, the formula for calculating the absolute electroluminescence spectrum is as follows: c standard (E) represents the standard spectrum of the standard light source, C test (E) represents the measured spectrum of the standard light source, C bg (E) represents the background spectrum of the standard light source, f Rel.EL (E,J inj ) represents the electroluminescence spectra of all sub-cells measured at the first forward current density, f bg (E) represents the background spectrum when the sub-battery is not powered at the second preset time, J inj It represents the first forward current density, and E represents the photon energy corresponding to the luminous band of the sub-cell inside the multi-junction solar cell.

5. The method for diagnosing the lattice quality of subcells in a multi-junction solar cell according to claim 3, characterized in that: In step S6, the relationship between the internal luminous efficiency and the output current density of any sub-cell i in the N-junction solar cell in the light injection mode is as follows: i represents the sequence number of the subcells in the N-junction solar cell from top to bottom (1≤i≤N), η int i represents the internal luminous efficiency of any subcell i in a multi-junction solar cell, J ext represents the output current density of the multi-junction solar cell, It represents the weighted average value of the absorption coefficient of any subcell i in a multi-junction solar cell on the energy of the emitted photons, It represents the weighted average of the upper surface absorption rate of any subcell i in the multi-junction solar cell on the emitted photon energy, It represents the weighted average of the absorption rate of the lower surface of any subcell i in the multi-junction solar cell on the energy of the emitted photons, L i represents the thickness of the active region of any subcell i in a multi-junction solar cell, n i represents the material refractive index of any subcell i in a multi-junction solar cell, η ext i It represents the external luminous efficiency of any sub-cell i inside a multi-junction solar cell.

6. The method for diagnosing the lattice quality of subcells in a multi-junction solar cell according to claim 5, characterized in that: The calculation formula for the external luminous efficiency of the sub-cells in the multi-junction solar cell under the light injection mode is as follows: or ext (J ext )=η ext [J total (J ext )| SC ]| LED J ext represents the output current density of the multi-junction solar cell, η ext represents the external luminous efficiency of any subcells in multi-junction solar cells, J total It represents the total current density flowing through the sub-cells inside the multi-junction solar cell. SC means that the multi-junction solar cell is in light injection mode, and LED means that the multi-junction solar cell is in electrical injection mode.

7. The method for diagnosing the lattice quality of subcells in a multi-junction solar cell according to claim 6, characterized in that: The formula for the total current density of all sub-cells in the multi-junction solar cell under the light injection mode is as follows: i represents the sequence number of subcells in a multi-junction solar cell from top to bottom. represents the additional current density caused by the photoelectric coupling effect in any subcell i within the multi-junction solar cell, represents the photocurrent density generated by any subcell i in a multi-junction solar cell under illumination conditions, J ext represents the output current density of the multi-junction solar cell, It represents the total current density flowing through any sub-cell i inside the multi-junction solar cell.

8. The method for diagnosing the lattice quality of subcells in a multi-junction solar cell according to claim 6, characterized in that: The relationship between the external luminous efficiency and total current density of the sub-cells in a multi-junction solar cell under the electric injection mode is as follows: J inj represents the first forward current density, J total represents the total current density flowing through the sub-cells of the multi-junction solar cell, LED represents that the multi-junction solar cell is in the electric injection mode, η ext The external luminous efficiency of sub-cells within a multi-junction solar cell.

9. The method for diagnosing the lattice quality of subcells in a multi-junction solar cell according to claim 8, characterized in that: The relationship between the external luminous efficiency of the sub-cells in a multi-junction solar cell and the first forward current density in the electrical injection mode is as follows: f Abs.EL (E,J inj ) represents the absolute electroluminescence spectrum, E max The upper limit of the photon energy of the subcell in the multi-junction solar cell, E min represents the lower limit of the photon energy of the subcell inside the multi-junction solar cell, J inj represents the first forward current density, and q represents the unit charge.

10. The method for diagnosing the lattice quality of subcells in a multi-junction solar cell according to claim 8, characterized in that: The relationship between the total current density of all sub-cells in a multi-junction solar cell and the first forward current density in the electric injection mode is as follows: i represents the sequence number of subcells in a multi-junction solar cell from top to bottom. represents the total current density flowing through any subcell i in a multi-junction solar cell, represents the additional current density caused by the photoelectric coupling effect in any subcell i within the multi-junction solar cell, J inj It represents the first forward current density, and LED indicates that the multi-junction solar cell is in the electric injection mode.

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