KR102531881B1 - Tandem solar cell - Google Patents

Abstract

The present invention relates to a tandem solar cell, which improves transmittance and improves electrical junction reliability through the design of the structure and material of the intermediate layer between the first and second cells in the tandem solar cell, resulting in excellent photoelectric conversion It relates to a tandem solar cell with improved efficiency and electrical contact.
According to the present invention, a first solar cell; a second solar cell positioned on the first solar cell; and an intermediate layer positioned between the first solar cell and the second solar cell, wherein the intermediate layer includes first patterns made of an electrically conductive material; Second patterns positioned between the first patterns and composed of a dielectric (high K); By providing a tandem solar cell, characterized in that it includes, suppressing reflection of sunlight and simultaneously increasing light transmittance and parasitic absorption can be suppressed to maximize the photoelectric conversion efficiency of the solar cell.

Description

Tandem solar cell {TANDEM SOLAR CELL}

The present invention relates to a tandem solar cell, and more specifically, to improve transmittance and electrical junction reliability through the design of the structure and material of the intermediate layer between the first solar cell and the second solar cell in the tandem solar cell, thereby improving It relates to a tandem solar cell with excellent photoelectric conversion efficiency and improved electrical contact.

A crystalline silicon (c-Si) solar cell is a typical 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 solar cell is composed of 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 in an intermediate layer (tunnel junction layer, junction layer or interlayer). -layer) is used as a medium for tunnel bonding.

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.

A conventional tandem solar cell is implemented using a transparent conductive oxide, a carbonaceous conductive material, or a metallic material having relatively excellent light transmittance and electrical conductivity as an intermediate layer, or an n-type or p-type material is doped into the intermediate layer.

However, even though it is a transparent conductive oxide, it is known that absorption and reflection of sunlight occur, and in particular, sunlight in a short wavelength band is relatively highly reflected. Reflection of sunlight in the intermediate layer eventually causes a problem of lowering the photoelectric conversion efficiency of the solar cell.

On the other hand, high-K dielectric materials with high transmittance to sunlight have a favorable effect on photoelectric conversion efficiency due to their excellent light transmittance, but have a negative effect on charge carriers such as electrons and holes. has no tunneling effect.

When the movement of electrons or holes becomes difficult, this means that single junction solar cells having different band gaps cannot electrically contact each other. As a result, another problem may arise in that electrons and holes excited by sunlight cannot recombine with each other and the possibility of parasitic absorption increases.

An object of the present invention is to provide a tandem solar cell in which light transmittance is improved by applying a new material to an intermediate layer between a first solar cell and a second solar cell in a tandem solar cell, thereby improving photoelectric conversion efficiency. .

In addition, the tandem solar cell in the present invention secures the electrical connection between the first solar cell and the second solar cell by newly designing the structure of the intermediate layer between the first solar cell and the second solar cell and further minimizes parasitic absorption aims to do

In order to solve the above technical problem, according to an aspect of the present invention, a first solar cell; a second solar cell positioned on the first solar cell; and an intermediate layer positioned between the first solar cell and the second solar cell, wherein the intermediate layer includes first patterns made of an electrically conductive material; A tandem solar cell may be provided, characterized in that it includes; second patterns disposed between the first patterns and made of a dielectric material (high K).

Preferably, the electrically conductive material is a transparent conductive oxide, a carbonaceous conductive material, or a metallic material; A tandem solar cell characterized by can be provided.

Preferably, the dielectric is one or more of ZrO ₂ , HfO ₂ , Y ₂ O ₃ ; A tandem solar cell characterized by can be provided.

Preferably, the first patterns and the second patterns are alternately positioned; A tandem solar cell characterized by can be provided.

Preferably, the thickness of the intermediate layer is 10 to 40 nm; a tandem solar cell characterized in that can be provided.

Preferably, the area ratio of the first patterns and the second patterns is 30:70 to 70:30; A tandem solar cell characterized by can be provided.

Preferably, the average width of the first patterns and the second patterns is within 10 ~ 300㎛; A tandem solar cell characterized by can be provided.

Preferably, the band gap of the second solar cell is larger than that of the first solar cell; A temdom solar cell characterized by may be provided.

Preferably, the first solar cell includes a substrate; a first conductive layer positioned on a first surface of the substrate; A tandem solar cell may be provided, characterized in that it includes; a second conductive layer positioned on a second surface of the substrate.

At this time, the first solar cell may include a first passivation film positioned between the substrate and the first conductive layer; The first solar cell may include a second passivation film positioned between the substrate and the second conductive layer. A tandem solar cell may be provided.

Meanwhile, a tandem solar cell characterized in that the substrate and the first conductivity type layer have the same conductivity type may be provided.

Alternatively, a tandem solar cell characterized in that the substrate and the second conductivity type layer have the same conductivity type may be provided.

Preferably, the second solar cell includes a first conductivity type charge transport layer; a perovskite absorption layer positioned on the first conductivity type charge transport layer; a second conductivity-type charge transport layer positioned on the perovskite absorption layer; A tandem solar cell comprising a can be provided.

In this case, the perovskite absorbing layer includes FA _{1- x} Cs _x PbBr _y I _{3 -y} ; A tandem solar cell characterized by can be provided. (However, 0 ≤ x ≤ 1, 0 ≤ y ≤ 3)

According to the present invention, photoelectric conversion efficiency can be achieved by suppressing reflection of sunlight and increasing light transmittance by applying a new material called dielectric to the intermediate layer between the first and second solar cells in a tandem solar cell.

In particular, there is an effect of improving photoelectric conversion efficiency by improving light transmittance by partially substituting a conventional electrically conductive material having high reflectance in short-wavelength sunlight with a dielectric.

In the present invention, by forming the structure of the intermediate layer with the first patterns of electrically conductive material and the second patterns of dielectric, the movement of charge carriers such as electrons and holes that inevitably occur in the intermediate layer made of dielectric is slowed down and recombination is difficult. phenomenon can be prevented.

Specifically, by including first patterns made of an electrically conductive material in the intermediate layer, recombination of electrons and holes generated in the first solar cell and the second solar cell occurs through the first patterns, thereby suppressing parasitic absorption in the intermediate layer. There are possible effects.

As a result, the photoelectric conversion efficiency of the entire tandem solar cell can be improved due to the reduced parasitic absorption.

1 is a schematic diagram schematically showing a general tandem solar cell.
2 is a cross-sectional view showing a tandem solar cell according to an embodiment of the present invention.
3 to 15 are cross-sectional views showing a method of manufacturing a tandem solar cell step by step according to the present invention and a specific process sequence for forming an intermediate layer according to the present invention.

Hereinafter, a 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 divided into and implemented.

tandem solar cell

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

Specifically, FIG. 2 shows that the second solar cell 120 including an absorber layer having a relatively large band gap and the first solar cell 110 including an absorber layer having a relatively small band gap are interlayer 114 (hereinafter referred to as " It shows the structure of a 2-terminal tandem solar cell 100 directly tunnel-junctioned via a “tunnel junction layer”, “junction layer”, or “inter-layer”) as a medium.

Accordingly, among light incident to the tandem solar cell 100, light in the short wavelength region is absorbed by the second solar cell 120 to generate electric charge, and light in the long wavelength region passing through the second solar cell 120 is 1 is absorbed by the solar cell 110 to generate charge.

In addition, by absorbing and generating light in the long wavelength region in the first solar cell 110, the threshold wavelength can be moved to the long wavelength side, and as a result, the wavelength band absorbed by the entire solar cell can be widened. .

A tandem solar cell 100 according to an embodiment of the present invention includes a first solar cell 110 and a second solar cell 120 .

In this case, the first solar cell may be a silicon solar cell, and the second solar cell on the first solar cell may be a perovskite solar cell, but is not necessarily limited thereto. The second solar cell in the present invention can be applied to any solar cell positioned on the first solar cell and having a bandgap larger than that of the first solar cell.

A tandem solar cell 100 as an embodiment of the present invention includes a first solar cell 110; a second solar cell 120 positioned on the first solar cell 110; and an intermediate layer 114 positioned between the first solar cell and the second solar cell, wherein the intermediate layer includes first patterns 114-1 made of an electrically conductive material; and second patterns 114-2 positioned between the first patterns and made of a dielectric material (high K).

In general, a tandem solar cell includes an intermediate layer 114 for charge transfer between the first solar cell 110 and the second solar cell 120 . In this case, the intermediate layer 114 is made of a transparent conductive oxide, a carbonaceous conductive material, or a metallic material so that sunlight passing through the second solar cell 120 can be incident to the first solar cell 110 below without transmission loss. can be implemented using In addition, the intermediate layer 114 may be doped with an n-type or p-type material.

Transparent conductive oxides (TCO) include 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 may be used.

Graphene or carbon nanotubes may be used as the carbonaceous conductive material, and metal thin films having a multilayer structure such as metal (Ag) nanowires or Au/Ag/Cu/Mg/Mo/Ti may be used as the metallic material. there is.

However, in addition to electrical conductivity, the conductive materials must have excellent optical properties such as light transmittance in order to absorb sunlight in the first solar cell. Therefore, when a carbonaceous conductive material or a metallic material is applied in addition to the transparent conductive oxide for optical properties, the light transmittance is controlled through thickness control.

Meanwhile, even if it is a transparent conductive oxide, it is known that transmittance is low for sunlight in some wavelength ranges. In particular, it is known that the reflectivity of sunlight in the short wavelength range is very high compared to that in the long wavelength range. As described above, the high reflectivity of the transparent conductive oxide is a further problem in a double-sided transmissive solar cell.

In the present invention, in order to improve the light reflectivity of a conductive material such as a transparent conductive oxide, first, a dielectric having relatively high light transmittance compared to the transparent conductive oxide is included on the intermediate layer 114 .

At this time, the dielectric in the present invention is based on a so-called high-K material. Specifically, the dielectric is characterized in that at least one of ZrO ₂ , HfO ₂ , Y ₂ O ₃ .

On the other hand, if the intermediate layer 114 including the dielectric 114-2 in the present invention is made of only the dielectric, it is difficult to expect a tunneling effect due to the characteristics of high-K. This means that the unique function of a tandem solar cell cannot be achieved because electrical connection between the first solar cell 110 and the second solar cell 120 is impossible.

Accordingly, in the present invention, in order to electrically connect the first solar cell 110 and the second solar cell 120, the intermediate layer including the dielectric 114-2 includes electrical conductivity including a transparent conductive oxide (TCO). Including additional material.

At this time, it is preferable that the first patterns 114-1 made of the electrically conductive material and the second patterns 114-2 made of the dielectric are alternately positioned. More specifically, the intermediate layer 114 includes first patterns 114-1 made of an electrically conductive material and second patterns 114-2 made of a dielectric (high K) located between the first patterns. It is more preferable to make

At this time, it is preferable that the first patterns 114-1 made of the electrically conductive material and the second patterns 114-2 made of the dielectric are alternately positioned. More specifically, the intermediate layer 114 includes first patterns 114-1 made of an electrically conductive material and second patterns 114-2 made of a dielectric (high K) located between the first patterns. It is more preferable to make

If the thickness of the intermediate layer 114 is 10 nm or less, the specific resistance of the intermediate layer excessively increases and the mobility of charge carriers decreases, resulting in poor electrical characteristics. On the other hand, when the thickness of the intermediate layer 114 is 50 nm or more, the light transmittance is excessively reduced due to the thickness of the dielectric 114-2 that is too thick.

In addition, it is preferable that the area ratio (ie, width ratio) of the first patterns 114-1 and the second patterns 114-2 is 30:70 to 70:30.

If the ratio of the first patterns is less than 30%, charge transfer between the first solar cell and the second solar cell is not smooth, so that the intermediate layer does not participate in photoelectric conversion and parasitic absorption is increased. Furthermore, since current matching between the first solar cell and the second solar cell is not smooth, as a result, there is a problem in that short-circuit current Jsc cannot be increased.

On the other hand, when the ratio of the first patterns is greater than 70%, the reflectance of sunlight in the short wavelength band becomes excessively high.

In addition, it is preferable that the average width of the first patterns 114-1 and the second patterns 114-2 is within 500 μm. In particular, the average width of the first patterns 114-1 and the second patterns 114-2 is preferably within a range of 10 to 300 μm.

If the lower limit value of the average width of the patterns is not particularly limited. However, considering process capability and productivity considering a process window and light scattering that occurs when a substrate has a texture, the lower limit of the average width of the patterns is preferably 10 μm or more.

On the other hand, the upper limit of the average width of the patterns is preferably within 500 μm, more preferably within 300 μm. If the patterns are wider than 500 μm, holes and electrons generated in the first solar cell and the second solar cell due to the excessively wide second patterns 114-2 are formed of dielectric second patterns 114-2. ) causes them to move too far before recombination, which increases the possibility of parasitic absorption.

Meanwhile, the present invention includes a first solar cell and a second solar cell having a bandgap larger than that of the first solar cell.

In this case, the first solar cell may be a silicon solar cell, and the second solar cell on the first solar cell may be a perovskite solar cell, but is not necessarily limited thereto.

The first solar cell 110 in the present invention includes a crystalline silicon substrate 111; a second passivation film 112-1 positioned on the second surface of the crystalline silicon substrate; a second conductive layer 112-2 positioned on the second passivation layer 112-1; a first passivation film 113-1 positioned on a first surface of the crystalline silicon substrate; a first conductive layer 113-2 positioned on the first passivation film 113-1; and a first electrode 140 positioned on the first conductive layer 113-2.

More specifically, the crystalline silicon substrate 111 may be formed of a single crystal or polycrystalline semiconductor (eg, single crystal or polycrystalline silicon). In particular, the crystalline silicon substrate 111 may be composed of a single-crystal semiconductor (eg, a single-crystal semiconductor wafer, more specifically, a single-crystal silicon wafer). In this way, when the crystalline silicon substrate 111 is formed of a single crystal semiconductor (eg, single crystal silicon), the first solar cell 110 constitutes a single crystal semiconductor solar cell (eg, a single crystal silicon solar cell).

In general, single-crystal semiconductor substrates have fewer 1-dimensional defects such as dislocations as well as 2-dimensional defects such as grain boundaries compared to poly-crystal semiconductor substrates. When such defects exist in a crystal, a strain field is generated around the defect, which hinders the flow of charge carriers such as electrons. Therefore, the first solar cell 110 based on the substrate 111 composed of a single crystal semiconductor having fewer defects has higher charge mobility than a polycrystalline semiconductor, and thus may have excellent electrical characteristics.

In this embodiment, a separate doped region is not formed on the substrate 111 and the semiconductor substrate 111 may be composed of only the base region. In this way, if a separate doped region is not formed on the substrate 111, damage to the substrate 111 that may occur when forming the doped region and an increase in defects are fundamentally prevented so that the substrate 111 has excellent passivation characteristics. can Accordingly, surface recombination occurring on the surface of the crystalline silicon substrate 111 may be minimized.

Also, in the present embodiment, the substrate 111 may be doped with a first conductivity type dopant, which is a base dopant, at a low doping concentration to have a conductivity type. In this case, the semiconductor substrate 111 may have a lower doping concentration, higher resistance, or lower carrier concentration than the electric field region having the same conductivity type.

Meanwhile, in a single junction solar cell, it is common to introduce a texture structure to the surface in order to reduce the reflectance of incident light on the surface and increase the path of light incident to the solar cell. Accordingly, when the first solar cell in the tandem solar cell 100 according to the present invention is a crystalline silicon solar cell, a texture may be formed on the surface (at least the rear surface) of the first solar cell 110 as well.

A second passivation film 112 - 1 is positioned on the second surface of the crystalline silicon substrate 111 , and a first passivation film 113 - 1 is formed on the first surface of the crystalline silicon substrate 111 . As a result, the first and second surfaces of the crystalline silicon substrate 111 may be passivated, respectively.

In the present invention, the terms first passivation film 113-1 and second passivation film 112-1 are used, but the first passivation film 113-1 and/or the second passivation film 112-1 It can also serve as a tunneling film. That is, the first and second passivation films 113-1 and 112-1 act as a kind of barrier to electrons and holes to prevent minority carriers from passing through, and the first and second passivation films 113-1 and 112-1 After being accumulated in portions adjacent to the films 113-1 and 112-1, only a majority carrier having a certain energy can pass through the first and second passivation films 113-1 and 112-1, respectively. let it be At this time, the majority carriers having a certain energy can easily pass through the first and second passivation films 113-1 and 112-1 due to the tunneling effect. Here, the passivation films 113-1 and 112-1 may have a thickness smaller than that of the first conductive layer 113-2 and the second conductive layer 112-2 so as to sufficiently implement the tunneling effect.

For example, the first and second passivation layers 113-1 and 112-1 may include an intrinsic amorphous semiconductor. For example, the first and second passivation layers 113-1 and 112-1 may be formed of an intrinsic amorphous silicon (i-a-Si) layer. Then, since the first and second passivation films 113-1 and 112-1 contain the same semiconductor material as the substrate 111 and have similar properties, the surface properties of the substrate 111 can be improved more effectively. As a result, passivation characteristics can be greatly improved.

In general, an amorphous silicon (i-a-Si) layer has an energy band gap of about 0.6 to 0.7 eV compared to a crystalline silicon layer having an energy band gap of about 1.1 eV. there is The advantage of such an amorphous silicon layer is that it can increase light utilization by minimizing light absorption loss in a short wavelength region, and can bring a high open-circuit voltage and front field effect.

Meanwhile, in the case of heterojunctions having different band gaps, there is a very high possibility of lattice mismatch between different materials. However, when an amorphous silicon layer is used, lattice mismatch does not occur because the crystal lattice of amorphous silicon is composed of non-regularity unlike crystalline silicon layer. As a result, when the intrinsic amorphous silicon layer (i a-Si) is deposited on the crystalline silicon substrate, recombination on the surface of the silicon substrate can be effectively reduced.

It is more preferable to use a hydrogenated intrinsic amorphous silicon layer (i a-Si:H) as the intrinsic amorphous silicon layer in the present invention. This is because, by the hydrogenation reaction, hydrogen enters the amorphous silicon to reduce the dangling bond of the amorphous silicon and the localized energy state within the energy band gap.

However, the present invention is not limited thereto. Accordingly, the first and/or second passivation layers 113-1 and 112-1 may include an intrinsic amorphous silicon carbide (i-a-SiCx) layer or an intrinsic amorphous silicon oxide (i-a-SiOx) layer. Such an amorphous silicon compound layer may have an improved effect due to a wider energy band gap compared to the intrinsic amorphous silicon layer, but may have slightly lower passivation characteristics than the case of including the intrinsic amorphous silicon (i-a-Si) layer.

A first conductivity type layer 113 - 2 having a first conductivity type may be formed on the first passivation layer 113 - 1 . A second conductivity type layer 112 - 2 having a second conductivity type opposite to the first conductivity type may be positioned on the second passivation layer 112 - 1 .

The first conductivity type layer 113 - 2 is a region having a first conductivity type including a first conductivity type dopant. The second conductivity type layer 112 - 2 may be a region having a second conductivity type including a second conductivity type dopant.

For example, the second conductivity type layer 112-2 has the same conductivity type as the substrate 111 and contacts the second passivation film 112-1, and the first conductivity type layer 113-2 has the same conductivity type as the substrate 111. It may have a different conductivity type and contact the first passivation film 113-1. Then, the second conductivity type layer 112-2 functions as an electric layer and the first conductivity type layer 113-2 functions as an emitter layer, and the structure of the tandem solar cell 100 is simplified and the first and second passivation films The tunneling effect of (113-1, 112-1) can be maximized.

However, the present invention is not limited thereto. Conversely, the second conductivity type layer 112-2 has a conductivity type different from that of the substrate 111 and contacts the second passivation film 112-1, and the first conductivity type layer 113-2 has a conductivity type different from that of the substrate 111. It may have the same conductivity type as that and contact the first passivation film 113-1. Then, the first conductivity type layer 113-2 can function as an electric layer and the second conductivity type layer 111-2 can function as an emitter layer.

Since the first conductivity type layer 113-2 and the second conductivity type layer 112-2 are formed separately from the crystalline silicon substrate 111 on the substrate 111, the first conductivity type layer 113-2 can be easily formed on the substrate 111. The type layer 113 - 2 and the second conductive type layer 112 - 2 may have a material and/or crystal structure different from that of the substrate 111 .

Meanwhile, each of the first conductivity-type layer 113-2 and the second conductivity-type layer 112-2 is formed by doping a first or second conductivity-type dopant on an amorphous semiconductor that can be easily manufactured by various methods such as deposition. It can be. Then, the first conductive layer 113-2 and the second conductive layer 112-2 can be easily formed by a simple process. At this time, as described above, when the first and second passivation films 113-1 and 112-1 are composed of an intrinsic amorphous semiconductor (eg, intrinsic amorphous silicon), the substrate, the passivation film, and the conductive layers have excellent adhesive properties, It may have excellent electrical conductivity and the like.

At this time, as the p-type dopant used as the first or second conductivity-type dopant, Group 3 elements such as boron (B), aluminum (Al), gallium (Ga), and indium (In) may be mentioned, and the n-type dopant Examples of the furnace include Group 5 elements such as phosphorus (P), arsenic (As), bismuth (Bi), and antimony (Sb). However, the present invention is not limited thereto, and various dopants may be used as the first or second conductivity type dopant.

For example, the substrate 111 and the second conductive layer 112-2 may have an n-type, and the first conductive layer 113-2 may have a p-type. According to this, since the substrate 111 is n-type, the life time of the carrier may be excellent. In this case, the crystalline silicon substrate 111 and the second conductive layer 112-2 may include phosphorus (P) as an n-type dopant, and the first conductive layer 113-2 may include boron ( B) can be included.

However, the present invention is not limited thereto, and the substrate 111 and the second conductive layer 112-2 may have a p-type, and the first conductive layer 113-2 may have an n-type.

Furthermore, the substrate 111 and the first conductive layer 113-2 may have an n-type, and the second conductive layer 112-2 may have a p-type.

In this embodiment, the first conductivity-type layer 113-2 and the second conductivity-type layer 112-2 are an amorphous silicon (a-Si) layer, an amorphous silicon oxide (a-SiOx) layer, and an amorphous silicon carbide (a-SiOx) layer, respectively. It may include at least one of a SiCx) layer, an indium-gallium-zinc oxide (IGZO) layer, a titanium oxide (TiOx) layer, and a molybdenum oxide (MoOx) layer.

In this case, an amorphous silicon (a-Si) layer, an amorphous silicon oxide (a-SiOx) layer, and an amorphous silicon carbide (a-SiCx) applied to the first conductive layer 113-2 and the second conductive layer 112-2. ) layer may be doped with a first or second conductivity type dopant.

In addition to materials included in the oxide layer, the indium-gallium-zinc oxide layer, the titanium oxide layer, and the molybdenum oxide layer applied to the first conductive layer 113-2 and the second conductive layer 112-2 are the first and second conductive layers. It does not include a group 3 element or a group 5 element (eg, boron, phosphorus) used as a 2-conductivity type dopant. The indium-gallium-zinc oxide layer, the titanium oxide layer, and the molybdenum oxide layer can selectively collect electrons or holes to perform the same role as the n-type or p-type conductive region. More specifically, the indium-gallium-zinc oxide layer may have n-type conductivity, the titanium oxide layer may have n-type conductivity, and the molybdenum oxide layer may have p-type conductivity.

The amorphous silicon (a-Si) layer, the amorphous silicon oxide (a-SiOx) layer, and the amorphous silicon carbide (a-SiCx) layer are semiconductor materials constituting the substrate 111, although their crystal structure is different from that of the crystalline silicon substrate 111. (For example, silicon) and may have characteristics similar to those of the substrate 111 . Accordingly, as in the case of the first and second passivation layers 113-1 and 112-1, a characteristic difference that may occur when a material different from the semiconductor material of the substrate 111 is included can be minimized. Among them, the amorphous silicon oxide layer and the amorphous silicon carbide layer have a high energy band gap so that energy band bending occurs sufficiently to selectively pass carriers. In addition, the indium-gallium-zinc oxide (IGZO) layer, the titanium oxide (TiOx) layer, and the molybdenum oxide (MoOx) layer have a wide energy bandgap and have low light absorption, thereby minimizing light loss. .

For example, among the first conductivity type layer 113-2 and the second conductivity type layer 112-2, the conductivity type layer functioning as an electric layer having the same conductivity type as the substrate is indium-gallium-zinc oxide having low light absorption. layer, a titanium oxide layer, and a molybdenum oxide layer. Accordingly, absorption of light in the entire layer can be minimized.

Among the first conductivity type layer 113-2 and the second conductivity type layer 112-2, the conductivity type layer functioning as an emitter layer having a conductivity type different from that of the substrate is an amorphous silicon layer, an amorphous silicon oxide layer, and an amorphous silicon carbide At least one of the layers may be included. Since the emitter layer is a layer directly involved in photoelectric conversion by forming a pn junction (or a pin junction with a passivation film therebetween) with the substrate 111, it contains the same semiconductor material (i.e., silicon) as the substrate 111 and has similar characteristics. It is possible to make the movement of the carrier more effective by having

Referring back to FIG. 2 , the first electrode 140 electrically connected to the first solar cell is positioned (eg, contacted) on the first conductive layer 113 - 2 . The first electrode 140 selectively first includes a transparent electrode layer 115 positioned on the first conductive layer 113-2. Materials for the transparent electrode layer include transparent conductive oxides such as indium tin oxide (ITO), zinc indium tin oxide (ZITO), zinc indium oxide (ZIO), and zinc tin oxide (ZTO).

After the transparent electrode layer 115 is positioned, a grid electrode 116 is positioned thereon. Of course, the grid electrode 116 may be positioned directly on the first conductive layer 113-2 without forming the transparent electrode layer 115. However, since the first conductive layer has a relatively low carrier mobility to collect carriers through the metal grid, it is more preferable to form the transparent electrode layer 115 first.

The paste for the grid electrode 116 of the first electrode 140 in the present invention may or may not include a glass frit.

First, the grid electrode 116 of the first electrode 140 may be manufactured by selectively applying a first electrode paste that does not include a glass frit and then firing at a low temperature at a temperature at which the first electrode 140 is formed. . In this case, the first electrode paste may include metal particles and an organic material that is a binder for low-temperature firing, and the first electrode paste does not include a glass frit. At this time, the formation temperature of the grid electrode 116 of the first electrode 140 may be 250° C. or less, more specifically, 100 to 200° C. In this way, when the first electrode 140 is formed at a low temperature, the first electrode 140 can be formed in the same step as the second electrode 130 to be described later, which is more advantageous in terms of productivity by reducing the number of processes. it gets done

Alternatively, the grid electrode 116 of the first electrode 140 may be manufactured by selectively applying a paste including a glass frit and then firing at a high temperature at the forming temperature of the first electrode 140 . In this case, the paste for the grid electrode 116 of the first electrode 140 includes not only organic materials such as metal particles and binders, but also inorganic particles such as glass frit that require a high temperature for melting. At this time, since the formation temperature of the first electrode 140 is relatively higher than the formation temperature of the second electrode 130 to be described later, it is formed in a process separate from the second electrode.

The tandem solar cell 100 in the present invention includes not only the first solar cell 110 but also the second solar cell 120 on the first solar cell 110 .

The second solar cell 120 in the present invention, for example, first includes a first conductivity-type charge transport layer 121 positioned on the first solar cell; a perovskite absorption layer 122 positioned on the first conductivity type charge transport layer; a second conductivity type charge transport layer 123 positioned on the perovskite absorption layer 122; and a second electrode 130 positioned on the second conductivity type charge transport layer.

As a specific example, when the crystalline silicon substrate 111 is an n-type single crystal silicon substrate and the second conductivity-type layer 112-2 is an n-type conductivity type, the first conductivity-type charge transport layer 121 in the second solar cell 120 ) becomes the p-type hole transport layer 121 and the second conductivity type charge transport layer 123 becomes the n-type electron transport layer 123 .

As another example, if the crystalline silicon substrate 111 is an n-type single-crystal silicon substrate and the second conductivity-type layer 112-2 is a p-type conductivity, the first conductivity-type charge transport layer in the second solar cell 120 (121) becomes the n-type electron transport layer 121 and the second conductivity type charge transport layer 123 becomes the p-type hole transport layer 123.

A conductive inorganic material layer may be used as a representative material that can be used as the first conductivity type charge transport layer 121 and the second conductivity type charge transport layer 123 in the present invention.

At this time, non-limiting examples of when the conductive inorganic layer is used as an electron transport layer include Ti oxide, Zn oxide, In oxide, Sn oxide, W oxide, Nb oxide, Mo oxide, Mg oxide, Zr oxide, Sr oxide, and Yr oxide. oxide, La oxide, V oxide, Al oxide, Y oxide, Sc oxide, Sm oxide, Ga oxide, In oxide, and SrTi oxide. More preferably, the electron transport layer may use at least one metal oxide selected from ZnO, TiO ₂ , SnO ₂ , WO ₃ and TiSrO ₃ .

On the other hand, when the conductive inorganic layer is used as a hole transport layer, possible metal oxides may be one or two or more selected from MoO _x , NiO, WO ₃ , CuSCN, CuI, CuO, Cu ₂ O, and VO _x .

Meanwhile, as the first conductivity-type charge transport layer 121 and the second conductivity-type charge transport layer 123 in the present invention, a conductive organic material layer or the like may be used.

For example, when the first conductivity type charge transport layer 121 or the second conductivity type charge transport layer 123 is a p-type hole transport layer, the hole 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 two or more are used.

On the other hand, when the first conductivity-type charge transport layer 121 or the second conductivity-type charge transport layer 123 is an n-type electron transport layer, fullerenes (C ₆₀ , C ₇₀ , C ₇₄ , C ₇₆ , C ₇₈ , C ₈₂ , C ₉₅ ), fullerenes including PCBM ([6,6]-phenyl-C61butyric acid methyl ester) and C71-PCBM, C84-PCBM, PC70BM ([6,6]-phenyl C70-butyric acid methyl ester) - One or two or more selected from Fulleren-derivative, PBI (polybenzimidazole), PTCBI (3,4,9,10-perylenetetracarboxylic bisbenzimidazole), and F4-TCNQ (tetra urorotetracyanoquinodimethane) are used.

Meanwhile, layers containing silicon (Si) may also be used as the first conductivity type charge transport layer 121 and the second conductivity type charge transport layer 123 in the present invention.

For example, when the first conductivity-type charge transport layer 121 or the second conductivity-type charge transport layer 123 is an n-type electron transport layer, the electron transport layer made of a layer containing silicon (Si) is 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-μc-Si), microcrystalline silicon oxide (n-μc-SiO), microcrystalline silicon carbide (n-μc-SiC), microcrystalline silicon It is made of a material containing one or more of crystalline silicon nitride (n-μc-SiN) and microcrystalline silicon germanium (n-μc-SiGe).

On the other hand, when the first conductivity-type charge transport layer 121 or the second conductivity-type charge transport layer 123 is a p-type hole transport layer, the hole transport layer made of a layer containing silicon (Si) 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-μc-Si), microcrystalline silicon oxide (p-μc-SiO), microcrystalline silicon carbide (p-μc-SiC), microcrystalline silicon nitride (p-μc-SiN) and microcrystalline silicon germanium (p-μc-SiGe).

A perovskite absorption layer 122 is positioned on the first conductivity type charge transport layer 121 .

The perovskite absorption layer 122 in the present invention can use all of the currently widely used so-called methylamminium (MA)-based or formamidinium (FA)-based perovskite compounds.

Among them, the FA-based perovskite compound 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.

In addition, this is because 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 to produce high voltage. can cause As a result, the efficiency of the solar cell is eventually increased.

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).

A second conductivity type charge transport layer 123 is positioned on the perovskite absorption layer 122, and a second electrode 130 is positioned on the second conductivity type charge transport layer again.

At this time, the second electrode 130 first includes a transparent electrode layer 125 . The transparent electrode layer 125 is formed on the entire top surface of the perovskite solar cell 120 and serves to collect electric charges generated by the perovskite solar cell 120 . The transparent electrode layer 125 may be implemented with various transparent conductive materials. As the transparent conductive material, the same material as that of the intermediate layer 114 may be used.

Next, the grid electrode 126 is positioned on the transparent electrode layer 125 and is disposed in a partial area of the transparent electrode layer 125 .

The grid electrode 126 of the second electrode 130 may be manufactured by selectively applying a second electrode paste that does not include a glass frit and then firing at a low temperature at a first temperature. Here, the second electrode paste may include metal particles and an organic material that is a binder for low-temperature firing, and the second electrode paste does not include a glass frit. In particular, the second temperature may be 250 or less, more specifically 100 to 200.

As described above, the grid electrode 116 of the first electrode and the grid electrode 126 of the second electrode may be formed simultaneously when forming the second electrode 130 or form the first electrode 140. After forming the second solar cell, the second electrode 130 may be formed. If the grid electrode 116 of the first electrode and the grid electrode 126 of the second electrode are formed at the same time, at this time, both the first electrode 140 and the second electrode 130 are below 250 ° C. It is formed by a low-temperature firing process.

tandem Solar cell manufacturing method

3 to 15 are cross-sectional views showing a method of manufacturing a tandem solar cell step by step according to the present invention and a specific process sequence for forming an intermediate layer according to the present invention.

To manufacture the tandem solar cell in the present invention, a crystalline silicon solar cell is first prepared.

More specifically, as shown in FIG. 3 , a texturing pattern is formed by first planarizing the front and rear surfaces of the crystalline silicon substrate 111 and then, if necessary, at least one of the front and rear surfaces is textured.

Alternatively, a planarized flat crystalline silicon substrate 111 may be used. A textured substrate has an advantage of increasing the light absorption rate, whereas a flat substrate has a more advantageous advantage in a method of forming an intermediate layer including patterns specific to the present invention.

At this time, any one of a wet chemical etching method, a dry chemical etching method, an electrochemical etching method, and a mechanical etching method may be used to introduce the texture structure of the crystalline silicon substrate 111, but is not necessarily limited thereto. For example, at least one of the first and second surfaces of the crystalline silicon substrate 111 may be etched in a basic aqueous solution to introduce a texture structure.

As a specific embodiment, in the present invention, first, an n-type silicon single crystal substrate having a thickness of tens to hundreds of μm sliced along a (100) plane was prepared. Next, an aqueous solution containing additives such as organic solvents, phosphates, reaction regulators and/or surfactants is used in a 1 to 5% by weight aqueous solution of sodium hydroxide (NaOH) or an aqueous solution of potassium hydroxide (KOH) in the temperature range of room temperature to 150 ° C. The surface of the substrate was etched.

The organic solvent is 2-methyl-2,4-pentanediol, propylene glycol, 2,2,4-trimethyl-1,3-pentanediol (2, 2,4-trimethyl-1,3-pentanediol), 1,3-butanediol (1,3-butanediol), 1,4-butanediol (1,4-butanediol), 1,6-hexanediol (1,6- hexanediol), 2,2-dimethyl-1,3-propanediol, hydroquinone, 1,4-cyclohexanediol, And it may be at least any one of N-methyl propyl (N-methyl proline).

Also, the phosphate may be at least one of K ₃ PO ₄ and K ₂ HPO ₄ .

Through the above etching, a texture having pyramidal irregularities was formed on the silicon single crystal substrate. Since silicon single crystal has a diamond cubic structure, the {111} plane is the most dense and chemically stable plane. Therefore, the etching rate of the sodium hydroxide solution is the slowest on the {111} plane, and as a result, anisotropic etching occurs along the {111} plane after etching. As a result, a texture with a depth of 0.1 to 10 μm was uniformly formed on the entire surface of the silicon substrate.

Next, as shown in FIG. 4 , a first passivation layer 113 - 1 and a second passivation layer 112 - 1 are formed on the first and second surfaces of the crystalline silicon substrate 111 , respectively.

In the case of a heterojunction silicon solar cell, first, an amorphous intrinsic silicon (ia-Si:H) layer is applied as passivation layers 112-1 and 113-1 on both sides of an n-type silicon crystalline substrate 111 having a uniform texture as a silicon source It is deposited by the PECVD method using materials (SiH ₄ , Si ₂ H _{6 ,} etc.) and hydrogen (H ₂ ). The PECVD method has the advantage of lowering the process temperature compared to the general CVD method, and is particularly preferable as a method for manufacturing a heterojunction silicon solar cell.

Next, a first conductive layer 113-2 doped with impurities of the same or opposite conductivity type as the silicon crystalline substrate 111 and impurities of the opposite conductivity type to the first conductive layer 113-2. A doped second conductivity type layer 112-2 is formed (FIGS. 5 and 6). At this time, the formation order of the first conductivity type layer 113-2 and the second conductivity type layer 112-2 may be formed first.

Specifically, by using the PECVD process, at least one gas selected from the group consisting of SiH ₄ , Si ₂ H ₆ , SiHCl ₃ and SiH ₂ Cl ₂ , H ₂ gas, and B ₂ H ₆ or PH as a dopant gas ₃ Gases are used as reactants. At this time, the temperature and pressure conditions of the PECVD process can be said to be the same as the PECVD conditions of the amorphous intrinsic silicon layer.

Unlike the above example, if the first solar cell 110 is a homojunction silicon solar cell, the emitter layer and the electric field layer are implanted without the passivation layers 112-1 and 113-1. It can be formed through a process. In this case, when the substrate is n-type doped, the emitter layer is doped with boron as an impurity, and the electric field layer is doped with phosphorus as an impurity.

Next, as shown in FIG. 7 , a first electrode 140 including a transparent electrode layer 115 and a grid electrode 116 is formed on the first conductive layer 113-2 of the crystalline silicon substrate 111. do.

In the case of a heterojunction silicon solar cell, as described above, in order to prevent hydrogen bond breakage inside amorphous silicon, the process temperature of the first electrode 140 (more specifically, the grid electrode 116) is set to the second electrode ( 130) (more specifically, the process temperature of the grid electrode 126) is limited to 250 or less. Accordingly, in this case, the first electrode 140 may be formed before the second electrode 130 or the first electrode 140 and the second electrode 130 may be formed simultaneously.

In the first electrode 140, a transparent electrode layer 115 is first formed on the first conductive layer 113-2. When a transparent conductive oxide such as ITO (Indium Tin Oxide), ZITO (Zinc Indium Tin Oxide), ZIO (Zinc Indium Oxide), ZTO (Zinc Tin Oxide) is used as a material for the transparent electrode layer, the transparent electrode layer 115 is formed through sputtering. may be deposited.

After forming the transparent electrode layer 115, a grid electrode 116 is formed. Of course, the grid electrode 116 may be formed directly on the first conductive layer 113-2 without forming the transparent electrode layer 115, but amorphous silicon is relatively difficult to collect carriers through the metal grid. Since the carrier mobility is low, it is more preferable to form the transparent electrode layer 115.

At this time, the grid electrode 116 is formed by printing the first electrode paste on the transparent electrode layer 115 by screen printing, and having a first temperature (250 or less, more specifically, 100 to 200, the same as the second temperature). formed by heat treatment.

Unlike this, in the case of a homojunction silicon solar cell, the first electrode 140 and the second electrode 130 are not formed at the same time, but a process of forming the first electrode 140 through a high-temperature firing process of 700 °C or more and a glass frit. The process of forming the second electrode 130 by firing at a low temperature of 250°C or less using the second electrode paste that does not contain may be performed in two ways.

An intermediate layer 114 is formed on the crystalline silicon solar cell 110 (FIG. 8).

A method of forming a pattern on the intermediate layer 114 between the crystalline silicon solar cell 110 and the perovskite solar cell 120 can be formed in various ways as shown in FIGS. 9 to 11 below.

First, as shown in FIG. 9 , a dielectric layer is formed on the second conductive layer 112-2. The dielectric layer may use one or more of ZrO ₂ , HfO ₂ , and Y ₂ O ₃ . At this time, the dielectric layer may be formed through various methods such as PVD, CVD, ALD, and the like.

Specifically, in the case of HfO ₂ , after forming the Hf metal layer by sputtering, HfO ₂ may be formed through oxidation. In particular, when heat treatment is performed at a high temperature together with oxidation, the crystal structure changes from tetragonal to monoclinic as the heat treatment temperature increases, and a polycrystalline structure may be formed at a higher temperature.

The dielectric thus formed forms the second pattern 114-2 through a patterning method. Such patterning can be easily implemented through a dry etching method such as reactive ion etching or a wet etching method.

Next, after forming a mask on the second pattern 114-2, a first pattern 114-1 made of a transparent conductive oxide is formed in a region between the second patterns 114-2.

In the present invention, the first patterns 114-1 are formed on the second patterns 114-2 and the second conductive layer 113-2 using a generally well-known sputtering method, more specifically, RF magnetron sputtering. was formed. In the present invention, FTO (Fluorine Tin Oxide) or AZO (Aluminum doped Zinc Oxide) is used for the first patterns 114 - 1 , but the material is not necessarily limited thereto. In addition, various transparent conductive oxides, metallic materials, and conductive polymers may also be used.

In this case, the first patterns 114-1 preferably have the same thickness as the second patterns 114-2, but are not necessarily limited thereto. Unlike this, the first patterns 114-1 may be thicker than the second patterns 114-2.

In the method of FIG. 9 , even if the transparent conductive oxide for forming the first patterns 114-1 to be formed later covers all of the existing second patterns 114-2, only the light transmittance partially decreases. Therefore, the precision of the mask covering the second patterns 114-2 does not have to be high. Therefore, the method of FIG. 9 has an additional advantage of having a large process margin, that is, a process window.

Meanwhile, unlike FIG. 9, FIG. 10 illustrates that a pattern can be formed on the intermediate layer 114 in the present invention by another method.

First, as shown in FIG. 10 , a transparent conductive oxide layer is formed on the second conductive layer 112-2. For the transparent conductive oxide layer, as shown in FIG. 9 , various transparent conductive oxides, metallic materials, and conductive polymers may be used.

The transparent conductive oxide layer thus formed forms the first pattern 114-1 through a patterning method. Such patterning can be easily implemented through a dry etching method such as reactive ion etching or a wet etching method.

Next, after forming a mask on the first patterns 114-1, second patterns 114-2 made of a dielectric material are formed in a region between the first patterns 114-1.

However, unlike the method of FIG. 9, in the method of FIG. 10, if the second patterns 114-2 cover even the first patterns 114-1, the first solar cell 110 and the second There is a problem that the solar cell 120 cannot be electrically connected. For this reason, the method of FIG. 10 requires higher precision of a mask for film formation than the method of FIG. 9 .

Meanwhile, unlike the above two examples, FIG. 11 illustrates that a pattern can be formed on the intermediate layer 114 in the present invention by another method.

11 is different from the method in FIGS. 9 and 10 in that the crystalline silicon substrate 111 is a flat substrate that is not patterned.

In FIG. 11 exemplarily, a dielectric layer is first formed on the second conductive layer 112-2. Of course, it is okay to first form a transparent conductive oxide layer instead of a dielectric layer on the second conductive layer 113-2. In this case, the dielectric layer deposition method in FIG. 11 and the deposition method in FIGS. 9 and 10 may apply the same methods.

Next, second patterns 114 - 2 are formed on the formed dielectric layer through a dry etching method or a wet etching method in the same manner as in FIGS. 9 and 10 .

Afterwards, in FIG. 11, unlike the method in FIGS. 9 and 10, a transparent conductive oxide layer is formed on the second conductive layer 112-2 and the second conductive layer 112-2 without forming a mask on the second patterns 114-2. It is entirely formed over the patterns 114-2.

Then, a portion of the transparent conductive oxide layer thus formed is removed in the thickness direction through physical polishing or chemical mechanical polishing (CMP), and as a result, the first patterns 114-1 and the second patterns ( An intermediate layer 114 made of 114-2) is formed.

Unlike the methods of FIGS. 9 and 10 , the method of FIG. 11 is simpler in the process because it does not use a mask in the deposition process, and furthermore, has advantages in that patterns can be formed more easily through polishing.

In the perovskite solar cell 120 and the tandem solar cell 100 including the perovskite solar cell 120 of the present invention, a first conductivity type charge transport layer 121 is formed on the intermediate layer 114 (FIG. 12).

If the first conductivity-type charge transport layer 121 is an electron transport layer, by using the PECVD process described above, at least one gas selected from the group consisting of SiH ₄ , Si ₂ H ₆ , SiHCl ₃ and SiH ₂ Cl _{2 and} H ₂ gas, and PH ₃ gas as a dopant gas as a reactant. At this time, the temperature and pressure conditions of the PECVD process can be said to be the same as the PECVD conditions of the amorphous intrinsic silicon layer. Accordingly, n-type amorphous silicon (na-Si) is deposited on the first conductivity-type charge transport layer 121 according to the process conditions described above.

Unlike this, of course, when the first conductivity-type charge transport layer 121 in the present invention is an electron transport layer, it may be formed by including one or a mixture of two or more of TiO ₂ , ZnO, SnO ₂ , CdS, PCBM, or C ₆₀ . there is. Among them, in the case of C ₆₀ , a fullerene derivative containing C ₆₀ is dissolved in a solvent, spin-coated for 10 to 30 seconds using a spin coating method, and maintained at room temperature for 1 to 3 hours to form an electron transport layer.

On the other hand, when the first conductivity-type charge transport layer 121 is a hole transport layer, at least one gas selected from the group consisting of SiH ₄ , Si ₂ H ₆ , SiHCl ₃ and SiH ₂ Cl _{2 and} H using the PECVD process described above. ₂ gas, and B ₂ H ₆ gas as a dopant gas as a reactant. At this time, the temperature and pressure conditions of the PECVD process can be said to be the same as the PECVD conditions of the amorphous intrinsic silicon layer. Accordingly, the first conductivity-type charge transport layer 121 of the present invention is deposited with p-type amorphous silicon (pa-Si) under these process conditions.

In addition, the hole transport layer in the present invention may be coated with an organic hole transport layer such as Spiro-MeOTAD using a solution process. Specifically, the Spiro-MeOTAD coating solution uses chlorobenzene as a solvent, in which 4-tert-butyl pyridine and lithium bis (trifluoromethanesulfonyl) imide [lithium bis( trifluoromethanesulfonyl)imide] solution was added. Thereafter, the solution is immersed on the substrate on which the perovskite layer is formed, rotated at 3,000 rpm for 30 seconds, and then dried.

Next, a perovskite absorption layer 122 is formed on the first conductivity type charge transport layer 121 (FIG. 13).

As the material of the perovskite absorption layer 122 in the present invention, all so-called methylamminium (MA)-based or formamidinium (FA)-based perovskite compounds that are currently widely used can be used. In addition, as a method of forming the perovskite absorption layer 122 in the present invention, it is possible to form a thin film process in addition to the conventional solution process.

In the present invention, as a specific embodiment, FA _{1- x} Cs _x PbBr _y I _{3 -y} (where 0 ≤ x ≤ 1, 0 ≤ y ≤ 3) is formed on the first conductivity type charge transfer layer 121 again ) component perovskite absorption layer 122 was formed.

In the present invention, an inorganic layer is first coated on the first conductivity type charge transfer layer 121 . The inorganic layer in the present invention was prepared by a solution method using PbI ₂ . First, a PbI ₂ solution was prepared by dissolving 4 mmol of PbI ₂ (Sigma-Aldrich, 99%) in 4 ml of N,N-dimethylformamide (DMF) (Sigma-Aldrich, 99.8%). Then, 40 ml of the PbI ₂ solution was rotated at a speed of 500 to 5,000 rpm for 30 seconds on the substrate on which the first conductivity type charge transfer layer 121 was formed using a spin coating method to coat the inorganic layer. Then, the substrate coated with the inorganic layer was dried at 100° C. for 15 minutes.

Next, an organic material layer is coated on the inorganic material layer. The organic layer was immersed in a 0.01 g/ml (CH(NH ₂ ) ₂ )Br solution in 2-propanol (Sigma-Aldrich, 99.5%), and then the substrate on which the inorganic layer was formed was immersed for 30 seconds at a maximum of 3,000 rpm. After rotating for 15 minutes at 100 ℃ was dried.

Meanwhile, the perovskite absorption layer 122 in the present invention is formed by physical vapor deposition or chemical vapor deposition using sputtering or electron beam, in addition to the above solution process. At this time, the perovskite absorber layer may be formed by either single step deposition or sequential step deposition, but due to the difficulty of manufacturing a uniform thin film in a single step, the sequential step is more desirable.

After forming the perovskite absorption layer 122 as described above, in order to convert it into a perovskite material, a post-heat treatment process is performed in the present invention. The post-heat treatment process is performed within about 3 hours in a temperature range of room temperature to 200 °C. The lower limit of the post-heat treatment temperature is not particularly limited, and if it is higher than 200, the polymer material, which is the perovskite absorption layer, may be thermally degraded. In addition, in the case of the deposition process, each precursor layer may be thermally decomposed or a compositional change may occur due to thermal decomposition before the precursor layers react with each other to form the perovskite layer.

Next, as shown in FIG. 14 , a second conductivity type charge transport layer 123 is formed on the perovskite absorption layer 122 . As described above, the second conductivity type charge transport layer 123 has a conductivity type of opposite polarity to that of the first conductivity type charge transport layer 121 .

After forming the second conductivity type charge transfer layer 123 in this way, in the present invention, a front transparent electrode 125 for the second electrode 130 is formed (FIG. 15).

At this time, the transparent electrode layer 125 is formed on the entire upper surface of the perovskite solar cell 120 and serves to collect electric charges generated in the perovskite solar cell 120 . The transparent electrode layer 125 may be implemented with various transparent conductive materials. That is, as the transparent conductive material, the same material as that of the intermediate layer 114 may be used.

At this time, the grid electrode 126 of the second electrode 130 is disposed on the front transparent electrode layer 125 and is disposed in a partial area of the transparent electrode layer 125 .

The grid electrode 126 of the second electrode 130 may be manufactured by selectively applying a first electrode paste that does not include a glass frit and then firing at a low temperature at a second temperature. Here, the second electrode paste may include metal particles and an organic material that is a binder for low-temperature firing, and the second electrode paste does not include a glass frit. In particular, the second temperature may be 250 or less, more specifically 100 to 200.

As described above, the grid electrode 116 of the first electrode 140 and the grid electrode 126 of the second electrode 130 form the grid electrode 126 of the second electrode 130 at the same time. Alternatively, the second electrode 130 may be formed after forming the perovskite solar cell after forming the grid electrode 116 of the first electrode 140 . Meanwhile, if the grid electrode 116 of the first electrode 140 and the grid electrode 126 of the second electrode 130 are formed at the same time, the grid electrode 116 of the first electrode 140 and the second electrode All of the grid electrodes 126 of (130) are formed by a low-temperature firing process of 250°C or less.

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 (14)

a first solar cell;
a second solar cell positioned on the first solar cell;
Including; an intermediate layer positioned between the first solar cell and the second solar cell,
The intermediate layer includes first patterns made of an electrically conductive material;
second patterns disposed between the first patterns and made of a dielectric material (high K);
including,
The tandem solar cell, characterized in that the first patterns and the second patterns are located alternately.
According to claim 1,
The electrically conductive material is a transparent conductive oxide, a carbonaceous conductive material, or a metallic material;
A tandem solar cell characterized by
According to claim 1,
The dielectric is one or more of ZrO ₂ , HfO ₂ , Y ₂ O ₃ ;
A tandem solar cell characterized by
delete According to claim 1,
The thickness of the intermediate layer is 10 to 40 ㎚;
A tandem solar cell characterized by
a first solar cell;
a second solar cell positioned on the first solar cell;
Including; an intermediate layer positioned between the first solar cell and the second solar cell,
The intermediate layer includes first patterns made of an electrically conductive material;
second patterns disposed between the first patterns and made of a dielectric material (high K);
including,
an area ratio of the first patterns and the second patterns is 30:70 to 70:30;
A tandem solar cell characterized by
a first solar cell;
a second solar cell positioned on the first solar cell;
Including; an intermediate layer positioned between the first solar cell and the second solar cell,
The intermediate layer includes first patterns made of an electrically conductive material;
second patterns disposed between the first patterns and made of a dielectric material (high K);
including,
The average width of the first patterns and the second patterns is within 10 ~ 300㎛;
A tandem solar cell characterized by
According to claim 1,
a bandgap of the second solar cell larger than that of the first solar cell;
A tandem solar cell characterized by
According to claim 1,
The first solar cell may include a substrate;
a first conductive layer positioned on a first surface of the substrate;
a second conductive layer positioned on a second surface of the substrate;
A tandem solar cell comprising a.
According to claim 9,
The first solar cell may include a first passivation layer positioned between the substrate and the first conductive layer;
The first solar cell may include a second passivation layer positioned between the substrate and the second conductive layer;
A tandem solar cell comprising a.
According to claim 9,
that the substrate and the first conductivity type layer have the same conductivity type;
A tandem solar cell characterized by
According to claim 9,
The substrate and the second conductivity type layer have the same conductivity type;
A tandem solar cell characterized by
According to claim 1,
The second solar cell may include a first conductivity type charge transport layer;
a perovskite absorption layer positioned on the first conductivity type charge transport layer;
a second conductivity-type charge transport layer positioned on the perovskite absorption layer;
A tandem solar cell comprising a.
According to claim 13,
The perovskite absorbing layer includes FA _{1- x} Cs _x PbBr _y I _{3 -y} ;
A tandem solar cell characterized by
(However, 0 ≤ x ≤ 1, 0 ≤ y ≤ 3)

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