JP2014015662A - Method for producing compound semiconductor solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method that enables producing a compound semiconductor solar cell of high conversion efficiency at low cost.SOLUTION: A compound semiconductor layer is formed on a long substrate 1 by vacuum deposition method while travelling the substrate 1 by using a vapor deposition source A having a nozzle 12 for supplying Se and a vapor deposition source B having a supply port 14 for supplying Cu, In and Ga, in which the supply port 14 is disposed away from the substrate 1 by 5 to 70 mm and a tip opening 13 of the nozzle 12 of the vapor deposition source A, the supply port 14 of the vapor deposition source B and the substrate 1 are arranged at specific positions so that the Se is injected from the tip opening 13 of the nozzle 12.

Description

The present invention has high light conversion efficiency (hereinafter referred to as “conversion efficiency”), CuInSe ₂ (CIS) composed of Group I, Group III and Group VI elements, or Cu (In) in which Ga is dissolved. , Ga) Se ₂ (CIGS) compound semiconductor (I-III-VI group compound semiconductor) The present invention relates to a method for efficiently producing a compound solar cell using a light absorption layer.

  Among solar cells, a compound solar cell using a CIS or CIGS (hereinafter referred to as “CIGS-based”) compound semiconductor for a light absorption layer has a high conversion efficiency and can be formed into a thin film, and has a conversion efficiency due to light irradiation or the like. It is known to have the advantage of less degradation.

  The present applicant has already proposed the invention described in Patent Document 1 below as a method for efficiently producing a compound solar cell using such a CIGS compound semiconductor as a light absorption layer. The invention described in Patent Document 1 is characterized in that when a light absorbing layer is continuously formed by a vapor deposition method using a long substrate, the distance between the substrate and the vapor deposition source is made close. As a result, the light absorbing layer can be formed at high speed and stably as compared with the conventional vapor deposition method.

JP 2011-176148 A

  However, although the invention described in Patent Document 1 exhibits the above-described excellent effects, the base material and the vapor deposition source are close to each other, so that the group VI material is replaced with other materials (group I and group III materials). It was found that the composition ratio of group VI in the obtained light absorption layer tends to be low. In order to prevent this, it is necessary to supply an excessive amount of Group VI material, which is uneconomical. Therefore, further improvement is required.

  The present invention has been made in view of the above-described problems. When the light absorption layer is formed by a vapor deposition method in which a base material and a vapor deposition source are brought close to each other, light can be emitted without excessively supplying a group VI material. It is an object of the present invention to provide a method for stably producing a compound solar cell having a high conversion efficiency, in which the composition ratio of the VI group in the absorption layer can be sufficiently increased.

In order to achieve the above object, the present invention provides a method for producing a compound solar cell in which a compound semiconductor layer is formed on a substrate by vapor deposition while running a long substrate, and the compound semiconductor The layer is formed by using a vapor deposition source A provided with a nozzle for supplying a group VI element material and a vapor deposition source B having a supply port for supplying other element materials, The B supply port is disposed at a position 5 to 70 mm away from the base material, and the front end opening of the nozzle of the vapor deposition source A, the supply port of the vapor deposition source B, and the base material are represented by the following general formulas (1) to (4). The gist of the method is a compound solar cell manufacturing method in which the group VI element material is supplied in a sprayed state while being heated from the opening of the tip of the nozzle of the evaporation source A.
L ₁ / sin θ ₁ ≦ L ₂ / sin θ ₂ (1)
0 ° ≦ θ ₁ ≦ 30 ° (2)
θ ₁ ≦ θ ₂ ≦ 90 ° (3)
L ₁ <L ₂ (4)
θ ₁ : Angle (°) formed by a virtual line I ₁ indicating the ejection direction of the group VI element material from the tip opening of the nozzle of the evaporation source A and the base material
θ ₂ : Angle (°) formed by a virtual line I ₂ indicating the supply direction of elemental material other than the group VI from the supply port of the evaporation source B and the base material
L ₁ : Shortest distance (mm) between the nozzle tip opening of the evaporation source A and the substrate surface
L ₂ : The shortest distance (mm) between the supply port of the evaporation source B and the substrate surface

  “Forming a compound semiconductor layer on a base material” by vapor deposition means forming a compound semiconductor layer above the base material, and forming the compound semiconductor layer on the base material via another layer. It means to include. That is, it does not mean that the compound semiconductor layer is formed directly on the substrate.

  The method for producing a compound solar cell according to the present invention comprises forming a compound semiconductor layer by vapor deposition provided with a vapor deposition source A provided with a nozzle for supplying a group VI element material and a supply port for supplying other elemental material. The source B is used, and the supply port of the vapor deposition source B is disposed at a position 5 to 70 mm away from the base material, and the tip opening of the nozzle of the vapor deposition source A, the supply port of the vapor deposition source B, and the base material Are arranged at positions satisfying the above general formulas (1) to (4). According to this method, since the substrate and each deposition source are extremely close to each other, the compound semiconductor layer can be formed at high speed and stably. In addition, since the group VI element material is supplied in a sprayed state from a position closer to the base material than the supply port of the element material other than group VI by passing through the nozzle, the group VI element material is supplied to other elements. It can be sufficiently reacted with elemental materials (Group I and Group III materials), and the group VI composition ratio in the compound semiconductor layer can be increased efficiently. In addition, since the tip opening of the nozzle of the vapor deposition source A, the supply port of the vapor deposition source B, and the base material are arranged at positions satisfying the general formulas (1) to (4), an element material of group VI is used. It is possible to wrap around other elemental materials (Group I and Group III element materials) and to react sufficiently with each other. Therefore, according to the production method of the present invention, it is not necessary to supply the group VI element material excessively as in the conventional case, and an excellent compound solar cell with high conversion efficiency can be efficiently produced at low cost.

  If the compound semiconductor layer has a chalcopyrite structure composed of Group I, Group III, and Group VI elements, it is possible to perform high-efficiency light conversion even with a thin film and to be stable at room temperature. .

  Further, the nozzle attached to the vapor deposition source A is formed into a plurality of branched nozzles, and the group VI element material is supplied in a sprayed state from multiple directions by the plurality of branched nozzles. The above group VI element materials can be more efficiently circulated around the other (group I and group III) element materials and allowed to sufficiently react with each other, reducing the loss of group VI element materials. can do.

  Further, the compound semiconductor layer is formed in a vacuum chamber, and a nozzle for injecting the group VI element material is disposed in the vacuum chamber, and valve means detachable from the nozzle When the deposition source A connected by the above is disposed outside the vacuum chamber and the group VI element material is supplied from the deposition source A to the nozzle in the vacuum chamber, the VI from the deposition source A Since the supply amount of the group element material is easy, the loss of the group VI element material can be reduced and the controllability of the compound semiconductor layer composition can be further improved.

It is sectional drawing of the CIGS solar cell obtained by one embodiment of this invention. It is the schematic of the vapor deposition apparatus used for the compound semiconductor layer formation of the said CIGS solar cell. It is explanatory drawing which shows the positional relationship of the nozzle and the vapor deposition source B in the said vapor deposition apparatus. It is explanatory drawing which shows the other positional relationship of the nozzle and the vapor deposition source B in the said vapor deposition apparatus. It is explanatory drawing which shows the modification of the nozzle in the said vapor deposition apparatus. It is explanatory drawing which shows another modification of the nozzle in the said vapor deposition apparatus.

  Next, an embodiment for carrying out the present invention will be described.

  FIG. 1 is a cross-sectional view of a CIGS solar cell obtained according to an embodiment of the present invention. This CIGS solar cell has a size of width 20 mm × length 20 mm × thickness 53 μm, a base material 1 (thickness 50 μm) made of stainless alloy (SUS), and a back electrode layer 2 (thickness 800 nm) made of molybdenum (Mo). And a compound semiconductor layer (CIGS light absorption layer) 3 (thickness 2 μm) made of a chalcopyrite compound, a buffer layer 4 (thickness 70 nm) made of ZnO, and a surface electrode layer 5 (thickness 200 nm) made of ITO in this order. The compound semiconductor layer 3 is formed by a special vapor deposition method. Below, this CIGS solar cell is demonstrated in detail. In FIG. 1, the thickness, size, appearance, and the like of each layer are schematically shown, and are different from actual ones (the same applies to the following drawings).

  The base material 1 is used as a support substrate, and besides the SUS, soda lime glass, flexible metal foil, and the like can be used. However, it is preferable to use a material that can withstand heating in a subsequent heating step (for example, high temperature exceeding 520 ° C.).

  As the back electrode layer 2 formed on the substrate 1, tungsten (W), chromium (Cr), titanium (Ti), etc. can be used in addition to the Mo. It can also be used by forming in multiple layers. And it is preferable that the thickness exists in the range of 100-1000 nm.

  The CIGS light absorption layer (compound semiconductor layer) 3 formed on the back electrode layer 2 is composed of four elements of copper (Cu), indium (In), gallium (Ga), and selenium (Se). It consists of a compound semiconductor having a pyrite structure, and the composition ratio of Cu, In and Ga is 22.1: 21.2: 7.5, and Cu / (In + Ga) ≈0.77. The CIGS light absorption layer 3 is formed by a special multi-source vapor deposition method to be described later.

  Next, the buffer layer 4 formed on the CIGS light absorption layer is preferably a high-resistance n-type semiconductor so that a pn junction can be formed with the CIGS light absorption layer 3. It may consist of layers. When the buffer layer 4 is composed of a plurality of layers, the pn junction with the CIGS light absorption layer 3 can be improved. As the buffer layer 4, any material other than the above ZnO can be used. For example, CdS, ZnMgO, Zn (O, S), or the like can be used. Moreover, when using what consists of a some layer as the buffer layer 4, it is preferable that the thickness of each layer exists in the range of 30-200 nm, respectively. Even when the buffer layer 4 is a single layer, the thickness is preferably 30 to 200 nm.

  The surface electrode layer 5 formed on the buffer layer 4 is preferably formed using a material having a high transmittance. In addition to the ITO, indium zinc oxide (IZO), zinc aluminum oxide (Al: ZnO) ) Or the like. Moreover, it is preferable that the thickness exists in the range of 100-300 nm.

  In such a CIGS solar cell, for example, a back electrode layer 2 is formed on the surface of a long substrate 1, and CIGS light absorption is performed on the back electrode layer 2 using a vapor deposition apparatus 6 shown in FIG. After the layer 3 is formed and the substrate 1 is cut so as to have a predetermined size, the buffer layer 4 and the surface electrode layer 5 are laminated on the CIGS light absorption layer 3 in this order. be able to. The manufacturing method will be described in detail below.

(Back electrode process)
The back electrode layer 2 made of Mo is formed on the surface of the long base material 1 by a sputtering method while running the long base material 1 by the roll-to-roll method. The back electrode layer 2 can also be formed by a vapor deposition method in addition to the sputtering method.

(CIGS light absorption layer forming step)
Next, the CIGS light absorption layer 3 is formed on the back electrode layer 2 while the base material 1 (hereinafter referred to as “base material”) on which the back electrode layer 2 is formed is also run in a roll-to-roll manner. Form. In this step, for example, a vapor deposition apparatus 6 as shown in FIG. 2 is used. This vapor deposition apparatus 6 forms the CIGS light absorption layer 3 with respect to the base material 1 by the vapor deposition chamber 8 for unwinding the base material 1 from the unwinding roll 7 by which the base material 1 was wound, and vapor deposition. Vapor deposition chamber 9 and a winding chamber 11 for accommodating a winding roll 10 for winding the substrate 1 on which the CIGS light absorption layer 3 is formed. The chambers 8, 9, and 11 are connected by a differential exhaust mechanism for reducing the pressure difference, so that the substrate 1 can be continuously moved between chambers having different pressures. ing. The CIGS light absorption layer 3 can be continuously formed on the long base 1 by passing the base 1 through the chambers 8, 9, and 11.

  The vapor deposition chamber 9 is provided with three vapor deposition sources A provided with nozzles 12 for supplying Se (group VI element), and supplies Cu, In and Ga (elements other than group VI elements). The vapor deposition source B provided with the supply port to be provided is provided for each element (three in total). And the supply port 14 of each vapor deposition source B is arrange | positioned in the position 5-70 mm away from the base material 1, and the front-end | tip opening 13 of the said nozzle 12 is made into the base material 1 from the supply port 14 of the said vapor deposition source B. It is arranged at a close position.

The positional relationship between the tip opening 13 of the nozzle 12 attached to the deposition source A, the supply port 14 of the deposition source B, and the substrate 1 will be described in more detail. As shown in FIG. In the supply port 14, the angle θ ₂ formed by the imaginary line I ₂ indicating the supply direction of Cu, In, and Ga and the substrate 1 is 60 °, and the shortest distance L ₂ from the surface of the substrate 1 is 50 mm. It is arranged at the position. The tip opening 13 of the nozzle 12 has an angle θ ₁ formed by a virtual line I ₁ indicating the ejection direction of Se and the base material of 20 °, and a shortest distance L ₁ from the surface of the base material ₁ of 10 mm. It is arranged at the position. That is, these relationships satisfy the following general formulas (1) to (4).
L ₁ / sin θ ₁ ≦ L ₂ / sin θ ₂ (1)
0 ° ≦ θ ₁ ≦ 30 ° (2)
θ ₁ ≦ θ ₂ ≦ 90 ° (3)
L ₁ <L ₂ (4)
θ ₁ : Angle (°) formed by a virtual line I ₁ indicating the ejection direction of the group VI element material from the tip opening of the nozzle of the evaporation source A and the base material
θ ₂ : Angle (°) formed by a virtual line I ₂ indicating the supply direction of elemental material other than the group VI from the supply port of the evaporation source B and the base material
L ₁ : Shortest distance (mm) between the nozzle tip opening of the evaporation source A and the substrate surface
L ₂ : The shortest distance (mm) between the supply port of the evaporation source B and the substrate surface

  And although the opening diameter of the nozzle 12 attached to the said vapor deposition source A is 10 mm, it is preferable that it is in the range of 1-30 mm, and the opening diameter of the nozzle 12 is in the range of 5-20 mm. More preferably. That is, if the diameter is too large, the distribution of the ejected material will be good, but the ejection pressure of Se will be low, and Se may not be able to sufficiently wrap around Cu, In and Ga. If it is too small, the ejection pressure of Se is improved, but a good distribution cannot be obtained, and compositional unevenness of the Se material in the CIGS light absorption layer 3 may occur. Around the nozzle 12, heating means (for example, heating wire) is arranged (not shown) so that the Se temperature supplied from the vapor deposition source A can be adjusted. If the adjustment can be made, this heating means may not be provided. Moreover, it is preferable to install a heating means in the said vapor deposition source B in the state independent for each vapor deposition source B so that suitable heating for every material of Cu, In, and Ga can be performed.

In this example, as shown in FIG. 3, the ejection direction of Se from the tip opening 13 of the nozzle 12 (virtual line I ₁ ) and the supply direction of Cu, In, Ga from the supply port 14 of the vapor deposition source B (virtual line) Both of them are arranged so that the line I ₂ ) intersects on the surface of the base material 1 (position where the distance from the surface of the base material 1 is 0 mm). However, as shown in FIG. 4, it may be arranged such that the intersection point P between the two is located away from the surface of the base material 1. In particular, the intersection point P is 0 downward from the surface of the base material 1. It is preferable to arrange it at a position away by -5 mm. In the arrangement where the intersection point P is too far away from the surface of the base material 1, the wraparound of Se to Cu, In, and Ga does not occur in the vicinity of the substrate 1, and the composition ratio of Se in the CIGS light absorption layer 3 obtained is It tends to get worse.

In order to obtain the CIGS light absorption layer 3 using this vapor deposition apparatus 6, first, it is heated by a heating mechanism (not shown) provided in the vapor deposition chamber 9 so that the temperature of the base material 1 at the time of vapor deposition is 550 ° C. To do. At this time, the temperature of the substrate 1 may become too high due to the heat generated from the vapor deposition sources A and B, and a separate cooling mechanism (not shown) for cooling the substrate 1 is provided in the vapor deposition chamber 9. You may make it provide in. Then, the vapor deposition chamber 9 is evacuated, the vapor deposition source A (Se material unit) is heated to 350 ° C., the nozzle 12 is heated to 450 ° C., and an angle of 20 ° with respect to the substrate 1 from the tip opening 13. While injecting Se, each material unit of Cu, In, and Ga arranged as the vapor deposition source B is heated to 1300 ° C., 1100 ° C., and 1100 ° C., respectively, and 60 ° toward the substrate 1 from the supply port 14. By supplying Cu, In, and Ga at an angle, Se can sufficiently wrap around Cu, In, and Ga even when the substrate 1 and the evaporation sources A and B are close to each other. The CIGS light absorption layer 3 having a chalcopyrite structure [Cu (In _1−X , Ga _x ) Se ₂ ] having a desired composition ratio can be obtained on the substrate 1.

The nozzle 12 of the vapor deposition source A is disposed so that an angle θ ₁ formed by the imaginary line I ₁ indicating the ejection direction of Se from the tip opening 13 and the substrate ₁ is 20 °. However, the arrangement is not limited to this, but it is preferable that the angle θ ₁ is arranged to be an arbitrary angle in the range of 0 to 30 °. Further, the supply port 14 of the vapor deposition source B is arranged so that an angle θ ₂ formed by a virtual line I ₂ indicating the supply direction of Cu, In, and Ga and the substrate 1 is 60 °. However, it is preferable to dispose it so as to be an arbitrary angle in a range larger than the angle θ _{1 and not} more than 90 °.

The tip opening 13 of the nozzle 12 has a shortest distance L ₁ from the surface of the substrate 1 set to 10 mm. However, the present invention is not limited to this, and the shortest distance L ₁ is from the surface of the substrate 1 to the evaporation source B. Can be set to any range shorter than the shortest distance L ₂ to the supply port 14. Then, although the shortest distance L ₂ is set to 50 mm, not limited to this, it can be set to any scope of 5～70Mm.

  In addition, three each of the vapor deposition source A provided with the nozzle 12 for supplying Se and the vapor deposition source B provided with the supply port 14 for supplying Cu, In, and Ga are provided in the vapor deposition chamber 9. However, the number can be increased or decreased in consideration of the size of the vapor deposition chamber 9 and the base material 1, the transport speed of the base material 1, and the like. Moreover, although the vapor deposition source A and the vapor deposition source B are installed in the ratio of 1: 1, it is not necessarily required. That is, as shown in FIG. 5, when the nozzle 12 attached to the vapor deposition source A is branched in the middle of the direction of the substrate 1 and a plurality of tip openings 13 are formed, the number of the vapor deposition sources B is used. In contrast, the number of vapor deposition sources A can be reduced. In this case, since the supply of Se from the vapor deposition source A can be controlled at one place, management becomes easy. Further, even when the vapor deposition source A and the vapor deposition source B are installed at 1: 1, as shown in FIG. 6, the nozzle 12 attached to the vapor deposition source A is 2 in the middle of extending in the direction of the substrate 1. It is also possible to use one that branches in the direction and inject Se from each branched tip opening 13. In this case, it is possible to further surround Se around other elemental materials (Cu, In, Ga) supplied from the evaporation source B, and to form the CIGS light absorption layer 3 with high conversion efficiency more efficiently. can do.

  In the vapor deposition apparatus 6, both the vapor deposition source A and the nozzle 12 attached thereto are disposed in the vapor deposition chamber 9. However, the nozzle 12 is disposed in the vapor deposition chamber 9, and the nozzle 12 May be connected to a vapor deposition source A disposed outside the vapor deposition chamber 9. When the vapor deposition source A is disposed outside the vapor deposition chamber 9, it is easy to adjust the Se supply from the vapor deposition source A, so that Se loss can be reduced and the composition ratio of the CIGS light absorption layer can be more easily controlled. . And it is preferable to connect the nozzle 12 and the vapor deposition source A by a detachable valve means because the vapor deposition source A can be easily exchanged.

  And after CIGS light absorption layer 3 is formed, base material 1 is wound up with winding roll 10 as it is, but in order to raise crystallinity of CIGS light absorption layer 3, CIGS light absorption layer at predetermined temperature After heating and burning 3, the substrate 1 may be wound up by a winding roll 10. The CIGS light absorption layer 3 is heated and burned by temporarily winding the base material 1 on which the CIGS light absorption layer 3 is formed with a take-up roll 10 and then unwinding the wound base material 1. May be.

  Furthermore, the CIGS light absorption layer 3 can be formed not only by the vapor deposition method but also by a vapor deposition method such as a three-stage method or a bilayer method.

(Buffer layer forming step, surface electrode layer forming step, electrode forming step)
Next, the base material 1 on which the CIGS light absorption layer 3 is formed is unwound from the take-up roll 10 and is cut into a predetermined size by a cutting device for each predetermined length. And the buffer layer 4 is formed on the CIGS light absorption layer 3 of the base material 1 which became this predetermined size by sputtering method. The buffer layer 4 can be formed by a chemical bath deposition method (CBD method) or the like in addition to the sputtering method. Then, a surface electrode layer 5 is formed on the buffer layer 4 by a sputtering method, and a comb-shaped electrode is formed on the back surface of the substrate 1 (the surface opposite to the surface on which the CIGS light absorption layer 3 and the like are formed). Thus, a CIGS solar cell can be obtained.

  According to the manufacturing method of the CIGS solar cell, since the base material 1 and the vapor deposition sources A and B are extremely close to each other, the CIGS light absorption layer 3 can be formed at high speed and stably. In addition, since Se is supplied in an injection state from a position closer to the substrate 1 than the supply port 14 for Cu, In, and Ga by passing through the nozzle 12, Se is sufficiently reacted with Cu, In, and Ga. The composition ratio of Se in the CIGS light absorption layer 3 can be increased efficiently. In particular, since the tip opening 13 of the nozzle 12 of the vapor deposition source A, the supply port 14 of the vapor deposition source B, and the base material 1 satisfy the above-described general formulas (1) to (4), Se in particular. Can wrap around Cu, In, and Ga, and can sufficiently react with each other. Furthermore, since the CIGS light absorption layer 3 has a chalcopyrite structure, it is possible to perform high-efficiency light conversion even with a thin film and to be stable at room temperature. Therefore, according to the production method of the present invention, it is not necessary to supply Se excessively as in the prior art, and an excellent CIGS solar cell with high conversion efficiency can be efficiently produced at low cost.

  In the above-described embodiment, the CIGS light absorption layer forming step is performed by a roll-to-roll method using the long base material 1, and the steps after the buffer layer 4 are cut into a predetermined size. Although the single wafer method using the material 1 is performed, the steps after the buffer layer 4 may be performed by the roll-to-roll method similarly to the CIGS light absorption layer 3 forming step. In this case, after the surface electrode layer 5 is formed, the substrate 1 is cut into a predetermined size. Further, the substrate 1 may be used without being cut.

  Moreover, in said embodiment, although the back surface electrode layer 2 is formed on the elongate base material 1, the base material 1 has electroconductivity and can serve as the back surface electrode layer 2 as well. In that case, the back electrode layer 2 may not be provided.

  Next, examples will be described together with comparative examples. However, the present invention is not limited to the following examples.

[Example 1]
(Formation of back electrode layer)
On the surface of a base material 1 (width 30 nm, length 100 m, thickness 50 μm) made of ferrite SUS430, a roll-to-roll method is used, and Cr and Mo are laminated in this order by a DC magnetron sputtering method. Cr: thickness 100 nm, Mo: thickness 300 nm).

(Formation of CIGS light absorption layer)
Next, the substrate 1 on which the back electrode layer 2 is formed is passed over the unwinding roll 7 and the winding roll 10 of the vapor deposition apparatus 6 (see FIG. 2) used in the above embodiment, and the back electrode layer 2 The CIGS light absorption layer 3 was formed on the substrate. That is, as the nozzle 12 of the vapor deposition source A, a nozzle having an opening diameter of 10 mm at the tip opening 13 was prepared, and as the vapor deposition source B, an nozzle having an opening diameter of 27.5 mm was prepared. And in the vapor deposition chamber 9 of the vapor deposition apparatus 6, the front-end | tip opening 13 of the nozzle 12 of the vapor deposition source A, the supply port 14 of the vapor deposition source B, and the base material 1 were arrange | positioned so that it might become the relationship shown below.
The angle θ ₁ formed by the virtual line I ₁ indicating the ejection direction of Se from the tip opening 13 of the nozzle 12 of the vapor deposition source A and the substrate ₁ is 20 °.
The angle θ ₂ formed by the virtual line I ₂ indicating the supply direction of Cu, In, and Ga from the supply port 14 of the vapor deposition source B and the substrate 1 is 90 °.
The shortest distance L ₁ between the tip opening 13 of the nozzle 12 of the vapor deposition source A and the surface of the substrate ₁ is 15 mm.
The shortest distance L ₂ between the supply port 14 of the vapor deposition source B and the surface of the substrate 1 is 50 mm.
A position where the intersection point P between the virtual line I ₁ and the virtual line I ₂ is 2 mm away from the surface of the substrate 1.

And the surface temperature of the base material 1 is 250 by the base material heating mechanism (not shown) provided with the halogen lamp arrange | positioned in the vapor deposition chamber 9 by making the pressure in the vapor deposition apparatus 6 into 1 * 10 < ^-3 > Pa. In addition to heating to 0 ° C., each of the Cu, In, and Ga material units arranged as the evaporation source B was heated to 1300 ° C., 1100 ° C., and 1100 ° C., respectively. In addition, the material unit of the evaporation source A was heated to 350 ° C., and the nozzle 12 was heated to 450 ° C.

  Then, the base material 1 is unwound from the unwinding roll 7 at a speed of 1 m / min, and travels in the vapor deposition chamber 9 toward the take-up roll 10. In addition to supplying Ga, In, and Cu derived from each material unit arranged in the above from the supply port 14 of the vapor deposition source B, Se is supplied in an injection state from the tip opening 13 of the nozzle 12 of the vapor deposition source A to have a chalcopyrite structure. The CIGS light absorption layer 3 was continuously formed on the surface of the substrate 1 on which the back electrode layer 2 was formed. Furthermore, in order to improve the crystallinity of the CIGS light absorption layer 3, the CIGS light absorption layer 3 is baked at a temperature of 550 ° C. for 15 minutes by a baking mechanism (not shown) provided in the vapor deposition chamber 9. Then, it was wound up by the winding roll 10 in the winding chamber 11.

(Manufacture of CIGS solar cells)
The substrate 1 on which the back electrode layer 2 and the CIGS light absorption layer 3 were formed in this order was unwound from the winding roll 10 and cut with a cutting device every 100 mm. And the buffer layer 4 (thickness 50 micrometers) which consists of CdS was formed in the surface in which the CIGS light absorption layer 3 of this cut | disconnected base material 1 was formed by CBD method. Further, a ZnO layer (thickness: 100 nm) and an ITO layer (thickness: 300 nm) were formed in this order on the buffer layer 4 by a sputtering method to obtain a surface electrode layer 5. And the comb-shaped electrode which consists of NiCr / Al was formed in the back surface (opposite surface where the CIGS light absorption layer 3 grade | etc., Was formed) of the base material 1, and the CIGS solar cell was completed.

[Example 2]
As shown in FIG. 6, as the nozzle 12 of the evaporation source A, a nozzle bifurcated into two is used, and Se is supplied in an injection state from two directions by this bifurcated nozzle. In the same manner as in Example 1, a CIGS solar cell was produced.

[Examples 3-12] and [Comparative Example 1], [Comparative Examples 3-8]
Other than changing the arrangement so that the tip opening 13 of the nozzle 12 of the vapor deposition source A, the supply port 14 of the vapor deposition source B, and the substrate 1 have the relationships shown in [Table 1] to [Table 4] below. Produced a CIGS solar cell in the same manner as in Example 1.

[Comparative Example 2]
While supplying Se from the vapor deposition source A without using the nozzle 12, the supply port of the vapor deposition source A and the base material 1 are changed their positions so as to have the relationship shown in Table 4, a virtual line showing the direction of supplying Se from the supply port of the evaporation source a, the intersection of the imaginary line I ₂ were changed so that from the substrate 1 surface and the position distant 10 mm (-10 mm downwards) upwardly other Produced a CIGS solar cell in the same manner as in Example 1.

Twenty CIGS solar cells of the above examples and comparative examples were manufactured, and their conversion efficiency was measured according to the following procedure. In addition, in the CIGS light absorption layer 3 in the above examples and comparative examples, the surface of a base material (width 30 nm, length 100 m, thickness 50 μm) prepared separately from ferrite SUS430 in order to evaluate the degree of wraparound of Se In addition, under the same conditions as those for forming the CIGS light absorption layer 3 in each of the examples and comparative examples, only Se and In were vapor-deposited, and a test material in which a vapor-deposited layer composed of Se and In was laminated was produced. And the composition ratio of Se / In in the vapor deposition layer of this test material was computed in accordance with the following procedure.
The measured and calculated results are also shown in the following [Table 1] to [Table 4].

〔Conversion efficiency〕
Pseudo sunlight (AM1.5) was irradiated to each 20 pieces of the CIGS solar cells of the above-mentioned examples and comparative examples so as to have an irradiation area of 100 mm square or more, and the conversion efficiency was measured with a solar simulator (cell tester YSS- 150, manufactured by Yamashita Denso Co., Ltd.). And the average conversion efficiency of the CIGS solar cell of each Example and a comparative example was computed. In addition, the said measurement was performed on the conditions of irradiance 1kW / m < ² > and battery temperature 25 degreeC.

[Se / In composition ratio]
About the vapor deposition layer of each test material produced above, using an energy dispersive X-ray fluorescence apparatus (EX-250, manufactured by HORIBA, Ltd.), the atomic number concentrations of Se and In elements are measured, and the atomic number concentrations thereof. Based on the above, the Se / In composition ratio of the vapor deposition layer was calculated.

  From the above results, in Examples 1 to 12, the Se / In composition ratio in the vapor deposition layer of the test material is all 1.36 or higher, and by using the vapor deposition method of the present invention, Even when the distance to the vapor deposition source was close, Se could sufficiently wrap around In, indicating that the reaction between Se and In was sufficiently performed. In order to support this, the CIGS solar cells of Examples 1 to 12 in which the CIGS light absorption layer 3 is formed by the vapor deposition method of the present invention have a high conversion efficiency of 11.8% or more. It was. On the other hand, Se is supplied from the evaporation source A using a nozzle, but the positional relationship between the nozzle tip opening, the supply port of the evaporation source B, and the substrate is out of the scope of the present invention. In Comparative Example 1, the Se / In composition ratio in the vapor deposition layer of the test material was as extremely low as 0.22, and the CIGS solar cell did not generate power. Further, in Comparative Example 2 in which the CIGS light absorption layer 3 is formed by a conventional vapor deposition method (no nozzle is used for supplying Se from the vapor deposition source A), the composition ratio of Se / In in the vapor deposition layer of the test material Was as low as 0.92, and the conversion efficiency of the CIGS solar cell was as low as 9.1%. Further, in Comparative Examples 3 to 8 in which the tip opening of the nozzle of the vapor deposition source A, the supply port of the vapor deposition source B, and the base material are not arranged at the positions satisfying the general formulas (1) to (4), Se / The composition ratio of In was not good, and the conversion efficiency of the CIGS solar cell was low.

  The method for producing a compound solar cell of the present invention is suitable for stably producing a compound solar cell having high conversion efficiency at a high speed.

DESCRIPTION OF SYMBOLS 1 Base material 12 Nozzle 13 Tip opening 14 Supply port A Deposition source B Deposition source

Claims (4)

A method of manufacturing a compound solar cell in which a compound semiconductor layer is formed on a base material by vapor deposition while running a long base material, and the formation of the compound semiconductor layer is supplied with a group VI element material The vapor deposition source A provided with a nozzle for the purpose and the vapor deposition source B provided with a supply port for supplying other elemental materials are used, and the supply port for the vapor deposition source B is separated from the substrate by 5 to 70 mm. In addition, the tip opening of the nozzle of the vapor deposition source A, the supply port of the vapor deposition source B, and the substrate are arranged at positions satisfying the following general formulas (1) to (4), and the group VI element A method for producing a compound solar cell, wherein the material is supplied in a sprayed state while being heated from the tip opening of the nozzle of the vapor deposition source A.
L ₁ / sin θ ₁ ≦ L ₂ / sin θ ₂ (1)
0 ° ≦ θ ₁ ≦ 30 ° (2)
θ ₁ ≦ θ ₂ ≦ 90 ° (3)
L ₁ <L ₂ (4)
θ ₁ : Angle (°) formed by a virtual line I ₁ indicating the ejection direction of the group VI element material from the tip opening of the nozzle of the evaporation source A and the base material
θ ₂ : Angle (°) formed by a virtual line I ₂ indicating the supply direction of elemental material other than the group VI from the supply port of the evaporation source B and the base material
L ₁ : Shortest distance (mm) between the nozzle tip opening of the evaporation source A and the substrate surface
L ₂ : The shortest distance (mm) between the supply port of the evaporation source B and the substrate surface   The method for producing a compound solar cell according to claim 1, wherein the compound semiconductor layer has a chalcopyrite structure composed of elements of Group I, Group III, and Group VI.   The nozzle attached to the vapor deposition source A is formed into a plurality of branched nozzles, and the group VI element material is supplied in a sprayed state from multiple directions by the plurality of branched nozzles. A method for producing a compound solar cell according to 1 or 2.   The compound semiconductor layer is formed in a vacuum chamber, and a nozzle for injecting the group VI element material is disposed in the vacuum chamber and connected to the nozzle by a detachable valve means. The deposited vapor deposition source A is disposed outside the vacuum chamber, and the group VI element material is supplied from the vapor deposition source A to a nozzle in the vacuum chamber. The manufacturing method of the compound solar cell as described in any one of.

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