JP2016103583A - Photoelectric conversion module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable photoelectric conversion module capable of obtaining high electric power over a long period of time by reducing an increase in resistance of a wiring conductor.SOLUTION: A photoelectric conversion module 101 includes: a substrate 1 having one main surface; a photoelectric conversion part 11 arranged on the one main surface; a belt-like output electrode 8 arranged on the one main surface or the photoelectric conversion part 11 so as to be electrically connected to the photoelectric conversion part 11 and extending in one direction; a belt-like wiring conductor electrically connected to the output electrode 8 and led out to a rear surface of the substrate 1 through a through-hole 1a provided in the substrate 1 or through a side surface of the substrate 1; and a sealing material covering the photoelectric conversion part 11 and the wiring conductor. The wiring conductor has a first wiring conductor 9 connected to the output electrode 8 and a second wiring conductor 19 led out to the rear surface from the one main surface of the substrate 1. A surface part of the second wiring conductor 19 has higher resistance to corrosion due to moisture than a surface part of the first wiring conductor 9.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a photoelectric conversion module including a wiring conductor for taking out electric power generated by a photoelectric conversion unit.

  In recent years, photovoltaic power generation that converts light energy into electric energy has attracted attention as energy problems and environmental problems become more serious.

In the photoelectric conversion module used for this photovoltaic power generation, the electric power obtained from the photoelectric conversion unit is taken out through a wiring conductor such as a lead wire. In such a photoelectric conversion module, a photoelectric conversion part is formed using a semiconductor layer in the center part of the surface of the substrate, and wiring conductors respectively connected to the positive electrode and the negative electrode of the photoelectric conversion part are on the surface of the substrate. After being routed around the photoelectric conversion portion, it is led out into a terminal box disposed on the back surface of the substrate.
(For example, refer to Patent Document 1).

JP 2010-056251 A

  In the photoelectric conversion device as shown in Patent Document 1, the wiring conductor drawn out on the back surface of the substrate tends to be corroded by external moisture. As a result, when used for a long period of time, the electrical resistance of the wiring conductor is increased, making it difficult to efficiently extract power.

  Therefore, the present invention provides a highly reliable photoelectric conversion module capable of reducing the increase in resistance of a wiring conductor and obtaining high power over a long period of time.

  A photoelectric conversion module according to an aspect of the present invention includes a substrate having one main surface, a photoelectric conversion unit disposed on the one main surface, and the photoelectric conversion unit on the one main surface or on the photoelectric conversion unit. A band-shaped output electrode extending in one direction and disposed so as to be electrically connected to the output electrode, and electrically connected to the output electrode, through a through-hole provided in the substrate, or on a side surface of the substrate And a strip-shaped wiring conductor led to the back surface of the substrate, and a sealing material covering the photoelectric conversion portion and the wiring conductor, and the wiring conductor is connected to the output electrode. The first wiring conductor and the second wiring conductor led out from the one main surface to the back surface, and the surface portion of the second wiring conductor compared to the surface portion of the first wiring conductor Is characterized by high resistance to corrosion by moisture.

  According to the photoelectric conversion module of one embodiment of the present invention, it is possible to reduce the increase in resistance of the wiring conductor and obtain high power over a long period of time.

It is a perspective view in the state where the sealing material of the photoelectric conversion module concerning a 1st embodiment is not provided. It is a top view of the photoelectric conversion module of FIG. It is a principal part enlarged view which shows the connection part of the 1st wiring conductor in FIG. 2, and a 2nd wiring conductor. It is sectional drawing of the connection part of the 1st wiring conductor and the 2nd wiring conductor in the AA line of FIG. It is sectional drawing of the connection part of the 1st wiring conductor and the 2nd wiring conductor in the BB line of FIG. It is sectional drawing which shows the principal part of the photoelectric conversion part in the photoelectric conversion module of FIG. It is a perspective view which shows the principal part of the photoelectric conversion part in the photoelectric conversion module of FIG. It is a perspective view of the state which has not provided the sealing material of the photoelectric conversion module which concerns on 2nd Embodiment. It is a top view of the photoelectric conversion module of FIG.

  A photoelectric conversion module according to one embodiment of the present invention will be described with reference to the drawings. In each figure, right-handed XYZ coordinates with the X-axis as the arrangement direction of photoelectric conversion cells described later are attached.

<Photoelectric Conversion Module According to First Embodiment>
1 to 7 show the configuration of the photoelectric conversion module 101 according to the first embodiment in a state in which the sealing material is removed in order to make the configuration of wiring conductors and the like easier to see.

  The photoelectric conversion module 101 includes a substrate 1, a photoelectric conversion unit 11, an output electrode 8, a first wiring conductor 9, and a second wiring conductor 19.

  The substrate 1 has a function of supporting the photoelectric conversion unit 11. Examples of the material of the substrate 1 include blue plate glass (soda lime glass) or borosilicate glass having a thickness of about 1 to 3 mm. Note that the material of the substrate 1 is not limited to this, and other glass, ceramics, resin, metal, or the like may be used. Moreover, the shape of the board | substrate 1 should just be flat form, such as rectangular shape and circular shape, for example.

  The photoelectric conversion unit 11 is provided on one main surface of the substrate 1. In the photoelectric conversion unit 11, a plurality of photoelectric conversion cells are electrically connected to each other and integrated on the substrate 1 from the viewpoint of increasing the output of power generation. The overall shape of the photoelectric conversion unit 11 when the photoelectric conversion module 101 is viewed in plan is a rectangular shape. Details of the photoelectric conversion unit 11 will be described later.

  The output electrode 8 is provided on one main surface of the substrate 1 so that a pair of electrodes are electrically connected to the pair of electrodes of the photoelectric conversion unit 11. In the example of FIGS. 1 to 7, the output electrode 8 is a pair of an output electrode 8 </ b> A connected to one electrode of the photoelectric conversion unit 11 and an output electrode 8 </ b> B connected to the other electrode of the photoelectric conversion unit 11. The example which has is shown. Note that the output electrode 8 may be provided on the upper surface of the photoelectric conversion unit 11 instead of being located on the main surface of the substrate 1 outside the photoelectric conversion unit 11.

  The output electrode 8 may be a thin film containing a metal such as molybdenum (Mo), aluminum (Al), titanium (Ti), tantalum (Ta), gold (Au), or an alloy thereof. Moreover, the structure formed by laminating | stacking these metals may be sufficient. The output electrode 8 may be formed to a thickness of about 0.2 to 1 μm on the substrate 1 by using a sputtering method or a vapor deposition method, for example. From the viewpoint of simplifying the process, the output electrode 8 may be manufactured at the same time as the lower electrode layer 2 with the same material as the lower electrode layer 2 described later.

  The first wiring conductor 9 and the second wiring conductor 19 function as a conductive path for taking out the electric power generated by the photoelectric conversion unit 11 to the outside of the photoelectric conversion module 101.

  The first wiring conductor 9 is disposed along the first side of the photoelectric conversion unit 11 so as to extend in a strip shape in a first direction (Y-axis direction) parallel to the first side. Further, the first wiring conductor 9 is connected to the output electrode 8, whereby the photoelectric conversion unit 11 and the first wiring conductor 9 are electrically connected. The first side of the photoelectric conversion unit 11 is the + X side and −X side sides (sides parallel to the Y axis) of the photoelectric conversion unit 11 indicated by the thick rectangular lines in FIG. . In the example of FIGS. 1 to 7, the first wiring conductor 9 is a pair of the first wiring conductor 9A connected to the output electrode 8A and the first wiring conductor 9B connected to the output electrode 8B. The example which has is shown.

  One end of the second wiring conductor 19 is connected to the first wiring conductor 9 and passes through a through hole 1a provided in the substrate 1 as shown in FIGS. The other end is led out to the back surface of the substrate 1. The surface portion of the second wiring conductor 19 has higher corrosion resistance due to moisture than the surface portion of the first wiring conductor 9.

  With such a configuration, even if moisture enters the vicinity of the through-hole 1a from the back side of the substrate 1, the conductive path including the first wiring conductor 9 and the second wiring conductor 19 has a high resistance (electric resistance). Can be reduced). As a result, the photoelectric conversion module 101 capable of obtaining high power over a long period can be obtained.

  The reason why the surface portion of the second wiring conductor 19 is higher in corrosion resistance due to moisture than the surface portion of the first wiring conductor 9 is that the surface portion of the second wiring conductor 19 and the first wiring conductor 9 When the surface portion is brought into contact with water, the surface portion of the second wiring conductor 19 is less likely to have high resistance due to corrosion.

The first wiring conductor 9 is made of a conductor such as silver (Ag) or copper (Cu) from the viewpoint of improving electrical connection with the output electrode 8. The first wiring conductor 9 has a strip shape with a thickness of about 0.3 to 2 mm and a width of about 2 to 6 mm. The first wiring conductor 9 is electrically connected to the output electrode 8 by soldering, bonding with a conductive adhesive, or welding such as ultrasonic welding.
From the viewpoint of reducing the height of the surface of the first wiring conductor 9 from the surface of the output electrode 8, the first wiring conductor 9 may be connected to the output electrode 8 by welding.

  The second wiring conductor 19 only needs to have a higher corrosion resistance than at least the surface portion of the first wiring conductor 9. That is, the second wiring conductor 19 may be entirely made of a material having higher corrosion resistance than the surface portion of the first wiring conductor 9, and the first wiring conductor 19 may be formed on the surface of the highly conductive main body portion such as Ag or Cu. A film having a higher corrosion resistance than the surface portion of the wiring conductor 9 may be applied. When all the second wiring conductors 19 are made of a material having higher corrosion resistance than the surface portion of the first wiring conductor 9, the second wiring conductor 19 has higher corrosion resistance and can further reduce the increase in resistance of the wiring conductor. Further, when the second wiring conductor 19 is a film having a higher corrosion resistance than the surface portion of the first wiring conductor 9 on the surface of the main body portion having high conductivity such as Ag and Cu, Both electrical conductivity and corrosivity can be increased.

  When the surface portion of the first wiring conductor 9 is Ag or Cu, at least the surface portion of the second wiring conductor 19 is made of a material capable of forming a passive state such as aluminum (Al), or Ag or Cu such as platinum. Any material that has a lower ionization tendency may be used. The second wiring conductor 19 has a strip shape with a thickness of about 0.1 to 2 mm and a width of about 2 to 6 mm.

As shown in FIGS. 1 to 5, the first wiring conductor 9 and the second wiring conductor 19 may be connected on the output electrode 8. In particular, as shown in FIGS. 3 to 5, in the connection portion between the first wiring conductor 9 and the second wiring conductor 19, a part of the second wiring conductor 19 is positioned on the first wiring conductor 9. In addition, the other part of the second wiring conductor 19 may be connected to the output electrode 8 by soldering, bonding with a conductive adhesive, welding, or the like. In such a configuration, since the second wiring conductor 19 is fixed to the output electrode 8, the connection reliability between the first wiring conductor 9 and the second wiring conductor 19 becomes higher. Further, from the viewpoint of reducing the height of the surface of the second wiring conductor 19 from the surface of the first wiring conductor 9, the first wiring conductor 9 and the second wiring conductor 19 may be connected by welding. Good.

  The photoelectric conversion unit 11, the output electrode 8, the first wiring conductor 9, and the second wiring conductor 19 provided on the substrate 1 are sealed with a sealing material (not shown). Examples of the sealing material include a resin mainly composed of copolymerized ethylene vinyl acetate (EVA) and a resin mainly composed of polyvinyl butyral (PVB).

<Photoelectric conversion unit>
Next, the photoelectric conversion unit 11 will be described. FIG. 6 is a partial cross-sectional view showing the photoelectric conversion unit 11 at the center in the Y direction of the photoelectric conversion module 101, and FIG. 7 is a perspective view of the main part of the part. 6 and 7 show an example of the photoelectric conversion unit 11 used in the photoelectric conversion module 101, and the present invention is not limited to this.

  The photoelectric conversion unit 11 includes a lower electrode layer 2, a first semiconductor layer 3, a second semiconductor layer 4 having a conductivity type different from the first semiconductor layer 3, an upper electrode layer 5, and a collecting electrode 6. A plurality of photoelectric conversion cells 10 having the above are connected in series in the X direction of FIG. In the adjacent photoelectric conversion cell 10, the upper electrode layer 5 of one photoelectric conversion cell 10 is connected to the lower electrode layer 2 of the other adjacent photoelectric conversion cell 10 through the collector electrode 6 and the connection conductor 7. An output electrode 8A is formed outside one end of the photoelectric conversion unit 11, and is electrically connected to the lower electrode layer 2 of the photoelectric conversion cell 10 on the one end side. An output electrode 8B is also formed outside the other end of the photoelectric conversion unit 11 on the opposite side, and is electrically connected to the upper electrode layer 5 of the photoelectric conversion cell 10 on the other end side.

  Next, each member of the photoelectric conversion unit 11 will be described. A plurality of lower electrode layers 2 are arranged on one main surface of the substrate 1 at intervals in one direction (X direction in FIG. 6). The number of lower electrodes 3 is not limited to that shown in FIG. Such a lower electrode layer 2 may be a thin film containing a metal such as Mo, Al, Ti, Ta or Au, or an alloy thereof. Moreover, the structure formed by laminating | stacking these metals may be sufficient. The lower electrode layer 2 may be formed to a thickness of about 0.2 to 1 μm on the substrate 1 by using a sputtering method or a vapor deposition method, for example.

The first semiconductor layer 3 is disposed on the lower electrode layer 2. For example, amorphous silicon or a compound semiconductor is used for the first semiconductor layer 3. Examples of the compound semiconductor include an I-III-VI compound, an I-II-IV-VI group compound semiconductor, and an II-VI group compound semiconductor.

An I-III-VI compound semiconductor is a compound of a group IB element (also referred to as a group 11 element), a group III-B element (also referred to as a group 13 element) and a group VI-B element (also referred to as a group 16 element). It is a semiconductor. Such an I-III-VI compound semiconductor has a chalcopyrite structure and is also called a chalcopyrite compound semiconductor (also referred to as a CIS compound semiconductor). Examples of the I-III-VI compound semiconductor include copper indium diselenide (CuInSe ₂ ), copper indium diselenide / gallium (Cu (In, Ga) Se ₂ ), diselen selenide / copper indium / gallium (gallium ( Cu (In, Ga) (Se, S) ₂ ), copper indium gallium disulfide (Cu (In, Ga) S ₂ ), or a thin film of selenium disulfide / copper indium / gallium as a surface layer There are multi-element compound semiconductor thin films such as copper indium selenide and gallium.

In addition, the I-II-IV-VI group compound semiconductors are IB group elements, II-B group elements (also referred to as group 12 elements), IV-B group elements (also referred to as group 14 elements), and VI-B. It is a compound semiconductor of a group element. Examples of the I-II-IV-VI group compound include Cu ₂ ZnSnS ₄ .

  The II-VI group compound semiconductor is a compound semiconductor of II-B group elements and VI-B group elements. Examples of II-VI group compound semiconductors include CdTe.

  The first semiconductor layer 3 is formed by a vacuum process such as sputtering or vapor deposition. The first semiconductor layer 3 is also formed by a process called a coating method or a printing method. In the application method or the printing method, for example, a complex solution of an element mainly contained in the first semiconductor layer 3 is applied on the lower electrode layer 2, and then drying and heat treatment are performed.

  The second semiconductor layer 4 is provided on the main surface on the + Z side of the first semiconductor layer 3 with a thickness of, for example, 10 to 200 nm, and has a conductivity different from the conductivity type of the first semiconductor layer 3. Mainly includes semiconductors with molds. Note that semiconductors having different conductivity types are semiconductors having different conductive carriers. For example, if the first semiconductor layer 3 is p-type, the second semiconductor layer 4 is n-type and vice versa. Further, another semiconductor layer such as i-type may be interposed between the first semiconductor layer 3 and the second semiconductor layer 4.

  The second semiconductor layer 4 may be formed by doping the surface portion of the first semiconductor layer 3 with another element, and is formed by heterojunction with a compound different from the first semiconductor layer 3. It may be.

  The upper electrode layer 5 is provided on the main surface on the + Z side of the second semiconductor layer 4. For example, the upper electrode layer 5 is a translucent conductive layer having the same conductivity type as that of the second semiconductor layer 4. The upper electrode layer 5 serves as an electrode for extracting carriers generated in the first semiconductor layer 3 and the second semiconductor layer 4. The upper electrode layer 5 mainly includes a material having a lower electrical resistivity than the second semiconductor layer 4.

The upper electrode layer 5 mainly includes a material having a wide forbidden bandwidth, a light transmitting property, and a low electrical resistance. Examples of such a material include zinc oxide (ZnO), a compound of zinc oxide, and metal oxide semiconductors such as indium oxide (ITO) containing tin and tin oxide (SnO ₂ ). The zinc oxide compound contains any one element of aluminum, boron, gallium, indium, and fluorine.

  The upper electrode layer 5 can be formed by sputtering, vapor deposition, chemical vapor deposition (CVD), or the like. The thickness of the upper electrode layer 5 is, for example, 0.05 to 3.0 μm. Here, if the upper electrode layer 5 has a resistivity of less than 1 Ω · cm and a sheet resistance of 50 Ω / □ or less, the first semiconductor layer 3 and the second semiconductor layer 3 are interposed via the upper electrode layer 5. Carriers can be taken out from the semiconductor layer 4 satisfactorily.

  If the thickness of the upper electrode layer 5 is 0.05 to 0.5 μm, the light transmissivity in the translucent conductive layer 6 can be improved, and at the same time, the current generated by the photoelectric conversion can be transmitted well. Furthermore, if the absolute refractive index of the upper electrode layer 5 and the absolute refractive index of the second semiconductor layer 4 are substantially the same, light is reflected at the interface between the upper electrode layer 5 and the second semiconductor layer 4. The resulting incident light loss can be reduced.

  The collecting electrode 6 is linearly provided on the + Z side main surface (also referred to as one main surface) of the upper electrode layer 5 from the end of the upper electrode layer 5 to the connection conductor 7. For example, the carriers collected by the upper electrode layer 5 of the photoelectric conversion cell 10 can be further collected by the current collecting electrode 6 and transmitted to the adjacent photoelectric conversion cell 10 via the connection conductor 7.

  By providing the current collecting electrode 6, the conductivity of the upper electrode layer 5 is supplemented, so that the upper electrode layer 5 can be thinned. Thereby, securing of the carrier extraction efficiency and improvement of light transmittance in the upper electrode layer 5 can both be achieved. If the current collecting electrode 6 mainly contains a metal having excellent conductivity such as silver, for example, the conversion efficiency in the photoelectric conversion cell 10 can be improved. In addition, as a metal contained in the current collection electrode 6, copper, aluminum, nickel, etc. are mentioned, for example.

  Moreover, if the width | variety of the current collection electrode 6 is 50-400 micrometers, the fall of the incident amount of the light to the 1st semiconductor layer 3 will be reduced, ensuring the favorable electroconductivity between the adjacent photoelectric conversion cells 10. FIG. obtain. When a plurality of collector electrodes 6 are provided in one photoelectric conversion cell 10, the interval between the plurality of collector electrodes 6 may be about 2.5 mm, for example.

  The connection conductor 7 is disposed in a separation groove that separates the first semiconductor layer 3 and the second semiconductor layer 4. The connection conductor 7 is electrically connected to the current collecting electrode 6. The connection conductor 7 is connected to the lower electrode layer 2 extended from the adjacent photoelectric conversion cell 10. Thereby, the connection conductor 7 can electrically connect the upper electrode layer 5 of one photoelectric conversion cell 10 and the lower electrode layer 2 of the other photoelectric conversion cell 10 among the adjacent photoelectric conversion cells 10.

  The connection conductor 7 may be made of the same material and method as the current collecting electrode 6. Therefore, the connection conductor 7 may be performed simultaneously with the formation of the current collecting electrode 6. Further, the connection conductor 7 may be obtained by extending the upper electrode layer 5.

<Photoelectric Conversion Module According to Second Embodiment>
The present invention is not limited to the above-described embodiment, and many modifications and changes can be made within the scope of the present invention. In the photoelectric conversion module 101 according to the first embodiment, the example in which the first wiring conductor 9 and the second wiring conductor 19 are connected on the output electrode 8 has been described, but the present invention is not limited to this. As shown in the photoelectric conversion module 201 according to the second embodiment of FIGS. 8 and 9, the first wiring conductor 29 and the second wiring conductor 39 are arranged outside the output electrode 8 on one main surface of the substrate 1. It may be connected in the area. With such a configuration, the highly conductive first wiring conductor 29 can be lengthened, and the electric power generated in the photoelectric conversion unit 11 can be extracted with little loss.

  The first wiring conductor 29 and the second wiring conductor 39 may be connected by soldering, adhesion with a conductive adhesive, welding, or the like. From the viewpoint of reducing the height of the surface of the second wiring conductor 39 from the surface of the first wiring conductor 29, the first wiring conductor 29 and the second wiring conductor 39 may be connected by welding. .

101, 201: photoelectric conversion module 1: substrate 11: photoelectric conversion unit 8: output electrode 9, 29: first wiring conductor 19, 39: second wiring conductor

Claims (10)

A substrate having a major surface;
A photoelectric conversion unit disposed on the one principal surface;
A strip-shaped output electrode extending in one direction, arranged to be electrically connected to the photoelectric conversion unit on the one main surface or the photoelectric conversion unit;
A strip-shaped wiring conductor that is electrically connected to the output electrode and is led to a back surface of the substrate through a through hole provided in the substrate or through a side surface of the substrate;
It comprises a sealing material that covers the photoelectric conversion part and the wiring conductor,
The wiring conductor has a first wiring conductor connected to the output electrode and a second wiring conductor led out from the one main surface to the back surface,
The photoelectric conversion module, wherein the surface portion of the second wiring conductor is more resistant to corrosion by moisture than the surface portion of the first wiring conductor. The photoelectric conversion module according to claim 1, wherein the surface portion of the second wiring conductor is made of a material capable of forming a passive state. The photoelectric conversion module according to claim 1, wherein the surface portion of the second wiring conductor has a lower ionization tendency than the surface portion of the first wiring conductor. 4. The photoelectric conversion module according to claim 1, wherein the first wiring conductor and the second wiring conductor are connected on the output electrode. 5.   In the connection portion between the first wiring conductor and the second wiring conductor, a part of the second wiring conductor is located on the first wiring conductor and the other of the second wiring conductor. The photoelectric conversion module according to claim 4, wherein a part of the photoelectric conversion module is connected to the output electrode.   The photoelectric conversion module according to claim 1, wherein the second wiring conductor includes a main body portion and a film that covers a surface of the main body portion.   The photoelectric conversion module according to claim 1, wherein the first wiring conductor is connected to the output electrode by welding.   The photoelectric conversion module according to claim 1, wherein the first wiring conductor and the second wiring conductor are connected by welding.   4. The photoelectric conversion module according to claim 1, wherein the first wiring conductor and the second wiring conductor are connected in a region outside the output electrode on the one main surface. 5.   The photoelectric conversion module according to claim 9, wherein the first wiring conductor is connected to the output electrode by welding.

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