JP2014082297A - Photoelectric conversion module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the photoelectric conversion efficiency in a photoelectric conversion device.SOLUTION: A photoelectric conversion module 200 includes: a first substrate 1; a photoelectric conversion layer positioned on the first substrate 1; a translucent sealing material 20 which is positioned on an area ranging from the photoelectric conversion layer to the first substrate 1; a translucent second substrate 12 positioned on the sealing material 20; a sealant 21 which is positioned at the outer side of the sealing material 20 and closes a gap between the first substrate 1 and the second substrate 12; and a light reflection part 22 positioned between the sealing material 20 and the sealant 21.

Description

  The present invention relates to a photoelectric conversion module in which a photoelectric conversion layer is sealed with a sealing material.

  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.

  There are various types of photoelectric conversion modules used for photovoltaic power generation. Among them, those using a compound semiconductor thin film such as CIS (copper indium selenide) or CIGS (copper indium gallium selenide), or a thin film photoelectric conversion layer such as an amorphous silicon thin film, Research and development are being promoted because a large-area photoelectric conversion module can be easily manufactured at low cost.

  The thin film photoelectric conversion module includes a photoelectric conversion device in which a lower electrode layer, a photoelectric conversion layer, and an upper electrode layer are sequentially formed on a first substrate such as a glass substrate. Further, in such a photoelectric conversion module, a second substrate made of white tempered glass or the like is laminated on the above photoelectric conversion device via a sealing material such as ethylene vinyl acetate copolymer (hereinafter referred to as EVA). It is integrated.

  Moreover, in such a photoelectric conversion module, when moisture permeates from the outside, the photoelectric conversion layer and the like may deteriorate, and the photoelectric conversion efficiency may decrease. Therefore, in such a photoelectric conversion module, a sealing material for blocking moisture is disposed on the outer peripheral portion (see, for example, Patent Document 1).

JP 2007-123725 A

  The photoelectric conversion module is always required to improve the photoelectric conversion efficiency. As one method for increasing the photoelectric conversion efficiency, it is effective to efficiently guide the light incident on the photoelectric conversion module to the photoelectric conversion layer.

  This invention is made | formed in view of the said subject, and aims at the improvement of the photoelectric conversion efficiency in a photoelectric conversion apparatus.

  A photoelectric conversion module according to an embodiment of the present invention includes a first substrate, a photoelectric conversion layer positioned on the first substrate, and a translucent seal positioned on the first substrate from the photoelectric conversion layer. A sealing material, a translucent second substrate positioned on the sealing material, a sealing material positioned outside the sealing material and blocking a gap between the first substrate and the second substrate, A light reflecting portion positioned between the sealing material and the sealing material;

  According to the photoelectric conversion module according to the embodiment of the present invention, the photoelectric conversion efficiency of the photoelectric conversion module is improved.

It is a principal part expansion perspective view which shows the photoelectric conversion apparatus in the photoelectric conversion module which concerns on one Embodiment. It is sectional drawing of the photoelectric conversion apparatus of FIG. It is a perspective view showing the whole photoelectric conversion module concerning one embodiment. It is sectional drawing of the photoelectric conversion module of FIG. It is sectional drawing of the photoelectric conversion module which concerns on a 1st modification. It is sectional drawing of the photoelectric conversion module which concerns on a 2nd modification.

  Hereinafter, a photoelectric conversion module according to an embodiment of the present invention will be described in detail 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 6 have right-handed XYZ coordinates with the X-axis being the arrangement direction of photoelectric conversion cells, which will be described later. First, a photoelectric conversion device that is a part of the photoelectric conversion module will be described.

<Configuration of photoelectric conversion device>
FIG. 1 is an enlarged perspective view of a main part of the photoelectric conversion device 11, and FIG. 2 is an XZ sectional view thereof. The photoelectric conversion device 11 includes a plurality of photoelectric conversion cells 10 arranged along the X-axis direction. The photoelectric conversion cell 10 includes a first substrate 1, a lower electrode layer 2, a first semiconductor layer 3 having a first conductivity type, and a second conductivity type that is different from the first conductivity type. The semiconductor layer 4 and the upper electrode layer 5 are sequentially stacked. For example, if the first conductivity type is p-type, the second conductivity type is n-type, and vice versa. These first semiconductor layer 3 and second semiconductor layer 4 form a photoelectric conversion layer capable of separating charges well.

  In the photoelectric conversion device 11, the upper electrode layer 5 of one adjacent photoelectric conversion cell 10 and the lower electrode layer 2 of the other photoelectric conversion cell 10 are electrically connected via a connection conductor 6. With such a configuration, adjacent photoelectric conversion cells 10 are connected in series. And in the edge part of the photoelectric conversion apparatus 11, the extraction electrode 2a electrically connected with one electrode of the photoelectric conversion cell 10 connected in series is provided, The exterior of the photoelectric conversion apparatus 11 is provided in this extraction electrode 2a. A wiring conductor 13a for electrical connection is connected. Similarly, an extraction electrode 2b electrically connected to the other electrode of the photoelectric conversion cell 10 connected in series is provided at the opposite end of the photoelectric conversion device 11, and photoelectric conversion is performed on the extraction electrode 2b. A wiring conductor 13b for electrical connection with the outside of the device 11 is connected.

  1 and 2, only two photoelectric conversion cells 10 are shown for convenience of illustration, but an actual photoelectric conversion device 11 has an X-axis direction in the drawing or a Y-axis direction in the drawing. In addition, a large number of photoelectric conversion cells 10 are arranged in a plane (two-dimensionally).

  The first substrate 1 is for supporting the photoelectric conversion layer. Examples of the material used for the first substrate 1 include glass, ceramics, resin, and metal. As the first substrate 1, for example, blue plate glass (soda lime glass) having a thickness of about 1 to 3 mm may be used.

  The lower electrode layer 2 (lower electrode layers 2 a to 2 d) is a conductor such as Mo, Al, Ti, or Au provided on the first substrate 1. The lower electrode layer 2 is formed to a thickness of about 0.2 μm to 1 μm using a known thin film forming method such as sputtering or vapor deposition.

  The first semiconductor layer 3 is a semiconductor layer having the first conductivity type. The first semiconductor layer 3 has a thickness of about 1 μm to 3 μm, for example. The material of the first semiconductor layer 3 is not particularly limited, and a thin film semiconductor layer such as a compound semiconductor thin film or an amorphous silicon thin film is used. From the viewpoint of having a relatively high photoelectric conversion efficiency, for example, an I-III-VI group compound, an I-II-IV-VI group compound, an II-VI group compound or the like is used as the first semiconductor layer 3. Also good.

An I-III-VI group compound is a group consisting 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). A compound. Examples of the I-III-VI group compound include CuInSe ₂ (also referred to as copper indium selenide, CIS), Cu (In, Ga) Se ₂ (also referred to as copper indium selenide / gallium, CIGS), Cu ( In, Ga) (Se, S) ₂ (also referred to as diselene, copper indium sulphide, gallium, or CIGSS). Alternatively, the first semiconductor layer 3 may be composed of a multi-component compound semiconductor thin film such as copper indium selenide / gallium having a thin film of selenite / copper indium sulfide / gallium layer as a surface layer. The I-III-VI group compound has a relatively high light absorption coefficient, and good photoelectric conversion efficiency can be obtained even if the first semiconductor layer 3 is thin.

The I-II-IV-VI group compound includes an IB group element, an II-B group element (also referred to as a group 12 element), an IV-B group element (also referred to as a group 14 element), and a VI-B group element. It is a compound semiconductor. Examples of the I-II-IV-VI group compound include Cu ₂ ZnSnS ₄ (also referred to as CZTS) and Cu ₂ ZnSnS _4-x Se _x (also referred to as CZTSSe. Note that x is a number greater than 0 and smaller than 4. And Cu ₂ ZnSnSe ₄ (also referred to as CZTSe).

  The II-VI group compound is a compound semiconductor of a II-B group element and a VI-B group element. CdTe etc. are mentioned as a II-VI group compound.

  The second semiconductor layer 4 is a semiconductor layer having a second conductivity type different from that of the first semiconductor layer 3. The second semiconductor layer 4 may be formed by stacking a material different from that of the first semiconductor layer 3 on the first semiconductor layer 3, or the surface portion of the first semiconductor layer 3 may be other than the first semiconductor layer 3. It may be modified by elemental doping.

The second semiconductor layer 4 includes CdS, ZnS, ZnO, In ₂ S ₃ , In ₂ Se ₃ , In (OH, S), (Zn, In) (Se, OH), and (Zn, Mg) O. Etc. In this case, the second semiconductor layer 4 is formed with a thickness of 10 to 200 nm by, for example, a chemical bath deposition (CBD) method. In (OH, S) refers to a compound mainly containing In, OH, and S. (Zn, In) (Se, OH) refers to a compound mainly containing Zn, In, Se, and OH. (Zn, Mg) O refers to a compound mainly containing Zn, Mg and O.

  As shown in FIGS. 1 and 2, an upper electrode layer 5 may be further provided on the second semiconductor layer 4. The upper electrode layer 5 is a layer having a lower resistivity than the second semiconductor layer 4, and carriers generated in the first semiconductor layer 3 and the second semiconductor layer 4 are extracted well. From the viewpoint of further increasing the photoelectric conversion efficiency, the resistivity of the upper electrode layer 5 may be less than 1 Ω · cm and the sheet resistance may be 50 Ω / □ or less.

  The upper electrode layer 5 is a 0.05 to 3 μm transparent conductive film such as ITO or ZnO. In order to improve translucency and conductivity, the upper electrode layer 5 may be composed of a semiconductor having the same conductivity type as the second semiconductor layer 4. The upper electrode layer 5 can be formed by sputtering, vapor deposition, chemical vapor deposition (CVD), or the like.

  Further, as shown in FIGS. 1 and 2, a collecting electrode 7 may be further formed on the upper electrode layer 5. The current collecting electrode 7 is for taking out the carriers generated in the first semiconductor layer 3 and the second semiconductor layer 4 more satisfactorily. For example, as shown in FIG. 1, the collector electrode 7 is formed in a linear shape from one end of the photoelectric conversion cell 10 to the connection conductor 6. As a result, the current generated in the first semiconductor layer 3 and the fourth semiconductor layer 4 is collected by the current collecting electrode 7 via the upper electrode layer 5, and is supplied to the adjacent photoelectric conversion cell 10 via the connection conductor 6. Good conductivity.

  The collector electrode 7 may have a width of 50 to 400 μm from the viewpoint of increasing the light transmittance to the first semiconductor layer 3 and having good conductivity. The current collecting electrode 7 may have a plurality of branched portions.

  The collector electrode 7 is formed, for example, by printing a metal paste in which a metal powder such as Ag is dispersed in a resin binder or the like in a pattern and curing it.

  In FIGS. 1 and 2, the connection conductor 6 is a conductor provided in a groove that penetrates (divides) the first semiconductor layer 3, the second semiconductor layer 4, and the second electrode layer 5. The connection conductor 6 can be made of metal, conductive paste, or the like. In FIG. 1 and FIG. 2, the collector electrode 7 is extended to form the connection conductor 6, but the present invention is not limited to this. For example, the upper electrode layer 5 may be stretched.

<Configuration of photoelectric conversion module>
Next, the photoelectric conversion module will be described in detail. FIG. 3 is a perspective view showing the entire photoelectric conversion module 200 according to one embodiment, and FIG. 4 is a cross-sectional view thereof.

  The photoelectric conversion module 200 includes a light-transmitting second substrate 12 via a light-transmitting sealing material 20 on the photoelectric conversion device 11 illustrated in FIGS. 1 and 2. In addition, a sealing material 21 that closes the gap between the first substrate 1 and the second substrate 12 is provided outside the sealing material 20. Further, a light reflecting portion 22 is provided between the sealing material 20 and the sealing material 21.

  With such a configuration, light incident on the inside of the photoelectric conversion module 200 via the second substrate 12 can be efficiently guided to the light absorption layer 3 on the photoelectric conversion device 11, and the photoelectric conversion efficiency of the photoelectric conversion module 200 Can be increased. That is, the light that has traveled to the end portion of the sealing material 20 through the second substrate can be favorably reflected by the light reflecting portion 22 and can be favorably advanced to the light absorbing layer 3.

  The sealing material 20 is for protecting the photoelectric conversion cell 10 and is provided from the photoelectric conversion cell 10 to the first substrate 1. Moreover, the sealing material 20 has translucency with respect to the light which the light absorption layer 3 absorbs. Examples of such a sealing material 20 include a resin mainly composed of ethylene vinyl acetate copolymer (EVA) and a resin mainly composed of polyvinyl butyral.

  The sealing material 21 is provided along the side surface of the sealing material 20 so as to surround the periphery of the sealing material 20. In the example of FIG. 4, in the outer peripheral portion of the photoelectric conversion module 200, The gap with the second substrate 12 is filled.

  The sealing material 21 is for reducing moisture from entering the photoelectric conversion cell 10, and a member having a moisture permeability lower than that of the sealing material 20 is used. As such a sealing material 21, a resin such as polyethylene, an elastic body made of rubber such as butyl rubber or ethylene propylene rubber, or a mixture of the above-described resin and rubber can be used.

Further, as the sealing material 21, a polymer material in which an adsorbent is dispersed may be used. As such an adsorbent, those having the property of chemically adsorbing moisture may be used, or those having the property of physically adsorbing moisture may be used. The adsorbent that chemically adsorbs moisture has a property of chemically adsorbing with moisture and chemical reaction. For example, calcium oxide (CaO), sodium oxide (Na ₂ O), magnesium oxide (MgO), chloride calcium (CaCl _2), anhydrous sodium sulfate _(Na 2 _SO 4), and the like copper sulfate anhydrous salt (CuSO ₄₎ or calcium sulfate (CaSO _4). An adsorbent that physically adsorbs moisture adsorbs moisture by van der Waals force generated between the surface of the adsorbent and moisture. For example, molecular sieves such as zeolite, silica gel (SiO ₂ .nH ₂ O), inorganic materials having a porous surface such as alumina, allophane or activated carbon.

  The light reflecting portion 22 is provided between the sealing material 20 and the sealing material 21 so as to surround the periphery of the sealing material 20. In order to reflect the light that is going to travel from the sealing material 20 to the sealing material 21 side and to make it easier to travel to the photoelectric conversion cell 10 side, the light reflecting unit 22 is light of a wavelength used for photoelectric conversion in the photoelectric conversion device 11. On the other hand, a light reflectance of 20% or more can be used. Examples of such a light reflecting portion 22 include light reflecting metal members such as gold, silver, nickel, palladium, and platinum, and white members such as silica and titania.

  When the light reflection part 22 is a metal member, the light reflection part 22 arrange | positions the metal member shape | molded by the rod shape etc. between the sealing material 20 and the sealing material 21, for example, and the sealing material 20 and a sealing material 21 can be produced by heat curing. Or after forming the sealing material 20, you may produce by plating to the side surface of the sealing material 20. FIG. Moreover, when the light reflection part 22 is a white member, after forming the sealing material 20, the light reflection part 22 forms films | membranes, such as a silica and a titania, on the side surface of the sealing material 20 by the sol-gel method etc., for example. Can be produced.

  Moreover, the light reflection part 22 may be a translucent member in which metal particles or white particles are dispersed. For example, a translucent member such as a resin in which light-reflective metal particles such as gold, silver, nickel, palladium, platinum, or white particles such as silica or titania are dispersed is used. Good. Thereby, while improving adhesiveness with a translucent member, a reflectance can be improved with a metal particle or a white particle.

  In the photoelectric conversion module 200, the wiring conductors 13a and 13b are electrically connected to the extraction electrode portions 2a and 2b on the photoelectric conversion device 11, respectively. Further, as shown in FIG. 3, the other end of the wiring conductors 13 a and 13 b is led out to the back surface through a hole 1 a penetrating the first substrate 1 in the vertical direction, and the back surface (non- It is connected to a terminal box arranged on the light receiving surface. Then, the electric power generated by the photoelectric conversion module 200 is output to an external circuit through this terminal box.

  For the wiring conductors 13a and 13b, for example, a metal foil such as copper (Cu) having a thickness of about 0.1 to 0.5 mm and a width of about 1 to 7 mm is used. Also. The surface of the metal foil may be coated with tin, nickel, solder, or the like by plating or the like in order to improve electrical connection with the extraction electrode portions 2a, 2b.

<First Modification of Photoelectric Conversion Module>
Next, a modification of the photoelectric conversion module of the present invention will be described. FIG. 5 is a cross-sectional view showing a first modification of the photoelectric conversion module. In the photoelectric conversion module 300 shown in FIG. 5, the same reference numerals as those in FIG. 4 are given to parts having the same configuration and functions as those of the photoelectric conversion module 200 shown in FIG. 4 described above. In the photoelectric conversion module 300, the interface between the sealing material 20 and the light reflecting portion 32 is inclined so as to be separated from the photoelectric conversion layer (photoelectric conversion cell 10) as the distance from the first substrate 1 is increased. If it is such a structure, the light reflected in the interface of the sealing material 20 and the light reflection part 32 will advance easily to the photoelectric conversion cell 10 side, and a photoelectric conversion efficiency will become higher.

  Although FIG. 5 shows an example in which the interface between the sealing material 31 and the light reflecting portion 32 is inclined in the same direction, the present invention is not limited to this.

<Second Modification of Photoelectric Conversion Module>
FIG. 6 is a cross-sectional view showing a second modification of the photoelectric conversion module. In the photoelectric conversion module 400 shown in FIG. 6, the same reference numerals as those in FIG. 4 are given to portions having the same configuration and functions as those of the photoelectric conversion module 200 shown in FIG. 4 described above. The photoelectric conversion module 400 is provided so that the sealing member 41 covers the side surface of the first substrate 1 and the side surface of the second substrate 12, and the light reflecting portion 42 is provided between the sealing member 41 and the sealing material 20. Is provided. With such a configuration, it is possible to further reduce moisture from entering the photoelectric conversion cell 10.

  Note that the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the scope of the present invention. For example, in each structure of FIG. 4 and FIG. 5, the sealing materials 21 and 31 may be extended so that the side surface of the 1st board | substrate 1 and the 2nd board | substrate 12 may be covered.

1: First substrate 2: Lower electrode layer 3: First semiconductor layer 4: Second semiconductor layer 5: Upper electrode layer 10: Photoelectric conversion cell 11: Photoelectric conversion device 12: Second substrate 20: Sealing material 21 , 31, 41: Sealing material 22, 32, 42: Light reflection part 200, 300, 400: Photoelectric conversion module

Claims (4)

A first substrate;
A photoelectric conversion layer located on the first substrate;
A light-transmitting sealing material positioned over the photoelectric conversion layer and the first substrate;
A translucent second substrate located on the encapsulant;
A sealing material located outside the sealing material and closing a gap between the first substrate and the second substrate;
A photoelectric conversion module comprising a light reflecting portion positioned between the sealing material and the sealing material.   The photoelectric conversion module according to claim 1, wherein the light reflecting portion is a metal member or a white member.   The photoelectric conversion module according to claim 1, wherein the light reflecting portion is a translucent member including metal particles or white particles.   4. The photoelectric conversion module according to claim 1, wherein an interface between the sealing material and the light reflecting portion is inclined so as to be separated from the photoelectric conversion layer as being separated from the first substrate. 5.

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