JP2023121604A - Method for manufacturing solar cell, and solar cell - Google Patents

Abstract

To provide a method for manufacturing a solar cell which can simplify formation of a transparent electrode layer.SOLUTION: A method for manufacturing a solar cell includes: a step of forming conductive semiconductor layers 25 and 35 on a rear face side of a substrate 11; a step of forming a transparent conductive film on the conductive semiconductor layers 25 and 35; a step of forming metal electrode layers 29 and 39 on the conductive semiconductor layers 25 and 35; and a step of patterning the transparent conductive film, and forming transparent electrode layers 28 and 38, in this order. The metal electrode layer formation step prints and cures a printing material, and forms a resin film 40 where a resin material is unevenly distributed on a circumference of the metal electrode layers 29 and 39, in the metal electrode layers 29 and 39, a ratio of a metal material contained in the printing material of upper layer metal electrode layers 29u and 39u is higher than that of lower layer metal electrode layers 29l and 39l, and the transparent electrode layer formation step uses a resin film 40 of the metal electrode layer 29 and its circumference, and a resin film 40 of the metal electrode layer 39 and its circumference as masks, and patterns the transparent conductive film.SELECTED DRAWING: Figure 3

Description

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

As solar cells using semiconductor substrates, there are double-sided electrode solar cells in which electrodes are formed on both the light-receiving 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, electrodes are formed on the light-receiving surface side, and sunlight is shielded by these electrodes. On the other hand, in the back electrode type solar cell, no electrode is formed on the light receiving surface side, so the solar cell has a higher light receiving rate than the double electrode type solar cell. Patent Literature 1 discloses a back electrode type solar cell.

The solar cell described in Patent Document 1 includes a semiconductor substrate, a first conductivity type semiconductor layer and a first electrode layer which are sequentially laminated on the back surface side of the semiconductor substrate, and another part of the semiconductor substrate which is sequentially laminated on the back surface side. and a second conductivity type semiconductor layer and a second electrode layer. The first electrode layer and the second electrode layer are separated from each other to prevent short circuits.

JP 2013-131586 A

Generally, each of the first electrode layer and the second electrode layer includes a transparent electrode layer and a metal electrode layer. The metal electrode layer can be separated and formed relatively easily by, for example, a screen printing method using silver paste. On the other hand, the transparent electrode layer must be formed separately by, for example, photolithography using a mask, and the formation process is relatively complicated.

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

A method for manufacturing a solar cell according to the present invention corresponds to a semiconductor substrate, a first conductivity type semiconductor layer and a second conductivity type semiconductor layer arranged on one main surface side of the semiconductor substrate, and a first conductivity type semiconductor layer. A method for manufacturing a back electrode type solar cell comprising a first transparent electrode layer and a first metal electrode layer, and a second transparent electrode layer and a second metal electrode layer corresponding to a second conductivity type semiconductor layer, the method comprising: a semiconductor layer forming step of forming a first conductivity type semiconductor layer on a portion of one main surface of a substrate and forming a second conductivity type semiconductor layer on another portion of the one main surface of the semiconductor substrate; a transparent conductive film forming step of forming a transparent conductive film over and over the conductive semiconductor layer and the second conductive semiconductor layer; A lower metal electrode layer and an upper metal electrode layer are sequentially formed as electrode layers, and a lower metal electrode layer and an upper metal electrode layer are sequentially formed as a second metal electrode layer on the second conductivity type semiconductor layer via a transparent conductive film. and a transparent electrode layer forming step of forming a first transparent electrode layer and a second transparent electrode layer separated from each other by patterning the transparent conductive film, in this order. In the electrode layer forming step, a first metal electrode layer and a second metal electrode layer are formed by printing and curing a printing material containing a particulate metal material, a resin material, and a solvent. A resin film in which a resin material is unevenly distributed is formed on the peripheral edge and the peripheral edge of the second metal electrode layer, and in the first metal electrode layer and the second metal electrode layer, the upper metal electrode layer is applied to the entire printing material of the upper metal electrode layer. The proportion of the metal material contained in the printing material is higher than the proportion of the metal material contained in the printing material of the lower metal electrode layer with respect to the entire printing material of the lower metal electrode layer. and its peripheral resin film, and the second metal electrode layer and its peripheral resin film are used as masks to pattern the transparent conductive film.

A solar cell according to the present invention comprises a semiconductor substrate, a first conductivity type semiconductor layer and a second conductivity type semiconductor layer disposed on one main surface side of the semiconductor substrate, and a first transparent semiconductor layer corresponding to the first conductivity type semiconductor layer. A back electrode type solar cell comprising an electrode layer and a first metal electrode layer, and a second transparent electrode layer and a second metal electrode layer corresponding to a semiconductor layer of a second conductivity type, wherein the first transparent electrode layer and the second metal electrode layer The first metal electrode layer is strip-shaped, the strip width of the first transparent electrode layer is narrower than the strip width of the first metal electrode layer, the second transparent electrode layer and the second metal electrode layer are strip-shaped, and the second transparent electrode layer is strip-shaped. The band width of the layer is narrower than the band width of the second metal electrode layer. A resin film is formed in which a resin material is unevenly distributed, and each of the first metal electrode layer and the second metal electrode layer has a two-layer structure of a lower metal electrode layer and an upper metal electrode layer. The ratio of the metal material contained in the upper metal electrode layer to the entire layer is higher than the ratio of the metal material contained in the lower metal electrode layer to the entire lower metal electrode layer.

According to the present invention, it is possible to simplify the formation of the transparent electrode layer of the solar cell.

It is a side view which shows an example of the solar cell module which concerns on this embodiment. It is the figure which looked at the solar cell which concerns on this embodiment from the back surface side. FIG. 3 is a cross-sectional view taken along line III-III in the solar cell of FIG. 2; It is a figure which shows the semiconductor layer formation process in the manufacturing method of the solar cell which concerns on this embodiment. It is a figure which shows the transparent conductive film formation process in the manufacturing method of the solar cell which concerns on this embodiment. It is a figure which shows the metal electrode layer formation process in the manufacturing method of the solar cell which concerns on this embodiment. It is a figure which shows the transparent electrode layer formation process in the manufacturing method of the solar cell which concerns on this embodiment. It is the result of observing the metal electrode layer on the back surface side of the solar cell of the verification example and the space between the metal electrode layers using an SEM at a magnification of 100 times. It is the result of having observed the part A between the metal electrode layers in FIG. 5A by 450 times magnification using SEM. It is the result of having observed the part B between the metal electrode layers in FIG. 5B by 5000 times magnification using SEM. It is the result of observing the metal electrode layer before and after etching on the back side of the solar cell of the verification example. It is the result of observing the metal electrode layer before and after etching on the back side of the solar cell of the verification example.

An example of an embodiment of the present invention will be described below with reference to the accompanying drawings. In each drawing, the same reference numerals are given to the same or corresponding parts. Also, for convenience, hatching, member numbers, etc. may be omitted, but in such cases, other drawings shall be referred to.

(solar cell module)
FIG. 1 is a side view showing an example of a solar cell module according to this embodiment. A solar cell module 100 includes a plurality of solar cells 1 arranged two-dimensionally.

Solar cells 1 are connected in series and/or in parallel by wiring members 2 . Specifically, the wiring member 2 is connected to a busbar portion (described later) in the electrode layer of the solar cell 1 via a conductive adhesive member. The wiring member 2 is, for example, a known interconnector such as a tab. As the conductive adhesive member, a conductive film such as a resin film containing metal fine particles, a conductive paste containing metal fine particles, a solder paste containing solder particles, or the like is used. Among these, solder paste is preferable from the viewpoint of adhesiveness and low contact resistance.

Solar cell 1 and wiring member 2 are sandwiched between light-receiving surface protective member 3 and back surface protective member 4 . A liquid or solid sealing material 5 is filled between the light-receiving surface protection member 3 and the back surface protection member 4 , thereby sealing the solar cells 1 and the wiring member 2 . The light-receiving surface protection member 3 is, for example, a glass substrate, and the rear surface protection member 4 is a glass substrate or a metal plate. The sealing material 5 is, for example, transparent resin.
The solar cell (hereinafter referred to as solar cell) 1 will be described in detail below.

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

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

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

The finger portions 7f and the finger portions 8f are band-shaped extending in the second direction (Y direction) and are alternately provided in the first direction (X direction).
The first conductivity type region 7 and the second conductivity type region 8 may be formed in stripes.

3 is a cross-sectional view taken along line III-III in the solar cell of FIG. 2. FIG. As shown in FIG. 3 , solar cell 1 includes passivation layer 13 laminated on the light receiving surface side, which is the main surface on the light receiving side of the main surface of semiconductor substrate 11 . In addition, the solar cell 1 is laminated in order on a part (mainly, the first conductivity type region 7) of the back side, which is the main surface (one main surface) of the main surface of the semiconductor substrate 11 opposite to the light receiving surface. a passivation layer 23 , a first conductivity type semiconductor layer 25 and a 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, which are laminated in order on another part (mainly, the second conductivity type region 8) of the back surface side of the semiconductor substrate 11. A layer 37 is provided.

Semiconductor substrate 11 is formed of a crystalline silicon material such as monocrystalline silicon or polycrystalline silicon. The semiconductor substrate 11 is, for example, an n-type semiconductor substrate in which a crystalline silicon material is doped with an n-type dopant. The semiconductor substrate 11 may be, for example, a p-type semiconductor substrate in which a crystalline silicon material is doped with a p-type dopant. Examples of n-type dopants include phosphorus (P). Examples of p-type dopants 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 photocarriers (electrons and holes).

Since crystalline silicon is used as the material of the semiconductor substrate 11, dark current is relatively small, and relatively high output (stable output regardless of illuminance) can be obtained even when the intensity of incident light is low.

The semiconductor substrate 11 may have a pyramid-shaped fine uneven structure called a texture structure on the back surface side. As a result, the efficiency of collecting the light that has passed through the semiconductor substrate 11 without being absorbed increases.

Further, the semiconductor substrate 11 may have a pyramid-shaped fine uneven structure called a texture structure on the light receiving surface side. As a result, the reflection of incident light on the light receiving surface is reduced, and the light confinement effect in the semiconductor substrate 11 is improved.

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 conductivity type region 7 on the back side of the semiconductor substrate 11 . The passivation layer 33 is formed in the second conductivity type region 8 on the back side of the semiconductor substrate 11 . The passivation layers 13, 23, 33 are made of intrinsic (i-type) amorphous silicon material, for example. The passivation layers 13 , 23 , 33 suppress recombination of carriers generated in the semiconductor substrate 11 and increase carrier recovery efficiency.

An antireflection layer made of a material such as SiO, SiN, or SiON may 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 conductivity type semiconductor layer 25 is made of, for example, an amorphous silicon material. The first conductivity type semiconductor layer 25 is a p-type semiconductor layer in which, for example, an amorphous silicon material is doped with a p-type dopant (for example, boron (B) described above).

The second conductivity type semiconductor layer 35 is formed on the passivation layer 33 , that is, in the second conductivity type region 8 on the back side of the semiconductor substrate 11 . The second conductivity type semiconductor layer 35 is made of, for example, an amorphous silicon material. The second conductivity type semiconductor layer 35 is an n-type semiconductor layer in which an n-type dopant (for example, phosphorus (P) described above) is doped in an amorphous silicon material, for example.
The first conductivity type semiconductor layer 25 may be an n-type semiconductor layer, and the second conductivity type semiconductor layer 35 may be a p-type semiconductor layer.

The first-conductivity-type semiconductor layer 25 and the passivation layer 23, and the second-conductivity-type semiconductor layer 35 and the passivation layer 33 form a belt-like shape extending in the second direction (Y-direction). ) are arranged alternately. A portion of the second conductivity type semiconductor layer 35 and the passivation layer 33 may overlap a portion of the adjacent first conductivity type semiconductor layer 25 and the passivation layer 23 (not shown).

The first electrode layer 27 is formed on the first conductivity type semiconductor layer 25 in the first conductivity type region 7 on the back surface side of the semiconductor substrate 11 , corresponding to the first conductivity type semiconductor layer 25 . there is The second electrode layer 37 is formed on the second conductivity type semiconductor layer 35 in the second conductivity type region 8 on the back side of the semiconductor substrate 11 , corresponding to the second conductivity type semiconductor layer 35 . there is The first electrode layer 27 has a first transparent electrode layer 28 and a first metal electrode layer 29 that are sequentially laminated on the first conductivity type semiconductor layer 25 . The second electrode layer 37 has a second transparent electrode layer 38 and a second metal electrode layer 39 that are sequentially laminated on the second conductivity type semiconductor layer 35 .

The first metal electrode layer 29 has a two-layer structure of a lower metal electrode layer 29l and an upper metal electrode layer 29u, and the second metal electrode layer 39 has a two-layer structure of a lower metal electrode layer 39l and an upper metal electrode layer 39u. Structure.

The first transparent electrode layer 28 and the second transparent electrode layer 38 are made of a transparent conductive material. Examples of transparent conductive materials 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, that is, the lower metal electrode layers 29l, 39l and the upper metal electrode layers 29u, 39u are made of particulate metal materials such as silver, copper, aluminum, etc., and insulating resins. It is formed of a conductive paste material containing material and solvent.

The ratio of the metal material contained in the upper metal electrode layer 29u to the entire upper metal electrode layer 29u is higher than the ratio of the metal material contained in the lower metal electrode layer 29l to the entire lower metal electrode layer 29l. In other words, the ratio of the resin material contained in the upper metal electrode layer 29u to the entire upper metal electrode layer 29u is smaller than the ratio of the resin material contained in the lower metal electrode layer 29l to the entire lower metal electrode layer 29l. For example, the weight ratio of the metal material contained in the upper metal electrode layer 29u is 85% or more and 95% or less with respect to the entire upper metal electrode layer 29u.

On the other hand, the ratio of the metal material contained in the lower metal electrode layer 29l to the entire lower metal electrode layer 29l is smaller than the ratio of the metal material contained in the upper metal electrode layer 29u to the entire upper metal electrode layer 29u. In other words, the ratio of the resin material contained in the lower metal electrode layer 29l to the entire lower metal electrode layer 29l is higher than the ratio of the resin material contained in the upper metal electrode layer 29u to the entire upper metal electrode layer 29u. For example, the ratio of the metal material contained in the lower metal electrode layer 29l is 78% or more and less than 88% as a weight ratio with respect to the entire lower metal electrode layer 29l.

Similarly, the ratio of the metal material contained in the upper metal electrode layer 39u to the entire upper metal electrode layer 39u is higher than the ratio of the metal material contained in the lower metal electrode layer 39l to the entire lower metal electrode layer 39l. In other words, the ratio of the resin material contained in the upper metal electrode layer 39u to the entire upper metal electrode layer 39u is smaller than the ratio of the resin material contained in the lower metal electrode layer 39l to the entire lower metal electrode layer 39l. For example, the weight ratio of the metal material contained in the upper metal electrode layer 39u is 85% or more and 95% or less with respect to the entire upper metal electrode layer 39u.

On the other hand, the ratio of the metal material contained in the lower metal electrode layer 39l to the entire lower metal electrode layer 39l is smaller than the ratio of the metal material contained in the upper metal electrode layer 39u to the entire upper metal electrode layer 39u. In other words, the ratio of the resin material contained in the lower metal electrode layer 39l to the entire lower metal electrode layer 39l is higher than the ratio of the resin material contained in the upper metal electrode layer 39u to the entire upper metal electrode layer 39u. For example, the ratio of the metal material contained in the lower metal electrode layer 39l is 78% or more and less than 88% as a weight ratio with respect to the entire lower metal electrode layer 29l.

The first electrode layers 27 and the second electrode layers 37 are strip-shaped extending in the second direction (Y direction) and are alternately arranged in the first direction (X direction). That is, the first transparent electrode layers 28 and the second transparent electrode layers 38 are band-shaped extending in the second direction (Y direction) and are alternately arranged in the first direction (X direction). The first metal electrode layers 29 and the second metal electrode layers 39 are strip-shaped extending in the second direction (Y direction) 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 band width of the first transparent electrode layer 28 in the first direction (X direction) is narrower than the band width of the first metal electrode layer 29 in the first direction (X direction), and the band width of the second transparent electrode layer 38 in the first direction The band width in the (X direction) is narrower than the band width in the first direction (X direction) of the second metal electrode layer 39 .

Resin in which the insulating resin material in the conductive paste material of the first metal electrode layer 29 and the second metal electrode layer 39 is unevenly distributed on the periphery of the first metal electrode layer 29 and the periphery of the second metal electrode layer 39 A film 40 is formed (details will be described later).

A portion of the first conductivity type semiconductor layer 25 and a portion of the second conductivity type semiconductor layer 35 between the first metal electrode layer 29 and the second metal electrode layer 39 are covered with a resin film 40 . More specifically, the valleys of the uneven structure (texture structure) of the first conductivity type semiconductor layer 25 and the uneven structure of the second conductivity 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, between the first metal electrode layer 29 and the second metal electrode layer 39, the top of the uneven structure of the first conductivity type semiconductor layer 25 and the top of the uneven structure of the second conductivity type semiconductor layer 35 are covered with the resin film 40. not covered with, exposed.

Between the first-conductivity-type semiconductor layer 25 and the resin film 40 and between the second-conductivity-type semiconductor layer 35 and the resin film 40, transparent electrodes made of the same material as the first transparent electrode layer 28 and the second transparent electrode layer 38 are provided. A conductive film 48 is arranged in an island shape (non-continuously). More specifically, a transparent conductive film is placed between the resin film 40 and the valleys of the uneven structure of the first conductivity type semiconductor layer 25 and between the valleys of the uneven structure of the second conductivity type semiconductor layer 35 and the resin film 40 . A film 48 is arranged in an island shape.

The contact area between the first metal electrode layer 29 and the first conductivity type semiconductor layer 25 is less than half the contact area between the first transparent electrode layer 28 and the first conductivity type semiconductor layer 25, and the second metal electrode layer 39 and the second conductivity type semiconductor layer 35 is less than half the contact area between the second transparent electrode layer 38 and the second conductivity type semiconductor layer 35 .

Next, a method for manufacturing a solar cell according to this embodiment will be described with reference to FIGS. 4A to 4D. FIG. 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 layer forming step in the solar cell manufacturing method according to this embodiment. . FIG. 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. be. 4A to 4D show the back side of the semiconductor substrate 11, and the front side of the semiconductor substrate 11 is omitted.

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

For example, after forming a passivation film and a first conductivity type semiconductor film on the entire back surface side of the semiconductor substrate 11 using a CVD method or a PVD method, a mask or a metal mask generated using a photolithographic technique is used. The passivation layer 23 and the first conductivity type semiconductor layer 25 may be patterned using an etching method. Etching solutions for the p-type semiconductor film include, for example, hydrofluoric acid containing ozone and acidic solutions such as a mixed solution of nitric acid and hydrofluoric acid. Alkaline solutions such as aqueous potassium solution may be mentioned.

Alternatively, the passivation layer 23 and the p-type semiconductor layer 25 are formed using a mask when laminating the passivation layer and the first conductivity type semiconductor layer on the back surface side of the semiconductor substrate 11 using the CVD method or the PVD method. and patterning may be performed simultaneously.

Next, a passivation layer 33 and a second-conductivity-type semiconductor layer 35 are formed on another portion of the back surface side of the semiconductor substrate 11, specifically, on the second-conductivity-type region 8 (semiconductor layer forming step).

For example, in the same manner as described above, after forming a passivation film and a second conductivity type semiconductor film on the entire back surface side of the semiconductor substrate 11 by using the CVD method or the PVD method, a mask or a metal layer generated by using a photolithography technique is used. The passivation layer 33 and the second conductivity type semiconductor layer 35 may be patterned using an etching method using a mask.

Alternatively, when stacking the passivation layer and the second conductivity type semiconductor layer on the back surface side of the semiconductor substrate 11 using the CVD method or the PVD method, the passivation layer 33 and the second conductivity type semiconductor layer 35 are formed using a mask. Film formation and patterning may be performed simultaneously.

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

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

Next, as shown in FIG. 4C, the first metal electrode layer 29 is formed on the first conductivity type semiconductor layer 25 via the transparent conductive film 28Z, and the second conductivity type semiconductor layer 35 is formed via the transparent conductive film 28Z. A second metal electrode layer 39 is formed thereon. That is, the lower metal electrode layer 29l and the upper metal electrode layer 29u are sequentially formed on the first conductivity type semiconductor layer 25 with the transparent conductive film 28Z interposed therebetween. Further, a lower metal electrode layer 39l and an upper metal electrode layer 39u are formed in order on the second conductivity type semiconductor layer 35 via the transparent conductive film 28Z (metal electrode layer forming step).

The first metal electrode layer 29 and the second metal electrode layer 39, that is, the lower metal electrode layers 29l, 39l and the upper metal electrode layers 29u, 39u are formed by printing a printing material (eg, ink). Methods for forming the first metal electrode layer 29 and the second metal electrode layer 39, that is, methods for forming the lower metal electrode layers 29l and 39l and the upper metal electrode layers 29u and 39u include screen printing, inkjet, and gravure coating. method, dispenser method, or the like. Among these, the screen printing method is preferable.

The printing material contains particulate (for example, spherical) metal material in an insulating resin material. The printing material may contain a solvent or the like for adjusting viscosity or coatability.

Matrix resin etc. are mentioned as an insulating resin material. More specifically, the insulating resin is preferably a polymer compound, particularly preferably a thermosetting resin or an ultraviolet curable resin, and representative examples thereof include epoxy, urethane, polyester, and silicone resins.

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

The ratio of the metal material contained in the printed material of the upper metal electrode layer 29u to the total printed material of the upper metal electrode layer 29u is the ratio of the printed material of the lower metal electrode layer 29l to the total printed material of the lower metal electrode layer 29l. greater than the proportion of metallic materials. In other words, the ratio of the resin material contained in the printing material of the upper metal electrode layer 29u to the entire printing material of the upper metal electrode layer 29u is the same as the printing material of the lower metal electrode layer 29l to the entire printing material of the lower metal electrode layer 29l. less than the proportion of the resin material contained in the For example, the weight ratio of the metal material contained in the printing material of the upper metal electrode layer 29u is 85% or more and 95% or less with respect to the entire printing material.

On the other hand, the ratio of the metal material contained in the printed material of the lower metal electrode layer 29l to the entire printed material of the lower metal electrode layer 29l is less than the percentage of metal material used. In other words, the ratio of the resin material contained in the printing material of the lower metal electrode layer 29l to the entire printing material of the lower metal electrode layer 29l is the same as the printing material of the upper metal electrode layer 29u to the entire printing material of the upper metal electrode layer 29u. greater than the proportion of printing material contained in the For example, the ratio of the metal material contained in the printing material of the lower metal electrode layer 29l is 78% or more and less than 88% as a weight ratio with respect to the entire printing material.

Similarly, the ratio of the metal material contained in the printing material of the upper metal electrode layer 39u to the entire printing material of the upper metal electrode layer 39u is greater than the percentage of metal material contained. In other words, the ratio of the resin material contained in the printing material of the upper metal electrode layer 39u to the entire printing material of the upper metal electrode layer 39u is the same as the printing material of the lower metal electrode layer 39l to the entire printing material of the lower metal electrode layer 39l. less than the proportion of the resin material contained in the For example, the weight ratio of the metal material contained in the printing material of the upper metal electrode layer 39u is 85% or more and 95% or less with respect to the entire printing material.

On the other hand, the ratio of the metal material contained in the printed material of the lower metal electrode layer 39l to the entire printed material of the lower metal electrode layer 39l is less than the percentage of metal material used. In other words, the ratio of the resin material contained in the printing material of the lower metal electrode layer 39l to the entire printing material of the lower metal electrode layer 39l is the printing material of the upper metal electrode layer 39u to the entire printing material of the upper metal electrode layer 39u. greater than the proportion of printing material contained in the For example, the ratio of the metal material contained in the printing material of the lower metal electrode layer 39l is 78% or more and less than 88% as a weight ratio with respect to the entire printing material.

Next, after printing the first metal electrode layer 29 and the second metal electrode layer 39, 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. That is, after printing the lower metal electrode layers 29l, 39l and the upper metal electrode layers 29u, 39u, the insulating resin in the lower metal electrode layers 29l, 39l and the upper metal electrode layers 29u, 39u is cured. 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 the periphery of the first metal electrode layer 29 and the periphery of the second metal electrode layer 39 are coated with the insulating resin material. A resin film 40 is formed in which the material is unevenly distributed.

At this time, the valleys of the uneven structure (texture structure) of the transparent conductive film 28</b>Z 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 with the resin film 40 and is exposed.

It should be noted that the first metal electrode layer 29 and the second metal electrode layer 39 formed of conductive paste in this manner may have urethane bonds. For example, compared to epoxy resin, urethane resin shrinks less during cross-linking, and cracks are less likely to occur in the resin. If cracks are less likely to occur in the resin, it is possible to prevent the etching solution from penetrating into the metal electrode layer. It can prevent deterioration.

Next, as shown in FIG. 4D, etching is performed 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. By patterning the transparent conductive film 28Z, the first transparent electrode layer 28 and the second transparent electrode layer 38 separated from each other are formed (transparent electrode layer forming step). An etching method includes, for example, a wet etching method, and an etching solution includes an acidic solution such as hydrochloric acid (HCl).

At this time, between the first metal electrode layer 29 and the second metal electrode layer 39, the etching of the transparent conductive film 28Z proceeds from the top to the valley of the uneven structure (texture structure). Here, in order to separate the first transparent electrode layer 28 and the second transparent electrode layer 38, it is sufficient that the transparent conductive film therebetween is not continuous, and the transparent conductive film 48 is formed in the valleys of the uneven structure. They may remain in the form of islands. When the transparent conductive film 48 remains in the form of islands in the valleys of the uneven structure, the resin film 40 in the valleys of the uneven structure remains on the first conductivity type semiconductor layer 25 and the second conductivity type semiconductor layer 35 .
Through the above steps, the back electrode type solar cell 1 of the present 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 step, a first transparent electrode layer and a second transparent electrode layer separated from each other are formed by patterning the transparent conductive film using, for example, photolithography. In the photolithography method,
・Apply a resist on the transparent conductive film,
・By exposing the resist to light, an opening is formed in the resist,
forming a first transparent electrode layer and a second transparent electrode layer separated from each other by etching the transparent conductive film exposed in the opening using the resist as a mask;
・Remove the resist.

In contrast, according to the solar cell manufacturing method of the present embodiment, the metal electrode layer forming step and the transparent electrode layer forming step are included in this order after the transparent conductive film forming step. Using the first metal electrode layer 29 and the second metal electrode layer 39 formed in the electrode layer forming step as masks, the transparent conductive film 28Z is patterned to form the first transparent electrode layer 28 and the second metal electrode layer 28 separated from each other. A transparent electrode layer 38 is formed. As a result, according to the method for manufacturing a solar cell of the present embodiment, it is not necessary to use a photolithography method using a mask as in the conventional method, and the formation of the transparent electrode layer can be simplified and shortened. . As a result, the cost of solar cells and solar cell modules can be reduced.

Here, if the transparent conductive film 28Z is patterned using the first metal electrode layer 29 and the second metal electrode layer 39 as a mask, the first metal electrode layer 29 and the second metal electrode are formed when the transparent conductive film 28Z is etched. The transparent conductive film 28Z under the layer 39 is also etched, and there is a possibility that the first transparent electrode layer 28 and the first metal electrode layer 29 and the second transparent electrode layer 38 and the second metal electrode layer 39 are peeled off. be.

In this regard, according to the method for manufacturing a solar cell of the present embodiment, in the metal electrode layer forming step, a printing material containing a particulate metal material, a resin material, and a solvent is printed and cured to form the first metal. A resin film 40 in which a resin material is unevenly distributed is formed on the periphery of the electrode layer 29 and the periphery of the second metal electrode layer 39, and in the transparent electrode layer forming step, the first metal electrode layer 29 and the resin film 40 on the periphery thereof are formed. Then, using the second metal electrode layer 39 and its peripheral resin film 40 as a mask, the transparent conductive film 28Z is patterned. As a result, the etching of the transparent conductive film 28Z under the first metal electrode layer 29 and the second metal electrode layer 39 is suppressed, the first transparent electrode layer 28 and the first metal electrode layer 29 are peeled off, and the second transparent conductive film 28Z is removed. Delamination of the electrode layer 38 and the second metal electrode layer 39 is suppressed.

In the solar cell 1 manufactured by such a manufacturing method, the band width of the first transparent electrode layer 28 is narrower than the band width of the first metal electrode layer 29, and the band width of the second transparent electrode layer 38 is the second metal. The resin material in the printing material of the first metal electrode layer 29 and the second metal electrode layer 39 is narrower than the band width of the electrode layer 39 and is formed on the periphery of the first metal electrode layer 29 and the periphery of the second metal electrode layer 39 . An unevenly distributed resin film is formed.
In a solar cell manufactured by a conventional solar cell manufacturing method, the band width of the transparent electrode layer is generally wider than the band width of the metal electrode layer.

In addition, in the solar cell 1 manufactured by the manufacturing method of the present embodiment, a portion of the first conductivity type semiconductor layer 25 and the second conductivity type semiconductor layer between the first metal electrode layer 29 and the second metal electrode layer 39 A portion of the layer 35 is covered with a resin film 40 . More specifically, the valleys of the uneven structure (texture structure) of the first conductivity type semiconductor layer 25 and the uneven structure of the second conductivity 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 .

The same material as the first transparent electrode layer 28 and the second transparent electrode layer 38 is placed between the first conductivity type semiconductor layer 25 and the resin film 40 and between the second conductivity type semiconductor layer 35 and the resin film 40 . of transparent conductive films 48 are arranged in an island shape (non-continuously). More specifically, a transparent conductive film is placed between the resin film 40 and the valleys of the uneven structure of the first conductivity type semiconductor layer 25 and between the valleys of the uneven structure of the second conductivity type semiconductor layer 35 and the resin film 40 . A film 48 is arranged in an island shape. As a result, the exposed area of the semiconductor layer 25 of the first conductivity type and the semiconductor layer 35 of the second conductivity type is reduced. Therefore, deterioration of the solar cell and the solar cell module is suppressed, and the reliability (for example, long-term durability) of the solar cell and the solar cell module is improved.

Below, the effect mentioned above is verified.
(Verification example 1)
A passivation layer 23, a first conductivity type semiconductor layer 25, a passivation layer 33, a second conductivity type semiconductor layer 35, and a transparent conductive film 28Z are formed on the back side of a semiconductor substrate 11 having a pyramid-shaped texture structure on the back side. . After that, using a screen printing method using silver paste, the first metal electrode layer 29 (only the lower metal electrode layer 29l) is formed on the first conductivity type semiconductor layer 25 via the transparent conductive film 28Z. , a second metal electrode layer 39 (only the lower metal electrode layer 39l) was formed on the second conductive type semiconductor layer 35 via the transparent conductive film 28Z. After that, 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 seeps out to the periphery of the first metal electrode layer 29 and the periphery of the second metal electrode layer 39, and the periphery of the first metal electrode layer 29 and the periphery of the second metal electrode layer 39 A resin film 40 was formed on the substrate.

The back side of the solar cell manufactured as described above before patterning of the transparent conductive film was observed using an SEM (Field Emission Scanning Electron Microscope S4800, manufactured by Hitachi High-Technologies Corporation). The results are shown in FIGS. 5A-5C. 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 verification example at a magnification of 100 times using an SEM, and FIG. 5B is the portion A between the metal electrode layers in FIG. was observed with a SEM at a magnification of 450 times. FIG. 5C is the result of observing the portion B between the metal electrode layers in FIG. 5B at a magnification of 5000 using SEM.

According to FIGS. 5A to 5C, a resin film 40 (black portion) is formed by unevenly distributing an insulating resin material on the periphery of the first metal electrode layer 29 and the periphery of the second metal electrode layer 39. was confirmed. Further, it is confirmed that the valleys 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). was done. On the other hand, it was 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 was not covered with the resin film 40 and was exposed. As a result, it is expected that the etching of the transparent conductive film 28Z proceeds from the top to the bottom of the concave-convex structure in the subsequent etching in the transparent electrode layer forming step.

Next, using the metal electrode layer as a mask, the back side of the solar cell in which the transparent conductive film is patterned is observed using an SEM. And it was confirmed that the second metal electrode layer 39 was not peeled off. Moreover, it was confirmed that the resin film 40 remained without peeling off in the valleys of the uneven structure between the first metal electrode layer 29 and the second metal electrode layer 39 . Furthermore, a short circuit check between the electrodes was performed to confirm that there was no short circuit between the electrode layers. Since the resin film 40 is not peeled off and there is no short circuit between the electrode layers, the uneven structure of the second conductivity type semiconductor layer 35 and the valleys of the uneven structure of the first conductivity type semiconductor layer 25 and the interlayer between the resin film 40 and the uneven structure of the second conductivity type semiconductor layer 35 It is expected that the island-like transparent conductive film 48 remains between the resin film 40 and the troughs of the resin film 40 to hold the resin film 40 .

By the way, when patterning a transparent electrode layer using a metal electrode layer as a mask, the printing material (for example, metal paste) forming the metal electrode layer is required to have the following properties.
(1) The property of preventing the etching solution (e.g., hydrochloric acid) from penetrating into the printing material (e.g., metal paste) (that is, the protective function that protects the transparent conductive film under the printing material)
(2) Low resistance as an electrode, adhesion to wiring members and conductive adhesive members, and low contact resistance (for example, solderability to wiring members)

The inventor(s) of the present application are
(1) If a large amount of resin material is contained in the printing material of the metal electrode layer, it is possible to make it difficult for the etching solution to permeate the printing material,
(2) If the metal material contained in the printing material of the metal electrode layer is large, the resistance of the metal electrode layer is reduced, and the adhesion to the wiring member and the conductive adhesive member and the contact resistance are reduced (for example, the wiring member (improved solderability with
I have gained the knowledge that

In this respect, according to the solar cell manufacturing method of the present embodiment, the first metal electrode layer 29 is formed with a two-layer structure of the lower metal electrode layer 29l and the upper metal electrode layer 29u. Then, the ratio of the metal material contained in the printed material of the lower metal electrode layer 29l to the entire printed material of the lower metal electrode layer 29l is contained in the printed material of the upper metal electrode layer 29u relative to the entire printed material of the upper metal electrode layer 29u. Make it less than the proportion of metal materials. In other words, the ratio of the resin material contained in the printing material of the lower metal electrode layer 29l to the entire printing material of the lower metal electrode layer 29l is the printing material of the upper metal electrode layer 29u to the entire printing material of the upper metal electrode layer 29u. It is made larger than the ratio of the contained resin material.

Also, the second metal electrode layer 39 is formed with a two-layer structure of a lower metal electrode layer 39l and an upper metal electrode layer 39u. Then, the ratio of the metal material contained in the printed material of the lower metal electrode layer 39l to the entire printed material of the lower metal electrode layer 39l is contained in the printed material of the upper metal electrode layer 39u relative to the entire printed material of the upper metal electrode layer 39u. Make it less than the proportion of metal materials. In other words, the ratio of the resin material contained in the printing material of the lower metal electrode layer 39l to the entire printing material of the lower metal electrode layer 39l is the ratio of the printing material of the upper metal electrode layer 39u to the entire printing material of the upper metal electrode layer 39u. It is made larger than the ratio of the contained resin material.

As a result, the lower metal electrode layers 29 l and 39 l obtain a property that makes it difficult for the etching solution to permeate the printing material, and obtain a protective function to protect the transparent conductive film under the metal electrode layers 29 and 39 .

On the other hand, the ratio of the metal material contained in the upper metal electrode layer 29u to the entire upper metal electrode layer 29u is set higher than the ratio of the metal material contained in the lower metal electrode layer 29l to the entire lower metal electrode layer 29l.

Also, the ratio of the metal material contained in the upper metal electrode layer 39u to the entire upper metal electrode layer 39u is made higher than the ratio of the metal material contained in the lower metal electrode layer 39l to the entire lower metal electrode layer 39l.

As a result, the upper metal electrode layers 29u and 39u are reduced in resistance of the metal electrode layers 29 and 39, high adhesion to the wiring members and conductive adhesive members, and low contact resistance (for example, soldering to the wiring members). (improved attachability) can be realized. As a result, a solar cell having high photoelectric conversion efficiency characteristics can be obtained.

Below, the effect mentioned above is verified.
(Verification example 2)
As in Verification Example 1, using a screen printing method using silver paste, only the lower metal electrode layer 29l (the silver content of the printing material is 84 [ %]) was formed, and only the lower metal electrode layer 39l (the silver content of the printing material was 84 [% by weight]) was formed on the second conductivity type semiconductor layer 35 via the transparent conductive film 28Z. After that, the lower metal electrode layer 29l and the lower metal electrode layer 39l were heat-treated in an oven at 180°C for 1 hour. As a result, the insulating resin material in the printing material exudes to the periphery of the lower metal electrode layer 29l and the periphery of the lower metal electrode layer 39l, and the resin film 40 is formed on the periphery of the lower metal electrode layer 29l and the periphery of the lower metal electrode layer 39l. was formed.

Next, the transparent conductive film 28Z is patterned by etching using the lower metal electrode layer 29l and its peripheral resin film 40, and the lower metal electrode layer 39l and its peripheral resin film 40 as masks. , a first transparent electrode layer 28 and a second transparent electrode layer 38 separated from each other were formed. A hydrochloric acid (HCl) undiluted solution was used as an etching solution, and the immersion time in the hydrochloric acid undiluted solution was 45 seconds.

(Verification example 3)
As in Verification Example 1, using a screen printing method using silver paste, only the upper metal electrode layer 29u (the silver content of the printing material is 91 [ %]) was formed, and only the upper metal electrode layer 39u (the silver content of the printing material was 91 [% by weight]) was formed on the second conductivity type semiconductor layer 35 via the transparent conductive film 28Z. After that, the upper metal electrode layer 29u and the upper metal electrode layer 39u were heat-treated in an oven at 180° C. for 1 hour. As a result, the insulating resin material in the printing material exudes to the periphery of the upper metal electrode layer 29u and the periphery of the upper metal electrode layer 39u, and the resin film 40 is formed on the periphery of the upper metal electrode layer 29u and the periphery of the upper metal electrode layer 39u. was formed.

Next, the transparent conductive film 28Z is patterned by etching using the upper metal electrode layer 29u and its peripheral resin film 40, and the upper metal electrode layer 39u and its peripheral resin film 40 as masks. , a first transparent electrode layer 28 and a second transparent electrode layer 38 separated from each other were formed. A hydrochloric acid (HCl) undiluted solution (hydrogen chloride concentration: 36% by weight) was used as the etching solution, and the immersion time in the hydrochloric acid undiluted solution was 45 seconds.

Observation results of the back side of the solar cell of Verification Example 2 before etching of the transparent conductive film produced as described above (left side) and the back side of the solar cell of Verification Example 2 after etching of the transparent conductive film. The observed results (right side) are shown in FIG. 6A. Also, the result of observing the back side of the solar cell of Verification Example 3 before etching the transparent conductive film (left side) and the result of observing the back side of the solar cell of Verification Example 3 after etching the transparent conductive film (right side). is shown in FIG. 6B. 6A and 6B are the results of observing the metal electrode layer on the back side of the solar cell of the verification example at a magnification of 100 using a laser microscope (LEXT OLS4100 manufactured by Olympus).

According to FIG. 6A, even if the lower metal electrode layer 29l (or the lower metal electrode layer 39l) of Verification Example 2 (the silver content of the printing material is 84 [% by weight]) is immersed in the hydrochloric acid undiluted solution for 45 seconds, the metal electrode layer is It remained unpeeled. This prevents the undiluted hydrochloric acid from penetrating into the lower metal electrode layer 29l (or the lower metal electrode layer 39l) and prevents the transparent conductive film under the lower metal electrode layer 29l (or the lower metal electrode layer 39l) from being etched. This is presumed to be due to

On the other hand, according to FIG. 6B, when the upper metal electrode layer 29u (or the upper metal electrode layer 39u) of Verification Example 3 (the silver content of the printing material is 91 [% by weight]) was immersed in a hydrochloric acid undiluted solution for 45 seconds, the metal electrode layer peeled off. This is because the hydrochloric acid undiluted solution penetrated into the upper metal electrode layer 29u (or the upper metal electrode layer 39u), and the transparent conductive film under the upper metal electrode layer 29u (or the upper metal electrode layer 39u) was etched. guessed.

The upper electrode layer 29u (or the upper metal electrode layer 39u) of Verification Example 3 (the silver content of the printing material is 91 [% by weight]) is the same as the lower metal electrode layer 29l (or the lower metal electrode layer 39l) of Verification Example 2. (A silver content of 84 [weight %] in the printing material), and it was confirmed that the solderability with wiring members, for example, is improved.

Although the embodiments of the present invention have been described above, 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, the heterojunction solar cell 1 is exemplified as shown in FIG. Applicable to solar cells.

Moreover, in the above-described embodiments, a solar cell having a crystalline silicon substrate was exemplified, but the present invention is not limited to this. For example, a solar cell may have a gallium arsenide (GaAs) substrate.

REFERENCE SIGNS LIST 1 solar cell 2 wiring member 3 light receiving surface protection member 4 back surface protection member 5 sealing material 7 first conductivity type region 8 second conductivity type region 7b, 8b busbar portion 7f, 8f finger portion 11 semiconductor substrate 13, 23, 33 passivation Layer 25 First conductivity type semiconductor layer 27 First electrode layer 28 First transparent electrode layer 28Z Transparent conductive film 29 First metal electrode layer 29l Lower metal electrode layer 29u Upper metal electrode layer 35 Second conductivity type semiconductor layer 37 Second electrode layer 38 second transparent electrode layer 39 second metal electrode layer 39l lower metal electrode layer 39u upper metal electrode layer 40 resin film 48 transparent conductive film 100 solar cell module

Claims (16)

A semiconductor substrate, a first conductivity type semiconductor layer and a second conductivity type semiconductor layer arranged on one main surface side of the semiconductor substrate, a first transparent electrode layer and a first metal corresponding to the first conductivity type semiconductor layer A method for manufacturing a back electrode type solar cell comprising an electrode layer, and a second transparent electrode layer and a second metal electrode layer corresponding to the second conductivity type semiconductor layer, the method comprising:
A semiconductor in which the first conductivity type semiconductor layer is formed on a part of the one main surface side of the semiconductor substrate, and the second conductivity type semiconductor layer is formed on another part of the one main surface side of the semiconductor substrate. a layer forming step;
a transparent conductive film forming step of forming a transparent conductive film over and over the first conductive semiconductor layer and the second conductive semiconductor layer;
A lower metal electrode layer and an upper metal electrode layer are sequentially formed as the first metal electrode layer on the first conductivity type semiconductor layer with the transparent conductive film interposed therebetween, and the second conductive layer is formed with the transparent conductive film interposed therebetween. a metal electrode layer forming step of sequentially forming a lower metal electrode layer and an upper metal electrode layer as the second metal electrode layer on the mold semiconductor layer;
a transparent electrode layer forming step of forming the first transparent electrode layer and the second transparent electrode layer separated from each other by patterning the transparent conductive film;
in that order,
In the metal electrode layer forming step,
The first metal electrode layer and the second metal electrode layer are formed by printing and curing a printing material containing a particulate metal material, a resin material and a solvent, and the periphery of the first metal electrode layer and the forming a resin film in which the resin material is unevenly distributed around the periphery of the second metal electrode layer;
In the first metal electrode layer and the second metal electrode layer, the ratio of the metal material contained in the printing material of the upper metal electrode layer to the entire printing material of the upper metal electrode layer is the lower metal electrode layer. more than the ratio of the metal material contained in the printing material of the lower metal electrode layer to the entire printing material of
In the transparent electrode layer forming step, the transparent conductive film is patterned using the first metal electrode layer and its peripheral resin film and the second metal electrode layer and its peripheral resin film as masks. ,
A method for manufacturing a solar cell. 2. The method of manufacturing a solar cell according to claim 1, wherein the weight ratio of said metal material contained in said printing material of said upper metal electrode layer is 85% or more and 95% or less with respect to said whole printing material. 3. The method of manufacturing a solar cell according to claim 1, wherein in said transparent electrode layer forming step, said transparent conductive film is patterned by a wet etching method using an etching solution. 4. The method of manufacturing a solar cell according to claim 1, wherein in said metal electrode layer forming step, said printing material is printed using a screen printing method. A semiconductor substrate, a first conductivity type semiconductor layer and a second conductivity type semiconductor layer arranged on one main surface side of the semiconductor substrate, a first transparent electrode layer and a first metal corresponding to the first conductivity type semiconductor layer A back electrode type solar cell comprising an electrode layer, and a second transparent electrode layer and a second metal electrode layer corresponding to the second conductivity type semiconductor layer,
the first transparent electrode layer and the first metal electrode layer are strip-shaped, the strip width of the first transparent electrode layer is narrower than the strip width of the first metal electrode layer;
the second transparent electrode layer and the second metal electrode layer are strip-shaped, the strip width of the second transparent electrode layer is narrower than the strip width of the second metal electrode layer;
A resin film in which the resin material in the printing material of the first metal electrode layer and the second metal electrode layer is unevenly distributed is formed on the periphery of the first metal electrode layer and the periphery of the second metal electrode layer. cage,
each of the first metal electrode layer and the second metal electrode layer has a two-layer structure of a lower metal electrode layer and an upper metal electrode layer;
The ratio of the metal material contained in the upper metal electrode layer to the entire upper metal electrode layer is higher than the ratio of the metal material contained in the lower metal electrode layer to the entire lower metal electrode layer,
solar cell. A portion of the semiconductor layer of the first conductivity type and a portion of the semiconductor layer of the second conductivity type between the first metal electrode layer and the second metal electrode layer are covered with the resin film. Item 6. The solar cell according to item 5. Between the first conductivity type semiconductor layer and the resin film and between the second conductivity type semiconductor layer and the resin film, transparent electrodes made of the same material as the first transparent electrode layer and the second transparent electrode layer are provided. 7. The solar cell according to claim 6, wherein the conductive film is arranged in islands. At least one main surface side of the two main surfaces of the semiconductor substrate has an uneven structure,
a valley portion of the semiconductor layer of the first conductivity type and a valley portion of the semiconductor layer of the second conductivity type between the first metal electrode layer and the second metal electrode layer are covered with the resin film;
The top portion of the first conductivity type semiconductor layer and the top portion of the second conductivity type semiconductor layer between the first metal electrode layer and the second metal electrode layer are not covered with the resin film and are exposed. ing,
The solar cell according to claim 6 or 7. Between the valley portion of the semiconductor layer of the first conductivity type and the resin film and between the valley portion of the semiconductor layer of the second conductivity type and the resin film, the first transparent electrode layer and the second transparent electrode are provided. 9. The solar cell according to claim 8, wherein the transparent conductive film made of the same material as the layer is arranged in islands. The printing material is a metal paste,
The resin film is formed by exuding a resin material contained in the printing material,
The solar cell according to any one of claims 5-9. 11. The solar cell according to claim 10, wherein said first metal electrode layer and said second metal electrode layer contain silver, which is a metal material contained in said printing material. 12. The solar cell according to claim 10, wherein said first metal electrode layer and said second metal electrode layer contain particulate metal material contained in said printing material. The solar cell according to any one of claims 10 to 12, wherein said first metal electrode layer and said second metal electrode layer formed from said printing material have urethane bonds. a contact area between the first metal electrode layer and the first conductivity type semiconductor layer is half or less than a contact area between the first transparent electrode layer and the first conductivity type semiconductor layer;
The contact area between the second metal electrode layer and the second conductivity type semiconductor layer is half or less than the contact area between the second transparent electrode layer and the second conductivity type semiconductor layer.
The solar cell according to any one of claims 5-13. In the first metal electrode layer and the second metal electrode layer, the ratio of the particulate metal material contained in the printing material of the upper metal electrode layer to the entire printing material of the upper metal electrode layer is the lower metal electrode layer. 15. The solar cell according to any one of claims 5 to 14, wherein the proportion of the particulate metal material contained in the printed material of the lower metal electrode layer relative to the entire printed material of the electrode layer is higher. 16. The solar cell according to claim 15, wherein the weight ratio of said metal material contained in said printing material of said upper metal electrode layer is 85% or more and 95% or less with respect to said whole printing material.

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