JP2013110341A - Photoelectric conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the photoelectric conversion efficiency of a photoelectric conversion device.SOLUTION: A photoelectric conversion device 11 comprises: a substrate 1; a first lower-electrode layer 2a and a second lower-electrode layer 2b that are provided on the substrate 1 so as to be spaced apart from each other; a first semiconductor layer 3 that is provided on the first lower-electrode layer 2a and has a first conductivity type; a second semiconductor layer 4 that is provided on the first semiconductor layer 3 and has a second conductivity type different from the first conductivity type; a connection conductor 7 that electrically connects the second lower-electrode layer 2b and the second semiconductor layer 4; and an insulating member 6 that is interposed between the first lower-electrode layer 2a and the second lower-electrode layer 2b.

Description

  The present invention relates to a photoelectric conversion device in which a plurality of photoelectric conversion cells are electrically connected.

  As a photoelectric conversion device used for solar power generation or the like, there is one in which a plurality of photoelectric conversion cells are provided on a substrate (for example, Patent Document 1).

  In such a photoelectric conversion device, a photoelectric conversion cell in which a lower electrode layer such as a metal electrode, a light absorption layer, a buffer layer, and a transparent conductive film are laminated in this order on a substrate such as glass is a flat surface. Thus, a plurality of them are arranged side by side. The plurality of photoelectric conversion cells are electrically connected in series by connecting the transparent conductive film of one adjacent photoelectric conversion cell and the other lower electrode layer with a connection conductor.

JP 2000-299486 A

  A photoelectric conversion device is always required to improve photoelectric conversion efficiency. In the photoelectric conversion device, as one method for increasing the photoelectric conversion efficiency, it is conceivable to reduce the interval between the lower electrode layers to increase the area of the part contributing to the photoelectric conversion. However, if the distance between the lower electrode layers is reduced, a leak current is likely to occur between adjacent lower electrode layers, and it is difficult to sufficiently increase the photoelectric conversion efficiency.

  One object of the present invention is to improve the photoelectric conversion efficiency of a photoelectric conversion device.

  A photoelectric conversion device according to an embodiment of the present invention includes a substrate, a first lower electrode layer and a second lower electrode layer provided on the substrate with a space therebetween, and the first lower electrode layer. A first semiconductor layer having a first conductivity type provided thereon, and a second semiconductor having a second conductivity type different from the first conductivity type provided on the first semiconductor layer A connecting conductor electrically connecting the second lower electrode layer and the second semiconductor layer, and an insulating member interposed between the first lower electrode layer and the second lower electrode layer It is characterized by comprising.

  According to the present invention, the leakage current between adjacent lower electrode layers can be reduced and the photoelectric conversion efficiency can be improved.

It is a perspective view which shows an example of embodiment of a photoelectric conversion apparatus. It is sectional drawing of the photoelectric conversion apparatus of FIG. FIG. 2 is a top perspective view of the photoelectric conversion device of FIG. 1. It is a perspective view which shows the other example of embodiment of a photoelectric conversion apparatus. It is sectional drawing of the photoelectric conversion apparatus of FIG.

  Hereinafter, a photoelectric conversion device according to an embodiment of the present invention will be described in detail with reference to the drawings.

<Configuration of photoelectric conversion device>
FIG. 1 is a perspective view illustrating an example of a photoelectric conversion apparatus according to an embodiment of the present invention, and FIG. FIG. 3 is a perspective view of the photoelectric conversion device of FIG. 1 viewed from the upper surface side. In the photoelectric conversion device 11, a plurality of photoelectric conversion cells 10 are arranged on the substrate 1 and are electrically connected to each other. Although only two photoelectric conversion cells 10 are shown in FIGS. 1 to 3 for the sake of illustration, in the actual photoelectric conversion device 11, there are many photoelectric conversion cells 10 in the horizontal direction of the drawing or in a direction perpendicular thereto. The photoelectric conversion cells 10 may be arranged in a plane (two-dimensionally).

  1 to 3, a plurality of lower electrode layers 2 are arranged in a plane on a substrate 1. Among the adjacent lower electrode layers 2, one upper electrode layer 2 a (hereinafter also referred to as the first lower electrode layer 2 a) to the other lower electrode layer 2 b (hereinafter also referred to as the second lower electrode layer 2 b). The first semiconductor layer 3 and the second semiconductor layer 4 having a conductivity type different from that of the first semiconductor layer 3 are provided. A connection conductor 7 is provided on the second lower electrode layer 2 b so as to electrically connect the second lower electrode layer 2 b and the second semiconductor layer 4. By including at least the lower electrode layer 2 (the first lower electrode layer 2a and the second lower electrode layer 2b), the first semiconductor layer 3, the second semiconductor layer 4, and the connection conductor 7, one photoelectric A conversion cell 10 is configured. Adjacent photoelectric conversion cells 10 are electrically connected by the second lower electrode layer 2b. With such a configuration, the adjacent photoelectric conversion cells 10 are connected in series to form a photoelectric conversion device 11. .

  In addition, although the photoelectric conversion apparatus 11 in this embodiment assumes what light injects with respect to the 1st semiconductor layer 3 from the 2nd semiconductor layer 4 side, it is not limited to this, The board | substrate 1 The light may be incident from the side.

  The substrate 1 is for supporting the photoelectric conversion cell 10. Examples of the material used for the substrate 1 include glass, ceramics, resin, and metal. As the substrate 1, for example, blue plate glass (soda lime glass) having a thickness of about 1 to 3 mm can be used.

  The lower electrode layer 2 (the first lower electrode layer 2a and the second lower electrode layer 2b) is a conductor such as Mo, Al, Ti, or Au provided on the 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 distance between the first lower electrode layer 2a and the second lower electrode layer 2b can be set to 20 to 200 μm, for example.

  An insulating member 6 is interposed between the first lower electrode layer 2a and the second lower electrode layer 2b. The insulating member 6 is a material having a higher resistivity than the first semiconductor layer 3 described later. As the insulating member 6, for example, one having a resistivity of 1 to 1000 Ω · cm or more can be used.

  By providing such an insulating member 6, it is possible to reduce a leakage current between the first lower electrode layer 2a and the second lower electrode layer 2b. Therefore, the space | interval of the site | part which contributes to the photoelectric conversion of a photoelectric conversion cell can be enlarged by making the space | interval of 1st lower electrode layer 2a and 2nd lower electrode layer 2b small. As a result, the photoelectric conversion efficiency of the photoelectric conversion device 11 is increased.

Examples of the insulating member 6 include glass such as silicate glass and quartz glass, inorganic compounds such as silica, alumina, and titania, and organic resins such as polyimide. The insulating member 6 is formed between the first lower electrode layer 2a and the second lower electrode layer 2b after the first lower electrode layer 2a and the second lower electrode layer 2b are formed on the substrate 1. For example, it is formed by using a sputtering method, a sol-gel method, a coating method, or the like. Alternatively, after the insulating member 6 is formed in a desired pattern shape on the substrate 1, the first lower electrode layer 2a and the second lower electrode layer 2b may be formed.

  The insulating member 6 may include a plurality of particles that reflect the light absorbed by the first semiconductor layer 3 as the light absorption layer. Or when the 2nd semiconductor layer 4 functions as a light absorption layer, the insulating member 6 may contain the some particle | grains which reflect the light which the 2nd semiconductor layer 4 absorbs. With such a configuration, light that travels toward the substrate 1 without being used can be reflected toward the first semiconductor layer 3 or the second semiconductor layer 4, and the photoelectric conversion efficiency of the photoelectric conversion device 11 is higher. Become.

  As the insulating member 6 including particles that reflect the light absorbed by the first semiconductor layer 3 or the second semiconductor layer 4 as described above, for example, particles such as white silica are dispersed in glass or an organic resin. Can be employed.

  The insulating member 6 may have a structure having a plurality of holes. In the case of having holes as described above, light can be favorably reflected by the difference in refractive index between the insulating member 6 and the holes and guided to the first semiconductor layer 3 or the second semiconductor layer 4 side. The conversion efficiency can be further increased. The insulating member 6 having such holes can be formed using, for example, a sol-gel method.

The first semiconductor layer 3 is a first conductivity type semiconductor layer. In the present embodiment, the first semiconductor layer 3 is assumed to be a p-type semiconductor layer having a thickness of, for example, about 1 μm to 3 μm, but is not limited thereto. The material of the first semiconductor layer 3 is not particularly limited, and metal chalcogenide, amorphous silicon, or the like can be used. In view of having a relatively high photoelectric conversion efficiency, for example, metal chalcogenides such as I-III-VI group compounds, I-II-IV-VI group compounds, and II-VI group compounds are materials for the first semiconductor layer 3. May be used as

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. By electrically connecting the first semiconductor layer 3 and the second semiconductor layer 4, a photoelectric conversion layer capable of taking out charges well is formed. For example, if the first semiconductor layer 3 is p-type, the second semiconductor layer 4 is n-type. The first semiconductor layer 3 may be n-type and the second semiconductor layer 4 may be p-type. A high-resistance buffer layer may be interposed between the first semiconductor layer 3 and the second semiconductor layer 4. Further, the first semiconductor layer 3 and the second semiconductor layer 4 as the light absorption layer may have opposite configurations, and the second semiconductor layer 4 and the first semiconductor layer are formed on the lower electrode layer 2. 3 may be laminated in order.

  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 it is possible to take out charges generated in the first semiconductor layer 3 and the second semiconductor layer 4 satisfactorily. 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.

  In addition, as shown in FIGS. 1 to 3, a collector electrode 8 may be further formed on the upper electrode layer 5. The current collecting electrode 8 is for taking out charges generated in the first semiconductor layer 3 and the second semiconductor layer 4 more satisfactorily. For example, as shown in FIGS. 1 to 3, the collector electrode 8 is formed in a linear shape from one end of the photoelectric conversion cell 10 to the connection conductor 7. As a result, the current generated in the first semiconductor layer 3 and the fourth semiconductor layer 4 is collected to the current collecting electrode 8 via the upper electrode layer 5, and to the adjacent photoelectric conversion cell 10 via the connection conductor 7. Good conductivity.

  The collector electrode 8 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 8 may have a plurality of branched portions.

  The collector electrode 8 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.

  1 and 2, the connection conductor 7 is a conductor provided in a groove that penetrates the first semiconductor layer 3, the second semiconductor layer 4, and the second electrode layer 5. The connection conductor 7 can be made of metal, conductive paste, or the like. In FIG. 1 and FIG. 2, the collector electrode 8 is extended to form the connection conductor 7, but this is not limitative. For example, the upper electrode layer 5 may be stretched.

<Other examples of photoelectric conversion device>
In the said one Embodiment, although the insulating member 6 was formed with the same thickness as the lower electrode layer 2, it is not restricted to this. For example, as shown in FIGS. 4 and 5, the insulating member 26 may be thicker than the lower electrode layer 2. 4 is a perspective view of a photoelectric conversion device 21 as another example, and FIG. 5 is a cross-sectional view of the photoelectric conversion device 21. 4 and 5, the same components as those in FIGS. When the insulating member 26 is thicker than the lower electrode layer 2 as shown in FIGS. 4 and 5, the leakage current between the connection conductor 7 and the first lower electrode layer 2 a can be reduced, and the photoelectric conversion of the photoelectric conversion device 21 is performed. Efficiency is further improved.

  The photoelectric conversion device 21 shown in FIGS. 4 and 5 is manufactured as follows, for example. First, the lower electrode layer 2 is formed in a desired pattern shape on the substrate 1, and the first semiconductor layer 3 is formed thereon. Then, the first semiconductor layer 3 corresponding to the gap between the first lower electrode layer 2a and the second lower electrode layer 2b is removed from the upper surface to the lower surface. The insulating member 26 is filled in the space where the first semiconductor layer 3 is removed. In such a method, the insulating member 26 may be formed after the first semiconductor layer 3 is heat-treated at a high temperature. Therefore, the heat resistance of the insulating member 26 is relatively limited, and the insulating member 26 is formed. The range of selection of 26 materials is widened.

  The insulating member 26 is the 1st semiconductor layer 3 or the 2nd semiconductor layer 4 from a viewpoint of raising the photoelectric conversion efficiency of the photoelectric conversion apparatus 21, like the insulating member 6 in the photoelectric conversion apparatus 11 shown in FIGS. It may include a plurality of particles that reflect the light that is absorbed.

  In addition, the insulating member 26 may have a structure having a plurality of holes from the viewpoint of increasing the photoelectric conversion efficiency of the photoelectric conversion device 21 in the same manner as the insulating member 6 in the photoelectric conversion device 11 shown in FIGS. Good.

  When the insulating member 26 is thicker than the first lower electrode layer 2, the insulating member 26 is formed from the first semiconductor layer 3 or the second semiconductor from the viewpoint of reducing the incidence of light from an oblique direction. The structure which permeate | transmits the light which the layer 4 absorbs may be sufficient.

  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, although the example in which the insulating member 6 is provided so as to contact the first lower electrode layer 2a and the second lower electrode layer 2b has been shown, the insulating member 6 includes the first lower electrode layer 2a and the second lower electrode layer 2b. It may be provided in a part between the lower electrode layers 2b, and may not be in contact with either one or both of the first lower electrode layer 2a and the second lower electrode layer 2b.

1: Substrate 2: Lower electrode layer 2a: First lower electrode layer 2b: Second lower electrode layer 3: First semiconductor layer 4: Second semiconductor layer 5: Upper electrode layer 6, 26: Insulating member 7 : Connection conductor 8: Current collecting electrode 10, 20: Photoelectric conversion cell 11, 21: Photoelectric conversion device

Claims (5)

A substrate,
A first lower electrode layer and a second lower electrode layer provided on the substrate at a distance from each other; and a first semiconductor having a first conductivity type provided on the first lower electrode layer Layers,
A second semiconductor layer having a second conductivity type different from the first conductivity type provided on the first semiconductor layer;
A connection conductor for electrically connecting the second lower electrode layer and the second semiconductor layer;
A photoelectric conversion device comprising: an insulating member interposed between the first lower electrode layer and the second lower electrode layer.   The photoelectric conversion device according to claim 1, wherein the insulating member is thicker than the first lower electrode layer.   The photoelectric conversion device according to claim 2, wherein the insulating member transmits light absorbed by the first semiconductor layer or the second semiconductor layer.   The photoelectric conversion device according to claim 1, wherein the insulating member includes a plurality of particles that reflect light absorbed by the first semiconductor layer or the second semiconductor layer.   The photoelectric conversion device according to claim 1, wherein the insulating member has a plurality of pores.

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