KR20180011832A - Tandem solar cell, tanden solar cell module comprising the same and method for manufacturing thereof - Google Patents

Abstract

The present invention relates to a tandem solar cell, a tandem solar cell module having the same, and a manufacturing method thereof. More specifically, the present invention relates to a monolithic tandem solar cell stacking perovskite solar cells on a front surface of a crystalline silicon solar cell and bonding the solar cells, and a manufacturing method thereof. According to the present invention, by patterning a nanoelectrode structure on a front surface of a front transparent electrode in which the crystalline silicon solar cell and the perovskite solar cell are bonded by using a bonding layer as a medium, an optical path of solar light incident to the solar cell through the nanoelectrode structure is increased so as to improve usability of the solar light.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a tandem solar cell, a tandem solar cell module including the tandem solar cell,

The present invention relates to a tandem solar cell, a tandem solar cell module including the tandem solar cell, and a method of manufacturing the same. More specifically, the present invention relates to a tandem solar cell including a monolithic solar cell in which a perovskite solar cell is laminated on a front surface of a crystalline silicon solar cell, The present invention relates to a tandem solar cell, a tandem solar cell module in which the tandem solar cell is modularized, and a method of manufacturing the same.

Crystalline silicon (c-Si) solar cells are a typical single-junction solar cell and have dominated the solar cell market for decades.

However, although the band gap of crystalline silicon is almost ideal when considering the Shockley-Queisser limit, the photoelectric conversion efficiency of a silicon-based solar cell is limited to approximately 30% according to Auger recombination.

That is, the photovoltaic efficiency of the conventional crystalline silicon solar cell is lowered due to the thermalization loss occurring when a photon having energy much higher than the band gap is incident and the transmission loss of the photon having energy lower than the band gap .

Here, the deterioration loss means that the excess energy of light absorbed by the solar cell is lost as heat energy without being converted into a photon which is a quantum form of lattice vibration, and a photon having energy lower than the band gap does not sufficiently excite electrons .

In order to reduce the deterioration loss in a single junction solar cell, a band gap of a proper size is required and a band gap is required to be low so that a low energy photon contributes, a trade-off relationship is established between the two.

Since such a trade-off relationship is difficult to solve with a single junction solar cell, it has recently been found that by using materials having various energy band gaps such as a tandem solar cell or a double-junction solar cell, Attempts have been made to effectively utilize optical energy.

As one of such attempts, a tandem solar cell constituting one solar cell by connecting a single junction solar cell including an absorption layer having different band gaps has been proposed.

In general, a single junction solar cell including an absorber layer having a relatively large bandgap is positioned on the front side to receive incident light first, and a single junction solar cell including an absorber layer having a relatively small band gap is disposed on the rear surface .

Accordingly, the tandem solar cell absorbs light in a short wavelength region from the front side and absorbs light in a long wavelength region from the rear side, thereby moving the threshold wavelength toward the long wavelength side, and consequently, the entire absorption wavelength region can be widely used There is an advantage.

In addition, by using the entire absorption wavelength region divided into two bands, a reduction in heat loss can be expected in electron-hole generation.

Such a tandem solar cell can be roughly classified into a two-terminal tandem solar cell and a four-terminal tandem solar cell depending on the junction type of the single junction solar cell and the position of the electrode.

Specifically, a two-terminal tandem solar cell has a structure in which two sub-solar cells are tunnel-junctioned, and electrodes are provided on the front and rear surfaces of the tandem solar cell. In the four- And the electrodes are provided on the front and rear surfaces of each sub solar cell.

In the case of a four-terminal tandem solar cell, each sub-solar cell requires a separate substrate and requires a relatively large number of transparent conductive junctions compared to a two-terminal tandem solar cell, resulting in high resistance and inevitable optical loss Terminal tandem solar cell is attracting attention as a next generation solar cell.

1 schematically shows a cross-section of a general two-terminal tandem solar cell.

Referring to FIG. 1, a solar cell includes a single junction solar cell including an absorption layer having a relatively large bandgap and a single junction solar cell including an absorption layer having a relatively small band gap, through a junction layer.

A single junction solar cell including an absorption layer having a relatively large bandgap among various types of two-terminal tandem solar cells is used as a perovskite solar cell and a single junction solar cell including an absorption layer having a relatively small band gap Has been attracting attention as a candidate for achieving a photovoltaic efficiency of 30% or more in a perovskite / crystalline silicon tandem solar cell using a crystalline silicon solar cell.

In a perovskite / crystalline silicon tandem solar cell, a perovskite solar cell is deposited on the front surface of a junction layer after forming a junction layer on the whole surface of the crystalline silicon solar cell.

In this case, when the texture structure is formed on the surface of the crystalline silicon substrate to reduce the reflectance of the incident light, the perovskite solar cell (particularly, the electron transport layer directly contacting the crystalline silicon solar cell) is not uniformly deposited there is a problem.

Therefore, at present, most perovskite / crystalline silicon tandem solar cells are formed by flattening the surface of a crystalline silicon substrate on which a perovskite solar cell is deposited, and then depositing a perovskite solar cell.

In this case, not only the reflectance of the incident light is increased but also the optical path length of the long wavelength absorbed by the crystalline silicon tandem solar cell arranged on the rear side is reduced, so that the light absorption rate in the crystalline silicon tandem solar cell is lowered.

In addition, incident light of a short wavelength selectively absorbed by the perovskite solar cell disposed on the front surface may not be sufficiently collected in the perovskite absorption layer, and there is a fear that the transmission loss problem due to the penetration may occur.

Accordingly, the present invention provides a tandem solar cell having a structure capable of increasing the light path by reducing the reflectance of light vertically incident on the tandem solar cell and changing the incidence direction of the light in an oblique direction, and a tandem solar cell And to provide a battery module.

It is another object of the present invention to provide a tandem solar cell module having a structure capable of selectively collecting light in a perovskite solar cell and a crystalline silicon solar cell.

It is another object of the present invention to provide a tandem solar cell module having improved light efficiency and the total amount of semiconductor panels by using a homogeneous or heterogeneous silicon solar cell of double-side light receiving type.

Another object of the present invention is to provide a method of manufacturing a tandem solar cell capable of reducing a reflectance of an incident light and increasing a light path by introducing a patterned nano optical structure on the front surface of the tandem solar cell.

According to one aspect of the present invention, in order to solve the problems of uniform deposition of the perovskite solar cell and reduction in the light absorption rate due to reduction of the optical path of the long wavelength absorbed in the crystalline silicon tandem solar cell, A perovskite solar cell positioned on the front surface of the bonding layer, and a front transparent electrode disposed on the front surface of the perovskite solar cell, wherein the front transparent electrode has a patterned transparent electrode structure A tandem solar cell is provided.

Here, as the transparent electrode structure is patterned so as to have a concave-convex pattern or a grid pattern, it is possible to change the direction of light vertically incident on the tandem solar cell in an oblique direction, thereby reducing the reflectance of incident light and increasing the light path . As the path of the incident light increases, the path of the light passing through the light absorption layer in the perovskite solar cell and the crystalline silicon solar cell increases, thereby improving the light absorption rate.

Here, the front metal electrode for collecting charges generated in the perovskite solar cell is disposed in a part of the front surface of the front transparent electrode. At this time, the front metal electrode includes a pad electrode made of a metal and an electrode wire. Here, when forming a solar cell module using a plurality of tandem solar cells (i.e., a plurality of cells) according to the present invention, the electrode wires serve as conductors for electrically connecting neighboring cells. At this time, the electrode wire has a cylindrical or elliptical cross section, so that the incident light reflected by the electrode wire can be re-incident toward the solar cell.

In addition, the rear metal electrode for collecting charges generated in the crystalline silicon solar cell is not entirely provided on the rear surface of the rear transparent electrode but is disposed in a part of the rear surface of the rear transparent electrode or the rear surface of the rear passivation layer, So that light of a long wavelength which can not be absorbed by the absorption layer of the crystalline silicon solar cell can be transmitted to the outside.

At this time, the rear metal electrode may be disposed on the rear transparent electrode or a part of the rear surface of the rear passivation layer so that solar light can be incident on the rear surface as well as the front surface of the tandem solar cell.

According to another aspect of the present invention, there is provided a solar cell comprising: a junction layer positioned on a flat front surface of a crystalline silicon solar cell; a perovskite solar cell positioned on a front surface of the junction layer; Electrode, a transparent electrode structure disposed on the front surface of the front transparent electrode and including a patterned transparent electrode, a front metal electrode disposed on a front surface of the transparent electrode structure, and a rear metal electrode disposed on a rear surface of the crystalline silicon solar cell, The tandem solar cell module includes a plurality of tandem solar cells.

At this time, the front metal electrode and the rear metal electrode of the neighboring two tandem solar cells of the plurality of tandem solar cells are electrically connected to each other by the electrode wire, and a gap is formed on the front and rear surfaces of the plurality of tandem solar cells A front transparent substrate and a rear transparent substrate.

According to another aspect of the present invention, there is provided a method for manufacturing a solar cell, comprising: forming a crystalline silicon solar cell from a crystalline silicon substrate; forming a bonding layer on a flat front surface of the crystalline silicon solar cell; forming a perovskite solar cell Forming a front transparent electrode on the front surface of the perovskite solar cell, and patterning the transparent electrode structure on the front surface of the front transparent electrode.

Here, the transparent electrode structure may be patterned so as to have a concave-convex pattern or a grid pattern by etching a predetermined depth from the front surface of the front transparent electrode after the front transparent electrode is formed, or may be deposited as a separate layer on the front surface of the front transparent electrode have.

According to the present invention, by arranging a patterned transparent electrode structure on the front surface of the front transparent electrode disposed on the front surface of the tandem solar cell, it is possible to reduce the reflectance of the incident light by changing the incident angle of the light vertically incident on the front surface of the tandem solar cell It is possible.

In particular, even if a texture structure is not introduced on the front surface of the crystalline silicon solar cell, the light of a long wavelength transmitted through the perovskite solar cell is incident on the crystalline silicon solar cell in the diagonal direction, It is possible to reduce the reflection.

In addition, the light incident vertically toward the tandem solar cell can be refracted by the patterned transparent electrode structure on the front surface of the front transparent electrode and incident on the perovskite solar cell and the crystalline silicon solar cell in the diagonal direction. As a result, the path of incident light passing through each solar cell is increased, and as a result, the light absorption rate in each solar cell can be improved.

Further, according to the present invention, as the electrode wire for collecting the charge generated in the perovskite solar cell of the tandem solar cell has a cylindrical or elliptical cross section, the incident light reflected by the electrode wire is directed toward the solar cell So that the efficiency can be improved.

In addition, since the rear metal electrode is disposed in a partial region, it is possible to realize a double-side light receiving type tandem solar cell, thereby further improving the efficiency of the tandem solar cell.

1 schematically shows a cross section of a general tandem solar cell.
2 is a cross-sectional view of a tandem solar cell according to an embodiment of the present invention.
FIGS. 3 and 4 show another embodiment of the transparent electrode structure applied to the tandem solar cell shown in FIG.
5 and 6 schematically show a path for absorbing short-wavelength light in the tandem solar cell shown in Fig.
FIGS. 7 and 8 schematically show a path for absorbing long wavelength light in the tandem solar cell shown in FIG. 2. FIG.
9 is a cross-sectional view of a tandem solar cell according to another embodiment of the present invention.
FIGS. 10 and 11 show another embodiment of the transparent electrode structure applied to the tandem solar cell shown in FIG.
FIG. 12 shows a manufacturing procedure of the tandem solar cell shown in FIG. 2. FIG.
FIG. 13 shows a manufacturing procedure of the tandem solar cell shown in FIG.
14 schematically shows a modular form of the tandem solar cell according to the present invention.

Hereinafter, a tandem solar cell according to a preferred embodiment of the present invention and a method for manufacturing the same will be described in detail with reference to the accompanying drawings.

It is to be understood that the present invention is not limited to the disclosed embodiments, but may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to inform.

[Tandem Solar Cell]

The tandem solar cell described below is generally assumed to be a double-side receive-type tandem solar cell capable of receiving both sunlight (or incident light) from the front and rear surfaces of the tandem solar cell, rather than receiving only the front surface of the tandem solar cell .

1st Example

2 is a cross-sectional view of a tandem solar cell according to a first embodiment of the present invention.

Referring to FIG. 2, the tandem solar cell according to the first embodiment of the present invention includes a perovskite solar cell 130 including an absorption layer having a relatively large bandgap and an absorption layer having a relatively small band gap Terminal tandem solar cell (hereinafter referred to as "perovskite / crystalline silicon tandem solar cell") in which a crystalline silicon solar cell 110 is directly tunnel-bonded via a bonding layer 120 .

Accordingly, the light in the short wavelength region of the light incident on the tandem solar cell is absorbed by the perovskite solar cell 130 disposed on the front side to generate electric charge, and the light of the long wavelength region transmitted through the perovskite solar cell Is absorbed by the crystalline silicon solar cell 110 disposed on the rear surface to generate electric charges.

The tandem solar cell having the above-described structure absorbs the light in the short wavelength region in the perovskite solar cell 130 disposed on the front side and generates light in the long wavelength region in the crystalline silicon solar cell 110 disposed on the rear side The threshold wavelength can be shifted toward the longer wavelength side, and as a result, the advantage is obtained that the wavelength band absorbed by the entire solar cell can be widened.

However, in the case of a two-terminal tandem solar cell, since the perovskite solar cell 130 is directly tunnel-bonded to the front surface of the silicon solar cell 110 via the bonding layer 120, The characteristics of the perovskite solar cell 130 may be influenced by the structure of the front surface of the cell 110. [

In a single junction solar cell, it is common to introduce a texture structure on the surface to reduce the reflectance of the incident light on the surface and increase the path of the light incident on the solar cell.

However, in the case of the perovskite / crystalline silicon tandem solar cell, it is difficult to uniformly deposit the perovskite solar cell on the front surface of the crystalline silicon tandem solar cell when the texture structure is introduced on the whole surface of the crystalline silicon tandem solar cell there is a problem. As a result, most of the perovskite / crystalline silicon tandem solar cells known so far have had limitations that must be realized on the entire surface of a flat wafer.

In this case, there is a problem that the probability that the light in the long wavelength region vertically incident on the crystalline silicon solar cell through the perovskite solar cell is reflected at the interface between the junction layer and the crystalline silicon solar cell increases in particular. In addition, even when a crystalline silicon solar cell is transmitted without reflection, there is a problem that it is difficult to improve the absorption rate of long wavelength light because the optical path of a long wavelength is shorter than that of a case where it is incident on a diagonal line.

In order to solve the problem of the conventional perovskite / crystalline silicon tandem solar cell, in the tandem solar cell according to the first embodiment of the present invention, the crystalline silicon solar cell 110 has a selective texture structure only on the rear surface .

The crystalline silicon solar cell 110 according to the first embodiment may be implemented with a heterojunction crystalline silicon solar cell.

Specifically, the crystalline silicon solar cell 110 according to the first embodiment includes a crystalline silicon substrate 111, a front i-type amorphous silicon layer 112 located on the front surface of the crystalline silicon substrate 111, and a front i- And a first conductive amorphous silicon layer 114 located on the front surface of the layer. The front surface of the crystalline silicon substrate 111 is a portion where light in a long wavelength region transmitted through the perovskite solar cell 130 is incident on the crystalline silicon solar cell 110 for the first time.

The rear surface of the crystalline silicon substrate 111 includes a rear i-type amorphous silicon layer 113 and a second conductive amorphous silicon layer 115 positioned on the rear surface of the rear i-type amorphous silicon layer 113.

Here, when the crystalline silicon substrate 111 is an n-type single crystal silicon substrate, the first conductive amorphous silicon layer 114 is preferably a p-type amorphous silicon layer. That is, in order to improve the carrier mobility at the front surface where the amount of received light is relatively high as the light in the long wavelength region is first incident on the crystalline silicon solar cell 110, a p-type amorphous silicon layer is placed on the entire surface of the n- It is preferable to configure reverse bonding (pn junction), thereby improving the collection efficiency of the carrier. In this case, the second conductive amorphous silicon layer 115 uses an n-type amorphous silicon layer to obtain a back surface electric field effect.

In addition, as the crystalline silicon substrate 111, a p-type single crystal silicon substrate instead of the n-type single crystal silicon substrate or another crystalline silicon substrate commonly used for the crystalline silicon solar cell 110 may be used. Similarly, the first conductive amorphous silicon layer 114 and the second conductive amorphous silicon layer 115 may also be designed to have a suitable conductive type according to the conductive type of the crystalline silicon substrate 111.

The electric charge generated in the crystalline silicon solar cell 110 is collected in the rear transparent electrode 140 and the connection between the rear transparent electrode 140 and the external terminal is made via the rear metal electrode 180.

The rear transparent electrode 140 may be implemented as a variety of transparent conductive materials.

Examples of the transparent conductive material for implementing the rear transparent electrode 140 include a transparent conductive oxide, a carbonaceous conductive material, a metallic material, and a conductive polymer.

Examples of the transparent conductive oxide include indium tin oxide (ITO), indium cerium oxide (ICO), indium tungsten oxide (IWO), zinc indium tin oxide (ZITO), zinc tin oxide (ZIO) Gallium indium tin oxide (GIO), gallium indium oxide (GIO), gallium zinc oxide (GZO), aluminum doped zinc oxide (AZO), fluorine tin oxide (FTO) As the carbonaceous conductive material, graphene or carbon nanotube may be used. As the metallic material, a metal thin film of a multi-layer structure such as a metal (Ag) nanowire or Au / Ag / Cu / Mg / have. Examples of the conductive polymer include polyaniline, polypyrrole, polythiophene, poly-3,4-ethylene dioxythiophene-polystyrene sulfonate (PEDOT-PSS), poly- [bis Methylphenyl) amine] (PTAA), Spiro-MeOTAD or polyaniline-camphorsulfonic acid (PANI-CSA) may be used.

2, the rear metal electrode 180 is provided not on the entire rear surface of the rear transparent electrode 140 but on a part of the rear surface of the rear transparent electrode 140, Solar light may be incident from the rear surface of the battery 110. [

At this time, it is preferable that the rear metal electrode 180 is arranged to occupy 1% to 30% of the total area of the rear surface of the rear transparent electrode 140. If the area occupied by the rear metal electrode 180 is less than 1%, the effect of trapping charges generated in the crystalline silicon solar cell 110 by the rear metal electrode 180 may be insufficient. On the other hand, The area occupied by the rear metal electrode 180 is excessively wide, which may lower the utilization rate of light incident from the rear surface of the crystalline silicon solar cell 110. [

The rear metal electrode 180 includes a pad electrode 181 that contacts a part of the rear surface of the rear transparent electrode 140. In addition, a grid electrode structure for collecting charges may be formed on the rear surface of the rear transparent electrode 140, and a pad electrode 181 may be provided on a part of the rear surface of the grid electrode structure. An electrode wire 182 is provided to electrically connect the neighboring tandem solar cell (cell) to the rear surface of the pad electrode 181. An electrode wire 182 connected to the rear surface of the pad electrode 181 of one cell, Is integrally formed with the electrode wire 172 connected to the front surface of the pad electrode 171 of the neighboring cell.

Here, the electrode wire 182 is preferably a wire having a cylindrical or elliptical cross section. Accordingly, the light incident from the rear surface of the crystalline silicon solar cell 110 is reflected in an oblique direction to be incident, thereby increasing the optical path.

In addition, a texture structure is introduced into the rear surface of the crystalline silicon substrate 111, and the silicon layers 113 and 115 and the rear transparent electrode 140 sequentially formed on the rear surface of the crystalline silicon substrate 111 are formed along the texture structure The path of light incident vertically through the rear surface of the crystalline silicon solar cell 110 can be changed to an oblique direction. That is, the light scattering effect by the texture structure introduced to the rear surface of the crystalline silicon solar cell 110 can increase the path of light incident from the rear surface of the crystalline silicon solar cell 110.

When the perovskite solar cell 130 is formed on the front surface of the silicon solar cell 110 by making the front surface of the crystalline silicon substrate 111 flat without introducing the texture structure unlike the rear surface, It is possible to prevent the occurrence of defects in the substrate 130.

A crystalline silicon solar cell 110 and a perovskite solar cell 130 are tunnel-joined to a front surface of the first conductive amorphous silicon layer 114 of the crystalline silicon solar cell 110, Layer 120 is located.

The bonding layer 120 electrically connects the crystalline silicon solar cell 110 and the perovskite solar cell 130 and simultaneously transmits light of a long wavelength transmitted through the perovskite solar cell 130 to the rear surface Such as a transparent conductive oxide, a carbonaceous conductive material, a metallic material, or a conductive polymer, in the same manner as the rear transparent electrode 140 so as to be incident on the crystalline silicon solar cell 110 disposed in the crystalline silicon solar cell 110. The bonding layer 120 may be doped with an n-type or p-type material. For example, it is also possible to apply an n-type or p-type amorphous silicon layer instead of the transparent electrode to the bonding layer 120.

According to another modification, the bonding layer 120 may be implemented as a multi-layer structure in which silicon layers having different refractive indices are alternately stacked a plurality of times. At this time, the multilayer structure may have a structure in which the low refractive index layer and the high refractive index layer are alternately laminated. Accordingly, light of short wavelength based on the bonding layer 120 can be reflected to the side of the perovskite solar cell 130, and light of a long wavelength can be transmitted to the crystalline silicon solar cell 110 side. This makes it possible to selectively capture light of the perovskite / crystalline silicon tandem solar cell.

Here, the above-described selective reflection and transmission of light can be realized by providing a structure in which the low refractive index layer and the high refractive index layer are alternately stacked on the front surface or the back surface of the transparent conductive oxide layer or the n + type silicon layer.

The front surface of the bonding layer 120 is positioned with the perovskite solar cell 130.

The perovskite solar cell 130 includes an electron transport layer 131 located on the front surface of the bonding layer 120, a perovskite absorption layer 132 located on the front surface of the electron transport layer, and a perovskite- And a hole transport layer 133 positioned on the front surface. Here, the positions of the electron transporting layer 131 and the hole transporting layer 133 can be changed as needed.

The electron transport layer 131 located on the front surface of the bonding layer 120 may include a metal oxide. Non-limiting examples of the metal oxide constituting the electron transporting layer 131 include Ti oxide, Zn oxide, In oxide, Sn oxide, W oxide, Nb oxide, Mo oxide, Mg oxide, Zr oxide, Sr oxide, La oxide, V oxide, Al oxide, Y oxide, Sc oxide, Sm oxide, Ga oxide, In oxide and SrTi oxide. Preferably, the electron transport layer 131 may include at least one metal oxide selected from ZnO, TiO ₂ , SnO ₂ , WO _3, and TiSrO ₃ .

Further, the mesoporous layer 131a including the same or different metal oxide as the electron transport layer 131 may be further provided on the entire surface of the electron transport layer 131.

Here, the mesoporous layer 131a allows electrons to be easily transferred to the bonding layer 120 after the hole-electron pair generated in the perovskite absorption layer 132 is decomposed into electrons or holes. In addition, the mesoporous structure formed in the mesoporous layer 131a may serve to further increase the optical path by scattering the transmitted light.

The perovskite absorption layer 132 located on the front surface of the bonding layer 120 is a photoactive layer containing a compound having a perovskite structure. The perovskite structure is AMX ₃ (where A is a monovalent organic Ammonium cation or metal cation, M is a divalent metal metal cation, and X is a halogen anion). Non-limiting examples of the compound having a perovskite structure include 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, (CH 3 NH 3)} (HC (NH 2) 2) 1- y PbI 3, (CH 3 NH 3) (HC (NH 2) 2) 1- y PbI x Cl 3 -x, (CH 3 NH _{3) (HC (NH 2)} 2) 1-y PbI x Br 3-x, or _{(CH 3 NH 3) (HC} (NH 2) 2) 1- y PbCl x Br 3 has such _-x (0≤ x, y? 1). Also, a compound in which A of Cs in AMX ₃ is partially doped can also be used.

At this time, the perovskite absorbing layer 132 is preferably laminated to the front surface of the mesoporous layer 131a at a predetermined height while filling the mesopores of the mesoporous layer 131a in order to improve the electron transfer effect Do.

The hole transport layer 133 located on the front surface of the perovskite absorption layer 132 may be formed of a conductive polymer referred to as a material of the rear transparent electrode 140. The hole transporting layer 133 may further include an n-type or p-type dopant, if necessary.

Electric charges generated in the perovskite solar cell 130 having the above structure are collected in the front transparent electrode 150 and the connection between the front transparent electrode 150 and the external terminal is transmitted through the front metal electrode 170 .

The front transparent electrode 150 may be implemented as various transparent conductive materials as the rear transparent electrode 140.

The tandem solar cell according to an embodiment of the present invention reduces the reflectance of vertically incident light and changes the incidence direction of the light to diagonal direction so as to increase the optical path passing through the tandem solar cell. And a transparent electrode structure 160 patterned in a nano size on the front surface of the transparent electrode structure 160. At this time, the transparent electrode structure 160 may have a lattice pattern such as a grid or a mesh pattern.

That is, by arranging the patterned transparent electrode structure 160 on the front surface of the front transparent electrode 150, it is possible to reduce the reflectance of the incident light by changing the incident angle of the light vertically incident on the tandem solar cell.

In particular, even if a texture structure is not introduced to the front surface of the crystalline silicon solar cell 110, the long wavelength light transmitted through the perovskite solar cell 130 is refracted in the oblique direction by the transparent electrode structure 160, Reflection toward the interface between the bonding layer 120 and the crystalline silicon solar cell 110 can be reduced.

In addition, light incident vertically toward the tandem solar cell is refracted by the patterned transparent electrode structure 160 and is incident on the perovskite solar cell 130 and the crystalline silicon solar cell 110 in an oblique direction . As a result, the path of incident light passing through each solar cell is increased, and as a result, the light absorption rate in each solar cell can be improved.

The transparent electrode structure 160 may be formed of various transparent conductive materials as in the case of the front transparent electrode 150. The transparent electrode structure 160 may be provided as a separate layer from the front transparent electrode 150 or may be integrally formed with the front transparent electrode 150 .

For example, referring to FIG. 2, the front transparent electrode 150 and the transparent electrode structure 160 are provided as separate layers, and the transparent electrode structure 160 has a nano-sized structure or a grid or mesh pattern And the front transparent electrode 150 is exposed in some regions by being patterned.

3, a front transparent electrode 150 and a transparent electrode structure 160 are provided as separate layers, and the transparent electrode structure 160 may be patterned in a concave-convex pattern.

4, the front transparent electrode 150 and the transparent electrode structure 160 may be integrally formed. In this case, after the transparent electrode is deposited, the front transparent electrode 150 and the transparent electrode structure 160 are patterned by a predetermined depth from the front surface The electrode structure 160 can be formed.

The total transparent electrode 150 and the transparent electrode structure 160 are provided according to the various modified examples described above to further improve the light collecting effect of the tandem solar cell.

The front metal electrode 170 is provided in a part of the front surface of the front transparent electrode 150. The front metal electrode 170 includes a pad electrode 171 contacting a part of the front surface of the front transparent electrode 150. In addition, a grid electrode structure for collecting charges may be formed on the front surface of the front transparent electrode 150, and a pad electrode 171 may be provided on a part of the front surface of the grid electrode structure. An electrode wire 172 is provided on the front surface of the pad electrode 171 to electrically connect neighboring tandem solar cells and an electrode wire 172 connected to the front surface of the pad electrode 171 of one cell, Is integrally formed with the electrode wire 182 connected to the rear surface of the pad electrode 181 of the neighboring cell. Here, the pad electrodes 171 and 181 and the electrode wires 172 and 182 may be solder-bonded using a conductive paste or the like.

Here, the electrode wire 172 is preferably a wire having a cylindrical or elliptical cross section. Accordingly, the light incident vertically toward the electrode wire 172 can be scattered to increase the probability of re-entering into the tandem solar cell.

5 and 6 schematically show a path for absorbing short wavelength light in the tandem solar cell shown in FIG. 2, and FIGS. 7 and 8 show a path for absorbing long wavelength light in the tandem solar cell shown in FIG. Fig.

Referring to FIGS. 5 to 8, a transparent substrate 190 is provided on the rear surface of the perovskite / crystalline silicon tandem solar cell shown in FIG. 2 with an encapsulating material 195 sandwiched therebetween. The transparent substrate 200 may be provided with the material 205 interposed therebetween. Here, as the transparent substrates 190 and 200, a glass substrate, a transparent polymer substrate, or the like can be used.

5 shows various paths in which a short wavelength light incident from a front surface of a tandem solar cell in a perovskite solar cell 130 in a tandem solar cell is absorbed.

First, the first optical path (1) is an optical path in which short-wavelength light is refracted by the transparent electrode structure 160 and is incident on the perovskite absorption layer 132 in a diagonal direction. That is, by introducing the patterned transparent electrode structure 160 on the front surface of the perovskite solar cell 130, the path of the light vertically incident on the perovskite solar cell 130 is changed to diagonal direction, The utilization efficiency of the short wavelength light in the perovskite absorbing layer 132 can be improved by the increased optical path while obtaining the effect of preventing the perovskite absorption.

The second optical path (2) and the third optical path (3) are paths through which short-wavelength light is reflected by the front metal electrode 170 including a wire-shaped metal grid having a cylindrical or elliptical cross section.

Here, the second optical path (2) is a light path in which light incident vertically toward the front surface of the front metal electrode 170 is reflected on the curved surface of the electrode wire and is incident on the transparent substrate 200 in the oblique direction . Light incident on the transparent substrate 200 in a diagonal direction may be reflected again and incident on the perovskite solar cell 130 in a diagonal direction.

Accordingly, the light incident vertically toward the front metal electrode 170 can be scattered in various directions to increase the probability of re-entering the perovskite solar cell 130.

The third optical path (3) is an optical path in which light incident vertically toward the side of the electrode wire is reflected and is incident on the perovskite solar cell 130 in an oblique direction. Thus, it is possible to improve the utilization ratio of the short wavelength light in the perovskite absorption layer 132 by the increased optical path while obtaining the antireflection effect.

The fourth optical path (4) is an optical path reflected by the bonding layer 120 and re-incident on the perovskite absorption layer 132. To this end, the bonding layer 120 has a multi-layer structure having different refractive indexes so that light of a short wavelength is reflected to the perovskite absorption layer 132 and light of a long wavelength is transmitted to the crystalline silicon solar cell 110 desirable.

FIG. 6 shows various paths in which the light of a short wavelength incident from the rear surface of the tandem solar cell is absorbed in the perovskite solar cell 130 in the tandem solar cell.

First, the first optical path (1) is a light path in which short-wavelength light is refracted by the texture structure introduced on the rear surface of the crystalline silicon solar cell 110 and is incident on the perovskite solar cell 130 in an oblique direction . That is, by introducing a texture structure on the rear surface of the crystalline silicon solar cell 110, the optical path of a short wavelength vertically incident from the rear surface of the tandem solar cell is changed to diagonal direction to obtain an antireflection effect, The utilization ratio of the short wavelength light in the robust solar cell 130 can be improved.

The second optical path (2) and the third optical path (3) are paths through which short-wavelength light is reflected by the rear metal electrode 180 including a wire-shaped metal grid having a cylindrical or elliptical cross section.

Here, the second optical path (2) reflects the light vertically incident on the rear metal electrode 180 on the curved surface of the electrode wire bonded to the pad electrode 181, As shown in FIG. The light incident on the transparent substrate 190 in an oblique direction may be reflected again and incident on the perovskite solar cell 130 in a diagonal direction.

Accordingly, the light incident vertically toward the rear metal electrode 180 can be scattered in various directions to increase the probability of re-entering into the perovskite solar cell 130.

The third optical path (3) is an optical path in which light incident vertically toward the side of the electrode wire is reflected and is incident on the perovskite solar cell 130 in an oblique direction. Thus, it is possible to improve the utilization ratio of the short wavelength light in the perovskite absorption layer 132 by the increased optical path while obtaining the antireflection effect.

7 shows various paths in which long wavelength light incident from the front surface of the tandem solar cell is absorbed in the crystalline silicon solar cell 110 in the tandem solar cell.

First, the first optical path (1) is an optical path in which light of a long wavelength is refracted by the transparent electrode structure 160 and is incident on the crystalline silicon solar cell 110 in an oblique direction. That is, by introducing the patterned transparent electrode structure 160 on the front surface of the perovskite solar cell 130, an optical path of a long wavelength vertically incident on the tandem solar cell is changed to an oblique direction to obtain an antireflection effect It is possible to increase the light path and improve the utilization ratio of the long wavelength light in the crystalline silicon solar cell 110.

The second optical path (2) and the third optical path (3) are formed by a transparent substrate (190) having a rear transparent electrode (140) and a rear transparent electrode (140) Reflected path is shown.

First, when light of a long wavelength reaches the rear transparent electrode 140 along the second optical path (2), a part of the light is reflected and re-entered into the crystalline silicon solar cell 110. On the other hand, the light transmitted through the rear transparent electrode 140 is again reflected in a diagonal direction by the transparent substrate 190 and is incident again on the crystalline silicon solar cell 110, and this optical path is reflected by the third optical path (3) .

The rear metal electrode 180 is provided only in a part of the rear surface of the rear transparent electrode 140 in order to allow the light transmitted through the rear transparent electrode 140 to be emitted to the rear surface as in the third optical path (3). Accordingly, light having a long wavelength that is not absorbed by the crystalline silicon solar cell 110 can be emitted to the rear along the third optical path (3), and the light emitted to the rear surface is reflected by the transparent substrate 190, It is possible to re-enter the silicon solar cell 110, and the utilization ratio of the long wavelength light can be improved.

The fourth optical path (4) is an optical path in which light incident vertically toward the front surface of the front metal electrode 170 is reflected on the curved surface of the electrode wire and is incident on the transparent substrate 200 in an oblique direction. Light incident on the transparent substrate 200 in an oblique direction can be reflected again to be incident on the tandem solar cell in a diagonal direction and transmitted through the perovskite solar cell 130 to the crystalline silicon solar cell 110 Can reach.

That is, according to the fourth optical path (4), the light incident vertically toward the electrode wire 172 can be scattered in various directions to increase the probability of re-entering the crystalline silicon solar cell 110.

FIG. 8 shows various paths in which long wavelength light incident from the rear surface of the tandem solar cell is absorbed in the crystalline silicon solar cell 110 in the tandem solar cell.

First, the first optical path (1) is a light path in which light of a long wavelength is refracted by the texture structure introduced on the rear surface of the crystalline silicon solar cell 110 and is incident on the crystalline silicon solar cell 110 in an oblique direction. In other words, by introducing a texture structure on the rear surface of the crystalline silicon solar cell 110, the optical path of a long wavelength vertically incident from the rear surface of the tandem solar cell is changed to diagonal direction, thereby obtaining an antireflection effect, The utilization factor of the long wavelength light in the silicon solar cell 110 can be improved.

The second optical path (2) and the third optical path (3) are paths through which long-wavelength light is reflected by the rear metal electrode 180 in the form of an electrode wire having a cylindrical or elliptical cross-section.

Here, the second optical path (2) is an optical path in which light incident vertically toward the rear metal electrode 180 is reflected on the curved surface of the electrode wire and is incident on the transparent substrate 190 in an oblique direction. The light incident on the transparent substrate 190 in an oblique direction may be reflected again and incident on the crystalline silicon solar cell 110 in an oblique direction.

The third optical path (3) is a light path in which light incident vertically toward the side of the electrode wire is reflected and is incident on the crystalline silicon solar cell 110 in an oblique direction.

Second Example

9 is a cross-sectional view of a tandem solar cell according to a second embodiment of the present invention.

The crystalline silicon solar cell 210 according to the second embodiment may be implemented as a homojunction crystalline silicon solar cell.

More specifically, the crystalline silicon solar cell 210 according to the second embodiment includes a crystalline silicon substrate 211, an emitter layer 212 located on the front surface of the crystalline silicon substrate 211, And a rear front layer 213 in which the rear front layer 213 is located. The front surface of the crystalline silicon substrate 211 is a portion where light in a long wavelength region transmitted through the perovskite solar cell 230 is first incident on the crystalline silicon solar cell 210.

An impurity doping layer having a conductivity type different from that of the crystalline silicon substrate is used for the emitter layer 212. An impurity doping layer having the same conductivity type as that of the crystalline silicon substrate is used for the rear front layer 213, Silicon solar cells can be implemented.

For example, when the crystalline silicon substrate 211 is an n-type single crystal silicon substrate, the emitter layer 212 is a semiconductor layer doped with a p-type impurity, and the rear front layer 213 is a semiconductor layer doped with n-type impurities to be. In this case, the rear front layer 213 may be a p + -type semiconductor layer doped at a higher concentration than the concentration of the p-type impurity doped in the crystalline silicon substrate 211.

As the crystalline silicon substrate 211, a p-type single crystal silicon substrate instead of the n-type single crystal silicon substrate or another crystalline silicon substrate commonly used for the crystalline silicon solar cell 210 may be used. Likewise, the emitter layer 212 and the rear whole layer 213 may also be designed to be doped with an impurity having a suitable conductivity type depending on the conductivity type of the crystalline silicon substrate 211.

A front passivation layer 221 and a rear passivation layer 240 are disposed on the front surface of the emitter layer 212 and the rear surface of the rear front layer 213, respectively. In particular, the front passivation layer 221 may be disposed to cover the defect of the front surface of the emitter layer 212 and at the same time to ensure conductivity for the tunnel junction via the bonding layer 220.

The front passivation layer 221 and the rear passivation layer 240 may comprise at least one dielectric material selected from silicon oxide (SiO _x ), silicon nitride (Si _x N _y ), and silicon oxynitride (SiO _x N _y ) have.

The electric charge generated in the crystalline silicon solar cell 210 is collected in the rear metal electrode 280. At this time, the rear metal electrode 280 is located in a part of the rear surface of the rear passivation layer 240, and contacts the rear surface of the rear front layer 213 through the rear passivation layer 240.

9, the rear metal electrode 280 is not provided on the entire rear surface of the rear passivation layer 240 but is formed on a part of the rear surface of the rear passivation layer 240, Solar light may be incident from the rear surface of the battery 210.

At this time, it is preferable that the rear metal electrode 280 is arranged to occupy 1% to 30% of the entire area of the rear surface of the rear passivation layer 240. If the area occupied by the rear metal electrode 280 is less than 1%, the effect of trapping charges generated in the crystalline silicon solar cell 210 by the rear metal electrode 280 may be insufficient. On the other hand, The area occupied by the rear metal electrode 280 is excessively wide, which may lower the utilization rate of light incident from the rear surface of the crystalline silicon solar cell 210. [

The rear metal electrode 280 includes a pad electrode 281 that contacts a portion of the rear surface of the rear front layer 213. In addition, a grid electrode structure for collecting charges may be formed on the rear surface of the rear front layer 213, and a pad electrode 281 may be provided on a part of the rear surface of the grid electrode structure. An electrode wire 282 is bonded to the rear surface of the pad electrode 281 by soldering to electrically connect neighboring tandem solar cells (cells), and an electrode wire 282 connected to the rear surface of the pad electrode 281 of one cell The first electrode 282 is integrally formed with the electrode wire 272 connected to the front surface of the pad electrode 271 of the neighboring cell. Here, the electrode wire 282 is preferably a wire having a cylindrical or elliptical cross section.

In addition, a texture structure is introduced into the rear surface of the crystalline silicon substrate 211 and the rear front layers 213 and 115 and the rear passivation layer 240, which are sequentially provided on the rear surface of the crystalline silicon substrate 211, The path of light incident vertically through the rear surface of the crystalline silicon solar cell 210 can be changed to an oblique direction. That is, the light scattering effect by the texture structure introduced to the rear surface of the crystalline silicon solar cell 210 can increase the path of light incident from the rear surface of the crystalline silicon solar cell 210.

When the perovskite solar cell 230 is formed on the entire surface of the silicon solar cell 210 by making the front surface of the crystalline silicon substrate 211 flat without introducing a texture structure different from the rear surface, It is possible to prevent the occurrence of defects in the substrate 230.

A bonding layer 220 for electrically connecting the crystalline silicon solar cell 210 and the perovskite solar cell 230 by tunneling is formed on the front surface of the emitter layer 212 of the crystalline silicon solar cell 210 Located.

At this time, the bonding layer 220 may be realized as a multi-layer structure in which an n + type crystalline silicon layer and a p + type crystalline silicon layer are alternately laminated at least once.

The front surface of the bonding layer 220 is positioned with the perovskite solar cell 230. The perovskite solar cell 230 includes an electron transport layer 231 located on the front surface of the bonding layer 220, a perovskite absorption layer 232 located on the front surface of the electron transport layer, And a hole transport layer 233 disposed on the front surface. In addition, the mesoporous layer 231a containing the same or different metal oxide as the electron transport layer 231 may be further provided on the entire surface of the electron transport layer 231.

The electric charges generated in the perovskite solar cell 230 having the above structure are collected in the front transparent electrode 250 and the connection between the front transparent electrode 250 and the external terminal is transmitted through the front metal electrode 270 . Examples of the transparent conductive material for realizing the front transparent electrode 250 include a transparent conductive oxide, a carbonaceous conductive material, a metallic material, and a conductive polymer

Here, the tandem solar cell according to the embodiment of the present invention reduces the reflectance of vertically incident light and changes the incidence direction of light to diagonal direction so as to increase the optical path passing through the tandem solar cell, And a transparent electrode structure 260 patterned to have a nano-sized structure on the front surface or have a grid-like pattern such as a grid or a mesh pattern.

That is, by arranging the patterned transparent electrode structure 260 on the front surface of the front transparent electrode 250, it is possible to reduce the reflectance of the incident light by changing the incident angle of the light vertically incident on the tandem solar cell.

As shown in FIGS. 9 and 10, the transparent electrode structure 260 is provided as a separate layer between the front transparent electrode 250 and the transparent electrode structure 260, and the transparent electrode structure 260 includes a grid, Or patterned in a concavo-convex pattern, the front transparent electrode 250 can be exposed in some areas. 11, the front transparent electrode 250 and the transparent electrode structure 260 may be integrally formed. In this case, after the transparent electrode is deposited, the front transparent electrode 250 and the transparent electrode structure 260 are patterned to a predetermined depth from the front surface, (260) can be formed.

The front metal electrode 270 is provided in a part of the front surface of the front transparent electrode 250. The front metal electrode 270 includes a pad electrode 271 contacting a part of the front surface of the front transparent electrode 250. In addition, a grid electrode structure for collecting charges may be formed on the front surface of the front transparent electrode 250, and a pad electrode 271 may be provided on a part of the front surface of the grid electrode structure. An electrode wire 272 is joined to the front surface of the pad electrode 271 by soldering to electrically connect neighboring tandem solar cells (cells), and an electrode wire 272 connected to the front surface of the pad electrode 271 of one cell The electrode 272 is integrally formed with the electrode wire 282 connected to the rear surface of the pad electrode 281 of the neighboring cell.

Here, the electrode wire 272 is preferably a wire having a cylindrical or elliptical cross section. Accordingly, the light incident vertically toward the electrode wire 272 can be scattered and the probability of re-entering into the tandem solar cell can be increased.

[Manufacturing method of tandem solar cell]

FIG. 12 shows a manufacturing procedure of the tandem solar cell shown in FIG. 2, and FIG. 13 shows a manufacturing procedure of the tandem solar cell shown in FIG.

Preparation phase of crystalline silicon solar cell

12 and 13 (a) show the steps of preparing crystalline silicon substrates 111 and 211 for realizing a crystalline silicon solar cell, FIG. 12 (b) 110, and 210, respectively.

12A, the entire surface of the crystalline silicon substrate 111 is chemically flattened before the i-type amorphous silicon layer and the conductive amorphous silicon layer are formed on the front surface and the rear surface of the crystalline silicon substrate 111, respectively , And introduces a texture structure on the rear side.

13A, the entire surface of the crystalline silicon substrate 211 is chemically flattened before forming the emitter layer and the rear front layer on the front surface and the rear surface of the crystalline silicon substrate 211, Introduces texture structure.

The planarization and texture structure of the crystalline silicon substrate according to Figs. 12 (a) and 13 (a) can be introduced by any one of a wet chemical etching method, a dry chemical etching method, an electrochemical etching method, and a mechanical etching method And is not necessarily limited. For example, a front surface and a back surface of a crystalline silicon substrate are etched in a basic aqueous solution (wet chemical etching method) to introduce a textured structure on both sides, and then a front surface is flattened by selective etching on the entire surface of the silicon substrate, A silicon substrate into which the structure is introduced can be obtained. Selective etching of the entire surface of the silicon substrate can be performed by forming a passivation layer on the back surface and then performing etching or spraying an etchant only on the front surface of the silicon substrate.

Each of the layers sequentially formed from the rear surface of the crystalline silicon substrates 111 and 211 by introducing the texture structure to the rear surfaces of the crystalline silicon substrates 111 and 211 has a texture structure May have a texture structure corresponding to the texture. On the other hand, since the entire surfaces of the crystalline silicon substrates 111 and 211 have undergone the planarization process, the respective layers sequentially formed from the entire surface of the crystalline silicon substrates 111 and 211 can be formed flat. However, if necessary, it may further include a patterning step such as etching an arbitrary layer among a plurality of layers formed on the entire surface of the crystalline silicon substrates 111 and 211 to introduce irregularities.

Next, referring to FIG. 12B, a front i-type amorphous silicon layer 112 and a rear i-type amorphous silicon layer 113 are formed on the front and back surfaces of the crystalline silicon substrate 111, respectively, A first conductive amorphous silicon layer 114 is formed on the entire surface of the amorphous silicon layer 112 and a second conductive amorphous silicon layer 115 is formed on the rear surface of the rear i-

Here, the i-type amorphous silicon layer, the first conductivity type amorphous silicon layer, and the second conductivity type amorphous silicon layer can be deposited by various known methods, and a typical CVD method is Chemical Vapor Deposition (CVD). Examples of the chemical vapor deposition method include atmospheric pressure CVD, reduced pressure CVD, plasma CVD (PECVD), electron cyclotron resonance (ECR) plasma CVD, high temperature CVD, and low temperature CVD. At this time, the i-type amorphous silicon layer may be deposited to a thickness of 2 to 10 nm, and the first conductive amorphous silicon layer and the second conductive amorphous silicon layer may be deposited to a thickness of 10 to 80 nm.

Referring to FIG. 13B, an emitter layer 212 and a rear front layer 213 are formed on the front and rear surfaces of the crystalline silicon substrate 211, respectively.

The emitter layer 212 and the rear front layer 213 may be formed through an implant process wherein the emitter layer 212 is doped with boron as an impurity and the back front layer 213 is doped with phosphorous ). When the emitter layer 212 and the rear whole layer 213 are formed by the implant process, it is preferable to carry out the heat treatment at 700 to 1,200 ° C to activate the impurities. It is also possible to instead implant process through a high temperature diffusion process which uses such as BBr ₃ or POCl ₃ to form the emitter layer 212 and around the rear layer (213).

Referring to FIG. 12C, a rear transparent electrode 140 is formed on the rear surface of the crystalline silicon solar cell 110, and a bonding layer 120 is formed on the front surface.

The bonding layer 120 and the rear transparent electrode 140 may be formed of various transparent conductive materials. Examples of the transparent conductive material for forming the bonding layer 120 and the rear transparent electrode 140 include a transparent conductive oxide, a carbonaceous conductive material, a metallic material, and a conductive polymer.

For example, a transparent conductive oxide such as ITO (Indium Tin Oxide), ICO (Indium Cerium Oxide), Ehsms IWO (Indium Tungsten Oxide)) is used as a transparent conductive material for forming the bonding layer 120 and the rear transparent electrode 140 When used, the bonding layer 120 and the rear transparent electrode 140 may be deposited by sputtering. It is also possible to use an n-type amorphous silicon layer instead of a transparent conductive oxide as the bonding layer 120 by PECVD.

Referring to FIG. 13C, a rear passivation layer 240 is formed on the rear surface of the crystalline silicon solar cell 210, and a bonding layer 220 is formed on the front surface.

At this time, a surface defect of the emitter layer 212 is reduced before the bonding layer 220 is formed, a passivation layer having a thickness of 0.5 to 10 nm is formed on the entire surface of the emitter layer 212 to secure conductivity for tunnel bonding The bonding layer 220 can be formed. For example, the passivation layer may be composed of SiO _x and may be formed by a wet process, ozone treatment, or PECVD. Then, a bonding layer 220 may be formed by sequentially depositing a p + -type crystalline silicon layer and an n + -type crystalline silicon layer having a thickness of 50 to 500 nm on the entire surface of the passivation layer. The back passivation layer 240 may be formed by depositing silicon oxide (SiO _x ), silicon nitride (Si _x N _y ), or silicon oxynitride (SiO _x N _y ) by PECVD.

Referring to FIG. 13D, a pad electrode 281 penetrating the rear passivation layer 240 is formed. The pad electrode 281 may be formed by patterning Ag, Al or Ag-Al paste on the rear surface of the rear passivation layer 240 through screen printing, followed by drying and heat treatment. The pad electrode 281 patterned through the heat treatment may form a contact with the rear front layer 213.

Referring to FIGS. 12 (d) and 12 (e) and 13 (e), perovskite solar cells 130 and 230 are formed on the front surfaces of the bonding layers 120 and 220.

First, mesoporous layers 131a and 231a are formed on the entire surfaces of the electron transfer layers 131 and 231 after the electron transfer layers 131 and 231 are formed on the entire surfaces of the bonding layers 120 and 220. At this time, the electron transport layers 131 and 231 and the mesoporous layers 131a and 231a may be formed of the same metal oxide.

For example, the electron transport layers 131 and 231 may be formed to a thickness of 5 to 100 nm, and the mesoporous layers 131a and 231a may be formed of a TiO ₂ layer having a thickness of 500 nm or less. Perovskite absorbing layers 132 and 232 are formed on the front surfaces of the mesoporous layers 131a and 231a and the mesopores in the mesoporous layers 131a and 231a are filled with the perovskite absorbing layers 132 and 232 A thickness of 100 to 500 nm may be formed. The hole transport layers 133 and 233 may be formed to a thickness of 5 to 100 nm by using a conductive polymer as a front surface of the perovskite absorption layers 132 and 232.

Each of the layers constituting the perovskite solar cells 130 and 230 may be formed through physical vapor deposition, chemical vapor deposition or printing, for example. Here, printing methods include ink jet printing, gravure printing, spray coating, doctor blade, bar coating, gravure coating, brush painting and slot-die coating and the like.

Referring to FIGS. 12 and 13 (f), the crystalline silicon solar cells 110 and 210 and the perovskite solar cells 130 and 230, which are tunnel-bonded via the bonding layers 120 and 220, The front transparent electrodes 150 and 250 and the transparent electrode structures 160 and 260 are formed on the front surfaces of the perovskite solar cells 130 and 230.

Here, the front transparent electrodes 150 and 250 and the transparent electrode structures 160 and 260 may be formed using various transparent conductive materials as well as other layers to which transparent electrodes are applied. In addition, the front transparent electrodes 150 and 250 and the transparent electrode structures 160 and 260 may be formed of the same or different transparent conductive materials.

For example, when a transparent conductive oxide such as ITO (Indium Tin Oxide) is used as the transparent conductive material for forming the front transparent electrodes 150 and 250, the front transparent electrodes 150 and 250 may be deposited by sputtering have.

The method of patterning the transparent electrode structures 160 and 260 on the entire front transparent electrodes 150 and 250 may be appropriately selected in consideration of the pattern shape of the transparent electrode structures 160 and 260 and the number of processes.

For example, the transparent electrode structures 160 and 260 shown in FIGS. 2 and 9 may be formed by depositing the front transparent electrodes 150 and 250 and the transparent electrode structures 160 and 260 as separate layers by sputtering, (Wet or dry) such that a grid-like pattern such as a grid or a mesh pattern is formed by introducing a nanosized structure into the transparent electrode structures 160 and 260 deposited in the form of a single layer. At this time, the front transparent electrodes 150 and 250 may be exposed in the area where the transparent electrode structures 160 and 260 are etched. According to another example, after an appropriate amount of the nano-spherical solution is applied to the entire front transparent electrode 150, the transparent electrode structures 160 and 260 are formed to have a grid or mesh pattern through a self-assembly induction method in which energy such as ultrasonic waves is applied. ) Can be formed.

The transparent electrode structures 160 and 260 shown in FIGS. 3 and 10 are formed to have a concave-convex pattern by controlling the degree of etching of the transparent electrode structure 160. The transparent electrode structures 160 and 260 shown in FIGS. 4 and 11 are integrally formed with the front transparent electrodes 150 and 260. That is, the patterned transparent electrode structures 160 and 260 can be introduced to the front surfaces of the front transparent electrodes 150 and 250 by depositing the front transparent electrodes 150 and 250 and then etching them to a predetermined depth.

12G, a front metal electrode 170 is formed on the front surface of the front transparent electrode 150 and a rear metal electrode 180 is formed on the rear surface of the rear transparent electrode 140. Referring to FIG. In particular, it is preferable that the rear metal electrode 180 is formed only in a part of the rear surface of the rear transparent electrode 140 so that light of a long wavelength which is not absorbed by the crystalline silicon solar cell 110 can be emitted to the rear surface.

Here, the front metal electrode 170 and the rear metal electrode 180 include pad electrodes 171 and 181, and may selectively include a grid electrode (not shown). The front metal electrode 170 and the rear metal electrode 180 including the grid electrode and the pad electrodes 171 and 181 are formed of Ag, Al, or Ag-Al so as to contact the front transparent electrode 150 and the rear transparent electrode 140, respectively. Screen printing the Al paste, and then heat-treating at 100 to 150 ° C.

Referring to FIG. 13 (g), a front metal electrode 270 is formed on the front surface of the front transparent electrode 250 in the same manner as in FIG. 12 (g).

[Tandem Solar Cell Module]

Fig. 14 schematically shows a modular form of the tandem solar cell (cell) according to the present invention. Each of the solar cells is subjected to a modularization step in order to increase the output and protect the solar cell from moisture or external impact.

Accordingly, according to another aspect of the present invention, the tandem solar cell disclosed herein can be modularized by connecting two neighboring tandem solar cells in series using a conductor.

14, neighboring two tandem solar cells C1 and C2 are connected to each other by electrode wires 172 and 182. [ At this time, neighboring two tandem solar cells can be connected to each other by a multi wire tabbing method.

For example, one of the electrode wires 172 and 272 is soldered to the pad electrodes 171 and 271 located on the front surface of the arbitrary tandem solar cell C1 and the other one of the electrode wires 172 and 282 is soldered And soldered to the pad electrodes 181 and 281 located on the rear surface of the other tandem solar cell C2.

An electrode wire of Cu, Ag, Ni or Al coated with solder material (Pb, Sn, SnIn, SnBi, SnPb, Sn, SnCuAg or SnCu) may be used as a conductor for connecting two neighboring tandem solar cells in series have. The electrode wires 172 and 182 may be attached on the pad electrodes 171 and 181 through various methods such as soldering.

At this time, the electrode wires 172 and 182 are preferably wire-shaped having a cylindrical or elliptical cross section. Accordingly, the light incident vertically toward the electrode wires 172 and 182 is scattered to increase the probability of re-entering the tandem solar cell, thereby improving the photoelectric conversion efficiency.

5, the front transparent substrate 190 and the rear transparent substrate 200 are bonded to each other with gaps 195 and 205, respectively, on the front and back surfaces of the tandem solar cell module in which a plurality of cells are electrically connected to each other, . At this time, the gaps 195 and 205 may be seal layers filled with an encapsulant such as a sealant. According to another example, a module in which an air layer filled with a gas such as air is not filled in the gaps 195 and 205 between the tandem solar cell, the front transparent substrate 190 and the rear transparent substrate 200, Can be provided.

Here, as the front transparent substrate 190 and the rear transparent substrate 200, a glass substrate, a transparent polymer substrate, or the like may be used. At this time, the corner portions of the tandem solar cell module can be sealed using the sealant 195, 205 and another sealing member.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the scope of the invention is not limited to the disclosed exemplary embodiments. It is obvious that a transformation can be made. Although the embodiments of the present invention have been described in detail above, the effects of the present invention are not explicitly described and described, but it is needless to say that the effects that can be predicted by the configurations should also be recognized.

Claims (19)

A junction layer located on a flat front side of the crystalline silicon solar cell;
A perovskite solar cell positioned on the front surface of the bonding layer;
A front transparent electrode disposed on a front surface of the perovskite solar cell; And
A transparent electrode structure disposed on a front surface of the front transparent electrode and including patterned transparent electrodes;
/ RTI >
Tandem solar cell.
The method according to claim 1,
The transparent electrode structure may have a nanostructure, a concavo-convex pattern or a grid pattern,
Tandem solar cell.
The method according to claim 1,
Wherein the front transparent electrode and the transparent electrode structure are integrally formed,
Tandem solar cell.
The method according to claim 1,
In the crystalline silicon solar cell,
A crystalline silicon substrate having a textured structure on its back surface;
A front i-type amorphous silicon layer and a rear i-type amorphous silicon layer disposed on front and rear surfaces of the crystalline silicon substrate, respectively;
A first conductive amorphous silicon layer located on a front surface of the front i-type amorphous silicon layer; And
A second conductive amorphous silicon layer located on a rear surface of the rear i-type amorphous silicon layer;
/ RTI >
Tandem solar cell.
5. The method of claim 4,
The second conductive amorphous silicon layer is disposed on the front surface of the rear transparent electrode.
Tandem solar cell.
6. The method of claim 5,
Wherein a rear metal electrode is located in a part of the rear surface of the rear transparent electrode,
Tandem solar cell.
The method according to claim 1,
In the crystalline silicon solar cell,
A crystalline silicon substrate having a textured structure on its back surface;
An emitter layer located on the front surface of the crystalline silicon substrate; And
A rear front layer positioned on the rear surface of the crystalline silicon substrate;
/ RTI >
Tandem solar cell.
8. The method of claim 7,
Wherein the emitter layer is an impurity doping layer having a conductivity type different from that of the crystalline silicon substrate and the rear whole layer is an impurity doping layer having the same conductivity type as the crystalline silicon substrate,
Tandem solar cell.
8. The method of claim 7,
The back front layer is located on the front surface of the rear passivation layer.
Tandem solar cell.
10. The method of claim 9,
A rear metal electrode is located in a part of the rear surface of the rear passivation layer,
Wherein the back metal electrode contacts the rear surface of the rear front layer through the rear passivation layer,
Tandem solar cell.
The method according to claim 1,
In the perovskite solar cell,
An electron transport layer located on the front surface of the bonding layer;
A perovskite absorption layer positioned on the front surface of the electron transport layer; And
A hole transport layer located on the front surface of the perovskite absorption layer;
/ RTI >
Tandem solar cell.
12. The method of claim 11,
Further comprising a mesoporous layer on the front surface of the electron transport layer,
Tandem solar cell.
A junction layer located on a flat front side of the crystalline silicon solar cell;
A perovskite solar cell positioned on the front surface of the bonding layer;
A front transparent electrode disposed on a front surface of the perovskite solar cell;
A transparent electrode structure disposed on a front surface of the front transparent electrode and including patterned transparent electrodes;
A front metal electrode located on a front surface of the transparent electrode structure; And
A rear metal electrode positioned on the rear surface of the crystalline silicon solar cell;
And a plurality of tandem solar cells,
The front metal electrode and the rear metal electrode of the neighboring two tandem solar cells of the plurality of tandem solar cells are electrically connected to each other by electrode wires,
A plurality of tandem solar cells each having a front transparent substrate and a rear transparent substrate,
Tandem solar cell module.
14. The method of claim 13,
A plurality of tandem solar cells each including a plurality of tandem solar cells, a plurality of tandem solar cells,
Tandem solar cell module.
14. The method of claim 13,
Wherein an air layer filled with gas is present between the front surface of the plurality of tandem solar cells and the front transparent substrate, or between the rear surface of the plurality of tandem solar cells and the rear transparent substrate,
Tandem solar cell module.
14. The method of claim 13,
Wherein both sides of the tandem solar cell module are sealed by an encapsulating material,
Tandem solar cell module.
Forming a crystalline silicon solar cell from a crystalline silicon substrate;
Forming a bonding layer on the flat top surface of the crystalline silicon solar cell;
Forming a perovskite solar cell on the front surface of the bonding layer;
Forming a front transparent electrode on the front surface of the perovskite solar cell; And
Patterning the transparent electrode structure on the front surface of the front transparent electrode;
/ RTI >
Method of manufacturing tandem solar cell.
18. The method of claim 17,
Wherein the transparent electrode structure is patterned to have a concavo-convex pattern or a grid pattern,
Method of manufacturing tandem solar cell.
18. The method of claim 17,
And forming the transparent electrode structure by etching the front transparent electrode,
Method of manufacturing tandem solar cell.

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