ES2365155T3 - PROVISION OF SPHERICAL SOLAR CELLS AND THEIR MANUFACTURING PROCEDURE. - Google Patents

Abstract

Method of producing a photovoltaic device comprising: a plurality of substantially spherical photovoltaic elements (10, 20), each comprising: a first substantially spherical semiconductor (1); a second semiconductor layer (2) that covers the surface of the first semiconductor (1); a conductive antireflection coating (9) covering the surface of the second semiconductor layer (2), said antireflection coating (9) and said second semiconductor layer (2) having a common opening through which a part is exposed of the first semiconductor (1); and an electrode (5, 62, 67, 79, 97) formed on the exposed part (4, 14, 96) of the first semiconductor; a support (15, 25, 35) having a plurality of adjacent recesses (16, 26, 36) to cover said photovoltaic elements (10, 20) one by one on a front face thereof, each of the recesses ( 16, 26, 36) an inner face that functions as a reflecting mirror and an opening (17, 27, 37) in a lower part thereof, the opening (17, 27, 37) being smaller than each of said photovoltaic elements (10, 20), said support (15, 25, 35) serving as a second conductor layer that is electrically connected with the second semiconductor layers (2) of the respective photovoltaic elements (10, 20) arranged in said recesses ( 16, 26, 36), with said anti-reflection coating (9) interposed between said second semiconductor layers (2) and said support (15, 25, 35), each of said photovoltaic elements (10, 20) being fixed to each one of said recesses (16, 26, 36) with a conductive adhesive (13, 51), so that the coating or antireflection (9) thereof is in contact with an edge of said opening (17, 27, 37) of the recess (16, 26, 36) and that the exposed part (4, 14, 96) of the first semiconductor (1) protrudes through a rear face of the support (15, 25, 35); and an electrical insulating layer (38, 71, 91) and a first conductor layer (32, 70, 92) which are provided on the rear face of the support (15, 25, 35), so that said insulating layer electrical (38, 71, 91) isolate the support (15, 25, 35) of the first conductor layer (32, 70, 92), said electrical insulating layer (38, 71, 91) having a plurality of through holes (60, 68, 73, 75, 77, 93, 95), said first conductor layer (32, 70, 92) being electrically connected to said electrodes (5, 62, 67, 79, 97) of said photovoltaic elements ( 10, 20) through the through holes (60, 68, 73, 75, 77, 93, 95) or said electrical insulating layer (38, 71, 91), said process comprising the following steps: (a) providing a plurality of substantially spherical photovoltaic elements A1, each comprising a first substantially spherical semiconductor (1) and a second semiconductor layer (2) that covers the entire surface of the first semiconductor (1), and forms a conductive anti-reflection coating (9) on the surface of each of said second semiconductor layers (2); (b) forming an opening in the second semiconductor layer (2) of each of said photovoltaic elements A1 to expose a part (4, 14, 96) of the first semiconductor (1), to prepare photovoltaic elements A2, in which a part of said anti-reflection coating (9) is removed together with the second semiconductor layer (2) to form said opening; (c) forming an electrode (5, 62, 67, 79, 97) on the exposed part (4, 14, 96) of the first semiconductor (1) of each of said photovoltaic elements A2, to prepare photovoltaic elements A3; (d) provide said support (15, 25, 35); (e) apply a conductive adhesive (13, 51) to a periphery of each of the openings (17, 27, 37) of said support (15, 25, 35); (f) arranging said photovoltaic elements A1, A2 or A3 in the recesses (16, 26, 36) of said support (15, 25, 35) so that the second semiconductor layers (2) are in contact with the edges of the openings (17, 27, 37) of said support, and connecting said second semiconductor layers (2) to said support (15, 25, 35) electrically and physically with said conductive adhesive (13, 51); (g) forming an electrical insulating layer (38, 71, 91) on the rear face of said support (15, 25, 35); (h) forming through holes (60, 68, 73, 75, 77, 93, 95) in said electrical insulating layer (38, 71, 91), said through holes serving as conductive paths for interconnecting the electrodes (5, 62, 67, 79, 97) of said photovoltaic elements A3; and (i) forming a first conductor layer (32, 70, 92) on said electrical insulator layer (38, 71, 91), said first conductor layer electrically interconnecting the electrodes (5, 62, 67, 79, 97 ) which are exposed within said through holes (60, 68, 73, 75, 77, 93, 95), wherein said stage (e) is performed before said stage (f), and said stage (f) is performed before said stage (g).

Description

Field of the Invention

The present invention relates to a process for producing a photovoltaic device that includes spherical photovoltaic elements and the photovoltaic device.

Background of the invention

Photovoltaic devices have received attention as a source of clean energy. There are two types of representative photovoltaic devices: those that use an element made from a crystalline silicon semiconductor wafer; and those that use a semiconductor layer made from amorphous silicon. The first requires complicated steps to produce a monocrystalline ingot and process the monocrystalline ingot to obtain semiconductor wafers. In addition, its production cost is high, since the utilization rate of the expensive raw silicon material is low due to the crystal residue produced in the cutting stage or the like. In the latter, when the amorphous structure, in which hydrogen is combined with the silicon free bond, is exposed to light, hydrogen is released and a structural change tends to occur. Therefore, the last device presents the problem that photovoltaic efficiency is gradually reduced due to exposure to light.

To provide a photovoltaic device that is free from such degradation of features, cheap, and expected to provide high output power, spherical solar cells using a spherical photovoltaic element consisting of a p-type semiconductor have been examined spherical (first semiconductor) and a n-type semiconductor layer (second semiconductor layer) formed on the surface of the spherical p-type semiconductor. An example of this type is a solar arrangement as proposed in US Patent No. 4,581,103, in which spherical silicon (Si) elements are embedded in the openings of a flat aluminum sheet (Al), its semiconductor layers Type n are subjected to chemical attack from the rear face of the aluminum sheet to expose the inner p-type semiconductors, and the exposed p-type semiconductors are connected to another aluminum sheet.

This proposal uses small elements with a diameter of approximately 1 mm, thereby decreasing the average thickness of the entire photovoltaic section and reducing the amount of Si of high purity. However, since this spherical solar cell is of the type that does not use reflected light, its output power per element is low. Therefore, in order to improve the efficiency of conversion by module light receiving surface, it is necessary to arrange a large number of elements densely so that they are close to each other. Therefore, the process for connecting the elements to the aluminum foil is complicated and, in addition, a large number of elements are necessary. As a result, a large reduction in cost is not possible.

Also, to join the Si semiconductors to the conductive layer of aluminum foil and obtain a good electrical connection between them, the above proposal includes the step of applying a heat treatment at 500 to 577 ° C to form an alloy layer of aluminum and Si at the junction between them. However, such a thermal treatment causes a short-circuit phenomenon since the second semiconductor layer is a thin layer with a thickness of 0.5 µm or less and the conductive layer crosses the thin second semiconductor layer after the heat treatment . Therefore, there are disadvantages of major deterioration in open circuit voltage, fill factor, and the like.

To solve these problems, a solar cell has been proposed that is composed of a support with a large number of recesses and spherical photovoltaic elements with a diameter of approximately 1 mm arranged in the recesses, in which the inner faces of the recesses are used as reflective mirrors (for example, Japanese patent publication open to the public No. 2002-50780, US 2002/0096206 A1, and US 2004/0016456 A1). A solar cell of this type is called a spherical solar cell of the micro concentrator type or of a low concentrator type. A first advantage of this configuration is a reduction in the amount of elementary materials, particularly the expensive Si. A second advantage is the efficient use of light; Due to the action of the reflective mirror, light that is 4 to 6 times the light directly incident on the element can be allowed into the element.

The proposal described above by the present inventors (US 2004/0016456 A1) is described below, as a representative conventional procedure for producing photovoltaic devices of this type. A photovoltaic element comprises a first spherical semiconductor and a second semiconductor layer that covers the surface thereof, and a part of the first semiconductor is exposed from the second semiconductor layer. An electrode is previously formed on the exposed part of the first semiconductor and the second semiconductor layer. A support has a plurality of recesses to cover such elements and comprises a second conductor layer that is to be electrically connected to the second semiconductor layers and an electrical insulator layer formed on the rear face of the second conductor layer. On the rear face of the electrical insulating layer a first conductor layer is formed which electrically interconnects the electrodes of the first semiconductors.

According to a configuration of this type, before arranging the elements in the support, the electrode is formed which requires a high temperature heat treatment. Therefore, there is an advantage that the electrodes and the conductive layer can be connected at a relatively low temperature after arranging the elements in the holder. However, since the electrode for the second semiconductor layer is formed on a curved surface close to the opening of the second semiconductor layer, such an electrode formation requires precise positioning and a technique to form a fine shape. being therefore unsuitable for mass production.

In addition, this support has a two-layer structure consisting of the second conductor layer with the recesses to cover the elements and the electrical insulating layer. A support of this type can be produced, for example, by laminating in solidarity a second conductor layer, which is obtained by working a metal sheet to form a plurality of recesses, each recess having an opening in the bottom, and a sheet of electrical insulator with through holes corresponding to the openings. However, at present, in the process of integrating these two sheets by adhesion or bonded by thermocompression, the electrical insulating sheet made from resin can be deformed, thereby causing changes in the distance of separation of dimensions, and shape of the through holes and therefore a displacement. Therefore, it is difficult to produce such a support with good precision. The three-layer support as disclosed, for example, in US 2002/0096206 A1 also presents the same problem as the two-layer support mentioned above.

In addition, in spherical solar cells, it is extremely important to mount all of the large number of very small spherical elements in predetermined positions within small recesses accurately and quickly if the positioning of the elements is inaccurate or a displacement occurs during the process In the production or operation of the spherical solar cell, the second conductor layer comes into contact with the exposed part or electrode of the first semiconductor to cause a short circuit, or an electrical connection between the semiconductor and the conductive layer cannot be formed. In case of separation of the elements, the output power of the photovoltaic device is reduced.

To solve these problems, for example, document US 2004/0016456 A1 discloses a method for positioning elements, with a conductive paste applied to the electrodes of its second semiconductors, within the recesses of the support, and then heating the elements for fix them to the support. However, this procedure presents the following problems. For example, it is difficult to apply the conductive paste to the tiny electrodes at high speed. Also, in the process of positioning the elements in the support, the conductive paste applied to the elements adheres to the reflecting mirrors of the recesses, thereby reducing the photovoltaic efficiency.

Brief summary of the invention

The present invention addresses the aforementioned problems associated with the spherical solar cell which is composed of a support with a large number of spherical recesses and photovoltaic elements arranged in the respective recesses. There is a need for a process to effectively produce a photovoltaic device with high quality and high reliability, fixing the elements to photovoltaic elements welded into the holes. Each of the photovoltaic elements includes a coating that prevents reflection.

EP-A-1,213,772 discloses a photovoltaic apparatus that has recesses with reflective interior walls that function as mirrors.

Brief summary of the invention

The present invention addresses the aforementioned problems associated with the spherical solar cell which is composed of a support with a large number of spherical recesses and photovoltaic elements arranged in the respective recesses. There is a need for a process to efficiently produce a photovoltaic device with high quality and high reliability, by fixing the elements in predetermined positions within the respective recesses reliably and electrically connecting the semiconductors of the elements to the conductive layer with a low resistance. There is also a need for a photovoltaic device of this type with high quality and high reliability.

The present invention provides a method of producing a photovoltaic device according to claim 1.

In a first preferred embodiment of the production process of the present invention, steps (a) and (d) are performed, and then steps (e), (f), (b), (g), (h), (c), e (i) in this order. In a second preferred embodiment, steps (a) and (d) are performed, and then steps (e), (f), (b), (c), (g), (h), and (i) in this order. In addition, in a third preferred embodiment, steps (a) and (d) are performed, and then steps (e), (f), (g), (h), (b), (c) are performed , e (i) in this order.

In the first to third embodiments, first, step (a) is performed to prepare a plurality of photovoltaic elements A1, while step (d) is performed to prepare a support that serves as a second conductor layer . Subsequently, step (e) is performed to apply a conductive adhesive to the periphery of each of the support openings. In the next step (f), each of the photovoltaic elements A1 is arranged in each recess of the support so that the second semiconductor layer thereof is in contact with the edge of the opening, whereby the layer The second semiconductor adheres to the edge of the opening with the conductive adhesive, and in addition, the support is heated to solidify the conductive adhesive. These steps produce a structure B1 in which the photovoltaic elements A1 are fixed in the predetermined positions of the support so that their second semiconductor layers are electrically connected to the second conductor layer.

In the first embodiment, after steps (a), (d), (e), and (f), step (b) is performed. That is, at least a part of the second semiconductor layer of each photovoltaic element A1 is removed on the rear face of the support of the structure B1 to expose the first semiconductor. As a result, photovoltaic elements A1 become photovoltaic elements A2. Subsequently, step (g) is performed to form an electrical insulator layer on the back face of the support, and then step (h) is made to form through holes in the electrical insulator layer so that it is exposed at least a part of the exposed part of the first semiconductor of each photovoltaic element A2. Next, step (c) is performed to form an electrode on the exposed surface of the first semiconductor within each through hole. As a result, photovoltaic elements A2 become photovoltaic elements A3. In the last stage (i), a first conductor layer is formed. The first conductor layer electrically interconnects the electrodes of the photovoltaic elements A3 that are exposed within the through holes of the electrical insulating layer, with the through holes serving as conductive paths.

In the second embodiment, in the same way as in the first embodiment, after steps (a), (d), (e), and (f), step (b) is performed to expose at least a part of the first semiconductor on the rear face of the support of the structure B1. As a result, photovoltaic elements A1 become photovoltaic elements A2. Next, step (c) is performed to form an electrode on the exposed surface of the first semiconductor. As a result, photovoltaic elements A2 become photovoltaic elements A3. Subsequently, step (g) is performed to form an electrical insulator layer on the back face of the support, and then step (h) is made to form through holes in the electrical insulator layer so that the electrodes of the the photovoltaic elements A3. In the last stage (i), a first conductor layer is formed in the same manner as in the first embodiment.

In the third embodiment, after steps (a), (d), (e), and (f), step (g) is performed to form an electrical insulating layer on the back face of the support of the structure B1, and then the stage is performed

(h) to form through holes in the electrical insulator layer so that a part of the second semiconductor layer of each photovoltaic element A1 is exposed. Subsequently, step (b) is performed to remove the part of the second semiconductor layer exposed within each through hole of the electrical insulator layer so that the first semiconductor is exposed. As a result, photovoltaic elements A1 become photovoltaic elements A2. Then step (c) is performed to form an electrode on the exposed surface of the first semiconductor of each photovoltaic element A2. As a result, photovoltaic elements A2 become photovoltaic elements A3. In the last stage (i), a first conductor layer is formed in the same manner as in the first embodiment.

In a fourth preferred embodiment of the production process of the present invention, steps (a), (b), (c), and (d) are performed, and then steps (e), (f) are performed. , (g), (h), e (i) in this order. In the fourth embodiment, first, stage (a) is performed to prepare photovoltaic elements A1, and then stage (b) is performed to remove a part of the second semiconductor layer of each photovoltaic element A1 to expose a part of the first semiconductor. As a result, A2 photovoltaic elements are obtained. Subsequently, step (c) is performed to form an electrode on the exposed surfaces of the first semiconductors of the photovoltaic elements A2, to prepare photovoltaic elements A3. Meanwhile, step (d) is performed to prepare a support in the same manner as in embodiment 1. Subsequently, step (e) is performed to apply a conductive adhesive to the periphery of each support opening. Then, in step (f), each of the photovoltaic elements A3 is disposed in each recess of the support so that the second semiconductor layer thereof is in contact with the edge of the opening, and the support is heated to solidify the conductive adhesive. These steps produce a structure B2 in which the photovoltaic elements A3 with the electrodes are fixed to the predetermined positions of the support so that their second semiconductor layers are electrically connected to the second conductor layer.

Then, step (g) is performed to form an electrical insulator layer on the back face of the support of structure B2, and then step (h) is made to form through holes in the electrical insulator layer so that they are exposed the electrodes of the photovoltaic elements A3. In the last stage (i), a first conductor layer is formed in the same manner as in the first embodiment.

In a fifth preferred embodiment of the production process of the present invention, steps (a), (b), and (d) are performed, and then steps (e), (f), (g) are performed , (h), (c), e (i) in this order. In the fifth embodiment, first, step (a) is carried out to prepare photovoltaic elements A1. Next, step (b) is performed to remove a part of the second semiconductor layer to expose a part of the first semiconductor. As a result, A2 photovoltaic elements are obtained. Meanwhile, step (d) is performed to prepare a support that serves as a second conductor layer. Subsequently, step (e) is performed to apply a conductive adhesive to the periphery of each support opening. In the next step (f), each of the photovoltaic elements A2 is disposed in each recess of the support so that the second semiconductor layer is in contact with the edge of the opening, and the support is heated to solidify the conductive adhesive . These steps produce a structure B3 in which the photovoltaic elements A2, each having the exposed part of the first semiconductor, are fixed to the predetermined positions of the support so that their second semiconductor layers are electrically connected to the second conductor layer .

Next, step (g) is performed to form an electrical insulator layer on the back face of the support of structure B3, and then step (h) is made to form through holes in the electrical insulator layer so that The first semiconductor of each photovoltaic element A2 is exposed within each through hole. Next, step (c) is performed to form an electrode on the exposed surface of the first semiconductor within the through hole of the electrical insulating layer. As a result, photovoltaic elements A2 become photovoltaic elements A3. In the last stage (i), a first conductor layer is formed in the same manner as in the first embodiment.

It is preferred that the photovoltaic elements of the present invention consist mainly of silicon.

The antireflection coating preferably comprises tin oxide doped with at least one of fluorine and antimony and preferably has a thickness of 50 to 100 nm.

Step (e) preferably includes the following stages:

apply the conductive adhesive on pin tips that are slightly larger than the support openings; Y

transfer the conductive adhesive applied to the tips to the peripheries of the openings, inserting the tips into the recesses of the support from the front face of the support and putting the tips in contact with the peripheries of the openings so that the centers of the tips and the openings line up.

Step (e) preferably includes the following stages:

placing a metal mask on the rear face of the support, the metal mask presenting a plurality of groups of openings corresponding to the openings of the support, each group of openings consisting of a plurality of openings that are arranged along an opening edge of each opening, each opening being shaped so that it covers an area that extends from an outer part of the opening edge of the opening to an inner part thereof; and

print the conductive adhesive on the support through the openings of the metal mask, so that the conductive adhesive is applied to the support in a plurality of locations along the opening edge of each of the openings so that it covers a area that extends from a periphery of each opening on the rear face of the support to a periphery of the opening on the front face thereof.

Step (b) preferably includes removing a part of the second semiconductor layer of each of the photovoltaic elements A1 by chemical attack, to form the opening. Step (b) preferably includes, before the chemical attack stage, the stage of previously removing the part of the second semiconductor layer that is to be subjected to chemical attack by brushing or sandblasting.

In the fourth embodiment, step (b) preferably includes the step of cutting a part of each of the photovoltaic elements A1 so that the opening of the second semiconductor layer thereof is substantially flush with the exposed part of the First semiconductor

Step (c) preferably includes the following stages:

apply a conductive paste to the exposed part of the first semiconductor of each of the photovoltaic elements A2; Y

apply a heat treatment to the conductive paste applied by laser irradiation, to form the electrode.

In the fourth embodiment, step (b) preferably includes the steps of: providing a support element having a plurality of recesses in a predetermined pattern for coating the photovoltaic elements A1 at a predetermined depth;

arrange the photovoltaic elements A1 in the recesses of the support element;

apply a molten wax to the support element and cool it, to fix the photovoltaic elements A1 to the recesses of the support element with the solidified wax; Y

pressing a rotary grinder on the photovoltaic elements A1 fixed to the support element to rectify the surfaces of the photovoltaic elements A1, to form the exposed parts of the first semiconductors, and step (c) preferably includes the steps of:

apply a conductive paste to the exposed parts of the first semiconductors; Y

heating the support element at a temperature of 400 to 800 ° C, to remove the wax and form the electrodes on the exposed parts of the first semiconductors.

In the fourth embodiment, each of the photovoltaic elements A3 is preferably configured so that the electrode or its surroundings is more magnetic than other parts, and step (f) preferably includes the stage of applying a magnetic field to the photovoltaic elements A3 in a predetermined direction, to align the electrodes or their vicinity in a predetermined orientation.

The step (g) preferably includes the step of joining a semi-cured electrical insulating layer, comprising an insulating sheet composed mainly of a thermosetting resin, to the back face of the pressure support. Step (i) preferably includes the steps of:

bond a conductive metal foil to the electrical semi-cured pressure insulating layer; Y

arrange the semi-cured electrical insulating layer by means of a heat treatment, to fix the conductive metal sheet to the electrical insulating layer.

Step (i) preferably includes the step of applying a conductive paste to the electrical insulating layer so that it interconnects the electrodes of the photovoltaic elements A3 that are exposed within the through holes of the electrical insulating layer and heating it for solidification. , to form the first conductor layer.

Step (i) preferably includes the following stages:

fill the through holes of the electrical insulating layer with a conductive paste so that they come into contact with the electrodes of the photovoltaic elements A3;

bond a conductive metal sheet to the electrical insulating layer; Y

heat and solidify the conductive paste, to electrically connect the conductive paste to the conductive metal sheet.

In the second and fourth embodiments, steps (g) to (i) preferably include the steps of:

joining an electrical insulating layer and a conductive metal sheet to the rear face of the support so that the electrical insulating layer separates the conductive metal sheet from the support;

form through holes in the electrical insulating layer and the conductive metal sheet glued to the support to expose the electrodes of the photovoltaic elements A3 within the through holes; Y

Fill the through holes to electrically connect the electrodes to the conductive metal sheet with a conductive paste to form the first conductor layer.

In the second and fourth embodiments, the step of joining the electrical insulating layer and the conductive metal sheet to the rear face of the support preferably includes the step of joining a composite sheet, which includes a conductive metal sheet and a layer of electrical insulation laminated to one side of the conductive metal sheet, to the rear face of the support so that the electrical insulation layer is faced with the support.

In the second and fourth embodiments, the step of joining the composite sheet comprises the following steps:

apply an electrically insulating adhesive to the back face of the support, to form a layer of adhesive; and bonding the electrical insulating layer of the composite sheet to the adhesive layer of the support.

In claim 27 a photovoltaic device according to the present invention is disclosed.

While the novel features of the invention are set forth in particular in the appended claims, the invention, both in organization and in content, will be better understood and appreciated, together with other objectives and characteristics thereof, from the following detailed description. Taken together with the drawings.

Brief description of the various views of the drawings

Figure 1 is a longitudinal sectional view of a photovoltaic element A1 prepared in step (a);

Figure 2 is a longitudinal sectional view of a photovoltaic element A1 with an anti-reflection coating on the surface, which is prepared in step (a) of the present invention;

Figure 3 is a plan view of a support in a first mode, which is prepared in step (d) of the present invention;

Figure 4 is a cross-sectional view of the support of Figure 3 taken along line 4-4 thereof;

Figure 5 is a longitudinal sectional view of a support in a second mode, which is prepared in step (d) of the present invention;

Figure 6 is a longitudinal sectional view of a support in a third mode, which is prepared in step (d) of the present invention;

Figure 7 are longitudinal sectional views showing the step of applying a conductive adhesive on the support in step (e) of the present invention;

Figure 8 is a plan view of a metal screen used in another application method in the previous stage of the present invention;

Figure 9 is a longitudinal sectional view of the support with the conductive adhesive applied thereto with the metal screen of Figure 8;

Figure 10 are longitudinal sectional views showing the step of arranging photovoltaic elements A1 in the support with the conductive adhesive applied thereto in step (f) of embodiments 1 to 3 of the present invention;

Figure 11 is a longitudinal sectional view of the support with the photovoltaic element A1 disposed therein, which is obtained by the previous step (f);

Figure 12 is a longitudinal sectional view of a structure that includes a photovoltaic element A2, which is obtained by conversion from photovoltaic element A1 of Figure 11 by step (b) of embodiments 1 and 2;

Figure 13 are views in longitudinal section showing the steps of forming an electrical insulating layer on the rear face of the structure of Figure 12 and forming a through hole in the interior thereof that serves as a conductive path in the stages (g) and (h) of embodiment 1;

Figure 14 are views in longitudinal section showing the step of forming an electrode on the surface of the first semiconductor of the structure of Figure 13 in step (c) of the previous embodiment;

Fig. 15 are views in longitudinal section showing the step of forming a first conductor layer on the electrical insulating layer of the structure of Fig. 14 by a first method of step (i) of the previous embodiment;

Figure 16 is a longitudinal sectional view of a photovoltaic device with a first conductor layer formed by a second method of the previous stage;

Figure 17 are views in longitudinal section showing the stage of forming a first conductor layer by a third method of the previous stage;

Figure 18 is a plan view showing an application pattern of the conductive paste applied to the electrical insulating layer in the stage of Figure 17;

Figure 19 are longitudinal sectional views showing the step of forming an electrode on the photovoltaic element A2 of the structure of Figure 11 in step (c) of embodiment 2 of the present invention, by means of which the element photovoltaic A2 becomes a photovoltaic element A3;

Figure 20 are longitudinal sectional views showing the steps of forming an electrical insulating layer on the rear face of the structure obtained by the stage of Figure 19 and forming a first conductor layer thereon, in the stages (g ), (h), e (i) of embodiment 2 of the present invention;

Figure 21A and 21B are longitudinal sectional views showing another method of forming an electrical insulator layer and a first conductor layer in the previous stages;

Figure 22 are views in longitudinal section showing the stages from the stage of converting the photovoltaic element A1 of a structure B1 into a photovoltaic element A3 to the stage of forming a first conductor layer in the stages (g), (h ), (b), (c), e (i) of embodiment 3 of the present invention;

Figure 23 is a longitudinal sectional view of a photovoltaic element A2 obtained by step (b) of embodiment 4 of the present invention;

Figure 24 is a bottom view of the photovoltaic element A2 of Figure 23;

Figure 25 is a longitudinal sectional view of another photovoltaic element A2 obtained by the previous stage;

Figure 26 is a longitudinal sectional view of a photovoltaic element A3 obtained by step (c) of embodiment 4 of the present invention;

Figure 27 are longitudinal sectional views showing other example photovoltaic elements A3 obtained by the previous stage;

Fig. 28A and 28B are longitudinal sectional views showing the step of arranging the photovoltaic elements A3 in the support with the conductive adhesive applied thereto in the step (f) of the embodiment 4 of the present invention;

Fig. 29 are views in longitudinal section showing the first stage for arranging the photovoltaic elements A3 in the support with the conductive adhesive applied thereto by another method of the previous stage;

Figure 30 are views in longitudinal section showing the intermediate stage for the previous stage;

Figure 31 are views in longitudinal section showing the last stage for the previous stage;

Figure 32 are longitudinal sectional views showing the steps of forming an electrical insulating layer and a first conductor layer on the rear face of a structure B2 in stages (g), (h), e (i) of the embodiment 4 of the present invention;

Figure 33 are longitudinal sectional views showing the steps of forming an electrical insulator layer and a first conductor layer according to another process of steps (g), (h), e (i) of embodiment 4 of the present invention;

Figure 34 are longitudinal sectional views showing the stages from the stage of arranging the photovoltaic element A2 in the support in stage (f) to the stage of forming a first conductor layer in stage (i) of embodiment 5 of the present invention; Y

Figure 35 is a longitudinal sectional view showing a photovoltaic device according to the present invention.

Detailed description of the invention

Figure 1 illustrates an element in which a semiconductor layer of type not a semiconductor layer of type p is formed on the surface of a first semiconductor 1 as a layer of second semiconductor 2. Figure 2 illustrates an additional element presenting a conductive anti-reflection coating 9 on the second semiconductor layer 2. The elements can be exchanged as illustrated in Figures 1 and 2 as the element A1.

The reader should note that, although much of the following description is provided with reference to the element of Figure 1, the photovoltaic device produced using the element of Figure 1 is outside the scope of the present invention.

The reader must mentally replace the element of Figure 1 with the element of Figure 2 so that it conceives a production process that produces a photovoltaic device that is according to the present invention.

The present invention has been particularly completed by treating the problems indicated above associated with the production process according to the invention of the present inventors as disclosed in US 2004/0016456 A1. The present invention has made it possible to effectively produce a spherical solar cell with high quality and high reliability.

A first characteristic of the production process according to the present invention is that before mounting the photovoltaic elements A1, A2, or A3 in the predetermined positions of the support, a conductive adhesive is previously applied to the periphery of the opening in each support recess . The conductive adhesive serves to fix each element to the predetermined position of the support and electrically connect the second semiconductor layer to the second conductor layer.

According to a conventional procedure, for example, a conductive adhesive is previously applied to the electrode formed on the outer surface of the second semiconductor layer of an element, and this element is then positioned and then mounted on the recess of a support. As described above, this procedure presents the problem that when the element is mounted on the support, the conductive adhesive applied to the electrode tends to adhere to the inside face of the recess, thereby impairing the function of the inside face of the recess as reflective mirror Another problem is that the fixing of the element to the support and the electrical connection on the face of the second semiconductor layer are unreliable. In addition, there is also a productivity drawback since the stage of applying the conductive adhesive to the tiny electrode is difficult.

On the other hand, according to the present invention, when the element is mounted on the support, the conductive adhesive does not adhere to the inside face of the recess. Therefore, the fixing of the element and the electrical connection on the face of the second semiconductor layer can be achieved reliably without impairing the function as a reflective mirror. In addition, the conductive adhesive can be applied to the support at high speed by printing, transfer and the like.

A second feature of the production process according to the present invention is the use of the support separately from the electrical insulating layer, instead of the conventional two-layer support consisting of the second conductor layer and the electrical insulating layer that are attached in solidarity or the conventional three-layer support further comprising the first conductor layer. This support has a plurality of recesses, each recess being designed to cover a photovoltaic element, and the interior face of the recess functions as a reflective mirror. At least the surface of the support on the light receiving face is conductive and functions as the second conductor layer.

Furthermore, a third characteristic of the production process according to the present invention refers to the second characteristic. That is, after the electrical insulating layer is formed on the rear face of the support with the photovoltaic elements A1, A2, or A3 mounted thereon, through holes are formed in the electrical insulating layer to provide interconnecting conductive paths electrically the electrodes of the first semiconductors.

A first advantage derived from the second and third features of the present invention is that the electrical insulating layer, which comprises resin, is free from damage such as thermal deformation due to the heat treatment that is applied to solidify the conductive adhesive to fix the elements. to the support, since the support is separated from the electrical insulating layer. This solves the conventional problem of deformation of the conductive paths previously formed in the electrical insulating layer, which causes a displacement of the elements arranged in the recesses of the support and therefore an internal short circuit or a bad electrical connection.

A second advantage is that the support of the present invention, which usually has a single-layer metal structure, can be obtained with high precision by working a thin metal plate by pressure, cutting or the like. In the case of the conventional support with the two-layer or three-layer structure, a highly precise support cannot be obtained, due to the thermal deformation of the electrical insulating layer during the production of the support and the errors that can occur when laminating the layers. It is therefore difficult to mount elements in the predetermined positions.

A third advantage is that the displacement or thermal deformation of the conductive paths in the electrical insulating layer can be avoided. According to the present invention, the electrical insulating layer is formed on the rear face of the support with the elements mounted thereon and the through holes are formed therein in a predetermined pattern. Therefore, the conductive paths formed in this way are free of displacement. In addition, since the electrical insulating layer does not overheat, the conductive paths are free of deformation.

Furthermore, in the present invention, it is not always necessary to previously form an electrode for the second semiconductor. This is because unlike the first semiconductor, the second semiconductor layer has a low resistance since it contains a high concentration of an impurity diffused therein. The present inventors have experimentally found that the second semiconductor layer and the second conductor layer can be electrically connected with a low resistance without forming an electrode for the second semiconductor, applying a conductive paste containing, for example, a thermosetting resin or a frit of glass of low melting point as a binder between them and subjecting it to a heat treatment at about 100 to 500 ° C. Accordingly, it has become possible to electrically connect the second semiconductor layer to the second conductor layer without forming an electrode for the second semiconductor layer by directly joining the second semiconductor layer of each element disposed on the support to the inner face (layer of second conductor) of the recess of the support with a conductive adhesive and applying a heat treatment to it. Since this heat treatment can be performed at a relatively low temperature, it does not damage the support composed primarily of metal such as aluminum.

Hereinafter, the first to fifth preferred embodiments of the process for producing a photovoltaic device according to the present invention are specifically described step by step.

Embodiment 1

This embodiment aims at a production process in which steps (a) and (d) are performed, and then steps (e), (f), (b), (g), (h ), (c), e (i) in this order.

1-1) Stage (a)

At this stage, a plurality of photovoltaic elements A1 is prepared, each comprising a first spherical semiconductor and a second semiconductor layer that covers the entire surface thereof.

The first semiconductor can be produced, for example, by supplying p-type polycrystalline Si tablets containing traces of boron in a crucible, melting it in an atmosphere of inert gas, pouring the laundry from a tiny nozzle hole in the bottom of the crucible and cooling the droplets that are poured for solidification. The first resulting spherical semiconductor is a polycrystalline or monocrystalline semiconductor of type p. Usually, its surface is worn by friction, and the surface layer of approximately 50 µm is removed by chemical attack or the like before being used as the first spherical semiconductor.

The first p-type semiconductor is subjected to a heat treatment at 800 to 950 ° C for 10 to 30 minutes, using, for example, phosphorus oxychloride as a diffusion source, whereby a phosphorus diffusion layer is formed with a thickness of approximately 0.5 µm on the surface of the first p-type semiconductor as the second semiconductor layer, that is, the n-type semiconductor layer. The type n semiconductor layer can also be formed by CVD using a mixed gas, such as phosphine-containing silane.

Although element A1 as described above is configured so that the first semiconductor is a semiconductor of type p and the second semiconductor layer is a semiconductor layer of type n, element A1 can be configured so that the first semiconductor is a semiconductor type n and the second semiconductor layer is a p type semiconductor layer. The first semiconductor may be composed of a core material whose outer surface is covered with a layer of first semiconductor. Alternatively, the first semiconductor may be hollow around its center. Although it is preferred that the first semiconductor is completely spherical, it can be substantially spherical. The diameter of the first semiconductor from 0.5 to 2 mm, preferably from 0.8 to 1.2 mm.

In the case of element A1 with the anti-reflection coating formed on the second semiconductor layer, the second semiconductor layer is electrically connected to a support (second conductor layer) with the anti-reflection coating interposed therebetween, in step (f) which will be described later. Therefore, the antireflection coating of the present invention is conductive. For example, it is possible to use a thin film composed mainly of ZnO, SnO2, ITO (In2O3-Sn) or the like that is prepared by precipitation, atomization, spraying or the like.

In terms of conductivity and refractive index, it is particularly preferred that the anti-reflection coating comprises a tin oxide (SnO2) coating doped with at least one of fluorine (F) and antimony (Sb) and present a thickness of 50 to 100 nm . For example, a coating of SnO2 with an almost uniform thickness is formed on the surfaces of a large number of elements with a second semiconductor layer formed thereon, spraying fine particles of a solution with a doping material and a dissolved tin compound in it on the elements while the elements are heated on a heating plate at 400 to 600 ° C and rotated. The coating of SnO2 formed on the surface of the element with at least one of F and Sb is doped as a result of thermal decomposition of the fine particles of the solution on or near the surface of the element. Exemplary doping materials that can be used include ammonium fluoride, hydrofluoric acid, antimony pentachloride and antimony trichloride, and exemplary tin compounds that can be used include tin tetrachloride, dimethyltin dichloride and trimethyltin chloride. .

Since the coating of SnO2 is highly conductive, its use as a transparent conductive film of a photovoltaic device employing a flat plate type photovoltaic element has been examined. However, since such a coating has a relatively large thickness of 400 to 1000 nm, it shows a very high reflectance of approximately 12.3% when formed on the surface of a Si semiconductor. Therefore, it cannot function completely as an anti-reflection coating.

Although the element A1 as described in the preceding embodiment comprises a crystalline Si semiconductor, it may comprise a composite semiconductor or the like. It can also comprise an amorphous material, in addition to single crystal and polycrystalline. In addition, the element A1 may have a structure such as a pin type that has a non-doped layer at the interface between the first semiconductor and the second semiconductor layer, one of the MIS type, one of the Schottky barrier type, one of the homo type -union or one of hetero-union type.

1-2) Stage (d)

At this stage, a support is prepared. The support has a large number of recesses to cover the photovoltaic elements and also serves as a second conductor layer that is electrically connected with the second semiconductor layers of the elements. Therefore, the support must be conductive at least on the light receiving face.

Figure 3 is a plan view showing an exemplary part of a support that is prepared by pressing a thin aluminum plate with a thickness of 0.2 mm, and Figure 4 is a cross-sectional view taken as along line 4-4 of Figure 3. A support 15 has recesses 16 that are shaped like a honeycomb, and their opening edges are hexagonal and adjacent to each other. Each of the recesses 16 narrows towards the bottom and has an opening 17 at the bottom. The opening 17 is smaller than the outer diameter of each element.

If the support has a low thermal resistance, it is prone to deform or deteriorate in the heat treatment stage performed to fix the elements to the support. It is therefore preferred to use a support comprising heat resistant material such as metal. The main support material is preferably aluminum with a view to processability, conductivity, flexibility and costs, but it can be a conductive material such as copper, stainless steel or nickel. If a layer of a highly conductive and reflective material, such as silver (Ag), is formed on the inner face of each recess of the support by electrolytic coating, electronic deposition, vacuum deposition or the like, the functions of the support as a second layer driver and reflective mirror increase.

In addition to the support of Figure 3, it is also possible to use several supports as illustrated in Figures 5 and 6. Figure 5 shows a support comprising an aluminum or stainless steel substrate 25 having a large number of recesses 26, having each recess an opening 27 at the bottom, formed by printing or the like, with a reflective mirror layer 29, made from, for example, Ag, on the inner faces of the recesses 26. The reflective mirror layer 29 serves to significantly increase the output of the photovoltaic device.

Figure 6 shows an aluminum support 35 approximately 1.0 mm thick with a large number of recesses 36, each recess presenting an opening 37, formed by printing, cutting work or the like.

The heat treatment applied to connect the second semiconductor layer to the support in step (f), which will be described later, does not deform the supports described above made from a metallic material, even if a conductive paste of fried glass type is used Low temperature or resin type conductive paste as conductive adhesive. For example, a support made from aluminum does not deform even if the highest temperature of the heat treatment is as high as 550 ° C.

1-3) Stage (e)

At this stage, a conductive adhesive is applied to the periphery of each opening in the recess of the support prepared in step (d), to connect the second semiconductor layer of each photovoltaic element A1 to the support.

The conductive adhesive is preferably applied by transfer and screen printing. First, the transfer is described with reference to Figure 7. As illustrated in Figure 7 (1), a conductive adhesive 121 is placed on the flat surface of a metal plate 123, and moving a draining roller 120 towards the Right, the conductive adhesive 121 spreads finely on the plate 123, to form a conductive layer of adhesive 122 with a uniform thickness. The viscosity of the conductive adhesive is adjusted to approximately 100 Pa · s. Subsequently, as illustrated in Figure 7 (2), a transfer plate 125 is lowered, which has transfer pins 124 embedded therein at the same separation distances as those of the openings 17 of the support 15 of Figure 3 , in the vertical direction, and the edges 126 of the transfer pins 124 are brought into contact with the conductive adhesive layer 122. Next, as illustrated in Figure 7 (3), the transfer plate 125 is raised with a conductive adhesive 51 applied to the edges 126 of the transfer pins.

Then, as illustrated in Figure 7 (4), the transfer plate 125 is lowered towards the support 15 so that the centers of the recess 16 and the transfer pin 124 are aligned, and the edge 126 of the transfer pin against the periphery of the opening 17. Then, as illustrated in Figure 7 (5), the transfer pin 124 is raised. The edge 126 of the transfer pin is shaped as a ring, and the outer diameter it is larger than the diameter of the support opening by approximately 0.15 mm while the internal diameter is smaller than the diameter of the support opening by approximately 0.15 mm. As a result, the conductive adhesive 51 adhering to the edge 126 of the transfer pin is transferred to the periphery of the support opening 17, so that the conductive adhesive 51 is applied to the periphery of the support opening in the form of ring.

The edge of the transfer pin may be in the form of a circle slightly larger than the diameter of the opening of the support or may have a curved surface. Although the material of the transfer pin is not particularly limited, it is preferred to use a material that is relatively hard and excellent in chemical resistance, for example, a metal such as stainless steel, fluorocarbon resin or polypropylene.

Next, screen printing is described. Since the part to which the conductive adhesive is to be applied is located on the bottom of the support recesses, conventional screen printing cannot be used. In this embodiment, by printing the conductive adhesive from the back face of the support, the conductive adhesive is applied to an area that extends from the periphery of each opening on the rear face of the support to the periphery of the opening on the front face. As illustrated in Figure 8, the metal mask used in screen printing has a plurality of groups of openings 21 corresponding to the openings 17 of the support 15 of Figure 3. Each of the groups of openings 21 consists of six openings 22 which they are arranged along the opening edge of each opening 17. Each of the openings 22 is shaped so that it covers an area that extends from the outside of the opening edge of the opening 17 to the inside of it. . The thickness of the support 15 around the opening 17 is 0.12 mm, and the diameter of the opening 17 is 0.85 mm. The thickness of the metal mask is 50 µm, and the diameter of the opening 22 is 0.3 mm.

The metal mask is fitted on the rear face of the support 15 so that the centers of the openings 22 are located on the opening edge of the opening 17, and a paste-like conductive adhesive 13 is printed on the rear face of the support 15. As a result, as illustrated in Figure 9, the conductive adhesive 13 is applied to six locations around each opening 17 thereby covering the periphery of the opening 17, the inner wall of the opening 17, and the inner face of the recess 16. The conductive adhesive is, for example, a resin-like conductive paste composed of a mixture of an epoxy-type adhesive and an Ag powder that serves as a conductive agent, whose viscosity at 25 ° C is 20 Pa · s.

1-4) Stage (f)

At this stage, each of the photovoltaic elements A1 prepared in step (a) is arranged in each recess so that the second semiconductor layer thereof is in contact with the edge of the opening in the recess of the support, by which the second semiconductor layer joins the periphery of the opening with the conductive adhesive applied in step (e). In addition, the conductive adhesive is heated for solidification. This produces a structure B1 in which the elements A1 are fixed to the predetermined positions of the support so that their second semiconductor layers are electrically connected to the second conductor layer.

The process for producing the structure B1 is specifically described with reference to Figure 10. While the conductive adhesive applied to the support in step (e) is still adhesive before drying, the elements A1 are arranged in the predetermined positions of the support of the following form.

First, the air pressure on the rear face of a suction plate 131, in which a large number of suction holes 130 are formed in the same pattern as that of the openings 17 of the support 15, is reduced to aspirate the elements 10 of figure 1 inside the respective suction holes 130. The suction plate 131 moves to a position above the support 15 of Figure 7 (5) so that the centers of the suction holes 130 and the openings 17 are aligned, and the suction plate 131 is lowered as illustrated in figure 10 (1). The suction plate 131 is lowered until the second semiconductor layers 2 of the elements 10 come into contact with the peripheries of the openings 17 in the recesses 16 of the support, and then are pressed lightly while the air pressure on the the rear face of the suction plate 131 at a normal pressure. Subsequently, as illustrated in Figure 10 (2), the suction plate 131. is raised. As a result, each of the second semiconductor layers 2 adheres to the periphery of each opening 17 with the conductive adhesive 51, without causing that the conductive adhesive 51 adheres to the inside face of the recess 16 with the exception of the periphery of the opening 17.

The support 15 with the elements 10 arranged therein is heated to solidify the conductive adhesive 51, to produce a structure B1 in which the second semiconductor layers 2 of the elements 10 are firmly connected to the peripheries of the openings 17 of the support, as illustrated in Figure 11.

1-5) Stage (b)

In this stage, at least a part of the second semiconductor layer of each photovoltaic element A1 is removed on the rear face of the support of the structure B1 manufactured in the previous stage (f) to expose the first semiconductor. As a result, elements A1 become elements A2.

Specifically, to remove the surface layer (thickness: approximately 1 to 3 µm) of element A1 that includes the second semiconductor layer (thickness: less than 1 µm) chemical attack, sandblasting, brushing or a procedure is used that employs a combination of these. In the case of sandblasting, a fine abrasive powder is sprayed from a nozzle comprising, for example, alumina, together with air on the rear face of the structure B1, whereby the surface layer of the element A1 including The second semiconductor layer on the back face of the support is removed with the abrasive. In the case of brushing, the surface layer is worn by friction, for example, by rotating a nylon brush with diamond abrasive grains coupled thereto and putting it in contact with the surface of the element A1 exposed to the rear face of the support.

According to sandblasting and brushing, hard materials such as the anti-reflection coating and Si, particularly the anti-reflection coating, are easily worn by friction, but soft materials such as aluminum support and conductive adhesive do not wear out easily by friction. Therefore, according to these procedures, the surface layer of the element A1 on the rear face of the support can be removed without causing substantial damage to the support.

In the case of chemical attack, a chemical attack agent is placed in contact with the rear face of the structure B1 to dissolve and remove the surface layer of the second semiconductor layer, followed by washing with water and drying. For example, using a chemical attack agent composed of a mixture of approximately 60% concentration of hydrofluoric acid and approximately 40% concentration of nitric acid in a volume ratio of 4: 1, the chemical attack is carried out during 10 to 20 seconds As another chemical attack agent, it is also possible to use an alkaline aqueous solution in which tetramethylammonium hydroxide and an oxidizing agent, such as hydrogen peroxide, are dissolved.

Although these chemical attack agents dissolve Si and the anti-reflection coating, it is unlikely that they dissolve aluminum. Therefore, by properly adjusting conditions such as treatment time, only the surface layer of element A1 can be removed without causing substantial damage to the aluminum support. If a reflective mirror layer of Ag is formed on the surface of the support, it is preferred to use the above-mentioned alkaline aqueous solution that is unlikely to dissolve the Ag.

According to the sandblasting and brushing indicated above, particularly the anti-reflection coating of the surface layer of element A1 is easily removed. In contrast, depending on the chemical attack, the Si is more likely to be removed than the anti-reflection coating. Therefore, it is effective to use sandblasting or brushing to primarily remove the antireflection coating, and then use a chemical attack to primarily remove the semiconductor layer.

In addition, in the case of removing the second semiconductor layer only by sandblasting or brushing, it is also preferred to apply a light chemical attack to the surface to be worn by friction with the chemical attack agent indicated above and wash it with water, as appropriate, to facilitate the formation of an electrode at a later stage and avoid damaging the photovoltaic characteristics. According to the respective procedures mentioned above, a very thin surface layer of element A1 is removed, so that the resulting element A2 remains almost spherical. Figure 12 illustrates an exposed part 14 of the first semiconductor 1 formed on the rear face of the support 15 of the structure B1 of Figure 11.

In this step, in addition to the above procedures, it is also possible to employ a method of removing the part of the element A1 on the rear face of the support by grinding or the like so that the opening of the second semiconductor layer is flush with the exposed part of the first semiconductor. According to this procedure, after grinding, a load is applied to the element A1 fixed to the support from the rear face of the support. It is therefore necessary to give special consideration so that element A1 is not separated from the support by this load.

1-6) Stage (g)

At this stage, an electrical insulating layer is formed on the back face of the support with the photovoltaic elements A2 incorporated therein.

The electrical insulating layer can be formed, for example, by bonding a resin sheet to the back face of the support with an adhesive or by thermocompression bonding or the like. Examples of resin sheet materials that can be used include resins such as polyamide type, epoxy type, polyether ether ketone type, aromatic polyamide type, polyether sulfone type, polyetherimide type and fluorocarbon type.

Referring now to Figure 13, the method of forming the electrical insulator layer using a resin sheet is specifically described. As illustrated in Figure 13 (1), the support 15 of Figure 12 with the element A2 fixed thereto is placed with its light receiving surface below, and a polyether ether ketone resin sheet 38 is disposed on the back face of the support 15. Subsequently, a heat treatment is applied thereto at about 380 ° C for about 10 minutes, so that the resin sheet 38 is attached to the back face of the support 15, as illustrated in Figure 13 (2) . Although a thin resin sheet with a thickness of approximately 50 µm is used, its adhesion to the back face of the support is very good, and its strength is also sufficient.

Another process for forming the electrical insulating layer using a resin sheet is the procedure of using a semi-cured sheet composed primarily of a thermosetting resin, such as epoxy resin. According to this procedure, first, a resin sheet disposed on the back face of the support is pressed in the same way as in Figure 13 (1) with a heated hot rolling mill to a relatively low temperature of about 120 ° C. This roller preferably has an elastic sheet, such as rubber, coupled thereto. Through this heating, the semi-cured resin sheet becomes flexible and adhesive to a suitable degree without being cured. Therefore, by pressing the resin sheet as described above, the resin sheet can be attached to the back face of the support in the same manner as in Figure 13 (2).

If this resin sheet is not subjected to heat treatment to maintain the semi-cured sheet, the resin sheet functions as an adhesive in step (i), which will be described later. That is, by joining a conductive metal sheet to this resin sheet with a hot roller mill and then applying a heat treatment to cure the resin sheet, the support and the resin sheet, and the resin sheet and The metal sheet. In place of the above-mentioned process that uses a hot roller mill, it is also possible to stack the support and the resin sheet, or the resin sheet and the metal sheet, and heat them while reducing the air pressure in the space between the two stacked elements, to glue the two elements together. As a resin sheet, in addition to the thermosetting resin sheet, it is also possible to use a sheet comprising a thermosetting resin and, for example, glass fibers mixed therein.

Another procedure for forming the electrical insulating layer is the process of applying a resin paste by screen printing, spraying, offset printing or the like and drying it. As resin paste material, various resins such as epoxy type, polyamide type, silicone type, urethane type and acryl type can be used. With a view to costs and feasibility, the most preferable is the use of an epoxy resin. The resin paste is prepared by dissolving or dispersing such a resin material in an organic solvent

or water

1-7) Stage (h)

In this stage, through holes are formed in the electrical insulating layer prepared in the previous stage (g). These through holes are formed to expose at least a portion of the exposed part of the first semiconductor of each photovoltaic element A2 prepared in step (b). The through holes serve as conductive paths that interconnect the electrodes of the respective A3 elements in step (i) which will be described later.

To form such a through hole in the electrical insulating layer, it is preferred to irradiate the part of the electrical insulating layer to be removed with a laser beam so that the resin of the irradiated part is decomposed. Figure 13 (3) illustrates the step of forming a through hole in the electrical insulating layer of Figure 13 (2) prepared by joining the resin sheet to the back face of the support. A part or all of the part of the resin sheet 38 covering the exposed part 14 of the first semiconductor 1 is irradiated with a laser beam 28, to form a through hole 60 in the irradiated part of the resin sheet 38. Using a laser 50 W YAG as a laser beam irradiation device 59, and with an irradiation time of approximately 0.01 seconds, the irradiated part of the resin sheet 38 with a diameter of approximately 100 to 150 µm can be removed. In the case of using a semi-cured resin sheet of the epoxy resin type, almost the same conditions as those mentioned above can also be applied for the formation of a through hole. In the case of forming a through hole in the electrical insulating layer prepared by applying a resin paste to the back face of the support, the above procedure can also be applied.

1-8) Stage (c)

In this stage, an electrode is formed on the exposed surface of the first semiconductor within each through hole prepared in the previous stage (h). As a result, the photovoltaic elements A2 incorporated into the structure B1 become A3 elements.

Referring now to Figure 14, this stage is specifically described. First, the structure of Figure 14 (1) is prepared, in which the through holes 60 were formed in the electrical insulator layer 38 in the previous stage. As illustrated in Figure 14 (2), the through hole 60 is filled with a conductive paste 61 by printing or with a dispenser, to apply the conductive paste 61 to the exposed part 14 of the first semiconductor within the through hole 60.

Subsequently, the conductive paste 61 is heated locally by irradiating the conductive paste 61 with a laser beam, so that an electrode 62 is formed as illustrated in Figure 14 (3). Laser irradiation can be performed using, for example, a YAG laser, at a scanning speed of 1000 mm / s and a printing pulse rate of 10 µm. The conductive paste is preferably a conductive glass-type fried paste containing glass frit as a binder and a conductive agent such as silver or aluminum.

1-9) Stage (i)

In this stage, a first conductor layer is formed that electrically interconnects the electrodes of the photovoltaic elements A3 formed within the through holes of the electrical insulating layer in the previous stage (c). The through holes of the electrical insulating layer function as conductive paths to electrically interconnect the electrodes.

Specific procedures by way of example include a method of joining a conductive metal foil made of aluminum foil to the electrical insulating layer and a method of applying a conductive paste so as to interconnect the electrodes into the through holes of the layer of electrical insulator and solidifying it.

In the case of forming the first conductor layer using a metallic foil, first, each through hole of the electrical insulating layer is filled with a conductive paste, to apply the conductive paste to the electrode surface. Subsequently, using this conductive paste as an adhesive, a metal foil is attached to the surface of the electrical insulating layer. For example, as illustrated in Figure 15 (1), the through hole of the electrical insulating layer 38 is filled with a conductive paste 63. If necessary, as illustrated in Figure 15 (2), an adhesive is applied conductor 64 to the surface of the electrical insulating layer 38. Then, as illustrated in Figure 15 (3), a metal sheet 70 is attached thereto and subjected to a heat treatment to solidify the conductive paste 63 and the conductive adhesive 64. As a result, the metal sheet is bonded to the electrical insulating layer with the solidified conductive paste and the conductive adhesive, and is fixed to the face of the support. In this way, the electrodes 62 of the respective elements are electrically connected with the metal sheet 70, to form the first conductor layer.

In addition, when the semi-curable thermosetting resin sheet was used as an electrical insulating layer in step (g), first, the through hole of the electrical insulating layer is filled with a conductive paste to apply the conductive paste to the surface of the electrode. Then, as described in 1-6), a metal foil is placed on the electrical insulating layer, and they are joined together under pressure with a hot roll mill heated to approximately 120 ° C, followed by a heat treatment at 150 at 200 ° C. Figure 16 illustrates the resulting first conductor layer. According to this procedure, the metal sheet 70 is firmly attached to an electrical insulating layer 71 comprising a thermosetting resin sheet, without the need to use the conductive adhesive 64 of Figure 15 applied to the surface of the electrical insulating layer. As a result, the respective electrodes 62 are electrically connected to the metal sheet 70 reliably. The conductive metal foil used in the aforementioned procedures can be, for example, a thin plate with a thickness of about 50 to 100 µm, comprising nickel, copper or stainless steel, in addition to aluminum.

Next, the process of forming the first conductor layer by applying a conductive paste is described below, so that the electrodes are interconnected within the through holes of the electrical insulating layer and solidify the conductive paste. The conductive paste can be applied by dispensing, screen printing, offset printing and spraying. If the back face of the support is irregular, dispensing and spraying are preferred since these procedures can apply a conductive paste even to depressions of the irregular surface.

Figure 17 illustrates the step of forming the first conductor layer by applying a conductive paste by dispensing and applying a heat treatment. As illustrated in Figure 17 (1), when dispensing a conductive paste 31 from a nozzle 36 of a dispenser, the nozzle 36 moves along the straight line connecting the electrodes 62 into the respective through holes in the electrical insulating layer 38 on the rear face of the support 15 of the structure of Figure 14 (3). As a result, as illustrated in Figure 17 (2), a conductive paste coating layer 32 is formed in the form of a line on the electrical insulator layer 38. This coating layer 32 interconnects the electrodes 62 of the respective elements fixed to the support 15 on the electrical insulating layer 38.

Figure 18 illustrates the application pattern of the coating layer 32 formed in the above manner. Figure 18 is a plan view of the rear face of the support 15 with the coating layers 32 of conductive paste formed in the stage of Figure 17. For simplicity, details such as electrodes and holes are omitted from the figure through the electrical insulating layer. The coating layers 32 are formed on the electrical insulating layer 38 so that the electrodes of the elements fixed to the large number of recesses 16 that are aligned in straight lines interconnect. The line width of each coating layer 32 is slightly smaller than the diameter of each opening 17 of the support and substantially equal to the diameter of the exposed part of each first semiconductor. Judging from the electrical characteristics of the photovoltaic device, the line width of the coating layer 32 should be 310 µm or more. The respective edges of the coating layers 32 that are aligned in parallel are connected by a linear coating layer 39 of conductive paste formed on the edge of the support 15.

In addition to the application pattern described above, it is also possible to employ, for example, a network type pattern consisting of linear coating layers of conductive paste, in which respective electrodes meet at the intersections of the linear coating layers. That is, the application pattern can be such that the respective electrodes of the elements A3 mounted on the support are isolated from the support and the second semiconductor layers by means of the electrical insulator layer while interconnecting in one way or another with the conductive paste For example, the conductive paste can be applied to the entire surface of the electrical insulating layer by printing.

By applying a heat treatment to the conductive paste coating layer, a first conductive layer comprising the solidified conductive paste is formed. According to this procedure, the first conductor layer can be formed at high speed, and the number of components can be reduced.

It is preferred that the conductive paste and conductive adhesive used in the above processes solidify at temperatures that do not cause damage, such as deformation or deterioration, to the electrical insulating layer. Normally, a resin-type conductive paste is used which solidifies at a relatively low heat treatment temperature of 100 to 200 ° C. When the electrical insulating layer is composed of a material with a relatively high thermal resistance, such as fluorocarbon resin, a conductive paste of low temperature glass fried type can be used.

Embodiment 2

This embodiment aims at a production process in which steps (a) and (d) are performed and then steps (e), (f), (b), (c), (g), ( h) e (i) in this order.

This embodiment is the same as embodiment 1 until the exposed part of the first semiconductor is formed on each photovoltaic element A1 incorporated into the structure B1, but differs from the embodiment 1 in that the electrode is formed before the layer is formed of electrical insulator.

2-1) Stages (a), (d), (e), (f) and (b)

Through these steps, a structure B1 is formed, and the second semiconductor layer of each photovoltaic element A1 on the rear face of the support is removed. As a result, elements A1 become elements A2. These steps can be carried out by absolutely the same procedures and sequence as those of embodiment 1.

2-2) Stage (c)

In this stage, an electrode is formed on the exposed part of the first semiconductor of each photovoltaic element A2 prepared in the previous stage (b). As a result, the A2 elements become A3 elements. Figure 19 illustrates this stage. First, as illustrated in Figure 19 (1), a conductive paste 65 is applied to the exposed part 14 of the first semiconductor of the structure of Figure 12 by printing or with a dispenser. Then, as illustrated in Figure 19 (2), an electrode 67 is formed by irradiating locally the applied part of the conductive paste 65 with a laser beam to heat it. The laser irradiation process and the conductive paste used are the same as those described in 1-8) of embodiment 1.

2-3) Stages (g) and (h)

In this embodiment 2, after the previous step (c) of forming the electrode on the exposed part of the first semiconductor, step (g) is performed to form an electrical insulating layer on the back face of the support, and then step (h) is performed to form through holes in the electrical insulator layer to expose the electrodes. Since the steps (g) and (h) are the same as those of embodiment 1 except that the base underlying the electrical insulating layer is slightly different, they can be carried out according to the procedures as described in 1- 6) and 1-7) of the embodiment 1. Examples are illustrated by way of example in Figure 20 (1) and Figure 20 (2). Figure 20 (1) illustrates an electrical insulator layer 71, comprising a thermosetting resin sheet, bonded to the rear face of the structure of Figure 19 (2), and Figure 20 (2) illustrates the insulator layer electric 71 with a through hole 68 formed therein.

2-4) Stage (i)

In this stage, a first conductor layer is formed that electrically interconnects the electrodes of the photovoltaic elements A3, with the through holes of the electrical insulating layer formed in the previous stage (h) as conductive paths.

Specifically, the same procedures as those in Figures 15 to 18 as described in 1-9) of embodiment 1 can be performed. For example, as illustrated in Figure 20 (3), the through hole of the layer The electrical insulator 71 of Figure 20 (2) is filled with a conductive paste 80 to apply the conductive paste 80 on the electrode 67, and a metallic foil 70 is attached to the electrical insulator layer 71.

In 2-1) to 2-4) above, the second preferred embodiment of the production method of the photovoltaic device according to the present invention has been described. Hereinafter, other modifications encompassed by the second embodiment are described. This production process is absolutely the same as the previous one until stage (c), but the later stages (g), (h) and (i) are different.

In this procedure, as a stage corresponding to stage (g), an electrical insulating layer and a conductive metal sheet are glued to the rear face of the structure support with the electrodes formed in the stage

(c) from 2-2). Subsequently, as a stage corresponding to stage (h), through holes are formed in the electrical insulating layer and the metal sheet to expose the electrodes of the elements A3. Then, as step (i), the through holes are filled with a conductive paste, and a heat treatment is applied to solidify the conductive paste. As a result, the electrodes are electrically connected to the metal sheet with the solidified conductive paste inside the through holes, with the electrical insulator layer interposed therebetween, to form a first conductor layer.

A preferred procedure is as set forth below. In step (g), first, an electrically insulating adhesive layer is formed on the back face of the support. Next, a composite sheet consisting of a conductive metal sheet and an electrical insulating layer bonded to one side of the conductive metal sheet is prepared, and the electrical insulating layer of the composite sheet is attached to the layer of adhesive. The adhesive layer is formed by applying a paste type adhesive by screen printing, spraying, offset printing or the like. As an adhesive material, for example, epoxy type resin, polyamide type, silicone type, urethane type or acryl type are used. An exemplary preferred composite sheet is composed of an electrical insulating layer comprising a 25 µm thick polyethylene terephthalate film and a 20 µm thick aluminum sheet bonded to the electrical insulating layer.

This production process is illustrated in Figure 21A and Figure 21B. First, as illustrated in Figure 21A (1), a layer of adhesive 69 is formed on the rear face of the support 15 of the structure of Figure 19 (2). Subsequently, as illustrated in Figure 21A (2), a composite sheet 90 consisting of a metallic sheet 92 and an electrical insulator layer 91 is placed on the adhesive layer 69 of the support 15, and the insulator layer Electric 91 of the composite sheet 90 is glued to the support 15 while the pressure between them is reduced. As illustrated in Figure 21B (3), the composite sheet 90 adheres the adhesive layer 69 on and around the electrode 67 of the element. When the support 15 is composed of a thin metal foil, the adhesive layer on the rear faces of the separations between the recesses produces the effect of reinforcing the separations of the support and the effect of fixing the elements more firmly to the support. Once the composite sheet is bonded, a heat treatment is applied to solidify or cure the adhesive layer, if necessary. At this stage, it is also possible to glue the resin sheet of the electrical insulating layer or the insulating adhesive layer to the back face of the support and then bond the metal sheet to it.

Next, the part corresponding to the center of the opening 17 of the support is irradiated with a laser beam. As a result, as illustrated in Figure 21B (4), the irradiated part of the metal sheet 92, the electrical insulator layer 91 and the adhesive layer 69 are removed, to form a through hole 93 into which the electrode 67. Using a YAG laser with an output power of 12 W as an irradiation device of the laser beam, and with an irradiation time of approximately 0.017 seconds, the through hole 93 with a diameter of approximately 100 to 150 µm can be formed.

Then, as illustrated in Figure 21B (5), the through hole 93 is filled with a conductive paste 94 to connect the electrode 67 of each element to the metallic sheet 92 with the conductive paste. The conductive paste is preferably a resin type conductive paste. If the material of the electrical insulating layer has a relatively high thermal resistance, such as fluorocarbon resin, a conductive paste of low temperature glass frit type can also be used. The conductive paste can be applied by dispensing, screen printing, offset printing, and spraying.

Embodiment 3

This embodiment aims at a production process in which steps (a) and

(d) and then steps (e), (f), (g), (h), (b), (c), e (i) are performed in this order. This embodiment is the same as embodiments 1 and 2 until structure B1 is formed. Then, the through holes are formed in the electrical insulating layer on the rear face of the structure B1 to expose the first semiconductors within the through holes, and the electrode is formed on the exposed surfaces of the first semiconductors.

3-1) Stages (a), (d), (e), and (f)

Through these stages, a structure B1 is manufactured with photovoltaic elements A1 fixed to the support. These steps are carried out by absolutely the same procedures and sequence as those of embodiment 1.

3-2) Stages (g) and (h)

In this embodiment, step (g) is performed to form an electrical insulator layer on the rear face of structure B1, and then step (h) is made to make through holes in the electrical insulator layer to expose the second semiconductor layers in them. The sequence of these stages is different from that of embodiment 1 in which the exposed parts of the first semiconductors are formed, the electrical insulator layer is formed, and the through holes are made in the electrical insulator layer. In these two embodiments, the base underlying the electrical insulating layer is slightly different. However, in this embodiment 3, steps (g) and (h) can be performed according to the procedures described in 1-6) and 1-7) of embodiment 1. Representative examples are shown in Figure 22 (1) and Figure 22 (2). Figure 22 (1) illustrates an electrical insulator layer 71, comprising a thermosetting resin sheet, attached to the rear face of the support 15 of the structure of Figure 11, and Figure 22 (2) illustrates the insulation layer electric 71 with a through hole 95 formed therein to expose the second semiconductor layer 2.

3-3) Stage (b)

In this stage, the second semiconductor layer that is exposed within the through hole 95 formed in the previous step (h) is removed. As a result, the photovoltaic elements A1 incorporated in the structure B1 become A2 elements with a part of the first semiconductor exposed.

In this embodiment, the chemical attack is appropriate as a procedure to remove the second semiconductor layer. This is because the electrical insulating layer bonded to the back face of the support prevents the surface of the support from coming into contact with a chemical attack agent and wear. For example, a chemical attack agent, which may be the liquid mixture of hydrofluoric acid and nitric acid used in 1-5) of embodiment 1, is contacted only with the back face of the support for approximately 20 seconds, followed by washing with water and drying. As a result, as illustrated in Figure 22 (3), the surface layer approximately 1 to 3 µm deep which includes the second semiconductor layer 2 within the through hole 95 is removed, so that an exposed portion 96 is formed of the first semiconductor 1 in the through hole.

3-4) Stage (c)

In this stage, an electrode is formed on the exposed surface of the first semiconductor of the photovoltaic element A2 prepared in the previous step (b) within the through hole 95. As a result, the elements A2 become elements A3.

In this step, the electrode can be formed by the same procedure as in 1-8) of embodiment 1. Figure 22 (4) illustrates an electrode 97 formed on the exposed part 96 of the first semiconductor inside the through hole 95 of the electrical insulating layer.

3-5) Stage (i)

In this stage, a first conductor layer is formed which electrically interconnects the electrodes of the photovoltaic elements A3, with the through holes 95 made in the previous stage (h) as conductive paths.

In the same way as in 1-9) of the embodiment 1, this step can be carried out by the method of joining a conductive metal sheet to the electrical insulating layer with a conductive adhesive, the procedure of applying a conductive paste so which interconnects the electrodes inside the through holes of the electrical insulating layer and solidify it, or the like. For example, as illustrated in Figure 22 (5), the electrode 97 of each element is electrically connected to a metal sheet 70 with a conductive paste 98 with which the through hole 95 of the electrical insulating layer 71 has been filled .

Embodiment 4

This embodiment aims at a production process in which steps (a), (b), (c), and (d) are performed and then stages (e), (f), (g ), (h), e (i) in this order.

This embodiment is different from the embodiments 1 to 3 in which the photovoltaic elements A1 are mounted on the support to manufacture the structure B1. Instead, A3 photovoltaic elements with electrodes are mounted on the support to manufacture a B2 structure, and through this stage, a photovoltaic device is produced.

4-1) Stage (a)

At this stage, a plurality of photovoltaic elements A1 are prepared by the same procedure as that of 1-1) of embodiment 1.

4-2) Stage (b)

At this stage, at least a part of the first semiconductor of each photovoltaic element A1 prepared in the previous step (a) to obtain elements A2 is exposed.

A preferred method of this step is a method of removing a part of the elements A1 by grinding. Specifically, first, a support element is prepared that has a large number of recesses in a predetermined pattern, each recess having a predetermined depth. The elements A1 are placed in the respective recesses so that a part thereof is exposed. Subsequently, molten wax is applied to the support element and cooled for solidification. As a result, the elements A1 are fixed to the recesses of the support element with the solidified wax. A rotary grinding machine is then pressed against the exposed part of each element A1 to rectify and eliminate the exposed part of the element A1. Then, the wax is heated for evaporation or thermal decomposition to remove the wax from the surface of the element.

Figure 23 shows a cross section of the element A2 produced in the previous procedure, and Figure 24 shows a lower face thereof. A part of the first semiconductor 1 covered with the second semiconductor layer 2 is cut and removed, and an opening 3 of the second semiconductor layer is formed in the circumference of the cross section of straight cut. An exposed part 4 of the first semiconductor layer is formed within the opening 3. The central angle θ formed by connecting the central point of the element A2 to two opposite points on the circumference of the opening can be 45 to 90 °, and preferably from 60 to 90 °. In this case, the opening area is suitable for electrically connecting the first semiconductor to the first conductor layer.

Element A2 can also be obtained by covering the surface of element A1, except for a part thereof, with paraffin or the like, and applying a chemical attack process to remove the part of the second semiconductor layer out of the covered part. Figure 25 shows a cross section of the element A2 obtained in this procedure. Since the second semiconductor layer 2 is very thin, the external shape of element A2 of Figure 25 remains almost unchanged from that of element A1, in the same way as in element 10 of Figure 12.

4-3) Stage (c)

In this stage, an electrode is formed on the exposed part of the first semiconductor of each photovoltaic element A2 prepared in step (b) above, to obtain A3 elements.

The electrode can be formed, for example, by applying a conductive paste to the exposed part of the first semiconductor of the element A2 and applying a heat treatment to it. When the first semiconductor is a p-type semiconductor, it is preferred to use a conductive glass frit type paste in which aluminum powder or a mixture of aluminum powder and silver powder or the like is dispersed as a conductive agent. When the first semiconductor is a n-type semiconductor, it is preferred to use a mixture of a phosphorous compound and Ag powder as a conductive agent. Drying the applied conductive paste and applying a heat treatment, a good conductive layer (electrode) is obtained.

Specifically, in step (b) above, according to the procedure as described in 4-2), the elements A1 are fixed to the large number of recesses of the support element with the wax, and the parts of the exposed elements A1 from the recesses are rectified to expose the first semiconductors, to produce A2 elements. The A2 elements are left fixed to the support element as they are. At this stage, a conductive paste is applied by printing or similar to the exposed parts of the first semiconductors of the elements A2 fixed to the recesses in the predetermined pattern, followed by heating at 400 to 800 ° C. As a result, the wax is removed from the surfaces of the elements by evaporation or thermal decomposition, and at the same time, the electrodes are formed. In this case, it is also possible to remove the wax by heating to 400 to 600 ° C, moving the elements A2 from the support element to another container, and applying a heat treatment at 650 to 800 ° C to form the electrodes.

By means of the heat treatment mentioned above, a diffusion layer or alloy layer of the conductive agent contained in the conductive paste is formed on the surfaces of the first semiconductors, and at the same time, with molten glass frit acting as a binder, a resistant electrode. Due to the action of the alloy layer or diffusion layer, the contact resistance at the junction between the first semiconductor and the electrode becomes small.

Figure 26 shows a cross section of the element A3 with an electrode 5 formed on the exposed part 4 of the first semiconductor of the element A2 of Figure 23. The electrode 5 can be formed by applying a conductive paste with a dispenser to a circular central part of the exposed part 4 with a diameter of approximately 300 µm at a speed of 2 points / second, and applying a heat treatment. The conductive paste can also be applied by screen printing, offset printing or inkjet. The shape of the electrode can be oval, polygonal, ring-shaped, and in the form of a set of points, as well as circular.

As will be detailed later in step (f) of this embodiment, there is a procedure for placing the element A3 in the predetermined position of the support recess making the electrode or the vicinity thereof more magnetic than other parts and using magnetism. Hereinafter, the item to which this procedure applies is described.

The magnetic electrode can be formed using a conductive paste of glass frit type that additionally contains a powder of ferromagnetic substance such as Ni or Fe. By the same procedure as that of the electrode of element A3 of Figure 26, the electrode can be obtained from The same way. The surroundings of the electrode can be strongly magnetized forming a layer of magnetic substance that contains a ferromagnetic substance around the electrode. The magnetic substance layer can be formed by applying a paste to form a magnetic substance layer on or around the electrode with a dispenser or the like and applying a heat treatment. The paste to form the magnetic substance layer is, for example, a dispersion of a conductive ferromagnetic substance powder such as Ni or Fe and, if necessary, a conductive agent such as Ag in an organic solvent, a thermosetting resin, or Similary.

Figure 27 (1) illustrates a cross section of the element A3 with a layer of magnetic substance 6 formed on the electrode 5 of the element of Figure 26, and Figure 27 (2) illustrates a section of the element A3 with a layer of substance magnetic 7 formed around electrode 5.

4-4) Stages (d) and (e)

In step (d) a support is prepared in which the photovoltaic elements A3 are to be mounted, and in step (e) a conductive adhesive is applied to the peripheries of the support openings. These steps can be performed by the same procedures as those in 1-2) and 1-3) of embodiment 1.

4-5) Stage (f)

In this stage, the photovoltaic elements A3 are mounted in a specific orientation in the support so that their second semiconductor layers are in contact with the edges of the openings of the support to which the conductive adhesive was applied in the previous step (e) . As a result, a structure B2 is manufactured in which the second semiconductor layers of the elements A3 are electrically and physically connected to the support with the conductive adhesive.

Referring now to Figure 28A and Figure 28B, a first process for manufacturing the structure B2 is described. First, as illustrated in Figure 28A (1), a temporary substrate 81 is prepared which has a large number of cavities 80 to temporarily cover elements in the same pattern as that of the recesses 16 of the support 15 of Figure 3 The diameter of an upper opening 88 of each cavity 80 is slightly larger than the diameter of the element of Figure 23. The lower part of each cavity 80 has a through hole.

84. The through hole 84 has an upper opening 83, which is slightly larger than the opening 3 of the second semiconductor, and a lower opening 82, which is smaller than the opening 3. Subsequently, a large number of the elements of Figure 26 they are rolled on the temporary substrate 81, so that elements 85, 86, and 87 are coated in cavities 80 in random orientations.

Next, as illustrated in Figure 28A (2), a sliding plate 89, consisting of a sponge sheet 101 attached to a flat resin plate 100, moves slightly from left to right so that it brushes the face lightly upper of the temporary substrate 81 with the elements temporarily arranged inside. As a result, the parts of the elements 85, 86, and 87 that protrude from the cavities 80 are rubbed by the sponge sheet 101, so that the elements 85, 86, and 87 slide and rotate within the cavities 80 in the address shown by the arrow. For example, the orientation of element 85 changes to that of element 86 and then to that of element 87.

If the operation of moving the slide plate 89 from left to right continues, each element rotates until the electrode 5 is positioned in the center of the upper opening 88 of the cavity 80. At this time, since no part of the element protrudes from the cavity 80 and no external force is applied to the element by the movement of the sliding plate 89, the rotation of the element stops. Repeating the operation of moving the slide plate 89 several times, all elements 85, 86, and 87 are finally coated in the cavities 80 with their electrodes facing upwards, as illustrated in Figure 28A (3).

Subsequently, as illustrated in Figure 28B (4), the support 15 of Figure 7 (5) with the conductive paste 51 applied thereto, and the temporary substrate 81 of Figure 28A (3) with the elements coated in the controlled orientation, they are laminated so that the centers of the recesses 16 and the corresponding cavities 80 of the temporary substrate are facing each other. On the rear face of the temporary substrate 81, a plate 104 is provided that has projections 103, smaller than the openings 82, in the same pattern as that of the through holes 84. Pushing the plate 104 up to insert the projections 103 into the cavities 80 through through holes 84, elements 85, 86, and 87 are pushed into recesses 16. As a result, as illustrated in Figure 28B (5), elements 85, 86, and 87 are they are placed in the predetermined positions of the support in the specific orientation, and at the same time, the elements are temporarily fixed to the support with their second semiconductor layers 2 glued to the edges or peripheries of the openings 17 with the conductive adhesive 51. This stage is performed before the conductive adhesive applied to the support solidifies.

Then, by applying a heat treatment to the conductive adhesive applied to the support for its solidification, the correctly positioned elements are fixed maintaining their orientation, and their second semiconductor layers are electrically connected to the second conductor layer. This produces a B2 structure. When a resin-like conductive paste is used as a conductive adhesive, it is subjected to a heat treatment at 100 to 150 ° C for 10 to 20 minutes. When a low temperature glass frit type conductive paste is used, it is dried at about 100 to 150 ° C and then subjected to a heat treatment at about 500 ° C for 10 to 20 minutes.

Next, a second procedure for manufacturing the B2 structure is described. This procedure includes the step of applying a magnetic field to A3 elements whose electrodes or the vicinity thereof are more magnetic than other parts from a predetermined direction to align the electrodes of the A3 elements in a predetermined orientation. In a preferred mode of this positioning procedure, firstly, the elements A3 are placed in predetermined positions of a temporary positioning element, and a magnetic field is applied to the elements A3 from a predetermined direction to align the electrodes of the elements A3 in a default orientation. Subsequently, by transferring the elements A3 to the support while maintaining this alignment, the elements A3 are positioned so that the exposed part of each first semiconductor with the electrode formed on it protrudes through the rear face of the support from the opening of the recess.

This positioning procedure is specifically described with reference to Figures 29 to 31. First, by the step as shown by Figure 29, the elements of Figure 27 (2) are temporarily placed in random orientations on an element. of temporary placement consisting of a suction / separation filter 40 and an alignment filter 50. The suction / separation filter 40 has a large number of projections 42 in the same pattern as that of the support recesses. In the central part of each projection 42 a suction / separation hole 41 is formed, which is slightly smaller than the exposed part 4 of the first semiconductor of each element 20. The alignment filter 50 has a large number of temporary placement holes 48 , which are slightly larger than the elements 20 and slightly smaller than the projections 42, in the same pattern as that of the suction / separation holes 41.

As illustrated in Fig. 29 (1), the alignment filter 50 is laminated on the suction / separation filter 40 so that the centers of the suction / separation holes 41 and the corresponding temporary placement holes 48 align. Next, while vibrations are applied thereto and by reducing the air pressure on the side of the suction / separation filter 40, a large number of the elements 20 are rolled over the alignment filter 50. As a result, the elements 20 they are sucked into the suction / separation holes 41 and the elements 20 are temporarily placed in all temporary placement holes 48 in random orientations, as illustrated in Figure 29 (2). Excess elements 20 are removed by tilting the temporary placement element.

Referring now to Figure 30, the step of aligning the elements 20 in a specific orientation is described by applying a magnetic field to the elements 20 temporarily placed in the temporary placement element from a predetermined direction. As a means to apply a magnetic field to the elements 20, a set 118 of plate-shaped magnets is used. The magnet assembly 118 consists of a plurality of rectangular magnets 111 joined in parallel. A magnetic field is applied to the elements 20 from the plane perpendicular to the junction between adjacent magnets 111A and 111B of the magnet assembly 118, so that the magnetic substance layers of the elements 20 are attracted and aligned in an orientation predetermined by the attraction force of the joints 105 between magnets. The use of a set of magnets 111 allows the joints 105 between magnets to produce a greater magnetic force than the use of magnets separated from each other.

First, a composite magnet 110 is prepared that includes the magnet assembly 118 consisting of the plurality of narrow magnets 111 with a rectangular cross section. The magnet assembly is structured so that magnetic poles of different polarities are alternately arranged in the plane perpendicular to the junction of the magnets 111A and 111B. The composite magnet 110 comprises a rear cylinder head plate 119 which is jointly joined to the magnet assembly by the force of attraction of the magnet assembly. Next, a separator 115 is placed on the edge of the temporary positioning element of Figure 29 (2) with the elements 20 temporarily placed therein, and the magnetic force generation plane of the composite magnet 110 approaches the element of temporary placement, as illustrated in Figure 30 (1). At this time, the joints between magnets 105 of the magnetic force generation plane are opposite the centers of the temporary positioning holes 48 of the alignment filter 50.

Subsequently, by lowering the composite magnet 110 vertically and placing it on the separator 115, a magnetic field is applied to the elements 20 so that the force of attraction is applied to the centers of the elements

20. At the same time, by pressurizing the air on the rear face of the suction / separation filter 40, buoyancy is provided to the elements 20 from the suction / separation holes 41. This buoyancy allows the elements 20 to float in the holes 48, At a time when the layer of magnetic substance 7 is positioned upwards in each hole 48. At this time, due to the force of attraction, the layer of magnetic substance 7 is attracted towards the union between magnets 105. As a result, As illustrated in Figure 30 (2), the orientations of all elements 20 are controlled so that the exposed parts of the first semiconductors with the electrodes 5 and the layers of magnetic substance 7 formed thereon are oriented upward.

Next, by reducing the air pressure on the rear face of the suction / separation filter 40, the elements 20 are separated from the composite magnet 110 and are sucked into the suction / separation holes 41 while their orientations are maintained. As a result, as illustrated in Figure 30 (3), all elements 20 are aligned in the predetermined orientation in the suction / separation holes 41 of the suction / separation filter. Then, while maintaining the reduced pressure, the composite magnet 110 is removed and the alignment filter 50 is raised, so that the alignment filter 50 is separated from the suction / separation filter 40 with the elements 20 sucked towards the same. Figure 30 (4) illustrates all the elements 20 arranged in the predetermined positions of the suction / separation filter 40 in the predetermined orientation.

Next, by transferring the elements 20 arranged in the temporary positioning element to the support while maintaining its state, the elements 20 are positioned in the support. Figure 31 illustrates this stage. First, the support 15 of Figure 7 (5) is prepared with the conductive adhesive applied to the peripheries of the openings

17. Next, as illustrated in Figure 31 (1), the support 15 is placed near the suction / separation filter 40 of Figure 30 (4) with the elements 20 sucked thereto so that the centers of the recesses 16 are opposite the centers of the corresponding holes 41 of the suction / separation filter 40.

Subsequently, the support 15 is lowered and placed on the suction / separation filter 40. As a result, as illustrated in Figure 31 (2), the opening periphery of the second semiconductor layer 2 of each element 20 is adjusted at each opening 17, and the opening of the second semiconductor layer 2, the exposed part 4 of the first semiconductor, and the electrode 5 and the magnetic substance layer 7 protrude through the rear face of the support 15. At this time, The opening periphery of the second semiconductor layer 2 adheres to the conductive adhesive 51 applied to the periphery of the opening 17 of each recess, so that the elements 20 are temporarily fixed in the predetermined orientation.

To make this temporary fixation more reliable, the step can be performed as illustrated in Figure 31 (3). Specifically, the support 15 is fixed while maintaining its position, and the air on the rear face of the suction / separation filter 40 is pressurized to push up the elements 20 from the holes 41. Applying a heat treatment to it solidify the conductive adhesive 51, the elements 20 are fixed and the support 15 is electrically connected to the second semiconductor layers 2. The conductive adhesive and its heat treatment conditions can be the same as in the first manufacturing process of the structure B2.

4-6) Stages (g), (h), e (i)

The step (g) is performed to form an electrical insulating layer on the rear face of the support of the structure B2 prepared in the previous step (f). Next step (h) is performed to form through holes in the electrical insulating layer to expose the electrodes of the photovoltaic elements A3. Then, step (i) is performed to form a first conductor layer that electrically interconnects the electrodes with the through holes as conductive paths.

These steps can be carried out by the same procedures described in 2-3) and 2-4) of embodiment 2. Figure 32 illustrates a representative procedure thereof. An electrical insulator layer 71 is attached to the rear face of the support 15 of the structure B2 of Figure 32 (1). As illustrated in Figure 32 (2), a through hole 73 is then made in the electrical insulator layer 71 to expose the electrode 5 inside. Subsequently, the through hole 73 is filled with a conductive paste 74, and as illustrated in Figure 32 (3), a metal foil 70 is connected to the electrical insulating layer 71, to form a first conductive layer.

In addition, the procedures of steps (g), (h), and (i) described above as modifications in embodiment 2 can also be performed in this embodiment 4. Figure 33 illustrates a specific example of this procedure. As illustrated in Figure 33 (1), an electrical insulator layer 91 and a metal sheet 92 are attached to the rear face of the support 15 of the structure B2 with an adhesive layer 69 interposed therebetween. Next, as illustrated in Figure 33 (2), a through hole 77 is made in the electrical insulator layer 91 and the metal sheet 92. Then, as illustrated in Figure 33 (3), it is filled with a conductive paste 78 through hole 77, to form a first conductor layer.

Embodiment 5

This embodiment aims at a production process in which steps (a), (b), and (d) are performed and then steps (e), (f), (g), (h ), (c), e (i) in this order. In this embodiment, the photovoltaic elements A2, which each have an exposed part of the first semiconductor but which do not have any electrode, are mounted on a support for manufacturing a structure B3, and by this stage, a photovoltaic device is produced.

5-1) Stages (a) and (b)

Step (a) is performed to prepare a plurality of photovoltaic elements A1, and then step (b) is performed to convert these elements A1 into elements A2. These steps are carried out by the same procedures described in 4-1) and 4-2) of the embodiment 4.

5-2) Stages (d) and stage (e)

Step (d) is performed to prepare a support in which the photovoltaic elements A2 are to be arranged, and step (e) is then carried out to apply a conductive adhesive to the peripheries of the support openings. These steps are carried out by the same procedures described in 1-2) and 1-3) of the embodiment 1.

5-3) Stage (f)

At this stage, the photovoltaic elements A2 are mounted on the support in a specific orientation so that their second semiconductor layers are in contact with the edges of the openings of the support to which the conductive adhesive was applied in the previous step (e) . As a result, a structure B3 is manufactured in which the second semiconductor layers are electrically and physically connected to the support.

In this embodiment, the elements A2 that do not have any electrode are mounted on the support, while in embodiment 4, the elements A3 with electrodes are arranged on the support. Although this difference exists between them, in fact the elements A2 and the elements A3 have substantially the same shape and dimensions, since the electrode is a thin layer with a thickness of approximately 5 to 20 µm. Therefore, this step can be carried out according to the first manufacturing process of the structure B2 as described in 4-5) of embodiment 4. Figure 34 (1) illustrates the structure B3 obtained in this stage by assembling the elements A2 of figure 23 on the support 15 of figure 7 (5).

5-4) Stages (g) and (h)

The step (g) is performed to form an electrical insulating layer 71 on the rear face of the support 15 of the structure B3 manufactured in the previous stage (f), and then the step (h) is made to make the through holes 75 in the electrical insulator layer 71. These steps can be carried out by the same procedures described in 1-6) and 1-7) of embodiment 1. Figure 34 (2) illustrates the through hole 75 in the insulator layer electric 71 on the rear face of the support 15.

5-5) Stages (c) e (i)

The step (c) is carried out to form an electrode on the exposed surfaces of the first semiconductors within the through holes 75 made in the previous stage (h), by means of which the photovoltaic elements A2 are converted into A3 elements with electrodes . Subsequently, step (i) is performed to form a first conductor layer that electrically interconnects the electrodes of the elements A3, with the through holes 75 as conductive paths.

These steps can be carried out by the same procedures described in 1-8) and 1-9) of embodiment 1. For example, as illustrated in Figure 34 (3), an electrode 79 is formed on the surface of the first semiconductor 4 inside the through hole of the electrical insulating layer 71. Next, as illustrated in Figure 34 (4), a conductive adhesive 76 is applied to the electrode 79 inside the through hole 75, and a metal sheet 70 it is glued to the electrical insulator layer 71, to form a first conductor layer.

The production processes of the present invention described above can provide photovoltaic devices with high quality and high reliability, in which the spherical photovoltaic elements are firmly fixed at the predetermined positions within the recesses of a support and the first semiconductors and the layers of Second semiconductor of all the elements fixed to the support are electrically connected to a first conductor layer and a second conductor layer, respectively, reliably.

Of the embodiments of the production processes of the present invention described above, in embodiments 1 to 3, the photovoltaic elements A1 are mounted on the support before the exposed part of the first semiconductor and the electrode are formed. Therefore, in step (f), the elements can be arranged in the recesses of the support in any orientation. On the other hand, in embodiment 5 or 4, by arranging the elements A2 with the exposed part of the first semiconductor or the elements A3 with the electrode in the support, it is necessary to control the orientation of the elements in a particular orientation. Therefore, embodiments 1 to 3 have an advantage over embodiments 5 and 4 in which step (f) is simplified. However, embodiments 4 and 5 have an advantage in terms of quality control, that is, the characteristics of the elements can be checked before being mounted on the support.

Furthermore, in step (b), embodiments 1 and 2 have an advantage in that the second semiconductor layer can be removed without being obstructed by the electrical insulating layer, unlike embodiment 3 in which the layer of Second semiconductor inside the through hole of the electrical insulating layer is removed. On the other hand, in the embodiment 3, since the support is covered by the electrical insulating layer, the conditions for controlling the chemical attack improve.

In addition, in step (c), in embodiment 2, the electrode is formed before forming the electrical insulating layer. Therefore, when the applied conductive paste is subjected to a heat treatment by laser irradiation, decomposition products such as carbon can be dispersed, thereby coming into contact with the support and causing a short circuit. On the other hand, in embodiments 1 and 3, since the electrode is formed on the first semiconductor within the through hole of the electrical insulating layer, the decomposition products remain within the through hole and are not likely to cause a short circuit. Therefore, in order to avoid short circuit, it is necessary in embodiment 2 to control, for example, the conditions of laser irradiation and the state of application of the conductive paste more carefully than in embodiments 1 and 3.

In addition, in embodiment 4, since the characteristics of the elements with the electrode formed thereon can be checked previously, the elements can be selected more reliably than in embodiment 5. However, in embodiment 5, since the electrode is formed on the elements mounted on the support in step (c), there is an advantage that complicated stages are not necessary compared to embodiment 4 in which the electrode is formed on a large number of the elements that are fixed in controlled orientation.

As described above, since the respective embodiments have their own unique characteristics, they can be selected as appropriate depending on the individual production conditions of the photovoltaic devices.

Figure 35 illustrates a photovoltaic device according to the present invention. The photovoltaic device of Figure 35 is produced according to the first embodiment of the production process of the present invention. Since this device has the same configuration as in Figure 16 except that the second semiconductor layer has, on the surface, a conductive anti-reflection coating 9 50 to 100 nm thick comprising tin oxide oxidized with at least one of fluoride and antimony, the explanation of the configuration is omitted.

The photovoltaic device according to the present invention can be rationally produced with high quality by the respective embodiments of the production processes of the present invention.

The photovoltaic element used in the photovoltaic device of the present invention has the conductive anti-reflection coating on the surface of the second semiconductor layer. Therefore, the second semiconductor layer can be connected to the second conductor layer of the support, with the anti-reflection coating and the conductive adhesive interposed therein, with a low resistance and without a high temperature heat treatment. Since there is no need to expose the second conductor layer to high temperatures, even if the second conductor layer has a thin layer of silver suitable as a reflective mirror, there is no fear that the silver layer may discolor or be damaged by the heat treatment causing a deterioration of the reflectivity.

To electrically connect a second semiconductor layer that does not have any conductive anti-reflection coating to a second conductor layer with a low resistance, it is preferred to use a conductive paste of glass frit type, rather than a conductive paste of resin type, such as the conductive adhesive and apply a heat treatment at approximately 500 ° C. However, such a high temperature heat treatment causes damage, such as discoloration, to silver, thereby decreasing the function as a reflective mirror. The present inventors have experimentally discovered that, in the case of an element with a conductive anti-reflection coating, using a resin-like conductive paste and applying a heat treatment at 100 to 200 ° C, or using a conductive paste that includes a glass of Under melting point as a binder and by applying a heat treatment at 200 to 400 ° C, the second semiconductor layer can be electrically connected to the second conductor layer with a low resistance without discoloration of the silver. Although the reason is still unclear, it is probably due to the fact that the anti-reflection coating and the semiconductor layer, and the anti-reflection coating and the conductive paste, are connected to a low electrical resistance, with the anti-reflection coating acting as an electrode for the second semiconductor .

The photovoltaic device as described in the previous embodiments constitutes a unit of a solar cell module. This unit consists of a support of, for example, 170 mm x 54 mm and 1800 A3 elements with a diameter of approximately 1 mm mounted on the support, and has a nominal output power of approximately 1 W.

Although the present invention has been described in terms of the presently preferred embodiments, it should be understood that said description should not be construed as limiting.

Claims (27)

1. Production process of a photovoltaic device comprising: a plurality of substantially spherical photovoltaic elements (10, 20), each comprising: a first substantially spherical semiconductor (1); a second semiconductor layer (2) that covers the surface of the first semiconductor (1); a conductive antireflection coating (9) covering the surface of the second semiconductor layer (2), said antireflection coating (9) and said second semiconductor layer (2) having a common opening through which a part is exposed of the first semiconductor (1); and an electrode (5, 62, 67, 79, 97) formed on the exposed part (4, 14, 96) of the first semiconductor; a support (15, 25, 35) having a plurality of adjacent recesses (16, 26, 36) to cover said photovoltaic elements (10, 20) one by one on a front face thereof, each of the recesses ( 16, 26, 36) an inner face that functions as a reflecting mirror and an opening (17, 27, 37) in a lower part thereof, the opening (17, 27, 37) being smaller than each of said photovoltaic elements (10, 20), said support (15, 25, 35) serving as a second conductor layer that is electrically connected with the second semiconductor layers (2) of the respective photovoltaic elements (10, 20) arranged in said recesses ( 16, 26, 36), with said anti-reflection coating (9) interposed between said second semiconductor layers (2) and said support (15, 25, 35), each of said photovoltaic elements (10, 20) being fixed to each of said recesses (16, 26, 36) with a conductive adhesive (13, 51), so that the anti-reflection coating (9) thereof is in contact with an edge of said opening (17, 27, 37) of the recess (16, 26, 36) and that the exposed part (4, 14, 96) of the first semiconductor (1) protrudes through a rear face of the support ( 15, 25, 35); and an electrical insulating layer (38, 71, 91) and a first conductor layer (32, 70, 92) which are provided on the rear face of the support (15, 25, 35), so that said insulating layer electrical (38, 71, 91) isolate the support (15, 25, 35) of the first conductor layer (32, 70, 92), said electrical insulating layer (38, 71, 91) having a plurality of through holes (60, 68, 73, 75, 77, 93, 95), said first conductor layer (32, 70, 92) being electrically connected to said electrodes (5, 62, 67, 79, 97) of said photovoltaic elements ( 10, 20) through the through holes (60, 68, 73, 75, 77, 93, 95) or said electrical insulating layer (38, 71, 91), said procedure comprising the following steps:

(to)

providing a plurality of substantially spherical photovoltaic elements A1, each comprising a first substantially spherical semiconductor (1) and a second semiconductor layer (2) that covers the entire surface of the first semiconductor (1), and forms an anti-reflection coating (9) conductor on the surface of each of said second semiconductor layers (2);

(b)

forming an opening in the second semiconductor layer (2) of each of said photovoltaic elements A1 to expose a part (4, 14, 96) of the first semiconductor (1), to prepare photovoltaic elements A2, in which a part of said anti-reflection coating (9) is removed together with the second semiconductor layer (2) to form said opening;

(C)

forming an electrode (5, 62, 67, 79, 97) on the exposed part (4, 14, 96) of the first semiconductor (1) of each of said photovoltaic elements A2, to prepare photovoltaic elements A3;

(d)

providing said support (15, 25, 35);

(and)

apply a conductive adhesive (13, 51) to a periphery of each of the openings (17, 27, 37) of said support (15, 25, 35);

(F)

disposing said photovoltaic elements A1, A2 or A3 in the recesses (16, 26, 36) of said support (15, 25, 35) so that the second semiconductor layers (2) are in contact with the edges of the openings ( 17, 27, 37) of said support, and connecting said second semiconductor layers (2) to said support (15, 25, 35) electrically and physically with said conductive adhesive (13, 51);

(g)

forming an electrical insulating layer (38, 71, 91) on the rear face of said support (15, 25, 35);

(h)

forming through holes (60, 68, 73, 75, 77, 93, 95) in said electrical insulator layer (38, 71, 91), said through holes serving as conductive paths for interconnecting electrodes (5, 62, 67 , 79, 97) of said photovoltaic elements A3; Y

(i)

forming a first conductor layer (32, 70, 92) on said electrical insulator layer (38, 71, 91), said first conductor layer electrically interconnecting the electrodes (5, 62, 67, 79, 97) that are exposed within said through holes (60, 68, 73, 75, 77, 93, 95),

wherein said stage (e) is performed before said stage (f), and said stage (f) is performed before said stage (g).

2.

Production method of a photovoltaic device according to claim 1, wherein said steps (a) and (d) are carried out, and then said steps (e), (f), (b), (g) are performed in this order ), (h), (c), e (i).

3.

Production method of a photovoltaic device according to claim 1, wherein said steps (a) and (d) are carried out, and then said steps (e), (f), (b), (c) ), (g), (h), e (i).

Four.

Production process of a photovoltaic device according to claim 1, wherein said steps (a) and (d) are carried out, and then said steps (e), (f), (g), (h) are performed in this order ), (b), (c), e (i).

5.

Production method of a photovoltaic device according to claim 1, wherein said steps (a), (b), (c), and (d) are performed, and then said steps (e) are carried out in this order, ( f), (g), (h), e (i).

6.

Production method of a photovoltaic device according to claim 1, wherein said steps (a), (b), and (d) are performed, and then said steps (e), (f), ( g), (h), (c), e (i).

7.

Production process of a photovoltaic device according to claim 1, wherein said photovoltaic elements (10, 20) are mainly composed of silicon.

8.

Method of producing a photovoltaic device according to claim 1, wherein said anti-reflection coating (9) comprises tin oxide doped with at least one of fluorine and antimony.

9.

Production method of a photovoltaic device according to claim 8, wherein said anti-reflection coating (9) has a thickness between 50 and 100 nm.

10.

Production method of a photovoltaic device according to claim 1, wherein said step (e) comprises the following steps:

applying said conductive adhesive (51) on pin tips (126) (124) that are slightly larger than the openings (17) of said support (15); Y transferring said conductive adhesive (51) applied to said tips (126) to the peripheries of said openings (17), inserting said tips into recesses (16) of said support (15) from the front face of said support and placing said tips (126) in contact with the peripheries of said openings (17), so that the centers of said tips and said openings are aligned. 11. Production method of a photovoltaic device according to claim 1, wherein said step (e) comprises the following steps: placing a metal mask on the rear face of said support (15), said metal mask presenting a plurality of groups of openings (21) corresponding to the openings (17) of said support (15), each group of openings (21) consisting in a plurality of openings (22) that are disposed along an opening edge of each opening (17), each opening (22) being shaped such that it covers an area that extends from an outer part of the opening edge from the opening (17) to an inner part thereof; and print the conductive adhesive (13) on said support (15) through the openings (22) of said metal mask, so that the conductive adhesive (13) is applied to said support (15) in a plurality of locations at along the opening edge of each of said openings (17), so that it covers an area that extends from a periphery of each opening (17) on the rear face of the support (15) to a periphery of the opening (17) on the front face thereof.

12.

Method of producing a photovoltaic device according to claim 1, wherein said step (b) comprises removing a part of the second semiconductor layer (2) of each of said photovoltaic elements A1 by chemical attack, to form said opening.

13.

Method of producing a photovoltaic device according to claim 12, wherein said step (b) comprises, before said chemical attack stage, the step of previously removing the part of the second semiconductor layer (2) to be subjected a chemical attack by brushing or sandblasting.

14.

Method of producing a photovoltaic device according to claim 5, wherein said step (b) comprises the step of cutting a part of each of said photovoltaic elements A1, so that the opening of the second semiconductor layer (2) thereof is substantially flush with the exposed part (4) of the first semiconductor (1).

fifteen.

Production method of a photovoltaic device according to claim 1, wherein said step (c) comprises the following steps:

applying a conductive paste (61) to the exposed part (14) of the first semiconductor (1) of each of said photovoltaic elements A2; Y applying a heat treatment to the conductive paste (61) applied by laser irradiation, to form said electrode (62). 16. Production method of a photovoltaic device according to claim 5, wherein said step (b) comprises the following steps: providing a support element having a plurality of recesses in a predetermined pattern to receive said photovoltaic elements A1 at a predetermined depth; disposing the photovoltaic elements A1 in the recesses of said support element; applying a molten wax to said support element and cooling it, to fix said photovoltaic elements A1 to the recesses of said support element with the solidified wax; Y pressing a rotating grinder on the photovoltaic elements A1 fixed to said support element to rectify the surfaces of the photovoltaic elements A1, to form the exposed parts (4) of the first semiconductors (1), and said stage (c) comprises the following stages: apply a conductive paste to the exposed parts (4) of the first semiconductors (1); and heating said support element at a temperature between 400 and 800 ° C, to remove said wax and form the electrodes (5) on the exposed parts (4) of the first semiconductors (1). 17. Production method of a photovoltaic device according to claim 5, wherein each of said photovoltaic elements A3 is configured so that the electrode (5) or its surroundings (6, 7) is more magnetic than other parts, and said step (f) comprises the step of applying a magnetic field to said photovoltaic elements A3 from a predetermined direction, to align said electrodes (5) or the vicinity thereof (6, 7) in a predetermined orientation. 18. Production method of a photovoltaic device according to claim 1, wherein said step (g) comprises the step of joining a semi-cured electrical insulating layer (71), which comprises an insulating sheet composed primarily of a thermosetting resin, to the rear face of said pressurized support (15), and said stage (i) comprises the following stages: bond a conductive metal sheet (70) to the semi-cured electrical insulating layer (71) under pressure; Y curing the semi-cured electrical insulating layer (71) by heat treatment, to fix said conductive metal sheet (70) to the electrical insulating layer (71).

19.

Production method of a photovoltaic device according to claim 1, wherein said step (i) comprises the step of applying a conductive paste (31) to said electrical insulating layer (38), so as to interconnect the electrodes (62) of the photovoltaic elements A3 that are exposed within the through holes of said electrical insulating layer (38) and heating it for solidification, to form the first conductor layer (32).

twenty.

Production method of a photovoltaic device according to claim 1, wherein said step (i) comprises the following steps:

fill the through holes (60) of said electrical insulating layer (38) with a conductive paste (63), so that they come into contact with the electrodes (62) of the photovoltaic elements A3; joining a conductive metal sheet (70) to said electrical insulating layer (38); and heating and solidifying said conductive paste (63), to electrically connect said conductive paste (63) to said conductive metal sheet (70). 21. Production method of a photovoltaic device according to claim 3, wherein said steps (g) to (i) comprise the following steps: joining an electrical insulating layer (91) and a conductive metal sheet (92) to the rear face of said support (15), so that the electrical insulating layer (91) separates said conductive metal sheet (92) from said support (fifteen); forming through holes (93) in the electrical insulating layer (91) and the conductive metal sheet (92) attached to said support (15) to expose the electrodes (67) of said photovoltaic elements A3 within said through holes (93) ); Y fill with a conductive paste (94) said through holes (93) to electrically connect said electrodes (67) to said conductive metal sheet (92), to form said first conductor layer. 22. Production method of a photovoltaic device according to claim 5, wherein said steps (g) to (i) comprise the following steps: joining an electrical insulating layer (91) and a conductive metal sheet (92) to the rear face of said support (15), so that the electrical insulating layer (91) separates said conductive metal sheet (92) from said support (fifteen); forming through holes (77) in the electrical insulating layer (91) and the conductive metal sheet (92) attached to said support (15) to expose the electrodes (5) of said photovoltaic elements A3 within said through holes (77 ); Y fill with a conductive paste (78) said through holes (77) to electrically connect said electrodes (5) to said conductive metal sheet (92), to form said first conductor layer.

2. 3.

Method of producing a photovoltaic device according to claim 21, wherein said step of joining the electrical insulating layer (91) and the conductive metal sheet (92) to the rear face of said support (15) comprises the step of joining a composite sheet (90), which includes a conductive metal sheet (92) and an electrical insulating layer (91) laminated to one side of the conductive metal sheet (92), to the rear face of the support (15) of so that the electrical insulating layer (91) faces the support (15).

24.

Method of producing a photovoltaic device according to claim 22, wherein said step of joining the electrical insulating layer (91) and the conductive metal sheet (92) to the rear face of said support (15) comprises the step of joining a composite sheet (90), which includes a conductive metal sheet (92) and an electrical insulating layer (91) laminated to one side of the conductive metal sheet (92), to the rear face of the support (15) of so that the electrical insulating layer (91) faces the support (15).

25.

Method of producing a photovoltaic device according to claim 23, wherein said step of joining the composite sheet (90) comprises the following steps:

applying an electrically insulating adhesive to the back face of said support (15), to form a layer of adhesive (69); Y bonding the electrical insulating layer (91) of said composite sheet (90) to said adhesive layer (69) of the support (15). 26. Production method of a photovoltaic device according to claim 24, wherein said step of joining the composite sheet (90) comprises the following steps: applying an electrically insulating adhesive to the back face of said support (15), to form a layer of adhesive (69); Y bonding the electrical insulating layer (91) of said composite sheet (90) to said adhesive layer (69) of the support (15). 27. Photovoltaic device comprising: a plurality of substantially spherical photovoltaic elements, each comprising: a first substantially spherical semiconductor (1); a second semiconductor layer (2) that covers the surface of the first semiconductor (1); a conductive antireflection coating (9) covering the surface of the second semiconductor layer (2), said antireflection coating (9) and said second semiconductor layer (2) having a common opening, through which a part of the first semiconductor (1); and an electrode (62) formed on the exposed part (14) of the first semiconductor (1); 5 a support (15) having a plurality of adjacent recesses to cover said photovoltaic elements one by one on a front face thereof, each of the recesses presenting an inner face that functions as a reflecting mirror and an opening in a lower part thereof, the opening being smaller than each of said photovoltaic elements, said support (15) serving as a second conductor layer that is electrically connected with the second semiconductor layers (2) of the respective photovoltaic elements 10 arranged in said recesses; each of said photovoltaic elements being fixed to each of said recesses with a conductive adhesive (51) so that the anti-reflection coating (9) thereof is in contact with an edge of said opening of the recess and that the exposed part (14) of the first semiconductor (1) protrudes through a rear face of the support 15 (15); an electrical insulating layer (71) and a first conductor layer (70) which are provided on the rear face of the support (15) so that said electrical insulating layer (71) insulates the support (15) from the layer of first conductor (70), said electrical insulating layer (71) having a plurality of through holes, said being 20 first conductor layer (70) electrically connected to said electrodes (62) of said photovoltaic elements by means of the through holes of said electrical insulating layer (71); and characterized because said anti-reflection coating (9) is interposed between said second semiconductor layers (2) and said support (15).