JP2015026642A - Photoelectric conversion device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve photoelectric conversion efficiency of a photoelectric conversion device by decreasing electric resistance between photoelectric conversion cells.SOLUTION: A photoelectric conversion device 11 includes: a substrate 1; a first lower electrode layer 2a and a second lower electrode layer 2b spaced from each other and disposed in one direction on the substrate 1; a photoelectric conversion layer PE disposed from above the first lower electrode layer 2a to above the second lower electrode layer 2b; a conductive film 5 that has a first portion 5a covering an upper surface of the photoelectric conversion layer PE, a second portion 5b connected to the first portion 5a and covering a side face of the photoelectric conversion layer PE, and a third portion 5c connected to the second portion 5b and covering a part of the second lower electrode layer 2b; and an auxiliary conductor 6 that is disposed in a range from a surface of the second portion 5b by way of a surface of the third portion 5c to a portion of an upper surface of the second electrode layer 2b not covered with the conductive film 5.

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, electrical resistance between the photoelectric conversion cells is large, 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 by reducing the electrical resistance between photoelectric conversion cells.

  A photoelectric conversion device according to one embodiment of the present invention includes a substrate, a first lower electrode layer and a second lower electrode layer that are spaced apart from each other and disposed in one direction, and the first lower electrode layer. A photoelectric conversion layer disposed from the electrode layer to the second lower electrode layer, a first portion covering the upper surface of the photoelectric conversion layer, connected to the first portion and a side surface of the photoelectric conversion layer A conductive film having a second part to be covered and a third part that is connected to the second part and covers a part of the second lower electrode layer; and a surface of the third part from a surface of the second part. And an auxiliary conductor disposed over a portion of the upper surface of the second lower electrode layer not covered with the conductive film.

  According to the present invention, it is possible to reduce power loss caused by photoelectric conversion and increase photoelectric conversion efficiency.

1 is a perspective view of a photoelectric conversion device according to a first embodiment. It is sectional drawing of the photoelectric conversion apparatus of FIG. It is a top view of the photoelectric conversion apparatus of FIG. It is a perspective view of the photoelectric conversion apparatus which concerns on 2nd Embodiment.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

<Configuration of Photoelectric Conversion Device According to First Embodiment>
FIG. 1 is a perspective view showing an example of a photoelectric conversion apparatus according to the first embodiment of the present invention, and FIG. 2 is a sectional view thereof. FIG. 3 is a plan view of the photoelectric conversion device of FIG. 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. 1 to 3 have a right-handed XYZ coordinate system in which the X-axis direction is the direction in which the photoelectric conversion cells 10 are arranged (the horizontal direction in the drawing in FIG. 1). 1 to 3 show only two photoelectric conversion cells 10a and 10b for convenience of illustration, but in the actual photoelectric conversion device 11, in the X-axis direction of the drawing, or further in the Y-axis direction, A large number of photoelectric conversion cells 10 may be arranged two-dimensionally (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). A photoelectric conversion layer PE is provided. A conductive film 5 is provided from the upper surface of the photoelectric conversion layer PE through the side surface to the second lower electrode layer 2b. The conductive film 5 includes a first part 5a that covers the upper surface of the photoelectric conversion layer PE, a second part 5b that is connected to the first part 5a and covers the side surface of the photoelectric conversion layer PE, and the second part 5b. And a third portion 5c that covers a part of the second lower electrode layer 2b. The auxiliary conductor extends from the surface of the second portion 5b of the conductive film 5 to the portion of the upper surface of the second lower electrode layer 2b that is not covered by the conductive film 5 (third portion 5c) through the surface of the third portion 5c. 6 is provided.

  One photoelectric conversion cell 10 is composed of the first lower electrode layer 2, the photoelectric conversion layer PE, and the first portion 5a functioning as the upper electrode layer. And the 1st site | part 5a of one photoelectric conversion cell 10a in the adjacent photoelectric conversion cell 10 and the 2nd lower electrode layer 2b of the other photoelectric conversion cell 10b are the 2nd site | part 5b, the 3rd site | part 5c, and auxiliary | assistant. It is electrically connected by the conductor 6, and with such a configuration, the photoelectric conversion device 11 in which the adjacent photoelectric conversion cells 10 are connected in series is obtained. Here, the 2nd site | part 5b, the 3rd site | part 5c, and the auxiliary conductor 6 function as a connection conductor for electrically connecting adjacent photoelectric conversion cell 10a, 10b.

  Since the connection conductor is constituted by the second portion 5b, the third portion 5c, and the auxiliary conductor 6 as described above, the electrical connection between the adjacent photoelectric conversion cells 10a and 10b is high in connection reliability. The power loss can be low. As a result, the photoelectric conversion efficiency of the photoelectric conversion device 11 is increased. That is, the second part 5b and the third part 5c are formed so as to be continuous with the first part 5a functioning as the upper electrode layer of the photoelectric conversion cell 10a, and thereby the first part 5a and the second lower part are formed. The electrical connection with the electrode layer 2b is highly reliable. On the other hand, the auxiliary conductor 6 is connected to the second part 5b and the third part and has a part directly connected to the second lower electrode layer 2b without going through the third part 5c. The power loss can be reduced by lowering the electrical resistance of the connecting conductor connecting the first portion 5a and the second lower electrode layer 2b.

  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 4 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.

  The photoelectric conversion layer PE is a semiconductor layer having a thickness of about 0.5 to 5 μm, for example. As the photoelectric conversion layer PE, one that can satisfactorily separate electrons and holes generated by light irradiation is used. For example, the surface of one conductivity type semiconductor layer is doped with an impurity element to change the surface to the other conductivity type. Or a semiconductor layer in which the other conductive type semiconductor layer is stacked on the one conductive type semiconductor layer. The one conductivity type and the other conductivity type may be the other conductivity type if the one conductivity type is p type, and vice versa. In the present embodiment, an example is shown in which the photoelectric conversion layer PE is formed by laminating a first semiconductor layer 3 of one conductivity type (p type) and a second semiconductor layer 4 of the other conductivity type (n type).

The material of the first semiconductor layer 3 is not particularly limited, and metal chalcogenide, amorphous silicon, or the like can be used. From the viewpoint of having a relatively high photoelectric conversion efficiency, for example, I-III
Metal chalcogenides such as a -VI group compound, an I-II-IV-VI group compound, and a II-VI group compound may be used as the material of the first semiconductor layer 3.

An I-III-VI group compound is a group 11 element (also referred to as a group IB element), a group 13 element (also referred to as a group III-B element), and a group 16 element (also referred to as a VI-B group 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 selenide / copper indium sulfide / gallium 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 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 5 to 200 nm by, for example, a chemical bath deposition (CBD) method or a sputtering 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.

  The conductive film 5 is a layer having a lower electrical resistivity than the second semiconductor layer 4 and has a function of favorably extracting charges generated in the photoelectric conversion layer PE. From the viewpoint of further increasing the photoelectric conversion efficiency, the electrical resistivity of the conductive film 5 may be less than 1 Ω · cm and the sheet resistance may be 50 Ω / □ or less.

The conductive film 5 is a thin film having a thickness of about 0.05 to 3 μm thinner than the photoelectric conversion layer PE, and can be formed by a thin film forming method such as a sputtering method, a vapor deposition method, or a chemical vapor deposition (CVD) method. For the conductive film 5, for example, a metal oxide semiconductor such as ZnO, In ₂ O ₃ and SnO ₂ can be adopted. These metal oxide semiconductors may contain any element of Al, B, Ga, In, F, and the like. Specific examples of the metal oxide semiconductor containing such an element include, for example, AZO (Aluminum Zinc Oxide), GZO (Gallium Zinc Oxide), IZO (Indium Zinc Oxide), ITO (Indium Tin Oxide), FTO ( Fluorine
tin Oxide).

  The conductive film 5 has a first part 5a, a second part 5b, and a third part 5c. As shown in FIG. 3, the third portion 5c is formed in a strip shape on the second lower electrode layer 2b along the photoelectric conversion layer PE, and exposes a part of the second lower electrode layer 2b. Yes.

  The conductive film 5 having the first part 5a, the second part 5b, and the third part 5c can be manufactured as follows. First, after forming the photoelectric conversion layer PE on the lower electrode layer 2, a part of the photoelectric conversion layer PE is removed by mechanical scribe processing or laser scribe processing, and the second portion 5b, the third portion 5c, and the auxiliary conductor 6 are removed. A groove portion P for forming is formed. Then, the conductive film 5 is formed on the photoelectric conversion layer PE and on the inner surface of the groove P (on the side surface of the photoelectric conversion layer PE and the lower electrode layer 2 exposed by cutting the photoelectric conversion layer PE) by a thin film forming method. . Thereafter, a part of the conductive film 5 formed on the lower electrode layer 2 in the groove P is removed by mechanical scribe processing or laser scribe processing, and the lower electrode layer 2 is exposed, whereby the first portion 5a, Two sites 5b and a third site 5c can be formed.

  Mechanical scribing is a processing method of cutting an object with a needle-like processing tool or a drill. Laser scribing is a processing method for removing an object by irradiating a laser beam.

  1-3, the auxiliary conductor 6 is not covered with the third portion 5c on the upper surface of the second lower electrode layer 2b from the surface of the second portion 5b through the surface of the third portion 5c. It is provided over. The auxiliary conductor 6 can be formed 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 heating it.

  The area of the auxiliary conductor 6 connected to the second lower electrode layer 2b across the third portion 5c is directly connected to the second lower electrode layer 2b without the third portion 5c interposed therebetween. It can be about 0.3 to 10 times the area of the part.

  1 to 3, the auxiliary conductor 6 includes a plurality of sub auxiliary conductors 6a to 6c, and the plurality of sub auxiliary conductors 6a to 6c are orthogonal to the arrangement direction (X-axis direction) of the photoelectric conversion cells 10a and 10b. Are arranged along the direction (Y-axis direction). With such a configuration, light is easily incident on the photoelectric conversion layer PE from between the auxiliary auxiliary conductors while improving the electrical connection between the adjacent photoelectric conversion cells 10a and 10b. Will improve. In addition, the space | interval of sub-auxiliary conductors can be 1-5 mm, for example.

As shown in FIGS. 1 to 3, a current collecting electrode 8 that extends in a strip shape and is connected to the auxiliary conductor 6 may be further provided on the upper surface of the first portion 5 a. The current collecting electrode 8 is for further increasing the conductivity of the first portion 5a. In the case where the photoelectric conversion device 11 is configured to be used so that light enters the photoelectric conversion layer PE through the first portion 5a, the viewpoint of increasing the light transmittance to the photoelectric conversion layer PE and having good conductivity. Therefore, the collector electrode 8 is 50
It may have a width of ˜400 μm. The current collecting electrode 8 may have a plurality of branched portions.

  The current collecting electrode 8 can be 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 heating it.

<Configuration of Photoelectric Conversion Device According to Second Embodiment>
In the above-described embodiment, the example in which the auxiliary conductor 6 includes the plurality of sub auxiliary conductors 6a to 6c has been described. However, the embodiment is not limited thereto. For example, as in the photoelectric conversion device 21 according to the second embodiment in FIG. 4, the auxiliary conductor 26 may be formed to extend in a strip shape in the Y direction along the photoelectric conversion layer PE. In addition, in the photoelectric conversion apparatus 21 which concerns on 2nd Embodiment of FIG. 4, the same code | symbol is attached | subjected to the thing of the same structure as the photoelectric conversion apparatus 11 which concerns on 1st Embodiment, and detailed description is abbreviate | omitted. With such a configuration, it is possible to further reduce the electrical resistance of the connection conductor formed by the second portion 5b, the third portion 5c, and the auxiliary conductor 26. That is, the power loss between the adjacent photoelectric conversion cells 20a and 20b can be further reduced, and the photoelectric conversion efficiency of the photoelectric conversion device 21 can be further increased.

  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.

1: substrate 2: lower electrode layer 2a: first lower electrode layer 2b: second lower electrode layer PE: photoelectric conversion layer 3: first semiconductor layer 4: second semiconductor layer 5: conductive film 5a: first 1 part 5b: 2nd part 5c: 3rd part 6, 26: Auxiliary conductor 6a, 6b, 6c: Sub auxiliary conductor 8: Current collecting electrode 10, 20: Photoelectric conversion cell 11, 21: Photoelectric conversion device

Claims (4)

A substrate,
A first lower electrode layer and a second lower electrode layer disposed on the substrate in a direction spaced apart from each other;
The photoelectric conversion layer disposed from above the first lower electrode layer to the second lower electrode layer, a first portion covering the upper surface of the photoelectric conversion layer, connected to the first portion and the photoelectric conversion layer A conductive film having a second part covering the side surface of the conversion layer and a third part connected to the second part and covering a part of the second lower electrode layer;
A photoelectric conversion device comprising: an auxiliary conductor disposed from a surface of the second part through a surface of the third part to a part of the upper surface of the second lower electrode layer that is not covered with the conductive film.   2. The photoelectric conversion device according to claim 1, wherein the auxiliary conductor includes a plurality of sub auxiliary conductors, and the plurality of sub auxiliary conductors are arranged at intervals from each other along a direction orthogonal to the one direction.   3. The photoelectric conversion device according to claim 1, further comprising a collecting electrode extending in a strip shape and connected to the auxiliary conductor on the first portion. 4.   The photoelectric conversion device according to claim 1, wherein the third portion extends in a strip shape along the photoelectric conversion layer.

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