Wide-spectrum photoelectric conversion device quantum efficiency test system and method

Abstract

The invention discloses a wide-spectrum photoelectric conversion device quantum efficiency test system and method. The system comprises a quantum efficiency test box, a power box, a laser power meter, a Keithley source meter, a control drive circuit single-chip microcomputer, a computer and the like. According to the test system, the external quantum efficiency (EQE), the internal quantum efficiency (IQE) and the surface reflectivity R of the device to be tested can be measured at the same time, a standard device does not need to be used for calibration before test, the testable spectral band range is wide and ranges from 300 nm to 2250 nm, and the quantum efficiency measurement requirements of various different forbidden band photovoltaic cells or photoelectric conversion devices are met.

Description

Technical Field

[0001] The invention relates to a quantum efficiency testing system for a photoelectric conversion device, and in particular to a quantum efficiency testing system and method for a wide-band photoelectric conversion device. Background Art

[0002] Quantum efficiency testing involves complex optoelectronic physics principles and has high requirements for related technologies. At present, the degree of independent research and development of optoelectronic device quantum efficiency testing equipment in China is low. The testing equipment used by various institutions is mainly imported from abroad and is very expensive. Moreover, most testing equipment can only provide EQE test results. For IQE results, users need to use a reflectivity tester to obtain sample reflectivity data, and then calculate it with the EQE measurement value. The measurement steps and data processing links need to be borne by the user, and the operation is relatively cumbersome. In addition, in order to ensure the accuracy of the test results, conventional quantum efficiency test systems need to use standard semiconductor devices such as Si detectors, Ge detectors or InGaAs detectors to perform numerical calibration of the corresponding bands before testing. This results in a smaller spectral band range for conventional quantum efficiency test equipment, which cannot meet the measurement needs of various types of different bandgap photovoltaic cells. When testing wide-band batteries that can absorb infrared light, the general method is to use Si detectors for testing in the band range less than 1100nm, and use Ge or InGaAs detectors for testing in the band range greater than 1100nm, and splice the two external quantum efficiency curves measured above. The spliced ​​external quantum efficiency curves often have differences at the junction, resulting in low reliability of the test results and failure to accurately reflect the quantum efficiency characteristics of the optoelectronic device to be tested. In addition, after a certain period of use, the physical properties of the semiconductor material of this type of quantum efficiency tester that uses semiconductor devices as core measurement elements will gradually degrade, and the device performance will decline or even fail, resulting in reduced instrument measurement accuracy and a significant shortening of the equipment's service life. Summary of the invention

[0003] Purpose of the invention: In view of the above problems, the present invention proposes a wide-band photoelectric conversion device quantum efficiency testing system and method, which broadens the one-time measurement spectral range of the quantum efficiency test. The EQE, IQE and R values ​​can be directly generated by the system without the need for the user to perform additional calculations, and there is no need to use a benchmark reference photoelectric conversion device in the test.

[0004] Technical solution: The technical solution adopted by the present invention is a quantum efficiency test system for a wide-spectrum photoelectric conversion device. The main body of the test system includes a test box and a computer for collecting and processing data; the test box includes a box body, an external quantum efficiency test unit and a reflectivity test unit; the box body is used to provide a closed and light-proof test environment; the external quantum efficiency test unit includes a first test light source, a laser power meter and a digital source meter, the laser power meter is used to measure the laser power of the first test light source, and the digital source meter is used to measure the short-circuit current of the sample in the external quantum efficiency test unit; the reflectivity test unit includes a second test light source, a scanning galvanometer, an integrating sphere and a control drive circuit single-chip microcomputer, the integrating sphere is provided with a light detector, the output signal of the light detector is sent to the control drive circuit single-chip microcomputer to obtain the output voltage of the light detector; the first and second test light sources both use a multi-wavelength laser combiner.

[0005] The test system does not need to be calibrated using a standard semiconductor device before testing.

[0006] The computer calculates the external quantum efficiency and internal quantum efficiency of the sample based on the collected laser power of lasers of different wavelengths, the short-circuit current of the sample under irradiation with lasers of different wavelengths, and the output voltage of the photodetector before and after the lasers of different wavelengths are reflected by the sample at the integrating sphere.

[0007] The external quantum efficiency processing of the sample includes: the computer calculates the external quantum efficiency of the sample based on the laser power of lasers of different wavelengths collected and the short-circuit current of the sample under the irradiation of lasers of different wavelengths. The calculation formula is:

[0008]

[0009] In the formula, EQE λ is the external quantum efficiency of the sample under different wavelength laser irradiation; k λ is a constant term, k λ =πd 2 hc / 4eλ, where d is the aperture of the laser power meter detector, e is the electron charge, h is Planck's constant, c is the speed of light in vacuum, and λ is the wavelength; is the short-circuit current of the sample under laser irradiation of different wavelengths; P i It is the power value of laser lamp beads with different wavelengths of laser.

[0010] The internal quantum efficiency processing of the sample includes: the computer calculates the internal quantum efficiency of the sample based on the laser power of different wavelengths of lasers collected, the short-circuit current of the sample under the irradiation of lasers of different wavelengths, and the output voltage of the sample before and after the lasers of different wavelengths are reflected by the sample at the integrating sphere. The calculation formula is:

[0011]

[0012] In the formula, IQE λ is the internal quantum efficiency of the sample under different wavelength laser irradiation; U *i U is the static DC output voltage when the laser beam is directly incident on the integrating sphere, that is, the output voltage of the photodetector when there is no sample involved in the reflection of lasers of different wavelengths at the integrating sphere; i is the output voltage corresponding to the laser of different wavelengths after being reflected by the sample.

[0013] The computer also calculates the reflectivity of the sample, including: the computer calculates the reflectivity of the sample based on the output voltage of the sample before and after the lasers of different wavelengths are reflected by the sample at the integrating sphere, and the calculation formula is:

[0014]

[0015] In the formula, R λ is the reflectivity of the sample under different wavelengths of laser irradiation, U *i U is the static DC output voltage when the laser beam is directly incident on the integrating sphere, that is, the output voltage of the photodetector when there is no sample involved in the reflection of lasers of different wavelengths at the integrating sphere; i is the output voltage corresponding to the laser of different wavelengths after being reflected by the sample.

[0016] The digital source meter automatically scans and measures to obtain the IV curve of the sample, and sends the data to the computer. The computer processes the IV curve data to obtain the short-circuit current of the sample under the irradiation of lasers of different wavelengths. The computer controls the control drive circuit single-chip microcomputer through program control, so that the galvanometer drive circuit in the single-chip microcomputer controls the rotation of the scanning galvanometer in the reflectivity test unit. The control drive circuit single-chip microcomputer integrates the scanning galvanometer driver, operational amplifier, and phase-locked amplifier into a single chip, converts the photocurrent signal generated by the light detector when it is illuminated into a voltage signal through the amplifier circuit, and amplifies and phase-locks the test signal with the same frequency and phase as the reference signal.

[0017] The integrating sphere is provided with a plurality of openings; the scanning galvanometer rotates periodically at a certain frequency, and the incident laser is reflected by the scanning galvanometer to form light rays of different directions, which are incident on the inner wall of the integrating sphere and the sample through the openings; the multi-wavelength laser combiner includes a plurality of laser lamp beads for providing near-infrared light in the wavelength range of 300nm to 2250nm; the test system also includes a power supply box for providing power to the system.

[0018] The present invention also provides a method for testing the quantum efficiency of a wide-band photoelectric conversion device, comprising the following steps:

[0019] (1) The test system is not calibrated using standard semiconductor devices before testing;

[0020] (2) The laser power of each monochromatic laser lamp bead in the multi-wavelength laser combiner of the external quantum efficiency test unit is measured in sequence by a laser power meter, and the short-circuit current of the sample under the irradiation of lasers of different wavelengths in the range of 300nm to 2250nm is measured in sequence by a Keithley source meter;

[0021] (3) Debugging the scanning galvanometer; measuring the output voltage of the photodetector before and after the laser of different wavelengths at the integrating sphere is reflected by the sample in the range of 300nm to 2250nm by controlling the single chip microcomputer of the driving circuit;

[0022] (4) Through computer processing, the external quantum efficiency value EQE, internal quantum efficiency value IQE and reflectivity value R of the sample in the spectral range of 300nm to 2250nm are obtained.

[0023] The method also includes: (5) using a computer to fit the results of the external quantum efficiency value EQE, the internal quantum efficiency value IQE and the reflectivity value R, and drawing a curve graph of the EQE, IQE and R of the sample.

[0024] Beneficial effects: Compared with traditional quantum efficiency test equipment, the present invention has the following advantages: (1) It uses laser lamp beads instead of monochromators as the light source of the test system, which enhances the incident light intensity on the surface of the device to be tested, can meet the test requirements of high-intensity, high-current response devices such as TPV batteries, and improves the test reliability; (2) Compared with the quantum efficiency tester with traditional wide-spectrum light sources (such as xenon lamps) and monochromators, it eliminates the need for complex optical path design and the use of expensive components such as monochromators, avoids energy loss, reduces system complexity, and effectively controls production costs; (3) The laser beam has a small divergence angle and good collimation, and can accurately control the size and position of the spot to avoid measurement errors caused by non-uniform irradiation, which is suitable for micro-area QE testing, such as local defect analysis of photovoltaic cells; (4) There is no need to use a reference reference photoelectric conversion device during the test, which is fundamentally The problem of semiconductor device degradation affecting the measurement accuracy of the equipment is avoided; (5) When testing the quantum efficiency of a wide-band photoelectric conversion device, there is no need to splice the quantum efficiency curves measured by two detectors with different response bands (such as Si and Ge detectors), the curve is complete and smooth, and the equipment has high measurement accuracy; (6) The internal and external quantum efficiencies and surface reflectivity of the device can be measured simultaneously, without the need for users to perform additional manual calculations, which is convenient and fast; (7) The testable spectral band range is relatively wide, from 300nm to 2250nm, which can meet the measurement requirements of various different bandgap photovoltaic cells, such as various types of III-V semiconductor cells, including Si cells with a cutoff wavelength of 1100nm, GaSb cells with a cutoff wavelength of 1700nm, Ge cells with a cutoff wavelength of 1800nm, InGaAs cells with a cutoff wavelength of 2100nm, etc. The quantum efficiency test system of the present invention has a wide spectral range, can simultaneously measure the internal and external quantum efficiencies and reflectivity, has high accuracy, long service life, low manufacturing cost, and a convenient and fast test process, and proposes a new design scheme for the quantum efficiency test of photoelectric conversion devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is an overall schematic diagram of the quantum efficiency testing system of the present invention;

[0026] Figure 2 This is a structural diagram of the laser lamp bead turntable of the present invention;

[0027] Figure 3 It is a working principle diagram of a single chip microcomputer controlling a driving circuit in a reflectivity testing unit of the present invention;

[0028] Figure 4 It is a structural diagram of an integrating sphere in a reflectivity testing unit of the present invention;

[0029] Figure 5 This is a schematic diagram of the EQE test operation of the present invention;

[0030] Figure 6This is a schematic diagram of the reflectivity test operation of the present invention;

[0031] Figure 7 This is a test curve schematic diagram of Example 1 of the quantum efficiency test system of the present invention;

[0032] Figure 8 This is a test curve schematic diagram of Example 2 of the quantum efficiency test system of the present invention;

[0033] Fig. 9 This is a test curve schematic diagram of comparative example 1 of the quantum efficiency test system of the present invention;

[0034] Fig.10 It is a schematic diagram of the test curve of comparative example 2 of the quantum efficiency test system of the present invention. DETAILED DESCRIPTION

[0035] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0036] Embodiment 1:

[0037] The quantum efficiency testing system of the broadband photoelectric conversion device of the present invention has a structure as follows: Figure 1 As shown. The main body of the test system includes a test box and a computer 19 for collecting and processing data; the test box includes a box body 10, an external quantum efficiency test unit and a reflectivity test unit; the box body 10 is used to provide a closed and light-proof test environment. The external quantum efficiency test unit includes a first test light source 5, a laser power meter 2 and a digital source meter 3, the laser power meter 2 is used to measure the laser power of the first test light source, and the digital source meter 3 is used to measure the short-circuit current of the sample 7 in the external quantum efficiency test unit. The reflectivity test unit includes a second test light source 17, a scanning galvanometer 15, an integrating sphere 13 and a control drive circuit single chip microcomputer 18, the integrating sphere 13 is provided with a light detector 14, the output signal of the light detector 14 is sent to the control drive circuit single chip microcomputer 18, and the output voltage of the light detector 14 is obtained; the first test light source and the second test light source (5, 17) both use a multi-wavelength laser combiner. The test system also includes a power supply box 1 for providing power to the system.

[0038] The following is a detailed introduction to the design of each part:

[0039] (1) Test box 10: The quantum efficiency test box includes a rectangular light-proof sealed box 10, an EQE test unit and a reflectivity test unit. A box door for placing samples is set on the side of the box 10, and a telescopic door 8 is set in the middle of the box 10 to divide the functional areas of the two modules. The EQE test unit is located on the left side of the box. A first test light source 5 emitting near-infrared light of different bands is set on the top. The first test light source 5 adopts a laser lamp bead turntable (No. 1). A liftable test platform 6 for placing photoelectric conversion devices and a laser power meter probe 4 are set at the bottom. A hole is reserved at the bottom of the box for the special wires of Keithley source meter and laser power meter to pass through. The reflectivity test unit is located on the right side of the box, with a scanning galvanometer 15 that swings at a certain frequency on the top, fixed by a support arm 9, an integrating sphere 13 whose inner wall can diffusely reflect light, fixed by a stand 11, a light detector 14 and a storage table 12 for placing a photoelectric conversion device (sample 7), a second test light source 17 that emits near-infrared light of different bands is provided on the right side wall of the box, the second test light source 17 also uses a laser lamp bead turntable (No. 2), and a channel is reserved on the side wall of the box for the special wire of the light detector to pass through.

[0040] (2) Power supply box 1: The power supply box can provide the rated voltage required by laser lamp bead turntable No. 1, laser lamp bead turntable No. 2, and the control drive circuit microcontroller.

[0041] (3) Laser power meter 2: The laser power meter consists of a power display and a measuring probe, which are used together. The spectral response range of the laser power meter is 0.2 to 11 μm, which can cover the wavelengths of all laser lamp beads in the quantum efficiency test box. When performing power testing, its spectral response is flat, with high sensitivity (1 μm / 1 μJ), good resolution (100 μW), fast response speed (2s), good thermal stability, and long service life. The external display screen can intuitively read the power measurement value of the laser emitted by the lamp bead.

[0042] (4) Digital SourceMeter 3: Use Keithley SourceMeter. Keithley SourceMeter is a high-precision, high-resolution digital multimeter that can accurately measure the output current and voltage of the battery (photoelectric conversion device) under test.

[0043] (5) Control drive circuit single chip microcomputer 18: The control drive circuit single chip microcomputer integrates the modules such as the galvanometer driver, operational amplifier, and phase-locked amplifier required for the reflectivity test into a single chip. The photocurrent signal generated by the light detector when illuminated can be converted into a voltage signal through the amplifier circuit, and the test signal with the same frequency and phase as the reference signal can be amplified and phase-locked so that subsequent equipment can process the data. The working principle is as follows: Figure 3 shown.

[0044] (6) Computer 19: The computer should be installed with Keithley source meter test system software to record and process data such as the output current and voltage of the photoelectric conversion device. The computer can realize communication between the microcontroller and the computer through the serial port, control the microcontroller program, and record and process the output signal.

[0045] All the wires are special wires required for each device, including 1 laser lamp turntable (No. 1) power supply wire, 1 laser power meter special wire, 4 Keithley source meter special wires, 1 laser lamp turntable (No. 2) power supply wire, 1 scanning galvanometer drive line, 1 light detector output signal line, 1 microcontroller power line, and 2 USB adapter cables.

[0046] In the quantum efficiency test box EQE test unit, the laser lamp bead turntable (No. 1) includes 20 lamp bead brackets 21, the center points of the brackets overlap and are fixed with support columns, the angle between each bracket is 9°, and laser lamp bead mounting holes are set at both ends of each bracket; the laser lamp bead turntable No. 1 includes emitting monochromatic light with wavelengths of 300nm, 350nm, 400nm, 450nm, 500nm, 550nm, 600nm, 650nm, 700nm, 750nm, 800nm, 850nm, 900nm, 950nm, 1000nm, 1050nm, 11 100nm, 1150nm, 1200nm, 1250nm, 1300nm, 1350nm, 1400nm, 1450nm, 1500nm, 1550nm, 1600nm, 1650nm, 1700nm, 1750nm, 1800nm, 1850nm, 1900nm, 1950nm, 2000nm, 2050nm, 2100nm, 2150nm, 2200nm, 2250nm laser lamp beads, 40 in total, are installed on the bracket in ascending order of wavelength, see Figure 2 During the test, the lamp beads on one side of the same bracket are vertically aligned with the center point of the battery to be tested to measure the external quantum efficiency, and the lamp beads on the other side are vertically aligned with the center point of the laser power meter probe and the distance is appropriate to measure the laser power of the lamp beads. The rotation of the turntable is controlled by the gear device. Every time the turntable is turned, the adjacent lamp beads rotate to the top of the test area. The power value of each laser lamp bead is intuitively read by the external display screen of the laser power meter and recorded in sequence; the liftable test platform 6 can continuously adjust the vertical distance between the battery and the lamp bead.

[0047] In the reflectivity test unit of the quantum efficiency test box, the integrating sphere 13 is an ideal depolarization component. After the light enters the integrating sphere, it can form an ideal diffuse source. There are four holes in the sphere at appropriate positions, namely the incident laser hole 22, the light detector hole 23, the sample hole 24, and the observation hole 25. The holes can make the laser spot fully illuminate the sample under test. See the attached Figure 4 The scanning galvanometer is a high-reflection mirror coated with aluminum film, which can rotate periodically at a certain frequency within a small angle range. The incident laser generates two beams of light after reflection, which enter the inner wall of the integrating sphere and the sample under test. The light detector can detect the luminous flux of the incident light beam directly entering the integrating sphere and diffusely reflected, and the luminous flux of the incident light entering the integrating sphere and then diffusely reflected by the integrating sphere after being reflected by the mirror surface of the sample under test.

[0048] In the reflectivity test unit of the quantum efficiency test box, the lamp bead layout setting of laser lamp bead turntable No. 2 is the same as that of laser lamp bead turntable No. 1, including 1 monochromatic laser lamp bead with an emission wavelength of 300nm to 2250nm, a total of 40, which are installed on the bracket in ascending order of wavelength. The difference from turntable No. 1 is that the lamp bead bracket is shorter to ensure that the turntable diameter does not exceed the height of the test box to ensure the normal operation of the device; during the test, the turntable is controlled to rotate by a gear device. As the turntable is turned, the lamp beads that rotate to the top can emit monochromatic light in turn through the incident laser hole into the integrating sphere, and the laser light emitted by the lamp beads that rotate to the bottom is blocked by the baffle 16.

[0049] In the present invention, the relevant data required for calculating the EQE, IQE and R of the battery to be tested (photoelectric conversion device) can be obtained through the following operation steps:

[0050] (1) Open the door of the quantum efficiency test chamber and connect the wires required for the test;

[0051] (2) Place the battery to be tested on the sample position of the EQE test module test platform;

[0052] (3) Adjust the liftable test platform to ensure the appropriate distance between the battery and the lamp beads;

[0053] (4) Turn on the power box, laser power meter, Keithley source meter, laser lamp turntable (No. 1), and computer power supply;

[0054] (5) Rotate and turn the laser lamp bead turntable (No. 1). The laser power of each monochromatic laser lamp bead can be measured by the laser power meter and can be read directly on the display. The power of the lamp bead with a wavelength of 300nm to 2250nm is P 1 ~P 40 The short-circuit current (I) of the battery to be tested under near-infrared light of different wavelengths can be obtained in turn through the Keithley source meter and the computer. sc ), respectively

[0055] (6) Open the door of the quantum efficiency test chamber, lower the lifting platform, and take out the battery to be tested;

[0056] (7) Turn on the power box, single-chip microcomputer, laser lamp turntable (No. 2), and computer power;

[0057] (8) Adjust the laser beam so that only one of the two beams modulated by the scanning galvanometer can enter the integrating sphere. The light intensity measured at this time is the light intensity after diffuse reflection when the laser beam directly enters the inner wall of the integrating sphere, that is, the static DC output when the laser beam directly enters the integrating sphere.

[0058] (9) Rotate and turn the laser lamp bead turntable (No. 2) to obtain the static DC output of the integrating sphere under different wavelengths of near-infrared light, and convert the output into a test voltage through single-chip microcomputer processing.

[0059] (10) Open the door of the quantum efficiency test chamber and place the battery to be tested on the sample position of the reflectivity test module storage table;

[0060] (11) Under the condition of unchanged test conditions, observe and adjust the two test light beams through the observation hole of the integrating sphere so that one of the test light beams is irradiated on the battery under test, and the reflected light beam should also be reflected to the inner wall of the integrating sphere. At this time, the measured value is the tiny light intensity difference caused by the reflection of the battery under test;

[0061] (12) Rotate and turn the laser lamp bead turntable (No. 2) to obtain the illuminance difference under different wavelengths of near-infrared light, and convert it into a test voltage after processing by the single-chip microcomputer.

[0062] The data processing process in the present invention follows the following formula principle:

[0063] (1) It is known that the quantum efficiency of a battery in each wavelength band can be divided into external quantum efficiency and internal quantum efficiency. The external quantum efficiency is numerically equal to the ratio of the number of photogenerated minority carriers that can generate photocurrent to the number of all photons incident on the surface of the solar cell. Compared with the external quantum efficiency, the internal quantum efficiency deducts the influence of reflection factors and is numerically equal to the ratio of the number of photogenerated minority carriers that can generate photocurrent to the number of photons incident on the inside of the battery. Therefore, the internal quantum efficiency can be calculated from the spectral responsivity and surface reflectivity of the battery, while the external quantum efficiency can be directly calculated from the spectral responsivity combined with the incident light power measured by a laser power meter. The derivation process is as follows:

[0064] If the short-circuit current of the battery under light is I sc (λ), the incident light intensity is I light (λ), the spectral response value of the battery is:

[0065]

[0066] Therefore, the external quantum efficiency of the battery is:

[0067]

[0068] The internal quantum efficiency is:

[0069]

[0070] Among them, e is the electron charge, λ is the wavelength of the incident spectrum, h is Planck's constant, c is the speed of light in vacuum, and R is the reflectivity of the battery surface.

[0071] The incident light intensity I is known light (λ) refers to the light energy flux per unit area, measured in W / m 2 , describes the energy of light passing through a certain area per unit time during propagation. If the aperture of the laser power meter detector is d, and the incident light power measured at a specific wavelength is P(λ), then:

[0072]

[0073] From formula (2) and formula (4), we can know that:

[0074]

[0075] Assume constant k(λ) = πd 2 hc / 4eλ, the external quantum efficiency can be expressed as:

[0076]

[0077] From formula (3), we can see that the internal quantum efficiency can be expressed as:

[0078]

[0079] (2) According to the optical properties of the integrating sphere, if the reflectivity of the inner wall coating of the integrating sphere is R 0 , the luminous flux is φ 0 After the light beam directly enters the inner wall of the integrating sphere, the illuminance E at any position of the inner wall after multiple diffuse reflections in the integrating sphere is:

[0080]

[0081] Where r is the radius of the integrating sphere, f is the ratio of the opening area to the surface area of ​​the inner wall of the integrating sphere, then the luminous flux φ emitted from the detector hole is 1 for:

[0082] φ 1 =ES 0 (9)

[0083] Where S 0 is the opening area of ​​the detector hole. When the light beam is incident on the sample under test at the sample hole of the integrating sphere, the reflected luminous flux φ′ is:

[0084] φ′=R c φ 0 (10)

[0085] Where R c is the reflectivity of the sample under test. After the light beam is reflected by the sample under test onto the inner wall of the integrating sphere and then undergoes multiple diffuse reflections, the illuminance E' at any position on the inner wall is:

[0086]

[0087] The luminous flux emitted from the detector hole is 2 for:

[0088] φ 2 =E'S 0 (12)

[0089] If appropriate light detectors are used to test the emitted luminous flux φ 1 and φ 2 , then the reflectivity R of the sample under test c It is easy to find, namely:

[0090]

[0091] According to the uniform diffuse reflection characteristics of the integrating sphere, if the outgoing luminous flux value of the light beam diffusely reflected by the inner wall of the integrating sphere at the detector hole and the outgoing luminous flux value of the light beam after being reflected by the sample under test and then diffusely reflected by the integrating sphere are measured at the detector hole of the integrating sphere, the ratio of the two luminous fluxes is the reflectivity of the sample under test. Usually, after receiving light, the photodetector converts the luminous flux into a photocurrent or voltage value, which is then amplified and converted into voltage values ​​U and U' by the photoelectric conversion circuit. The ratio of the voltage values ​​corresponding to the two test light beams is also the reflectivity of the sample under test, that is:

[0092]

[0093] Furthermore, in the present invention, the relevant data obtained by the above operation steps can be calculated and sorted in a computer through the following data processing steps, and finally the EQE value, IQE value and reflectivity R value of the battery (photoelectric conversion device) to be tested are obtained and fitted and plotted as EQE, IQE and reflectivity curves:

[0094] (1) Assume that the external quantum efficiency of the battery under test in the 300nm~2250nm band is EQE 300nm ~EQE 2250nm It is known that the power of the lamp beads with wavelengths of 300nm to 2250nm measured by the laser power meter is P 1 ~P 40 , the short-circuit currents of the batteries to be tested are According to formula (6), the EQE value of the battery to be tested is:

[0095]

[0096] (2) Assume that the internal quantum efficiency of the battery under test in the 300nm to 2250nm band is IQE 300nm ~IQE 2250nm It is known that the voltage value obtained by converting the outgoing light flux measured by the integrating sphere detector into the detector hole after the light beam is diffusely reflected by the inner wall of the integrating sphere is The voltage value obtained by converting the outgoing light flux after the light beam is reflected by the sample and diffusely reflected by the integrating sphere is According to equations (7), (14) and (15), the IQE value of the battery to be tested is:

[0097]

[0098] (3) The surface reflectance values ​​of the battery under test in the 300nm to 2250nm band can also be obtained by formula (14): R 300nm ~R 2250nm :

[0099]

[0100] (4) The EQE value (EQE) obtained in the above steps is 300nm ~EQE 2250nm )、IQE value (IQE 300nm ~IQE 2250nm ) and R value (R 300nm ~R 2250nm ) is fitted in a computer to draw the EQE, IQE and reflectivity curves of the battery to be tested (photoelectric conversion device).

[0101] This embodiment provides an actual test operation process of a wide-band photoelectric conversion device quantum efficiency test system. The battery to be tested is a GaSb battery with a bandgap of 0.72 eV. The process specifically includes the following steps:

[0102] Step 1: EQE unit test

[0103] like Figure 5 The following is a schematic diagram of the EQE test operation. Place the GaSb battery to be tested on the EQE test unit test platform, connect the wires, adjust the position, turn on the power, rotate the laser lamp bead turntable (No. 1), and use the laser power meter to measure and read the lamp bead power P with wavelengths of 300nm to 2250nm in sequence. 1 1 , P 1 2 , P1 3 、P 1 4 、P 1 5 、P 1 6 、P 1 7 、P 1 8 、P 1 9 、P 1 10 、P 1 11 、P 1 12 、P 1 13 、P 1 14 、P 1 15 、P 1 16 、P 1 17 、P 1 18 、P 1 19 、P 1 20 、P 1 21 、P 1 22 、P 1 23 、P 1 24 、P 1 25 、P 1 26 、P 1 27 、P 1 28 、P 1 29 、P 1 30 、P 1 31 、P 1 32 、P 1 33 、P 1 34 、P 1 35 、P 1 36 、P 1 37 、P 138 , P 1 39 , P 1 40 The short-circuit current of the GaSb battery to be tested under 300nm~2250nm near-infrared light is measured by Keithley source meter

[0104] Step 2: Reflectivity Unit Test

[0105] like Figure 6 The figure shows the reflectivity test operation diagram. Connect the wires, adjust the position, turn on the power, adjust the two beams modulated by the scanning galvanometer to the appropriate position, and measure the static output voltage under 300nm~2250nm near-infrared light irradiation through the laser lamp bead turntable (No. 2) and the single-chip microcomputer.

[0106] And the output voltage after the light beam is reflected by the GaSb battery to be tested

[0107] Step 3: Computer data processing

[0108] Through computer processing, the EQE, IQE and reflectivity values ​​of the GaSb battery to be tested in the spectral range of 300nm to 2250nm can be obtained as follows:

[0109]

[0110] The EQE value, IQE value and R value obtained in the above steps are fitted in a computer to draw the EQE, IQE and reflectivity curve of the GaSb battery to be tested. See the attached Figure 7 .

[0111] Embodiment 2:

[0112] This embodiment provides an actual test operation process of a wide-band photoelectric conversion device quantum efficiency test system. The battery to be tested is an InGaAs battery with a band gap of 0.59 eV. The only difference between this embodiment and embodiment 1 is that the selected battery to be tested has a different band gap, and the other operations are the same as those of embodiment 1. The EQE value, IQE value and R value obtained through the test steps are fitted in a computer to draw the EQE, IQE and reflectivity curves of the InGaAs battery to be tested, see the attached Figure 8 .

[0113] Comparative Example 1:

[0114] like Fig. 9The figure shows a schematic diagram of the curve obtained when the external quantum efficiency of two GaSb batteries (1# and 2#) is tested separately using a domestic brand quantum efficiency meter. The principle of this type of quantum efficiency meter for measuring the external quantum efficiency of photoelectric conversion devices is as follows: when two batteries with different band gaps are irradiated with incident light of the same intensity and wavelength, the external quantum efficiency ratio is equal to the battery short-circuit current ratio. Therefore, the equipment is generally equipped with a calibrated standard semiconductor device as a reference for the EQE test results. This brand of quantum efficiency meter uses Si and Ge semiconductors as system standard reference devices, with cut-off wavelengths of 1100nm (Si) and 1800nm ​​(Ge) respectively. The cut-off wavelength is the longest wavelength at which the semiconductor material can effectively absorb or emit light, which is related to the band structure. Under this characteristic limitation, the maximum wavelength of the quantum efficiency curve that can be measured by the instrument is 1800nm.

[0115] When using this quantum efficiency meter to test wide-band photoelectric conversion devices, such as GaSb batteries (absorption band of 300nm to 1700nm), the instrument uses Si semiconductors as standard reference devices in the range of ≤1100nm and Ge semiconductors as standard reference devices in the range of 1100nm to 1800nm. After completing the test process, one EQE curve for each of the two bands can be obtained. Before the test data is used for subsequent material performance analysis, device design or other related research, the data needs to be processed, including smoothing to ensure the continuity of the EQE value and slope at the joints, using optimization algorithms to minimize fitting errors, etc. The final curve is as follows: Fig. 9 shown.

[0116] Analysis shows that the quantum efficiency curve obtained by this test method will have problems such as discontinuity at the splicing, questionable rationality of spectral response, and large fitting error. 2 The fitting effect is evaluated by methods such as value and residual analysis, which brings unnecessary errors and influences to subsequent analysis and research. In addition, the maximum measurable spectral range of this type of quantum efficiency tester is calibrated to 1800nm, which cannot meet the quantum efficiency test requirements of wide-band photoelectric conversion devices, such as InGaAs cells with a cut-off wavelength of 2100nm.

[0117] If the wide-band quantum efficiency test system of the present invention is used, the testable spectral band range is 300nm to 2250nm, which can meet the measurement requirements of various different bandgap photoelectric conversion devices. In addition, the test system can simultaneously measure the external quantum efficiency EQE, the internal quantum efficiency IQE and the surface reflectivity R. The curve is complete and smooth, and there is no need to splice the quantum efficiency curves measured by two detectors, which can ensure the high repeatability and accuracy of the measurement results, and open up a new technical solution for the quantum efficiency test of photoelectric conversion devices.

[0118] Comparative Example 2:

[0119] like Fig.10 The figure shows a curve diagram obtained when the external quantum efficiency of the same GaSb battery (3#) is measured using two quantum efficiency meters of the same brand as in comparative example 1. Device a has just left the factory, and device b has been frequently used for a period of time. The other structural components of the two devices are exactly the same.

[0120] Analysis shows that the EQE curve measured by device b has lower measurement accuracy, greater equipment noise, and significantly increased inconsistency in EQE test results compared to device a. The reason is that this brand of quantum efficiency meter uses Si and Ge semiconductors as system standard reference devices. As the frequency of equipment use increases and environmental factors such as temperature, humidity, dust, and stress affect the material properties of Si and Ge, they will inevitably decline over time, affecting their ability to respond to optical signals. The noise level of electronic components increases, the measurement results of the tester fluctuate, and the stability and accuracy of the equipment are greatly reduced. In order to reduce the impact of semiconductor device aging on the quantum efficiency tester, it is necessary to regularly calibrate or replace the device, which increases the maintenance cost of the equipment user.

[0121] If the wide-band quantum efficiency testing system of the present invention is adopted, there is no need to use a reference photoelectric conversion device in the test, which fundamentally avoids the problem of semiconductor device degradation affecting the measurement accuracy of the equipment and opens up a new technical solution for the quantum efficiency testing of photoelectric conversion devices.

Claims

1. A wide-band photoelectric conversion device quantum efficiency test system, characterized in that: The main body of the test system includes a test box and a computer for collecting and processing data; the test box includes a box body, an external quantum efficiency test unit and a reflectivity test unit; the box body is used to provide a closed and light-proof test environment; the external quantum efficiency test unit includes a first test light source, a laser power meter and a digital source meter, the laser power meter is used to measure the laser power of the first test light source, and the digital source meter is used to measure the short-circuit current of the sample in the external quantum efficiency test unit; the reflectivity test unit includes a second test light source, a scanning galvanometer, an integrating sphere and a control drive circuit single-chip microcomputer, the integrating sphere is provided with a light detector, the output signal of the light detector is sent to the control drive circuit single-chip microcomputer to obtain the output voltage of the light detector; the first test light source and the second test light source both use a multi-wavelength laser combiner.

2. The wide-band photoelectric conversion device quantum efficiency testing system according to claim 1, characterized in that: The test system is not calibrated using standard semiconductor devices prior to testing.

3. The wide-band photoelectric conversion device quantum efficiency testing system according to claim 1, characterized in that: The computer calculates the external quantum efficiency and internal quantum efficiency of the sample based on the collected laser power of lasers of different wavelengths, the short-circuit current of the sample under irradiation with lasers of different wavelengths, and the output voltage of the photodetector before and after the lasers of different wavelengths are reflected by the sample at the integrating sphere.

4. The wide-band photoelectric conversion device quantum efficiency testing system according to claim 3, characterized in that: The external quantum efficiency processing of the sample includes: the computer calculates the external quantum efficiency of the sample based on the laser power of lasers of different wavelengths collected and the short-circuit current of the sample under the irradiation of lasers of different wavelengths. The calculation formula is: In the formula, EQE λ is the external quantum efficiency of the sample under different wavelength laser irradiation; k λ is a constant term, k λ =πd 2 hc / 4eλ, where d is the aperture of the laser power meter detector, e is the electron charge, h is Planck's constant, c is the speed of light in vacuum, and λ is the wavelength; is the short-circuit current of the sample under laser irradiation of different wavelengths; P i It is the power value of laser lamp beads with different wavelengths of laser.

5. The wide-band photoelectric conversion device quantum efficiency testing system according to claim 3, characterized in that: The internal quantum efficiency processing of the sample includes: the computer calculates the internal quantum efficiency of the sample based on the laser power of different wavelengths of lasers collected, the short-circuit current of the sample under the irradiation of lasers of different wavelengths, and the output voltage of the photodetector before and after the lasers of different wavelengths are reflected by the sample at the integrating sphere. The calculation formula is: In the formula, IQE λ is the internal quantum efficiency of the sample under different wavelength laser irradiation; U *i U is the static DC output voltage when the laser beam is directly incident on the integrating sphere, that is, the output voltage of the photodetector when there is no sample involved in the reflection of lasers of different wavelengths at the integrating sphere; i It is the output voltage of the photodetector corresponding to the laser of different wavelengths reflected by the sample.

6. The wide-band photoelectric conversion device quantum efficiency testing system according to claim 3, characterized in that: The computer also calculates the reflectivity of the sample, including: the computer calculates the reflectivity of the sample based on the output voltage of the light detector before and after the lasers of different wavelengths are reflected by the sample at the integrating sphere, and the calculation formula is: In the formula, R λ is the reflectivity of the sample under different wavelengths of laser irradiation, U *i U is the static DC output voltage when the laser beam is directly incident on the integrating sphere, that is, the output voltage of the photodetector when there is no sample involved in the reflection of lasers of different wavelengths at the integrating sphere; i It is the output voltage of the photodetector corresponding to the laser of different wavelengths reflected by the sample.

7. The wide-band photoelectric conversion device quantum efficiency testing system according to claim 1, characterized in that: The digital source meter automatically scans and measures to obtain the IV curve of the sample, and sends the data to the computer. The computer processes the IV curve data to obtain the short-circuit current of the sample under the irradiation of lasers of different wavelengths. The computer controls the control drive circuit single-chip microcomputer through program control, so that the galvanometer drive circuit in the single-chip microcomputer controls the rotation of the scanning galvanometer in the reflectivity test unit. The control drive circuit single-chip microcomputer integrates the scanning galvanometer driver, operational amplifier, and phase-locked amplifier into a single chip, converts the photocurrent signal generated by the light detector when it is illuminated into a voltage signal through the amplifier circuit, and amplifies and phase-locks the test signal with the same frequency and phase as the reference signal. In the external quantum efficiency test unit, the sample is placed on a liftable test platform for testing, and the liftable test platform is used to continuously adjust the vertical distance between the sample and the first test light source.

8. The wide-band photoelectric conversion device quantum efficiency testing system according to claim 1, characterized in that: The integrating sphere is provided with a plurality of openings; the scanning galvanometer rotates periodically at a certain frequency, and the incident laser is reflected by the scanning galvanometer to form light rays of different directions, which are incident on the inner wall of the integrating sphere and the sample through the openings; the multi-wavelength laser combiner includes a plurality of laser lamp beads for providing near-infrared light in the wavelength range of 300nm to 2250nm; the test system also includes a power supply box for providing power to the system.

9. A method for testing the quantum efficiency of a broadband photoelectric conversion device, characterized in that: The following steps are involved: (1) The test system is not calibrated using standard semiconductor devices before testing; (2) The laser power of each monochromatic laser lamp bead in the multi-wavelength laser combiner of the external quantum efficiency test unit is measured in sequence by a laser power meter, and the short-circuit current of the sample under the irradiation of lasers of different wavelengths in the range of 300nm to 2250nm is measured in sequence by a Keithley source meter; (3) Debugging the scanning galvanometer; measuring the output voltage of the photodetector before and after the laser of different wavelengths at the integrating sphere is reflected by the sample in the range of 300nm to 2250nm by controlling the single chip microcomputer of the driving circuit; (4) Through computer processing, the external quantum efficiency value EQE, internal quantum efficiency value IQE and reflectivity value R of the sample in the spectral range of 300nm to 2250nm are obtained.

10. The method for testing quantum efficiency of a broadband photoelectric conversion device according to claim 9, characterized in that: The method also includes: (5) using a computer to fit the results of the external quantum efficiency value EQE, the internal quantum efficiency value IQE and the reflectivity value R, and drawing a curve graph of the EQE, IQE and R of the sample.

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