KR101680389B1

KR101680389B1 - Solar cell

Info

Publication number: KR101680389B1
Application number: KR1020110022814A
Authority: KR
Inventors: 신명준; 이성은; 권태영; 정주화; 양영성
Original assignee: 엘지전자 주식회사
Priority date: 2011-03-15
Filing date: 2011-03-15
Publication date: 2016-11-28
Also published as: KR20120105168A

Abstract

The present invention relates to a solar cell. One example of the solar cell includes a substrate having a plurality of via holes, an emitter section located on the first surface of the substrate and having a first sheet resistance value, a second sheet resistance value smaller than the first sheet resistance value, A first electrode located on a second surface of the substrate opposite to the first surface of the substrate and connected to the semiconductor electrode through the plurality of via holes, a second electrode on the second surface of the substrate, A second electrode disposed on the second surface and separated from the first electrode and connected to the substrate; and a first conductive connection portion located on the second surface and connected to the first electrode, And the first electrode overlap each other. As a result, the amount of charge moving to the first electrode is increased by the semiconductor electrode having a lower sheet resistance value than that of the emitter portion, thereby improving the efficiency of the solar cell.

Description

Solar cell {SOLAR CELL}

The present invention relates to a solar cell.

Recently, as energy resources such as oil and coal are expected to be depleted, interest in alternative energy to replace them is increasing, and solar cells that produce electric energy from solar energy are attracting attention.

Typical solar cells have a semiconductor portion that forms a p-n junction by different conductive types, such as p-type and n-type, and electrodes connected to semiconductor portions of different conductivity types, respectively.

When light is incident on the solar cell, a plurality of electrons and holes are generated in the semiconductor portion, and the generated electrons and holes are moved in the corresponding direction, that is, electrons move toward the n-type semiconductor portion by the pn junction, As shown in FIG. The transferred electrons and holes are collected by different electrodes connected to the n-type semiconductor portion and the p-type semiconductor portion, respectively, and electric power is obtained by connecting these electrodes with electric wires.

The technical problem to be solved by the present invention is to improve the efficiency of a solar cell.

A solar cell according to one aspect of the present invention includes a substrate having a plurality of via holes, an emitter section located on a first surface of the substrate and having a first sheet resistance value, and a second sheet resistance section connected to the emitter section, A first electrode located on a second surface of the substrate opposite to the first surface of the substrate and connected to the semiconductor electrode through the plurality of via holes, A second electrode disposed on the second surface and separated from the first electrode and connected to the substrate, and a first conductive connection portion located on the second surface and connected to the first electrode, wherein the plurality of via holes And is formed at a portion where the semiconductor electrode and the first electrode overlap.

The semiconductor electrode may include a first portion and a second portion that are located on the first surface of the substrate and each extend in a first direction and a second direction which are different directions.

The first portion and the second portion may have a plurality of intersection points.

The plurality of via holes are preferably located at the plurality of intersections.

The semiconductor electrode is preferably located further on the side surface of the via hole.

The semiconductor electrode is further located on the second surface of the substrate, and the first electrode is in contact with the semiconductor electrode located on the second surface of the substrate.

The first electrode and the second electrode may extend in a third direction different from the first direction and the second direction.

The solar cell according to the above feature may further include an antireflective portion located on the first surface of the substrate and positioned on the emitter portion and the semiconductor portion.

The reflection preventing part may be made of a transparent conductive material.

The reflection preventing portion may be located inside the plurality of via holes.

The solar cell according to the above feature may further include an electric field portion located on the second surface of the substrate in contact with the second electrode.

The first surface of the substrate may be an incident surface on which light is incident.

The substrate may be made of a semiconductor of a first conductivity type, and the emitter may have a second conductivity type different from the first conductivity type.

It is preferable that the semiconductor electrode has the same conductivity type as the emitter portion.

The first conductive connection part may be made of the same material as the first electrode or may be made of another material.

The solar cell according to the above feature may further include a second conductive connection portion located on the second surface and connected to the second electrode.

The second conductive connection part may be made of the same material as the second electrode or may be made of another material.

According to this feature, since the amount of charge moving to the first electrode is increased by the semiconductor electrode having a lower sheet resistance value than the emitter portion, the efficiency of the solar cell is improved.

1 is a partial perspective view of a solar cell according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the solar cell shown in FIG. 1 taken along line II-II.
FIG. 3 is a schematic plan view of a front part and a rear part of a substrate according to an embodiment of the present invention, wherein (a) is a schematic plan view of a part of a front surface of a substrate according to an embodiment of the present invention, and ) Is a schematic plan view of a portion of a backside of a substrate according to one embodiment of the present invention.
4 is a schematic plan view of the back side of a substrate according to one embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

In the drawings, the thickness is enlarged to clearly represent the layers and regions. Whenever a portion of a layer, film, region, substrate, or the like is referred to as being "on" another portion, it includes the case where there is another portion in the middle as well as the other portion. Conversely, when a part is "directly over" another part, it means that there is no other part in the middle. Further, when a certain portion is formed as "whole" on another portion, it means not only that it is formed on the entire surface of the other portion but also that it is not formed on the edge portion.

A solar cell according to an embodiment of the present invention will now be described with reference to FIGS. 1 to 4. FIG.

1 to 4, a solar cell 11 according to an embodiment of the present invention includes a substrate 110, an incident surface (hereinafter referred to as a front surface) that is a surface of the substrate 110 on which light is incident, A semiconductor electrode 123 connected to the emitter section 121, an emitter section 121 and an antireflection section 130 disposed on the semiconductor electrode 123. The emitter region 121 is formed on the emitter region 121, A plurality of first electrodes 141 connected to the semiconductor electrode 123 and a plurality of first electrodes 141 connected to the surface of the substrate 110 which is opposite to the front surface of the substrate 110 (hereinafter referred to as a "back surface" A plurality of second electrodes 151 connected to the plurality of rear electric fields 172, a plurality of first electrodes 141 connected to the plurality of rear electric fields 172, And a second bus bar 152 connected to the plurality of second electrodes 151. The first bus bar 142 is connected to the first bus bar 152 and the second bus bar 152. The first bus bar 142 is connected to the second bus bar 152,

The substrate 110 is a semiconductor substrate of a first conductivity type, for example, a semiconductor such as silicon of p-type conductivity type. At this time, the semiconductor is a crystalline semiconductor such as polycrystalline silicon or single crystal silicon. The substrate 110 has a plurality of via holes 181 penetrating through the substrate 110.

Impurities of a trivalent element such as boron (B), gallium (Ga), and indium (In) are doped to the substrate 110 when the substrate 110 has a p-type conductivity type. Alternatively, however, the substrate 110 may be of the n-type conductivity type. Impurities of pentavalent elements such as phosphorus (P), arsenic (As), and antimony (Sb) may be doped to the substrate 110 when the substrate 110 has an n-type conductivity type.

1 and 2, in an alternative embodiment, the entire surface of the substrate 110 may be textured through a separate texturing process using dry etching or wet etching to provide a textured surface, Lt; / RTI > In this case, the emitter section 121 and the anti-reflection section 130 located on the front surface of the substrate 110 also have an uneven surface. Further, before the texturing process is performed, when a semiconductor ingot made of silicon or the like is cut to form a solar cell substrate, a saw damage removing process ) Can be performed.

When the front surface of the substrate 110 is textured, the incident area of the substrate 110 increases and the light reflectivity decreases due to a plurality of reflection operations due to the irregularities, so that the amount of light incident on the substrate 110 The efficiency of the solar cell 11 is further improved.

The emitter section 121 is a region doped with a second conductive type, for example, an n-type conductive type impurity opposite to the conductive type of the substrate 110, to the substrate 110, , And is located on the front surface of the substrate 110. Thus, the emitter portion 121 of the second conductivity type forms a p-n junction with the first conductive type portion of the substrate 110.

The semiconductor electrode 123 connected to the emitter section 121 is located on the front surface of the substrate 110 and is formed on the substrate 110 as an area doped with impurities of the second conductivity type, And a pn junction.

3A, the semiconductor electrode 123 includes a first portion 1231 extending in the first direction from the front surface of the substrate 110 and a second portion 1231 extending in the second direction intersecting the first direction And a second portion 1232. Therefore, the first portion 1231 and the second portion 1232 of the semiconductor electrode 123 are connected to each other at the intersections. As shown in Figs. 1 and 3 (a), in this example, a plurality of via holes 181 are located at the intersections of the first portion 1231 and the second portion 1232. 2, the semiconductor electrode 123 is formed on the inner surface of the via hole 181, that is, on the side surface of the via hole 181, and on the back surface of the substrate 110 on which the first electrode 141 is formed . Therefore, the portion of the semiconductor electrode 123 formed on the rear surface of the substrate 110 is connected to the first electrode 141.

Therefore, the semiconductor electrodes 123 are arranged in a lattice form on the front surface of the substrate 110. [ Since the first direction and the second direction are oblique with respect to one of the side surfaces of the substrate 110, for example, parallel to the substrate 110, And extend at a predetermined angle (? 1,? 2) with one side of the substrate 110 without being arranged side by side.

The angle? 1 is an angle formed by the first portion 1231 of the semiconductor electrode 123 extending in the first direction and one side of the substrate 110, and the angle? 2 is an angle between the first portion 1231 of the semiconductor electrode 123 extending in the first direction, Is an angle formed by the second portion 1232 of the electrode 123 and one side of the substrate 110, and these angles? 1 and? 2 are larger than 0 degrees and smaller than 90 degrees. As shown in Fig. 3, these angles? 1 and? 2 have a value of 45 degrees as an example. In FIG. 3, the first direction and the second direction intersect vertically, but may intersect at an angle greater than 0 degrees and less than 90 degrees.

The semiconductor electrode 123 has an impurity doping thickness different from that of the emitter 121.

That is, the impurity doping thickness of the semiconductor electrode 123 is larger than the impurity doping thickness of the emitter section 121. Therefore, since the impurity doping thicknesses of the semiconductor electrode 123 and the emitter section 121 are different from each other, the impurity doping concentration of the semiconductor electrode 123 and the emitter section 121 is also different. Therefore, the impurity doping concentration of the semiconductor electrode 123 is larger than the impurity doping concentration of the emitter section 121.

The thickness d11 of the emitter layer 121 and the thickness d12 of the semiconductor electrode 123 are also different because the impurity doping thicknesses of the semiconductor electrode 123 and the emitter layer 121 are different from each other. For example, as shown in FIGS. 1 and 2, the thickness d11 of the emitter section 121 is smaller than the thickness d12 of the semiconductor electrode 123.

The upper surface of the semiconductor electrode 123 protrudes toward the antireflection portion 130 from the upper surface of the emitter portion 121 so that the upper surface of the emitter portion 121 and the upper surface of the semiconductor electrode 123 are electrically connected to the substrate 110 On the different lines parallel to the back surface of the substrate. Therefore, the entire surface of the substrate 110 on which the emitter layer 121 and the semiconductor electrode 123 are formed has an irregular surface due to a difference in doping dopant between the emitter layer 121 and the semiconductor electrode 123. In this case, when the front surface of the substrate 110 has a textured surface, the first thicknesses d11 existing within the error range due to the height difference of the irregularities of the textured surface are the same, And the second thickness d12 of the size existing within the error range due to the difference between the two thicknesses are considered to be equal to each other. At this time, the upper surface of the emitter portion 121 and the upper surface of the semiconductor electrode 123 are parallel to the back surface of the substrate 110 and are in contact with the antireflection portion 130.

The sheet resistance of the emitter layer 121 and the semiconductor electrode 123 is also different due to the difference in the dopant doping thickness between the emitter layer 121 and the semiconductor electrode 123. Generally, since the sheet resistance value is inversely proportional to the thickness of the impurity doping, the sheet resistance value of the emitter section 121 having a thin impurity doping thickness is larger than the sheet resistance value of the semiconductor electrode 123. For example, the sheet resistance value of the emitter section 121 is about 80? / Sq. To about 150? / Sq. And the sheet resistance value of the semiconductor electrode 123 is about 5? / Sq. To about 30? / Sq. Lt; / RTI >

As shown in FIG. 1 and FIG. 3 (a), a portion of the substrate 110 excluding the semiconductor electrode 123 arranged in a lattice form among the portions 121 and 123 doped with the second conductivity type impurity And the emitter portion 121 surrounded by the semiconductor electrode 123 has a rhombic shape.

The emitter 121 and the semiconductor electrode 123 forming the pn junction with the substrate 110 are electrically connected to each other by the light incident on the substrate 110 by a built-in potential difference due to the pn junction The generated electrons and electrons in the holes move to the n-type and the holes move to the p-type. Therefore, when the substrate 110 is a p-type and the emitter 121 and the semiconductor electrode 123 are n-type, the holes move toward the back surface of the substrate 110 and electrons move toward the emitter 121 and the semiconductor electrode 123 Move.

The emitter portion 121 and the semiconductor electrode 123 form a pn junction with the first conductive portion of the substrate 110 or the substrate 110 and thus the substrate 110 is an n-type conductive type The emitter portion 121 and the semiconductor electrode 123 have a p-type conductivity type. In this case, the electrons move toward the back surface of the substrate 110, and the holes move toward the emitter 121 and the semiconductor electrode 123.

The emitter layer 121 and the semiconductor electrode 123 may be formed by doping an impurity of a pentavalent element into the substrate 110 when the emitter layer 121 and the semiconductor electrode 123 have an n- , And when the p-type conductive type is provided, the impurity of the trivalent element may be doped to the substrate 110.

As described above, when electrons and holes are moved by the pn junction between the first conductive type portion of the substrate 110 and the emitter portion 121 and the semiconductor electrode 123, the emissivity value and the impurity doping concentration are different from each other, The moving direction of the charge and the loss amount of the charge due to the impurity are changed by the terminal portion 121 and the semiconductor electrode 123. [

That is, when the semiconductor device is moved through a portion having a low sheet resistance value rather than a portion having a high sheet resistance value among the impurity portions, that is, the emitter portion 121 and the semiconductor electrode 123, the charge is more easily moved, Also, as the doping concentration of the impurity increases, the conductivity of the portion increases.

Therefore, when the charge (for example, electrons) moves to the emitter section 121 and the semiconductor electrode 123 as in this example, the charge located in the emitter section 121 having a high sheet resistance value has a lower sheet resistance value than itself And moves to the semiconductor electrode 123 located close to the position where the semiconductor device is located. At this time, since the impurity doping concentration of the emitter section 121 is smaller than that of the semiconductor electrode 123, the amount of loss of electric charges due to impurities while moving from the emitter section 121 to the semiconductor electrode 123 is reduced.

The electrons traveling to the emitter section 121 located on the front side of the substrate 110 move toward the adjacent semiconductor electrode 123 having a lower sheet resistance value than the emitter section 121 along the upper surface of the emitter section 121 . Therefore, the semiconductor electrode 123 functions as a semiconductor channel for transferring the electric charge toward the emitter 121.

A plurality of via holes 181 are located at the intersections of the first portion 1231 and the second portion 1232 of the semiconductor electrode 123 and the semiconductor electrodes 123 are also formed on the side surfaces of the plurality of via holes 181. [ Electrons traveling along the first and second portions 1231 and 1232 of the semiconductor electrode 123 are positioned on the rear surface of the substrate 110 through the via hole 181 and connected to the semiconductor electrode 123 And is transmitted to the first electrode 141.

Since charges are transferred to the first electrode 141 along the semiconductor electrode 123 having a lower sheet resistance and a higher conductivity than the emitter layer 121 as described above, The amount increases.

The sheet resistance value of the emitter portion 121 is about 80? / Sq. And about 150? / Sq. The amount of light absorbed by the emitter layer 121 itself is further reduced to increase the amount of light incident on the substrate 110 and further reduce the loss of charges due to impurities.

Further, when the sheet resistance value of the semiconductor electrode 123 is about 5? / Sq. And about 30? / Sq. The amount of light absorbed by the semiconductor electrode 123 itself is reduced so that the amount of light incident on the substrate 110 is reduced, Is increased.

The antireflective part 130 located on the emitter part 121 reduces the reflectivity of light incident on the solar cell 11 and increases the selectivity of a specific wavelength area to increase the efficiency of the solar cell 11. At this time, the antireflection portion 130 is located at least a part of the inside of the via hole 181 and is connected to the first electrode 141 by filling at least a part of the inside of the via hole 181.

The antireflective portion 130 may be made of transparent and hydrogenated silicon nitride (SiNx), hydrogenated silicon oxide (SiOx), hydrogenated silicon nitride oxide (SiNxOy), or the like. The anti-reflection portion 130 may have a refractive index of about 2.0 to 2.1.

When the refractive index of the antireflection unit 130 is 2.0 or more, the amount of light absorbed by the antireflection unit 130 itself is further reduced while the reflectivity of light is reduced. When the refractive index of the antireflection unit 130 is 2.1 or less, The reflectivity of the antireflection portion 130 is further reduced.

In this example, the refractive index (2.0 to 2.1) of the antireflection portion 130 has a value between the refractive index (about 1) of air and the refractive index (about 3.5) of the substrate 110. Accordingly, since the change in the refractive index from the air toward the substrate 110 sequentially increases, the reflectivity of light is further reduced by the change in the refractive index, and the amount of light incident on the substrate 110 is further increased.

The antireflective portion 130 also uses a contained hydrogen (H) to change a defect such as a dangling bond existing on the surface of the substrate 110 and its vicinity to a stable bond, And performs a passivation function to reduce the disappearance of the charges that have moved toward the surface of the substrate 110 due to the defects. Therefore, by the passivation function of the antireflective portion 130, the amount of lost charge due to defects is reduced.

The anti-reflection portion 130 may be made of a transparent conductive film such as a transparent conductive oxide (TCO) in another example. At this time, at least a part of the charges moving toward the emitter 121 and the semiconductor electrode 123 moves to the antireflection unit 130 having a lower sheet resistance value than that of the emitter 121 and the semiconductor electrode 123, And then transferred to the first electrode 141 after moving into the via hole 181. [ Therefore, the amount of charge moving to the first electrode 141 increases as compared with the case where the first electrode 141 moves only along the semiconductor electrode 123.

1 and 2, the antireflective portion 130 has a single-layer structure, but may have a multi-layered structure such as a double-layered structure. When the antireflective portion 130 has a multilayer structure, the antireflective portion 130 may be formed of silicon nitride (SiNx), silicon oxide (SiOx), silicon oxynitride (SiOxNy), aluminum oxide (AlxOy), and titanium oxide (TiOx) Or the like. The antireflection portion 130 may be omitted if necessary.

The plurality of first electrodes 141 located on the rear surface of the substrate 110 are electrically connected to the via hole 181 formed in the substrate 110, that is, the first electrode 141 of the semiconductor electrode 123, as shown in FIG. Extends in parallel to each other along the intersection of the portion 1231 and the second portion 1232, and has a mainly stripe shape. At this time, the first electrode 141 is connected to the antireflection part 130 present in at least a part of the inside of the via hole 181 in contact with.

At this time, as described above, the semiconductor electrode 123 located on the rear surface of the substrate 110 is not only formed around the portion where the via hole 181 is formed in the rear surface of the substrate 110 but also the via hole 181 is formed, The plurality of first electrodes 141 are connected to the semiconductor electrode 123 located on the rear surface of the substrate 110. The first electrode 141 is disposed on the rear surface of the substrate 110,

The plurality of first electrodes 141 contain at least one conductive material such as aluminum (Al).

The plurality of first electrodes 141 are electrically connected to the charge transferred from the front surface of the substrate 110 through the semiconductor electrode 123 which is in contact with the plurality of via holes 181 and the charge of the semiconductor electrode 123 Collects the charge transferred through the photodiode. At this time, since the plurality of first electrodes 141 are connected to the semiconductor electrode 123 having a lower sheet resistance value than the emitter 121, the charge transfer efficiency is improved.

The plurality of first electrodes 141 are spaced apart from each other as shown in FIG. 3 (b) and FIG. 4, and extend in a predetermined direction. At this time, the extending direction of the first electrode 141 extends in a third direction different from the first and second directions, and the third direction is a direction parallel to one side of the substrate 110.

The rear electric field 172 is a region in which impurities of the same conductivity type as the substrate 110 are doped at a higher concentration than the substrate 110, for example, a p + region.

A potential barrier is formed due to the difference in impurity concentration between the first conductive region (for example, p-type) of the substrate 110 and the rear electric field 172, and thus the electric field is directed toward the rear electric field 172 The electron transport is disturbed while the hole transport toward the rear electric field 172 becomes easier. Accordingly, the rear electric field 172 reduces the amount of electric charge lost due to the recombination of electrons and holes at the back surface and the vicinity of the substrate 110, accelerates the movement of a desired electric charge (e.g., a hole) ) In the direction of the arrow.

The plurality of second electrodes 151 are in contact with the rear electric part 172 located on the rear surface of the substrate 110 and spaced apart from the plurality of first electrodes 141 to extend in the extending direction of the plurality of first electrodes 141 In the same direction. Therefore, each second electrode 151 also has a stripe shape. 3, the plurality of second electrodes 151 are spaced apart from each other. On the rear surface of the substrate 110, a first electrode 141 extending long in the same direction, Two electrodes 151 are alternately arranged.

The second electrode 151 is made of the same material as the first electrode 141, and thus contains a conductive material such as aluminum (Al). However, in an alternative example, the first electrode 141 and the second electrode 151 may be made of different materials.

The second electrode 151 collects charge, for example, holes, moving from the rear electric field 172 side.

The second electrode 151 is in contact with the rear electric field portion 172 having an impurity concentration higher than that of the substrate 110 so that the distance between the substrate 110 and the rear electric field portion 172 between the second electrode 151 The contact resistance is reduced and the charge transfer efficiency from the substrate 110 to the second electrode 151 is improved.

The first bus bar 142 connected to the plurality of first electrodes 141 is located at the edge of the rear surface of the substrate 110 and extends in the fourth direction intersecting the plurality of first electrodes 141. Accordingly, the first bus bar 142 functions as a conductive connection portion connecting the plurality of first electrodes 141 to each other. At this time, the first bus bar 142 is parallel to one side of the substrate 110.

The second bus bar 152 connected to the plurality of second electrodes 151 is located at the edge of the rear surface of the substrate 110 so as to face the first bus bar 142 and has a plurality of second electrodes 151, In a fourth direction intersecting with the first direction. The second bus bar 152 also functions as a conductive connection for connecting the plurality of second electrodes 151 to each other. Thus, the second bus bar 152 is also parallel to one side of the substrate 110.

The first and second bus bars 142 and 152 collect electric charges from a plurality of first and second electrodes 141 and 151 respectively connected to the first and second bus bars 142 and 152, Is connected to an external device through an interconnector such as a ribbon containing a conductive material and outputs collected electric charges (e.g., electrons) to an external device.

The first and second bus bars 142 and 152 may be formed of the same material as the first and second electrodes 141 and 151 and may be formed together when the first and second electrodes 141 and 151 are formed. . Accordingly, the first bus bar 142 may be formed integrally with the plurality of first electrodes 141, and the second bus bar 152 may be integrally formed with the plurality of second electrodes 151.

Since the first and second bus bars 142 and 152 collect the electric charges collected by the first and second electrodes 141 and 151 intersecting each other and move the first and second bus bars 142 and 152 in a desired direction, The widths of the first and second electrodes 142 and 152 are larger than the widths of the first and second electrodes 141 and 151, respectively.

The operation of the solar cell 11 according to this embodiment having such a structure is as follows.

When the light is irradiated to the solar cell 11 and is incident on the emitter section 121 and the semiconductor electrode 123 as the semiconductor and the substrate 110 through the reflection preventing section 130, Occurs. At this time, the reflection loss of the light incident on the substrate 110 is reduced by the anti-reflection unit 130, and the amount of light incident on the substrate 110 is increased.

Electrons and holes are moved to the substrate 110 having the p-type conductivity type and the emitter portion 121 having the n-type conductivity type and the semiconductor electrode 123 by the pn junction do.

At this time, the charge moving toward the emitter part 121 moves to the semiconductor electrode 123, moves along the semiconductor electrode 123, passes through the adjacent via hole 181, and the first electrode 141 located on the rear surface of the substrate 110, And the charge moving to the rear surface of the substrate 110 is collected through the rear electric section 172 into the second electrode 151 and moved along the respective first and second bus bars 142 and 152 .

When the first bus bar 142 and the second bus bar 152 are connected to each other by a wire, a current flows and is used as electric power from the outside.

At this time, the charge moving toward the emitter section 121 moves to the semiconductor electrode 123 having a lower sheet resistance value and higher conductivity than the emitter section 121, and then moves to the first electrode 141 along the semiconductor electrode 123 , The amount of charge moving to the first electrode 141 increases.

However, in an alternative example, the first and second bus bars 142 and 152 may be omitted. in this case,

Charges (for example, electrons) collected in the plurality of first electrodes 141 and charges (for example, holes) moved to the plurality of second electrodes 151 are respectively transferred to the corresponding positions in the direction crossing the first electrodes 141 A plurality of second electrodes 151 which are attached to the first electrodes 141 in a direction intersecting with the second electrodes 151 and connected to the plurality of first electrodes 141 to function as conductive connecting parts, And an interconnector attached to the conductive adhesive portion, and is output to an external device. These conductive adhesive portions may be formed of a material different from that of the first and second electrodes 141 and 151.

The conductive adhesive portion may be formed of a conductive adhesive film, a conductive paste, a conductive epoxy, or the like.

The conductive adhesive film may include a resin and conductive particles dispersed in the resin. The resin is not particularly limited as long as it is a material having adhesiveness. However, a thermosetting resin can be used as the resin in order to improve adhesion reliability.

As the thermosetting resin, at least one resin selected from an epoxy resin, a phenoxy resin, an acryl resin, a polyimide resin, and a polycarbonate resin may be used.

The resin may contain, as optional components other than the thermosetting resin, a known curing agent and a curing accelerator.

For example, the resin may be a silane-based coupling agent, a titanate-based coupling agent, an alumina-based coupling agent, or an alumina-based coupling agent to improve adhesion between the first and second electrodes 141 and 151 and the interconnector. An aluminate-based coupling agent, and the like. In order to improve the dispersibility of the conductive particles, a dispersing agent such as calcium phosphate or calcium carbonate may be contained. Further, the resin may contain rubber components such as acrylic rubber, silicone rubber, and urethane in order to control the modulus of elasticity.

The conductive particles are not particularly limited as long as they have conductivity. The conductive particles may be selected from the group consisting of copper (Cu), silver (Ag), gold (Au), iron (Fe), nickel (Ni), lead (Pb), zinc (Zn), cobalt (Co), titanium Mg) as a main component, and may be composed of only metal particles or metal coated resin particles. The conductive adhesive film having such a constitution may further include a release film.

In order to alleviate the compressive stress of the conductive particles and improve the connection reliability, it is preferable to use the metal-coated resin particles as the conductive particles.

In order to improve the dispersibility, the conductive particles preferably have a particle diameter of 2 mu m to 30 mu m.

From the viewpoint of the connection reliability after the resin is cured, the blending amount of the conductive particles dispersed in the resin is preferably 0.5 volume% to 20 volume% with respect to the total volume of the conductive adhesive film. If the blending amount of the conductive particles is less than 0.5% by volume, the physical contact with the front electrode is reduced, and current flow may not be smooth. If the blending amount exceeds 20% by volume, the relative amount of the resin decreases, Can be degraded.

As described above, in the state that the first and second electrodes 141 and 151 and the interconnector are bonded by the conductive adhesive film, the gap between the conductive particles and the first and second electrodes 141 and 151, Or the conductive particles may directly contact at least one of the first and second electrodes 141 and 151 and the interconnector.

Therefore, the charge moved to the first and second electrodes 141 and 151 is jumped to the conductive particles, then jumps to the interconnector, and the charge transferred to the first and second electrodes 141 and 151, respectively, And may be transferred to the interconnector or directly to the interconnector via conductive particles or first and second electrodes 141 and 151. [

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It belongs to the scope of right.

Claims

A first conductive type substrate having a plurality of via holes,
Forming a pn junction with the substrate as a doped region of the substrate of the second conductivity type opposite to the first conductivity type on the first surface of the substrate and having a first surface resistance value Emitter,
Forming a pn junction with the substrate as a region located on a first surface of the substrate and connected to the emitter portion and wherein an impurity of the second conductivity type is doped on a first surface of the substrate, A semiconductor electrode having a smaller second sheet resistance value,
A first electrode located on a second surface of the substrate opposite the first surface of the substrate and connected to the semiconductor electrode through the plurality of via holes,
A second electrode disposed on the second surface of the substrate so as to be separated from the first electrode and connected to the substrate,
/ RTI >
Wherein the plurality of via holes are located at a portion where the semiconductor electrode and the first electrode overlap,
Wherein the first surface of the substrate is an incident surface through which light is incident, and light is incident on the entire first surface.

The method of claim 1,
Wherein the semiconductor electrode has a first portion and a second portion located on the first surface of the substrate and extending in a first direction and a second direction, respectively, which are different directions.

3. The method of claim 2,
Wherein the first portion and the second portion have a plurality of intersection points.

4. The method of claim 3,
And the plurality of via holes are located at the plurality of intersections.

5. The method according to any one of claims 2 to 4,
Wherein the semiconductor electrode is further disposed on a side surface of the via hole.

5. The method according to any one of claims 2 to 4,
Wherein the semiconductor electrode is further located on the second surface of the substrate and the first electrode is in contact with the semiconductor electrode located on the second surface of the substrate.

3. The method of claim 2,
Wherein the first electrode and the second electrode extend in a third direction different from the first direction and the second direction.

The method of claim 1,
And an antireflective portion located on the first surface of the substrate and located on the emitter portion and the semiconductor electrode.

9. The method of claim 8,
Wherein the reflection preventing portion is made of a transparent conductive material.

The method of claim 9,
Wherein the reflection preventing portion is located inside the plurality of via holes.

The method of claim 1,
And an electric field portion located on the second surface of the substrate in contact with the second electrode.

delete

The method of claim 1,
Wherein the substrate is made of a semiconductor of a first conductivity type.

The method of claim 13,
Wherein the emitter portion has a second conductivity type different from the first conductivity type.

The method of claim 14,
Wherein the semiconductor electrode has the same conductivity type as the emitter portion.

The method of claim 1,
Wherein the first conductive connection portion is made of the same material as the first electrode.

The method of claim 1,
And a first conductive connection portion located on the second surface and connected to the first electrode,
Wherein the first conductive connection portion is made of a material different from that of the first electrode.

The method of claim 17,
And a second conductive connection portion located on the second surface and connected to the second electrode.

The method of claim 18,
And the second conductive connection portion is made of the same material as the second electrode.

The method of claim 1,
And a first conductive connection portion located on the second surface and connected to the first electrode,
Wherein the first conductive connection portion is made of a material different from that of the second electrode.