JP4001260B2 - Solar cell manufacturing method and solar cell - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solar cell manufacturing method and a solar cell, and more particularly to a solar cell manufacturing method and a solar cell using spherical cells.
[0002]
[Prior art]
An internal electric field is generated at the pn junction portion of the semiconductor. When light is applied to the semiconductor to generate an electron-hole pair, the generated electron and hole are separated by the internal electric field, and the electron is positively connected to the n side. The holes are collected on the p side, and when a load is connected to the outside, a current flows from the p side to the n side. Utilizing this effect, solar cells are being put to practical use as elements that convert light energy into electrical energy.
[0003]
In recent years, a technique for manufacturing a semiconductor element by forming a circuit pattern on a spherical semiconductor (Ball Semiconductor) having a diameter of 1 mm or less such as single crystal or polycrystalline silicon has been developed.
[0004]
As one of them, a method for manufacturing a solar array in which a large number of semiconductor particles are connected using aluminum foil has been proposed (Japanese Patent Laid-Open No. 6-13633). In this method, as shown in FIG. 6, semiconductor particles 207 having an n-type skin portion and a p-type interior are arranged so as to protrude from both sides of the aluminum foil 201 in the opening of the aluminum foil, and the skin portion 209 on one side is removed. Then, the insulating layer 221 is formed. Next, a part of the p-type interior 211 and the insulating layer 221 thereon are removed, and the second aluminum foil 219 is bonded to the removed region 217. The flat region 217 provides good ohmic contact with the second aluminum foil 219 serving as a conductive portion.
[0005]
[Problems to be solved by the invention]
However, in such a conventional solar cell (the above solar array), an opening is formed by punching the aluminum foil 219 with a punch or the like, and the semiconductor particles 207 are embedded in the opening of the aluminum foil 219. For this reason, the semiconductor particles 207 had to be embedded after being accurately aligned with the opening of the aluminum foil 219. Further, in order to prevent a gap from being formed between the edge of the opening and the spherical cell at the time of embedding, it is required that the semiconductor particle 207 which is a sphere is a true sphere having a spherical shape and a constant diameter.
Therefore, the conventional solar cell manufacturing method and the solar cell as described above have a problem that the manufacturing method is difficult and the manufacturing cost increases.
[0006]
The present invention has been made in view of the above problems, and a low-cost and simple method for manufacturing a solar cell that can be manufactured even if the spherical cell of the solar cell is not precisely aligned or a uniform true sphere. An object is to provide a solar cell.
[0007]
[Means for Solving the Problems]
First method of manufacturing a solar cell of the present invention, the spherical surface of the substrate having a first conductivity type semiconductor layer, the manufacturing method of a solar cell using a spherical cell obtained by forming the second conductivity type semiconductor layer, flat Forming a transparent conductive layer on a transparent member to form a transparent substrate having flat upper and lower surfaces; and placing the spherical cell on the transparent substrate and pressing the transparent substrate and the spherical body A step of adhering the cell with a transparent conductive adhesive layer, a step of melting a transparent resin having electrical insulation, pouring until a part of the spherical cell is exposed from the liquid surface, curing, and forming a transparent insulating layer; Etching the second conductive type semiconductor layer of the spherical cell exposed from the transparent insulating layer to expose the first conductive type semiconductor layer inside; and on the transparent insulating layer and the spherical cell ; said first conductive exposed in the sphere cells A step of forming an insulating layer by applying an insulating member so that a part of the center of the type semiconductor layer remains exposed, and an exposed side of the first conductive type semiconductor layer on the transparent insulating layer And a step of forming a transparent conductive layer on the surface.
According to this method, without the need for precise positioning of the spheres cell, spherical shape and the diameter of the sphere cells may not be constant true sphere, even if there are variations in the shape or diameter can be manufactured. Further, it can be arranged in an arbitrary shape by an arrangement method such as an aggregation type arrangement method, a lattice arrangement method, or a staggered arrangement method. Further, since the conductive layer can be formed of an aluminum thin film (since the aluminum thin film has high reflection efficiency), the reflected sunlight can be taken into the spherical cell.
Moreover, since the transparent substrate used as an outer electrode, the flat transparent member of the outer layer, and the transparent conductive layer used as an inner electrode are transparent, a solar cell in which both the front and back surfaces are light receiving surfaces can be manufactured.
[0008]
The method of manufacturing a second solar cell of the present invention, the spherical surface of the substrate having a first conductivity type semiconductor layer, the manufacturing method of a solar cell using a spherical cell obtained by forming the second conductivity type semiconductor layer, flat Forming a transparent conductive layer on a transparent member to form a transparent substrate having flat upper and lower surfaces; and placing the spherical cell on the transparent substrate and pressing the transparent substrate and the spherical body a step of adhering the cells in the transparent conductive adhesive layer, a step of the transparent resin having an electrical insulation is melted, poured so that all portions of the spherical body cell is filled, cured to form a transparent insulating layer, wherein as the first conductive semiconductor layer from the transparent insulating layer inside the sphere cell is exposed, said a step of grinding to remove surface of the transparent insulating layer and sphere cells, through holes communicating only to the first conductive semiconductor layer An insulating member having the transparent insulation. It stuck on the layer and the surface of the spherical body cells, comprising the steps of a perforated insulating layer, covered with a transparent conductive member the surface of the insulating member, and is filled with the transparent conductive member in the through-hole, a transparent conductive layer Forming the step.
According to this method, without the need for precise positioning of the spheres cell, spherical shape and the diameter of the sphere cells may not be constant true sphere, even if there are variations in the shape or diameter can be manufactured. Further, it can be arranged in an arbitrary shape by an arrangement method such as an aggregation type arrangement method, a lattice arrangement method, or a staggered arrangement method. Further, since the conductive layer can be formed of an aluminum thin film (since the aluminum thin film has high reflection efficiency), the reflected sunlight can be taken into the spherical cell.
Furthermore, since the process of forming the insulating layer is only attaching an insulating member having a through hole, a process such as a melting / curing process of the insulating resin is not required, and the manufacturing can be facilitated.
Moreover, since the transparent substrate used as an outer electrode, the flat transparent member of the outer layer, and the transparent conductive layer used as an inner electrode are transparent, a solar cell in which both the front and back surfaces are light receiving surfaces can be manufactured.
[0009]
In the third solar cell of the present invention, a spherical cell having a first conductive type semiconductor layer inside and a second conductive type semiconductor layer on the inside is a flat transparent lower conductive layer, insulating layer, and transparent insulating layer in order from the lower layer. The first conductive layer of the spherical cell is formed by partially cutting away the second conductive type semiconductor layer and embedding it in a flat upper and lower flat substrate on which a flat upper transparent conductive layer and a flat transparent member are laminated. type semiconductor layer is an inner electrode formed by is flat the lower transparent conductive layer electrically connected to the substrate, the flat the upper transparent of said second conductivity type semiconductor layer and the substrate of the spherical cells by being conductive layer electrically connected to the outer electrode is formed by the insulating layer and the transparent insulating layer, in that said lower transparent conductive layer and the upper transparent conductive layer are electrically insulated Features.
[0010]
According to such a configuration, a simple structure is easy to manufacture, does not occur short circuit of the inner electrode and the outer electrode is essentially also as a light-receiving surface with the front and back of the double-sided, these inner, outer Both of the electrodes are transparent, and a solar cell with excellent light receiving efficiency can be realized by the transparent insulating layer provided on the light receiving surface.
[0011]
According to a fourth solar cell of the present invention, in the solar cell according to claim 3, a through-hole communicating only with the first conductive type semiconductor layer of the spherical cell is formed in the insulating layer, and the lower transparent conductive material is formed. The layer is laminated on the outer surface of the insulating layer so as to fill the through hole, and is an inner electrode having a flat outer surface .
According to such a configuration , the inner electrode and the outer electrode have a simple structure that is easy to manufacture, and the short circuit between the inner electrode and the outer electrode does not occur basically. Both are transparent, and a solar cell with excellent light receiving efficiency can be realized by a transparent insulating layer provided on the light receiving surface.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a solar cell and a method for manufacturing a solar cell according to the present invention will be described in detail with reference to the drawings.
[0013]
As shown in FIG. 1, the solar cell according to the embodiment of the present invention has a conductive layer 17 (for example, formed of an aluminum thin film, ITO, or the like) from the bottom, as shown in FIG. Insulating layer 16 (for example, formed of epoxy resin or the like), transparent insulating layer 15, transparent conductive layer 13 (for example, formed of ITO or the like), and transparent member 14 are stacked in solar cell substrate 20. It is formed so as to embed a spherical cell 10 to be a solar battery cell.
[0014]
The cross-sectional structure of the solar cell will be described in more detail. FIG. 2 shows a cross section taken along line AA of FIG. As shown in FIG. 2, a spherical cell 10 having an n-type semiconductor layer 12 (second conductivity type semiconductor layer) that forms a pn junction with an internal p-type semiconductor layer 11 (first conductivity type semiconductor layer) is described above. As shown, the flat conductive layer 17, the insulating layer 16, the transparent insulating layer 15, the flat transparent conductive layer 13, and the flat transparent member 14 are embedded in the stacked solar cell substrate 20 in the upper and lower surfaces in order from the lower layer. It is formed as follows.
[0015]
In the above configuration, the conductive layer 17 and the p-type semiconductor layer 11 are configured to be electrically connected. Thereby, the conductive layer 17 is an inner electrode of the solar cell. The transparent conductive layer 13 is configured to be electrically connected to the n-type semiconductor layer 12. Thereby, the transparent conductive layer 13 is an outer electrode of the solar cell.
[0016]
Further, the conductive layer 17 (inner electrode of the solar cell) and the transparent conductive layer 13 (outer electrode of the solar cell) are electrically insulated by the transparent insulating layer 15 and the insulating layer 16.
[0017]
Next, an example of a specific method for manufacturing a solar cell according to an embodiment of the present invention will be described below.
First, an example of a method for forming the spherical cell 10 used in the present embodiment will be described.
A p-type polycrystalline silicon particle having a diameter of 1 mm is dropped while being heated in a vacuum to form a p-type polycrystalline silicon sphere (p-type semiconductor layer) 11 having good crystallinity, and silane containing phosphine is formed on the surface. An n-type polycrystalline silicon layer (n-type semiconductor layer) 12 is formed by a CVD method using the above mixed gas. Here, in the CVD process, a thin film is formed by supplying and discharging a gas heated to a desired reaction temperature while carrying a silicon sphere in a thin tube.
[0018]
In this step, the p-type polycrystalline silicon grains are spheroidized while being heated and dropped in vacuum to form a p-type polycrystalline silicon sphere (p-type semiconductor layer) 11 and a desired gas in the course of dropping. It is also possible to form an n-type polycrystalline silicon layer (n-type semiconductor layer) 12 by contacting them.
[0019]
Next, two examples of the first manufacturing method and the second manufacturing method will be described as a solar cell manufacturing method using the spherical cell 10 described above, and will be described with reference to FIGS.
[0020]
(First manufacturing method)
FIG. 3 is a schematic cross-sectional view illustrating steps (a) to (d) in the first manufacturing method.
FIG. 4 is a schematic cross-sectional view illustrating steps (e) to (g) in the first manufacturing method.
First, as shown in FIG. 3A, a transparent substrate 21 having a transparent conductive layer 13 (for example, ITO) formed on a transparent member 14 (for example, glass) is prepared.
[0021]
Next, as shown in FIG. 3B, the spherical cell 10 is placed on the transparent conductive layer 13 and bonded thereto by pouring, for example, ITO or the like in a state where the spherical cell 10 is pressed by a press device or the like. Positioning at this time is not particularly required, and as an arrangement method thereof, for example, an aggregation type arrangement method in which spherical cells 10 are arranged so as to contact each other without a gap, a lattice-like arrangement method having a certain gap, or It can be arranged in an arbitrary shape by an arrangement method such as a staggered arrangement method.
[0022]
Next, as shown in FIG. 3C, a transparent resin having an electrical insulation property (for example, a sensitizer such as rhodamine) is poured into the spherical cell 10 until a part of the spherical cell 10 is exposed from the liquid surface and cured. The transparent insulating layer 15 is formed.
[0023]
Next, as shown in FIG. 3D, only the n-type semiconductor layer 12 of the spherical cell 10 exposed from the transparent insulating layer 15 is etched to expose the internal p-type semiconductor layer 11.
[0024]
Next, as shown in FIG. 4E, an insulating member (for example, epoxy resin) is applied (coated) on the transparent insulating layer 15 and the spherical cell 10 to form the insulating layer 16. At this time, coating is performed so that a part of the center of the p-type semiconductor layer 11 exposed in the step in FIG.
[0025]
Next, as shown in FIG. 4F, the exposed surface of the p-type semiconductor layer 11 on the transparent insulating layer 15 (the surface of the p-type semiconductor layer 11 and the insulating layer 16 ) is formed of a conductive metal film. It coats (for example, sputtering aluminum etc.) and makes this the conductive layer 17 (inner electrode of a solar cell).
[0026]
Finally, as shown in FIG. 4G, the solar cell according to the present embodiment is formed by reversing the upper and lower sides (assuming that sunlight is irradiated from the upper surface).
[0027]
(Second manufacturing method)
FIG. 5 is a schematic cross-sectional view illustrating steps (a) to (d) in the second manufacturing method.
FIG. 6 is a schematic cross-sectional view illustrating steps (e) to (g) in the second manufacturing method.
First, as shown in FIG. 5A, the upper and lower flat transparent substrates 21 each having a flat transparent conductive layer 13 (for example, ITO) formed on a flat transparent member 14 (for example, glass). Prepare.
[0028]
Next, as shown in FIG. 5B, the spherical cell 10 is placed on the transparent conductive layer 13 and is adhered by pouring, for example, ITO or the like in a state where the spherical cell 10 is pressed by a press device or the like. Positioning at this time is not particularly required, and as an arrangement method thereof, for example, an aggregation type arrangement method in which spherical cells 10 are arranged so as to contact each other without a gap, a lattice-like arrangement method having a certain gap, or It can be arranged in an arbitrary shape by an arrangement method such as a staggered arrangement method.
[0029]
Next, as shown in FIG. 5C, a transparent insulating layer 15 having electrical insulation (for example, a sensitizing material such as rhodamine) is poured and cured so that the entire part of the spherical cell 10 is buried. .
[0030]
Next, as shown in FIG. 5D, the surface of the transparent insulating layer 15 and the spherical cell 10 are ground by grinding or the like so that the p-type semiconductor layer 11 inside the spherical cell 10 is exposed from the transparent insulating layer 15. Grind flat and remove.
[0031]
Next, as shown in FIG. 6 (e), a sheet-like insulating member having a through-hole H on its surface is attached to the surface of the transparent insulating layer 15 and the spherical cell 10, and this is attached to the insulating layer 16 with a hole. To do. This through hole H is previously opened so as to communicate only with the p-type semiconductor layer 11 exposed on the surface of the spherical cell 10 by the above grinding.
[0032]
Next, as shown in FIG. 6F, for example, silver paste is squeezed so that the surface of the insulating layer 16 with holes is covered with the conductive member and fills the through holes H. After the treatment, it is embedded in the through hole, heated to 150 ° C. to 200 ° C., and subjected to a curing (curing) treatment for about 1 hour. This is defined as a conductive layer 17 (inner electrode of solar cell). Here, as shown, the conductive layer 17 has a flat outer surface.
[0033]
Finally, as shown in FIG. 6G, the solar cell according to the present embodiment is formed by reversing the upper and lower sides (assuming that sunlight is irradiated from the upper surface).
[0034]
In the above-described embodiment, the first conductivity type is p-type and the second conductivity type is n-type. However, the first conductivity type is n-type and the second conductivity type is p-type. It can be done.
Moreover, although the spherical cell which uses a p-type polycrystal as a spherical substrate was used, you may use a p-type single crystal or p-type amorphous silicon.
Moreover, the conductive layer 17 (inner electrode of the solar cell) can be used as a light receiving surface on both the front and back surfaces of the solar cell by forming it with a transparent conductive film such as ITO.
[0035]
【The invention's effect】
As described above in detail, according to the solar cell manufacturing method and solar cell of the present invention, it is not necessary to accurately position the spherical cell, and even if the spherical shape and diameter of the spherical cell are not constant spheres. well, even if there are variations in the shape or diameter can be manufactured.
Moreover, it can arrange in arbitrary shapes by arrangement methods, such as an aggregation type arrangement method, a lattice arrangement method, and a staggered arrangement method, and free design is possible.
In addition, since the conductive layer can be formed of an aluminum thin film (since the aluminum thin film has good reflection efficiency), the reflected sunlight can be taken into the spherical cell, so that the sunlight can be used efficiently. .
Alternatively, the conductive layer can be formed of a transparent conductive film, and in this case, both the front and back surfaces of the solar cell can be used as the light receiving surface, so that more efficient use of sunlight can be achieved. Is.
Alternatively, the insulating layer can be manufactured by attaching an insulating member having a through hole. In this case, a process such as a melting / curing treatment of the insulating resin is not required, and the manufacturing is further facilitated.
With these effects, it is possible to provide a solar cell with excellent light receiving efficiency by a low-cost and simple method for manufacturing a solar cell.
[Brief description of the drawings]
FIG. 1 is a perspective view of a main part of a solar cell according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view illustrating a solar cell according to an embodiment of the present invention.
FIG. 3 is a schematic cross-sectional view of steps (a) to (d) in the first method for manufacturing a solar cell according to the embodiment of the present invention.
FIG. 4 is a schematic cross-sectional view of steps (e) to (g) in the first method for manufacturing a solar cell according to the embodiment of the present invention.
FIG. 5 is a schematic cross-sectional view of steps (a) to (d) in the second method for manufacturing a solar cell according to the embodiment of the present invention.
FIG. 6 is a schematic cross-sectional view of steps (e) to (g) in the second method for manufacturing a solar cell according to the embodiment of the present invention.
FIG. 7 is a schematic cross-sectional view illustrating a conventional solar cell.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Spherical cell 11 1st conductivity type (p-type) semiconductor layer 12 2nd conductivity type (n-type) semiconductor layer 13 Transparent conductive layer 14 Transparent member 15 Transparent insulating layer 16 Insulating layer 17 Conductive layer 20 Solar cell substrate 21 Transparent substrate

Claims (4)

In a method for manufacturing a solar cell using a spherical cell formed by forming a second conductive type semiconductor layer on a spherical substrate surface having a first conductive type semiconductor layer,
Forming a transparent conductive layer on a flat transparent member to form an upper and lower flat transparent substrate;
On the transparent substrate, the step of placing the spherical cell and bonding the transparent substrate and the spherical cell with a transparent conductive adhesive layer in a state where the spherical cell is pressed.
Melting a transparent resin having electrical insulation, pouring until a part of the spherical cell is exposed from the liquid surface, curing, and forming a transparent insulating layer;
Etching only the second conductive semiconductor layer of the spherical cell exposed from the transparent insulating layer to expose the first conductive semiconductor layer inside;
On the transparent insulating layer and the spherical cell, as part of the central of the exposed first conductive type semiconductor layer of the spheres cell remains exposed, by applying an insulating member, an insulating layer And a process of
Forming a transparent conductive layer on the exposed surface of the first conductive semiconductor layer on the transparent insulating layer. In a method for manufacturing a solar cell using a spherical cell formed by forming a second conductive type semiconductor layer on a spherical substrate surface having a first conductive type semiconductor layer,
Forming a transparent conductive layer on a flat transparent member to form an upper and lower flat transparent substrate;
On the transparent substrate, the step of placing the spherical cell and bonding the transparent substrate and the spherical cell with a transparent conductive adhesive layer in a state where the spherical cell is pressed.
Melting a transparent resin having electrical insulating properties, pouring so as to fill the entire part of the spherical cell, curing, and forming a transparent insulating layer;
As the first conductivity type semiconductor layer inside the sphere cells from said transparent insulating layer is exposed, and wherein the step of grinding the surface of the transparent insulating layer and sphere cell removal,
Attaching an insulating member having a through hole communicating only with the first conductive semiconductor layer to the surface of the transparent insulating layer and the spherical cell to form an insulating layer with a hole ;
The covered with transparent conductive member the surface of the insulating member, and a method for manufacturing a solar cell characterized by comprising a step of the is filled with a transparent conductive member in the through hole, to form a transparent conductive layer. A spherical cell having a first conductive type semiconductor layer on the inside and a second conductive type semiconductor layer on the surface is a flat lower transparent conductive layer, an insulating layer, a transparent insulating layer, a flat upper transparent conductive layer, a flat surface in order from the lower layer. transparent member is formed so as to fill the upper and lower surfaces planar substrate that is laminated, flat above the first conductive type semiconductor layer of the spherical cells and the second conductive semiconductor layer is partially ablated said substrate the inner electrode is formed by being electrically connected to the lower transparent conductive layer, wherein said second conductive type semiconductor layer of the spheres cell is flat the upper transparent conductive layer electrically connected to said substrate solar cells are the outer electrode is formed by the insulating layer and the transparent insulating layer, and the lower transparent conductive layer and the upper transparent conductive layer is characterized by comprising electrically insulated by. The insulating layer has a through hole communicating only with the first conductive semiconductor layer of the spherical cell, and the lower transparent conductive layer is laminated on the outer surface of the insulating layer so as to fill the through hole. The solar cell according to claim 3, wherein is a flat inner electrode.

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