JP2012160511A - Photoelectric conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion device whose conversion efficiency can be raised by an increase in amount of light incident to a light-receiving surface.SOLUTION: A photoelectric conversion device 20 comprises: a substrate 1; and a plurality of photoelectric conversion cells 10 which are aligned in a predetermined alignment direction on one principal plane of the substrate 1 with first gaps P3, and each of which has a photoelectric conversion layer 3. Each of the photoelectric conversion cells 10 includes: a power generation contributing part 10A; a power generation non-contributing part 10B which is arranged between each of the first gaps and each of second gaps P2 penetrating through the photoelectric conversion layer 3 in a direction perpendicular to the principal plane of the substrate 1; and a reflection member which is arranged on the power generation non-contributing part 10B. The photoelectric conversion device according to the present embodiment has resin materials 6 provided in the first gaps P3 and the second gaps P2.

Description

  The present invention relates to a photoelectric conversion device.

  As a photoelectric conversion device used for solar power generation or the like, there is one in which cells corresponding to a plurality of photoelectric conversion bodies are provided on one substrate. In this cell, for example, a lower electrode, a compound semiconductor thin film, a buffer layer, and a transparent electrode layer are laminated in this order. And the voltage output from a photoelectric conversion apparatus can be raised because an adjacent cell is electrically connected in series.

  This photoelectric conversion device is required to improve conversion efficiency. Therefore, even if the transparent electrode layer is thinned to improve the light transmission by providing a linear collector electrode made of metal wiring on the transparent electrode layer on the light receiving surface side, the charge generated in the cell Has been disclosed (for example, Patent Document 1).

JP 2002-37395 A

  However, the cell disclosed in Patent Document 1 has a non-power generation contribution portion between a groove portion where a transparent electrode layer that electrically connects adjacent cells is disposed and a groove portion between adjacent cells. To do. The light incident on the non-power generation contributing portion is reflected by the surface of the metal wiring and emitted to the outside. This can reduce the amount of light incident on the cell.

  Therefore, there is a demand for a photoelectric conversion device in which conversion efficiency can be increased by increasing the amount of light incident on the cell.

  A photoelectric conversion device according to an embodiment of the present invention includes a substrate and a plurality of photoelectric conversion layers having photoelectric conversion layers arranged in a predetermined arrangement direction with a first gap portion on one main surface of the substrate. And a conversion cell. In addition, the photoelectric conversion cell includes a power generation contributing portion, and a non-power generation provided between the second gap portion and the first gap portion that penetrates the photoelectric conversion layer in a direction perpendicular to one main surface of the substrate. And a reflecting member provided on the non-power generation contributing portion. In the photoelectric conversion device according to the present embodiment, a resin material is provided in the first gap portion and the second gap portion.

  According to the photoelectric conversion device according to one embodiment of the present invention, since the reflection member is provided on the non-power generation contributing portion, the light reflected by the reflection member is guided to the light receiving surface of the power generation contribution portion of the photoelectric conversion cell. obtain. As a result, the conversion efficiency in the photoelectric conversion device can be increased by increasing the amount of light incident on the photoelectric conversion cell. Moreover, in this embodiment, since the non-electric power generation contribution part in which the reflection member is provided is arrange | positioned between the 1st gap | interval part and the 2nd gap | interval part, it arises between a reflection member and a non-power generation contribution part. The influence of stress on the power generation contributing portion can be reduced. Therefore, in this embodiment, the reliability of the photoelectric conversion device can be improved.

It is a top view which shows typically the structure of the photoelectric conversion apparatus which concerns on one Embodiment of this invention. It is sectional drawing in the position shown with the dashed-dotted line II-II in FIG. It is sectional drawing in the position shown with the dashed-two dotted line III-III in FIG. It is the schematic diagram which showed the mode of the light which injects into the photoelectric conversion apparatus which concerns on one Embodiment. It is sectional drawing which shows typically the photoelectric conversion apparatus which concerns on other embodiment. It is sectional drawing which shows the mode in the middle of manufacture of the photoelectric conversion apparatus which concerns on one Embodiment. It is sectional drawing which shows the mode in the middle of manufacture of the photoelectric conversion apparatus which concerns on one Embodiment. It is sectional drawing which shows the mode in the middle of manufacture of the photoelectric conversion apparatus which concerns on one Embodiment. It is sectional drawing which shows the mode in the middle of manufacture of the photoelectric conversion apparatus which concerns on one Embodiment. It is sectional drawing which shows the mode in the middle of manufacture of the photoelectric conversion apparatus which concerns on one Embodiment. FIG. 2 illustrates a state in the middle of manufacturing of the photoelectric conversion device according to the embodiment, where (a) is a cross-sectional view at a position indicated by a one-dot chain line II-II in FIG. 1, and (b) is a two-dot chain line III in FIG. Sectional drawing in the position shown by -III. It is sectional drawing which shows typically the photoelectric conversion apparatus which concerns on a modification.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings, parts having the same configuration and function are denoted by the same reference numerals, and redundant description is omitted in the following description. Further, the drawings are schematically shown, and the sizes, positional relationships, and the like of various structures in the drawings are not accurately illustrated. 1 to 12 are provided with a right-handed XYZ coordinate system in which the arrangement direction of photoelectric conversion cells 10 (the horizontal direction in the drawing in FIG. 1) is the X-axis direction.

<(1) Schematic configuration of photoelectric conversion device>
<(1-1) Schematic configuration of photoelectric conversion device>
As shown in FIG. 1 or FIG. 2, the photoelectric conversion device 20 includes a substrate 1 and a plurality of photoelectric conversion cells 10 arranged in a plane on one main surface of the substrate 1. Adjacent photoelectric conversion cells 10 are separated by a separation groove P3 as a first gap. That is, in the photoelectric conversion device 20, a plurality of photoelectric conversion cells 10 are arranged on one main surface of the substrate 1 through the separation groove portion P <b> 3 along a predetermined arrangement direction (+ X direction in the present embodiment). In FIG. 1, the separation groove portion P <b> 1 is seen through the top surface for convenience of illustration, and is indicated by a dotted line. In FIG. 1, only a part of the three photoelectric conversion cells 10 is shown. However, in the photoelectric conversion device 20, a large number (for example, eight) of photoelectric conversion cells 10 may be arranged in a plane (two-dimensionally) in the horizontal direction of the drawing. For example, electrodes for obtaining a voltage and a current by power generation can be provided at both ends in the X-axis direction of the photoelectric conversion device 20. In the photoelectric conversion device 20, for example, a large number of photoelectric conversion cells 10 may be arranged in a matrix.

  Further, for example, a mode in which the shape of the upper surface of each photoelectric conversion cell 10 is approximately rectangular and the shape of the upper surface of the photoelectric conversion device 20 is approximately square may be employed. In addition, the shape of the upper surface of each photoelectric conversion cell 10 does not need to be substantially rectangular, and may be other shapes. Moreover, the shape of the upper surface of the photoelectric conversion device 20 does not have to be generally square, and may be other shapes. However, in the photoelectric conversion device 20, the conversion efficiency is improved if a large number of photoelectric conversion cells 10 are arranged in a high-density plane.

  The conversion efficiency indicates a rate at which sunlight energy is converted into electric energy in the photoelectric conversion device 20. For example, the conversion efficiency can be derived by dividing the value of the electric energy output from the photoelectric conversion device 20 by the value of the energy of sunlight incident on the photoelectric conversion device 20 and multiplying by 100.

<(1-2) Basic configuration of photoelectric conversion cell>
Each photoelectric conversion cell 10 includes a lower electrode 2, a photoelectric conversion layer 3, and an upper electrode 45. Each photoelectric conversion cell 10 is provided with a separation groove portion P1 and a separation groove portion P2 as a second gap portion. In the photoelectric conversion device 20, the main surface on the side where the upper electrode 45 is provided is a light receiving surface.

  The substrate 1 supports a plurality of photoelectric conversion cells 10. Examples of the main material included in the substrate 1 include glass, ceramics, resin, and metal. Here, the substrate 1 is assumed to be blue plate glass (soda lime glass) having a thickness of 1 mm or more and 3 mm or less.

  The lower electrode 2 is a conductive layer provided on one main surface of the substrate 1 on the + Z side. As the main material included in the lower electrode 2, various conductive metals such as molybdenum, aluminum, titanium, tantalum, and gold can be employed. The thickness of the lower electrode 2 is, for example, about 0.2 μm or more and about 1 μm or less. The lower electrode 2 can be formed by a known thin film forming method such as a sputtering method or a vapor deposition method.

  The photoelectric conversion layer 3 is provided on the lower electrode 2 and includes a light absorption layer 31 and a buffer layer 32 that are sequentially stacked. Since the light absorption layer 31 and the buffer layer 32 are layers mainly including a semiconductor, the photoelectric conversion layer 3 is a layer mainly including a semiconductor (also referred to as a semiconductor layer).

  The light absorption layer 31 is provided on a main surface (also referred to as one main surface) on the + Z side of the lower electrode 2 and mainly includes a semiconductor having a first conductivity type (here, p-type conductivity type). . The thickness of the light absorption layer 31 is, for example, about 1 μm to 3 μm. The light absorption layer 31 mainly includes, for example, an I-III-VI group compound semiconductor. Thereby, the light absorption layer 31 can be thinned, and the conversion efficiency can be increased at a low cost with a small amount of material. The I-III-VI group compound semiconductor is a semiconductor mainly containing an I-III-VI group compound.

Here, as the I-III-VI group compound, 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). ). Examples of the I-III-VI group compounds include CuInSe ₂ (also referred to as copper indium selenide, CIS), Cu (In, Ga) Se ₂ (also referred to as copper indium diselenide, gallium, CIGS), and Cu. A material such as (In, Ga) (Se, S) ₂ (also referred to as diselene, copper indium gallium sulfide, gallium, or CIGSS) may be employed. Here, the light absorption layer 31 shall mainly contain CIGS.

The light absorption layer 31 may be, for example, a thin film of a multicomponent compound semiconductor such as copper indium selenide / gallium having a thin film mainly containing diselen / copper indium sulfide / gallium as a surface layer. The light absorption layer 31 may mainly contain, for example, a II-VI group compound semiconductor. The II-VI group compound semiconductor is a semiconductor mainly containing a II-VI group compound. The II-VI group compound is a compound mainly containing a II-B group (also referred to as a group 12 element) and a VI-B group element. However, if the light absorption layer 31 mainly contains an I-III-VI compound semiconductor, the photoelectric conversion efficiency (also referred to as photoelectric conversion efficiency) in the photoelectric conversion layer 3 can be increased. Moreover, the light absorption layer 31 may be a CZTS-based material including, for example, copper (Cu), zinc (Zn), tin (Sn), and sulfur (S). An example of such a CZTS compound semiconductor is Cu ₂ ZnSnS ₄ . Since the CZTS compound semiconductor does not use rare metal unlike the I-III-VI compound semiconductor, it is easy to secure the material.

The light absorption layer 31 can be formed by a vacuum process such as sputtering or vapor deposition. The light absorption layer 31 can also be 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 elements mainly contained in the light absorption layer 31 is applied on the lower electrode 2, and then drying and heat treatment are performed. By using a process called this coating method or printing method, the cost for manufacturing the photoelectric conversion device 20 can be reduced.

  The buffer layer 32 is provided on the main surface (also referred to as one main surface) on the + Z side of the light absorption layer 31, and has a second conductivity type (here, n) different from the first conductivity type of the light absorption layer 31. Mainly including a semiconductor having a conductive type). Note that semiconductors having different conductivity types are semiconductors having different conductive carriers. Moreover, the conductivity type of the light absorption layer 31 may be n-type, and the conductivity type of the buffer layer 32 may be p-type. Here, a heterojunction region is formed between the light absorption layer 31 and the buffer layer 32. For this reason, in the photoelectric conversion cell 10, photoelectric conversion can occur in the light absorption layer 31 and the buffer layer 32 that form the heterojunction region.

The buffer layer 32 mainly includes a compound semiconductor. Examples of the compound semiconductor included in the buffer layer 32 include cadmium sulfide (CdS), indium sulfide (In ₂ S ₃ ), zinc sulfide (ZnS), zinc oxide (ZnO), indium selenide (In ₂ Se ₃ ), In (OH, S), (Zn, In) (Se, OH), (Zn, Mg) O, and the like may be employed. If the buffer layer 32 has a resistivity of 1 Ω · cm or more, the generation of leakage current can be suppressed. The buffer layer 32 can be formed by, for example, a chemical bath deposition (CBD) method or the like.

  The buffer layer 32 has a thickness in the normal direction of one main surface of the light absorption layer 31. This thickness is set to, for example, 10 nm or more and 200 nm or less. If the thickness of the buffer layer 32 is not less than 100 nm and not more than 200 nm, the buffer layer 32 is less likely to be damaged when the translucent conductive layer 4 is formed on the buffer layer 32 by a sputtering method or the like.

  The upper electrode 45 is provided on the + Z side main surface (also referred to as one main surface) of the buffer layer 32. The upper electrode 45 includes a translucent conductive layer 4 and a grid electrode portion 5.

  The translucent conductive layer 4 is provided on one main surface of the buffer layer 32 and is, for example, a transparent conductive layer (also referred to as a transparent conductive layer) having an n-type conductivity. The translucent conductive layer 4 serves as an electrode (also referred to as an extraction electrode) that extracts charges generated in the photoelectric conversion layer 3. The translucent conductive layer 4 mainly includes a material having a lower resistivity than the buffer layer 32. The translucent conductive layer 4 may include what is called a window layer, and may include a window layer and a transparent conductive layer.

The translucent conductive layer 4 mainly includes a material having a wide forbidden band, transparent, and low resistance. As such a material, for example, a metal oxide semiconductor such as zinc oxide (ZnO), a compound of zinc oxide, indium oxide containing tin (ITO), and tin oxide (SnO ₂ ) can be employed. The zinc oxide compound only needs to contain any one element of aluminum, boron, gallium, indium, and fluorine.

  The translucent conductive layer 4 can be formed by a sputtering method, a vapor deposition method, a chemical vapor deposition (CVD) method, or the like. The thickness of the translucent conductive layer 4 may be, for example, 0.05 μm or more and 3.0 μm or less. Here, if the translucent conductive layer 4 has a resistivity of less than 1 Ω · cm and a sheet resistance of 50 Ω / □ or less, the photoelectric conversion layer 3 charges from the translucent conductive layer 4. Can be taken out well.

If the buffer layer 32 and the light-transmitting conductive layer 4 have a property (also referred to as light transmittance) that allows light to easily pass through the wavelength band of light that can be absorbed by the light absorption layer 31, light absorption is achieved. A decrease in light absorption efficiency in the layer 31 can be suppressed. Further, when the thickness of the translucent conductive layer 4 is 0.05 μm or more and 0.5 μm or less, the light transmissivity in the translucent conductive layer 4 is improved and the current generated by photoelectric conversion is good. Can be transmitted. Further, if the absolute refractive index of the translucent conductive layer 4 and the absolute refractive index of the buffer layer 32 are substantially the same, the incidence caused by the reflection of light at the interface between the translucent conductive layer 4 and the buffer layer 32. Light loss can be reduced.

  The grid electrode portion 5 is a linear electrode portion (also referred to as a linear electrode portion) provided on the main surface (also referred to as one main surface) on the + Z side of the translucent conductive layer 4. The grid electrode part 5 includes a plurality of current collecting parts 5a, connecting parts 5b, and hanging parts 5c. The plurality of current collectors 5a are separated in the Y-axis direction, and each current collector 5a extends in the X-axis direction. The connecting portion 5b is provided in the Y-axis direction, and each current collecting portion 5a is connected. The hanging part 5c is connected to the lower part of the connecting part 5b, and is connected to the lower electrode 2 extended from the adjacent photoelectric conversion cell 10 through the separation groove part P2.

  The current collector 5 a plays a role of collecting charges generated in the photoelectric conversion layer 3 and taken out in the translucent conductive layer 4. By providing the current collector 5a, the conductivity of the translucent conductive layer 4 is supplemented, so that the translucent conductive layer 4 can be thinned. As a result, it is possible to achieve both the securing of the charge extraction efficiency and the improvement of the light transmissivity in the translucent conductive layer 4. In addition, if the grid electrode part 5 mainly contains the metal excellent in electroconductivity, such as silver, the conversion efficiency in the photoelectric conversion apparatus 20 can improve. Moreover, as a metal contained in the grid electrode part 5, copper, aluminum, nickel etc. may be sufficient, for example.

  The electric charges collected by the translucent conductive layer 4 and the plurality of current collecting portions 5a are transmitted to the adjacent photoelectric conversion cell 10 through the connecting portion 5b and the hanging portion 5c. Thereby, in the photoelectric conversion apparatus 20, the adjacent photoelectric conversion cells 10 are electrically connected in series. Specifically, the drooping portion 5c electrically connected to the current collector 5a of the upper electrode 45 of one photoelectric conversion cell 10 and the lower electrode 2 of the other photoelectric conversion cell 10 are electrically connected. Are connected in series.

  In addition, when the width of the current collector 5a is 50 μm or more and 400 μm or less, a decrease in the amount of light incident on the light absorption layer 31 is suppressed while ensuring good electrical conduction between the adjacent photoelectric conversion cells 10. Can be done. The interval between the plurality of current collectors 5a provided in one photoelectric conversion cell 10 may be about 2.5 mm, for example.

<(1-3) Arrangement of separation groove and its role>
The separation groove P1 extends linearly in the Y-axis direction. By providing one or more separation grooves P1, the plurality of lower electrodes 2 are separated in the X-axis direction. In FIG. 2, three lower electrodes 2 are shown. An extending portion of the light absorption layer 31 provided immediately above is embedded in the separation groove P1. Thereby, the lower electrode 2 of one adjacent photoelectric conversion cell 10 and the lower electrode 2 of the other photoelectric conversion cell 10 are electrically separated. The width of the separation groove portion P1 may be, for example, about 50 μm or more and about 400 μm or less, which is about the same as the width of the grid electrode portion 5.

  The separation groove portion P2 is provided from one main surface of the translucent conductive layer 4 to the upper surface of the lower electrode 2, and extends linearly in the Y-axis direction. For this reason, the separation groove portion P2 separates the stacked portion in which the photoelectric conversion layer 3 and the translucent conductive layer 4 are stacked in the X-axis direction. That is, the separation groove P2 is provided so as to penetrate the photoelectric conversion layer 3 in a direction perpendicular to one main surface of the substrate 1.

  The separation groove portion P3 is provided from the upper surface of the photoelectric conversion cell 10 to the upper surface of the lower electrode 2, and extends in the Y-axis direction. The width of the separation groove P3 may be, for example, about 40 μm or more and about 1000 μm or less.

  Moreover, the resin material 6 is arrange | positioned in the separation groove part P2 and the separation groove part P3. Further, in the separation groove portion P2, the resin material 6 is filled in a portion where the hanging portion 5c is not disposed. The resin material 6 may be disposed in a region other than the separation groove P2 (second gap) and the separation groove P3 (first gap). For example, if the resin material 6 is disposed so as to cover the upper electrode 45 on the light receiving surface of the photoelectric conversion cell 10, it is possible to mitigate external impacts and the like that act on the photoelectric conversion cell 10.

  As a material of the resin material 6, for example, an organic compound mainly composed of a transparent ethylene-vinyl acetate copolymer (EVA) or polyvinyl butyral (PVB) is used. Specifically, the organic compound is molded into a sheet shape having a thickness of about 0.4 to 1 mm, and the resin material is filled into the separation groove portion P2 and the separation groove portion P3 while thermosetting the sheet-like resin material. By this, the resin material 6 can be arrange | positioned to the separation groove part P2 and the separation groove part P3. The resin material 6 may contain a crosslinking agent. This cross-linking agent has a role of binding molecules such as EVA. As the crosslinking agent, for example, an organic peroxide that decomposes at a temperature of 70 ° C. to 180 ° C. to generate radicals can be used. Examples of the organic peroxide include 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane and tert-hexylperoxypivalate. Moreover, when using EVA for the resin material 6, you may contain a crosslinking agent in the ratio of about 1 mass part with respect to 100 mass parts of EVA. In addition to the above-mentioned EVA and PVB, any resin can be used as the resin material 6 as long as it is a thermosetting resin or a resin that contains a crosslinking agent in a thermoplastic resin and has thermosetting properties. Examples of such a resin include an acrylic resin, a silicone resin, an epoxy resin, and EEA (ethylene-ethyl acrylate copolymer).

  When the photoelectric conversion device 20 is viewed in plan from above the light receiving surface (here, + Z side), the separation groove P2 is provided between the separation groove P1 and the separation groove P3. In other words, the separation groove portion P1, the separation groove portion P2, and the separation groove portion P3 are provided in this order in the + X direction. Further, in each photoelectric conversion cell 10, the photoelectric conversion layer 3 is provided from above the lower electrode 2 to beyond the separation groove P <b> 1 and to the upper part of the adjacent lower electrode 2. Here, the adjacent lower electrode 2 is the lower electrode 2 extending from the adjacent photoelectric conversion cell 10.

  When the photoelectric conversion device 20 is seen through from above the light receiving surface (here, + Z side), the photoelectric conversion device 20 includes the separation groove portion P1 and the separation groove portion P2, and includes the separation groove portion P1 and the separation groove portion P2. There are a region sandwiched between (also referred to as a connection region), a region sandwiched between the separation groove P2 and the separation groove P3, and a remaining region. As shown in FIG. 3, this remaining region is a region contributing to power generation (also referred to as a power generation contributing region), and this is a power generation contributing portion 10 </ b> A of the photoelectric conversion cell 10. On the other hand, as shown in FIG. 3, a region sandwiched between the separation groove portion P2 and the separation groove portion P3 is a region that does not contribute to power generation (also referred to as a non-power generation contribution region), and this is a non-power generation contribution portion 10B of the photoelectric conversion cell 10. It becomes.

  In the photoelectric conversion layer 3 of the non-power generation contributing portion 10B, electrons and holes are generated when light is incident thereon, but an electromotive force is hardly generated by recombination at the adjacent hanging portion 5c. Therefore, the non-power generation contributing portion 10B is an area that cannot substantially contribute to photoelectric conversion that can generate power because it cannot substantially extract electrons (electric power) to the outside.

In the present embodiment, as shown in FIGS. 2 to 4, in the upper electrode 45 located on the non-power generation contributing portion 10 </ b> B, the connection in the direction perpendicular to one main surface of the substrate 1 (+ Z direction in FIG. 4). The thickness of the part 5b is larger than the thickness of the upper electrode 45 other than the connecting part 5b. In other words, the upper electrode 45 is formed with a convex portion protruding in the + Z direction on the non-power generation contributing portion 10B. Thereby, for example, as shown in FIG.
The light is reflected from the side surface of the connecting portion 5b protruding in the + Z direction from the upper surface (light receiving surface) of the photoelectric conversion cell 10, and is easily irradiated to the light receiving surface of the power generation contributing portion 10A of the adjacent photoelectric conversion cell 10. That is, the connecting part 5b plays a role as a reflecting member. Therefore, in this embodiment, the light that was scheduled to be incident on the surface of the non-power generation contributing portion 10B can be incident on the power generation contributing portion 10A. As a result, in this embodiment, the conversion efficiency in the photoelectric conversion device 20 can be increased by increasing the amount of light incident on the photoelectric conversion cell 10.

  In the present embodiment, as shown in FIG. 3 or FIG. 4, the non-power generation contributing portion 10B is located between the separation groove portion P2 (second gap portion) and the separation groove portion P3 (first gap portion). . Therefore, even if excessive stress is generated due to a difference in thermal expansion coefficient between the thick connecting portion 5b provided on the non-power generation contributing portion 10B and the photoelectric conversion layer 3 of the non-power generation contributing portion 10B, the separation groove portion It can be relaxed by the resin material 6 arranged in P2 and the separation groove P3. Therefore, in this embodiment, the stress mentioned above becomes difficult to act on the photoelectric conversion layer 3 of 10 A of electric power generation contribution parts. As a result, in the present embodiment, the reliability of the photoelectric conversion device 20 can be maintained even in an environment where the temperature change is severe.

  Moreover, in this embodiment, the effect as a reflection member is acquired only by changing the thickness in + Z direction of the connection part 5b as mentioned above. Therefore, in this embodiment, a reflection effect can be obtained without using a new reflection member.

  Furthermore, in this embodiment, a gold layer may be provided on the surface of the connecting portion 5b. Thereby, since the reflective effect in the connection part 5b increases more, the quantity of the light which injects into the electric power generation contribution part 10A of the photoelectric conversion cell 10 is increased more. Such a gold layer can be formed by, for example, a sputtering method or the like by placing a mask on a portion other than the connecting portion 5b. Further, the gold layer may contain a metal other than gold, for example, carbon, aluminum, nickel, copper, silver, or the like in an amount of about 0.01% by mass or less.

  Further, the connecting portion 5b may have a curved surface as shown in FIG. Thereby, the reflection effect of the light in the connection part 5b can be improved more. In particular, in such a form, for example, when a photoelectric conversion module is configured by providing a glass substrate above the light receiving surface of the photoelectric conversion device 20, light is reflected toward the surface of the glass substrate, It becomes easy to guide the light reflected again on the surface to the power generation contributing portion 10 </ b> A of the photoelectric conversion cell 10. As a result, with such a configuration, the conversion efficiency in the photoelectric conversion device 20 can be further increased by further increasing the amount of light incident on the photoelectric conversion cell 10.

  As shown in FIG. 5, the entire surface of the connecting portion 5b may be a curved surface (connecting portion 5b1), or a part of the surface may be a curved surface (connecting portion 5b2). In this connection part 5b1, the light re-incident to the photoelectric conversion cell 10 using the reflection in the surface of the glass substrate mentioned above is easy to be performed. On the other hand, in the connecting portion 5b2 having a flat side surface and a curved upper surface as shown in FIG. 5, light is incident on the power generation contribution portion 10A of the photoelectric conversion cell 10 by reflection of the side surface portion and reflection of the curved surface portion. Thus, light can be reincident on the power generation contribution portion 10A of the photoelectric conversion cell 10 via the surface of the glass substrate.

<(2) Manufacturing process of photoelectric conversion device>
Here, an example of a manufacturing process of the photoelectric conversion device 20 having the above configuration will be described. Hereinafter, a case where the light absorption layer 31 mainly including the I-III-VI group compound semiconductor is formed by using a coating method or a printing method and the buffer layer 32 is further formed will be described as an example. 6 to 11 are XZ cross-sectional views schematically showing a state in the process of manufacturing the photoelectric conversion device 20.

<(2-1) Formation of Lower Electrode 2>
First, as shown in FIG. 6, the lower electrode 2 mainly containing Mo or the like is formed on substantially the entire main surface of the cleaned substrate 1 by using a sputtering method or the like.

<(2-2) Formation of Separation Groove P1>
Next, a linear separation groove P <b> 1 is formed from a predetermined formation target position on the upper surface of the lower electrode 2 to the upper surface of the substrate 1 immediately below it. FIG. 7 is a view showing a state after the separation groove portion P1 is formed. The separation groove P1 can be formed, for example, by irradiating a predetermined formation target position while scanning with a YAG laser or other laser light.

<(2-3) Formation of photoelectric conversion layer 3>
Next, the light absorption layer 31 and the buffer layer 32 are sequentially formed on the lower electrode 2 to form the photoelectric conversion layer 3. FIG. 8 is a diagram illustrating a state after the photoelectric conversion layer 3 is formed.

  Here, the light absorption layer 31 can be formed by applying a predetermined solution to the surface of the lower electrode 2 and then sequentially performing drying and heat treatment. The predetermined solution can be prepared, for example, by dissolving a group IB metal and a group III-B metal directly in a solvent (also referred to as a mixed solvent) containing a chalcogen element-containing organic compound and a basic organic solvent. . In the predetermined solution, for example, the total concentration of the group I-B metal and the group III-B metal can be 10 wt% or more. As a method for applying the predetermined solution, various methods such as spin coater, screen printing, dipping, spraying, and die coater can be adopted.

  The chalcogen element-containing organic compound is an organic compound containing a chalcogen element. The chalcogen elements are sulfur, selenium, and tellurium among the VI-B group elements. As the chalcogen element-containing organic compound, for example, thiol, sulfide, disulfide, selenol, selenide, diselenide and the like can be employed.

  Here, for example, as a method for forming the light absorbing layer 31, a method in which the following steps (i) to (iii) are mainly performed in order may be employed. (i) A mixed solvent is prepared by dissolving benzeneselenol so as to be 100 mol% with respect to pyridine. (ii) In this mixed solvent, the copper of the bare metal, the indium of the bare metal, the gallium of the bare metal, and the selenium of the bare metal are directly dissolved to prepare a solution. (iii) This solution is applied to the surface of the lower electrode 2 by a blade method, and then dried to form a film. The film is subjected to heat treatment in an atmosphere of hydrogen gas.

  In addition, the process in which a metal is directly dissolved in a mixed solvent is a process in which a simple metal or an alloy metal is directly mixed and dissolved in a mixed solvent. Drying may be performed, for example, in a reducing atmosphere. The drying temperature may be, for example, 50 ° C. or higher and 300 ° C. or lower. If the heat treatment is performed in a reducing atmosphere, oxidation of the film is reduced and a good I-III-VI group compound semiconductor can be obtained. The reducing atmosphere may be any one of, for example, a nitrogen atmosphere, a hydrogen atmosphere, and a mixed gas atmosphere of hydrogen and nitrogen or argon. The heat processing temperature should just be 400 degreeC or more and 600 degrees C or less, for example.

  The buffer layer 32 is formed by a solution growth method (CBD method). For example, the buffer layer 32 mainly containing CdS is formed by immersing the substrate 1 in which the light absorption layer 31 has been formed in a solution prepared by dissolving cadmium acetate and thiourea in ammonia. Can be formed.

<(2-4) Formation of translucent conductive layer 4>
Next, the translucent conductive layer 4 is formed on the photoelectric conversion layer 3. FIG. 9 is a view showing a state after the translucent conductive layer 4 is formed. The translucent conductive layer 4 can be formed by sputtering, vapor deposition, chemical vapor deposition (CVD), or the like. For example, the transparent translucent conductive layer 4 mainly including zinc oxide to which aluminum is added is formed on the buffer layer 32.

<(2-5) Formation of Separation Groove P2>
Next, the separation groove P <b> 2 is formed in a region from the predetermined formation target position to the upper surface of the lower electrode 2 in the upper surface of the translucent conductive layer 4. FIG. 10 is a diagram illustrating a state after the separation groove portion P2 is formed. The separation groove portion P2 can be formed by mechanical scribing using a scribe needle. Note that the separation groove portion P2 may be formed by a laser beam in the same manner as the separation groove portion P1.

<(2-6) Formation of grid electrode portion 5>
Next, the grid electrode part 5 is formed from a predetermined formation target position on the upper surface of the translucent conductive layer 4 in which the separation groove part P2 is formed to the inside of the separation groove part P2. FIGS. 11A and 11B are views showing a state after the grid electrode portion 5 is formed.

  The grid electrode portion 5 is printed so that, for example, a metal paste in which a metal powder such as silver is dispersed in a resin binder or the like has the current collecting portion 5a and the connecting portion 5b, and the printed metal paste is dried. It can be formed by solidifying. At this time, the metal paste also enters the separation groove portion P2 and solidifies by drying, whereby the hanging portion 5c of the grid electrode portion 5 is formed. Solidification here means solidification after melting when the binder contained in the metal paste is a thermoplastic resin, and solidification by curing when the binder is a curable resin such as a thermosetting resin or a photocurable resin. And are included.

  Here, the connection part 5b of the grid electrode part 5 (upper electrode 45) is printed so that thickness becomes larger than another site | part. As this method, for example, the number of times of printing of the portion of the connecting portion 5b may be increased more than other portions. As another method, the metal paste may be printed more than other portions by slowing down the speed of the squeegee when printing the connecting portion 5b. Thereby, the thickness of the connection part 5b of the grid electrode part 5 in the + Z direction which is a direction perpendicular to one main surface of the substrate 1 is larger than the thickness of the other grid electrode part 5 part such as the current collecting part 5a. Become. In the metal paste printing process, printing may be performed once, or may be performed twice or more.

  As the metal paste, a paste having a silver content of 85 wt% or more and 98 wt% or less and a resin component content of 2 wt% or more and 15 wt% or less can be adopted. For example, when the silver content in the metal paste is 88 wt% or more and 92 wt% or less, viscosity suitable for printing and good conductivity can be obtained.

<(2-7) Formation of Separation Groove P3>
After the grid electrode portion 5 is formed, the separation groove portion P3 is formed in a region from the predetermined formation target position to the upper surface of the lower electrode 2 on the upper surface of the translucent conductive layer 4. Thereby, the photoelectric conversion apparatus 20 shown by FIGS. 1-4 is obtained. The separation groove part P3 can be formed by mechanical scribing using a scribe needle, like the separation groove part P2. At this time, the edge part of the grid electrode part 5 may be slightly shaved off.

<(2-8) Filling of resin material>
After the separation groove portion P3 is formed, the resin material 6 is disposed in the space portion where the hanging portion 5c of the separation groove portion P2 is not disposed and the separation groove portion P3. First, a sheet material of about 0.4 to 1 mm made of a resin material mainly composed of ethylene vinyl acetate copolymer (EVA) is prepared. Next, the sheet material is arranged on the upper surface of the photoelectric conversion cell 10. Then, using a laminator device etc., 120
The sheet material is pressure-bonded to the photoelectric conversion cell while the sheet material is thermoset while being heated to about 150 ° C. to 150 ° C. Thus, the resin material 6 is formed by filling the separation groove portion P2 and the separation groove portion P3 with a part of the sheet material.

<(3) Modification>
In the embodiment described above, the connecting portion 5b functions as a reflecting member by increasing the thickness of the connecting portion 5b of the upper electrode 45 in the + Z direction. However, the present invention is not limited to such a form. For example, instead of the connecting portion 5b, a reflecting member such as the reflecting mirror 7 may be provided on the non-power generation contributing portion 10B as shown in FIG. The shape of the reflection mirror 7 is, for example, as shown in FIG. 12, a section having a concave lens shape and a section having a trapezoidal shape. In the trapezoidal reflection mirror 7, the light reflected by the light receiving surface of the power generation contributing portion 10A can be incident again on the light receiving surface of the power generation contributing portion 10A.

  As the reflection mirror 7, for example, an aluminum base provided with a metal layer such as silver or gold can be used. Further, if the reflection mirror 7 is formed of a conductive material and is connected to the current collector 5a, the resistance value of the upper electrode 45 can be reduced. Such a reflection mirror 7 is bonded onto the non-power generation contributing portion 10B with, for example, an epoxy resin adhesive containing conductive metal particles.

  It should be noted that the present invention is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the gist of the present invention.

1: Substrate 2: Lower electrode 3: Photoelectric conversion layer 31: Light absorption layer 32: Buffer layer 4: Translucent conductive layer 5: Grid electrode portion 5a: Current collecting portion 5b, 5b1, 5b2: Connection portion 5c: Hanging portion 6: Resin material 7: Reflection mirror 10: Photoelectric conversion cell 10A: Power generation contributing portion 10B: Non-power generation contributing portion 20: Non-photoelectric conversion layer 30: Photoelectric conversion device 45: Upper electrode P1: Separation groove P2: Separation groove (second Gap)
P3: Separation groove (first gap)

Claims (5)

A substrate,
A plurality of photoelectric conversion cells having photoelectric conversion layers arranged in a predetermined arrangement direction with a first gap portion on one main surface of the substrate;
The photoelectric conversion cell includes a power generation contribution portion and a non-power generation contribution portion provided between the second gap portion and the first gap portion that penetrate the photoelectric conversion layer in a direction perpendicular to one main surface of the substrate. And a reflection member provided on the non-power generation contributing portion,
A photoelectric conversion device in which a resin material is provided in the first gap and the second gap. The photoelectric conversion cell further includes an upper electrode provided on the photoelectric conversion layer,
The upper electrode has a plurality of current collectors and a connecting part for connecting the current collectors,
The photoelectric conversion device according to claim 1, wherein the connecting portion is included in the reflecting member. The plurality of photoelectric conversion cells further include a lower electrode provided between one main surface of the substrate and the photoelectric conversion layer,
The upper electrode has a hanging portion that electrically connects the current collector of one of the photoelectric conversion cells and the lower electrode of the other photoelectric conversion cell, and the hanging portion has the second gap. The photoelectric conversion device according to claim 2, wherein the photoelectric conversion device is located in a portion.   The photoelectric conversion device according to claim 2, wherein the connecting portion is provided with a gold layer on a surface thereof.   The photoelectric conversion device according to claim 2, wherein a surface of the connecting portion is curved.

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