KR20230027628A - Solar cell and method for manufacturing the same - Google Patents

Abstract

A solar cell with excellent efficiency according to the present embodiment comprises: a photoelectric conversion unit including a first photoelectric conversion unit including a photoelectric conversion layer made of a perovskite compound, and a second photoelectric conversion unit including a semiconductor substrate; a bonding layer formed between the first photoelectric conversion unit and the second photoelectric conversion unit; a first electrode electrically connected to the photoelectric conversion unit on one surface of the photoelectric conversion unit; and a second electrode electrically connected to the photoelectric conversion unit on the other surface of the photoelectric conversion unit. The bonding layer includes a first conductive poly layer formed on the second photoelectric conversion unit and a second conductive poly layer formed on the first conductive poly layer. Therefore, efficiency and productivity can be improved by proposing the bonding layer between the first photoelectric conversion unit and the second photoelectric conversion unit to be a multilayer structure of a tunneling layer and a polysilicon layer.

Description

Solar cell and its manufacturing method {SOLAR CELL AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a solar cell and a method for manufacturing the same, and more particularly, to a solar cell having an improved structure and a method for manufacturing the same.

A solar cell including a semiconductor substrate is widely used because of its excellent efficiency. However, there are certain limitations in improving the efficiency of solar cells including semiconductor substrates, so solar cells with various structures capable of improving photoelectric conversion efficiency have been proposed.

For example, a solar cell including a perovskite compound that absorbs light of a short wavelength and performs photoelectric conversion using the short wavelength as a photoelectric conversion unit has been proposed. In a solar cell including such a perovskite compound as a photoelectric conversion unit, as in Korean Patent Publication No. 10-2016-0040925, a photoelectric conversion unit including a perovskite compound and another structure or material composed of another It is common to implement excellent efficiency by stacking photoelectric conversion units.

In a solar cell having such a structure, it is very important that the plurality of photoelectric conversion units stacked on each other have excellent connection characteristics in order to improve efficiency.

To this end, Korean Patent No. 10-2018-0026454 discloses a multi-junction photovoltaic device. In the prior art, a tandem solar cell structure in which a heterojunction structure and a perovskite solar cell are laminated is claimed, and TCO is applied as a junction layer of the two, that is, a recombinant layer.

In such a structure, there is a limitation in structural scalability of the lower cell by applying TCO to nc-SiOx:H and the junction layer based on the heterojunction cell. In addition, by applying TCO as a bonding layer, process suitability with the perovskite layer formed thereon is deteriorated, resulting in a problem in surface coverage. And, in the case of applying TCO as a bonding layer in this way, the TCO conductivity characteristic is excellent compared to nc-Si:H, and thus, a problem in that open-circuit voltage performance is deteriorated due to a shunt path occurs.

Korean Patent Publication No. 10-2016-0040925 (2016.04.15.) Domestic Patent Publication No. 10-2018-0026454 (2018.03.16.)

The present embodiment is intended to provide a solar cell having excellent efficiency and a manufacturing method thereof. In particular, the present embodiment provides a solar cell having excellent efficiency while having a tandem type structure including a photoelectric conversion unit including a perovskite compound and another photoelectric conversion unit having a different material or structure and a manufacturing method thereof want to provide

More specifically, the present embodiment is to provide a solar cell having excellent efficiency by smoothing the movement of carriers while improving the bonding characteristics between two photoelectric conversion units in a tandem structure including a plurality of photoelectric conversion units and a manufacturing method thereof. do.

In addition, this embodiment is intended to provide a solar cell and a manufacturing method thereof that can be manufactured by a simple process and improve productivity.

The solar cell according to the present embodiment includes a photoelectric conversion unit including a first photoelectric conversion unit including a photoelectric conversion layer made of a perovskite compound and a second photoelectric conversion unit including a semiconductor substrate; a bonding layer formed between the first photoelectric conversion unit and the second photoelectric conversion unit; a first electrode electrically connected to the photoelectric conversion unit on one surface of the photoelectric conversion unit; and a second electrode electrically connected to the photoelectric conversion unit on the other surface of the photoelectric conversion unit, wherein the bonding layer includes a first conductivity-type poly layer formed on the second photoelectric conversion unit and the first conductivity-type poly and a second conductive poly layer formed on the layer.

The second photoelectric converter is formed in the semiconductor substrate on one surface of the semiconductor substrate and has a crystal structure different from that of the first semiconductor layer on a first semiconductor layer of a first conductivity type and on the other surface of the semiconductor substrate. The branch may include a second semiconductor layer of a second conductivity type.

The first semiconductor layer is formed in the semiconductor substrate and includes an amorphous portion, and the second semiconductor layer positioned on the rear surface of the semiconductor substrate includes a polycrystalline portion, and a gap between the semiconductor substrate and the second semiconductor layer is formed. A second tunneling layer may be further included.

The junction layer may further include a junction tunneling layer formed between the first conductivity type first semiconductor layer and the first conductivity type poly layer.

A doping concentration of the first conductivity-type first semiconductor layer may be lower than a doping concentration of the first conductivity-type poly layer.

The junction tunneling layer may have a thickness of 3 nm or less.

The semiconductor substrate and the second semiconductor layer may have an insulating junction structure or a tunnel junction structure in which the second intermediate film made of an insulating material is bonded therebetween.

A doping concentration of the second conductive poly layer may be higher than that of the second semiconductor layer.

The junction tunneling layer and the second intermediate layer may include an insulating material.

The junction tunneling layer and the second intermediate layer may include silicon oxide.

the first photoelectric converter is positioned on one surface of the second photoelectric converter, the first electrode is positioned on the first photoelectric converter, and the second electrode is positioned on the second semiconductor layer of the second photoelectric converter; The second semiconductor layer may include a polycrystalline portion, and stack structures of the first electrode and the second electrode may be different from each other.

Meanwhile, the present invention provides a semiconductor substrate, a first semiconductor layer on one surface of the semiconductor substrate, and the second semiconductor layer formed separately from the semiconductor substrate on the other surface of the semiconductor substrate and having a crystal structure different from that of the first semiconductor layer. forming a bonding layer including a second photoelectric converter including forming a bonding layer on the first semiconductor layer and a first conductive poly layer simultaneously doped with the first semiconductor layer; forming a first photoelectric conversion unit including a photoelectric conversion layer made of a perovskite compound on the bonding layer; and forming a first electrode electrically connected to the first photoelectric conversion unit on one side of the first photoelectric conversion unit and a second electrode electrically connected to the second photoelectric conversion unit on the other side of the second photoelectric conversion unit. It provides a method for manufacturing a solar cell comprising a.

The forming of the second photoelectric conversion unit and the bonding layer may include forming an oxide film on both surfaces of the semiconductor substrate; separately forming an intrinsic poly semiconductor layer on the oxide film; forming a first conductivity-type doping layer on the intrinsic poly semiconductor layer positioned on the front surface of the semiconductor substrate, and forming a second conductivity-type doping layer on the intrinsic poly semiconductor layer positioned on the rear surface of the semiconductor substrate; and performing heat treatment to form the intrinsic poly semiconductor layer on the rear surface of the semiconductor substrate as a second conductivity-type second semiconductor layer, and to form the intrinsic poly semiconductor layer on the front surface of the semiconductor substrate as the first conductivity-type poly layer. steps may be included.

In the step of forming the first conductivity type poly layer, the first conductivity type dopant from the first conductivity type dopant is diffused to the entire surface of the semiconductor substrate through the lower oxide film to diffuse to the first conductivity type first semiconductor layer. can be formed simultaneously.

After forming the first conductive poly layer, a hydrogen implantation step of injecting hydrogen into the first conductive poly layer and the second semiconductor layer may be further included.

After the hydrogen implantation step, the bonding layer may be completed by further forming the second conductive poly layer on the first conductive poly layer.

According to the present embodiment, in a tandem type structure including a first photoelectric conversion unit including a perovskite compound and a second photoelectric conversion unit including a semiconductor substrate, between the first photoelectric conversion unit and the second photoelectric conversion unit Efficiency and productivity can be improved by suggesting a multilayer structure of a tunneling layer and a polysilicon layer as the bonding layer. That is, by proposing a multi-layered structure of a tunneling layer and a polysilicon layer as the junction layer, matching with the first photoelectric conversion unit and carrier transfer characteristics can be improved. In addition, by using the structure of the bonding layer to form the front surface of the second photoelectric conversion unit, the structure of the second photoelectric conversion unit can be applied in various ways, and process cost and time can be saved by reducing the number of process windows.

In addition, since a high-concentration polysilicon layer is applied as a bonding layer, leakage current loss due to a defect in the first photoelectric converter due to a conductivity difference is reduced.

In this way, conformity is improved in the lamination of the bonding layer and the first photovoltaic unit, which is advantageous for a large area.

1 is a schematic cross-sectional view of a solar cell according to an embodiment of the present invention.
FIG. 2 is a front plan view showing a front side of the solar cell shown in FIG. 1 .
3 is a diagram schematically illustrating an example of a conductivity type and role of a plurality of layers included in a photoelectric conversion unit of a solar cell according to an embodiment of the present invention.
FIG. 4 is an energy band diagram schematically illustrating energy bands of the solar cell shown in FIG. 3 and a photoelectric conversion unit of the solar cell according to Comparative Example 1. Referring to FIG.
5 is a flowchart of a method of manufacturing a solar cell according to an embodiment of the present invention.
6 is a detailed flow chart up to the formation of the doped layer of FIG. 5 .
7A and 7B are cross-sectional views for explaining the manufacturing method of FIG. 6 .
8 is a detailed flow chart up to hydrogen injection in FIG. 5 .
9A to 9D are cross-sectional views illustrating the manufacturing method of FIG. 8 .
FIG. 10 is a detailed flowchart showing the completion of the bonding layer of FIG. 5 .
11 is a cross-sectional view illustrating the manufacturing method of FIG. 10 .
FIG. 12 is a detailed flow chart of forming the first photoelectric conversion unit and electrodes of FIG. 5 .
13A to 13B are cross-sectional views illustrating the manufacturing method of FIG. 11 .
14 is a schematic cross-sectional view of a solar cell according to another embodiment of the present invention.
15A and 15B show conductivity characteristics showing leakage current reduction of the present invention and Comparative Example 1.
16 illustrates the reflectivity improvement of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, it goes without saying that the present invention is not limited to these embodiments and can be modified in various forms.

In the drawings, in order to clearly and concisely describe the present invention, parts not related to the description are omitted, and the same reference numerals are used for the same or extremely similar parts throughout the specification. In addition, in the drawings, the thickness, width, etc. are enlarged or reduced in order to make the description more clear, and the thickness, width, etc. of the present invention are not limited to those shown in the drawings.

And when a certain part "includes" another part throughout the specification, it does not exclude other parts unless otherwise stated, and may further include other parts. In addition, when a part such as a layer, film, region, plate, etc. is said to be “on” another part, this includes not only the case where it is “directly on” the other part, but also the case where another part is located in the middle. When a part such as a layer, film, region, plate, etc. is said to be "directly on" another part, it means that there are no intervening parts.

Hereinafter, a solar cell and a manufacturing method thereof according to embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this specification, the expression "first" or "second" is only used to distinguish one from the other, but the present invention is not limited thereto.

FIG. 1 is a cross-sectional view schematically illustrating a solar cell according to an exemplary embodiment of the present invention, and FIG. 2 is a front plan view illustrating a front side of the solar cell illustrated in FIG. 1 . For a clear understanding, in FIG. 2 , the first electrode layer of the first electrode is omitted and the second electrode layer is mainly illustrated.

Referring to FIG. 1 , a solar cell 100 according to the present embodiment may include a photoelectric conversion unit 10 including first and second photoelectric conversion units 110 and 120 . That is, the photoelectric conversion unit 10 may have a tandem type structure including a plurality of photoelectric conversion units 110 and 120 stacked on each other. At this time, the bonding layer (tunnel bonding layer) 130 is positioned on one surface (eg, the front surface) of the second photoelectric conversion unit 120 or on the first semiconductor layer 124, and the second photoelectric conversion unit 120 and The first photoelectric converter 110 positioned thereon is electrically connected. In FIG. 1 , the bonding layer 130 has a plurality of layered structures, and is between the first semiconductor layer 124 of the second photoelectric conversion unit 124 and the second transmission layer 116 of the first photoelectric conversion unit 110. However, the present invention is not limited thereto. The bonding layer 130 may have a thin thickness so that tunneling of carriers can occur smoothly.

More specifically, the photoelectric conversion unit 10 includes a first photoelectric conversion unit 110 including a photoelectric conversion layer 112 made of a perovskite compound, a semiconductor substrate (eg, a silicon substrate) 122 It may include a second photoelectric conversion unit 120 including a. At this time, the second photoelectric converter 120 includes a semiconductor substrate 122 and a first semiconductor layer 124 formed separately from the semiconductor substrate 122 on one surface (eg, the front surface) of the semiconductor substrate 122, , The second semiconductor layer 126 formed separately from the semiconductor substrate 10 on the other surface (eg, the rear surface) of the semiconductor substrate 122 may be included. In addition, the solar cell 100 includes a first electrode 42 electrically connected to the photoelectric conversion unit 10 on one surface (eg, the front surface) of the photoelectric conversion unit 10, and the other surface of the photoelectric conversion unit 10 ( For example, a second electrode 44 electrically connected to the photoelectric conversion unit 10 may be included on the rear surface). A more detailed description of this is as follows.

In the present embodiment, the semiconductor substrate 122 in the second photoelectric converter 120 is a crystalline semiconductor (eg, a single crystal or polycrystalline semiconductor, for example, a single crystal or polycrystalline semiconductor) including a single semiconductor material (eg, a Group 4 element). polycrystalline silicon). Then, since the semiconductor substrate 122 is based on the semiconductor substrate 122 having fewer defects due to its high crystallinity, the second photoelectric converter 120 may have excellent electrical characteristics. In particular, the semiconductor substrate 122 may be formed of a single-crystal semiconductor, for example, single-crystal silicon, to have better electrical characteristics. As such, the second photoelectric converter 120 may have a crystalline silicon solar cell structure including the crystalline semiconductor substrate 122 .

The front and/or rear surface of the semiconductor substrate 122 may be textured to have a concavo-convex or anti-reflection structure. The concavo-convex or anti-reflection structure may have, for example, a pyramidal shape in which the surface constituting the front and/or rear surface of the semiconductor substrate 122 is composed of the (111) plane of the semiconductor substrate 122 and has an irregular size. As a result, if the surface roughness is relatively large, the reflectance of light can be reduced. In the drawing, an anti-reflection effect is maximized by forming irregularities or an anti-reflection structure on the front and rear surfaces of the semiconductor substrate 122, respectively. However, the present invention is not limited thereto, and a concavo-convex or anti-reflection structure may be formed on at least one of the front and rear surfaces, or both the front and rear surfaces may not have concavo-convex or anti-reflection structures.

In this embodiment, the semiconductor substrate 122 is doped with a dopant of the first or second conductivity type at a lower doping concentration than that of the first or second semiconductor layers 124 and 126 to form a base region having the first or second conductivity type. can be configured. That is, the semiconductor substrate 122 may include only the base region without including a doped region formed by doping the base region with a dopant additionally.

In this embodiment, the first semiconductor layer 124 located on one surface (eg, the front surface) of the semiconductor substrate 122 may be a semiconductor layer having a first conductivity type including a first conductivity type dopant. Also, the second semiconductor layer 126 located on the other surface (eg, the rear surface) of the semiconductor substrate 122 may be a semiconductor layer having a second conductivity type including a second conductivity type dopant.

For example, as a p-type dopant among the first and second conductivity-type dopants, a Group 3 element such as boron (B), aluminum (Al), gallium (Ga), or indium (In) may be used. Group 5 elements such as phosphorus (P), arsenic (As), bismuth (Bi), and antimony (Sb) may be used as the dopant. The first or second conductivity type dopants of the semiconductor substrate 122 and the first or second conductivity type dopants of the first or second semiconductor layers 124 and 126 may be the same material or different materials.

The role of the first and second semiconductor layers 124 and 126 according to the conductivity type of the semiconductor substrate 122 and the first and second semiconductor layers 124 and 126, and the first photoelectric converter included in the first photoelectric conversion unit 110. Materials and roles of the first and second transmission layers 114 and 116 may be different. This will be described in more detail after the first photoelectric converter 110 and the first and second electrodes 42 and 44 are described.

A second intermediate film 126a may be provided between the rear surface of the semiconductor substrate 122 and the second semiconductor layer 126 . For example, the second intermediate film 126a may be formed in contact with the rear surface of the semiconductor substrate 122 and the second semiconductor layer 126 may be formed in contact with the second intermediate film 126a. According to this, it is possible to simplify the carrier movement path by simplifying the structure, but the present invention is not limited thereto and various modifications are possible.

In this embodiment, the first and second semiconductor layers 124 and 126 and/or the second intermediate film 126a may be entirely formed on the front and rear surfaces of the semiconductor substrate 122, respectively. Accordingly, the first and second semiconductor layers 124 and 126 and/or the second intermediate layer 126a may be formed in a sufficient area without separate patterning. However, the present invention is not limited thereto.

In this embodiment, the first semiconductor layer 124 is formed of the same semiconductor layer as the substrate 122 and may have the same crystal structure, but the second semiconductor layer 126 is separate from the semiconductor substrate 122 or the base region. It may be composed of a semiconductor layer to be formed. Accordingly, the crystal structure of the second semiconductor layer 126 may be different from that of the semiconductor substrate 122 .

A bonding layer (tunnel bonding layer) 130 is positioned on one surface (eg, the front surface) of the second photoelectric conversion unit 120 or on the first semiconductor layer 124 so that the second photoelectric conversion unit 120 and thereon The positioned first photoelectric converter 110 is electrically connected. In FIG. 1 , a plurality of layer structures in which the bonding layer 130 contacts the first semiconductor layer 124 of the second photoelectric conversion unit 120 and the second transmission layer 116 of the first photoelectric conversion unit 110, respectively. It is shown to have.

The bonding layer 130 has a plurality of layered structures having a thin thickness so that tunneling of carriers can occur smoothly, and the thickness of each layer is, for example, the thickness of the first electrode layer 420 of the first electrode 42. It may have a smaller thickness.

The bonding layer 130 may electrically connect the first photoelectric conversion unit 110 and the second photoelectric conversion unit 120, and the light (eg, long-wavelength light) used in the second photoelectric conversion unit 120 may be It may contain a permeable material. The bonding layer 130 has at least three layered structures, including the junction tunneling layer 132 formed on the first semiconductor layer 124, the first conductive poly layer 134 formed on the junction tunneling layer 132, and A second conductive poly layer 136 formed on the first conductive poly layer 134 may be included.

That is, a structure in which n-type and p-type polysilicon layers are alternately stacked is included, and while recombination of carriers is induced and vertical conductivity is low, the influence of a pinhole on the top can be reduced. In addition, light (eg, short-wavelength light) used in the first photoelectric conversion unit 110 is reflected to the first photoelectric conversion unit 110 and used in the second photoelectric conversion unit 120 (eg, light having a short wavelength). Long wavelength light) may be transmitted and provided to the second photoelectric conversion unit 120 .

A first photoelectric conversion unit 110 including a photoelectric conversion layer 112 including a perovskite compound may be positioned on the bonding layer 130 . More specifically, the first photoelectric conversion unit 110 includes the photoelectric conversion layer 112 and the photoelectric conversion layer 112 on the other side opposite to one side of the photoelectric conversion layer 112 adjacent to the second photoelectric conversion unit 120. and the first transport layer (first carrier transport layer) 114 located between the first electrode 42 and the bonding layer on one side of the photoelectric conversion layer 112 adjacent to the second photoelectric conversion unit 120 It may include a second transport layer (second carrier transport layer) 116 positioned between the photoelectric conversion layer 112 and the photoelectric conversion layer 130 .

For example, the photoelectric conversion layer 112 may be a photoactive layer composed of a perovskite compound having a perovskite structure and excited by light to form carriers (electrons and holes). For example, the perovskite structure may have a chemical formula of AMX ₃ (where A is a monovalent organic ammonium cation or metal cation; M is a divalent metal cation; X is a halogen anion). The photoelectric conversion layer 112 is AMX ₃ , CH ₃ NH ₃ PbI ₃ , CH ₃ NH ₃ PbI _x Cl _(3-x) , CH ₃ NH ₃ PbI _x Br _(3-x) , CH ₃ NH ₃ PbCl _x Br _(3-x) , HC(NH ₂ ) ₂ PbI ₃ , HC(NH ₂ ) ₂ PbI _x Cl _(3-x) , HC(NH ₂ ) ₂ PbI _x Br _(3-x) , HC(NH ₂ ) ₂ PbCl _x Br _(3-x) , or a compound in which A of AMX ₃ is partially doped with Cs. However, the present invention is not limited thereto, and various materials may be used as the photoelectric conversion layer 112 .

The second transmission layer 116 positioned between the bonding layer 130 and the photoelectric conversion layer 112 on the other surface (eg, the rear surface) of the photoelectric conversion unit 112 has a bandgap relationship with the photoelectric conversion layer 112. This is a layer that extracts and transmits the second carrier, and is located between the photoelectric conversion layer 112 and the first electrode 42 on one surface (eg, the front surface) of the photoelectric conversion layer 112. The first transmission layer ( 114) is a layer that extracts and transmits the first carriers according to a bandgap relationship with the photoelectric conversion layer 112. Here, the first carrier is a carrier moving to the first semiconductor layer 124 by the first conductivity type of the first semiconductor layer 124 and is a majority carrier of the first conductivity type. If the first semiconductor layer 124 is n-type, the first carrier is an electron, and if the first semiconductor layer 124 is p-type, the first carrier is a hole. And, the second carriers are carriers moving to the second semiconductor layer 126 due to the second conductivity type of the second semiconductor layer 126 and are majority carriers for the second conductivity type. If the second semiconductor layer 126 is p-type, the second carrier is a hole, and if the second semiconductor layer 126 is n-type, the second carrier is an electron.

Among the first and second transport layers 114 and 116, an electron transport layer may be referred to as an electron transport layer, and a hole transport layer may be referred to as a hole transport layer. For example, as the hole transport layer, a spiro-bifluorene compound (eg, 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9'-spirobifluorene ( spiro-OMeTAD), etc.), poly-triarylamine (PTAA), or a metal compound (eg, molybdenum oxide, etc.). Further, the electron transport layer may include fullerene (C ₆₀ ) or a derivative thereof (eg, phenyl-C61-butyric acid methyl ester (PCBM), etc.). However, the present invention is not limited thereto, and various materials that can serve to transfer the first or second carriers to the first transport layer 114 and the second transport layer 116, or the electron transport layer and the hole transport layer may contain substances.

In FIG. 1 , the second transmission layer 116 , the photoelectric conversion layer 112 , and the first transmission layer 114 are in contact with each other to minimize the carrier movement path. However, the present invention is not limited thereto and various modifications are possible.

The first electrode 42 is positioned on the photoelectric conversion unit 10 (for example, the first transmission layer 114 positioned on the front side of the first photoelectric conversion unit 110), and the photoelectric conversion unit 10 (for example, , The second electrode 44 may be positioned on the second semiconductor layer 126 positioned on the rear side of the second photoelectric conversion unit 120 .

In this embodiment, the first electrode 42 may include a first electrode layer 420 and a second electrode layer 422 sequentially stacked on one surface (eg, the front surface) of the photoelectric conversion unit 10 .

Here, the first electrode layer 420 may be entirely formed on the photoelectric conversion unit 10 (eg, the first transmission layer 114 positioned on the front side of the first photoelectric conversion unit 110). For example, the first electrode layer 420 may be entirely formed on the photoelectric conversion unit 10 (eg, the first transmission layer 114 located on the front side of the first photoelectric conversion unit 110) while contacting it. there is. In this specification, "formed entirely" may include not only covering the entirety of the photoelectric conversion unit 10 without an empty space or an empty area, but also a case where a part of the photoelectric converter 10 is inevitably not formed. In this way, when the first electrode layer 420 is entirely formed on the first photoelectric conversion unit 110, the first carrier can easily reach the second electrode layer 422 through the first electrode layer 420, and thus in the horizontal direction. resistance can be reduced.

Since the first electrode layer 420 is entirely formed on the photoelectric conversion unit 10 as described above, the first electrode layer 420 may be made of a material capable of transmitting light (light-transmitting material). That is, the first electrode layer 420 is made of a transparent conductive material so that the carrier can easily move while allowing light to pass through. Accordingly, even if the first electrode layer 420 is entirely formed over the photoelectric conversion unit 10, light transmission is not blocked. For example, the first electrode layer 420 may include a transparent conductive material (eg, a transparent conductive oxide, for example, metal-doped indium oxide, carbon nano tube (CNT), etc.). Metal doping As the indium oxide, tin doped indium oxide (ITO), tungsten-doped indium oxide (IWO), cesium-doped indium oxide (ICO), etc. However, the present invention is not limited thereto, and the first electrode layer 420 may include various other materials.

A second electrode layer 422 may be formed on the first electrode layer 420 . For example, the second electrode layer 422 may be formed in contact with the first electrode layer 422 . The second electrode layer 422 may be made of a material having better electrical conductivity than the first electrode layer 420 . Accordingly, characteristics such as carrier collection efficiency and resistance reduction by the second electrode layer 422 may be further improved. For example, the second electrode layer 422 may be formed of an opaque metal having excellent electrical conductivity or a metal having lower transparency than the first electrode layer 420 .

As described above, since the second electrode layer 422 may block the incidence of light due to its opaqueness or low transparency, it may be partially formed to minimize shading loss and may have a constant pattern. As a result, light can be incident to a portion where the second electrode layer 422 is not formed.

For example, the second electrode layer 422 may include a plurality of finger electrodes 42a spaced apart from each other while having a constant pitch. Although FIG. 2 illustrates that the finger electrodes 42a are parallel to each other and parallel to the main edge of the photoelectric converter 10 (eg, the semiconductor substrate 122), the present invention is not limited thereto. The second electrode layer 422 may include a bus bar electrode 42b formed in a direction crossing the finger electrodes 42a and connecting the finger electrodes 42a. Such a bus electrode 42b may be provided alone or, as shown in FIG. 2 , a plurality of bus electrodes 42b may be provided with a pitch greater than that of the finger electrodes 42a. At this time, the width of the bus bar electrode 42b may be larger than the width of the finger electrode 42a, but the present invention is not limited thereto. Accordingly, the width of the bus bar electrode 42b may be equal to or smaller than that of the finger electrode 42a. However, the present invention is not limited thereto, and the second electrode layer 422 may have various planar shapes.

In this embodiment, the second electrode 44 may have a stacked structure different from that of the first electrode 42 . This may consider the material of the first photoelectric conversion unit 110 and the crystal structure of the second semiconductor layer 126 included in the second photoelectric conversion unit 120 .

For example, in the present embodiment, the second electrode 44 may include a metal electrode layer 442 positioned on the other surface (eg, the rear surface) of the photoelectric conversion unit 10 . For example, the second electrode 44 is composed of a single layer of a metal electrode layer 442 contacting the photoelectric conversion unit 10 (more specifically, the second semiconductor layer 126), and a transparent conductive oxide layer or the like. You may not have more.

The metal electrode layer 442 of the second electrode 42 may be made of a material having better electrical conductivity than the first electrode layer 420 of the first electrode 42 . For example, the metal electrode layer 442 of the second electrode 42 may be formed of an opaque metal having excellent electrical conductivity or a metal having lower transparency than the first electrode layer 420 of the first electrode 42 . As such, the metal electrode layer 442 may be partially formed on the photoelectric conversion unit 10 to have a certain pattern. Accordingly, in the double-sided light-receiving structure, light may be incident to a portion where the metal electrode layer 442 is not formed.

For example, the metal electrode layer 442 may include a plurality of finger electrodes spaced apart from each other with a constant pitch, and may further include a bus bar electrode formed in a direction crossing the finger electrodes to connect the finger electrodes. there is. The finger electrode 42a and the bus bar electrode 42b included in the second electrode layer 422 of the first electrode 42, except that the metal electrode layer 442 is located on the other surface of the photoelectric conversion unit 10. ) can be applied to the finger electrode and the bus bar electrode of the metal electrode layer 442 . At this time, the width and pitch of the finger electrode 42a and the bus bar electrode 42b of the first electrode 42 are the same as or different from the width and pitch of the finger electrode and the bus bar electrode of the second electrode 44. can have a value. The second electrode layer 422 of the first electrode 42 and the metal electrode layer 442 of the second electrode 44 may have the same or different materials, compositions, shapes, or thicknesses.

In this embodiment, among the first and second electrodes 42 and 44 of the solar cell 100, the metal electrode layer 442, which is opaque or includes a metal, has a certain pattern to cover the entire surface of the photoelectric conversion units 110 and 120. It has a bi-facial structure through which light can be incident on the back side. Accordingly, the amount of light used by the solar cell 100 may be increased to contribute to improving the efficiency of the solar cell 100 .

In the above description, it has been exemplified that the second electrode layer 422 of the first electrode 42 and the metal electrode layer 442 of the second electrode 44 each have a pattern and have the same or similar planar shape. However, the second electrode layer 422 of the first electrode 42 and the metal electrode layer 442 of the second electrode 44 may have different planar shapes. For example, when the solar cell 100 has a single-sided light-receiving structure in which light is not incident on the rear side, the second electrode 44 or the metal electrode layer 442 is used to form the photoelectric conversion unit 10 (more specifically, the second electrode 44). It may be entirely formed (contact formation) on the second semiconductor layer 126. In this way, the shape, arrangement, etc. of the second electrode layer 422 of the first electrode 42 and the metal electrode layer 442 of the second electrode 44 can be modified in various ways.

In this embodiment, the second electrode layer 422 or the metal electrode layer 442 may include a printed layer including a metal and a resin. Here, since the second electrode layer 422 is formed in contact with the first electrode layer 420 and an insulating film is not provided on the surface of the second semiconductor layer 126 where the metal electrode layer 442 is located, a fire penetrating the insulating film or the like No fire-through is required. Therefore, in this embodiment, a glass frit composed of a certain metal compound (eg, an oxide containing oxygen, a carbide containing carbon, a sulfide containing sulfur), etc. is not provided, and a metal and resin (binder) are not provided. , a curing agent, additives) can be used to form a printing layer using a low-temperature baking paste.

More specifically, a printed layer may be formed by applying a low-temperature baking paste containing a metal and a resin without a glass frit and curing the paste by heat treatment. Accordingly, the printed layer included in the second electrode layer 422 or the metal electrode layer 442 may have conductivity because a plurality of metal particles are not sintered but contacted and aggregated. For example, by curing the low-temperature firing paste at a temperature lower than the temperature used in the existing low-temperature process (eg, 150° C. or less), a plurality of printed layers included in the second electrode layer 422 or the metal electrode layer 442 are cured. The metal particles of may have a shape in which they are connected while being in contact with each other without being completely necked.

As such, if the second electrode layer 422 or the metal electrode layer 442 includes a printed layer formed using a low-temperature baking paste, the second electrode layer 422 or the metal electrode layer 442 can be formed by a simple process, and the second electrode layer Deterioration of the first photoelectric conversion unit 110 including the perovskite compound may be prevented from occurring in step 422 or the process of forming the metal electrode layer 442 . However, the present invention is not limited thereto. The second electrode layer 422 or the metal electrode layer 442 may further include a separate metal layer other than the printed layer. layers and the like. Various other variations are possible.

The second electrode layer 422 or the metal electrode layer 442 may include various metals. For example, the second electrode layer 422 or the metal electrode layer 442 may include various metals such as silver, copper, gold, and aluminum. In this embodiment, the second electrode layer 422 and the metal electrode layer 442 may have the same material, structure, shape, thickness, etc. or may have different materials, structures, shapes, thickness, etc. For example, the width of the second electrode layer 422 may be smaller than the width of the metal electrode layer 442 , and/or the thickness of the second electrode layer 422 may be larger than the thickness of the metal electrode layer 442 . This is to sufficiently secure specific resistance while reducing shading loss caused by the second electrode layer 4220 located on the front surface, but the present invention is not limited thereto.

As described above, the photoelectric conversion unit 10 according to the present embodiment includes the second photoelectric conversion unit 120 based on a single semiconductor material (eg, silicon) and the first photoelectric conversion unit 110 based on a perovskite compound. It may have a tandem type structure bonded by the bonding layer 130 . At this time, the first photoelectric conversion unit 110 has a larger band gap than the second photoelectric conversion unit 120 . That is, the first photoelectric conversion unit 110 has a relatively large bandgap and absorbs a short wavelength having a relatively small wavelength and uses it to generate photoelectric conversion, and the second photoelectric conversion unit 120 is the first photoelectric conversion unit. It has a bandgap lower than (110) and effectively absorbs long wavelengths having a wavelength greater than that of light used in the first photoelectric conversion unit 110, and photoelectric conversion is performed using this.

More specifically, when light is incident through the front surface of the solar cell 100, the first photoelectric converter 110 absorbs short wavelengths and generates electrons and holes through photoelectric conversion. At this time, the first carrier moves toward the first electrode 42 and is collected, and the second carrier moves toward the second electrode 44 via the first photoelectric conversion unit 110 and the second photoelectric conversion unit 120. are collected When a long wavelength that is not used in the first photoelectric conversion unit 110 and passes through it reaches the second photoelectric conversion unit 120, the second photoelectric conversion unit 120 absorbs it and converts it to the first carrier and the second photoelectric conversion unit 120. Create 2 carriers. At this time, the first carriers move toward the first electrode 42 through the first photoelectric converter 110 and are collected, and the second carriers move toward the second electrode 44 and are collected.

As mentioned above, in the present embodiment, the first semiconductor layer 124 and the second semiconductor layer 126 included in the first photoelectric conversion unit 110 may have different crystal structures. That is, the junction structure formed by the first semiconductor layer 124 on one surface of the second photoelectric conversion unit 120 and the junction formed by the second intermediate film 126a and/or the second semiconductor layer 126 on the other surface. structure is different. Also, the first electrode 42 adjacent to the first photoelectric conversion unit 110 and the second electrode 44 adjacent to the second photoelectric conversion unit 120 may have different stacked structures.

The first semiconductor layer 124 positioned on the entire surface of the semiconductor substrate 122 may include an amorphous portion (eg, an amorphous layer) doped with a first conductivity type dopant. More specifically, in this embodiment, the first semiconductor layer 124 is doped with a first conductivity type dopant and may be formed of amorphous silicon.

For example, the first semiconductor layer 124 may include an amorphous silicon layer doped with a first conductivity type dopant.

For example, when the first semiconductor layer 124 includes an amorphous silicon layer, a characteristic difference with the semiconductor substrate 122 may be minimized by including the same semiconductor material as the semiconductor substrate 122 .

Also, the second semiconductor layer 126 positioned on the rear surface of the semiconductor substrate 122 may include a polycrystalline portion (eg, a polycrystalline layer) doped with a second conductivity type dopant. More specifically, in this embodiment, the second semiconductor layer 126 may include a polycrystalline portion doped with a second conductivity type dopant and hydrogenated (ie, a polycrystalline portion containing hydrogen). To this end, for example, a hydrogen implantation process of implanting hydrogen into the second semiconductor layer 126 may be performed to improve passivation characteristics of the second semiconductor layer 126 .

Here, the term including a polycrystalline portion may include not only having a polycrystalline structure as a whole, but also having a volume ratio of a portion having a polycrystalline structure greater than a volume ratio of a portion having an amorphous structure. For example, in this embodiment, the second semiconductor layer 126 is made of a polycrystalline semiconductor layer having a polycrystalline structure as a whole, and may have excellent photoelectric conversion efficiency and excellent electrical characteristics.

For example, the second semiconductor layer 126 may include a polycrystalline silicon layer doped with a second conductivity type dopant and containing hydrogen. Here, the polycrystalline silicon layer may mean having a polycrystalline portion containing silicon as a main material. For example, the second semiconductor layer 126 may be formed of a polycrystalline silicon layer doped with a second conductivity type dopant, including hydrogen, and having a polycrystalline structure as a whole.

In this way, when the second semiconductor layer 126 is composed of a polycrystalline portion, it can have high carrier mobility, so it can have excellent photoelectric conversion efficiency and excellent electrical characteristics.

The second intermediate film 126a positioned between the second semiconductor layer 126 and the semiconductor substrate 122 may serve as a passivation film for passivating the surface of the semiconductor substrate 122 . Alternatively, the second intermediate film 126a may serve as a dopant control role or a diffusion barrier preventing the second conductivity type dopant of the second semiconductor layer 126 from diffusing excessively into the semiconductor substrate 122. . For example, the second intermediate film 126a acts as a kind of barrier for electrons and holes to prevent minority carriers from passing through, and after being accumulated in a portion adjacent to the second intermediate film 126a, more than a certain number of carriers are accumulated. Only majority carriers having energy can pass through the second intermediate layer 126a. That is, the second intermediate layer 126a may be a type of tunneling layer. At this time, the majority carriers having energy above a certain level can easily pass through the second intermediate layer 126a due to the tunneling effect.

The second intermediate film 126a may include various materials capable of performing the above-described role, and may include, for example, an insulating material. When the second intermediate layer 126a includes an insulating material, carriers can be smoothly transferred to the second semiconductor layer 126 composed of a polycrystalline portion. For example, the second intermediate layer 126a may be formed of an oxide layer, a dielectric layer including silicon, an insulating layer, a nitride oxide layer, a carbonized oxide layer, or the like. For example, when the second intermediate layer 126a is formed of a silicon oxide layer, the second intermediate layer 126a can be easily manufactured and carriers can be smoothly transferred through the second intermediate layer 126a.

As a result, the semiconductor substrate 122, the second semiconductor layer 126, and/or the second intermediate film 126a include the same semiconductor material (eg, silicon), but the second intermediate film 126a composed of an insulating material (ie, silicon). , insulating film) may have an insulation-junction structure or a tunnel-junction structure bonded with an insulating film therebetween. At this time, since the thickness of the second intermediate film 126a is thin, the movement of the carrier may not be hindered.

In this embodiment, the second semiconductor layer 126 located on the rear surface of the semiconductor substrate 122 is composed of a polycrystalline portion that absorbs a relatively large amount of light, and the first semiconductor layer located on the front surface of the semiconductor substrate 122 ( 124) is composed of an amorphous portion that absorbs less light than the second semiconductor layer 126. Accordingly, unwanted light absorption on the entire surface of the semiconductor substrate 122 can be minimized. Also, in the second semiconductor layer 126 located on the rear surface of the semiconductor substrate 122, carrier transfer characteristics, electrical connection characteristics, and the like can be effectively improved.

In addition, the first semiconductor layer 124 positioned adjacent to the first photoelectric conversion unit 110 is composed of an amorphous portion to improve compatibility with the first photoelectric conversion unit 110 including a perovskite compound, thereby forming a carrier movement characteristics can be improved.

The first semiconductor layer 124 may directly contact the first photoelectric conversion layer 110 with the bonding layer 130 therebetween. That is, the bonding layer 130 may be positioned to contact the first semiconductor layer 124 and the first photoelectric conversion layer 110 may be positioned to contact the bonding layer 130 . Then, the structure can be simplified and the movement of the carrier can be made smooth.

In addition, the second semiconductor layer 126 located on the surface opposite to the surface on which the first photoelectric conversion unit 110 is located on the semiconductor substrate 122 includes a polycrystalline portion to effectively improve carrier transfer characteristics, electrical connection characteristics, and the like. can

In this case, the thickness of the second semiconductor layer 126 may be equal to or greater than the thickness of the first semiconductor layer 124 . For example, the thickness of the second semiconductor layer 126 may be greater than that of the first semiconductor layer 124 . This is because even if the second semiconductor layer 126 is located on the back side of the semiconductor substrate 122 and has a relatively large thickness, the degree of obstructing incident light may not be large. Alternatively, the thickness of the first semiconductor layer 124 may be 10 nm or less (eg, 5 nm to 10 nm) and the thickness of the second semiconductor layer 126 may be 10 nm or more (eg, greater than 10 nm or less than 500 nm). This thickness takes into consideration the characteristics of the first semiconductor layer 124 and the second semiconductor layer 126 and the amount of light passing through them, but the present invention is not limited thereto.

Also, the thickness of the second intermediate film 126a may be smaller than that of the second semiconductor layer 126 . According to this, the second carrier can smoothly pass (for example, tunneling) through the second intermediate layer 126a made of an insulating material. The second intermediate layer 126a may have a thickness of 3 nm or less (eg, 1 nm to 3 nm). This thickness is taken into consideration for the role of the second intermediate film 126a, but the present invention is not limited thereto.

Meanwhile, a multilayer structure of the bonding layer 130 may be provided on the first semiconductor layer 124 .

The bonding layer 130 includes a junction tunneling layer 132 formed on the first semiconductor layer 124 , a first conductive poly layer 134 formed on the junction tunneling layer 132 , and a first conductive poly layer 134 . ) may include a second conductive type poly layer 136 formed on it.

It is limited to maximize efficiency in consideration of the material, location, role, etc. of the junction tunneling layer 132, but the present invention is not limited thereto.

The thickness of the junction tunneling layer 132 may also be similar to that of the second intermediate film 126a, and may satisfy 3 nm or less, preferably 2 nm or less.

A first conductive poly layer 134 and a second conductive poly layer 136 are sequentially stacked on the junction tunneling layer 132 .

When the semiconductor substrate 122 is n-type, the first conductive poly layer 134 can maintain a state in which the first semiconductor layer 124 is doped with a higher concentration of n-type dopant than the substrate 122, and The conductive poly layer 134 may be doped with an n-type dopant at a higher concentration than the first semiconductor layer 124 .

In this embodiment, the first conductive poly layer 134 may have a structure containing hydrogen.

For example, the dopant content of the first conductive poly layer 134 may be 1X10 ²⁰ /cm ³ or more (eg, 8X10 ²¹ /cm ³ or less), and the dopant content of the second semiconductor layer 126 8X10 ²⁰ / cm ³ or less (eg, 1X10 ¹⁹ / cm ³ or more) may be.

Meanwhile, a second conductive poly layer 136 may be formed on the first conductive poly layer 134 .

The second conductive poly layer 136 may be formed of a polysilicon layer doped with a dopant of a different conductivity type from that of the first conductive poly layer 134 .

In this case, when the first conductive poly layer 134 is doped with an n-type dopant, the second conductive poly layer 136 may be doped with a p-type dopant.

The crystallinity of the second conductive poly layer 136 may be less than or equal to that of the first conductive poly layer 134, and the thicknesses of the first conductive poly layer 134 and the second conductive poly layer 136 may be the same. The sum of may be formed to satisfy 200 nm or less.

Meanwhile, the second conductivity type poly layer 136 may be replaced with a nanocrystal layer doped with the second conductivity type, but is not limited thereto.

As such, since the bonding layer is formed in a structure in which n-type and p-type polysilicon layers are alternately stacked on the junction tunneling layer 132, recombination of carriers is induced in each polysilicon layer and vertical conductivity is low, so that the top The influence of the pinhole may be small.

The junction tunneling layer 132 located between the first semiconductor layer 124 and the first conductivity-type poly layer 134 includes a semiconductor material so that the first semiconductor layer 124 and the first conductivity-type poly layer 134 It is possible to improve the electrical connection characteristics of. For example, since the junction tunneling layer 132 includes intrinsic amorphous silicon, recombination on the surface of the first semiconductor layer 124 is effectively prevented by minimizing lattice mismatch with the first semiconductor layer 124. Thus, passivation characteristics can be improved.

Accordingly, the first conductive poly layer 134 and the first semiconductor layer 124 include the same semiconductor material (eg, silicon) with the junction tunneling layer 132 interposed therebetween, but have different crystal structures. It may have a hetero-junction structure.

As mentioned above, the first and second semiconductor layers 124 and 126, the first and second transmission layers ( 114, 116) may have different roles and materials. In consideration of this, the structure of the solar cell 100 according to an example of the present embodiment will be described with reference to FIG. 3 , and carrier movement characteristics accordingly will be described with reference to FIG. 4 .

FIG. 3 is a diagram schematically illustrating an example of a conductivity type and role of a plurality of layers included in the photoelectric conversion unit 10 of the solar cell 100 according to an embodiment of the present invention. For a clear understanding, FIG. 3 mainly shows the stacking order, conductivity type, and role of the plurality of layers included in the photoelectric conversion unit 10 without specifically showing the concavo-convex or anti-reflection structure.

Referring to FIG. 3 , in this example, the semiconductor substrate 122 may have an n-type. When the semiconductor substrate 122 has an n-type, bulk characteristics are excellent and the life time of the carrier can be improved.

And, in this embodiment, the first semiconductor layer 124 may have the same conductivity as the semiconductor substrate 122, n-type, but may have a higher doping concentration than the semiconductor substrate 122, and the second semiconductor layer 126 may have a semiconductor substrate 122. It may have a p-type conductivity different from that of the substrate 122 . Accordingly, the second semiconductor layer 126 located on the rear surface of the semiconductor substrate 122 constitutes an emitter region forming a pn junction with the semiconductor substrate 122, and the first semiconductor layer 124 located on the front surface A front surface field may be formed to prevent recombination by forming a front surface field. Then, since the emitter region directly involved in photoelectric conversion is located on the rear surface, the emitter region can be formed with a sufficient thickness (eg, thicker than the front electric field region) to improve photoelectric conversion efficiency. In addition, light loss may be minimized by forming the first semiconductor layer 124, which is a front electric field region, thinly.

In this case, in the first photoelectric conversion unit 110 located above the second photoelectric conversion unit 120, the first transport layer 114 located on the upper side is composed of an electron transport layer that transfers electrons, and the first transport layer 114 located on the lower side The second transport layer 116 may be configured as a hole transport layer that transports holes. In this case, the first photoelectric converter 110 may have an excellent effect.

In such a solar cell 100, when light is incident through the front surface of the solar cell 100, the first photoelectric converter 110 absorbs short wavelengths and generates electrons and holes through photoelectric conversion. At this time, electrons move toward the first electrode 42 through the first transmission layer 114 and are collected, and holes pass through the second transmission layer 116 and the second photoelectric conversion unit 120 to the second electrode 44. ) and collected. When a long wavelength that is not used in the first photoelectric conversion unit 110 and passes through it reaches the second photoelectric conversion unit 120, the second photoelectric conversion unit 120 absorbs it and generates electrons and holes through photoelectric conversion. do. At this time, electrons move toward the first electrode 42 through the first semiconductor layer 124 and the first photoelectric conversion unit 110 and are collected, and holes pass through the second semiconductor layer 126 to the second electrode 44. ) and collected.

4 is an energy band diagram schematically illustrating energy bands of the solar cell shown in FIG. 3 and the solar cell according to Comparative Example 1; In FIG. 4 , illustration of the second intermediate film, the second electrode layer of the first electrode, and the second electrode is omitted.

Here, in the solar cell according to Comparative Example 1, the second semiconductor layer 126 is made of an amorphous portion rather than a polycrystalline portion.

Referring to FIG. 4 , the present example has an energy band diagram in which holes and electrons smoothly move in the first photoelectric converter 110 and the second photoelectric converter 120 . That is, in each of the first photoelectric converter 110 and the second photoelectric converter 120, the conduction band energy tends to gradually decrease in the direction of electron flow, and the energy of the valence band gradually decreases in the direction of electron flow. has a tendency to increase to That is, since the first semiconductor layer 124 is composed of an amorphous portion having a low energy band gap (1.5 to 1.7 eV) to form an energy band diagram in which carriers can flow smoothly, carrier movement characteristics are excellent.

In addition, the high-concentration first conductivity type poly layer 134 and the second conductivity type poly layer 136 are applied as the bonding layer 130 so that electrons and holes due to carrier tunneling in the polysilicon layer recombine through excessive doping. can Due to such recombination, the number of minority carriers passing through the first conductive poly layer 134 is rapidly reduced, and the junction tunneling layer 132 having a very large energy band gap, for example, 9.0 eV, is formed. The number of passing minority carriers is reduced so that carrier movement is not significantly affected. In addition, the junction tunneling layer 132 is formed with a very thin thickness to give a tunneling effect.

And, compared to the solar cell according to Comparative Example 1 in which the second semiconductor layer 126 located on the rear side is composed of an amorphous portion, the solar cell according to this example has a slightly different band gap in the second semiconductor layer 126, but It can be seen that this difference does not have a significant effect on the carrier movement characteristics related to the carrier flow. Considering this, in the solar cell according to the present example, the efficiency of the solar cell is improved by configuring the second semiconductor layer 126 as a polycrystalline part in consideration of the carrier mobility side rather than the band gap side.

FIG. 4 shows the structure of the solar cell 100 shown in FIG. 3 as an example. Even when the conductivity types of the semiconductor substrate 122 and the first and second semiconductor layers 124 and 126 are different, the tendency of the energy band diagram may have a tendency to improve carrier transfer characteristics.

As described above, according to the present embodiment, while applying the laminated structure of the second conductive poly layer 136 and the first conductive poly layer 134 as the bonding layer 130, a thin tunneling layer 132 is applied to the lower portion. , Carrier movement characteristics may be improved by improving compatibility with the first photoelectric conversion unit 110 including the perovskite compound formed thereon. In addition, it is possible to improve passivation characteristics by configuring the bonding layer 130 with a hydrogenated poly part. Also, since the second semiconductor layer 126 is composed of a polycrystalline portion having excellent carrier mobility, carrier mobility may be improved, material cost of the second electrode 44 may be reduced, and a manufacturing process may be simplified. As a result, the efficiency and productivity of the solar cell 100 having a tandem structure can be improved.

A method of manufacturing the solar cell 100 having the above structure will be described in detail with reference to FIGS. 5 to 12B. Detailed descriptions of the contents already described in the above description will be omitted, and parts that have not been described will be described in detail.

5 is a flow chart of a method for manufacturing a solar cell according to an embodiment of the present invention, FIG. 6 is a detailed flow chart up to formation of the doped layer of FIG. 5, and FIGS. 7A and 7B are for explaining the manufacturing method of FIG. 8 is a detailed flow chart up to hydrogen injection in FIG. 5, FIGS. 9A to 9D are cross-sectional views showing the manufacturing method of FIG. 8, and FIG. 10 is a detailed flow chart showing the completion of the bonding layer in FIG. 11 is a cross-sectional view showing the manufacturing method of FIG. 10, FIG. 12 is a detailed flowchart of forming the first photoelectric conversion unit and electrodes of FIG. 5, and FIGS. 13A and 13B are cross-sectional views showing the manufacturing method of FIG. 11 admit.

Referring to FIG. 5 , the manufacturing method of the solar cell 100 according to the present embodiment includes forming a tunneling layer on both sides of the second photoelectric conversion unit (S10), forming a doped layer (S20), and first and second semiconductor layers. A forming step (S30), a hydrogen injection step (S40), a bonding layer forming step (S50), a first photoelectric converter forming step (S60), and an electrode forming step (S70) are included.

Referring to FIG. 6 , five steps may be included up to the doping layer forming step (S20).

Specifically, first, a semiconductor substrate 122 composed of a base region having a first or second conductivity type dopant is prepared. In this case, at least one of the front and rear surfaces of the semiconductor substrate 122 may be textured to have irregularities to form an anti-reflection structure (S11). Wet or dry texturing may be used for texturing the surface of the semiconductor substrate 122 . Wet texturing may be performed by immersing the semiconductor substrate 122 in a texturing solution, and double-sided texturing may be performed by immersing the semiconductor substrate 122 in a TMAH or KOH solution.

Meanwhile, as shown in FIG. 7A, when texturing is to be performed only on the rear surface, a front surface polishing process may be additionally performed (S12). The backside polishing process may be performed by dipping only one side in an etching solution, may be performed in an acid solution of HF or HNO ₃ , or a conveyor method or a floating method may be applied. In addition, the semiconductor substrate 122 may be textured by reactive ion etching (RIE) or the like. As such, in the present invention, the semiconductor substrate 122 may be textured in various ways.

Subsequently, as shown in FIG. 7A, the second intermediate layer 126a and the junction tunneling layer 132 are formed on both sides of the semiconductor substrate 122 (S13).

The second intermediate layer 126a and the junction tunneling layer 132 may be formed by, for example, a thermal oxidation method or a deposition method (eg, chemical vapor deposition (CVD) or atomic layer deposition (ALD)). Specifically, after polishing, cleaning of both sides is performed, and oxidation is performed by applying DIO ₃ and H ₂ O ₂ to both sides of the cleaned semiconductor substrate in a wet method, and thermal oxidation in a furnace is performed in a dry method, UVO can be performed. The silicon oxide film thus formed may function as the second intermediate layer 126a on the semiconductor substrate 122 and may function as the junction tunneling layer 132 on the front surface.

Silicon oxide films formed on the front and rear surfaces are formed to have a thickness less than 2 nm so that tunneling can be performed.

Next, as shown in FIG. 7B, intrinsic polysilicon layers 134a and 126b are formed on both surfaces (S21).

The intrinsic polysilicon layers 134a and 126b thus formed are entirely formed on the front and back surfaces of the semiconductor substrate 122, and optionally on the side surfaces, and then the intrinsic polysilicon layers 134a and 126b formed on the side surfaces of the semiconductor substrate 122. ), the intrinsic polysilicon layers 134a and 126b may be formed only on the front and rear surfaces of the semiconductor substrate 122 .

For example, the intrinsic polysilicon layers 134a and 126b may be formed by a thermal oxidation method, a vapor deposition method (eg, chemical vapor deposition (CVD), atomic layer deposition (ALD)), or the like. For example, the intrinsic polysilicon layers 134a and 126b may be formed by a deposition method (eg, chemical vapor deposition (CVD), for example, low pressure chemical vapor deposition (LPCVD)), or the like. In this embodiment, the intrinsic polysilicon layers 134a and 126b may be formed of a polycrystalline portion made of a semiconductor material that does not contain a dopant. The intrinsic polysilicon layers 134a and 126b may be formed to a thickness of 100 nm or less at 600° C. or less in an SiH ₄ atmosphere by a low-pressure chemical vapor deposition method.

Next, a doped layer 128 is formed on the backside intrinsic polysilicon layer 126b (S22).

The doped layer 128 may be formed by atmospheric pressure chemical vapor deposition or plasma enhanced chemical vapor deposition (APCVD or PECVD), and when the second semiconductor layer 126 is formed on the rear surface of the semiconductor substrate 122, the second semiconductor When the layer 126 is p-type, boron silicate glass (BSG) or undoped silicate glass (USG) may be deposited and used as a doping source. At this time, while depositing in an atmosphere of SiH ₄ , O ₂ , B ₂ H ₂ , H ₂ , the thickness of the doped layer 128 is formed to satisfy 80 to 150 nm.

Next, the second photoelectric converter 120 is formed as shown in FIGS. 8 and 9C.

As shown in FIG. 9A , a first doped layer 134b is formed on the entire surface of the semiconductor substrate 122 . In this case, the first doped layer 134b may form phosphosilicate glass (PSG) when the first conductivity type is n-type.

Accordingly, PSG is formed as the first doped layer 134b on the front surface of the semiconductor substrate 122, and BSG/USG is formed as the doped layer 128 holding the second type dopant on the rear surface.

Next, heat treatment is performed to dope the underlying intrinsic polysilicon layers 134a and 126b (S31).

Specifically, it is activated to form a first conductivity type region and a second semiconductor layer as shown in FIG. 9B.

Specifically, when heat treatment is performed at a temperature of 900° C. or more in a POCl ₃ atmosphere in a furnace equipment, the intrinsic polysilicon layers 134a and 126b formed on the front and rear surfaces of the substrate 122 are stacked thereon, respectively. Doping proceeds by dopant diffusion from the doped layers 134b and 128, and recrystallization occurs.

Accordingly, the second dopant is diffused on the rear surface to form a poly structure semiconductor layer having the second semiconductor layer 126, and the first dopant is diffused on the front surface from the first doped layer 134b. At this time, diffusion is intrinsic It passes through the junction tunneling layer 132 as well as the polysilicon layer 134a and proceeds to the top surface of the semiconductor substrate 122 in contact with the junction tunneling layer 132 .

Accordingly, a first semiconductor layer 124 doped more heavily than the semiconductor substrate 122 is formed on the top of the semiconductor substrate 122, and the first semiconductor layer 124 has the same amorphous structure as the semiconductor substrate 122. It may have a crystalline structure.

Meanwhile, the intrinsic polysilicon layer 134a formed on the junction tunneling layer 132 is doped with the first dopant at a high concentration, and thus has a higher doping concentration than the first semiconductor layer 124 . ) to form

At this time, the doped layer 128 formed on the lower portion of the substrate 122 serves as a diffusion barrier of the first dopant during formation and diffusion of the first doped layer 134b formed on the upper portion of the second semiconductor layer ( 126), only the second dopant may be diffused.

Next, as shown in FIG. 9B, the first conductive poly layer 134 is formed on the entire surface of the substrate 122 by removing all of the doped layer 134b and the first doped layer 128 remaining on the top and bottom of the semiconductor substrate 122. ) may be exposed, and the second semiconductor layer 126 may be exposed to the rear surface of the substrate 122 (S32).

Such cleaning and removal of the doped layer may be performed by etching with DHF, but is not limited thereto.

Next, hydrogen is implanted into both surfaces of the semiconductor substrate 122 (S40).

In the hydrogen implantation step, hydrogen is implanted into the first conductive poly layer 134 and the second semiconductor layer 126 . As described above, since the first conductivity type poly layer 134 and the second semiconductor layer 126 are formed at a high temperature of 900 degrees Celsius or higher or 600 to 800 degrees Celsius, the first conductivity type poly layer 134 and the second conductivity type poly layer 134 and the second Even if hydrogen is included in the semiconductor layer 126, it can be dehydrogenated by high temperature. Therefore, after forming the first conductive poly layer 134 and the second semiconductor layer 126, a hydrogen injection step is performed to increase the hydrogen content so that hydrogen passivation occurs sufficiently.

In FIG. 9C , for example, a hydrogen injection layer 134c containing hydrogen is formed on the first conductive poly layer 134 and the second semiconductor layer 126 of the semiconductor substrate 122, and a temperature higher than room temperature (day For example, injecting hydrogen by heat treatment at 400 to 600 degrees Celsius) was exemplified (S41). Here, as the hydrogen injection layer 134c, an insulating layer capable of containing a high hydrogen content, for example, a silicon nitride layer containing hydrogen, an aluminum oxide layer containing hydrogen, or the like may be used. In FIG. 9D, it is illustrated that the hydrogen injection layer 134c is removed after the hydrogen injection step (S42). However, the present invention is not limited thereto, and the remaining hydrogen injection layer 134c may be used as a rear passivation film, a reflective film, or an anti-reflective film. Various other methods are possible.

And, the hydrogen injection method of the hydrogen injection step is not limited to the above method. For example, at a temperature higher than room temperature (eg, 400 to 600 degrees Celsius) in a mixed gas atmosphere in which hydrogen gas and a carrier gas (eg, argon gas (Ar), nitrogen gas (N ₂ ), etc.) are mixed. Heat treatment may also be used to inject hydrogen. In addition, hydrogen may be injected using a hydrogen plasma or the like.

When the injection of hydrogen into the first conductive poly layer 134 and the second semiconductor layer 126 is completed as described above, the second conductive poly layer 136 is formed on the first conductive poly layer 134 as shown in FIG. 10 . form

The second conductive poly layer 136 can be deposited on the first conductive poly layer 134 using low pressure, atmospheric pressure, plasma chemical vapor deposition (LPCVD, APCVD, PECVD) equipment, SiH ₄ , B ₂ H It can be deposited at a temperature of 600 ℃ or less in an atmosphere of ₆ (S51).

In this case, the second conductive poly layer 136 may be laminated to a thickness of 50 nm or less. At this time, the doping concentration of the second conductive poly layer 136 may be higher than that of the second semiconductor layer 126, but the doping concentration of the second conductive poly layer 136 is higher than that of the first conductive poly layer ( 134) may be less than or equal to the doping concentration.

Meanwhile, the deposition of the second conductivity-type poly layer 136 may also be performed using a double-sided deposition method. In the case of forming in this double-side deposition method, the first conductive poly layer 134 is attached to the two semiconductor substrates 122 so as to be exposed to the outside, and then the exposed first conductive poly layer 134 on both sides ), the second conductive poly layer 136 may be deposited on it.

In the case of depositing the second conductive poly layer 136 on the two substrates 122 at the same time as described above, the separation of the substrates 122 may be performed by adding a laser isolation process or a RIE process for a post-process.

Next, recrystallization may be performed by performing heat treatment, but such a heat treatment process may be omitted (S52). In the case of performing heat treatment, recrystallization may be induced by performing heat treatment in a furnace or oven at 600 degrees or more and within 10 minutes.

The bonding tunneling layer 132, the first conductive poly layer 134, and the second conductive poly layer 136 formed as described above are bonded to the second photoelectric conversion unit 120 and the first photoelectric conversion unit 110. layer 130.

Next, as shown in FIGS. 12 and 13 , a first photoelectric conversion unit and an electrode are formed to form a tandem solar cell.

In the step of forming the first photoelectric conversion unit 110 ( S60 ), the first photoelectric conversion unit 110 is formed on the bonding layer 130 as shown in FIG. 13A . More specifically, the second transmission layer 116, the photoelectric conversion layer 112, and the first transmission layer 114 may be sequentially formed on the bonding layer 130 (S61, S62, and S63).

The second transmission layer 116, the photoelectric conversion layer 112, and the first transmission layer 114 may be formed by various methods, for example, deposition (eg, physical vapor deposition, chemical vapor deposition, etc.) or printing. It can be formed through law, etc. Here, the printing method may include inkjet printing, gravure printing, spray coating, doctor blade, bar coating, gravure coating, brush painting, and slot-die coating. However, the present invention is not limited thereto.

Subsequently, as shown in FIG. 13B , in the electrode forming step ( S70 ), the first electrode 42 and the second electrode 44 may be formed.

That is, the first electrode layer 420 of the first electrode 42 is formed on the first photoelectric conversion unit 110 (more specifically, the first transmission layer 114) (S71), and the first electrode layer 420 A second electrode layer 422 may be formed thereon (S72). In addition, the metal electrode layer 442 of the second electrode 44 may be formed on the second photoelectric converter 120 (more specifically, the second semiconductor layer 126 composed of a polycrystalline portion).

The first electrode layer 420 of the first electrode 42 may be formed by, for example, a vacuum deposition process or a sputtering process. The vacuum deposition process or the sputtering process may be performed at a low temperature, and the first electrode layer 420 of the first electrode 42 may be formed only on the front surface, which is a cross-section. However, the present invention is not limited thereto, and various methods such as a coating method may be applied. Also, in this embodiment, the second electrode layer 422 of the first electrode 42 and the metal electrode layer 442 of the second electrode 44 may be formed. For example, the second electrode layer 422 of the first electrode 42 and the metal electrode layer 442 of the second electrode 44 are formed by applying a low-temperature baking paste containing a metal and a resin and performing hardening heat treatment for curing the same. can form

For example, after forming the first electrode layer 420 of the first electrode 42, for the second electrode layer 422 of the first electrode 42 and the metal electrode layer 442 of the second electrode 44 A hardening heat treatment may be performed in which the low-temperature firing paste is applied and the low-temperature firing paste for the second electrode layer 422 of the first electrode 42 and the metal electrode layer 442 of the second electrode 44 are simultaneously cured. The hardening heat treatment may be performed at a low temperature of 150 degrees Celsius or less to prevent a characteristic change or deterioration of the first photoelectric conversion unit 110 including the perovskite compound.

The forming process of the first electrode layer 420 of the first electrode 42, the application process and heat treatment process of the second electrode layer 422 of the first electrode 42, and the metal electrode layer 442 of the second electrode 44 The order of the coating process and the heat treatment process may be variously modified.

The above description exemplified that the second electrode layer 422 of the first electrode 42 and the metal electrode layer 442 of the second electrode 44 are formed by a printing method to simplify the process. However, the present invention is not limited thereto, and the method of forming the second electrode layer 422 of the first electrode 42 and the metal electrode layer 442 of the second electrode 44, process conditions, etc. may be modified in various ways. .

According to this embodiment, it is possible to improve productivity by forming a solar cell having a tandem type structure having excellent efficiency through a simple manufacturing process. At this time, the process temperature such as the electrode forming step (ST70) performed after the first photoelectric conversion unit forming step (ST60) of forming the first photoelectric conversion unit 110 including the perovskite compound is set to a low temperature (eg For example, it is maintained at 150 degrees Celsius or less) to effectively prevent deterioration of characteristics of the first semiconductor layer 124 composed of an amorphous portion or the first photoelectric conversion unit 110 including a perovskite compound. .

In the present embodiment, an antireflection film is not provided on the front surface of the solar cell 100 because the semiconductor substrate 122 is provided with an antireflection structure or a concavo-convex structure formed by texturing to perform an antireflection role. At this time, the first semiconductor layer 124 located on the entire surface of the semiconductor substrate 122, the bonding layer 130, the second transmission layer 116, the photoelectric conversion layer 112, the first transmission layer 114, the first Concavo-convex or anti-reflection structures corresponding to the concavo-convex or anti-reflection structures formed on the entire surface of the semiconductor substrate 122 may be formed on both surfaces of the first electrode layer 420 as they are. As such, since a separate antireflection structure is not provided, the structure can be simplified. However, the present invention is not limited thereto, and as shown in FIG. 12B , an antireflection film 460 may be further provided on at least a portion of the first electrode layer 420 of the first electrode 42 . Various other modifications are possible (S73).

And, in this embodiment, a separate passivation film is not provided on the second semiconductor layer 126, so it is illustrated that it has a simple structure. This is because the second semiconductor layer 126 may have excellent passivation characteristics by including hydrogen in a sufficient amount by the hydrogen injection step, so that the effect obtained by leaving the passivation film may not be large. However, the present invention is not limited thereto.

14 is a schematic cross-sectional view of a solar cell according to another embodiment of the present invention.

Referring to FIG. 14 , an optical film 128 may be further provided on the second semiconductor layer 126 . The optical film 129 may play various roles, such as a reflective film for inducing reflection of internal light and an anti-reflection film for preventing reflection of external light. For example, in a double-sided light-receiving solar cell in which the second electrode layer 422 has a certain pattern and receives light on both sides, an optical film 129 is formed on the second semiconductor layer 126 to enter the solar cell 100. The amount of incident light can be maximized. However, the present invention is not limited thereto, and an optical film 129 may be provided on the second semiconductor layer 126 even in a single-sided light-receiving solar cell.

In FIG. 14 , the optical film 129 may be formed in various stages and by various methods. That is, the remaining hydrogen injection layer 126b formed to inject hydrogen into the second semiconductor layer may be used as the optical film 129 . In this case, before the forming process of the second electrode 44, an opening through which the second electrode 44 passes may be formed in the optical film 129 using laser ablation or the like. Alternatively, a separate insulating film may be formed before or after the formation process of the second electrode 44 and used as the optical film 129 . In this case, an opening for penetrating the second electrode 44 or an opening for connecting the second electrode 44 to a wiring material, an interconnector, a ribbon, or the like is formed in the optical film 129 in the process of forming the optical film 129. It may be formed during or after the forming process of the optical film 129 .

For example, the optical film 129 is any one selected from the group consisting of a silicon nitride film, a silicon nitride film including hydrogen, a silicon oxide film, a silicon oxynitride film, an aluminum oxide film, a silicon carbide film, MgF ₂ , ZnS, TiO ₂ and CeO ₂ It may have a single film or a multilayer structure in which two or more films are combined. For example, the optical layer 129 may include a silicon nitride layer to maximize an antireflection effect of the first photoelectric converter 110 including the semiconductor substrate 122 . However, the present invention is not limited thereto.

In FIG. 14 , it is illustrated that the other surface (eg, the rear surface) of the semiconductor substrate 122 is not provided with a concavo-convex or anti-reflection structure. That is, the other surface of the semiconductor substrate 122 may be provided as a flat surface having a smaller surface roughness than one surface of the semiconductor substrate 122 . Accordingly, both surfaces of the second intermediate film 126a and the second semiconductor layer 126 located on one surface of the semiconductor substrate 122 may also be provided with a flat surface having smaller surface roughness than the other surface of the semiconductor substrate 122. 11 illustrates that the optical film 129 is provided on the second semiconductor layer 126 when the other surface of the semiconductor substrate 122 is configured as a flat surface. However, the present invention is not limited thereto. Therefore, as shown in FIG. 1, when the other surface of the semiconductor substrate 122 is provided with a concavo-convex or anti-reflection structure, an optical film 129 is additionally formed on the second semiconductor layer 126 to further improve light reception characteristics. may be At this time, the optical film 129 may entirely expose the metal electrode layer 442 of the second electrode 44 on the second semiconductor layer 126, or a portion of the metal electrode layer 442 of the second electrode 44 ( For example, a finger electrode) may be covered and a part (eg, a bus bar electrode) may be exposed. Various other variations are possible.

The solar cell of the present invention formed as described above has characteristics shown in FIGS. 15 and 16 .

15A and 15B show conductivity characteristics showing leakage current reduction between the present invention and Comparative Example 1, and FIG. 15 shows reflectivity improvement according to the present invention.

In the case of FIG. 15A, the bonding layer 130 is formed as a general conductive layer, and the lateral conductivity between the lower photoelectric conversion unit 120 and the upper photoelectric conversion unit 110 is measured to be very high. Therefore, there is a very high probability that a pin hole is generated due to the combination of holes and electrons on the surface, and the open-circuit voltage due to the short-circuit current is lowered.

On the other hand, as shown in FIG. 15B of the present invention, when the bonding layer 130 is formed in a laminated structure of the high-concentration first conductive poly layer 134 and the second conductive poly layer 136, the vertical conductivity is very low. There are no pinholes on the top surface. Therefore, since minority carriers recombine between the first conductive poly layer 134 and the second conductive poly layer 136 and do not combine with holes on the surface, the open-circuit voltage becomes very high.

In addition, in the case of the present invention, when the bonding layer 130 is formed of a poly layer as shown in FIG. 16, it can be seen that the reflectance rapidly decreases in the long wavelength band. This is obtained by the occurrence of diffuse reflection in the poly structure, and since the reflectivity is lowered, compared to Comparative Example 2 in which the bonding layer 130 is formed of ITO, an increase in current due to light transmission of a very high long-wavelength range can be obtained from the lower part.

In addition, by forming the bonding layer 130 with a poly layer, process consistency and surface shape influence with the first photoelectric conversion unit 110 formed thereon can be improved. Specifically, ITO and the electron transport layer, the first transmission The fact that the layers 116 tend to agglomerate with each other can compensate for the very poor coverage.

That is, in the present invention, the surface energy difference does not occur much, so the coverage is improved and the process consistency is improved.

Features, structures, effects, etc. according to the above are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, etc. illustrated in each embodiment can be combined or modified with respect to other embodiments by those skilled in the art in the field to which the embodiments belong. Therefore, contents related to these combinations and variations should be construed as being included in the scope of the present invention.

100: solar cell
10: photoelectric conversion unit
110: first photoelectric conversion unit
112: photoelectric conversion layer
114: first transmission layer
116: second transmission layer
120: second photoelectric conversion unit
122: semiconductor substrate
124: first semiconductor layer
126: second semiconductor layer
42: first electrode
44: second electrode
130: bonding layer
132: junction tunneling layer
134: first conductive poly layer
136: second conductive poly layer

Claims (16)

a photoelectric conversion unit including a first photoelectric conversion unit including a photoelectric conversion layer made of a perovskite compound and a second photoelectric conversion unit including a semiconductor substrate;
a bonding layer formed between the first photoelectric conversion unit and the second photoelectric conversion unit;
a first electrode electrically connected to the photoelectric conversion unit on one surface of the photoelectric conversion unit; and
A second electrode electrically connected to the photoelectric conversion unit on the other surface of the photoelectric conversion unit.
including,
The bonding layer is
A first conductivity-type poly layer formed on the second photoelectric conversion unit and a second conductivity-type poly layer formed on the first conductivity-type poly layer
A solar cell comprising a. According to claim 1,
The second photoelectric converter is formed in the semiconductor substrate on one surface of the semiconductor substrate and has a crystal structure different from that of the first semiconductor layer on a first semiconductor layer of a first conductivity type and on the other surface of the semiconductor substrate. A solar cell comprising a second semiconductor layer having a second conductivity type. According to claim 2,
The first semiconductor layer is formed in the semiconductor substrate and includes an amorphous portion,
The second semiconductor layer located on the rear surface of the semiconductor substrate includes a polycrystalline portion,
The solar cell further comprising a second tunneling layer between the semiconductor substrate and the second semiconductor layer. According to claim 1,
The bonding layer is
The solar cell further comprising a junction tunneling layer formed between the first conductivity type first semiconductor layer and the first conductivity type poly layer. According to claim 3,
The solar cell, characterized in that the doping concentration of the first conductivity-type first semiconductor layer is lower than the doping concentration of the first conductivity-type poly layer. According to claim 4,
The solar cell, characterized in that the junction tunneling layer has a thickness of 3 nm or less. According to claim 6,
A solar cell having an insulating junction structure or a tunnel junction structure in which the semiconductor substrate and the second semiconductor layer are bonded with the second tunneling layer made of an insulating material interposed therebetween. According to claim 6,
A solar cell, characterized in that the doping concentration of the second conductive poly layer is higher than that of the second semiconductor layer. According to claim 8,
The solar cell wherein the junction tunneling layer and the second tunneling layer include an insulating material. According to claim 9,
The solar cell of claim 1 , wherein the junction tunneling layer and the second tunneling layer include silicon oxide. According to claim 1,
the first photoelectric conversion unit is positioned on one surface of the second photoelectric conversion unit;
The first electrode is positioned on the first photoelectric conversion unit,
The second electrode is positioned on the second semiconductor layer of the second photoelectric conversion unit,
The second semiconductor layer includes a polycrystalline portion,
A solar cell in which the first electrode and the second electrode have different laminated structures. A semiconductor substrate, a first semiconductor layer on one surface of the semiconductor substrate, the second semiconductor layer formed separately from the semiconductor substrate on the other surface of the semiconductor substrate and having a crystal structure different from that of the first semiconductor layer, and the first semiconductor forming a bonding layer including a second photoelectric converter including forming a bonding layer on the layer and a first conductive poly layer simultaneously doped with the first semiconductor layer;
forming a first photoelectric conversion unit including a photoelectric conversion layer made of a perovskite compound on the bonding layer; and
forming a first electrode electrically connected to the first photoelectric conversion unit on one surface of the first photoelectric conversion unit and a second electrode electrically connected to the second photoelectric conversion unit on the other surface of the second photoelectric conversion unit;
Method for manufacturing a solar cell comprising a. According to claim 12,
Forming the second photoelectric conversion unit and the bonding layer,
forming an oxide film on both surfaces of the semiconductor substrate;
separately forming an intrinsic poly semiconductor layer on the oxide layer;
forming a first conductivity-type doping layer on the intrinsic poly semiconductor layer positioned on the front surface of the semiconductor substrate, and forming a second conductivity-type doping layer on the intrinsic poly semiconductor layer positioned on the rear surface of the semiconductor substrate; and
heat-treating to form the intrinsic poly semiconductor layer on the rear surface of the semiconductor substrate as a second semiconductor layer of a second conductivity type, and forming the intrinsic poly semiconductor layer on the front surface of the semiconductor substrate as the first conductivity type poly layer;
Method for manufacturing a solar cell comprising a. According to claim 13,
Forming the first conductive poly layer
Manufacturing a solar cell, characterized in that a first conductivity-type dopant from the first conductivity-type doping layer passes through a lower oxide film and diffuses to the entire surface of the semiconductor substrate to simultaneously form a first semiconductor layer of the first conductivity type. method. According to claim 14,
The method of manufacturing a solar cell further comprising a hydrogen implantation step of injecting hydrogen into the first conductive poly layer and the second semiconductor layer after forming the first conductive poly layer. According to claim 15,
The manufacturing method of a solar cell, characterized in that, after the hydrogen injection step, the second conductive poly layer is further formed on the first conductive poly layer to complete the bonding layer.

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