TW201635571A - Photoelectric conversion element and photoelectric conversion device including the same - Google Patents

Abstract

To provide a photoelectric conversion element having excellent characteristics and a photoelectric conversion device including the same. The photoelectric conversion element of a roughly tabular shape includes: a substrate, a first electrode layer, a power generation layer, and a second electrode layer in this order. The second electrode layer is formed so that a side thereof is positioned inside of a side face position of the power generation layer over an entire circumference.

Description

Photoelectric conversion element and photoelectric conversion device using same Technical field

The present invention relates to a photoelectric conversion element having good characteristics and a photoelectric conversion device used after electrically connecting the same.

Background technique

In the related art, a photoelectric conversion device having a plurality of substrates, a first electrode layer, a power generation layer, and a second electrode layer is used, and solder is used in a state in which the edges of adjacent photoelectric conversion elements are overlapped with each other. The isoelectric connector (see, for example, Patent Document 1). This makes it possible to obtain a practical voltage by electrically connecting a plurality of photoelectric conversion elements.

However, the photoelectric conversion element using such a photoelectric conversion device generally has the configuration shown in Fig. 7(a), and each layer including the power generation layer 3 is extremely thin. Therefore, as shown in FIG. 7(b), when the end portion of the power generation layer 3 is short, the second electrode layer 4 is easily bent in the direction of the reverse white arrow, and the second electrode layer 4 is in contact with the first electrode layer 2, resulting in photoelectricity. The conversion element is shorted. Further, during or after the production of the photoelectric conversion element, the conductive dust adheres to the first electrode layer 2 and the second electrode layer 4, and the photoelectric conversion element is also short-circuited. Even if there is one photoelectric conversion element that generates a short circuit, the entire voltage of the photoelectric conversion device will be generated. As it falls, the occurrence of a short circuit in the photoelectric conversion element also becomes a big problem in the photoelectric conversion device.

Prior technical literature Patent literature

Patent Document 1: Japanese Patent Laid-Open Publication No. 2012-134342

Summary of invention

The present invention has been made in view of such circumstances, and an object thereof is to provide a photoelectric conversion element and a photoelectric conversion device using the same, which can effectively prevent a short circuit caused by a shortage of a power generation layer end portion or a fine conductive dust adhesion.

In order to achieve the above object, the present invention has the following first aspect of the invention: a photoelectric conversion element having a substantially plate shape and having at least a substrate, a first electrode layer, a power generation layer, and a second electrode layer, and the second electrode The entire circumference of the side of the layer is formed to be located further inside than the side surface of the power generation layer.

In the present invention, a photoelectric conversion device having a photoelectric conversion device having a plurality of photoelectric conversion elements and having adjacent edges of the photoelectric conversion elements superposed on each other and electrically connected thereto, each of the photoelectric conversion elements described above The photoelectric conversion element according to the first aspect has a substantially plate shape and has at least a substrate, a first electrode layer, a power generation layer, and a second electrode layer, and the entire surface of the side surface of the second electrode layer is formed to be located closer to the side surface of the power generation layer. More inside position.

In other words, the present inventors have repeatedly reviewed various methods for effectively preventing short-circuiting of the photoelectric conversion element causing the voltage drop in order to obtain a high-quality photoelectric conversion device. As a result, it has been found that an excellent short-circuit prevention effect can be obtained by processing the side portions of the photoelectric conversion elements in which the layers are laminated, and the present invention has been completed.

Further, in the present invention, the outline of the plate is visible to the extent that it is plate-shaped. Therefore, it is not necessary to have a uniform thickness as a whole, and it is only necessary to consider the concept of a plate as a whole.

In other words, the photoelectric conversion element of the present invention has a plate-like shape and has at least a substrate, a first electrode layer, a power generation layer, and a second photoelectric conversion element, and the entire surface of the second electrode layer is formed in the same manner as described above. The side of the power generation layer is disposed at the inner side. Therefore, even if a shortage occurs at the end portion of the power generation layer, a space in which the end portion of the second electrode layer is bent toward the first electrode layer side is less likely to occur, and the second electrode layer can be effectively prevented from coming into contact with the first electrode layer. Thereby, the photoelectric conversion element of the present invention can effectively prevent a short circuit. Further, since the photoelectric conversion element of the present invention is formed to have the shortest distance between the side surface of the first electrode layer and the side surface of the second electrode layer, conductive dust is generated across the first electrode even in the production of the photoelectric conversion element. The layer is less likely to adhere to the second electrode layer and is not easily short-circuited.

When the entire circumference of the side surface of the power generation layer is located further inward than the side surface of the first electrode layer, the shortest distance from the side surface of the first electrode layer to the side surface of the second electrode layer can be further increased, so that it is less likely to be generated. Short circuit of the photoelectric conversion element.

In addition, when the entire surface of the first electrode layer, the side surface of the power generation layer, and the side surface of the second electrode layer are covered with the insulating coating material, even if the photoelectric conversion element is externally applied, the first electrode layer and the second electrode layer can be reliably prevented. Since the electrode layers are in contact, the short circuit of the photoelectric conversion element is less likely to occur.

In addition, when an insulating tape containing polyimide is used as the insulating coating material covering the entire periphery of the side surface, the entire surface of the side surface can be covered by a simple operation of attaching, so that the photoelectric conversion element is not covered by the coating. Damage to the entire circumference of the side due to the addition of extra steps. Moreover, since the insulating tape containing the polyimide is excellent in workability, even if the side surface shape of the photoelectric conversion element is complicated, it can be accurately matched, and the dimensional accuracy is excellent. Further, since the insulating tape containing polyimine has sufficient heat resistance, it is sufficiently resistant to thermal charging when the photoelectric conversion element is loaded into the photoelectric conversion device, and does not impair the shape as an insulating coating material. .

In addition, when a thermoplastic resin composition containing at least one of an ethylene vinyl acetate copolymer resin and an urethane resin is used, as an insulating coating material covering the entire periphery of the side surface, By using a composition which is widely used as a sealing material for a photoelectric conversion device as an insulating coating material by using the same type of composition as the sealing material, the affinity between the sealing material and the insulating coating material can be improved, and the reliability of the product can be improved. It is an excellent photoelectric conversion device.

Further, when an insulating coating material covering the entire circumference of the side surface is used as a member comprising an adhesive containing polyethylene, it is used before curing. When the other photoelectric conversion elements are disposed by the above-described adhesive, the adjacent photoelectric conversion elements can be fixed while maintaining the insulating property. Such a photoelectric conversion device can be more excellent in product reliability because it is mechanically resistant to bending and the like.

In addition, when an insulating coating material including at least one selected from the group consisting of SiOx, AlOx, MgOx, and ZrOx is used, it can be improved as an insulating coating material covering the entire circumference of the side surface. The durability of the photoelectric conversion element to changes in external environment such as humidity and temperature. Therefore, a photoelectric conversion device using such a photoelectric conversion element can obtain more excellent product reliability.

Further, a photoelectric conversion device having a plurality of photoelectric conversion elements, wherein the adjacent edge portions of the photoelectric conversion elements are superposed on each other and electrically connected, each of the photoelectric conversion elements being slightly plate-shaped and having a substrate at least in sequence In the first electrode layer, the power generation layer, and the second electrode layer, the entire circumference of the side surface of the second electrode layer is formed to be located further inside than the side surface of the power generation layer, and the photoelectric conversion device can be effectively prevented from being caused by the photoelectric conversion element. The voltage of the short circuit is lowered, and the photoelectric conversion device having excellent performance can be manufactured at low cost.

1‧‧‧Substrate

2‧‧‧1st electrode layer

3‧‧‧Power generation layer

3a‧‧‧Light absorbing layer

3b‧‧‧buffer layer

4‧‧‧2nd electrode layer

5‧‧‧Insulating coverings

6‧‧‧ solder

L, L ₁ , L ₂ , L ₃ ‧‧‧ length

W‧‧‧Width

Fig. 1 is a cross-sectional view schematically showing a photoelectric conversion element according to an embodiment of the present invention.

Fig. 2 is a plan view schematically showing the state of the aforementioned photoelectric conversion element as seen from above.

3 is a schematic view showing photoelectric conversion of another embodiment of the present invention A cross-sectional view of the component.

Fig. 4 is a cross-sectional view schematically showing a photoelectric conversion element according to another embodiment of the present invention.

Fig. 5 is a perspective view partially showing a photoelectric conversion device according to an embodiment of the present invention.

Fig. 6 is a cross-sectional view partially showing the connection state of the photoelectric conversion elements of the aforementioned photoelectric conversion device.

Fig. 7(a) is a cross-sectional view schematically showing a conventional photoelectric conversion element, and Fig. 7(b) is an explanatory view showing an example in which a conventional photoelectric conversion element is short-circuited.

Form for implementing the invention

Hereinafter, the form for carrying out the invention will be described.

<Photoelectric Conversion Element>

Fig. 1 is a cross-sectional view schematically showing a photoelectric conversion element obtained by an embodiment of the present invention. The photoelectric conversion element is formed by sequentially stacking a substrate 1, a first electrode layer 2, a power generation layer 3 composed of a light absorbing layer 3a and a buffer layer 3b, and a CIGS solar cell unit of the second electrode layer 4, as shown in FIG. The entire circumference of the side surface of the second electrode layer 4 is formed at a position closer to the inner length L ₁ than the side surface of the power generation layer 3 (the light absorbing layer 3a and the buffer layer 3b). Further, when the CIGS solar battery unit emits light from the second electrode layer 4 side, a pn junction is formed at the interface between the light absorbing layer 3a and the buffer layer 3b, and an electric current can be generated. Further, when the pn junction is formed in the light absorbing layer 3a, the buffer layer 3b is not necessary. The CIGS solar battery unit will be described in detail below. In addition, in Fig. 1, each part is displayed in a mode, and the actual thickness, size, and the like are different (the same applies to the following figures). Moreover, the side of a certain layer is located at a position further on the side of a certain layer, which means that when the photoelectric conversion element is viewed from the top down (in plan view), the arrangement of the side of a certain layer is located closer to the arrangement of the side of the lower layer. The meaning of the center side of the photoelectric conversion element.

In other words, the CIGS solar cell unit uses a stainless steel foil (SUS) having a width W of 10 mm, a length L of 100 mm, and a thickness of 50 μm as the substrate 1, and a first electrode having a thickness of 500 nm made of molybdenum (Mo) is formed on the substrate 1. Layer 2. Further, the power generation layer 3 is formed on the first electrode layer 2, and the power generation layer 3 sequentially has light absorption composed of a compound semiconductor having a chalcopyrite crystal structure having Cu, In, Ga, and Se elements. The layer 3a (thickness: 2000 nm), the buffer layer 3b composed of a CdS layer (thickness: 50 nm, not shown) and a ZnO layer (thickness: 70 nm, not shown) (return to Fig. 1). Further, a second electrode layer 4 having a thickness of 200 nm made of ITO is formed on the power generation layer 3 (buffer layer 3b), and the entire circumference of the side surface is formed to be the side of the power generation layer 3 (the light absorbing layer 3a and the buffer layer 3b). It is located at the inner length L ₁ (in this case, L ₁ = 50 μm).

According to the CIGS solar cell unit of the above configuration, since the entire circumference of the side surface of the second electrode layer 4 is located at the inner side length L ₁ = 50 μm than the side surface of the power generation layer 3, even if there is a shortage at the end portion of the power generation layer 3, There is no space in which the end portion of the second electrode layer 4 can be bent toward the first electrode layer 2 side, and there is little concern that the second electrode layer 4 is in contact with the first electrode layer 2 . Thereby, the CIGS solar cell unit is not easily short-circuited. Further, in the CIGS solar battery unit, since the shortest distance from the side surface of the second electrode layer 4 to the side surface of the first electrode layer 2 becomes longer, the conductive dust crosses during or after the manufacture of the CIGS solar battery unit. The possibility of adhesion between the first electrode layer 2 and the second electrode layer 4 is extremely low, and it is not easily short-circuited. Thus, the aforementioned CIGS solar battery unit can exhibit excellent performance for a long period of time.

Further, in the above-described embodiment, the entire circumference of the side surface of the second electrode layer 4 is located 50 μm (L ₁ = 50 μm) on the inner side of the side surface of the power generation layer 3, but the side position of the second electrode layer 4 is not affected by this. limit. However, the aforementioned L ₁ is preferably 5 to 1000 μm. In other words, when L _{1 is} less than 5 μm, if 0.1 to 5 μm of dust existing in a typical clean room (ISO 14644) is electrically conductive, the dust adheres across the first electrode layer 2 and the second electrode layer 4 to cause a short circuit. Doubt. In addition, when L _{1 is} more than 1000 μm, the portion of the power generation layer 3 that is not covered by the second electrode layer 4 and is exposed is excessively large, and is invaded by moisture or other impurities, and the photoelectric conversion property tends to be lowered.

Further, in the above-described embodiment, a stainless steel foil (SUS) is used as the substrate 1. However, it may be used from a glass substrate, a metal substrate, a resin substrate or the like as needed for the purpose or design. Examples of the glass substrate include a blue plate glass, a low alkali glass (high strain point glass) having an extremely low content of an alkali metal element, and an alkali-free glass containing no alkali metal element.

Further, when the CIGS solar battery unit is manufactured by a roll-to-roll method or a stepping roll method, it is preferable that the substrate 1 has a long sheet shape and has flexibility. In addition, the "long sheet shape" means that the length in the longitudinal direction is 10 times or more the length in the width direction, and it is preferable to use 30 times or more.

Further, in the above embodiment, the thickness of the substrate 1 is 50 μm, but a substrate other than the thickness may be used. However, the thickness of the substrate 1 is preferably in the range of 30 μm or more and 200 μm or less, and more preferably in the range of 50 μm or more and 100 μm or less. That is, when the thickness is too thick, the CIGS solar power will be lost. The flexibility of the cell unit, the stress applied during bending becomes large, and there is a concern that damage to its internal structure. Conversely, if it is too thin, when the CIGS solar cell unit is manufactured, the substrate 1 is bucked and there is a CIGS solar cell unit. The tendency of product defect rate to rise.

Further, in the above embodiment, molybdenum (Mo) is used as the material for forming the first electrode layer 2, but other than W, Cr, Ti, or the like may be used. Further, the first electrode layer 2 may be a single layer or a multiple layer. Further, the thickness (the total thickness of each layer in the case of a double layer) is preferably 50 nm or more and 1000 nm or less.

Further, in the above-described embodiment, the thickness of the light absorbing layer 3a formed on the first electrode layer 2 is 2,000 nm, but may be formed to have a thickness other than the thickness. However, the thickness of the light absorbing layer 3a is preferably in the range of 1.0 μm or more and 3.0 μm or less, and more preferably in the range of 1.5 μm or more and 2.5 μm or less. When the thickness is too small, the amount of light absorption decreases, and the performance of the CIGS solar cell unit tends to decrease. On the other hand, when it is too thick, the time required for formation of the light absorbing layer 3a increases, and productivity tends to be poor.

Further, the composition ratio of Cu, In, and Ga in the light absorbing layer 3a is preferably such that 0.7<Cu/(Ga+In)<0.95 (mole ratio) is satisfied. When this formula is satisfied, Cu( _2- x)Se is excessively prevented from being absorbed in the light absorbing layer 3a, and the entire layer can be in a state in which only Cu is insufficient. Further, in the light absorbing layer 3a, the ratio of Ga to In of the same element is preferably in the range of 0.10 < Ga / (Ga + In) < 0.60 (mole ratio).

Further, in the above-described embodiment, the buffer layer 3b formed on the light absorbing layer 3a has a CdS layer (thickness: 50 nm, not shown) and a ZnO layer (thickness: 70 nm, not shown) formed on the substrate 1 side, but In addition to CdS and ZnO, a material for forming the buffer layer 3h may be ZnMgO, Zn(OH) ₂ , In ₂ O ₃ , In ₂ S ₃ , or a mixed crystal of Zn(O, S, OH). Further, when a high-resistance n-type semiconductor or the like which can be pn-bonded to the light absorbing layer 3a is used, the buffer layer 3b can also be used as a single layer. Further, the thickness of the buffer layer 3b is preferably 30 nm or more and 200 nm or less in either of the single layer and the double layer.

Further, in the above-described embodiment, ITO is used as the material for forming the second electrode layer 4 formed on the buffer layer 3b, but other materials having a high light transmittance such as ZnO, In ₂ O ₃ or SnO ₂ may be used. Further, in the above embodiment, the thickness of the second electrode layer 4 is set to 200 nm, but may be formed to have a thickness other than the thickness. However, the thickness of the second electrode layer 4 is preferably 100 nm or more and 2000 nm or less from the viewpoint of light transmittance and conductivity.

Further, the material for forming the second electrode layer 4 is preferably for the purpose of improving conductivity or for adjusting the energy band arrangement, and it is preferable that the material used for the second electrode layer 4 contains a small amount of dopant material. Examples of such a doping material include Al:ZnO (AZO), B:ZnO (BZO), Ga:ZnO (GZO), Sn:In ₂ O ₃ (ITO), F:SnO ₂ (FTO), and Zn. : In ₂ O ₃ , Ti: In ₂ Oe, Zr: In ₂ O ₃ , W: In ₂ O ₃ .

Further, although it is not used in the above embodiment, it is preferable to provide an impurity diffusion preventing layer on the substrate 1 when there is a concern that the impurities from the substrate 1 adversely affect the CIGS solar cell. As the material for forming the impurity diffusion preventing layer, Cr, SiO ₂ , Al ₂ O ₃ , TiN, TiO ₂ , Ni, NiCr, Co or the like can be used. From the viewpoint of balance of effects and cost, the thickness is preferably 50 nm or more and 1000 nm or less. Further, the impurity diffusion preventing layer may be formed on the first electrode layer 2 without being formed on the substrate 1.

Such a CIGS solar cell unit can be manufactured, for example, in the following manner. In other words, the long-sheet-shaped substrate 1 is prepared, and the first electrode layer 2 is formed on the surface thereof, and the light-absorbing layer 3a is formed thereon, and is cut into a predetermined size, and then sequentially laminated on the light-absorbing layer 3a. Buffer layer 3b and second electrode layer 4. Next, the side surface (end surface) of the second electrode layer 4 is mechanically engraved to the inner region of the predetermined position at the second electrode layer 4. Thereby, the entire circumference of the side surface of the second electrode layer 4 can be obtained as a CIGS solar battery cell located further inward than the side surface of the power generation layer 3 (the light absorbing layer 3a and the buffer layer 3b). Hereinafter, the production method will be described in detail in each formation step of each layer.

[Formation of the first electrode layer 2]

The substrate 1 made of a long sheet of SUS was prepared, and the substrate 1 was transferred by a roll-to-roll method, and the first electrode layer 2 made of Mo having a thickness of 500 nm was formed on the surface thereof by sputtering.

[Formation of Light Absorbing Layer 3a]

On the first electrode layer 2, in a state where the holding substrate 1 is 420 ° C, gallium selenide and indium selenide are sequentially deposited in a solid phase state to form a layer (α) having indium, gallium, and selenium. Further, in a state where the temperature of the substrate 1 is maintained at 420 ° C, copper selenide is laminated on the layer (α) to form a layer (β) having copper and selenium. On the substrate 1, a layer of Se vapor was supplied to the laminate in which the first electrode layer 2, the layer (α), and the layer (β) were laminated, and the temperature of the substrate 1 was set to 650 ° C, and the state was maintained for 15 minutes. Thereby, the layer (β) is in a liquid phase state, and copper in the layer (β) diffuses in the layer (α) and grows into crystals. Then, while maintaining the temperature of the substrate 1 at 650 ° C, a small amount of Se vapor was supplied, and while the vapor deposition amount of Ga was gradually increased, In, Ga, and Se were vapor-deposited to form a CIGS layer having a thickness of 2000 nm. and Further, NaF was deposited on the CIGS layer, and then the temperature of the substrate 1 was set to 420 ° C. By maintaining this state for 10 minutes, Na was diffused toward the grain boundary of the CIGS layer to form the light absorbing layer 3a.

Further, in the present invention, the solid phase means a phase which is solid at the temperature, and the liquid phase means a phase which is a liquid state at the temperature. Further, the gas phase means the phase which is a gaseous state at this temperature.

[Formation of Buffer Layer 3b]

When the first electrode layer 2 and the light absorbing layer 3a are formed by the above-described roll-to-roll method, the substrate 1 wound into a roll shape is again wound up, and is cut into a predetermined length by a cutting device to obtain a predetermined size. Laminate (substrate 1 + first electrode layer 2+ light absorbing layer 3a). Further, on the light absorbing layer 3a of the laminate, a CdS layer (thickness: 50 nm) is formed by a solution growth method (CBD method), and a ZnO layer (thickness: 70 nm) is formed on the CdS layer by sputtering. A buffer layer 3b composed of a CdS layer and a ZnO layer.

[Step of Forming Second Electrode Layer 4]

A second electrode layer 4 (thickness: 200 nm) made of ITO was formed on the buffer layer 3b by sputtering. Next, the second electrode layer 4 in the region of 50 μm from the side (end portion) is removed by using a mechanical engraver, whereby the entire circumference of the side surface of the second electrode layer 4 is formed to be located in the self-generating layer 3 (light absorption) The side of the layer 3a and the buffer layer 3b) has a length L ₁ = 50 μm toward the inner side. Further, an extraction electrode (not shown) such as a gate electrode may be formed on the second electrode layer 4 by the same method as the first electrode layer 2. In this way, a CIGS solar cell unit is available.

According to this method, a vapor deposition device (roller-to-roller) Since the CIGS solar cell unit which can effectively prevent the occurrence of a short circuit is continuously formed, it is expected that the manufacturing efficiency and cost can be reduced.

Further, in the above embodiment, the roller pair roller is formed to the light absorbing layer 3a, but it may be formed one by one by adjusting the size of the substrate 1 or the like. Further, the first electrode layer 2 is formed by sputtering, but it may be formed by a vapor deposition method, an inkjet method, a plating method, or the like.

Further, in the above embodiment, Na is added to the light absorbing layer 3a by NaF, but it may be carried out using other Na compounds such as Na ₂ Se or Na ₂ S. Further, in the above-described embodiment, Na is added to the light absorbing layer 3a by a vapor deposition NaF annealing method, but a method of depositing NaF on the first electrode layer 2 before forming the light absorbing layer 3a may be performed. .

Further, in the above embodiment, the CdS layer is formed by a solution growth method (CBD method), and the ZnO layer is formed by a sputtering method, but the layers may be formed by other methods, or may be vacuum Formed in any of medium, atmospheric, and aqueous solutions. For example, the method of performing in a vacuum may be, for example, a molecular beam epitaxy method, an electron beam evaporation method, a resistance heating vapor deposition method, a plasma CVD method, or an organic metal vapor deposition method, in addition to the sputtering method. Further, a method of performing the solution in an aqueous solution may be exemplified by a CBD method, a plating method, or the like.

Further, in the above embodiment, the region from the side surface (end portion) of the second electrode layer 4 to the inner side of 50 μm is removed by using a mechanical engraver, whereby the entire circumference of the side surface of the second electrode layer 4 is formed as the power generation layer 3 The side faces of the light absorbing layer 3a and the buffer layer 3b are located at the inner side length L ₁ = 50 μm, and other methods may be used. In such a method, for example, the second electrode layer 4 is not formed on the end portion of the power generation layer 3 to the inside of 50 μm in advance using a metal mask, photoresist etching or the like.

Further, in the above embodiment, the second electrode layer 4 is formed by a sputtering method, but may be formed by a vacuum deposition method, an organometallic vapor phase growth method, or the like.

Fig. 3 shows another embodiment of the above embodiment. Wherein, the entire circumference of the side surface of the power generation layer 3 (the light absorbing layer 3a and the buffer layer 3b) is formed to be located further inward than the side surface of the first electrode layer 2 below, and this point is the CIGS solar battery unit shown in FIG. Different. The other structure is the same as the CIGS solar cell unit shown in Fig. 1, and the description thereof will be omitted. The CIGS solar cell unit can be manufactured, for example, as follows. That is, after the second electrode layer 4 is formed, the side surface (end surface) of the second electrode layer 4 is removed by a mechanical engraver to a region inside the 100 μm, and the second electrode layer 4 (L ₁ ) in the region is removed. Then, the side surface (end surface) of the power generation layer 3 (light absorbing layer 3a, buffer layer 3b) which is removed by the mechanical engraving is removed to the inner side of 50 μm, and the power generation layer 3 (light absorbing layer 3a) in the field is removed. , buffer layer 3b) (L ₂ ). Thereby, the entire circumference of the side surface of the second electrode layer 4 is located closer to the inner side length L ₃ = 50 μm than the side surface of the power generation layer 3 (the light absorbing layer 3a and the buffer layer 3b), and the power generation layer 3 (the light absorbing layer 3a, the buffer) The entire circumference of the side surface of the layer 3b) is located at the inner side length L ₂ = 50 μm than the side surface of the first electrode layer 2.

According to the CIGS solar battery unit of the other embodiment, in addition to the effect of achieving the CIGS solar cell unit of FIG. 1, the shortest distance from the side surface of the second electrode layer 4 to the side surface of the first electrode layer 2 is further increased, so that it can be more effective. Ground suppression of short circuit generation.

In the other embodiment, the entire side surface of the second electrode layer 4 is located on the inner side of the power generation layer 3 (the light absorbing layer 3a and the buffer layer 3b) at a position of 50 μm (L ₃ = 50 μm) on the inner side, and the power generation layer. 3 (the light absorbing layer 3a and the buffer layer 3b) is located on the inner side of the first electrode layer 2 at a position 50 μm (L ₂ = 50 μm) on the inner side, but is not limited thereto.

Further embodiments are shown in Fig. 4. The entire circumference of the side surface of the power generation layer 3 (the light absorbing layer 3a and the buffer layer 3b) is formed to be located further inside than the side surface of the first electrode layer 2 below, and the substrate 1, the first electrode layer 2, the power generation layer 3, and the second layer are formed. The entire circumference of all the side faces of the electrode layer 4 is covered with the insulating coating material 5. The other structure is the same as that of the CIGS solar battery unit shown in Fig. 1 or Fig. 3, and the description thereof will be omitted. The CIGS solar cell unit can be obtained, for example, by fabricating a CIGS solar cell unit as shown in Fig. 3 and coating the side surface thereof with an insulating tape having polyimide.

According to the CIGS solar battery unit of the other embodiments described above, the effect of the CIGS solar battery unit shown in FIGS. 1 and 3 can be obtained, and the side surface of the second electrode layer 4 can be stably held to the side of the first electrode layer 2. Since the shortest distance is in a long state, the occurrence of a short circuit can be further suppressed.

It is preferable to use the above-mentioned insulating tape having a polyimide, for example, by using the polyimine tape (No. 360 UL) manufactured by Nitto Denko Corporation as an example.

Further, in the present invention, "insulating property" means electrical insulation. In addition, the "containing", "having", and "including" components also include the purpose of including only the component.

Further, in the other embodiments described above, the insulating coating material 5 is made of an insulating tape having a polyimide, but in addition to the polyimide. In addition to the edge tape, it is also possible to use other insulation which does not cause the first electrode layer 2 and the second electrode layer 4 to directly face each other to cover the side faces.

The insulating coating material 5 is insulating from the side surface of the first electrode layer 2 and the second electrode layer 4, and may include thermoplasticity of at least one of an ethylene vinyl acetate copolymer resin and an urethane resin. The resin composition is exemplified. In other words, the ethylene vinyl acetate copolymer resin is a composition common to the sealing material for sealing a photoelectric conversion device, and by using the same type of composition as the coating material and the sealing material, the affinity with the sealing material of the photoelectric conversion device can be improved. The photoelectric conversion device excellent in product reliability is obtained. In addition, when an adhesive containing a urethane resin is used as the insulating coating material 5, the other photoelectric conversion elements are disposed only through the adhesive, and the adjacent photoelectric conversion elements can be fixed while maintaining the insulating property. It is preferable to increase the mechanical punching such as bending to obtain a photoelectric conversion device excellent in product reliability. In addition, when an insulating coating material 5 is formed using a layer composed of an inorganic oxide (including at least one selected from the group consisting of SiOx, AlOx, MgOx, and ZrOx), the humidity can be improved. It is preferable that the durability of the external environment such as the temperature is excellent, and the product is excellent in reliability.

The ethylene vinyl acetate copolymer resin is exemplified by Ultraraparl PV (manufactured by Sanvic) and EVASOFT (manufactured by Bridgestone).

The above-mentioned urethane-containing resin-containing adhesive is preferably an urethane-based thiol-based adhesive from the viewpoint of water resistance, and may be exemplified by #05140 manufactured by Konishi Co., Ltd.

Further, the layer composed of an inorganic oxide (including at least one selected from the group consisting of SiOx, AlOx, MgOx, and ZrOx) can be steamed. A wet process such as a plating method, a sputtering method, a plasma CVD method, or the like, a sol-gel method or the like is formed. Further, the inorganic acid compounds may be a single layer made of a single material, or may be a plurality of layers of different types of laminates. Further, it may be a layer in which a plurality of materials are combined, or a plurality of layers in which the layers are laminated.

Further, in the other embodiment, the insulating coating material 5 is disposed so as to cover the side surfaces of all the layers of the substrate 1 to the second electrode layer 4, but is not limited thereto. However, when the side faces of all the layers are covered as described above, it is preferable to prevent moisture or the like from intruding into the end faces of all the layers of the substrate 1 to the second electrode layer 4, and to further improve the insulating property.

<Photoelectric conversion device>

Next, an outline of the photoelectric conversion device of the present invention is shown in Fig. 5 . A CIGS solar cell module having a plurality of CIGS solar cell units obtained in the above embodiments and having their adjacent edge portions superposed on each other and electrically connected. The CIGS solar cell module is electrically connected in series to a plurality of CIGS solar cell units, and a practical voltage can be obtained.

The electrical connection of the CIGS solar cell unit can be realized by the following example. As shown in FIG. 6, the edge of the first electrode layer 2 of the CIGS solar cell unit on one side of the solder 6 is overlapped, and the CIGS solar cell unit on the other side. The edge of the second electrode layer 4. Further, a conductive film may be sandwiched between the CIGS solar cell unit and the solder 6. Generally, a CIGS solar battery module in which a CIGS solar battery unit group is electrically connected is integrally sealed with a weather-resistant sealing film or the like.

In the CIGS solar cell module thus obtained, since the CIGS solar cell units are not short-circuited, there is no voltage drop and can be maintained for a long time. Excellent performance.

Next, the examples and comparative examples will be described together. However, the invention is not limited thereto.

Example

[Example 1]

First, a substrate 1 of a stainless steel foil SUS430 (10 x 100 mm in size and 50 μm in thickness) was prepared, and a first electrode layer 2 made of Mo and having a thickness of 500 nm was laminated thereon. Then, the substrate 1 on which the first electrode layer 2 was formed was placed in a vacuum vapor deposition apparatus, and gallium selenide (thickness: 400 nm) was sequentially deposited on the first electrode layer 2 while maintaining the substrate temperature of 420 ° C. Indium selenide (thickness 1000 nm) forms a layer (α) having selenium, gallium and indium. Next, copper selenide (thickness: 600 nm) was laminated on the layer (α) while maintaining the substrate temperature of 420 ° C to form a layer (β) having copper and selenium. A small amount of Se vapor was supplied, and a laminate in which the layers (α) and (β) were laminated was heated, and the substrate temperature was maintained at 650 ° C for 15 minutes to grow crystals. Then, a small amount of Se vapor was supplied and the substrate temperature was maintained. In a state of 650 ° C, while gradually increasing the vapor deposition amount of Ga, In, Ga, and Se were vapor-deposited to form a CIGS layer (thickness: 2000 nm).

Next, the laminated body in which the CIGS layer was formed was cooled, the substrate temperature was maintained at 400 ° C, and NaF was vacuum-deposited on the CIGS layer using a NaF vapor deposition source set at 750 ° C, and then the substrate temperature was 420 ° C by heating. The light absorbing layer 3a was formed by diffusing Na at the grain boundary of the CIGS layer by maintaining the substrate temperature for 10 minutes.

Further, on the light absorbing layer 3a, a buffer layer 3b having a CdS layer (thickness: 50 nm) and a ZnO layer (thickness: 70 nm) is laminated in this order, and is composed of ITO. The second electrode layer 4 (thickness: 200 nm). Thereafter, the side surface (end surface) of the second electrode layer 4 is removed by mechanical engraving to a region inside the 50 μm, and the second electrode layer 4 in the region is removed, and the entire circumference of the side surface of the second electrode layer 4 is formed as the power generation layer 3 ( The side faces of the light absorbing layer 3a and the buffer layer 3b) were located at an inner side of 50 μm to manufacture a CIGS solar battery unit.

[Embodiment 2]

A CIGS solar battery cell was produced in the same manner as in Example 1 except that the entire circumference of the side surface of the second electrode layer 4 was formed at a position of 500 μm on the inner side of the side surface of the power generation layer 3 (the light absorbing layer 3a and the buffer layer 3b).

[Example 3]

Further, in addition to irradiating Nd:YAG laser light to the side surface (end surface) of the power generation layer 3 (light absorbing layer 3a, buffer layer 3b) to the inner side of 20 μm, the power generation layer 3 (light absorbing layer 3a, buffer layer) in the region is removed. A CIGS solar battery unit was produced in the same manner as in Example 1 except for 3b). In other words, the entire circumference of the side surface of the second electrode layer 4 is located at a position 30 μm inside from the side surface of the power generation layer 3 (the light absorbing layer 3a and the buffer layer 3b), and the side of the power generation layer 3 (the light absorbing layer 3a and the buffer layer 3b) The entire periphery is located 20 μm (see FIG. 3) on the inner side of the side surface of the first electrode layer 2.

[Examples 4 to 10]

A CIGS solar cell was produced in the same manner as in Example 3 except that the entire surface of the insulating coating material covering substrate 1, the first electrode layer 2, the power generating layer 3, and the second electrode layer 4 shown in Table 1 below was prepared. unit.

[Comparative Example 1]

Except that the side surface (end surface) of the second electrode layer 4 is not removed to the inner area of 50 μm A CIGS solar battery cell was produced in the same manner as in Example 1 except that the second electrode layer 4 was used. That is, in the CIGS solar battery cell of Comparative Example 1, the side faces of the second electrode layer 4 and the side faces of the power generation layer 3 (the light absorbing layer 3a and the buffer layer 3b) are formed at the same position in plan view.

[Comparative Example 2]

Except for removing only the two sides of the adjacent CIGS solar cell unit, the side surface (end surface) of the second electrode layer 4, and the second electrode layer 4 in the inner region of 50 μm, and the remaining two sides are not subjected to the second electrode layer. A CIGS solar cell unit was produced in the same manner as in Example 1 except that the removal of 4 was carried out. That is, the entire circumference of the side surface of the second electrode layer 4 in the CIGS solar cell unit is not located inside the side position of the power generation layer 3.

The reverse saturation currents in the darkness of the CIGS solar cell units of the above Examples 1 to 10 and Comparative Examples 1 and 2 were measured in the following order. Further, the CIGS solar battery cells of the above-described Examples 1 to 10 and Comparative Examples 1 and 2 were electrically connected by a pair of solders to produce respective CIGS solar battery modules. In addition, the entire CIGS solar cell module was covered with a cover film (VIEW-BARRIER, manufactured by Mitsubishi Plastics Chemical Co., Ltd.) having flexibility and weather resistance. The reliability test (DH) of the CIGS solar cell module was performed in the following order. The results of these are shown together in Table 1 below.

[Reverse saturation current in the dark]

The measurement of the reverse saturation current in the dark can be performed as follows. That is, the CIGS solar cell unit is mounted on a measuring platform whose temperature is adjusted to 25 ° C in a dark ambient gas, and the current is measured while sweeping the voltage, and the current value when a negative bias of -5 V is applied is recorded as the CIGS sun. Battery unit in the dark Reverse saturation current value.

[Reliability Test (DH)]

The reliability test was performed by using ESPEC's high temperature and humidity tester (PL-3J) to expose the CIGS solar cell module to an ambient gas maintained at 85 ° C and a humidity of 85% for 1000 hours. Further, the ratio of the photoelectric conversion efficiency after 1000 hours to the conversion efficiency before the start of the test was 90% or more, and it was judged as the pass (○ mark), and the case where the ratio was less than 90% was evaluated as the unacceptable (X mark).

Moreover, the insulating coating material shown in Table 1 uses the following.

*1: Polyimide tape (made by Nitto Denko Corporation, No.360UL)

*2: ethylene vinyl acetate copolymer resin composition (manufactured by Sanvic) Ultrapearl PV)

*3: Ethyl urethane-sulfonium-based adhesive (Konishi Co., Ltd., #05140)

From the above results, it was found that the reliability test (DH) of the CIGS solar cell module was acceptable to all of Examples 1 to 10, and both of Comparative Examples 1 and 2 failed. Further, in the examples, the CIGS solar battery cells of Examples 5 to 10 covering the entire side surfaces of the substrate 1, the first electrode layer 2, the power generation layer 3, and the second electrode layer 4 were covered with an insulating coating material, particularly in the dark. The reverse saturation current value is low, and an excellent short-circuit prevention effect can be obtained.

Further, in the present invention, a CIGS solar battery unit will be described as an example of a photoelectric conversion element, but the same effect can be obtained by using another type of solar battery unit.

In the foregoing embodiments, the specific embodiments of the present invention are shown, but the foregoing embodiments are merely illustrative and not restrictive. Various modifications known to those skilled in the art are within the scope of the invention.

Industrial availability

Since the photoelectric conversion element of the present invention can effectively prevent short-circuiting, high conversion efficiency can be achieved at low cost. Further, the photoelectric conversion device having the photoelectric conversion element is suitable for a photoelectric conversion device which requires a high specification for a long period of time.

1‧‧‧Substrate

2‧‧‧1st electrode layer

3‧‧‧Power generation layer

3a‧‧‧Light absorbing layer

3b‧‧‧buffer layer

4‧‧‧2nd electrode layer

L ₁ ‧‧‧ length

Claims (8)

A photoelectric conversion element characterized in that it has a substantially plate shape and has at least a substrate, a first electrode layer, a power generation layer, and a second electrode layer, and the entire circumference of the side surface of the second electrode layer is formed. The side surface of the power generation layer is located at the inner side. The photoelectric conversion element according to claim 1, which has a substantially plate shape and has at least a substrate, a first electrode layer, a power generation layer, and a second electrode layer, and the entire circumference of the side surface of the power generation layer is formed to be located closer to the first electrode layer. The side of the side is more inside. The photoelectric conversion element according to claim 1 or 2, which has a substantially plate shape and has at least a substrate, a first electrode layer, a power generation layer, and a second electrode layer, and a side surface of the first electrode layer, a side surface of the power generation layer, and a surface The entire circumference of the side surface of the two electrode layers is covered with an insulating coating material. The photoelectric conversion element according to claim 3, wherein the insulating coating material covering the entire circumference of the side surface comprises an insulating tape of polyimine. The photoelectric conversion element according to claim 3, wherein the insulating coating material covering the entire circumference of the side surface is composed of a thermoplastic resin composition containing at least one of an ethylene vinyl acetate copolymer resin and an urethane resin. The photoelectric conversion element according to claim 3, wherein the insulating coating material covering the entire circumference of the side surface is made of an adhesive containing polyethylene. The photoelectric conversion element according to claim 3, wherein the insulating coating material covering the entire circumference of the side surface is formed by an inorganic oxide, The organic oxide includes at least one selected from the group consisting of SiOx, AlOx, MgOx, and ZrOx. A photoelectric conversion device having a plurality of photoelectric conversion elements, wherein the adjacent edges of the photoelectric conversion elements are superposed on each other and electrically connected, the photoelectric conversion device being characterized in that each of the photoelectric conversion elements is as claimed in claim 1 The photoelectric conversion element according to any one of the above-mentioned seventh aspect, which has a substantially plate shape and has at least a substrate, a first electrode layer, a power generation layer, and a second electrode layer, and the entire circumference of the side surface of the second electrode layer is formed to generate electricity The side of the layer is located on the inner side.