JP2011096845A - Solar cell evaluation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell evaluation device capable of measuring efficiency of conversion with high resolution. <P>SOLUTION: The solar cell evaluation device includes: a stage 2 which holds a solar cell 1; a rotary driving device 5 which rotates the stage at a predetermined pitch; a scanning device 3 which scans the solar cell using a linear scanning beam; a lighting device 4 which is disposed between the stage and scanning device and projects planar bias light toward the solar cell; a means 8 which detects an output current output from the solar cell; and a means 6 which calculates a current density distribution and efficiency of photoelectric conversion of the solar cell based upon the detected output current. The lighting device includes a lighting light source which emits the bias light, and a surface lighting device which is optically coupled to the lighting light source, arranged opposite the solar cell, and composed of an optically transparent material, and irradiates the solar cell with the planar bias light. The linear scanning beam 17 emitted by the scanning device is transmitted through the surface lighting device of the lighting means to be incident on a solar module on the stage. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solar cell evaluation device, and more particularly to a solar cell evaluation device capable of measuring the conversion efficiency of a solar cell with high resolution.

  In order to improve the yield in the production of solar cells, an evaluation device that can measure the conversion efficiency of the solar cells with high resolution is required. For example, when the impurity concentration of a specific semiconductor layer is locally increased, a recombination center is formed in the semiconductor layer, and a site where conversion efficiency is significantly reduced is formed. Similarly, when there is a defect in the semiconductor layer, the conversion efficiency is reduced locally and a defective product is generated. Since these problems are caused by the manufacturing process, an evaluation device that can measure the current distribution and conversion efficiency of the solar cell with high resolution is indispensable in order to understand the cause of the defect and improve the manufacturing process of the solar cell. is there.

  When trying to measure the current distribution of a crystalline solar cell module or thin-film solar cell connected in multiple stages, the measured light was irradiated to the measured solar cell module, and the generated current was detected and detected Conversion efficiency is determined based on the current distribution. On the other hand, if one of the cells connected in series during measurement is not irradiated with illumination light, the cell becomes in a high impedance state, and it becomes difficult to detect an accurate current distribution. Therefore, it is necessary to irradiate the entire module with bias light and generate a photoexcitation current sufficient to flow electron-hole pairs generated by irradiation of measurement light.

A solar cell evaluation apparatus that detects a current output by scanning the entire solar cell module with a measurement beam while illuminating with bias light is known (for example, see Patent Document 1). In this known solar cell evaluation apparatus, a solar cell module to be measured is arranged on a fixed stage, and an overall illumination light source that illuminates the entire module above it and a portion that performs spot illumination or line illumination on the module And a lighting device. During the measurement, illumination light is irradiated from the entire illumination light source to the entire surface of the module, and scanning is performed with a light spot or a line-shaped light beam while illuminating the entire module.
JP 2009-11115 A

  In the solar cell evaluation device described in Patent Document 1, the overall illumination light source that performs overall illumination and the partial illumination device that performs optical scanning are arranged at substantially the same height above the solar cell to be measured. The illumination light emitted from the entire illumination light source is incident obliquely with respect to the light incident surface of the solar cell. For this reason, a luminance distribution is formed on the surface of the solar cell module. There is a drawback that the entire solar cell module is not illuminated with uniform brightness. In this case, in order to obtain uniform overall illumination, it is necessary to arrange the overall illumination device at a position far away from the solar cell. However, if the overall lighting device is arranged at a position far away from the solar cell, there is a drawback that the device becomes large. In particular, when measuring a solar cell module of 1.8 m × 1.8 m, it is necessary to arrange the entire illumination device at a high position considerably away from the solar cell, which is problematic from the viewpoint of practicality.

  Also, with respect to the scanning beam, the light source that generates the scanning beam is disposed obliquely above the solar cell, so that the scanning beam is incident obliquely on the surface of the solar cell and enters the scanning position of the solar cell. Accordingly, a problem that the scanning spot diameter changes occurs. If the diameter of the scanning spot changes according to the position of the solar cell, it cannot be evaluated with high resolution. Similarly, when scanning using a line-shaped light beam, the scanning beam is obliquely incident on the solar cell, so that the width of the line-shaped scanning beam changes, which is problematic in terms of resolution. .

An object of the present invention is to realize a solar cell evaluation apparatus capable of measuring the conversion efficiency of a solar cell with high resolution.
Another object of the present invention is to provide a solar cell evaluation apparatus capable of measuring conversion efficiency with high resolution without increasing the size.

A solar cell evaluation device according to the present invention is a solar cell evaluation device for evaluating the photoelectric conversion efficiency of a solar cell,
A stage for holding a solar cell to be evaluated, a rotary drive device for rotating the stage at a predetermined rotation pitch, a scanning device for scanning a solar cell arranged on the stage with a line-shaped scanning beam, and the stage An illumination device that is disposed between the scanning device and projects a planar bias light toward the solar cell disposed on the stage, and means for detecting an output current output from the solar cell, and detected Means for calculating the current density distribution or photoelectric conversion efficiency of the solar cell based on the output current,
The illumination device includes an illumination light source that generates bias light, an optically coupled material that is optically coupled to the illumination light source, and is disposed to face the solar cell on the stage, and is configured by an optically transparent material. A planar illuminator that emits a planar bias light toward the
The scanning device scans parallel to the solar cell with a converging line-shaped scanning beam,
The linear scanning beam emitted from the scanning device passes through the planar illumination body of the illumination device and enters the solar cell on the stage.

  The gist of the present invention is that the solar cell is scanned in parallel with a converging line-shaped scanning beam, and an illumination device that irradiates planar bias light is disposed between the scanning device and the solar cell. It is in. In other words, by scanning the solar cell with a converging line-shaped scanning beam, it is possible to detect changes in the current distribution generated in the solar cell by light irradiation with high resolution, and to measure the conversion efficiency of the solar cell with high resolution. It becomes possible to do. On the other hand, during scanning with a line-shaped scanning beam, it is necessary to illuminate the entire surface of the solar cell with substantially uniform bias light. For this reason, in this invention, the illuminating device which consists of an optically transparent material and irradiates planar bias light toward a solar cell is arrange | positioned between a solar cell and a scanning device. Since the illumination device is made of a transparent material, the linear scanning beam emitted from the scanning device passes through the illumination device and enters the solar cell. As a result, the current distribution generated by the light beam scanning can be detected with high resolution.

  An illuminating device that irradiates the entire surface of a solar cell with bias light includes an illumination light source and a planar illuminator that irradiates a planar bias light toward the solar cell. The planar illumination body includes a plurality of optical fibers extending in the scanning direction of the linear scanning beam and a transparent plate that supports the optical fibers. By forming a V-shaped groove in the optical fiber, the bias light propagating through the optical fiber is totally reflected by the V-shaped groove and emitted toward the solar cell. In this case, since the optical fiber does not have a refractive action in the longitudinal direction, the line-shaped scanning beam passes through the optical fiber as it is and enters the solar cell. Therefore, even if a line-shaped scanning beam is projected toward the solar cell from above the planar illumination body constituted by the optical fiber, a focused illumination line having a line width of about several hundred μm is formed on the surface of the solar cell. Is possible.

  Further, the transparent plate that supports the optical fiber of the planar illuminator is made of a glass substrate having a refractive index larger than that of the optical fiber, and the glass substrate is used as a transparent adhesive for fixing to the optical fiber glass substrate. If a transparent adhesive having substantially the same refractive index as that of the optical fiber is used, the bias light propagating through the optical fiber is refracted between the optical fiber and the adhesive layer when emitted from the optical fiber toward the solar cell. Since it spreads in the direction orthogonal to the extending direction of the optical fiber by the action, a uniform luminance distribution is ensured in the direction orthogonal to the extending direction of the optical fiber.

  In the present invention, an illuminating device made of an optically transparent material is disposed between the solar cell on the stage and the scanning device, and planar bias light is emitted from the illuminating device toward the solar cell. Therefore, the entire surface of the solar cell can be scanned by the converging line-shaped scanning beam while irradiating the bias light having a substantially uniform luminance distribution over almost the entire surface of the solar cell. As a result, the conversion efficiency of the solar cell can be measured with high resolution. In addition, an illumination device that irradiates bias light is placed between the scanning device that scans the solar cell with a line-shaped scanning beam and the solar cell, so that conversion efficiency can be measured with high resolution without increasing the size. The

It is a diagram which shows the whole structure of the solar cell evaluation apparatus by this invention. It is a diagrammatic perspective view showing an example of a scanning device. It is a figure which shows an example of an illuminating device. It is a figure explaining operation | movement of a planar illuminating device. It is a figure which shows the method of forming a V-shaped groove | channel in an optical fiber.

FIG. 1 is a diagrammatic side view showing the overall configuration of a solar cell evaluation apparatus according to the present invention.
2 is a perspective view of the scanning device of FIG. 1, and FIG. 3 is a diagram showing an example of an illumination device that irradiates bias light. Moreover, FIG. 4 is a figure for demonstrating operation | movement of the planar illuminating device of an illuminating device. Referring to FIG. 1, a solar cell 1 to be evaluated is placed on a stage 2. As solar cells, for example, various solar cells such as thin-film solar cells and solar cell modules in which a plurality of solar cells are connected in series are evaluated. A scanning device 3 that scans the solar cell 1 with a linear light beam is disposed above the stage 2. Between the solar cell 1 and the scanning device 3, an illumination device 4 that illuminates the entire solar cell 1 with planar bias light is disposed. The portion of the illumination device 4 facing the stage is made of an optically transparent material. The illumination device 4 is always lit during the measurement period, and illuminates almost the entire surface of the solar cell with bias light having substantially uniform brightness. Therefore, the solar cell 1 is scanned with a line-shaped light beam while the entire surface thereof is illuminated with bias light having a uniform luminance.

  A motor 5 is connected to the rotary stage 2. The motor 5 rotates the rotary stage 2 by a predetermined rotation angle for each scan of the scanning device 3 under the control of the signal processing device 6. The rotation angle is set to 11.25 °, for example, and the stage is rotated 11.25 ° for each light beam scan, and the light beam scan is performed 16 times for a half circumference of the solar cell. Electrode terminals 7 a and 7 b are connected to solar cell 1. The current excited by the solar cell by the scanning of the line-shaped light beam and the illumination by the bias light is supplied to the current-voltage conversion circuit 8 through the electrode terminals 7a and 7b, converted into a voltage signal, and then applied to the signal processing device 6. Is output.

  The signal processing device 6 rotates the stage 2 by 11.25 °, performs light beam scanning 16 times for a half circumference of the solar cell, and stores output current data obtained for each scanning in a memory. The signal processing device 6 processes output current data using CT logic (Computed Tomography logic), obtains a current distribution generated in the solar cell by light beam scanning, and determines each part of the solar cell based on the obtained current distribution. The photoelectric conversion efficiency at is calculated. The obtained conversion efficiency distribution can be displayed on a monitor. Various types of logic such as ML-EM, MAP-EM, and MAP-EMR can be used as CT logic for calculating the current distribution.

  The configuration of the scanning device 3 will be described with reference to FIG. The scanning device 3 has a light source housing 10. A light source 11 that emits light having a spectrum close to the spectrum of sunlight, such as a xenon lamp, is disposed in the light source housing 10. The light emitted from the light source 11 enters the filter 12, and light having a spectrum close to that of sunlight is emitted. A plurality of filters can be arranged as the filter 12, and light having a desired wavelength can be selectively emitted according to the characteristics or structure of the solar cell to be evaluated. The light emitted from the light source housing enters the optical fiber bundle 13. The optical fiber bundle is an aggregate of a plurality of optical fibers and is an optical transmission body having flexibility. The light emitting ends of the optical fiber bundles 13 are linearly arranged along the first direction and are held by the light emitter 14. Accordingly, a linear light beam extending in the first direction is emitted from the light emitter 14.

  The line-shaped light beam emitted from the light emitter 14 is reflected by the plane mirror 15 and enters a cylindrical mirror (cylindrical mirror) 16. The cylindrical mirror 16 is a mirror that extends along a first direction and has focusing properties only in a second direction orthogonal to the first direction. Therefore, the line-shaped light beam emitted from the cylindrical mirror 16 enters the surface of the solar cell 1 perpendicularly as a line-shaped scanning beam 17 having a width of about 0.2 mm. Referring to FIG. 1, the light emitter 14, the plane mirror 15, and the cylindrical mirror 16 provided at the light emitting end of the optical fiber bundle 13 are integrally supported by a scanning head 18. Therefore, the line-shaped scanning beam focused from the scanning head 18 toward the solar cell 1 on the stage is projected vertically.

  Both end portions of the scanning head 18 are two guide belts (only one guide belt 19 is illustrated) running in a second direction orthogonal to the first direction which is the extending direction of the line-shaped scanning beam. Attach to. The two guide belts 19 are stretched around the two drive rollers 20a and 20b. A motor 21 is connected to one drive roller 20a, and the guide belt 19 is reciprocated in the direction of the arrow by driving the motor 21. Therefore, the scanning head 18 reciprocates in the second direction (arrow direction) by driving the motor 21, and the solar cell 1 on the stage extends in the first direction (direction orthogonal to the paper surface of FIG. 1). The line-shaped scanning beam 17 is scanned in parallel to the solar cell along a second direction (in-plane direction in FIG. 1) orthogonal to the first direction.

  3A and 3B are diagrams showing an example of the lighting device 4. FIG. 3A is a schematic plan view, FIG. 3B is a side view seen from the side, and FIG. 3C is an optical fiber extension. FIG. 3 is a diagrammatic cross-sectional view cut along a plane orthogonal to a current direction. The illumination device 4 includes first and second light sources 30a and 30b that emit bias light. A light source that emits light having a spectrum close to that of sunlight is used as the light source, and for example, a xenon lamp can be used. In addition, a filter can be arrange | positioned in front of the 1st and 2nd light source, and desired wavelength light can be radiate | emitted. An optical fiber bundle 31 that is an aggregate of a plurality of optical fibers is provided between the first light source 30a and the second light source 30b. For the sake of clarity, an assembly of seven optical fibers 32a to 32g is used, but an assembly of many optical fibers can be used as required. One end 31a of the optical fiber bundle 31 is bundled in a circle and optically coupled to the first light source 30a, and the other end 31b of the optical fiber bundle is also bundled in a circle and optically coupled to the second light source 30b. Accordingly, bias light is incident on each optical fiber of the optical fiber bundle from both ends, and the incident bias light propagates toward the other end. The middle part of the optical fiber bundle 31 is arranged in the same plane so as to be parallel to each other at a predetermined interval along the first direction (extending direction of the line-shaped scanning beam 17). Then, the optical fibers 32 a to 32 g arranged in parallel with each other are fixed on the optically transparent glass substrate 33 by using the transparent adhesive layer 34. As the glass substrate, a glass substrate having a refractive index (for example, 1.50) larger than the refractive index of the core of the optical fiber is used. As the transparent adhesive, a transparent adhesive having a refractive index substantially equal to the refractive index of the glass substrate is used. For example, a liquid silicone resin adhesive that cures at room temperature can be used. As shown in FIG. 3C, the thickness of the adhesive layer 34 is set at a height level near the center axis of the optical fiber 32 from the surface of the glass substrate 33.

  In this example, a plastic optical fiber is used as an optical fiber constituting the optical fiber bundle. As an example, a plastic optical fiber has a diameter of 500 μm, a core refractive index of 1.46, and a cladding refractive index of 1.40. The thickness of the clad is 7.5 μm. The arrangement interval of the optical fibers in the first direction is, for example, a pitch of 1.75 mm. When a large solar cell module having a size of 1.8 m × 1.8 m is to be measured, an optical fiber having a thickness of 1 mm can be used and the arrangement interval can be set to 3 mm. The line-shaped scanning beam is incident substantially perpendicular to the optical fiber and the transparent plate, and extends in a direction perpendicular to the extending direction of the optical fiber. Further, the optical fiber has no refractive action in the longitudinal direction. Therefore, the line-shaped scanning beam emitted from the scanning device is emitted without being refracted in the second direction by the optical fiber, and is incident as a line-shaped light beam focused on the solar cell 1 disposed on the lower side. The optical fiber has a refracting action in a direction perpendicular to the extending direction, but the line-shaped scanning beam 17 extends in a direction perpendicular to the optical fiber, and therefore a problem occurs even if it receives the refracting action. Absent.

  Next, the light emission action of the illumination device will be described with reference to FIG. 4A is a perspective view showing a configuration of an optical fiber according to the present invention, and FIG. 4B is a schematic view showing a propagation state of illumination light incident on the optical fiber, including the central axis of the optical fiber. It is a figure cut and shown by a plane. FIG. 4C is a view showing a distribution state of illumination light emitted from the optical fiber, and is a view cut along a plane orthogonal to the central axis of the optical fiber. As shown in FIG. 4A, the optical fiber according to the present invention has a core 35 and a clad 36 formed on the outer peripheral surface thereof, and a large number of V-shaped grooves 37 are continuous along the longitudinal direction thereof. Formed. The V-shaped groove is formed so that the V-shaped surface intersects the central axis of the optical fiber. Further, the depth of the V-shaped groove 37 is set so that the tip of the groove is located at the surface of the core 34. Further, the angle θ with respect to the central axis of the surface constituting the V-shaped groove is set to 15 to 25 °.

  When illumination light enters from both ends of the optical fiber, the illumination light propagates toward the other end side while being totally reflected at the interface between the core 35 and the clad 36. On the other hand, when light propagating in the core is incident on the V-shaped groove 37, a part of the light is totally reflected at the interface between the clad and air in the groove and propagates downward, and the lower clad , And passes through the adhesive layer 34 and the glass substrate 33 to be emitted. Another part of the light is emitted to the outside from the interface with the air in the V-shaped groove. The inventor measured the amount of light totally reflected by the V-shaped groove and emitted from the lower side, and the amount of light emitted directly from the V-shaped groove to the outside. 1 ratio. According to this experimental result, it is possible to emit a considerable amount of illumination light downward using the V-shaped groove.

The V-shaped grooves are formed at regular intervals along the central axis of the optical fiber. Alternatively, the interval between the V-shaped grooves is set to be large on the end side in the central axis direction, and the interval between the grooves is set to be narrow at the center of the optical fiber. Thus, by setting the interval between the V-shaped grooves, that is, the formation density appropriately, it is possible to obtain a substantially uniform luminance distribution also in the central axis direction of the optical fiber. Therefore, in the planar illuminating body constituted by the optical fiber array and the transparent plate,
By appropriately setting the interval between the V-shaped grooves, it is possible to irradiate bias light having a uniform luminance distribution in the axial direction of the optical fiber.

  Next, the effect | action of the adhesive agent which fixes an optical fiber to a glass substrate is demonstrated. In this example, as shown in FIG. 3C, the thickness of the adhesive layer 34 is a thickness from the surface of the glass substrate to the height level of the central axis of the optical fiber. Further, the refractive index of the adhesive is substantially equal to the refractive index of the glass substrate and is larger than the refractive index of the core of the optical fiber. In this structure, there is no air layer between the glass substrate 33 and the optical fiber cladding 36, and the illumination light totally reflected by the V-shaped groove 37 is formed between the optical fiber cladding 36 and the adhesive layer 34. It progresses toward the glass substrate side through the interface. Here, the refractive index of the cladding is 1.40, the refractive index of the adhesive layer is 1.50, and the refractive index difference is relatively small. Therefore, the amount of light reflected at the interface between the cladding and the adhesive layer is small, and the loss of bias light is reduced. On the other hand, when there is no adhesive layer, an air layer is interposed between the clad and the glass substrate, so that the light totally reflected by the V-shaped groove is the interface between the clad and the air layer and the air layer and the glass. Since it passes through the two interfaces with the substrate, the loss due to reflection at the two interfaces is large. Therefore, the adhesive layer 34 has an important significance from the viewpoint of effective use of bias light.

  Next, the light quantity distribution in a direction (first direction) orthogonal to the extending direction of the optical fiber will be described. FIG. 4C is a diagram illustrating a light amount distribution of light that is totally reflected by the V-shaped groove and emitted to the outside. In FIG. 4C, the broken line indicates the light amount distribution in the direction orthogonal to the extending direction of the optical fiber when no adhesive layer is present, and the solid line indicates the light amount distribution when the adhesive layer is present. Since the adhesive layer 34 having a refractive index larger than the refractive index exists on the outer periphery of the clad 36, the illumination light totally reflected by the V-shaped groove is refracted at the interface between the clad and the adhesive layer. Thus, the light is refracted at a large angle in the direction (first direction) orthogonal to the extending direction of the optical fiber and enters the glass substrate. Therefore, the bias light emitted from each optical fiber propagates to the glass substrate side while spreading more widely in the first direction. As a result, by appropriately setting the arrangement interval in the first direction of the optical fibers, it is possible to make the luminance distribution uniform in the direction perpendicular to the arrangement direction of the optical fibers of the bias light emitted from the planar illumination body. It is.

  As described above, a substantially uniform luminance distribution is obtained from the planar illumination body of the illumination device by appropriately setting the interval between the V-shaped grooves formed in the optical fiber and the arrangement interval in the first direction of the optical fiber. It is possible to irradiate the planar bias light.

  Next, a method for forming a V-shaped groove in the optical fiber will be described. The angle θ of the V-shaped groove is important from the viewpoint of securing the amount of light that is totally reflected. According to the results of experiments by the present inventors, the surface of the V-shaped groove is in relation to the central axis of the optical fiber. It has been found best to set the angle between 15 and 25 °. FIG. 5 is a diagram illustrating a method of forming a V-shaped groove. A cutting tool 40 having an apex angle of 60 ° is positioned with respect to the plastic optical fiber 32 so that the cutting edge is orthogonal to the central axis of the optical fiber, and a pressing force is applied. At this time, the acting pressing force is set to such a pressure that the tip of the blade tool 40 is in contact with the surface of the clad 36 of the optical fiber 32. Due to the pressing force of the blade tool, the clad is deformed into a V shape, and a V-shaped groove 37 is formed. As another method, a method using a gear can be used. As the gear, a gear whose apex angle of each tooth is set to 55 °, for example, is used, and the gear is moved in the longitudinal axis direction while pressing the gear against the optical fiber. Due to the pressure contact movement of the gear, a continuous V-shaped groove is formed in the clad of the optical fiber.

  Next, measurement of the luminance distribution of the line-shaped scanning beam will be described. If the line-shaped scanning beam has a luminance distribution, an error occurs in the detected current distribution. Further, if the luminance value itself of the line-shaped scanning beam changes, a problem occurs in the correction processing in the signal processing device. On the other hand, the emission intensity of the light source may vary depending on the temperature condition of the operating environment. Therefore, in the present invention, means for measuring the luminance distribution of the line-shaped scanning beam is provided, the luminance distribution of the line-shaped scanning beam is measured prior to the measurement of each sample, and the measurement result of the luminance distribution measurement is stored in advance in the signal processing device. Output. In the signal processing apparatus, the calculated current distribution is corrected using the luminance distribution and the value of the linear scanning beam measured in advance. With this configuration, an accurate current distribution can be output even if a partial luminance difference or luminance value fluctuates in the line-shaped scanning beam. Referring to FIG. 1, the photodetector 50 is disposed below the glass substrate 33 of the illumination device 4. The photodetector 50 is connected to a moving device 51 driven by a belt, and moves in a first direction which is an extending direction of the line-shaped scanning beam 17.

  At the time of measurement, the scanning head 18 is moved to the left end side in FIG. 1 and set so that the scanning beam 17 enters the photodetector 50. Further, the illumination device 3 is also operated, and light in which the bias light and the scanning beam are superimposed is incident on the photodetector 50. Subsequently, the photodetector 50 is moved along the first direction by the beam length of the scanning beam, during which the luminance distribution of the scanning beam is measured and output to the signal processing device 6. Thereafter, measurement with a line-shaped scanning beam is started. After the measurement is completed, the signal processing device 6 corrects the calculated current distribution using the luminance distribution of the scanning beam detected in advance and the absolute value thereof, and outputs the corrected current distribution.

  The present invention is not limited to the above-described embodiments, and various modifications and changes can be made. For example, in the above-described embodiment, an optical fiber array and a transparent plate are used as a planar illumination device that projects planar bias light toward a solar cell. It is also possible to use a plate-shaped optical waveguide having a two-layer structure in which a cladding layer having a refractive index is formed, or a plate-shaped optical waveguide having a three-layer structure in which a cladding layer having a low refractive index is formed on the upper side surface and the lower side surface. is there. In this case, by forming a groove with a V-shaped cross section in the upper clad layer, it is possible to emit illumination light totally reflected by the V-shaped groove as planar illumination light from the other surface. A planar illumination device is configured. Even when this optical waveguide is used, the optical waveguide itself is optically transparent. Therefore, when scanning with a line-shaped scanning beam from above, the surface of the solar cell is lined with bias light having a uniform luminance distribution. The light on which the scanning beam is superimposed enters. When the plate-shaped optical waveguide is used, the bias light emitted from the light source is converted into a line-shaped parallel beam and then incident on the plate-shaped optical waveguide. For example, an aluminum reflective layer is formed on the side surface of the plate-like optical waveguide.

  The lighting device described above can be used not only for a solar cell evaluation device but also as a surface lighting device for various applications, for example, as a backlight for an LCD display device or a laser display. It is.

  In the above-described embodiment, a V-shaped groove is formed in the clad of the optical fiber, and the bias light is emitted to the outside using total reflection on the surface of the V-shaped groove. Any shape and groove can be formed as long as the light propagating through the optical fiber is totally reflected. For example, a U-shaped groove or a curved concave portion is formed to form an optical fiber. It is also possible to emit propagating light to the outside.

DESCRIPTION OF SYMBOLS 1 Solar cell 2 Rotation stage 3 Scanning device 4 Illumination device 5 Motor 6 Signal processing device 7a, 7b Electrode terminal 8 Current-voltage conversion circuit 10 Light source housing 11 Light source 12 Filter 13 Optical fiber bundle 14 Light emitter 15 Plane mirror 16 Cylindrical mirror 17 Scanning beam 18 Scanning head 19 Drive belt 20a, 20b Drive roller 21 Motor 30a, 30b Light source 31 Optical fiber bundles 32a-32g Optical fiber 33 Glass substrate 34 Adhesive layer 35 Core 36 Cladding 37 V-shaped groove 40 Cutting tool 50 Photodetector 51 Moving device

Claims (14)

A solar cell evaluation apparatus for evaluating photoelectric conversion efficiency of a solar cell,
A stage for holding a solar cell to be evaluated, a rotary drive device for rotating the stage at a predetermined rotation pitch, a scanning device for scanning a solar cell arranged on the stage with a line-shaped scanning beam, and the stage An illumination device that is disposed between the scanning device and projects a planar bias light toward the solar cell disposed on the stage, and means for detecting an output current output from the solar cell, and detected Means for calculating the current density distribution or photoelectric conversion efficiency of the solar cell based on the output current,
The illumination device includes an illumination light source that generates bias light, an optically coupled material that is optically coupled to the illumination light source, and is disposed to face the solar cell on the stage, and is configured by an optically transparent material. A planar illuminator that emits a planar bias light toward the
The scanning device scans parallel to the solar cell with a converging line-shaped scanning beam,
The linear scanning beam emitted from the scanning device passes through the planar illumination body of the illumination device and is incident on the solar cell on the stage.   2. The solar cell evaluation apparatus according to claim 1, wherein the scanning device includes a light source device and a linear light beam conversion that converts a light beam emitted from the light source device into a linear light beam extending in a first direction. And a scanning means for scanning the linear light beam in a second direction orthogonal to the first direction.   3. The solar cell evaluation apparatus according to claim 2, wherein an optical fiber bundle is used as the line-shaped light beam converting means, and one end of the optical fiber bundle is optically coupled to the light source device to form an optical fiber bundle. The light emitting ends of the optical fiber bundles are linearly arranged along the first direction, and the linear light beam emitted from the light emitting end of the optical fiber bundle extends in the first direction and converges in the second direction. A solar cell evaluation apparatus, which is incident on a solar cell on a stage as a linear light beam that is incident on a cylindrical mirror having a beam and is focused in the second direction from the cylindrical mirror.   4. The solar cell evaluation apparatus according to claim 3, wherein the light emitting end and the cylindrical mirror of the optical fiber bundle are mounted on a scanning head, and are arranged on the stage by moving the scanning head in the second direction. A solar cell evaluation apparatus that scans a solar cell with a converging line-shaped light beam.   5. The solar cell evaluation device according to claim 1, wherein the light source device is a light source that generates scanning light, and the light emitted from the light source is converted into light having a spectrum close to the spectrum of sunlight. A solar cell evaluation apparatus comprising a filter for conversion. 2. The solar cell evaluation device according to claim 1, wherein the planar illuminating body of the illuminating device is arranged at a predetermined interval along a first direction that is an extending direction of the linear scanning beam. An optical fiber bundle including a plurality of optical fibers extending along a second direction that is a scanning direction of the scanning beam; and a transparent plate that supports the optical fibers arranged along the first direction. ,
One end of the optical fiber bundle is optically coupled to the illumination light source;
On the side away from the solar cell on the stage of each optical fiber, grooves or recesses that totally reflect the propagating light are continuously formed at predetermined intervals along the second direction,
The solar cell evaluation apparatus, wherein the bias light emitted from the illumination light source is emitted toward the solar cell on the stage while propagating through the optical fiber.   7. The solar cell evaluation apparatus according to claim 6, wherein a V-shaped groove is formed as a groove formed in the optical fiber, and a surface on which the V-shaped groove is formed intersects with the central axis of the optical fiber. A solar cell evaluation apparatus formed and having an angle of 15 to 25 degrees with respect to the central axis of the optical fiber.   8. The solar cell evaluation apparatus according to claim 6 or 7, wherein the line-shaped scanning beam emitted from the scanning apparatus is a line-shaped light beam that is focused by the optical fiber in the second direction with almost no refracting action. The solar cell evaluation apparatus characterized by being incident on the solar cell.   9. The solar cell evaluation apparatus according to claim 6, 7 or 8, wherein the optical fiber is a plastic optical fiber having a core and a clad formed on an outer peripheral surface of the core, and the transparent plate is made of plastic. A glass substrate having a refractive index larger than the refractive index of the core of the optical fiber is used, and each optical fiber of the optical fiber bundle is made of a glass substrate by a transparent adhesive layer having a refractive index substantially equal to the refractive index of the glass substrate. The light that is fixed to the V-shaped groove and totally reflected by the V-shaped groove spreads in a first direction orthogonal to the extending direction of the optical fiber by the refracting action between the optical fiber and the transparent adhesive layer. The solar cell evaluation apparatus characterized by emitting toward   The solar cell evaluation apparatus according to claim 9, wherein a liquid silicon-based adhesive is used as the transparent adhesive, and the adhesive layer has a height level at which the central axis of the optical fiber is located from the surface of the glass substrate. The solar cell evaluation device is formed so as to fill a space between optical fibers adjacent to each other up to the vicinity.   11. The solar cell evaluation device according to claim 6, wherein an illumination light source similar to the illumination light source is optical at the other end of the optical fiber bundle constituting the planar illumination device of the illumination device. The solar cell evaluation apparatus is characterized in that bias light is incident on both ends of the optical fiber.   The solar cell evaluation apparatus according to claim 11, wherein a formation interval of the V-shaped grooves formed in the optical fiber is gradually shortened from the end portion toward the central portion along the central axis of the optical fiber. The solar cell evaluation apparatus characterized by being set as follows.   13. The solar cell evaluation apparatus according to claim 1, further comprising: a luminance distribution measuring unit that measures a luminance distribution in a first direction of the linear scanning beam, wherein the luminance distribution measuring unit includes: The output signal is supplied to the signal processing device, and the signal processing device performs correction processing on the calculated current distribution using the output signal from the luminance distribution measuring means. An illumination device that emits planar illumination light,
An optical fiber array having a plurality of optical fibers arranged at predetermined intervals along the first direction and extending in a second direction orthogonal to the first direction; a transparent plate supporting the optical fiber array; And an illumination light source that is optically coupled to one end of the optical fiber array and supplies illumination light to the optical fiber. The optical fiber is transparent by a transparent adhesive having a refractive index substantially the same as the refractive index of the transparent plate. Fixed to the plate,
On the side away from the transparent plate of each optical fiber, a V-shaped groove is continuously formed along the second direction,
The illumination light supplied to the optical fiber array from the illumination light source is transmitted through the transparent plate from the side opposite to the side where the V-shaped groove is formed while propagating through the optical fiber, and is emitted to the outside.
Planar illumination light is emitted from the optical fiber array.

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