JPS60149178A - Solar cell - Google Patents

Abstract

PURPOSE:To enable most part of the whole area of a substrate to be ensured as the photoelectric generating region by a method wherein photoelectromotive force generating in a photoelectric conversion semiconductor layer is led out of a collectrode via conductor penetrating from the front side to the back side. CONSTITUTION:A photo transmitting surface electrode 11, the photoelectric conversion semiconductor layer 2, first collector electrode 12, an insulation layer 13, and the second collector electrode 14 are successively laminated on a glass substrate 5; then, the electrode 11 is connected to the electrode 14 by means of the connection conductor passing through a hole 15 penetrating through the layer 13, electrode 14, and layer 2. This conductor 16 has a diameter smaller than the hole, and its gap is filled with the layer 13. In this solar cell, photocurrents generating in the layer 2 flow through the electrode 11 in the plane direction of the substrate and then collected to the electrode 14 after flowing perpendicularly to the substrate 5. Thereafter, the photocurrents can be led out via electrode 12 and electrode 14. This construction enables most part of the whole area of the substrate to be ensured as the photoelectric generating region because connection parts of the electrodes 12 and 14 and the elements are all formed on the anti-photo receiving plane side.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a solar cell that generates photovoltaic power using a semiconductor, particularly a semiconductor thin film such as an amorphous silicon layer.

[Prior art and its problems]

In order to improve the energy conversion efficiency of solar cells, which perform multiple tangent conversion of light energy into electrical energy, the factors that govern the energy conversion efficiency are determined in the process from irradiating the solar cell with light energy to extracting electrical energy. It is classified and analyzed in detail, including the element materials, physical properties,
Many studies have been conducted regarding the manufacturing conditions for controlling this. However, in order to ultimately obtain high energy conversion efficiency as a solar cell, in addition to basic studies on aggregate physical properties, it is necessary to design anti-reflection coatings to maximize the use of incident light energy. And designing a current collecting electrode to make maximum use of the generated photocurrent is a one-time expense.

Furthermore, in order to apply solar cells as electrolytic corrosion equipment for industrial or consumer equipment, it is necessary to generate output voltages that are matched to each equipment.

FIG. 1 shows an example of a conventional solar cell. FIG. 1 (al is a plan view seen from the light-receiving surface side, FIG. 1 (bl is a cross-sectional view taken along the line 8-1), and FIG. 1 1cI is a B-H+1tiivfr plane view.

This solar cell has a photoelectric conversion semiconductor layer 2 formed on a metal substrate 1 which serves as a back electrode, and has a grid-like collector electrode 3 made of a trunk 31 and a plate portion 32 thereon. This current collecting electrode 3 is formed by vacuum evaporation of a conductive metal, for example, and collects the photocurrent generated by the incidence of light 4 on the semiconductor layer 2 at the branch portion 32 and transports it to the outside through the main body 31. . The branch portion is formed thin so as not to cover the light-receiving surface side of the semiconductor layer 2 as much as possible, and has a width of 0.2 SO, 4 rm, and has a width of 0.2 SO, 4 rm.
has a width of 3 to 10 wA to minimize energy loss due to direct current resistance during transport of the photocurrent collected at the branch 32 to the output terminal. The design of this lattice-shaped collector electrode 3 takes into account factors such as the output characteristics of the photoelectric conversion semiconductor layer, the sheet resistance of the semiconductor surface layer, the sheet resistance of the collector electrode material, the photocurrent transport distance, the electrode formation method, and MIjl. do. However, even if the grid electrode is optimally designed to ultimately obtain the maximum output as a solar cell, the grid electrode 3 (trunk 31 and branch 3
The area occupied by 2) ranges from 10 to 30 inches. The lattice electrode does not have a photovoltaic function, and the lattice electrode blocks the energy of light incident on the photoelectric conversion semiconductor layer formed below the lattice electrode, making it impossible to generate photovoltaic power. In a solar cell that has a grid-like electrode on the light-receiving surface side, there are always 10 to 30 areas that do not have a photovoltaic function in the total area of the solar cell substrate.
Chi exists.

Therefore, the area having a photovoltaic function is limited to 70 to 90 inches. Furthermore, when the photoconversion element is increased in m, the photocurrent to be collected increases and its transport distance becomes longer. This results in a reduction in the area having a photovoltaic function. Furthermore, the output voltage of the solar cell element shown in Figure 1 alone is low; for example, a single crystal silicon solar cell has a low output voltage of 0.6V, and an amorphous silicon solar cell has a voltage of about 0.
．． Since it is 8V, it cannot be used as a power source for equipment that requires high voltage. For this reason, in order to obtain a high voltage, many elements were wired in series using interconnectors such as copper foil. However, the cost of this wiring makes the entire solar cell device expensive.

Fig. 2 shows another conventional example using a glass substrate. A photoelectric conversion semiconductor layer 2 is provided on a glass substrate 5 via a transparent electrode 6,
A metal back electrode 7 is deposited thereon. A finger-shaped electrode 8 is provided in a portion of the transparent electrode 6 that is not covered by the semiconductor layer 2 and the metal electrode 7. In this solar cell, the photocurrent generated in the semiconductor layer 2 due to the incidence of light 4 from the glass substrate 5 side is collected through the transparent electrode 6 to the finger-shaped electrode 8, and further to the output terminal by the finger-shaped electrode 8 itself. It is meant to be transported. For example, the transparent electrode 6 has a visible light transmittance of 70 to 90 and a sheet resistance of 10 to 100 Ω/mouth (specific resistance is 10-3
A transparent conductive film of ˜10→Ωtm) is applied. The photocurrent flows through this transparent electrode 6 in the plane direction of the glass substrate 5. Therefore, in this solar cell design, the photocurrent transport distance in the transparent electrode 6, ie, the width of the transparent electrode 6, is limited by its sheet resistance. The width of the transparent electrode 6 is 5 to 10 m in order to minimize energy loss in the transparent electrode 1.

In this way, in the solar cell shown in FIG.
It has a structure in which photoelectric conversion regions having a + width are connected in parallel. Furthermore, the finger electrodes 8 have a width of 1 to 3 strips and have an insulating part 9 of about 1 mm between the finger electrodes 8 and the metal electrodes 7. The finger electrodes 8 and the insulating portions 9 do not have a photovoltaic function.

As described above, there are regions in which no photovoltaic power is generated between the photoelectric conversion regions having a width of 5 to 10 wn, and in one of the details, and the area thereof is 30 to 50% of the total area of the glass substrate 5. Therefore, the photovoltaic area is limited to 50-70%. Furthermore, when the area of the photoelectric conversion semiconductor layer 2 is increased, the photocurrent to be collected increases and its transport distance becomes longer, resulting in energy loss due to series resistance loss in the finger electrodes 8, which reduces the energy conversion efficiency of the solar cell. descend.

Alternatively, increasing the width of the finger electrodes to reduce series resistance losses further reduces the leading L&

FIG. 3 shows another conventional example, and is a cross-sectional view taken along line 3 (al is a plan view seen from the gray light-receiving surface, and FIG. 2 1bJ is part 1). This solar cell has a solar cell element 1 having a layered structure formed on a glass substrate 5 similar to the conventional example shown in FIG.
0, and each solar cell element lO
Connect in series.

The width of each element is limited to 5 to 10 strips for the same reason as in FIG. However, in the solar cell shown in FIG. 3, the line-shaped series connection portion 61. Line-shaped insulating portions between adjacent elements 10, that is, transparent electrodes 6 and metal electrodes 7 of adjacent elements
The distance between the output terminal 8 and the output terminal 8 does not have a photovoltaic function.

As described above, there are linear non-photovoltaic generating areas at intervals of 5 to 10+ m, and the area thereof is as much as 20 to 40% of the total area of the glass substrate. Therefore, the area having a photovoltaic function is limited to 60 to 80 inches.

FIG. 4 shows another conventional example. FIG. 3 (al is a plan view seen from the gray light-receiving surface side, FIG. 3 (bl is a sectional view taken along the line E-E, and FIG. 3 1cI is a sectional view taken along the line F'-F).

In this case as well, a glass substrate 5 is provided, but a transparent electrode 6° and a photoelectric conversion semiconductor layer 2. Solar cell element 10 consisting of metal electrode 7
The series connection of the transparent electrode extension part 62 and the metal electrode extension part 71
It will be held in However, in this case as well, the area of the transparent electrode 6 is limited due to its sheet resistance, and in addition to the insulating part between the elements, the part where the extension part of both electrodes 6 and 7 for connection exists cannot be used for photovoltaic power generation. As the number of series connections increases, the series resistance loss in the transparent electrode extension 62 increases, and the energy conversion efficiency of the solar cell is significantly restricted.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of conventional solar cell structures, provide a solar cell that has a large area usable for photovoltaic power generation, and has low series resistance loss.

[Key points of the invention]

The solar cell according to the present invention includes a transparent substrate, a light-transmitting surface electrode, a photoelectric conversion semiconductor ring, a first current collecting electrode, and an insulating layer 1.
m2 current collecting electrodes are stacked, the second current collecting electrode and the surface electrode pass through the insulating layer, the first collecting electrode and the through hole of the semiconductor layer,
The above object is achieved by being connected to the second current collecting electrode by an insulated conductor. A plurality of solar cell elements having such a structure are provided on a common transparent substrate, and by connecting each element in series by bringing the second current collecting electrode into contact with the first current collecting electrode of an adjacent element, an arbitrary output voltage can be obtained. It is possible to obtain a solar cell having

[Embodiments of the invention]

The present invention will be explained below with reference to the drawings. In each figure, the same reference numerals are used for parts common to the previous figures. FIG. 5 shows the basic structure of the solar cell according to the present invention,
A transparent surface electrode 11 is placed on the glass substrate 5. Photoelectric conversion semiconductor layer 2. First current collecting electrode 12, insulating layer 13. The second collector electrode 14 is laminated in sequence, and the surface electrode 11 and the second collector 'thl!
The electrode 14 is the insulating layer 13. It is connected by a connecting conductor 16 made of the same material as the second current collecting electrode 14 passing through a hole 15 penetrating the second current collecting electrode 14 and the semiconductor layer.

This conductor 16 has a smaller diameter than the through hole 15, and the gap therebetween is filled with the insulating layer 13.

As for the material constituting such a solar cell, it is desirable to use a material with a sheet resistance of 10"07 or less for the transparent surface layer 11, such as indium oxide doped with soot oxide or tin oxide doped with antimony oxide. A transparent conductive oxide film such as, a metal thin film such as aluminum or platinum, or a low resistance surface layer of the photoelectric conversion semiconductor layer 2 can be applied.Photoelectric conversion semiconductor layer 2
Thin films such as amorphous silicon, compound semiconductors, and organic medium conductors can be applied. Current collecting electrode 12.
It is desirable that the material No. 14 has a specific resistance of IO-2 Ωm or less, and metals (such as aluminum, copper, gold, etc.) are preferable.
It is possible to use conductive materials such as nickel (nickel, etc.), graphite, semiconductors, etc., or 4-abrasive paints in which these conductive materials are dispersed in polymers or glass frit. The insulating layer 13 can be made of a polymeric material such as epoxy resin or an inorganic material such as silicon oxide. The function of the insulating layer 13 is to connect the first current collector to the electrode 12 and the second current collector.
This is something that intervenes between the cables 14 and insulates the two.

The method for forming the valley constituent material is -X nitrogen evaporation method.

Sputtering method, vapor phase growth method, glow discharge method.

Film forming techniques such as screen printing and spray coating can be applied.

FIG. 6 shows an example of the manufacturing process of a solar cell having such a structure. On the glass substrate 5, about 20
A transparent conductive oxide film 11 with a thickness of 0 OA is formed by sputtering (FIG. 6(a)), and then an amorphous silicon film 2 with a thickness of about 1 μm is formed as a photoelectric conversion semiconductor layer by a glow discharge method. (bl) As a first current collecting electrode, an aluminum film 12 having a thickness of about 0.5 μm is formed by a vacuum evaporation method (FIG. 6(C)). Subsequently, as shown by the ridges in FIG. 6, the aluminum film 12 and the semi-enveloped layer 2 are patterned by photolithography to form through holes 15.

Next, as shown in FIG. 6, an insulating layer with a thickness of about 10
An epoxy resin layer 13 of μm thickness is formed by screen printing, and as shown in FIG.
1 and the second current collecting electrode 14 electrically connected to the negative through hole 1
A conductor 16 filling the conductor 5 is formed to a thickness of about 20 μm using a silver paste screen printing method.

In such a solar cell, when the amorphous silicon film 2 is laminated in the order of p layer + 1Itll vn layer from the surface electrode 11 side, the first current collecting electrode 12 becomes a negative electrode and the second current collecting electrode 14 becomes a positive electrode.

FIG. 7 shows an embodiment of the present invention, and FIG. 7 (al is a plan view seen from the light receiving surface side, FIG. FIG. 7 fdl is a sectional view taken along line GG in FIG. ibl, and line HH in FIG. It is in contact with the surface electrode 11,
On the insulating layer 13, a parallel band shape is formed, and a connecting portion 17 is formed.
and is connected to the second output terminal 19. On the other hand, a part of the first current collecting pole 12 is exposed from the insulating layer 13 and forms a first output terminal 18 . In this solar cell, the semiconductor layer 2
The photocurrent generated flows through the surface electrode 11 in the plane direction of the glass substrate 5, flows through the linearly formed connecting conductor 16 perpendicularly to the substrate 5, and is collected by the second electric current collector 12. . The collected photocurrent is transported to the second output terminal 19 through the second collecting m-electrode 14°17. Therefore, the photocurrent can be taken out from a portion of the first output terminal 18 and the second output terminal 19 of the first current collecting electrode 12.

The connecting conductors 16 must be provided at appropriate intervals so as to minimize energy loss due to series resistance in the surface electrode 11. A photoelectric conversion semiconductor layer 2 was formed on a 10 cm x 10 cm glass substrate 5 (area 1 (10 cIl)), the width of the linear connection conductor 16 was 0.2 mm, and the insulation 1 -
13, that is, the distance between the connecting conductor 16 and the semiconductor layer 12 is 0.2 Wn, and when five linear connecting conductors 16 are provided at an interval of about 2 an, the photovoltaic power generation for the area of the glass substrate 5 is The non-functional area, that is, the portion occupied by the connecting conductor 16 and the insulating layer 13, is about 3%, and therefore the area with the photovoltaic function is about 97%, which is compared to the conventional example 5 shown in FIG. ( ) to 7 (significantly improved compared to Nochi).

8 shows another embodiment, FIG. 8 131 is a plan view seen from the light receiving surface side, FIG. 8 131 is a plan view seen from the gray light receiving surface side, FIG. 131 in FIG. 8, respectively. In this case, the insulating layer 13, the second current collecting electrode 14
The hole 15 penetrating the semiconductor layer 2 is circular, the connecting conductor 16 has a diameter that is partially smaller than the through hole 15, and the gap is filled with the insulating layer 13.

Surface electrode 11. Semi-woven body layer 2. The first current collecting electrode 12 has the same area, and the insulating layer 13 covers the entire surface, but the second current collecting electrode 14
As can be seen from Fig. 8 (tbl force), it is formed locally. A plurality of solar cell elements 10 having such a configuration are formed on a common glass substrate 5, and the first current collecting electrode 12 and the second current collecting electrode 14 of adjacent elements are connected to a second collecting electrode with a separation insulating layer 20 interposed therebetween. They are connected in series by connecting through the extensions 24 of the tg poles.

In such a solar cell, a photocurrent generated by light 4 incident from the side of the glass substrate 5 flows through the surface electrode 11 flatly with respect to the glass plate surface, and then flows from the connecting conductor 16 to the glass plate surface. flow in the vertical direction, and the second current collecting electrode 1
4, the first current collector electrode 12 and the second current collector 5 current 4iJ
! A voltage is generated between 14 and 14. The connecting conductors 16 must be provided at appropriate intervals so as to minimize energy loss due to linear resistance in the surface electrode 11. By electrically connecting each solar cell element in series through the extension part 24 of the second current collecting electrode 14, photocurrent is transported to the first output terminal 18 and the second output terminal 19, and each element is connected between both terminals. A voltage is generated that is the sum of the voltages generated in .

In this solar cell, the area that does not have a photovoltaic function is only the sum of the cross-sectional areas of the through holes 15, so the area that has a photovoltaic function reaches 95 inches or more of the area of the glass substrate 5.

〔Effect of the invention〕

In the solar cell according to the present invention, the photovoltaic force generated in the photoelectric conversion semiconductor layer provided on the transparent substrate via the light-transmitting front electrode is transferred to the surface via the back electrode and the conductor penetrating from the front side to the back side. The second current collector electrode is connected to the second collector electrode, and has the following advantages.

(1) Since the connection parts between the two current collectors' single poles, output terminals, or elements are formed on the light emitting/receiving surface side, even if they are made of opaque material, the area with the photovoltaic function will not be reduced. It is possible to secure most of the total area as a photovoltaic power generation area.

(2) When solar cells are made to have a large area, such as 1 m x 1 m, the photocurrent to be collected increases1, and even if the transport distance becomes longer, the current collecting electrode is located on the light emitting/receiving surface side. Therefore, by increasing the width of the current collecting electrode, energy loss due to series resistance can be reduced.

(3) Each element can be created and connections between elements can be made by forming each layer and patterning it using vacuum evaporation, vapor phase growth, etc., making it easy to mass-produce solar cells with arbitrary output. It is possible to produce low-cost solar cells.

As described above, the structure of the solar cell according to the present invention maximizes the function of the photoelectric conversion element within a restricted area.

[Brief explanation of the drawing]

Figure 1 shows an example of a conventional solar cell.
1bl is a sectional view taken along the line A-A of FIG. 1(al), FIG. is a top view, and Figure 1 1bl is a top view.
Figure (C-C @ main part sectional view of al, Figure 3 is another conventional example (
1c) is a sectional view taken along the line FF, FIG. 5 is a sectional view showing the basic structure of the embodiment of the present invention, and FIGS. 6 181 to 181! 181 is a bottom view, FIG. 1 1bl is a top view, and FIG.
181 is a sectional view of the GG kneading part in FIG. 7 1bl, FIG. Figure 8 (bl is a top view,
Fig. 8 tc+ is a sectional view of the I-I kneading section in Fig. 1 1bl, y
, 6, 1dl is a sectional view taken along the line J-J, and FIG. 8 tel is a sectional view taken along the line 2-2. 2... Photoelectric conversion semiconductor layer, 5... Glass substrate, 10...
...Solar cell element, 11...Transparent surface electrode, 12...
- First current collecting electrode, 13 - Insulating layer, 14 Second current collecting electrode,
15 - Through hole, 16... Connection conductor. Sai 3 Illustration Sai 4 Illustration T 5 Illustration R Otsu Csu Sai 7 Illustration Sai 7 Illustration

Claims (1)

[Claims] 1) A light-transmitting surface electrode, a photoelectric conversion semiconductor layer, a first current collection electrode, an insulating layer, and a second current collection electrode are laminated on a transparent substrate, and the second current collection electrode and the surface A solar cell characterized in that an electrode passes through a through hole in an insulating layer, a first current collecting electrode, and a semiconductor layer, and is connected to the first current collecting electrode by an insulated conductor. 2. The battery according to claim 1, which is composed of a plurality of elements provided on a common transparent substrate, and each element is connected in series by the second current collecting electrode being in contact with the first current collecting electrode of an adjacent element. A solar cell characterized in that it is connected.