KR102543003B1 - Solar cell module and manufacturing method for the same - Google Patents

Abstract

The present invention relates to a solar cell module capable of uniform unit film deposition and excellent unit film and cell characteristics by a low-temperature process, and a method for manufacturing the solar cell module capable of high productivity.
According to the solar cell module of the present invention, a plurality of tandem solar cells including an upper solar cell including a perovskite absorbing layer and a lower solar cell positioned below the upper solar cell; bus bar electrodes positioned on the upper and lower solar cells; By providing a tandem solar cell module including an electrically conductive adhesive for interconnecting the bus bar electrodes of the plurality of tandem solar cells, it is possible to obtain effects of excellent uniformity, excellent photoelectric conversion efficiency and excellent productivity.

Description

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

The present invention relates to a solar cell module capable of uniform unit film deposition and excellent unit film and cell characteristics by a low-temperature process, and a method for manufacturing the solar cell module capable of high productivity.

A solar cell is a type of energy conversion device that converts sunlight energy into electrical energy, and is currently one of the most commercialized alternative energy technologies.

Among them, a crystalline silicon (c-Si) solar cell is a representative single junction solar cell and is currently widely used as a commercial solar cell.

However, due to the low photoelectric conversion efficiency of crystalline silicon solar cells, development of tandem solar cells constituting one solar cell by connecting single junction solar cells including absorbers having different band gaps has been actively progressed.

1 schematically shows a cross section of a 2-terminal tandem solar cell, which is a general type among tandem solar cells.

Referring to FIG. 1 , a single junction solar cell including an absorber layer having a relatively large band gap and a single junction solar cell including an absorber layer having a relatively small band gap are tunnel-junctioned through a bonding layer.

Among them, a perovskite/crystalline silicon tandem solar cell using a single junction solar cell including an absorber layer with a relatively large bandgap as a perovskite solar cell achieves a high photoelectric efficiency of 30% or more. It is getting a lot of attention.

In such a tandem solar cell, a texture structure is typically formed on the surface of a crystalline silicon substrate to reduce reflectance of incident light. However, when such a texture structure is formed under the tandem solar cell, there is a problem in that the perovskite solar cell is not uniformly deposited.

Because the texture structure usually has a size of several to several tens of μm, while the unit film has a thickness of about tens to hundreds of nm, each unit film is a conformal growth that grows while maintaining the substrate or unit film shape below it. will do At this time, if the substrate or the film below has a texture, it is very difficult to uniformly form a unit film at the peak portion of the texture due to the Gibbs-Thomson effect.

Therefore, conventionally, a substrate having a small size had to be used for uniform deposition of a perovskite solar cell on a textured substrate. However, in this case, uniform deposition may be possible, but there is a problem in that productivity is significantly lowered.

On the other hand, a commercial solar cell is used as a solar cell module by electrically connecting a plurality of solar cells in series or parallel and going through a packaging process.

This is because the electromotive force generated by each single solar cell is not sufficient for commercial use.

In the case of a conventional crystalline silicon solar cell (c-Si) solar cell, a bus bar and a ribbon have been electrically bonded through soldering in the tabbing step before the lamination step.

Recently, however, perovskite solar cells or tandem solar cells including the perovskite solar cells have been actively developed and commercialized, as described above, in order to improve the low efficiency of conventional crystalline silicon solar cells.

Such a perovskite solar cell or tandem solar cell includes a perovskite absorbing layer, and the perovskite absorbing layer has a disadvantage in that it is very vulnerable to heat and moisture.

Therefore, a solar cell including a perovskite absorber layer must avoid a high-temperature process not only in a solar cell process but also in a subsequent module process in order to prevent decomposition of the perovskite absorber layer due to heat.

In particular, in an interconnection process such as a tabbing step included in a conventional crystalline silicon solar cell module manufacturing method, bus bar electrodes of each solar cell are connected to each other through a method such as soldering.

However, when the soldering method is used in a module manufacturing method of a single solar cell or tandem solar cell including a perovskite absorber layer, there is a problem in that the possibility of thermal decomposition or degradation of the perovskite absorber layer increases.

Therefore, in manufacturing a solar cell module using a perovskite solar cell or a tandem solar cell including the same, a unit film having excellent uniformity can be obtained, productivity is high, and destruction of the perovskite absorber layer can be prevented by a high-temperature process. It is necessary to develop a solar cell module and a method for manufacturing the same.

An object of the present invention is to provide a solar cell module made of a unit film having excellent uniformity in a solar cell module composed of a plurality of solar cells.

In addition, in a solar cell module composed of a plurality of solar cells, the present invention aims to provide a solar cell module in which degradation of efficiency does not occur by avoiding destruction or deterioration of the perovskite absorber layer by a high-temperature process. do.

In addition, the present invention, in order to provide the solar cell module as described above, is to first provide a method of manufacturing a solar cell module in which a uniform unit film can be manufactured and productivity is greatly improved in the manufacturing method of a solar cell. do.

In addition, the present invention is intended to provide a method for manufacturing a solar cell module capable of securing electrical connections between solar cells constituting the solar cell module while preventing destruction or deterioration of the perovskite absorbing layer.

According to the tandem solar cell module of the present invention, which does not undergo a high-temperature module process, there is no damage to the perovskite absorbing layer, and the uniformity and productivity of the unit films constituting the upper solar cell are excellent, the upper part including the perovskite absorbing layer a plurality of tandem solar cells including a solar cell and a lower solar cell positioned below the upper solar cell; bus bar electrodes positioned on the upper and lower solar cells; A tandem solar cell module including an electrically conductive adhesive interconnecting bus bar electrodes of the plurality of tandem solar cells may be provided.

Preferably, a tandem solar cell module including a wiring member positioned between the electrically conductive adhesive and the bus bar electrode may be provided.

Alternatively, a tandem solar cell module characterized in that the bus bar electrodes directly contact each other may be provided.

Preferably, the lower cell is a crystalline silicon solar cell; a tandem solar cell module may be provided.

At this time, the crystalline silicon solar cell is a heterojunction solar cell; a tandem solar cell module characterized in that it can be provided.

Preferably, the electrically conductive adhesive includes at least one adhesive polymer selected from the group consisting of epoxy, polyurethane, silicone, polyimide, phenol, and polyester; A tandem solar cell module including dispersed metal particles of micro, meso, or nano size may be provided.

On the other hand, a eutectic mixture located between the bus bar electrode and the wiring member; A solar cell module comprising a may be provided.

In addition, according to the method for manufacturing a tandem solar cell module according to an embodiment of the present invention capable of securing uniformity and productivity of unit films constituting an upper solar cell including a perovskite absorbing layer, a lower solar cell on a substrate positioning lower solar cell unit films constituting; placing an intermediate layer on the lower solar cell; Positioning unit films of an upper solar cell constituting an upper solar cell including a perovskite absorbing layer on the intermediate layer; including, in any step among the steps of positioning unit films constituting the upper solar cell A method for manufacturing a tandem solar cell module further comprising a scribing step of dividing the substrate into arbitrary mini-cell sizes may be provided.

Preferably, the scribing step is located between arbitrary steps among the steps of forming an electron transport layer, a perovskite absorbing layer, and a hole transport layer among the unit films of the upper solar cell; characterized in that A method of manufacturing a tandem solar cell module may be provided.

In addition, according to a method for manufacturing a tandem solar cell module according to another embodiment of the present invention capable of securing uniformity and productivity of unit films constituting an upper solar cell including a perovskite absorbing layer, a lower solar cell on a substrate positioning lower solar cell unit films constituting; placing an intermediate layer on the lower solar cell; positioning upper solar cell unit films constituting an upper solar cell including a perovskite absorbing layer on the intermediate layer; After locating the upper solar cell, a scribing step of dividing the substrate into arbitrary mini-cell sizes is included, and a mask is placed between the mini-cells on the substrate at any step among the steps of arranging the unit films constituting the upper solar cell. A method of manufacturing a tandem solar cell module further comprising a; masking step of forming a may be provided.

Preferably, the masking step is located between arbitrary steps among the steps of forming an electron transport layer, a perovskite absorbing layer, and a hole transport layer among the unit films of the upper solar cell; Characterized in that A method of manufacturing a tandem solar cell module may be provided.

According to the present invention, deterioration in photoelectric conversion efficiency of a tandem solar cell module including a perovskite solar cell can be prevented by preventing deterioration and destruction of the perovskite absorption layer in the solar cell module.

In addition, the efficiency of the tandem solar cell module can be increased by securing the uniformity of the unit film.

Furthermore, in the present invention, in the modularization of solar cells, the yield of the module can be secured by securing the alignment and electrical connection of each unit solar cell, and furthermore, the charge carriers generated in the solar cell can be efficiently collected. A decrease in the effective cross-sectional area can be prevented, thereby avoiding a decrease in photoelectric conversion efficiency.

Meanwhile, in the method for manufacturing a tandem solar cell module of the present invention, not only can a uniform unit film be manufactured, but also a greatly improved effect of productivity compared to the conventional unit cell process can be obtained.

1 is a schematic diagram schematically showing a general tandem solar cell.
2 shows an embodiment of forming a solar cell constituting the module in the tandem solar cell module including the perovskite absorbing layer of the present invention.
3 shows another embodiment of forming a solar cell constituting the module in the tandem solar cell module including the perovskite absorbing layer of the present invention.
4 is a cross-sectional view in which a mask is formed at a boundary between mini cells for module formation in a parent substrate of a tandem solar cell module.
5 illustrates one embodiment of a cross-section of a solar cell module applied to the solar cell module of the present invention.
FIG. 6 is a perspective view schematically illustrating a first solar cell and a second solar cell included in the solar cell module 100 shown in FIG. 5 and connected by a wiring member (eg, a ribbon).
7 is a cross-sectional view illustrating a bonding relationship between a wiring member (eg, a ribbon) and a solar cell.
8 is a cross-sectional view illustrating an example in which two adjacent solar cells among a plurality of solar cells are directly connected without a wiring member.

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

The present invention is not limited to the embodiments disclosed below and can be implemented in various different forms, but only the present embodiments make the disclosure of the present invention complete and the scope of the invention completely covered by those skilled in the art. It is provided to inform you.

In order to clearly describe the present invention, parts irrelevant to the description are omitted, and the same reference numerals are assigned to the same or similar components throughout the specification. In addition, some embodiments of the present invention are described in detail with reference to exemplary drawings. In adding reference numerals to components of each drawing, the same components may have the same numerals as much as possible even if they are displayed on different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known configuration or function may obscure the gist of the present invention, the detailed description may be omitted.

In describing the components of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are only used to distinguish the component from other components, and the nature, sequence, order, or number of the corresponding component is not limited by the term. When an element is described as being “connected,” “coupled to,” or “connected” to another element, that element is or may be directly connected to that other element, but intervenes between each element. It will be understood that may be "interposed", or each component may be "connected", "coupled" or "connected" through other components.

In addition, in implementing the present invention, components may be subdivided for convenience of explanation, but these components may be implemented in one device or module, or one component may be implemented in a plurality of devices or modules. It may be implemented by dividing into .

< No. 1 Example >

2 shows a first embodiment of forming a solar cell constituting a tandem solar cell module including a perovskite absorbing layer of the present invention.

First, the tandem solar cell in the present invention includes a lower solar cell and an upper solar cell. At this time, the lower solar cell is characterized in that the band gap is smaller than that of the upper solar cell. In the tandem solar cell in FIG. 2, a crystalline silicon solar cell is exemplified as the lower solar cell, but the lower solar cell of the present invention is sufficient as long as it has a smaller band gap than the upper solar cell, and is necessarily limited to crystalline silicon solar cells. It is not.

As shown in FIG. 2, the substrate is first textured using a crystalline silicon substrate as a starting material.

More specifically, the crystalline silicon solar cell in the tandem solar cell according to the present invention may also have irregularities by texturing on the first and/or second surfaces of the silicon substrate to prevent reflection. For example, the irregularities may be composed of specific crystal planes. For example, it may have an approximate pyramidal shape formed by four outer surfaces that are {111} surfaces. This is because silicon has a face-centered cubic lattice (fcc) with a diamond cubic crystal structure, and the {111} plane is the most stable as a dense plane when the lattice structure is a face-centered cubic structure.

In this way, when irregularities are formed on the surface of the substrate by texturing, reflection of light incident on the semiconductor substrate can be prevented, and light loss can be effectively reduced.

Next, the crystalline silicon substrate may be doped with a first or second conductivity type dopant, which is a base dopant, at a low doping concentration to form a crystalline semiconductor having a first or second conductivity type. For example, the substrate may be composed of single-crystal or poly-crystal semiconductor (eg, single-crystal or poly-crystal silicon).

At this time, in the case of the crystalline silicon solar cell 110 exemplified as the lower solar cell in the present invention, it may be implemented as a hetero-junction silicon solar cell or a homo-junction silicon solar cell.

For example, as shown in FIG. 2 , the silicon solar cell in the present invention may be implemented as a homo-junction crystalline silicon solar cell. For example, in the case of a homojunction crystalline silicon solar cell having a front emitter layer and a back surface field layer, an impurity doped layer having a different conductivity type from that of the crystalline silicon substrate is used as the emitter layer, and as the back surface field A homojunction crystalline silicon solar cell may be realized by using an impurity-doped layer having the same conductivity as that of the crystalline silicon substrate.

Meanwhile, in FIG. 2, it is illustrated that the back surface layer is formed first and then the front emitter layer is formed, but it is not necessarily limited thereto. Unlike this, in the present invention, the front emitter layer may be formed first, and then the back surface layer may be formed.

Alternatively, the silicon solar cell in the present invention may be implemented as a hetero-junction crystalline silicon solar cell.

More specifically, in the case of a heterojunction silicon solar cell, the crystalline silicon solar cell is a crystalline silicon substrate having a texture structure on the first surface and / or the second surface, respectively located on the first surface and the second surface of the crystalline silicon substrate a first passivation layer and a second passivation layer; a first conductivity type region on the first passivation layer; and a second conductivity type region positioned on the second passivation layer. In this case, the first conductivity type region may be a back surface electric layer or an emitter layer, and the second conductivity type region may be an emitter layer or a back surface electric layer because it has a conductivity type opposite to that of the first conductivity type region.

Next, an intermediate layer (or tunnel junction layer) is positioned on the emitter layer (eg, contact), and a lower electrode electrically connected thereto is positioned (eg, contact) on the back surface layer.

However, in the present invention, although the emitter layer is described and shown (FIG. 2) as being located with the intermediate layer, it is not necessarily limited thereto. As described above, a back surface field (BSF) may be located with an intermediate layer.

First, the lower electrode may further include a lower electrode transparent electrode layer positioned between the back surface layer and the metal electrode layer of the lower electrode.

Here, the lower electrode transparent electrode layer may be entirely formed (eg, contacted) on the back surface layer. Being formed as a whole may include not only covering the entire back surface layer without an empty space or an empty area, but also a case where a part of the layer is inevitably not formed.

In this way, when the lower electrode transparent electrode layer is entirely formed on the back surface layer layer, carriers can easily reach the metal electrode layer of the lower electrode through the lower electrode transparent layer layer, thereby reducing resistance in the horizontal direction.

In particular, if the back surface layer is made of amorphous silicon, etc., the crystallinity of the back surface layer is relatively low, so the mobility of carriers may be low. to lower the resistance.

Next, a lower electrode metal electrode is positioned on the lower electrode transparent electrode layer. The lower electrode metal electrode layer may be formed after fabrication of the lower solar cell, or may be formed together with the upper electrode metal electrode layer after fabrication of the upper solar cell (see FIG. 2 ).

In this case, the lower electrode metal electrode layer may include a metal and a crosslinking resin. The lower electrode metal electrode layer may include metal to improve characteristics such as carrier collection efficiency and resistance reduction. As described above, since the lower electrode metal electrode layer contains metal and may interfere with light incidence, it may have a certain pattern to minimize shading loss. As a result, light can be incident to the portion where the lower electrode metal electrode layer is not formed.

Next, an intermediate layer is positioned on the emitter layer.

The intermediate layer in the tandem solar cell of the present invention uses a transparent conductive oxide, a carbonaceous conductive material, or a metallic material so that long-wavelength light penetrating the upper solar cell can be incident to the lower solar cell without transmission loss.

Specifically, as the transparent conductive oxide, ITO (Indium Tin Oxide), IWO (Indium Tungsten Oxide), ZITO (Zinc Indium Tin Oxide), ZIO (Zinc Indium Oxide), ZTO (Zinc Tin Oxide), GITO (Gallium Indium Tin Oxide) , GIO (Gallium Indium Oxide), GZO (Gallium Zinc Oxide), AZO (Aluminum doped Zinc Oxide), FTO (Fluorine Tin Oxide) or ZnO were used.

Above the middle layer of the present invention, an upper solar cell is located.

When the upper solar cell in the present invention is a perovskite solar cell, a second conductivity-type charge transport layer (or transport layer) positioned on the lower solar cell; a perovskite absorption layer positioned on the second conductivity type charge transport layer; a first conductivity-type charge transport layer positioned on the perovskite absorption layer 132; and an upper electrode layer positioned on the first conductivity type charge transport layer.

As a non-limiting example, when the crystalline silicon substrate is an n-type single-crystal silicon substrate, the first conductivity-type region acts as an emitter layer of a p-type high-concentration amorphous silicon (p+-a-Si:H) layer different from the substrate and The second conductivity type region may be a back surface field (BSF) layer of an n-type high-concentration amorphous silicon (n ⁺ -a-Si:H) layer.

At this time, the second conductivity type charge transport layer in the first solar cell is an n-type electron transport layer identical to the second conductivity type region, and the first conductivity type charge transport layer positioned on the perovskite absorption layer 132 is It becomes the same p-type hole transport layer 133 as the first conductivity type region 114 . The second solar cell of this arrangement becomes a perovskite solar cell, and among them, corresponds to a perovskite solar cell having a normal stacked structure.

Unlike the previous second solar cell, the first solar cell in the present invention is a unit process for forming the first to second conductivity type charge transport layer (or transport layer) of the first solar cell. It is manufactured after dividing the substrate before the process.

In the division of the substrate in the present invention, since the substrate used in the tandem solar cell in the present invention is a crystalline silicon substrate, a scribe process widely used in the semiconductor field can be adopted.

In general, a scribing process refers to a process of making grooves on a surface of a wafer with a diamond cutter, a laser, or the like, in order to cut the wafer into multiple chips.

Therefore, in the present invention, as a method for increasing the photoelectric conversion efficiency of a solar cell, a standardized solar cell, for example, a solar cell using a pseudo square type semiconductor substrate is divided into several through the scribing process described above. to make a small solar cell (hereinafter referred to as a mini cell). Thereafter, the solar cell module of the present invention is manufactured by collecting the small solar cells and electrically connecting them directly or indirectly to each other.

First, as illustrated in FIG. 2 , in the first solar cell of the present invention, the electron transport layer may be formed after dividing the substrate before forming the electron transport layer. Therefore, the process in the following embodiment is performed on each divided unit substrate (ie, mini cell) rather than on a so-called mother substrate.

The electron transport layer in the present invention may be formed of an electron conductive organic material layer, an electron conductive inorganic material layer, or a layer including silicon (Si).

The electron conductive organic material may be an organic material used as an n-type semiconductor in a conventional solar cell. As a specific and non-limiting example, the electron conductive organic material is fullerene (C ₆₀ , C ₇₀ , C ₇₄ , C ₇₆ , C ₇₈ , C ₈₂ , C ₉₅ ), PCBM ([6,6]-phenyl-C61butyric acid methyl ester )) and fullerene-derivatives including C71-PCBM, C84-PCBM, PC70BM ([6,6]-phenyl C70-butyric acid methyl ester), PBI (polybenzimidazole), PTCBI (3,4, 9,10-perylenetetracarboxylic bisbenzimidazole), F4-TCNQ (tetra urorotetracyanoquinodimethane), or a mixture thereof.

The electron-conductive inorganic material may be a metal oxide commonly used for electron transport in a conventional quantum dot-based solar cell or dye-sensitized solar cell. As a specific and non-limiting example, metal oxides include Ti oxide, Zn oxide, In oxide, Sn oxide, W oxide, Nb oxide, Mo oxide, Mg oxide, Ba oxide, Zr oxide, Sr oxide, Yr oxide, La oxide, One or more materials selected from V oxide, Al oxide, Y oxide, Sc oxide, Sm oxide, Ga oxide, In oxide and SrTi oxide may be mentioned, and a mixture thereof or a composite thereof may be mentioned. .

On the other hand, the electron transport layer made of a layer containing silicon (Si), more specifically, amorphous silicon (n-a-Si), amorphous silicon oxide (n-a-SiO), amorphous silicon nitride (n-a-SiN), amorphous silicon carbide ( n-a-SiC), amorphous silicon oxynitride (n-a-SiON), amorphous silicon carbonitride (n-a-SiCN), amorphous silicon germanium (n-a-SiGe), microcrystalline silicon (n-uc-Si), microcrystalline silicon oxide ( n-uc-SiO), microcrystalline silicon carbide (n-uc-SiC), microcrystalline silicon nitride (n-uc-SiN), microcrystalline silicon germanium (n-uc-SiGe) containing one or more made of material

Next, a perovskite absorbing layer is positioned on the electron transport layer.

The perovskite absorption layer in the present invention can use all of the currently widely used so-called methylamminium (MA)-based or formamidinium (FA)-based perovskite compounds.

First, considering the band gap characteristics, MAPbI ₃ , which is a representative perovskite compound of the MA (Methylamminium) system having a band gap of about 1.55 ~ 1.6 eV, has a band gap of about 1.45 eV (Formamidinium) of the FA (Formamidinium) system. Since it has a larger band gap than MAPbI ₃ , which is a typical perovskite compound, it has the advantage of being able to better absorb short-wavelength light, which is more advantageous.

However, the FA-based perovskite compound also has a unique advantage in that it has excellent high-temperature stability compared to the MA-based perovskite compound. In addition, recently, it was confirmed that the band gap of the perovskite compound is increased when Br is doped into the FA-based perovskite compound. It was also confirmed that the addition of Cs can suppress the formation of unwanted delta (δ) phase FA compounds.

Therefore, in the present invention, when the FA (Formamidinium) component is used as the perovskite absorbing layer, FA _{1- x} Cs _x PbBr _y I _{3 -y} is more preferable (where 0 = x ≤= 1, 0 ≤ = y ≤= 3).

The addition of Br can increase the band gap of the FA-based perovskite absorber layer to a similar extent to that of the conventional MA-based perovskite absorber layer. When the band gap energy is increased to a high range, the perovskite layer with a high band gap absorbs short-wavelength light compared to conventional silicon solar cells, thereby reducing the thermal loss caused by the difference between photon energy and the band gap, resulting in high voltage. can cause As a result, the efficiency of the solar cell is eventually increased.

A hole transport layer is positioned on the perovskite absorbing layer.

The hole transport layer applicable in the present invention may be formed of a layer including a hole conductive organic material layer, a hole conductive metal oxide, or silicon (Si).

The hole-conducting organic material may be any organic hole-transport material commonly used for hole transport in a conventional dye-sensitized solar cell or organic solar cell. As a specific and non-limiting example, the electron conductive organic material is polyaniline, polypyrrole, polythiophene, poly-3,4-ethylenedioxythiophene-polystyrenesulfonate (PEDOT-PSS), poly-[bis(4-phenyl) (2,4,6-trimethylphenyl)amine] (PTAA), polyaniline-camphorsulfonic acid (PANI-CSA), pentacene, coumarin 6, 3-(2-benzothiazolyl)-7-( diethylamino)coumarin), ZnPC (zinc phthalocyanine), CuPC (copper phthalocyanine), TiOPC (titanium oxide phthalocyanine), Spiro-MeOTAD (2,2',7,7'-tetrakis (N,N-p-dimethoxyphenylamino)- 9,9 '-spirobifluorene), F16CuPC (copper(II) 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro-29H,31H-phthalocyanine ), SubPc (boron subphthalocyanine chloride) and N3 (cis-di (thiocyanato) -bis (2,2'-bipyridyl-4,4'-dicarboxylic acid) -ruthenium (II)), one or more substances selected from can include

Meanwhile, metal oxides include Ni oxide, Mo oxide, and V oxide. In this case, the hole transport layer may further include an n-type or p-type dopant as needed.

The hole transport layer containing silicon (Si) in the present invention is, more specifically, amorphous silicon (p-a-Si), amorphous silicon oxide (p-a-SiO), amorphous silicon nitride (p-a-SiN), amorphous silicon carbide (p-a -SiC), amorphous silicon oxynitride (p-a-SiON), amorphous silicon carbonitride (p-a-SiCN), amorphous silicon germanium (p-a-SiGe), microcrystalline silicon (p-uc-Si), microcrystalline silicon oxide (p -uc-SiO), microcrystalline silicon carbide (p-uc-SiC), microcrystalline silicon nitride (p-uc-SiN), microcrystalline silicon germanium (p-uc-SiGe), or a material containing more than one made up of

Next, an upper electrode is positioned on the hole transport layer in the present invention.

At this time, the upper electrode first includes an upper electrode transparent electrode layer. The upper electrode transparent electrode layer is formed on the entire upper surface of the perovskite solar cell and serves to collect electric charges generated in the perovskite solar cell.

The upper electrode transparent electrode layer may be implemented with various transparent conductive materials. Transparent conductive oxides that can be used as the transparent electrode layer of the upper electrode or lower electrode include ITO (Indium Tin Oxide), IWO (Indium Tungsten Oxide), ZITO (Zinc Indium Tin Oxide), ZIO (Zinc Indium Oxide), ZTO (Zinc Tin Oxide), Gallium Indium Tin Oxide (GITO), Gallium Indium Oxide (GIO), Gallium Zinc Oxide (GZO), Aluminum doped Zinc Oxide (AZO), Fluorine Tin Oxide (FTO), or ZnO may be used.

Next, the upper electrode metal electrode layer is positioned on the upper electrode transparent electrode layer and is disposed in a partial region of the upper electrode transparent electrode. Also, as shown in FIG. 2 , the lower electrode metal electrode layer may be formed simultaneously with the upper electrode metal electrode layer.

The metal electrode layer of the upper electrode may be prepared by selectively applying a paste that does not contain a glass frit and then firing at a low temperature. Here, the electrode paste for the metal electrode layer of the upper electrode may contain metal particles and an organic material that is a binder for low-temperature firing, and the electrode paste for the upper electrode does not include a glass frit. In particular, the process temperature of the upper electrode metal electrode may be 250 °C or less, more specifically, 100 to 200 °C. This is because the tandem solar cell in the present invention includes a perovskite absorbing layer, and the perovskite absorbing layer is very vulnerable to heat and can be decomposed or destroyed by heating.

The tandem solar cell and module according to Example 1 of the present invention has an effect of greatly improving productivity while securing the same level of quality as the unit film compared to the conventional method for manufacturing the tandem solar cell and module.

This is because the unit films of the electron transport layer, the perovskite absorber layer, and the hole transport layer constituting the perovskite solar cell are formed on the textured crystalline silicon solar cell while having conformal growth or coating characteristics. This is because the thickness of the unit films is very thin compared to the height of the texture in the substrate or lower films, and furthermore, because the unit films are mainly formed by a solution process or the like.

However, the tandem solar cell and module of the present invention can greatly improve productivity compared to the existing process using a mini cell by using the crystalline silicon substrate as a mother substrate up to the unit film of the second solar cell below. In addition, from the unit film process of the perovskite solar cell, the first solar cell on the upper side, the unit film is divided into mini cells by the scribing process from the desired step to form a unit film, thereby securing the advantage of securing uniform unit film characteristics at the same time. can

<Example 2>

3 shows another embodiment of forming a solar cell constituting a tandem solar cell module including a perovskite absorbing layer according to the present invention.

When comparing FIG. 3 with FIG. 2, the difference lies in which step the scribing process is performed.

Specifically, in Example 1 of FIG. 2 , the scribing process is performed among the unit film processes of the perovskite solar cell, which is the first solar cell. In contrast, in Example 2 of FIG. 3 , a scribing process is performed after forming all tandem solar cells including the first solar cell.

Therefore, Example 2 shown in FIG. 3 has an advantage in that the productivity of the tandem solar cell and module is further increased compared to Example 1 shown in FIG. 2 . However, the unit films of the tandem solar cell (particularly the perovskite solar cell) according to Example 2 of FIG. 3 may have reduced uniformity compared to the prior art or Example 1.

In the present invention, in order to secure the uniformity of the unit films constituting the perovskite solar cell in Example 2, as shown in FIG. 4, before forming the perovskite solar cell on the top of the tandem solar cell A mask is formed at the boundary of the mini-cells for module formation in the mother substrate.

The step of forming the mask may be added as needed between the steps of depositing the intermediate layer or the hole transport layer among the manufacturing processes of Example 2 of FIG. 3 . For each unit film process constituting the perovskite solar cell, as described in detail in Example 1 above, solution processes are usually mainly used, but thin film processes may also be used if necessary. Therefore, the mask forming step in the present invention, like the scribing process in Example 1, is located before the process in which uniformity is the most difficult to secure among the unit films of the perovskite solar cell, thereby ensuring uniformity and productivity at the same time. possible.

Meanwhile, the process of forming the mask according to the second embodiment of the present invention can greatly reduce lead time, which is a process time per unit process, as well as the number of processes compared to the scribing process.

For example, if n mini-cells are formed on one mother substrate through a scribing process, then the unit process is performed n times on each of several mini-cells, and n mini-cells are separated on the mother substrate through a mask. After performing the unit process n times, there is a large difference in the process time of the corresponding unit process.

If n unit film processes are performed after forming n mini cells through the scribing process, n times of substrate transfer and alignment are required. And, if the corresponding unit process is a thin film process, separate additional equipment or time for maintaining the vacuum is required.

On the other hand, if the unit film process is performed after masking the compartments for n mini-cells through the mask process, only one substrate transfer and alignment is required.

Therefore, the tandem solar cell and module in Example 2 of the present invention and the manufacturing method thereof have excellent photoelectric conversion efficiency due to excellent uniformity of the unit film and excellent productivity compared to the prior art.

<Modularization of tandem solar cells>

A plurality of tandem solar cells manufactured by Examples 1 and 2 above are used as solar cell modules through a modularization process in which a plurality of tandem solar cells are electrically connected in series or parallel.

This is because the electromotive force generated by each single solar cell is not sufficient for commercial use.

In the case of a conventional crystalline silicon solar cell (c-Si) solar cell, bus electrodes or bus bar electrodes and ribbons have been electrically bonded through soldering in the tabbing step before the lamination step.

However, the tandem solar cell in the present invention includes a perovskite absorbing layer, and the perovskite absorbing layer has characteristics that are very vulnerable to heat and moisture.

Specifically, it has been reported that the perovskite material is very vulnerable at high temperatures, and that the CH ₃ NH ₃ PbI ₃ light absorbing layer is decomposed after 3 hours at 150° C. or higher even in a vacuum, resulting in cell deterioration. On the other hand, it has been reported that the atmosphere remains stable in a vacuum or N ₂ , O ₂ atmosphere even when exposed to 24 hours at 85°C. This means that the perovskite unit film adopted in the present invention is very vulnerable to heat, and a low-temperature process controlled so as not to exceed 150 ° C. should be performed during the module process.

Therefore, a solar cell including a perovskite absorber layer must avoid a high-temperature process not only in a solar cell process but also in a subsequent module process in order to prevent decomposition of the perovskite absorber layer due to heat.

This means that the high-temperature soldering process in the tabbing step included in the conventional crystalline silicon solar cell module manufacturing method can no longer be used in a solar cell including a perovskite absorber layer.

Meanwhile, an alignment between a bus bar electrode in each solar cell and a ribbon connecting the solar cells is a very important factor in determining the yield of a solar cell module process. This is because, if the bus bar electrode and the ribbon are not aligned, the charge carriers generated by the solar cell cannot be efficiently collected, and the lower surface of the ribbon does not absorb sunlight, resulting in photoelectric conversion due to the decrease in effective surface area. This is because it causes a decrease in efficiency.

Therefore, in the present invention, when mini-cells of the tandem solar cell of Examples 1 and 2 are modularized, alignment of the mini-cells of the solar cell is secured without applying a high-temperature process, thereby securing photoelectric conversion efficiency. Tandem solar cell Modules and modularization plans were developed.

5 shows one embodiment of a cross section of a solar cell module that can be applied to the solar cell module of the present invention.

As shown in FIG. 5, the solar cell module 100 of the present invention includes a plurality of solar cells 150 and a wiring member 142 (eg, ribbon) electrically connecting the plurality of solar cells 150. do. In addition, the solar cell module 100 includes an encapsulant 130 including a first encapsulant 131 and a second encapsulant 132 that enclose and seal the plurality of solar cells 150 and the wiring member 142 connecting them. And, the first protection member 110 positioned on the first surface of the solar cell 150 on the encapsulant 130 and the second protection positioned on the second surface of the solar cell 150 on the encapsulant 130 It includes member 120.

Each of the plurality of solar cells 150 in the present invention corresponds to a mini cell whose size is determined in the previous scribing step.

In this case, each of the first protective member 110 and the second protective member 120 may be made of an insulating material capable of protecting the solar cell 150 from external shock, moisture, ultraviolet rays, and the like.

Meanwhile, the first protective member 110 may be made of a light-transmitting material through which light may pass, and the second protective member 120 may be made of a sheet made of a light-transmitting material, a non-transmissive material, or a reflective material. For example, the first protective member 110 may be composed of a glass substrate, etc., and the second protective member 120 may have a TPT (Tedlar/PET/Tedlar) type, Glass or a base film (eg, It may include a polyvinylidene fluoride (PVDF) resin layer formed on at least one surface of polyethylene terephthalate (PET).

At this time, the first protective member 110 mainly uses so-called white glass having a low content of iron (Fe) to increase transmittance of sunlight, particularly sunlight in a wavelength range of 380 to 1,100 nm. In addition, the glass for the front glass plate 110 may be tempered, if necessary, to protect the solar cell 150 from impact or foreign matter from the outside.

The plurality of solar cells 150 in the present invention may be electrically connected in series, parallel, or series-parallel by the wiring member 142, and the present invention does not specifically limit the electrical connection method.

FIG. 6 is a perspective view schematically illustrating a first solar cell 151 and a second solar cell 152 included in the solar cell module 100 shown in FIG. 5 and connected by a wiring member 142 .

5 and 6, two solar cells 150 (for example, a first solar cell 151 and a second solar cell 152) adjacent to each other among a plurality of solar cells 150 are wiring members 142 ) can be connected.

At this time, the wiring member 142 includes the upper electrode 42 located on the front side of the first solar cell 151 and the second solar cell 152 located on one side (lower left side of the drawing) of the first solar cell 151. The lower electrode 44 located on the rear side of the is connected. In addition, another wiring member 1420a is located on the lower electrode 44 located on the rear side of the first solar cell 151 and the upper side located on the front side of the other solar cell to be located on the other side (right side of the drawing) of the first solar cell 151. Connect electrode 42. In addition, another wiring member 1420b is located on the upper electrode 42 located on the front side of the second solar cell 152 and on the rear side of another solar cell to be located on one side (left side of the drawing) of the second solar cell 152. The second electrode 44 is connected. Accordingly, the plurality of solar cells 150 may be connected to each other to form a single column by the wiring members 142 , 1420a and 1420b.

At this time, the width W1 of the wiring member 142 may be smaller than the pitch of the finger line 427, which is an electrode directed in a direction perpendicular to the wiring member direction in FIG. 6, and may be larger than the width of the finger line 427 . However, the present invention is not limited thereto and various modifications are possible.

7 is a cross-sectional view showing a bonding relationship between a wiring member and a solar cell.

As shown in FIG. 7, in the solar cell of the present invention, an electro-conductive adhesive (electro-conductive adhesive, Modularization is achieved by fixing the bus bar electrodes and wiring members by locating ECA).

Here, the electrically conductive adhesive is a mixture in which metal particles of micro, meso, or nano size are dispersed in an adhesive polymer such as epoxy, polyurethane, silicone, polyimide, phenol, or polyester. am. In this case, the metal particles may include silver, copper, aluminum, tin, or an alloy thereof.

Thereafter, a subsequent low-temperature subsequent process (eg, lamination process) of 150° C. or less may be performed as needed. If the low-temperature post-process is performed, most of the organic materials including the polymer constituting the electrically conductive adhesive are burned out, and the remaining conductive metal particles react with the wiring material by diffusion to form an intermetallic compound. A eutectic mixture containing ) may be newly formed. Since the main component of the eutectic mixture is made of metal, adhesion between the bus bar electrode and the wiring member and electrical conductivity can be further increased.

Meanwhile, the first encapsulant 131 and the second encapsulant 132 prevent moisture and oxygen from entering and chemically combine each element of the solar cell module 100 . The first and second encapsulants 131 and 132 may be made of an insulating material having light-transmitting and adhesive properties. For example, ethylene-vinyl acetate copolymer resin (EVA), polyvinyl butyral, silicon resin, ester-based resin, or olefin-based resin may be used as the first encapsulant 131 and the second encapsulant 132 .

The second protective member 120, the second encapsulant 132, the solar cell 150, the first encapsulant 131, the first encapsulant 131, the first encapsulant 131, the first The protective member 110 may be integrated to form the solar cell module 100 .

Through the low-temperature modularization process using such an electrically conductive adhesive, the tandem solar cell of the present invention can be manufactured as a module. In addition, the tandem solar cell of the present invention manufactured by the above method avoids deterioration of photoelectric conversion efficiency by preventing deterioration of the perovskite unit film through a low-temperature process.

8 is a cross-sectional view showing an example in which two adjacent solar cells among a plurality of solar cells 150 are connected without a wiring material, corresponding to another embodiment of the modularization process of the present invention.

As shown in FIG. 8, the solar cells in the form of mini cells according to the present invention are directly connected to each other via electrically conductive adhesive (ECA) without a separate wiring material between bus bars located on the front or rear surfaces of each cell. it did In this case, the electrically conductive adhesive is substantially the same as the electrically conductive adhesive used in FIG. 7 above.

The modularization method as shown in FIG. 8 has advantages in that it is economical because it can be modularized without a wiring material, and furthermore, since the area of the solar cell per unit area can be more compactly arranged, the power per unit area can be increased.

As described above, the present invention has been described with reference to the drawings illustrated, but the present invention is not limited by the embodiments and drawings disclosed herein, and various modifications are made by those skilled in the art within the scope of the technical idea of the present invention. It is obvious that variations can be made. In addition, although the operation and effect according to the configuration of the present invention have not been explicitly described and described while describing the embodiments of the present invention above, it is natural that the effects predictable by the corresponding configuration should also be recognized.

Claims (11)

a plurality of tandem solar cells including an upper solar cell including a perovskite absorbing layer and a lower solar cell positioned below the upper solar cell;
bus bar electrodes positioned on the upper and lower solar cells;
a wiring member interconnecting bus bar electrodes of each of the plurality of tandem solar cells; In the modularization method of a tandem solar cell module comprising a,
An electrically conductive adhesive containing an adhesive polymer and metal particles is placed between the bus bar electrode and the wiring member to fix the bus bar electrode and the wiring member,
Thereafter, a low-temperature post-process is performed to burn out the polymer in the electrically conductive adhesive and form a co-mixture. delete According to claim 1,
The bus bar electrodes directly contact each other;
Modularization method of a tandem solar cell module, characterized in that. According to claim 1,
The lower solar cell is a crystalline silicon solar cell;
Modularization method of a tandem solar cell module, characterized in that. According to claim 4,
The crystalline silicon solar cell is a heterojunction solar cell;
Modularization method of a tandem solar cell module, characterized in that. According to claim 1,
The electrically conductive adhesive includes at least one or more adhesive polymers selected from the group consisting of epoxy, polyurethane, silicone, polyimide, phenol, and polyester;
micro, meso, or nano-sized dispersed metal particles;
Modularization method of a tandem solar cell module comprising a. delete positioning lower solar cell unit films constituting a lower solar cell on a substrate;
placing an intermediate layer on the lower solar cell;
Placing upper solar cell unit films constituting an upper solar cell including a perovskite absorbing layer on the intermediate layer;
a scribing step of dividing a substrate into an arbitrary mini-cell size in an arbitrary step among the steps of positioning the unit films constituting the upper solar cell;
Method for manufacturing a tandem solar cell module further comprising a. According to claim 8,
The scribing step is located between arbitrary steps among the steps of forming an electron transport layer, a perovskite absorbing layer, and a hole transport layer among unit films of the upper solar cell;
Method for manufacturing a tandem solar cell module, characterized in that. positioning lower solar cell unit films constituting a lower solar cell on a substrate;
placing an intermediate layer on the lower solar cell;
positioning upper solar cell unit films constituting an upper solar cell including a perovskite absorbing layer on the intermediate layer;
A scribing step of dividing the substrate into an arbitrary mini-cell size after locating the upper solar cell,
a masking step of forming a mask between mini cells on the substrate in an arbitrary step among the step of positioning the unit films constituting the upper solar cell;
Method for manufacturing a tandem solar cell module further comprising a. According to claim 10,
The masking step is located between arbitrary steps among the steps of forming an electron transport layer, a perovskite absorbing layer, and a hole transport layer among unit films of the upper solar cell;
Method for manufacturing a tandem solar cell module, characterized in that.

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