CN112640133B - Solar cell manufacturing method, solar cell, and solar cell module - Google Patents

Abstract

The invention provides a method for manufacturing a solar cell, which can simplify the formation of a transparent electrode layer. The method for manufacturing the solar cell sequentially comprises the following steps: a conductive semiconductor layer (25, 35) is formed on the back surface side of a substrate (11), a transparent conductive film is formed on the conductive semiconductor layer (25, 35), metal electrode layers (29, 39) are formed on the conductive semiconductor layer (25, 35) through the transparent conductive film, and transparent electrode layers (28, 38) separated from each other are formed by patterning the transparent conductive film. In the metal electrode layer forming step, a printing material containing a metal material, a resin material and a solvent is printed and cured to form metal electrode layers (29, 39), and a resin film (40) in which the resin material is present in a biased state is formed at the peripheral edges of the metal electrode layers (29, 39), and in the transparent electrode layer forming step, the transparent conductive film is patterned using the metal electrode layer (29) and the resin film (40) at the peripheral edges thereof and the metal electrode layer (39) and the resin film (40) at the peripheral edges thereof as masks.

Description

Manufacturing method of solar cell, solar cell and solar cell module

Technical field

The present invention relates to a method for manufacturing a back electrode type (back contact type) solar cell, a back electrode type solar cell, and a solar cell module including the solar cell.

Background technique

Solar cells using a semiconductor substrate include double-sided electrode solar cells in which electrodes are formed on both the light-receiving surface side and the back side, and back electrode type solar cells in which electrodes are formed only on the back side. In a double-sided electrode type solar cell, an electrode is formed on the light-receiving surface side, so sunlight is blocked by the electrode. On the other hand, in a back electrode type solar cell, since no electrode is formed on the light-receiving surface side, the solar light reception rate is higher compared to a double-surface electrode type solar cell. Patent Document 1 discloses a back electrode type solar cell.

The solar cell described in Patent Document 1 includes a semiconductor substrate, a first conductive semiconductor layer and a first electrode layer sequentially stacked on the back side of the semiconductor substrate, and a second conductive layer sequentially stacked on another part of the back side of the semiconductor substrate. type semiconductor layer and the second electrode layer. To prevent short circuit, the first electrode layer and the second electrode layer are separated from each other.

Patent Document 1: Japanese Patent Application Publication No. 2013-131586

Usually, the first electrode layer and the second electrode layer include a transparent electrode layer and a metal electrode layer respectively. The metal electrode layer can be relatively easily separated and formed by, for example, a screen printing method using silver paste. On the other hand, the transparent electrode layer needs to be separated and formed by, for example, photolithography using a mask, and the formation process is relatively complicated.

Contents of the invention

An object of the present invention is to provide a solar cell manufacturing method, a solar cell, and a solar cell module that can simplify the formation of a transparent electrode layer.

A method of manufacturing a solar cell according to the present invention is a method of manufacturing a back electrode type solar cell. The back electrode type solar cell includes a semiconductor substrate having two main surfaces, and a third electrode disposed on one main surface side of the semiconductor substrate. A conductive semiconductor layer and a second conductive semiconductor layer, a first transparent electrode layer and a first metal electrode layer corresponding to the first conductive semiconductor layer, and a second transparent electrode layer corresponding to the second conductive semiconductor layer, and For the second metal electrode layer, the manufacturing method of the above-mentioned solar cell sequentially includes: a semiconductor layer forming step of forming a first conductive type semiconductor layer on a part of one main surface side of the semiconductor substrate, and forming a first conductive type semiconductor layer on the other part of one main surface side of the semiconductor substrate. a second conductive type semiconductor layer; a transparent conductive film forming step of forming a transparent conductive film across the first conductive type semiconductor layer and a second conductive type semiconductor layer; and a metal electrode layer forming step of forming a transparent conductive film across the first conductive type semiconductor layer and the second conductive type semiconductor layer forming a first metal electrode layer on the first conductive type semiconductor layer, forming a second metal electrode layer on the second conductive type semiconductor layer via the transparent conductive film; and a transparent electrode layer forming step of patterning the transparent conductive film, In this way, the first transparent electrode layer and the second transparent electrode layer that are separated from each other are formed. In the metal electrode layer forming step, a printing material including a granular metal material, a resin material, and a solvent is printed and solidified, thereby forming the first transparent electrode layer. The metal electrode layer and the second metal electrode layer form a resin film in which the resin material is biasedly present on the periphery of the first metal electrode layer and the periphery of the second metal electrode layer. In the transparent electrode layer forming process, the first metal is used. The electrode layer and the resin film on its periphery and the second metal electrode layer and the resin film on its periphery are used as masks to pattern the transparent conductive film.

The solar cell according to the present invention is a back electrode type solar cell and includes a semiconductor substrate having two main surfaces, a first conductive type semiconductor layer and a second conductive type semiconductor layer arranged on one main surface side of the semiconductor substrate. The first transparent electrode layer and the first metal electrode layer corresponding to the first conductive type semiconductor layer, and the second transparent electrode layer and the second metal electrode layer corresponding to the second conductive type semiconductor layer, the first transparent electrode layer and the second metal electrode layer corresponding to the second conductive type semiconductor layer. A metal electrode layer is in the shape of a strip. The bandwidth of the first transparent electrode layer is narrower than the bandwidth of the first metal electrode layer. The second transparent electrode layer and the second metal electrode layer are in the shape of a strip. The bandwidth of the second transparent electrode layer is narrower than the bandwidth of the second transparent electrode layer. The metal electrode layer has a narrow bandwidth, and the resin material in the printing material in which the first metal electrode layer and the second metal electrode layer are formed on the periphery of the first metal electrode layer and the second metal electrode layer is distributed in a biased manner. membrane.

A solar cell module according to the present invention includes the above-mentioned solar cell.

According to the present invention, the formation of the transparent electrode layer of the solar cell can be simplified.

Description of the drawings

FIG. 1 is a side view showing an example of the solar cell module according to this embodiment.

FIG. 2 is a view of the solar cell according to the present embodiment as viewed from the back side.

FIG. 3 is a cross-sectional view of the solar cell of FIG. 2 taken along line III-III.

FIG. 4A is a diagram showing a semiconductor layer forming step in the solar cell manufacturing method according to this embodiment.

FIG. 4B is a diagram showing a transparent conductive film forming step in the solar cell manufacturing method according to this embodiment.

4C is a diagram showing a metal electrode layer forming step in the solar cell manufacturing method according to this embodiment.

FIG. 4D is a diagram showing a transparent electrode layer forming step in the solar cell manufacturing method according to this embodiment.

FIG. 5A is the result of observing the metal electrode layer and the space between the metal electrode layers on the back side of the solar cell of the Example using an SEM at a magnification of 100 times.

FIG. 5B is the result of observing the portion A between the metal electrode layers in FIG. 5A using an SEM at a magnification of 450 times.

FIG. 5C is a result of observing the portion B between the metal electrode layers in FIG. 5B using an SEM at a magnification of 5000 times.

Detailed ways

Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. In addition, in each drawing, the same or corresponding parts are given the same reference numerals. In addition, hatching, component reference signs, etc. may be omitted for convenience. In such cases, refer to other drawings.

(solar cell module)

FIG. 1 is a side view showing an example of the solar cell module according to this embodiment. The solar cell module 100 includes a plurality of solar cell units 1 arranged two-dimensionally.

The solar battery cells 1 are connected in series and/or in parallel via the wiring member 2 . Specifically, the wiring member 2 is connected to a bus bar portion (described later) in the electrode layer of the solar cell 1 . The wiring member 2 is, for example, a known interconnector such as a lug.

The solar cell unit 1 and the wiring member 2 are sandwiched between the light-receiving surface protection member 3 and the back surface protection member 4 . The liquid or solid sealing material 5 is filled between the light-receiving surface protection member 3 and the back surface protection member 4, whereby the solar cell unit 1 and the wiring member 2 are sealed. The light-receiving surface protection member 3 is, for example, a glass substrate, and the back surface protection member 4 is a glass substrate or a metal plate. The sealing material 5 is, for example, transparent resin.

Hereinafter, the solar cell unit (hereinafter, referred to as a solar cell) 1 will be described in detail.

(Solar battery)

FIG. 2 is a view of the solar cell according to the present embodiment as viewed from the back side. The solar cell 1 shown in FIG. 2 is a back electrode type solar cell. The solar cell 1 includes a semiconductor substrate 11 having two main surfaces, and the semiconductor substrate 11 has a first conductive type region 7 and a second conductive type region 8 on the main surface.

The first conductivity type region 7 has a so-called comb shape and has a plurality of finger portions 7f corresponding to comb teeth and a busbar portion 7b corresponding to a support portion of the comb teeth. The bus bar portion 7b extends in a first direction (X direction) along one edge of the semiconductor substrate 11, and the finger portion 7f extends from the bus bar portion 7b in a second direction (Y direction) intersecting the first direction.

Similarly, the second conductivity type region 8 has a so-called comb-like shape and has a plurality of finger portions 8f corresponding to comb teeth and a busbar portion 8b corresponding to a support portion of the comb teeth. The bus bar portion 8 b extends in the first direction (X direction) along the other edge portion of the semiconductor substrate 11 that is opposite to one edge portion, and the finger portion 8 f extends in the second direction (Y direction) from the bus bar portion 8 b.

The finger portions 7f and 8f form a strip shape extending in the second direction (Y direction) and are alternately arranged in the first direction (X direction).

In addition, the first conductivity type region 7 and the second conductivity type region 8 may be formed in a stripe shape.

FIG. 3 is a cross-sectional view of the solar cell of FIG. 2 taken along line III-III. As shown in FIG. 3 , the solar cell 1 includes a passivation layer 13 laminated on the light-receiving surface side of the main surface that receives light among the main surfaces of the semiconductor substrate 11 . In addition, the solar cell 1 includes a passivation layer sequentially laminated on a part of the back side of the main surface (one main surface) opposite to the light-receiving surface of the semiconductor substrate 11 (mainly the first conductive type region 7 ). 23. The first conductive semiconductor layer 25 and the first electrode layer 27 . In addition, the solar cell 1 includes a passivation layer 33 , a second conductivity type semiconductor layer 35 , and a second electrode layer 37 that are sequentially stacked on the other part (mainly the second conductivity type region 8 ) on the back side of the semiconductor substrate 11 .

The semiconductor substrate 11 is made of a crystalline silicon material such as single crystal silicon or polycrystalline silicon. The semiconductor substrate 11 is, for example, an n-type semiconductor substrate in which crystalline silicon material is doped with an n-type dopant. In addition, the semiconductor substrate 11 may be a p-type semiconductor substrate in which a p-type dopant is doped into a crystalline silicon material, for example. An example of the n-type dopant is phosphorus (P). Examples of the p-type dopant include boron (B).

The semiconductor substrate 11 functions as a photoelectric conversion substrate that absorbs incident light from the light-receiving surface side and generates photogenerated carriers (electrons and holes).

Crystalline silicon is used as the material of the semiconductor substrate 11, so that even when the dark current is relatively small and the intensity of incident light is low, a high output (stable output that is not affected by illumination) can be obtained.

The semiconductor substrate 11 may have a pyramid-shaped minute uneven structure called a texture structure on the back side. This improves the recovery efficiency of light that passes through the semiconductor substrate 11 without being absorbed.

In addition, the semiconductor substrate 11 may have a pyramid-shaped minute uneven structure called a texture structure on the light-receiving surface side. This reduces reflection of incident light on the light-receiving surface, thereby improving the light confinement effect of the semiconductor substrate 11 .

The passivation layer 13 is formed on the light-receiving surface side of the semiconductor substrate 11 . The passivation layer 23 is formed in the first conductive type region 7 on the back side of the semiconductor substrate 11 . The passivation layer 33 is formed in the second conductive type region 8 on the back side of the semiconductor substrate 11 . The passivation layers 13, 23, and 33 are formed of, for example, intrinsic (i-type) amorphous silicon material.

The passivation layers 13, 23, and 33 suppress recoupling of carriers generated in the semiconductor substrate 11, thereby improving carrier recovery efficiency.

An anti-reflection layer made of a material such as SiO, SiN or SiON may also be provided on the passivation layer 13 on the light-receiving surface side of the semiconductor substrate 11 .

The first conductivity type semiconductor layer 25 is formed on the passivation layer 23 , that is, in the first conductivity type region 7 on the back side of the semiconductor substrate 11 . The first conductive type semiconductor layer 25 is formed of, for example, an amorphous silicon material. The first conductive type semiconductor layer 25 is, for example, a p-type semiconductor layer in which an amorphous silicon material is doped with a p-type dopant (for example, the above-mentioned boron (B)).

The second conductive type semiconductor layer 35 is formed on the passivation layer 33 , that is, in the second conductive type region 8 on the back side of the semiconductor substrate 11 . The second conductive semiconductor layer 35 is formed of, for example, an amorphous silicon material. The second conductive type semiconductor layer 35 is, for example, an n-type semiconductor layer in which an amorphous silicon material is doped with an n-type dopant (for example, the above-mentioned phosphorus (P)).

In addition, the first conductive type semiconductor layer 25 may be an n-type semiconductor layer, and the second conductive type semiconductor layer 35 may be a p-type semiconductor layer.

The first conductive type semiconductor layer 25 and the passivation layer 23 and the second conductive type semiconductor layer 35 and the passivation layer 33 form a strip extending along the second direction (Y direction), and alternate in the first direction (X direction). arrangement.

The second conductive type semiconductor layer 35 and a part of the passivation layer 33 may also overlap on a part of the adjacent first conductive type semiconductor layer 25 and the passivation layer 23 (illustration omitted).

The first electrode layer 27 corresponds to the first conductive type semiconductor layer 25 and is specifically formed on the first conductive type semiconductor layer 25 in the first conductive type region 7 on the back side of the semiconductor substrate 11 . The second electrode layer 37 corresponds to the second conductive type semiconductor layer 35 and is specifically formed on the second conductive type semiconductor layer 35 in the second conductive type region 8 on the back side of the semiconductor substrate 11 .

The first electrode layer 27 has a first transparent electrode layer 28 and a first metal electrode layer 29 that are sequentially stacked on the first conductive type semiconductor layer 25 . The second electrode layer 37 includes a second transparent electrode layer 38 and a second metal electrode layer 39 that are sequentially stacked on the second conductive type semiconductor layer 35 .

The first transparent electrode layer 28 and the second transparent electrode layer 38 are formed of a transparent conductive material. Examples of the transparent conductive material include ITO (Indium Tin Oxide: a composite oxide of indium oxide and tin oxide).

The first metal electrode layer 29 and the second metal electrode layer 39 are formed of a conductive paste material containing granular metal materials such as silver, copper, and aluminum, an insulating resin material, and a solvent.

The first electrode layer 27 and the second electrode layer 37, that is, the first transparent electrode layer 28, the second transparent electrode layer 38, the first metal electrode layer 29 and the second metal electrode layer 39 are formed to extend in the second direction (Y direction). strips, and are alternately arranged in the first direction (X direction).

The first transparent electrode layer 28 and the second transparent electrode layer 38 are separated from each other, and the first metal electrode layer 29 and the second metal electrode layer 39 are also separated from each other.

The bandwidth of the first transparent electrode layer 28 in the first direction (X direction) is narrower than the bandwidth of the first metal electrode layer 29 in the first direction (X direction). The bandwidth of the second transparent electrode layer 38 in the first direction (X direction) The bandwidth is narrower than the bandwidth of the second metal electrode layer 39 in the first direction (X direction).

A resin film 40 is formed on the periphery of the first metal electrode layer 29 and the second metal electrode layer 39 . The resin film 40 is formed by the conductive paste material of the first metal electrode layer 29 and the second metal electrode layer 39 . Insulating resin material exists in a biased manner (details will be described later).

A part of the first conductive type semiconductor layer 25 and a part of the second conductive type semiconductor layer 35 between the first metal electrode layer 29 and the second metal electrode layer 39 are covered with the resin film 40 . Specifically, the valleys of the uneven structure (textured structure) of the first conductive type semiconductor layer 25 and the valleys of the uneven structure of the second conductive type semiconductor layer 35 between the first metal electrode layer 29 and the second metal electrode layer 39 is covered with the resin film 40.

On the other hand, the top of the uneven structure of the first conductive type semiconductor layer 25 and the top of the uneven structure of the second conductive type semiconductor layer 35 between the first metal electrode layer 29 and the second metal electrode layer 39 are not covered by the resin film 40 Covered and exposed.

Between the first conductive semiconductor layer 25 and the resin film 40 and between the second conductive semiconductor layer 35 and the resin film 40, the first transparent electrode layer 28 and the second transparent electrode layer 28 are arranged in an island shape (discontinuously). The transparent conductive film 48 is made of the same material as the transparent electrode layer 38 . Specifically, they are arranged in an island shape between the valleys of the uneven structure of the first conductive type semiconductor layer 25 and the resin film 40 and between the valleys of the uneven structure of the second conductive type semiconductor layer 35 and the resin film 40 There is a transparent conductive film 48.

The contact area between the first metal electrode layer 29 and the first conductive type semiconductor layer 25 is less than half of the contact area between the first transparent electrode layer 28 and the first conductive type semiconductor layer 25. The contact area of the semiconductor layer 35 is less than half of the contact area between the second transparent electrode layer 38 and the second conductive type semiconductor layer 35 .

Next, a method of manufacturing a solar cell according to this embodiment will be described with reference to FIGS. 4A to 4D . 4A is a diagram showing a semiconductor layer forming step in the solar cell manufacturing method according to this embodiment, and FIG. 4B is a diagram showing a transparent conductive film forming step in the solar cell manufacturing method according to this embodiment. 4C is a diagram showing a metal electrode layer forming step in the solar cell manufacturing method according to this embodiment, and FIG. 4D is a diagram showing a transparent electrode layer forming step in the solar cell manufacturing method according to this embodiment. In FIGS. 4A to 4D , the back side of the semiconductor substrate 11 is shown, and the front side of the semiconductor substrate 11 is omitted.

First, as shown in FIG. 4A , the passivation layer 23 and the first conductivity type are formed on a part of the back side of the semiconductor substrate 11 having an uneven structure (texture structure) at least on the back side, specifically in the first conductivity type region 7 . Semiconductor layer 25 (semiconductor layer forming step).

For example, a passivation film and a first conductive type semiconductor film may be formed on the entire back side of the semiconductor substrate 11 using a CVD method or a PVD method, and then a mask or a metal mask generated by photolithography may be used. The passivation layer 23 and the first conductive type semiconductor layer 25 are patterned by etching. Examples of the etching solution for the p-type semiconductor film include an acidic solution such as ozone-containing hydrofluoric acid or a mixture of nitric acid and hydrofluoric acid. Examples of the etching solution for the n-type semiconductor film include hydroxide. An alkaline solution such as potassium aqueous solution.

Alternatively, when the passivation layer and the first conductive type semiconductor layer are stacked on the back side of the semiconductor substrate 11 using the CVD method or the PVD method, the passivation layer 23 and the p-type semiconductor layer 25 may be formed simultaneously using a mask. and pattern forming.

Next, the passivation layer 33 and the second conductivity type semiconductor layer 35 are formed on the other part on the back side of the semiconductor substrate 11 , specifically in the second conductivity type region 8 (semiconductor layer forming step).

For example, in the same manner as described above, the passivation film and the second conductive type semiconductor film may be formed on the entire back side of the semiconductor substrate 11 using the CVD method or the PVD method, and then using a mask generated by photolithography technology or the like. The passivation layer 33 and the second conductive type semiconductor layer 35 are patterned using a metal mask etching method.

Alternatively, when the passivation layer and the second conductive type semiconductor layer are stacked on the back side of the semiconductor substrate 11 using the CVD method or the PVD method, the passivation layer 33 and the second conductive type semiconductor layer 35 may be layered simultaneously using a mask. Film forming and pattern forming.

In addition, in this semiconductor layer forming step, the passivation layer 13 (not shown) may be formed on the entire surface on the light-receiving surface side of the semiconductor substrate 11 .

Next, as shown in FIG. 4B , a transparent conductive film 28Z is formed on the first conductive type semiconductor layer 25 and the second conductive type semiconductor layer 35 so as to span them (transparent conductive film forming step). As a method of forming the transparent conductive film 28Z, for example, a CVD method, a PVD method, or the like is used.

Next, as shown in FIG. 4C , the first metal electrode layer 29 is formed on the first conductive type semiconductor layer 25 via the transparent conductive film 28Z, and the second metal electrode layer 29 is formed on the second conductive type semiconductor layer 35 via the transparent conductive film 28Z. Metal electrode layer 39 (metal electrode layer forming step).

The first metal electrode layer 29 and the second metal electrode layer 39 are formed by printing a printing material (for example, ink). Examples of methods for forming the first metal electrode layer 29 and the second metal electrode layer 39 include a screen printing method, an inkjet method, a gravure coating method, a dispensing method, and the like. Among them, the screen printing method is preferred.

The printing material contains a granular (for example, spherical) metal material in an insulating resin material. The printing material may contain a solvent or the like in order to adjust the viscosity or coating properties.

Examples of the insulating resin material include matrix resin and the like. Specifically, as the insulating resin, a polymer compound is preferred, and a thermosetting resin or an ultraviolet curing resin is particularly preferred. Typical examples include epoxy, polyurethane, polyester, and silicone-based resins.

Examples of metal materials include silver, copper, aluminum, and the like. Among these, a silver paste containing silver particles is preferred.

For example, the proportion of the metal material contained in the printing material is 85% or more and 95% or less based on the weight ratio of the entire printing material.

Next, after the first metal electrode layer 29 and the second metal electrode layer 39 are printed, the insulating resin in the first metal electrode layer 29 and the second metal electrode layer 39 is cured by heat treatment or ultraviolet irradiation treatment. At this time, the insulating resin material exudes to the periphery of the first metal electrode layer 29 and the second metal electrode layer 39 , and forms an insulating resin on the periphery of the first metal electrode layer 29 and the second metal electrode layer 39 . The resin film 40 in which the material exists in a biased manner.

At this time, the valley portions of the uneven structure (texture structure) of the transparent conductive film 28Z between the first metal electrode layer 29 and the second metal electrode layer 39 are covered with the resin film 40 . On the other hand, the top of the uneven structure of the transparent conductive film 28Z between the first metal electrode layer 29 and the second metal electrode layer 39 is not covered by the resin film 40 and is exposed.

In addition, the first metal electrode layer 29 and the second metal electrode layer 39 formed of the conductive paste as described above may have urethane bonds. For example, compared with epoxy resin, polyurethane resin shrinks less during cross-linking and is less prone to cracks in the resin. If cracks are less likely to occur in the resin, the etching solution can be prevented from penetrating into the metal electrode layer, thereby preventing the transparent conductive film under the metal electrode layer from being etched, causing the metal electrode layer to peel off and deteriorate long-term reliability.

Next, as shown in FIG. 4D , the transparent conductive film is etched using an etching method using the first metal electrode layer 29 and its peripheral resin film 40 and the second metal electrode layer 39 and its peripheral resin film 40 as masks. 28Z performs patterning to form the first transparent electrode layer 28 and the second transparent electrode layer 38 that are separated from each other (transparent electrode layer forming step). Examples of the etching method include wet etching, and examples of the etching solution include acidic solutions such as hydrochloric acid (HCl).

At this time, etching of the transparent conductive film 28Z proceeds from the top of the uneven structure (texture structure) toward the valley portion between the first metal electrode layer 29 and the second metal electrode layer 39 .

Here, in order to separate the first transparent electrode layer 28 and the second transparent electrode layer 38, the transparent conductive film between them only needs to be discontinuous, and the transparent conductive film 48 may remain in the valleys of the uneven structure in an island shape. If the transparent conductive film 48 remains in the valley portion of the uneven structure in an island shape, the resin film 40 in the valley portion of the uneven structure remains on the first conductive type semiconductor layer 25 and the second conductive type semiconductor layer 35 .

Through the above steps, the back electrode type solar cell 1 of this embodiment is completed.

Here, the conventional solar cell manufacturing method includes a transparent electrode layer forming step after the transparent conductive film forming step and before the metal electrode layer forming step.

In the transparent electrode layer forming process, the transparent conductive film is patterned using, for example, photolithography, thereby forming a first transparent electrode layer and a second transparent electrode layer that are separated from each other. In photolithography,

·Coat resist on the transparent conductive film,

・By sensitizing the resist to light, openings are formed in the resist,

·Etching the transparent conductive film exposed in the opening using the resist as a mask to form a first transparent electrode layer and a second transparent electrode layer that are separated from each other,

·Remove the resist.

In contrast, according to the solar cell manufacturing method of this embodiment, after the transparent conductive film forming step, the metal electrode layer forming step and the transparent electrode layer forming step are sequentially included. In the transparent electrode layer forming step, a metal electrode layer is formed by using The first metal electrode layer 29 and the second metal electrode layer 39 formed in the forming step are used as masks to pattern the transparent conductive film 28Z, thereby forming the first transparent electrode layer 28 and the second transparent electrode layer 38 that are separated from each other. Therefore, according to the solar cell manufacturing method of this embodiment, it is possible to simplify and shorten the formation of the transparent electrode layer without using photolithography using a mask as in the past. As a result, the cost of solar cells and solar cell modules can be reduced.

Here, if the first metal electrode layer 29 and the second metal electrode layer 39 are used as masks to pattern the transparent conductive film 28Z, during etching of the transparent conductive film 28Z, the first metal electrode layer 29 and the second metal electrode layer 29 are etched. The transparent conductive film 28Z under the electrode layer 39 is also etched, so there is a possibility that the first transparent electrode layer 28 and the first metal electrode layer 29 are peeled off from the second transparent electrode layer 38 and the second metal electrode layer 39 .

In this regard, according to the solar cell manufacturing method of this embodiment, in the metal electrode layer forming step, a printing material containing a granular metal material, a resin material, and a solvent is printed and solidified, so that the first metal electrode layer is formed on the first metal electrode layer. A resin film 40 in which resin material exists in a biased manner is formed on the periphery of 29 and the periphery of the second metal electrode layer 39. In the transparent electrode layer forming process, the first metal electrode layer 29 and the resin film 40 on its periphery and the second metal electrode layer 39 are used. The metal electrode layer 39 and the resin film 40 on its periphery serve as a mask to pattern the transparent conductive film 28Z. This can suppress the etching of the transparent conductive film 28Z under the first metal electrode layer 29 and the second metal electrode layer 39, thereby suppressing the separation of the first transparent electrode layer 28 and the first metal electrode layer 29 from the second transparent electrode. The layer 38 and the second metal electrode layer 39 are peeled off.

In the solar cell 1 manufactured by such a manufacturing method, the bandwidth of the first transparent electrode layer 28 is narrower than the bandwidth of the first metal electrode layer 29 , and the bandwidth of the second transparent electrode layer 38 is smaller than the bandwidth of the second metal electrode layer 39 . Narrow, a resin film in which the resin material in the printing material in which the first metal electrode layer 29 and the second metal electrode layer 39 are formed on the periphery of the first metal electrode layer 29 and the second metal electrode layer 39 is biased. .

In addition, in solar cells manufactured by conventional solar cell manufacturing methods, the bandwidth of the transparent electrode layer is generally wider than the bandwidth of the metal electrode layer.

In addition, in the solar cell 1 manufactured by the manufacturing method of this embodiment, a part of the first conductive type semiconductor layer 25 and the second conductive type semiconductor layer between the first metal electrode layer 29 and the second metal electrode layer 39 A part of 35 is covered with the resin film 40. Specifically, the valleys of the uneven structure (textured structure) of the first conductive type semiconductor layer 25 and the valleys of the uneven structure of the second conductive type semiconductor layer 35 between the first metal electrode layer 29 and the second metal electrode layer 39 is covered with the resin film 40.

In addition, between the first conductive type semiconductor layer 25 and the resin film 40 and between the second conductive type semiconductor layer 35 and the resin film 40, the first transparent electrode layer 28 and the first transparent electrode layer 28 are arranged in an island shape (discontinuously). The second transparent electrode layer 38 is made of the same material as the transparent conductive film 48 . Specifically, they are arranged in an island shape between the valleys of the uneven structure of the first conductive type semiconductor layer 25 and the resin film 40 and between the valleys of the uneven structure of the second conductive type semiconductor layer 35 and the resin film 40 There is a transparent conductive film 48.

As a result, the exposed areas of the first conductive type semiconductor layer 25 and the second conductive type semiconductor layer 35 become smaller. Therefore, deterioration of the solar cell and the solar cell module can be suppressed, thereby improving the reliability (for example, long-term durability) of the solar cell and the solar cell module.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various changes and modifications are possible. For example, in the above-described embodiment, a heterojunction type solar cell 1 is illustrated as shown in FIG. 3 . However, the present invention is not limited to heterojunction type solar cells and can also be applied to homojunction type solar cells. Various solar cells.

In addition, in the above-mentioned embodiment, the solar cell having the crystalline silicon substrate was exemplified, but the solar cell is not limited to this. For example, a solar cell may also have a gallium arsenide (GaAs) substrate.

Example

Hereinafter, the present invention will be specifically described based on Examples, but the present invention is not limited to the following Examples.

As described below, the solar cell 1 shown in FIGS. 2 and 3 is produced according to the steps shown in FIGS. 4A to 4D .

First, the back side of the single crystal silicon substrate is anisotropically etched to obtain the semiconductor substrate 11 having a pyramid-shaped texture structure formed on the back side.

Next, after forming a passivation film and a first conductive type semiconductor film on the entire back side of the semiconductor substrate 11 using the CVD method, etching using a photoresist (mask) generated by the photolithography technology is used. method, the passivation layer 23 and the first conductive type semiconductor layer 25 are formed on a part of the back side of the semiconductor substrate 11 (semiconductor layer forming step).

Next, after forming a passivation film and a second conductive type semiconductor film on the entire back side of the semiconductor substrate 11 using the CVD method, etching using a photoresist (mask) generated by the photolithography technology is used. method, the passivation layer 33 and the second conductive type semiconductor layer 35 are formed on the other part on the back side of the semiconductor substrate 11 (semiconductor layer forming step).

Next, using the CVD method, the transparent conductive film 28Z is formed on the first conductive type semiconductor layer 25 and the second conductive type semiconductor layer 35 so as to span them (transparent conductive film forming step).

Next, using the screen printing method using silver paste, the first metal electrode layer 29 is formed on the first conductive type semiconductor layer 25 through the transparent conductive film 28Z, and the second conductive type semiconductor layer is formed through the transparent conductive film 28Z. A second metal electrode layer 39 is formed on 35 (metal electrode layer forming step).

Then, the first metal electrode layer 29 and the second metal electrode layer 39 were heat-treated in an oven at 180° C. for 1 hour. As a result, the insulating resin material in the printing material bleeds out to the periphery of the first metal electrode layer 29 and the second metal electrode layer 39 , so that the insulating resin material in the first metal electrode layer 29 and the second metal electrode layer 39 The resin film 40 is formed on the periphery of the resin film 40 .

Next, the transparent conductive film 28Z is patterned using an etching method using the first metal electrode layer 29 and its peripheral resin film 40 and the second metal electrode layer 39 and its peripheral resin film 40 as masks. This forms the first transparent electrode layer 28 and the second transparent electrode layer 38 that are separated from each other (transparent electrode layer forming step). As the etching solution, hydrochloric acid (HCl) is used.

In the process of manufacturing the solar cell of the Example as described above, the transparent conductive film formation process and the metal electrode layer formation process were observed using SEM (field emission scanning electron microscope S4800, manufactured by Hitachi High-Technology Corporation) and the transparent electrode layer was observed The back side of the solar cell before the forming process. The results are shown in Figures 5A to 5C.

Figure 5A is the result of observing the metal electrode layer and the space between the metal electrode layers on the back side of the solar cell of the Example using an SEM at a magnification of 100 times. Figure 5B is an observation of the space between the metal electrode layers in Figure 5A using a SEM at a magnification of 450 times. Results of Part A. FIG. 5C is a result of observing the portion B between the metal electrode layers in FIG. 5B using an SEM at a magnification of 5000 times.

According to FIGS. 5A to 5C , it can be confirmed that a resin film 40 (black portion) in which an insulating resin material exists in a biased manner is formed on the periphery of the first metal electrode layer 29 and the periphery of the second metal electrode layer 39 .

In addition, it can be confirmed that the valley portions of the uneven structure (texture structure) of the transparent conductive film 28Z between the first metal electrode layer 29 and the second metal electrode layer 39 are covered with the resin film 40 (black portion). On the other hand, it can be confirmed that the top of the uneven structure of the transparent conductive film 28Z between the first metal electrode layer 29 and the second metal electrode layer 39 is not covered by the resin film 40 and is exposed. Therefore, it is expected that in the subsequent etching of the transparent electrode layer forming step, the etching of the transparent conductive film 28Z proceeds from the top toward the bottom of the uneven structure.

Next, after the transparent electrode layer forming process, the back side of the solar cell of the example produced was observed using SEM, and it was confirmed that the first transparent electrode layer 28 and the first metal electrode layer 29 and the second transparent electrode layer 38 and the second transparent electrode layer 38 were confirmed. The two metal electrode layers 39 are not peeled off. In addition, it was confirmed that the resin film 40 was not peeled off and remained in the valley portion of the uneven structure between the first metal electrode layer 29 and the second metal electrode layer 39 .

In addition, short circuit inspection between electrodes was performed, and it was confirmed that there was no short circuit between electrode layers.

Since the resin film 40 has not been peeled off and there is no short circuit between the electrode layers, it is expected that the transparent conductive film 48 remains in an island shape between the valleys of the uneven structure of the first conductive type semiconductor layer 25 and the resin film 40 and between the second conductive layers. The resin film 40 is held between the valleys of the concave-convex structure of the semiconductor layer 35 and the resin film 40 .

Explanation of reference signs

1...Solar cell; 2...Wiring components; 3...Light-receiving surface protection component; 4...Back surface protection component; 5...Sealing material; 7...First conductivity type area; 8...Second conductivity type area; 7b, 8b...Busbar section ; 7f, 8f...finger; 11...semiconductor substrate; 13, 23, 33...passivation layer; 25...first conductive type semiconductor layer; 27...first electrode layer; 28...first transparent electrode layer; 28Z...transparent Conductive film; 29... first metal electrode layer; 35... second conductive semiconductor layer; 37... second electrode layer; 38... second transparent electrode layer; 39... second metal electrode layer; 40... resin film; 48... Transparent conductive film; 100...solar cell module.

Claims (13)

1. A method of manufacturing a solar cell, which is a method of manufacturing a back electrode type solar cell. The back electrode type solar cell includes: a semiconductor substrate having two main surfaces; and a main surface arranged on the semiconductor substrate. The first conductive type semiconductor layer and the second conductive type semiconductor layer on the surface side, the first transparent electrode layer and the first metal electrode layer corresponding to the first conductive type semiconductor layer, and the second conductive type semiconductor layer The corresponding second transparent electrode layer and second metal electrode layer, The solar cell manufacturing method is characterized in that it includes: A semiconductor layer forming step of forming the first conductive type semiconductor layer on a part of the one main surface side of the semiconductor substrate, and forming the second conductive type semiconductor layer on the other part of the one main surface side of the semiconductor substrate. type semiconductor layer; A transparent conductive film forming step of forming a transparent conductive film on the first conductive type semiconductor layer and the second conductive type semiconductor layer across them; A metal electrode layer forming step is to form the first metal electrode layer on the first conductive type semiconductor layer through the transparent conductive film, and to form the first metal electrode layer on the second conductive type semiconductor layer through the transparent conductive film. the second metal electrode layer; and a transparent electrode layer forming step of patterning the transparent conductive film to form the first transparent electrode layer and the second transparent electrode layer that are separated from each other, In the metal electrode layer forming process, a printing material including a granular metal material, a resin material, and a solvent is printed and solidified, thereby forming the first metal electrode layer and the second metal electrode layer. The periphery of the first metal electrode layer and the periphery of the second metal electrode layer form a resin film in which the resin material exists in a biased manner, In the transparent electrode layer forming process, the first metal electrode layer and the resin film on its periphery and the second metal electrode layer and the resin film on its periphery are used as masks to form the transparent electrode layer. The transparent conductive film is patterned. 2. The manufacturing method of solar cells according to claim 1, characterized in that, In the transparent electrode layer forming step, the transparent conductive film is patterned using a wet etching method using an etching solution. 3. The manufacturing method of solar cells according to claim 1, characterized in that, In the metal electrode layer forming process, the printing material is printed using a screen printing method. 4. The method for manufacturing a solar cell according to any one of claims 1 to 3, characterized in that: The proportion of the metal material contained in the printing material is 85% or more and 95% or less based on the weight ratio of the entire printing material. 5. A solar cell, which is a back electrode type solar cell, including a semiconductor substrate having two main surfaces, a first conductive type semiconductor layer and a second conductive type semiconductor layer arranged on one main surface side of the semiconductor substrate. a semiconductor layer, a first transparent electrode layer and a first metal electrode layer corresponding to the first conductive type semiconductor layer, and a second transparent electrode layer and a second metal electrode layer corresponding to the second conductive type semiconductor layer, The solar cell is characterized by: The first transparent electrode layer and the first metal electrode layer are in a strip shape, and the bandwidth of the first transparent electrode layer is narrower than the bandwidth of the first metal electrode layer, The second transparent electrode layer and the second metal electrode layer are in a strip shape, and the bandwidth of the second transparent electrode layer is narrower than the bandwidth of the second metal electrode layer, The resin material in the printing material in which the first metal electrode layer and the second metal electrode layer are formed on the periphery of the first metal electrode layer and the second metal electrode layer is distributed in a biased manner. resin film, A part of the first conductive type semiconductor layer and a part of the second conductive type semiconductor layer between the first metal electrode layer and the second metal electrode layer are covered by the resin film, The first transparent electrode layer and the resin film are arranged in an island shape between the first conductive type semiconductor layer and the resin film and between the second conductive type semiconductor layer and the resin film. The second transparent electrode layer is a transparent conductive film made of the same material. 6. The solar cell according to claim 5, characterized in that, At least one of the two main surfaces of the semiconductor substrate has a concave and convex structure, The valley portion of the first conductive type semiconductor layer and the valley portion of the second conductive type semiconductor layer between the first metal electrode layer and the second metal electrode layer are covered by the resin film, The top of the first conductive type semiconductor layer and the top of the second conductive type semiconductor layer between the first metal electrode layer and the second metal electrode layer are not covered by the resin film and are exposed. 7. The solar cell according to claim 6, characterized in that, Between the valley portion of the first conductive type semiconductor layer and the resin film and between the valley portion of the second conductive type semiconductor layer and the resin film, there are islands arranged in an island shape with the first conductive type semiconductor layer. The transparent electrode layer and the second transparent electrode layer are made of the same transparent conductive film. 8. The solar cell according to any one of claims 5 to 7, characterized in that, The printing material is metal paste, The resin film is formed by exudation of the resin material contained in the printing material. 9. The solar cell according to claim 8, characterized in that, The first metal electrode layer and the second metal electrode layer include silver as a metal material contained in the printing material. 10. The solar cell according to claim 8, characterized in that, The first metal electrode layer and the second metal electrode layer include granular metal materials contained in the printing material. 11. The solar cell according to claim 8, characterized in that, The first metal electrode layer and the second metal electrode layer formed of the printing material have urethane bonds. 12. The solar cell according to any one of claims 5 to 7, characterized in that: The contact area between the first metal electrode layer and the first conductive type semiconductor layer is less than half of the contact area between the first transparent electrode layer and the first conductive type semiconductor layer, The contact area between the second metal electrode layer and the second conductive type semiconductor layer is less than half of the contact area between the second transparent electrode layer and the second conductive type semiconductor layer. 13. A solar cell module, characterized in that, The solar cell according to any one of claims 5 to 12 is provided.