JP2010262951A - Solar cell and manufacturing method thereof - Google Patents

Abstract

In a solar cell having a current collecting structure that collects current generated on the light receiving surface and the back surface of the solar cell on the back surface side, a substrate for drawing the light receiving surface side electrode to the back surface is penetrated in the thickness direction. The characteristic defect due to the generation of a space inside the electrode is improved.
Deterioration of characteristics due to poor injection of conductive material into through-holes by providing a tapered shape in a through-hole that penetrates the substrate for drawing out the light-receiving surface side electrode of the solar cell to the back side in the thickness direction Can be improved. In addition, by using an intaglio offset printing method for forming an insulating film inside and around the through-hole and for forming an electrode on the light-receiving surface side, an extremely thin insulating film is formed on the entire wall surface of the through-hole without closing the through-hole. The effective light receiving area can be increased simultaneously with the formation of
[Selection] Figure 1

Description

  The present invention relates to a solar battery cell and a manufacturing method thereof.

  In many crystalline silicon solar cells, a p-type region or an n-type region is formed on one of the front and back surfaces of a silicon substrate, and an n-type region opposite to the one surface is formed on the other surface. Alternatively, a p-type region is formed. In general, electrodes are formed on the front and back surfaces of a silicon substrate, and on the light receiving surface side, a collecting electrode (bus bar electrode, finger electrode) for collecting the generated current is formed. Is a full surface electrode. It is important for the collector electrode on the light-receiving surface side to increase the cross-sectional area of the collector electrode in order to increase conductivity and reduce resistance loss. However, it is also important to reduce so-called shadow loss, in which incident light is blocked by the presence of the collector electrode. As described above, the following conventional techniques have been disclosed in response to the conflicting demands of reducing the resistance of the collector electrode and increasing the effective light receiving area of the solar battery cell.

  One is a structure in which a large number of minute through holes are provided in a silicon substrate and a pn junction is formed therein to contribute to photoelectric conversion (see, for example, Patent Document 1).

  The other is a so-called amorphous silicon layer sandwiched between a silicon substrate and an amorphous silicon layer, which reduces defects at the interface and improves the characteristics of the heterojunction interface. In a solar cell having a HIT (Heterojunction with Intrinsic Thin-layer) structure, when forming a current collecting structure that collects current generated on the light receiving surface on the back surface through the through hole, it is unnecessary around the through hole. In order to prevent the deposition of an amorphous silicon layer, a structure is shown in which an insulating film is formed on the inner wall surface of a through hole and then a conductive pair is filled (see, for example, Patent Document 2).

  The other one is a photovoltaic device having an insulating film with a thickness of about 1 to 10 μm formed on a translucent substrate (glass substrate), and the depth of the through-hole becomes deep in the insulating film. Accordingly, a method of forming a tapered through hole by a method of irradiating laser light while gradually reducing the size of the opening of the mask is disclosed (for example, see Patent Document 3).

Japanese Patent Laid-Open No. 2-51282 JP 2008-294080 A JP-A-6-260666

  However, in the invention described in Patent Document 1, a through hole having a diameter of about 100 μm is formed on a silicon substrate having a thickness of about 100 to 200 μm by irradiating laser light from a direction perpendicular to the substrate, Next, an invention is disclosed in which the crushed layer on the substrate surface is removed by chemical polishing. However, when an electrode metal layer is formed by screen printing or vapor deposition on the through hole, the depth of the through hole is reduced. On the other hand, if the diameter is small, the electrode material cannot be sufficiently injected into the through hole, and there is a possibility that a space exists and a conduction failure occurs.

  In the invention described in Patent Document 2, an insulating film is formed on the inner wall surfaces of a plurality of through holes that penetrate the silicon substrate and the amorphous silicon layers and transparent electrodes provided on the front and back of the silicon substrate. When filling the inside of the through hole with silver paste by the screen printing method, if the diameter is small with respect to the depth of the through hole, the electrode material cannot be sufficiently injected into the through hole and there is a space as described above. Insufficient conduction may occur.

  Further, when an insulating film is formed on the inner wall surface of the through hole by the CVD method, similarly, if the diameter is small with respect to the depth of the through hole, it is difficult to form the insulating film on the entire inner wall surface of the through hole. Further, if the insulating film formed on the inner wall surface of the through hole becomes too thick, the through hole may be blocked.

  In the invention described in Patent Document 3, it is possible to provide a tapered through-hole in an insulating film having a thickness of only about 1 to 10 μm. However, in a polycrystalline silicon substrate having a substrate thickness of about 350 μm. In application, the laser power must be extremely increased, and the slit for controlling the laser beam may melt. Even if the slit for controlling the laser beam does not melt, the periphery of the through-hole is easily damaged, and cracks or the like may occur in the substrate, which may induce substrate cracking.

Further, such a high-power laser device is expensive, leading to an increase in manufacturing cost. Therefore, it is extremely difficult or inefficient to provide a tapered through hole on a polycrystalline silicon substrate having a substrate thickness of about 350 μm by the method according to the invention described in Patent Document 3.

  Further, it is desirable to reduce the electrode area on the light receiving surface side as much as possible in order to improve the characteristics of the solar battery cell. However, as shown in the patent document, the light receiving surface side electrode is formed by screen printing. In this case, since the accuracy of the screen printing method is low, there is a possibility that the electrode area becomes too large and the effective light receiving area cannot be made sufficiently large.

  Furthermore, without forming the light receiving surface side electrode, the electrode material was injected into the through hole from the back surface side by screen printing, and the light receiving surface side electrode was formed so that the electrode material overflowed from the through hole on the light receiving surface side. In this case, it is difficult to control the area and shape of the light receiving surface side electrode, and there is a drawback in that a bonding failure between the light receiving surface side electrode and the back surface side electrode tends to occur.

  The present invention has been made to solve such a problem, and it is possible to sufficiently inject a conductive material into the shape of the through-hole while preventing damage to the substrate with a low-power laser device. In order to do so, the inner diameter on the back surface side is increased, and the inner diameter gradually decreases as it approaches the light receiving surface side. For example, a through hole having a large opening diameter of about 200 μm is formed while concentrating the laser power on a very small area of 5 μm in diameter and scanning.

  Further, the electrode formation on the light receiving surface side is reduced in size by the intaglio offset printing method, and the screen printing method having a sufficiently high printing pressure is used for the method of injecting the electrode material into the through hole from the back surface side.

  Furthermore, the insulating film is formed on the inner wall surface of the through-hole without obstructing the through-hole by printing and applying a highly viscous metal alkoxide compound material (about 0.2 to 0.5 μm) by intaglio offset printing. A very thin insulating film is formed on the entire inner wall surface of the through hole. Here, the metal alkoxide compound material is an inorganic coating-type SOG (Spin on Glass) material.

  A solar cell according to the present invention includes a semiconductor substrate, a polycrystalline semiconductor layer having a conductivity type formed on a main surface on the light receiving surface side of the semiconductor substrate, and a main surface on the light receiving surface side of the polycrystalline semiconductor layer. In a solar cell having a photoelectric conversion part formed of an antireflection film formed thereon, a tapered through hole having a gradually decreasing inner diameter from the back surface side to the light receiving surface side of the photoelectric conversion part is provided. is there.

  According to the present invention, when the electrode material is injected by making the through hole tapered, the electrode material can be sufficiently filled in the through hole without a gap, and the effective light receiving area can be sufficiently increased. it can. Thereby, the characteristic of a photovoltaic cell can be improved.

It is sectional drawing of the photovoltaic cell in Embodiment 1 of this invention. It is the figure which showed the manufacturing process of the photovoltaic cell in steps, and each figure (a)-(f) is the figure which showed each stage. It is the figure which showed the scanning method of a laser beam, (a) And (b) shows an example of the scanning method. It is the figure which showed the process of forming a taper-shaped through-hole using a scanning method in steps, and each figure (a)-(g) is the figure which showed each step. It is the figure which showed the outline of the energy distribution at the time of scanning a laser beam. It is the flowchart which showed the manufacturing process of the photovoltaic cell. It is the flowchart which showed the manufacturing process of the through-hole in detail. It is the microscope picture which showed the vertical cross section of the taper-shaped through-hole.

Embodiment 1 FIG.
Next, embodiments of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones. Therefore, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  1 is a cross-sectional view of a solar battery cell according to Embodiment 1 of the present invention. The solar cell 1 includes a photoelectric conversion unit 5 in which a p-type polycrystalline silicon substrate 2 that is a semiconductor substrate and an n-type polycrystalline silicon layer 4 are stacked. A semiconductor pn junction region is formed at the interface between the p-type polycrystalline silicon substrate 2 and the n-type polycrystalline silicon layer 4. Further, an antireflection film 3 made of a silicon nitride film is formed on the light receiving surface side of the photoelectric conversion portion 5 to constitute a solar cell substrate portion 10. Although the solar cell in Embodiment 1 of this invention has demonstrated the case where a polycrystalline-silicon substrate is used, you may be comprised with a single-crystal silicon substrate.

  The solar cell substrate portion 10 is provided with a plurality of tapered through holes 6 penetrating the p-type polycrystalline silicon substrate 2 and the n-type polycrystalline silicon layer 4 on which the antireflection film 3 is formed. A part of the back surface when the inner wall surface of the through hole 6 and the light receiving surface side main surface of the p-type polycrystalline silicon substrate 2 are the front surfaces (hereinafter, “front surface” is the light receiving surface side, and “back surface” is the light receiving surface side. The insulating film 7 is formed on the “back” in the case of “front”. The through hole 6 is filled with a conductor 8 made of a conductive material with an insulating film 7 interposed therebetween.

  The conductor 8 filled in the through hole 6 via the insulating film 7 plays a role of flowing the current generated on the light receiving surface of the solar cell substrate portion 10 to the back surface side. The current collected by the light receiving surface side electrode 9 is conducted to the back surface side of the solar cell substrate portion 10 by the conductor 8. In FIG. 1, only one through-hole 6 portion is shown for simplification, but usually a large number of solar cells 1 are formed over the entire area.

  Next, the manufacturing method of the photovoltaic cell in Embodiment 1 of this invention is demonstrated with reference to FIGS. FIG. 2 is a view showing the manufacturing process of the solar battery step by step, and each of the drawings (a) to (f) is a view showing each step. FIG. 3 is a diagram showing a laser beam scanning method, and FIGS. 3A and 3B show an example of the scanning method. FIG. 4 is a diagram showing steps of forming a tapered through hole using a scanning method, and FIGS. 4A to 4G are diagrams showing each step. FIG. 5 is a diagram showing an outline of an energy distribution when a laser beam is scanned. FIG. 6 is a flowchart showing the manufacturing process of the solar battery cell. FIG. 7 is a flowchart showing in detail the manufacturing process of the through hole in the manufacturing process shown in FIG. FIG. 8 is a photomicrograph showing a vertical cross section of the tapered through hole. Hereinafter, it will be described along the flow shown in FIG. 6 with reference to a predetermined diagram.

  In FIG. 2A, as the substrate of the solar battery cell 1, a p-type polycrystalline semiconductor substrate, for example, a p-type polycrystalline silicon substrate 2 doped with boron in a specific resistance of about 2 Ω · cm is used. The p-type polycrystalline silicon substrate 2 is immersed in, for example, a 10% aqueous sodium hydroxide solution in an alkaline solution heated to about 70 ° C. for about 10 minutes to etch the substrate surface. As a result, the damaged region generated near the surface of the p-type polycrystalline silicon substrate 2 at the time of slicing the substrate is removed and the surface of the p-type polycrystalline silicon substrate 2 is cleaned.

Next, anisotropic etching is performed at about 80 ° C. for 5 minutes in an alkaline solution, for example, a solution obtained by adding about 1% of an alcohol solution, for example, isopropyl alcohol, to a 10% aqueous sodium hydroxide solution as described above. carry out. This forms a texture shape on the surface. Thereafter, the substrate is heated at about 900 ° C. for about 20 minutes in a phosphorus oxychloride (POCl ₃ ) gas atmosphere. As a result, an n-type polycrystalline silicon layer 4 is formed on the surface of the p-type polycrystalline silicon substrate 2 and a semiconductor pn junction region is formed at the interface. Thereafter, the phosphor glass film formed on the surface of the polycrystalline silicon substrate is removed by immersing in an aqueous solution of about 5% hydrofluoric acid for about 5 minutes.

  In FIG. 2B, silicon nitridation is performed on the light-receiving surface side of the n-type polycrystalline silicon layer 4 formed as described above with silane, ammonia and nitrogen gas by plasma enhanced chemical vapor deposition (P-CVD). An antireflection film 3 made of a film is formed. When the refractive index and film thickness of the antireflection film 3 made of this silicon nitride film were measured by an ellipsometer, they were about 2.0 and about 80 nm, respectively. The solar cell substrate part 10 is formed by the above process. Thereafter, the back surface is etched.

  In FIG.2 (c), the through-hole 6 penetrated in the thickness direction of the solar cell substrate part 10 can be formed using a laser beam or a water jet. Here, a case where a through hole is formed using laser light will be described as an example. The through-hole 6 is formed by scanning laser light by a predetermined method from the back surface side to the front surface side of the solar cell substrate portion 10. Hereinafter, a method of forming the through hole 6 using this scanning method will be described in detail.

  3A and 3B are diagrams showing a laser beam scanning method. FIGS. 3A and 3B show an example of the scanning method. FIG. 3A shows a case where the laser beam is reciprocally scanned. FIG. 3B is a diagram showing a case where one-side scanning is performed.

  In this case, when the entire scanning surface is scanned in the course of scanning, the laser beam may be scanned at least partly of the portion that has been scanned once. Do not scan with. That is, when the entire scan surface is scanned once, there should be no unscanned portion. The frequency for scanning is about 20 Hz to 100 Hz, preferably about 30 Hz to 60 Hz, and more preferably about 40 Hz. The spot diameter of the laser beam is about 2 μm to 20 μm, preferably about 4 μm to 6 μm.

  Next, a process of forming a tapered through hole using the above scanning method will be described. FIG. 4 is a diagram showing steps of forming a tapered through hole using a scanning method, and FIGS. 4A to 4G are diagrams showing each step. In this case, the laser beam is irradiated in a plurality of times for each stage, and the scan area is gradually reduced in each stage. Hereinafter, for example, a case where the through-hole 6 having a thickness of the solar cell substrate 10 of 350 μm, an inner diameter on the back surface side of 200 μm, and an inner diameter of the front surface (light receiving surface) side of 20 μm will be described. Hereinafter, it will be described along the flow shown in FIG. 7 with reference to a predetermined diagram.

  The through-hole 6 is formed by using a fundamental wave of 1064 nm light from an Nd: YVO4 (yttrium, vanadium, oxide) solid-state laser, and continuously irradiating with irradiation light having a spot diameter of about 5 μm at an output of about 30 kW. Implement in the form.

  In FIG. 4 (a), the depth of the hole is about 50 μm by a reciprocating scan shown in FIG. 3 (a) in a circle having a diameter of about 200 μm at a predetermined position on the back surface side of the solar cell substrate 10. Scan continuously until The hole formed at this time has a columnar shape having a trapezoidal vertical section with an inner diameter of about 200 μm on the bottom surface (rear surface) side and an inner diameter of about 175 μm on the upper surface (front surface) side. Here, the taper shape having a trapezoidal vertical cross section is that when the laser beam is scanned, the energy distribution becomes higher in the central portion of the scan region, that is, in the central portion of the circle having a diameter of about 200 μm. This is because the temperature of the battery substrate portion 10 becomes high and the melting proceeds quickly. An outline of the energy distribution when the laser beam is scanned is shown in FIG.

  Similarly, by continuously scanning in a concentric circle having a diameter of about 175 μm until the depth of the hole reaches about 50 μm, the inner diameter on the bottom surface (back surface) side is about 175 μm, and the top surface (front surface) side. A cylindrical hole having a trapezoidal vertical cross section with an inner diameter of about 150 μm is obtained. As a result, as shown in FIG. 4B, the bottom surface (back surface) side has an inner diameter of about 200 μm, the top surface (front surface) side has an inner diameter of about 150 μm, and the depth is about 100. Get a hole. Thereafter, the same method is repeated.

  By continuously scanning a concentric circle with a diameter of about 150 μm until the hole depth is about 50 μm, the inner diameter on the bottom (back) side is about 150 μm and the inner diameter on the top (front) side is about A cylindrical hole having a trapezoidal vertical section of 123 μm is obtained. As a result, as shown in FIG. 4C, the inner surface on the bottom surface (back surface) side is about 200 μm, the inner surface on the top surface (front surface) side is about 123 μm, the depth is about 150, and the vertical section has a trapezoidal shape. Get a hole.

  By continuously scanning a circle with a diameter of about 123 μm concentrically until the hole depth is about 50 μm, the inner diameter on the bottom (back) side is about 123 μm, and the inner diameter on the top (front) side is about A cylindrical hole having a trapezoidal shape with a vertical cross section of 97 μm is obtained. As a result, as shown in FIG. 4D, the bottom surface (back surface) side has an inner diameter of about 200 μm, the upper surface (front surface) side has an inner diameter of about 97 μm, and the depth is about 200. Get a hole.

  By continuously scanning a concentric circle with a diameter of about 97 μm until the hole depth is about 50 μm, the inner diameter on the bottom (back) side is about 97 μm and the inner diameter on the top (front) side is about A columnar hole having a trapezoidal vertical section of 71 μm is obtained. As a result, as shown in FIG. 4E, the inner surface on the bottom surface (back surface) side is about 200 μm, the inner surface on the top surface (front surface) side is about 71 μm, the depth is about 250, and the vertical section has a trapezoidal shape. Get a hole.

  By continuously scanning a concentric circle having a diameter of about 71 μm until the hole depth is about 50 μm, the inner diameter on the bottom surface (back surface) side is about 71 μm, and the inner diameter on the top surface (front surface) side is about A cylindrical hole having a trapezoidal cross section of 46 μm is obtained. As a result, as shown in FIG. 4F, the bottom surface (back surface) side has an inner diameter of about 200 μm, the upper surface (front surface) side has an inner diameter of about 46 μm, and the depth is about 300, and the vertical section has a trapezoidal shape. Get a hole.

  By continuously scanning a concentric circle with a diameter of about 46 μm until the depth of the hole reaches about 50 μm, the inner diameter on the bottom (back) side is about 46 μm and the inner diameter on the top (front) side is about A cylindrical hole having a trapezoidal shape with a vertical cross section of 20 μm is obtained. As a result, a through-hole 6 having a trapezoidal vertical section with an inner diameter of about 200 μm on the bottom surface (back surface) side and an inner diameter of about 20 μm on the upper surface (front surface) side is obtained as shown in FIG.

  At this time, the outer angle indicated by the back surface of the solar cell substrate 10 and the inner surface of the through hole 6 is approximately 104.4 degrees as shown in FIG. Through the steps described above, the tapered through hole 6 is obtained. FIG. 8 is a photomicrograph showing a vertical cross section of the tapered through-hole 6 obtained by the method described above. As described above, it can be seen that a clean tapered through-hole 6 can be obtained in spite of stepwise scanning.

  The tapered through-hole 6 formed by this method can be provided without being restricted by the thickness of the solar cell substrate portion 10, but for a thin substrate having a thickness of 10 μm or less, A tapered through-hole can also be provided by a method as shown in Patent Document 3. In addition, when the thickness exceeds 500 μm, many scans are repeated until a through hole is obtained, which requires a lot of time and labor and is not efficient. Therefore, the invention shown in this embodiment is effective when the solar cell substrate portion 10 has a thickness of about 50 μm to 500 μm.

  Next, a process for forming the insulating film 7 will be described. In FIG. 2D, for example, an inorganic coating-type SOG (Spin on Glass) material is formed by intaglio offset printing with a thickness of about 2.0 to 3.0 μm, and the inner wall surface of the through hole 6 and the back surface side of the through hole 6. The insulating film 7 is formed by printing on the periphery and drying by heating in a drying furnace at about 450 ° C. Thus, by forming the insulating film 7 using the intaglio offset printing method, the extremely thin insulating film 7 can be uniformly formed without blocking the through-hole 6.

  Next, the process of filling the conductor 8 will be described. In FIG.2 (e), for example, the conductive paste material using the conductive metal powder which has aluminum as a main component from the back surface side of the solar cell substrate part 10 is printed in the through-hole 6 part using the screen printing method. The back side electrode 11 is formed simultaneously with filling the inside of the through hole 6 with the conductive paste material. Here, since the through hole 6 has a taper shape, even when the screen printing method is used, the ratio of the thickness of the solar cell substrate 10 and the inner diameter of the back surface of the through hole 6 is 1/1 or more, that is, the through hole 6 Even if the inner diameter of the back surface side of the hole 6 is less than the thickness of the solar cell substrate portion 10, the inside of the through hole 6 can be easily filled with the conductive paste material without a gap. Thereafter, the conductive paste material is dried and solidified in a drying oven at about 150 ° C.

  Here, if the outer angle formed by the back surface of the solar cell substrate portion 10 and the inner surface of the through-hole 6 is too close to a right angle, it is difficult to fill the conductive paste material without gaps as shown in Patent Document 1. It becomes. In addition, if the angle is too large, the amount of the conductive paste material increases, and the area of the back side electrode formed by the back side exposed portion of the conductor 8 obtained by drying and solidifying the conductive paste material increases. This is not efficient because the cell conversion efficiency of the solar battery is reduced. Therefore, the angle of the outer angle formed by the back surface of the solar cell substrate portion 10 and the inner surface of the through hole 6 is preferably about 100 ° to 120 °, and further, the angle shown in the first embodiment is 104.4 °. That is, an angle of around 105 ° is optimal.

  Next, a process of forming the light receiving surface side electrode 9 will be described. In FIG.2 (f), for example, the conductive metal powder which has silver as a main component with the thickness of about 2.0-3.0 micrometers by the intaglio offset printing was used for the light-receiving surface side of the solar cell board | substrate part 10. FIG. A conductive paste material is printed to form the light receiving surface side electrode 9. Here, the light receiving surface side electrode 9 forms a circular electrode having a diameter slightly larger than the light receiving surface side inner diameter of the through hole 6, that is, a diameter large enough to cover the exposed surface of the insulating film 7 on the light receiving surface side. As a result, contact with the light receiving surface side of the solar cell substrate 10 is obtained.

  Here, the light-receiving surface side electrode 9 is shown as a circular electrode, but this is because the minimum area where the contact with the light-receiving surface side of the solar cell substrate 10 can be effectively obtained is circular. It is because it is obtained and may have a polygonal shape such as a quadrangular shape or a triangular shape as long as a contact with the light receiving surface side of the solar cell substrate portion 10 can be obtained.

  As described above, the light-receiving surface side electrode 9 is formed by the intaglio offset printing method because a spot-like electrode can be formed with high accuracy, so that not only an increase in area due to paste bleeding is prevented, but also a small area This is because the light receiving surface side electrode 9 can be formed. For this reason, there exists an effect which increases the effective area of the photovoltaic cell 1, and improves a performance.

  Then, the light-receiving surface side electrode 9 and the back surface side electrode 11 are baked at about 800-900 degreeC. At this time, the light receiving surface side electrode 9 penetrates the antireflection film 3 and is electrically connected to the n-type polycrystalline silicon layer 4, whereby the solar battery cell 1 is obtained.

  As described above, when the solar battery cell 1 is manufactured, a highly efficient current collecting structure type solar battery cell 1 that collects both the current efficiently generated on the light receiving surface and the back surface on the back surface side can be obtained. .

  In the first embodiment, the process of forming the tapered through-hole 6 with the laser beam has been described in detail. However, the tapered through-hole 6 can also be obtained by the method of scanning the water jet. The setting conditions in this case are different design items depending on the hardness of the polycrystalline semiconductor substrate, the accuracy of the through-hole 6 and the like.

  DESCRIPTION OF SYMBOLS 1 Solar cell, 2 p-type polycrystalline silicon substrate, 3 Antireflection film, 4 n-type polycrystalline silicon layer, 5 Photoelectric conversion part, 6 Through-hole, 7 Insulating film, 8 Conductor, 9 Light-receiving surface side electrode, 10 Solar cell substrate 11 Back side electrode

Claims (5)

  A semiconductor substrate, a polycrystalline semiconductor layer having a conductivity type formed on the light-receiving surface side main surface of the semiconductor substrate, and an antireflection film formed on the light-receiving surface side main surface of the polycrystalline semiconductor layer In a solar battery cell having a solar cell substrate portion, a tapered through hole having a gradually decreasing inner diameter is provided from the back surface side to the light receiving surface side of the solar cell substrate, and a conductive material is interposed in the through hole through an insulating film. A solar battery cell characterized by being filled.   The photovoltaic cell according to claim 1, wherein the photoelectric conversion portion has a thickness of 50 μm to 500 μm.   3. The solar cell according to claim 1, wherein an outer angle formed by an inner wall surface of the tapered through hole and a back surface of the solar cell substrate portion is 100 degrees to 120 degrees. cell.   2. The solar cell according to claim 1, wherein the tapered through-hole is obtained by scanning a laser beam a plurality of times in the same region, and gradually reducing an area occupied in the same region. Production method.   5. The method for manufacturing a solar cell according to claim 4, wherein the scan does not include a portion that is not irradiated with the laser light in the same region.

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