JP2005197537A - Integrated thin film solar battery and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the increase of sheet resistance generated when the film thickness of a second electrode film is locally made thin and the deterioration of converting efficiency caused by this increase. <P>SOLUTION: This integrated thin film solar battery is provided with solar battery units 11A and 11B where a first electrode film 2 divided by a first dividing groove 13, a semiconductor film 5 divided by a second dividing groove 16 and a second electrode film 7 divided by a third dividing groove 18 are successively laminated with almost equal film thicknesses on the surface of an insulating substrate 1. The second electrode film 7 of the solar battery unit 11A is brought into contact with the first electrode film 2 of the solar battery unit 11B, and the adjacent solar battery units are serially connected. The first dividing groove 13 with a trapezoidal shape cross section is formed toward the insulating substrate 1, and the front laminate 7a of the second electrode film 7 formed corresponding to the surface of the insulating substrate 1 is connected to the second electrode film 7 of a connecting part T on the first electrode film 2 brought into contact by the third dividing groove 18 through the inclined laminate 7b of the second electrode film 7 formed through a semiconductor film 5 on the inclined face 13b of the first dividing groove 13. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an integrated thin film solar cell and a method for manufacturing the same, and more particularly to a compound semiconductor solar cell module using a chalcopyrite type compound semiconductor thin film as a light absorbing layer and a method for manufacturing the same.

  As an example of a conventional integrated thin film solar cell, a light-absorbing layer is a I-III-VI2 type chalcopyrite compound semiconductor composed of group I, group III, and group VI elements, specifically, CuInSe2 (CIS). Or what is using the thin film solar cell which is Cu (In, Ga) Se2 (CIGS) as an integrated structure is disclosed by patent document 1, for example.

  7 to 8 show a conventional integrated thin film solar cell described in Patent Document 1, and FIG. 7 shows a cross-sectional structure of the solar cell unit. As shown in FIG. 7, on the insulating substrate 1, the first electrode film 2, the semiconductor film 5, and the second electrode film 7 are formed in this order to constitute solar cell units 11A and 11B. The first electrode film 2 is divided into strips by the first dividing grooves 3, the semiconductor film 5 is divided into strips by the second dividing grooves 6 having a rectangular cross section, and the second electrode film 7 is a third having a rectangular section. It is divided into strips by the dividing groove 8. Further, in the portion of the second dividing groove 6 that divides the semiconductor film 5, the first electrode film 2 of the left solar cell unit 11A and the second electrode film 7 of the right solar cell unit 11B are in contact with each other. Adjacent solar cell units 11A and 11B are connected in series.

  FIGS. 8A to 8G are cross-sectional views showing a method for manufacturing the integrated thin film solar cell, respectively. As shown in FIG. 8A, an insulating substrate 1 made of, for example, soda lime glass is prepared. As shown in FIG. 8B, the first electrode film 2 is formed on the insulating substrate 1. As the first electrode film 2, for example, a Mo film is laminated by a sputtering method. Next, as shown in FIG. 8 (c), the first divided grooves 3 having a rectangular cross section are formed in the first electrode film 2 by removing them in a line shape perpendicular to the series direction of the solar cell units 11A and 11B. One electrode film 2 is separated into strips. The first dividing groove 3 is formed, for example, by laser patterning in which a Mo film laminated as the first electrode film 2 is irradiated with laser light to evaporate.

  As shown in FIG. 8D, the semiconductor film 5 is formed on the surface of the first electrode film 2 including the first dividing groove 3. The semiconductor film 5 is composed of, for example, a light absorption layer made of a CIGS compound semiconductor thin film, a CdS layer as a buffer layer, and a ZnO layer as a window layer. The thickness of the semiconductor film 5 is about 2 μm. Next, as shown in FIG. 8 (e), the semiconductor film 5 is displaced by a predetermined distance L 1 from the first divided groove 2 toward the adjacent right solar cell unit 11 B, and parallel to the first divided groove 2. By deleting the surface of the first electrode film 2 in a line shape, the second divided groove 6 having a rectangular cross section is formed, and thereby the semiconductor film 5 is differentiated into a strip shape. For example, a mechanical scribing method is employed to form the second divided groove 6.

  As shown in FIG. 8F, the second electrode film 7 is formed on the surface of the semiconductor film 5 including the second dividing groove 6. As the second electrode film 7, for example, an ITO transparent conductive film is formed by a sputtering method. Next, as shown in FIG. 8G, the semiconductor film 5 and the second electrode film 7 are simultaneously given to the right solar cell unit 11 </ b> B side parallel to the second divided groove 6 and adjacent to the second divided groove 6. The third divided groove 8 having a rectangular cross section is formed by shifting the position L2 and removing it in a line. For example, a mechanical scribing method is employed to form the third dividing groove 8.

In FIG. 7, the first dividing groove 3, the second dividing groove 6, and the third dividing groove 8 are formed in this order with a predetermined distance L1, L2, and do not overlap each other. As shown, a structure in which a part of the first to third divided grooves 3, 6, 8 overlap is also possible. That is, in FIG. 9, the first divided groove 3 and the second divided groove 6 partially overlap, and the second divided groove 6 and the third divided groove 8 partially overlap, but the first divided groove 3 and the third divided groove 8 has a structure that does not overlap each other.
JP 2001-320071 A (page 6, FIG. 1)

  However, in the conventional configuration, when the second electrode film 7 is formed by the sputtering method, the second electrode film 7 is formed on a bottom portion parallel to the insulating substrate 1 in a portion corresponding to the second dividing groove 6. The film thickness t1 of the second electrode film groove bottom surface 7a is substantially the same as the surface of the semiconductor film 5, but the film thickness t2 of the second electrode film groove side surface 7b on the side surface of the second divided groove 6 is thin. It became less than 1/10 of the film thickness t1 of the two-electrode film groove bottom surface 7b. In the sputtering method, the particles sputtered from the target to the insulating substrate 1 are mostly particles flying in the vertical direction with respect to the insulating substrate 1, and the number of particles flying in the horizontal direction is small. The film thickness t1 of the second electrode film groove side surface 7b laminated on the side surface of the second dividing groove 6 perpendicular to the surface of the first surface is less than 1/10. For this reason, the sheet resistance of the second electrode film groove side surface 7b becomes 10 times or more the sheet resistance of the second electrode film groove bottom surface 7a, and the series resistance increases.

For example, when an ITO film which is a transparent conductive film is laminated as the second electrode film 7 with a film thickness of 300 nm, the ITO film formed on the second electrode film groove bottom surface 7a parallel to the insulating substrate 1 of the semiconductor film 5 is formed. Although the sheet resistance was 10Ω / □ or less, the sheet resistance of the ITO film (second electrode film 31 on the semiconductor film cross section) formed on the second electrode film groove side surface 7b is 100Ω / □ or more. Conceivable. As a result, the conversion efficiency of an integrated thin-film solar cell is as low as 12%, the series resistance was 1.5 [Omega · cm ^2, would greatly exceed 0.5 .OMEGA · cm ² is desirable series resistance as a solar cell.

Here, in order to make the series resistance 0.5Ω · cm ² or less, when the second electrode film 7 was laminated by about 600 nm, the exchange efficiency of the integrated thin film solar cell was improved to 13.3%. However, there has been a problem that the time required to increase the thickness of the second electrode film 7 becomes longer. Further, in the case of a substrate type solar cell using a transparent conductive film such as an ITO film as the second electrode film 7 in this way, the transmittance of the transparent conductive film is reduced by increasing the film thickness of the second electrode film 7. As a solar cell characteristic, there is a problem that conversion efficiency decreases due to a decrease in short-circuit current. For example, the ITO film has a transmittance of 85% when the film thickness is 300 nm, but decreases to 80% when the film thickness is 600 nm.

  The present invention solves the above-described conventional problems, and an integrated thin film solar cell that can prevent an increase in sheet resistance caused by a locally thin film thickness of the second electrode film and a decrease in conversion efficiency caused thereby. And it aims at providing the manufacturing method.

  The integrated thin-film solar cell according to claim 1 of the present invention includes a first electrode film divided by a first dividing groove, a semiconductor film divided by a second dividing groove on a surface of an insulating substrate, A second electrode film divided by the three-divided grooves is provided with a solar cell unit that is sequentially laminated with a substantially uniform film thickness in a direction perpendicular to the surface of the insulating substrate, and the second electrode of one solar cell unit An integrated thin-film solar cell in which the first electrode film of the film and the other solar cell unit are in contact with each other and adjacent solar cell units are connected in series, wherein the first divided groove is an isosceles trapezoidal cross section, A second layer formed corresponding to the surface of the insulating substrate by the inclined laminated portion of the second electrode film formed over the insulating substrate and formed on the inclined surface of the first dividing groove via the semiconductor film. On the first electrode film in contact with the surface lamination portion of the electrode film and the third dividing groove Those configured to connect the second electrode layer of the connecting portion.

  The integrated thin-film solar cell according to claim 2, wherein the thickness of the inclined forming portion of the second electrode film is the same as the thickness of the surface laminated portion of the second electrode film formed on the surface of the insulating substrate via the semiconductor film. Of 1/2 or more.

In the integrated thin-film solar cell according to claim 3, the inclination angle θ on the groove side of the inclined surface of the first divided groove with respect to the surface of the insulating substrate is set to 0 ° <θ ≦ 60 °.
In the integrated thin-film solar cell according to claim 4, the depth of the first dividing groove is in the range of the thickness of the semiconductor film ± the thickness of the second electrode film.

  The integrated thin film solar cell according to claim 5, wherein the second divided groove is formed around an edge of the first divided groove on the other solar cell unit side, and the third divided groove is formed at the bottom of the second divided groove. Thus, the second solar cell unit is formed on the other solar cell unit side leaving the connection portion of the second electrode film in contact with the first electrode plate of the other solar cell unit.

  According to a sixth aspect of the present invention, there is provided a method of manufacturing the integrated thin film solar cell, comprising: a first electrode film divided by the first dividing groove; a semiconductor film divided by the second dividing groove; A solar cell unit in which the second electrode film divided by the dividing groove is sequentially laminated with a substantially uniform film thickness in a direction perpendicular to the surface of the insulating substrate, and the first electrode film of one solar cell unit And the second electrode film of the other solar cell unit are in contact with each other, and adjacent solar cell units are connected in series, and the insulating substrate has at least one solar cell unit side. A slope forming groove having a trapezoidal cross section with an inclined surface is formed in parallel with the first to third divided grooves, a first divided groove is formed in the first electrode film above the slope forming groove, and the first Two split grooves are formed on the other solar cell unit of the inclined surface forming grooves. The third dividing groove is formed on the edge of the other solar cell unit on the other edge of the slope forming groove on the other solar cell unit side, and the other is formed on the first electrode surface. The second electrode formed on the solar cell unit side and corresponding to the surface of the insulating substrate by the inclined stacked portion of the second electrode film formed on the inclined surface of the inclined surface forming groove via the semiconductor film The surface laminated portion of the film is connected to the connection portion of the second electrode film on the first electrode film that is in contact with the third dividing groove.

The manufacturing method of the integrated thin-film solar cell according to claim 7 is such that the thickness of the inclined laminated portion of the second electrode film is ½ or more of the thickness of the surface laminated portion of the second electrode film.
The integrated thin-film solar cell according to claim 8 is such that the inclination angle γ on the groove side of the inclined surface of the inclined surface forming groove with respect to the surface of the insulating substrate is 0 ° <γ ≦ 60 °.

In the integrated thin-film solar cell according to claim 9, the depth of the slope forming groove is in the range of the film thickness of the semiconductor film ± the film thickness of the second electrode film.
The method of manufacturing an integrated thin-film solar cell according to claim 10 includes: a first electrode film divided by a first dividing groove; a semiconductor film divided by a second dividing groove; The second electrode film divided by the dividing groove includes a solar cell unit that is sequentially laminated on the surface of the insulating substrate, and the first electrode film of one solar cell unit and the second electrode of the other solar cell unit When manufacturing an integrated thin film solar cell in which adjacent solar cell units are in series contact with each other in contact with a film, a first dividing groove is formed on an insulating substrate on which the first electrode film is laminated, A semiconductor film having a uniform film thickness is formed on the first electrode film and the first dividing groove in a direction perpendicular to the surface of the insulating substrate, and then a second dividing groove is formed in the semiconductor film. Direction perpendicular to the surface of the insulating substrate on the two-divided groove A second electrode film having a uniform film thickness is formed, and the second electrode film and the semiconductor film 5 are deleted up to the surface of the first electrode film at a position not overlapping the first division groove to form a third division groove. In addition, the inclination angle γ on the removal side of the inclined surface of the second divided groove with respect to the surface of the insulating substrate is set to 0 ° <γ ≦ 60 °.

In the manufacturing method of the integrated thin-film solar cell according to claim 11, the step of forming the first dividing groove is performed by one of microblasting and fine processing by atmospheric pressure plasma.
The method of manufacturing an integrated thin-film solar cell according to claim 12 includes: a first electrode film divided by a first dividing groove; a semiconductor film divided by a second dividing groove; It has a solar cell unit in which the second electrode film divided by the dividing groove is sequentially laminated, and the first electrode film of one solar cell unit and the second electrode film of the other solar cell unit are in contact with each other and adjacent to each other. In manufacturing an integrated thin film solar cell in which solar cell units are connected in series, a slope forming groove having a trapezoidal cross section is formed on the surface of the insulating substrate 1, and the insulating substrate is formed on the insulating substrate and the slope forming groove. Forming a first electrode film having a uniform film thickness in a direction perpendicular to the surface of the first electrode film, forming a first dividing groove in the first electrode film formed on the inclined surface forming groove, and forming the first electrode film and the first dividing film into Evenly in the direction perpendicular to the surface of the insulating substrate on the groove A semiconductor film having a thickness is formed, a second divided groove is formed corresponding to the other solar cell unit side edge of the inclined surface forming groove, and the surface of the insulating substrate is formed on the semiconductor film and the second divided groove. Forming a second electrode film having a uniform thickness in a vertical direction, being displaced from the inclined surface forming groove toward the other solar cell unit, and forming a third dividing groove in the second electrode film; The inclination angle γ on the deletion side of the inclined surface of the second divided groove with respect to the surface of the surface is such that 0 ° <γ ≦ 60 °.

  In the method of manufacturing an integrated thin film solar cell according to claim 13, the slope forming groove is formed by microblasting.

  According to the first or tenth aspect of the present invention, since the first divided groove having a trapezoidal cross section extending to the insulating substrate is formed in the second electrode film, the inclination of the second divided film corresponding to the inclined surface of the first divided groove. Since the thickness of the laminated portion is not a conventional vertical surface but an inclined surface, the thickness of the inclined laminated portion of the second electrode film can be sufficiently increased. Accordingly, it is an object to provide an integrated thin film solar cell in which the second electrode film extending from the surface of the insulating substrate to the first electrode film is locally thinned so that the sheet resistance does not increase and the conversion efficiency is unlikely to decrease. Can do.

  According to the second or third aspect of the invention, the second electrode film is formed by setting the thickness of the inclined laminated portion of the second divided film to ½ or more of the thickness of the surface laminated portion of the second divided film. The sheet resistance of the inclined laminated portion was less than 20Ω / □, and was suppressed to less than twice the sheet resistance of the second electrode film of the front laminated portion. Therefore, compared to the conventional case where the entire thickness of the second electrode film is increased, the entire thickness of the second electrode film can be made thinner than that of the conventional example, for example, about 300 nm. The work time required for the deposition of can also be shortened. In the case of a substrate type solar cell using a transparent conductive film as the second electrode film, the thickness of the second electrode film can be reduced, so that the transmittance does not decrease and the short-circuit current increases as solar cell characteristics. Thus, the conversion efficiency can be improved to, for example, 14.5%.

  According to the invention of claim 6 or 12, since the slope forming groove having the trapezoidal cross section formed in the insulating substrate is formed, the film thickness of the inclined laminated portion of the second divided film corresponding to the inclined surface of the slope forming groove. Is an inclined surface instead of a conventional vertical surface, and thus the thickness of the inclined laminated portion of the second electrode film can be sufficiently increased. Accordingly, it is an object to provide an integrated thin film solar cell in which the second electrode film extending from the surface of the insulating substrate to the first electrode film is locally thinned so that the sheet resistance does not increase and the conversion efficiency is unlikely to decrease. Can do.

  According to the invention of claim 7 or 8, the second electrode film is formed by setting the film thickness of the inclined laminated portion of the second divided film to ½ or more of the film thickness of the surface laminated portion of the second divided film. The sheet resistance of the inclined laminated portion was less than 20Ω / □, and was suppressed to less than twice the sheet resistance of the second electrode film of the front laminated portion. Therefore, compared to the conventional case where the entire thickness of the second electrode film is increased, the entire thickness of the second electrode film can be made thinner than that of the conventional example, for example, about 300 nm. The work time required for the deposition of can also be shortened. In the case of a substrate type solar cell using a transparent conductive film as the second electrode film, the thickness of the second electrode film can be reduced, so that the transmittance does not decrease and the short-circuit current increases as solar cell characteristics. Thus, the conversion efficiency can be improved to, for example, 14.5%.

[Embodiment 1]
Hereinafter, an integrated thin film solar cell and a manufacturing method thereof according to the present invention will be described with reference to FIGS. The same members as those in the conventional example will be described with the same reference numerals.

FIG. 1 is a cross-sectional view of a series connection portion of a solar cell unit of an integrated thin film solar cell, and FIG. 2 is a partially enlarged view of the series connection portion.
On the insulating substrate 1, a first electrode film 2, a semiconductor film 5, and a second electrode film 7 are formed in this order to constitute solar cell units 11A and 11B. The first electrode film 2 is divided into strips by the first dividing grooves 13, the semiconductor film 5 is divided into strips by the second dividing grooves 16 having a rectangular cross section, and the second electrode film 7 is a third having a rectangular section. It is divided into strips by the dividing groove 18. Further, in the portion of the second dividing groove 6 that divides the semiconductor film 5, the first electrode film 2 of the left solar cell unit 11A and the second electrode film 7 of the right solar cell unit 11B are in contact with each other. Adjacent solar cell units 11A and 11B are connected in series.

  The first division grooves 13 formed in the first electrode film 2 are formed so as to reach the insulating substrate 1 with a width of 10 to 200 μm. The first dividing groove 13 has a trapezoidal cross section composed of a bottom surface 13a and left and right inclined surfaces 13b, penetrates the first electrode film 2 having a film thickness: d1 = 0.5 to 2 μm, and further has a depth from the surface of the insulating substrate 1. : The insulating substrate 1 is removed up to x, and the inclination angle of the inclined surface 13b with respect to the surface of the insulating substrate 1 is set in the range of 0 ° to 60 °.

  The second dividing groove 16 has a rectangular cross section, and a part of the second dividing groove 16 overlaps the right slope 13 b of the first dividing groove 13 with respect to the semiconductor film 5 stacked on the surface of the first electrode film 2 including the first dividing groove 13. And a semiconductor film 5 stacked above the right slope 13b of the second dividing groove 16 and a semiconductor film 5 stacked above the first electrode film 2 of the right solar cell unit 11B. The surface of the first electrode film 2 is deleted.

The third dividing groove 18 has a rectangular cross section, and a part of the right side is formed in parallel with each other at a position where it overlaps the second dividing groove 16, and the semiconductor film 5 and the second electrode film 7 stacked in the second dividing groove 16 are formed. It has been deleted.
The semiconductor film 5 is laminated on the front laminated portion 5 a laminated on the surface of the first electrode film 2, the inclined laminated portion 5 b laminated on the slope 13 of the first divided groove 13, and the bottom surface 13 a of the first divided groove 13. The bottom laminated portion 5c is laminated so that the film thickness in the vertical direction is substantially uniform except for the deleted portion by the second dividing groove 16.

  The second electrode film 7 includes a surface laminated portion 7 a laminated on the surface laminated portion 5 a of the semiconductor film 5, an inclined laminated portion 7 b laminated on the inclined laminated portion 5 b, and the right side exposed by the second dividing groove 16. The first electrode film 2 of the solar cell unit 11B and the bottom laminated portion 7c laminated on the bottom laminated portion 5c. And the surface lamination | stacking part 7a, the inclination lamination | stacking part 7b, and the bottom lamination | stacking part 7c are each laminated | stacked so that the film thickness of the orthogonal | vertical direction in a figure may become substantially equal. Since the inclined stacked portion 5b of the semiconductor film 5 and the inclined stacked portion 7b of the second electrode film 7 are parallel to the inclined surface 13b of the first dividing groove 13, the inclined stacked portion 7b perpendicular to the inclined surface 13b. The film thickness d4 is set to be equal to or greater than 1/2 of the film thickness d3 of the front laminated portion 7a. That is, here, the inclination angle θ of the left and right inclined surfaces 13b of the first dividing groove 13 is represented by d4 = d3 × cos θ ≧ d3 × 1/2, and θ = 0 ° to 60 °.

  Here, the film thickness of the first electrode film 2: d1 = 0.2 to 2 μm, the film thickness of the surface laminated portion 4a of the semiconductor film 5: d2 = 1 to 5 μm, the surface laminated portion 7a of the second electrode film 7 Film thickness: d3 = 0.1 to 1 μm.

  Here, the third dividing groove 18 partially overlaps the second dividing groove 16 at a position in the vertical direction, but it may not overlap. The third dividing groove 18 is formed so as not to overlap the first dividing groove 13. This is because when the third divided groove 18 and the first divided groove 13 overlap in the vertical direction, the connection portion T of the second electrode film 7 stacked on the first electrode film 2 is lost by the third divided groove 18. Because.

  Here, the depth of the first dividing groove 13 is x + d1, and the semiconductor film 5 is formed to have a film thickness x + d1≈d2 that is substantially the same as the film thickness d2. This is because when the depth of the first dividing groove 13: x + d1 and the film thickness of the semiconductor film 5: d2 are greatly different, the semiconductor film 5 is deleted up to the surface of the first electrode film 2 and the second dividing groove 16 is formed. This is because a vertical step portion is sometimes formed on the surface of the semiconductor film 2 and a thin film portion is formed on the second electrode film 7 to increase the sheet resistance. Here, the allowable range of the vertical step portion is a range (± d3) of increase / decrease of the thickness of the second electrode film 7: d3.

Therefore, d2−d3 ≦ x + d1 ≦ d2 + d3.
Next, a method for manufacturing the integrated thin film solar cell will be described with reference to FIGS.
As shown in FIG. 3A, an insulating substrate 1 made of, for example, soda lime glass is prepared. As shown in FIG. 3B, the first electrode film 2 is laminated on the insulating substrate 1. As the first electrode film 2, for example, a Mo film which is a metal film is formed by a sputtering method.

  As shown in FIG. 3 (c), the first dividing groove 13 is insulated from the first electrode film 2 in the first electrode film 2 in a direction perpendicular to the series direction of the solar cell units 11 A and 11 B of the integrated thin film solar cell. It extends to the conductive substrate 1 and is formed in a line shape. Here, the width of the first dividing groove 13 is 10 to 200 μm.

  As shown in FIG. 3D, the semiconductor film 5 is laminated on the first electrode film 2 and the first dividing groove 13. The semiconductor film 5 includes, for example, a light absorption layer, a buffer layer, and a window layer. A CIS compound semiconductor thin film is formed as a light absorption layer by a sputtering method or a multi-source deposition method, and a CdS film is deposited as a buffer layer by a CBD method. A ZnO film is formed by sputtering as a layer. Here, the semiconductor film 5 includes an I-III-VI group compound semiconductor, and the Group I element constituting the I-III-VI group compound semiconductor includes at least one of Cu and Ag. Furthermore, the group III element constituting the I-III-VI group compound semiconductor contains at least one of Al, In or Ga, and further the group VI constituting the group I-III-VI compound semiconductor The element contains at least one of Se and S.

  As shown in FIG. 3E, the second dividing groove 16 is formed in the semiconductor film 5 in a line shape parallel to the first dividing groove 3. The second dividing groove 16 is formed by a mechanical scribe method. The position of the second dividing groove 16 is 10 to 200 μm wide with the right end of the first dividing groove 13 as the center.

  As shown in FIG. 3 (f), the second electrode film 7 is laminated on the semiconductor film 5 and the second dividing groove 16. As the second electrode film 7, for example, an ITO film as a transparent conductive film is formed by a sputtering method. The second electrode film 7 may be a transparent conductive film containing at least one of ITO, ZnO, and SnO2. In this sputtering method, most of the particles sputtered from the target onto the insulating substrate 1 are particles flying in the vertical direction with respect to the insulating substrate 1 and few particles flying in the horizontal direction. For this reason, although it is laminated | stacked with a uniform film thickness in the direction perpendicular | vertical to the surface of the insulated substrate 1, a film thickness becomes thin, so that it becomes an inclined surface with a large inclination angle, or a perpendicular | vertical surface.

  As shown in FIG. 3G, the third dividing groove 18 is formed in a line shape in parallel with the second dividing groove 16 in the semiconductor film 5 and the second electrode film 7. The third dividing groove 18 may divide only the second electrode film 7 at a position not overlapping the second dividing groove 16. The third dividing groove 18 is formed by a mechanical scribing method.

  In the above manufacturing method, as a means for forming the first divided groove 13, fine processing by atmospheric pressure plasma or microblast processing is particularly effective because the processing speed is high. In microfabrication using atmospheric pressure plasma, a He / SF6 mixed gas is allowed to flow between parallel plate electrodes facing each other with a gap of several tens of μm in width, and an electric field is applied between the electrodes. The first electrode film 2 and the insulating substrate 1 are simultaneously etched by generating a shaped plasma and bringing the plasma close to form the first divided grooves 13. At this time, when Mo is used as the first electrode film 2, Mo becomes MoF6 and is etched. Further, when soda lime glass is used as the insulating substrate 1, Si becomes SiF4 and is etched. Further, the inclination angle θ of the first dividing groove 13 is controlled by adjusting the distance between the end of the parallel plate electrode that generates atmospheric pressure plasma and the insulating substrate 1, the distance between the parallel plate electrodes, the gas flow rate, and the like. be able to. In the microblasting process, the first divided grooves 13 can be formed by ejecting fine particles having a diameter of several μm from an ultrafine nozzle and scraping the first electrode film 2 and the insulating substrate 1. In order to adjust the inclination angle of the first divided groove 13 in microblasting, it can be controlled by the diameter of the nozzle that discharges the fine particles, the injection angle, and the like. Moreover, the 1st division | segmentation groove | channel 13 can be divided | segmented using a laser beam similarly to the conventional method, and the slope 13b can also be formed by scraping the insulating board | substrate 1 by a microblast process subsequently.

  According to the above configuration, the first split groove 13 having a trapezoidal cross section in which at least the left solar cell unit 11A side becomes the slope 13b is formed on the insulating substrate 1 on the left slope 13b of the first split groove 13. The thickness of the inclined laminated portion 7b of the formed second electrode film 7: d4 can be set to one half or more of the film thickness of the surface laminated portion 7a: d3, and the second electrode film of the inclined laminated portion 7b. 7 can be suppressed to less than twice the sheet resistance of the front laminated portion 7a. As a result, it is possible to prevent an increase in sheet resistance caused by the locally thin film thickness of the second electrode film 7 and a decrease in conversion efficiency due to this.

  Here, since the depth: x + d1 of the first dividing groove 13 is set to the film thickness of the semiconductor film 5: d2 ± the film thickness d3 of the second electrode film 7, the semiconductor film 5 is deleted up to the surface of the first electrode film 2. When the second dividing groove 16 is formed, a large step portion is not formed on the surface of the semiconductor film 5, and the film thickness of the second electrode film 7 is not locally reduced. Therefore, increase in sheet resistance can be prevented.

[Embodiment 2]
Embodiment 2 of an integrated thin film solar cell and a method for manufacturing the same according to the present invention will be described with reference to FIGS. The same members as those in the conventional example will be described with the same reference numerals.

FIG. 4 is a cross-sectional view of the series connection portion of the solar cell unit of the integrated thin film solar cell, and FIG. 5 is a partially enlarged view of the series connection portion.
As shown in FIG. 4, the first electrode film 2, the semiconductor film 5, and the second electrode film 7 are sequentially formed on the insulating substrate 1 to constitute solar cell units 11 </ b> A and 11 </ b> B. A slope forming groove 21 is formed on the insulating substrate 1 along the dividing direction of the solar cell unit. The first electrode film 2 is divided into strips by the first dividing grooves 23, the semiconductor film 5 is divided into strips by the second dividing grooves 26 having a rectangular cross section, and the second electrode film 7 is a third having a rectangular section. It is divided into strips by the dividing groove 28. Further, the first electrode film 2 of the left solar cell unit 11 </ b> A is exposed by the second divided groove 26 in the second divided groove 26 portion that divides the semiconductor film 5. Adjacent solar cell units 11A and 11B stacked on the film 2 are connected in series.

  The inclined surface forming groove 21 has a trapezoidal cross section, and includes a bottom surface 21a parallel to the surface of the insulating substrate 1 and left and right inclined surfaces 21b. The inclined surface 21b is inclined with respect to the surface of the insulating substrate 1 at a predetermined angle γ. Depth: y is formed, and the width is 50 μm to 5 mm.

  In addition, the first electrode film 2 laminated on the insulating substrate 1 and the slope forming groove 21 is formed on the surface laminated portion 2e formed on the surface of the insulating substrate 1 and the left and right slopes 21b of the slope forming groove 21. The inclined laminated portion 2 f is formed, and the bottom laminated portion 2 g formed on the bottom surface 21 a of the inclined surface forming groove 21. The film thickness d11 of the surface laminated portion 2e is formed to be 0.5 to 2 μm.

  And the 1st division groove 23 which divides | segments the 1st electrode film 2 is formed in the bottom laminated part 2g of the 1st electrode film 2 corresponding to the bottom face 21a of the slope formation groove | channel 21, and is formed in width | variety 10-200 micrometers. ing.

  Further, the semiconductor film 5 laminated on the first electrode film 2 and the first dividing groove 23 includes a surface laminated portion 5e formed on the surface laminated portion 2e of the first electrode film 2 and the left and right inclined laminated portions 2f. 5g, and the bottom laminated part 5g formed on the bottom laminated part 2g.

  The second divided groove 26 has a rectangular cross-sectional shape, and at least overlaps with the first electrode layer 2 of the solar cell unit 11B on the right side except for the upper side of the inclined surface forming groove 21, and here, a part of the inclined surface forming groove 21 also overlaps. The semiconductor layer 5 is deleted and a part of the first electrode film 2 of the right solar cell unit 11B is exposed.

  The second electrode film 7 laminated on the semiconductor film 5 and the second dividing groove 26 is formed on the surface laminated portion 7e formed on the surface laminated portion 5e of the semiconductor film 5 and the left inclined laminated portion 5f. The inclined laminated portion 7f, the bottom laminated portion 7g formed on the bottom laminated portion 5g, the connection portion T formed on the bottom surface of the second divided groove 26, and the side surface of the second divided groove 26. It is comprised by the side surface laminated part 7i. Note that a part of the side laminated portion 7 i and the connecting portion T is deleted by the third dividing groove 28.

  The third dividing groove 28 has a rectangular cross-sectional shape, and as shown in the drawing, the third dividing groove 28 partially overlaps the second dividing groove 26 and is removed from the side surface laminated portion 7i, so that the first electrode layer 2 of the solar cell unit 11B on the right side is removed. The surface has been deleted. However, the third dividing groove 28 may be formed at a position that does not overlap with the first dividing groove 26, but needs to be formed at a position that does not overlap with the slope forming groove 21 at all. This is because, when the third dividing groove 28 and the slope forming groove 21 overlap, the connection portion T of the second electrode film 7 that connects the adjacent solar cell units 11A and 11B is lost.

  In FIG. 5, y is the depth of the slope forming groove 21, and d <b> 11 is the film thickness of the surface laminated portion 2 e of the first electrode film 2, for example, 0.2 to 2 μm. Further, d12 is the film thickness of the surface laminated portion 5e of the semiconductor film 5, for example 1 to 5 μm, and d13 is the film thickness of the surface laminated portion 7e of the second electrode film 7, for example, 0.1 to 1 μm. Further, d14 indicates the thickness of the inclined laminated portion 7g of the second electrode film 7, and γ indicates the inclination angle of the left inclined surface 21b with respect to the surface of the insulating substrate 1 of the inclined surface forming groove 21, where 0 ° <γ ≦ The range is set to 60 °.

Here, the depth y of the slope forming groove 21 is substantially the same as the film thickness d12 of the semiconductor film 5. This is because when the difference between the depth of the slope forming groove 21: y and the film thickness of the semiconductor film 5: d12 is greatly different, the semiconductor film 5 is deleted up to the surface of the first electrode film 2 to form the second divided groove 26. This is because a vertical step portion is formed on the surface of the semiconductor film 5 and a thin film portion of the second electrode film 7 is formed on the vertical step portion, thereby increasing the sheet resistance. Therefore, the allowable range of the vertical step portion is the range of increase / decrease of the thickness of the second electrode film 7: d13 (± d13).
d12−d13 ≦ y ≦ d12 + d13 (2)

Next, the manufacturing method of the said integrated thin film solar cell is demonstrated with reference to Fig.6 (a)-(h).
As shown in FIG. 6A, an insulating substrate 1 made of, for example, soda lime glass is prepared. As shown in FIG. 6 (b), one inclined surface forming groove 21 is formed on the surface of the insulating substrate 1 for each solar cell unit 11A, 11B in a line shape perpendicular to the series direction of the integrated thin film solar cells. (Step B). The width of the insulating substrate 1 is, for example, 50 μm to 5 mm. As a means for forming the slope forming groove 21, microblasting is particularly effective. In the microblasting process, the slope forming groove 21 can be formed by ejecting fine particles having a diameter of several μm from an ultrafine nozzle and cutting the insulating substrate 1.

  As shown in FIG. 6C, the first electrode film 2 is formed on the insulating substrate 1 and the slope forming groove 21. As the first electrode film 2, for example, a Mo film is formed as a metal film by a sputtering method.

  As shown in FIG. 6D, the first divided grooves 23 are formed in a line shape in the first electrode film 2 in a direction perpendicular to the series direction of the integrated thin film solar cell. The width | variety of the 1st division groove 3 is 10-200 micrometers.

  As shown in FIG. 6E, the semiconductor film 5 is formed on the insulating substrate 1, the slope forming groove 21, and the first dividing groove 23. The semiconductor film 5 includes, for example, a light absorption layer, a buffer layer, and a window layer, a CIS compound semiconductor thin film is formed as a light absorption layer by a sputtering method or a multi-source deposition method, and a CdS film is deposited as a buffer layer by a CBD method, A ZnO film is formed as a window layer by sputtering.

  As shown in FIG. 6F, the second dividing groove 26 is formed in the semiconductor film 5 in a line shape parallel to the first dividing groove 23. The second dividing groove 26 is performed by a mechanical scribe method. The position of the second dividing groove 26 is 10 to 200 μm in width with the end on the right side of the slope forming groove 21 in the figure as the center.

As shown in FIG. 6G, the second electrode film 7 is formed. As the second electrode film 7, for example, an ITO film as a transparent conductive film is formed by a sputtering method.
As shown in FIG. 6H, the third dividing groove 28 is formed in a line shape in parallel with the second dividing groove 26 in the semiconductor film 5 and the second electrode film 7. The third dividing groove 28 may be a dividing groove of only the second electrode film 7. The third dividing groove 28 is formed by a mechanical scribing method.

  According to the above configuration, by forming the inclined surface forming groove 21 in the insulating substrate 1, the inclined stacked portion 5f of the semiconductor film 5 stacked on the inclined surface 21b has a gentle inclination angle γ, not vertical, and is 0 °. By forming it at <γ ≦ 60 °, the film thickness d4 of the inclined laminated portion 7f of the second electrode film 7 formed on the semiconductor film 5 is two times the film thickness 3d of the surface laminated portion 7e. One or more. Thereby, the sheet resistance of the inclined laminated portion 7f of the second electrode film 7 can be suppressed to less than twice the sheet resistance of the front laminated portion 7e.

  Here, the depth of the slope forming groove 21: y, the thickness of the semiconductor film 5: d12 ± the thickness d13 of the second electrode film 7, so that the semiconductor film 5 is deleted up to the surface of the first electrode film 2. When the second dividing groove 26 is formed, a large step portion is not formed in the semiconductor film 5, and the film thickness of the second electrode film 7 is not locally reduced. Therefore, increase in sheet resistance can be prevented.

  In the embodiment of the present invention described above, only a part of various variations are illustrated with respect to the type of the solar cell, the configuration of the laminated film, and the like in the application range of the present invention. In application of the present invention, it goes without saying that various variations other than those exemplified here can be considered.

In the first and second embodiments of the present invention, an ITO film that is a transparent conductive film is shown as the second electrode film 7, but a transparent conductive film containing at least one of ITO, ZnO, or SnO ₂ is shown. In this case, the present invention is also effective.

  Moreover, although the example of the CIS compound semiconductor thin film was shown as a light absorption layer about the semiconductor film 5, not only this but an I-III-VI group compound semiconductor is included, and especially I group element contains at least one among Cu or Ag. In particular, the present invention is particularly effective when the group III element contains at least one of Al, In or Ga and the group VI element contains at least one of Se or S.

  For example, as a type of solar cell, an example of a substrate-type CIS solar cell that generates power by being irradiated with light from the second electrode film 7 side is shown, but in addition, the first electrode 2 film is a transparent conductive film. In addition, a super straight type amorphous silicon solar cell in which the semiconductor film 5 is made of an amorphous silicon film, the second electrode film 7 is made of a metal film, and generates power by being irradiated with light from the insulating substrate 1 side is also within the scope of the present invention. is there.

BRIEF DESCRIPTION OF THE DRAWINGS It is Embodiment 1 of the integrated-type thin film solar cell concerning this invention, and is sectional drawing which shows the serial connection part of a solar cell unit. It is an expanded sectional view of the solar cell unit. (A)-(g) shows the procedure of the manufacturing method of the solar cell unit, respectively, and is sectional drawing of a serial connection part. It is sectional drawing which shows Embodiment 2 of the integrated thin film solar cell which concerns on this invention, and shows the serial connection part of a solar cell unit. It is an expanded sectional view which shows the serial connection part of the same solar cell unit. (A)-(h) shows the procedure of the manufacturing method of the solar cell unit, respectively, and is sectional drawing of a serial connection part. It shows a conventional integrated thin film solar cell and is a cross-sectional view of a serial connection portion of solar cell units. (A)-(g) shows the procedure of the manufacturing method of the solar cell unit, respectively, and is sectional drawing of a serial connection part. It is sectional drawing of the serial connection part of the solar cell unit which shows the modification of the conventional integrated thin film solar cell.

Explanation of symbols

T connecting portion θ, γ inclination angle 1 insulating substrate 2 first electrode film 2e surface laminated portion 5 semiconductor film 5a surface laminated portion 5b inclined laminated portion 5e surface laminated portion 5f inclined laminated portion 7 second electrode film 7a surface laminated portion 7b Inclined laminated portion 7e Surface laminated portion 7f Inclined laminated portion 11A Left side solar cell unit 11B Right side solar cell unit 13 First divided groove 13a Bottom surface 13b Slope 16 Second divided groove 18 Third divided groove 21 Slope forming groove 21a Bottom surface 21b Slope 23 First 1 divided groove 23a bottom surface 23b slope 26 second divided groove 28 third divided groove

Claims (13)

The first electrode film divided by the first dividing groove, the semiconductor film divided by the second dividing groove, and the second electrode film divided by the third dividing groove are sequentially insulated on the surface of the insulating substrate. A solar cell unit laminated with a substantially uniform film thickness in a direction perpendicular to the surface of the conductive substrate, the second electrode film of one solar cell unit and the first electrode film of the other solar cell unit being in contact with each other An integrated thin-film solar cell in which adjacent solar cell units are connected in series,
Forming the first dividing groove as a trapezoidal cross section over an insulating substrate;
A second electrode film surface laminated portion formed corresponding to the surface of the insulating substrate by an inclined laminated portion of the second electrode film formed on the inclined surface of the first dividing groove via a semiconductor film; An integrated thin-film solar cell configured to connect the second electrode film of the connecting portion on the first electrode film that is in contact with the three-divided groove. The thickness of the inclined forming part of the second electrode film is set to be ½ or more of the film thickness of the surface laminated part of the second electrode film formed on the surface of the insulating substrate via the semiconductor film. The integrated thin film solar cell according to claim 1. The integrated thin film solar cell according to claim 1, wherein an inclination angle θ on the groove side of the inclined surface of the first divided groove with respect to the surface of the insulating substrate is set to 0 ° <θ ≦ 60 °. The integrated thin-film solar cell according to any one of claims 1 to 3, wherein the depth of the first dividing groove is within the range of the thickness of the semiconductor film ± the thickness of the second electrode film. The second divided groove is formed around the edge of the first divided groove on the other solar cell unit side,
The third dividing groove is formed on the other solar cell unit side while leaving the connection portion of the second electrode film in contact with the first electrode plate of the other solar cell unit at the bottom of the second dividing groove. The integrated thin film solar cell according to claim 1. The first electrode film divided by the first dividing groove, the semiconductor film divided by the second dividing groove, and the second electrode film divided by the third dividing groove are sequentially insulated on the surface of the insulating substrate. A solar cell unit laminated with a substantially uniform film thickness in a direction perpendicular to the surface of the conductive substrate, and the first electrode film of one solar cell unit and the second electrode film of the other solar cell unit are in contact with each other An integrated thin-film solar cell in which adjacent solar cell units are connected in series,
A slope forming groove having a trapezoidal cross section with an inclined surface formed on at least one solar cell unit side is formed in the insulating substrate in parallel with the first to third divided grooves, and the first above the slope forming groove. Forming a first dividing groove in the electrode film;
The second divided groove is formed around the edge of the slope forming groove on the other solar cell unit side,
Forming the third dividing groove on the other solar cell unit side, leaving the second electrode film laminated on the first electrode surface on the other solar cell unit side edge of the inclined surface forming groove;
A second electrode film surface laminated portion formed corresponding to the surface of the insulating substrate by an inclined laminated portion of the second electrode film formed on the inclined surface of the inclined surface forming groove via a semiconductor film; An integrated thin-film solar cell characterized in that it is configured to connect a connection portion of the second electrode film on the first electrode film that is in contact with the dividing groove. The integrated thin film solar cell according to claim 6, wherein the thickness of the inclined laminated portion of the second electrode film is ½ or more of the thickness of the surface laminated portion of the second electrode film. The integrated thin-film solar cell according to claim 6 or 7, wherein an inclination angle γ of the inclined surface of the inclined surface forming groove with respect to the surface of the insulating substrate is set to 0 ° <γ ≦ 60 °. The integrated thin-film solar cell according to any one of claims 6 to 8, wherein the depth of the slope forming groove is within the range of the film thickness of the semiconductor film ± the film thickness of the second electrode film. Corresponding to the method of Embodiment 1 On the surface of the insulating substrate, the first electrode film divided by the first dividing groove, the semiconductor film divided by the second dividing groove, and the first electrode divided by the third dividing groove The two-electrode film includes a solar cell unit laminated on the surface of the insulating substrate in order, and the first electrode film of one solar cell unit and the second electrode film of the other solar cell unit are in contact with each other and adjacent to each other. When manufacturing an integrated thin film solar cell in which solar cell units are connected in series,
Forming a first dividing groove on the insulating substrate on which the first electrode film is laminated;
On the first electrode film and the first dividing groove, after forming a semiconductor film having a uniform thickness in a direction perpendicular to the surface of the insulating substrate, a second dividing groove is formed in the semiconductor film,
Forming a second electrode film having a uniform thickness on the semiconductor film and the second dividing groove in a direction perpendicular to the surface of the insulating substrate;
In a position that does not overlap the first dividing groove, the second electrode film and the semiconductor film 5 are deleted up to the surface of the first electrode film to form a third dividing groove,
A method of manufacturing an integrated thin-film solar cell, characterized in that an inclination angle γ on the removal side of the inclined surface of the second divided groove with respect to the surface of the insulating substrate is 0 ° <γ ≦ 60 °. The method for producing an integrated thin-film solar cell according to claim 10, wherein the step of forming the first divided groove is performed by one of microblasting and fine processing by atmospheric pressure plasma. A first electrode film divided by the first dividing groove, a semiconductor film divided by the second dividing groove, and a second electrode film divided by the third dividing groove are sequentially stacked on the surface of the insulating substrate. Integrated thin-film solar cell in which the first electrode film of one solar cell unit and the second electrode film of the other solar cell unit are in contact with each other and adjacent solar cell units are connected in series In manufacturing
A slope forming groove having a trapezoidal cross section is formed on the surface of the insulating substrate 1,
Forming a first electrode film having a uniform thickness in a direction perpendicular to the surface of the insulating substrate on the insulating substrate and the inclined surface forming groove;
Forming a first dividing groove in the first electrode film formed on the inclined surface forming groove;
Forming a semiconductor film having a uniform thickness on the first electrode film and the first dividing groove in a direction perpendicular to the surface of the insulating substrate;
Forming a second divided groove corresponding to the edge of the slope forming groove on the other solar cell unit side;
On the semiconductor film and the second dividing groove, a second electrode film 7 having a uniform film thickness is formed in a direction perpendicular to the surface of the insulating substrate,
The third divided groove 8 is formed in the second electrode film by being displaced from the inclined surface forming groove to the other solar cell unit side,
A method of manufacturing an integrated thin-film solar cell, characterized in that an inclination angle γ on the removal side of the inclined surface of the second divided groove with respect to the surface of the insulating substrate is 0 ° <γ ≦ 60 °. 13. The method of manufacturing an integrated thin film solar cell according to claim 12, wherein the slope forming groove is formed by microblasting.

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