WO2023080585A1 - Solar cell and solar cell module comprising same - Google Patents

Abstract

Disclosed are a solar cell and a solar cell module comprising same, the solar cell comprising a lower cell (100), a functional layer (200) disposed on the lower cell, and an upper cell (300) disposed on the functional layer, wherein the upper cell includes: a first upper charge transport layer (310) disposed on the upper surface of the functional layer; an insulation layer (320) disposed on the upper surface of the first upper charge transport layer; an electrode (330) disposed on the upper surface of the insulation layer; a second upper charge transport layer (340) disposed on the upper surface of the electrode; an upper electrode (350) disposed to neighbor the second upper charge transport layer on the upper surface of the electrode; an upper absorption layer (360) disposed on the second upper charge transport layer; and a plurality of through parts penetrating through the insulation layer, the electrode and the second upper charge transport layer, and a portion of lower surface of the upper absorption layer is in contact with the first upper charge transport layer through the through parts.

Description

Solar cell and solar cell module including the same

The present invention relates to a solar cell and a solar cell module including the same. Specifically, the present invention arranges the electrode of the upper cell, the electron transport layer, and the hole transport layer on the back side, but uses a surface electrode structure containing hexagonal holes for effective charge collection and prevention of shunt generation, and between the electron/hole transport layers. It relates to a solar cell characterized in that an insulator is inserted and connected to an upper layer of a lower cell and a solar cell module including the same.

The present invention is a climate change response technology development (R & D) of the Ministry of Science and ICT (Task identification number: 1711131262, research management specialized institution: Korea Research Foundation, research project name: commercial silicon-based wide bandgap perovskite multi-junction solar cell element Technology development, host organization: Korea University Industry-University Cooperation Foundation, research period: 2021.01.20 ~ 2022.01.19, contribution rate: 1/2).

In addition, the present invention is based on individual basic research (Ministry of Science and ICT) (R & D) of the Ministry of Science and ICT (Task identification number: 1711131804, research management specialized institution: National Research Foundation, research project name: Development of nanostructured thin films for high voltage stress reduction and It was derived from a study conducted as part of the PID-free Perovskite development, host organization: Korea University Industry-University Cooperation Foundation, research period: 2021.03.01 ~ 2022.02.28, contribution rate: 1/2).

Meanwhile, there is no property interest of the Korean government in any aspect of the present invention.

The problem of global warming is intensifying worldwide. In order to overcome this, in 2015, the world signed the Paris Agreement on Climate Change to keep the global average temperature rise below 2 degrees. Therefore, in order to prevent global warming, it is essential to reduce the use of existing fossil energy and develop new renewable energy that can replace it.

Renewable energy is energy that is used by recycling existing fossil fuels or converting renewable energy, and includes solar energy, geothermal energy, ocean energy, bioenergy, and the like.

Among them, solar energy and sunlight have the advantage that they are pollution-free, unlimited, and can be used anywhere on the earth. A solar cell was developed to utilize this, and is a device that converts light energy generated from the sun into electrical energy by using a photovoltaic effect.

Various solar cells using organic, inorganic, and organic-inorganic hybrids have been developed, but the use of power generated using solar cells among the total power production is still low. This is because the unit cost of solar cell power generation is higher than the cost of general electricity produced using fossil fuels. Solar cell efficiency is an important factor in determining the unit cost of solar cell power generation, and improving solar cell efficiency is important to increase price competitiveness.

Recently, the development of a silicon solar cell with a rate of 26% or more has been successfully developed and is showing steady growth.

In addition to crystalline silicon solar cells, the spectral conversion efficiency of single junction solar cells using perovskite, CIGS, α-Si, GaAs, CdTe, etc. as the light absorption layer was also researched and developed. approaching the limit.

Therefore, in order to overcome the theoretical efficiency limit of the single junction solar cell, a lot of research is being conducted to develop a multi-junction solar cell that physically and electrically connects two or more types of solar cells to drive.

For example, when a double junction solar cell is manufactured using a perovskite solar cell and a silicon solar cell, it is expected to theoretically achieve a photoelectric conversion efficiency of up to about 46%.

If the development of multi-junction solar cell technology develops and a large efficiency increase can be achieved at the level of the existing process unit price, the price competitiveness of the solar cell can be greatly increased.

Since an upper cell and a lower cell are electrically connected in series in a multi-junction solar cell, it is important to maximize the amount of current generated in the upper cell and the lower cell and to produce the same amount of current.

Researches that have existed so far have focused on adjusting the band gap of the upper cell, adjusting the thickness of the components of the multi-junction solar cell, inserting an antireflection film, or generating light diffraction in order to match the current of the multi-junction solar cell. Methods such as inserting a layer are being studied.

However, in the case of the structure of multi-junction solar cells currently being developed, in addition to the light absorption layer that absorbs light and generates current, an electron transport layer, a hole transport layer, an intermediate layer, a transparent electrode, a sputter damage prevention layer, a recombination layer, etc. Since it exists vertically for battery driving, there is light loss due to parasitic absorption.

In order to solve the above problems and maximize the photocurrent and photoelectric conversion efficiency of multi-junction solar cells, research is being conducted on introducing a back electrode structure to the top cell, but since the back electrode structure applied to the top cell involves fine patterning technology, , there is a high possibility of disconnection of the electron/hole transport layer and the electrode when fabricated linearly as in the existing literature.

In addition, when the back electrode structure is fabricated on the same plane, there is a high possibility of electric shunt due to direct contact between the electron/hole transport layer and the electrode. Accordingly, when the back electrode structure is introduced to a multi-junction solar cell, the effect of disconnection is minimized. There is a need to develop a structure of an intermediate electrode type multi-junction solar cell that is less received, is effective in charge collection, and can prevent the occurrence of electrical shunt.

In the present invention, in manufacturing a multi-junction solar cell, light absorption of the upper cell can be maximized by placing an electrode on one side of the upper cell in the form of an intermediate electrode between the upper cell and the lower cell, rather than on the uppermost end surface, and the light absorption layer It is possible to minimize parasitic absorption in which other constituent layers of the solar cell absorb light, maximize light transmission of the upper cell to maximize light absorption of the rear solar cell, and optimize photocurrent matching between the upper and lower cells. And it is an object of the present invention to provide a solar cell capable of maximizing and a solar cell module including the same.

In addition, the present invention can minimize the effect of electron/hole transport layer and electrode disconnection that may occur during the process by using surface electrodes in which hexagons are regularly arranged and removed for effective charge collection, and additionally, the two rear surfaces of the upper cell An object of the present invention is to provide a solar cell and a solar cell module including the same capable of preventing electric shunt between the two by inserting an insulating film between electrodes and not placing them on the same plane.

In addition, the present invention can maximize the photoelectric conversion efficiency by maximizing not only the photocurrent but also the open-circuit voltage of the multi-junction solar cell. In addition, by placing one electrode of the upper cell between the upper cell and the lower cell, not the uppermost surface of the upper cell, the upper cell can be operated at a high temperature of 200 ~ 300 °C, which is essential for the module process that requires electrical interconnection of single solar cells. It is possible to manufacture a multi-junction solar cell module without exposing it.

In addition, the present invention can maximize the photocurrent and photoelectric conversion efficiency of the multi-junction solar cell, and electrically interconnect the single solar cells by changing the electrode structure of one side of the solar cell instead of the uppermost surface of the upper cell. An object of the present invention is to provide a solar cell capable of manufacturing a multi-junction solar cell module without exposing an upper cell to a high temperature of 200 to 300 ° C, which is essential for a module process, and a solar cell module including the same.

On the other hand, the technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned are clearly understood by those skilled in the art from the description below. It could be.

A solar cell according to an embodiment of the present invention includes a lower cell; a functional layer disposed on the lower cell; and an upper cell disposed on the functional layer. The upper cell includes an upper first charge transport layer disposed on the upper surface of the functional layer, an insulating layer disposed on the upper first charge transport layer, an electrode disposed on the upper surface of the insulating layer, and an upper first charge transport layer disposed on the upper surface of the electrode. 2 charge transport layer, an upper electrode disposed adjacent to the upper second charge transport layer on the upper surface of the electrode, an upper absorption layer disposed on the upper second charge transport layer, and passing through the insulating layer, the electrode, and the upper second charge transport layer A plurality of through portions may be included, and a portion of a lower surface of the upper absorption layer may come into contact with the upper first charge transport layer through the through portions.

The through part may include a plurality of first through holes disposed in the insulating layer; a plurality of second through holes disposed on the electrode to communicate with each of the plurality of first through holes; and a plurality of third through holes disposed in the upper second charge transport layer to communicate with each of the plurality of second through holes.

The upper electrode may be exposed to the outside of the upper absorption layer.

The upper electrode may be disposed on one side of the functional layer, and the upper second charge transport layer and the upper absorption layer may be disposed on the other side of the functional layer.

Each of the first through hole, the second through hole, and the third through hole may have a circular or polygonal cross section.

On the same surface, an area of the third through hole to an area of the upper second charge transport layer may have a range of 0.33:1 to 3:1.

The lower cell includes a lower electrode, a reflective layer disposed on the upper surface of the lower electrode, a lower passivation layer disposed on the upper surface of the reflective layer, a lower functional layer disposed on the upper surface of the lower passivation layer, and a lower absorption layer disposed on the upper surface of the lower functional layer. can do.

The lower absorption layer may be a p-type semiconductor or an n-type semiconductor, and the functional layer may be an n-type semiconductor or a p-type semiconductor corresponding to the lower absorption layer.

In addition, the lower absorption layer may be a silicon semiconductor, the functional layer may be a p-n junction layer, and the lower functional layer may be a BSF.

In addition, the upper absorption layer may absorb medium and short wavelengths to generate electron-hole pairs, and the lower absorption layer may absorb medium and long wavelengths to generate electron-hole pairs.

In addition, a solar cell module according to another embodiment of the present invention includes a first solar cell; and a second solar cell electrically connected to the first solar cell. wherein each of the first solar cell and the second solar cell includes a lower cell, a functional layer disposed on the lower cell, and an upper cell disposed on the functional layer, wherein the upper cell comprises the An upper first charge transport layer disposed on the upper surface of the functional layer, an insulating layer disposed on the upper surface of the upper first charge transport layer, an electrode disposed on the upper surface of the insulating layer, an upper second charge transport layer disposed on the upper surface of the electrode, and the upper second charge layer disposed on the upper surface of the functional layer. An upper absorption layer disposed on the transport layer, and a plurality of through portions penetrating the insulating layer, the electrode, and the upper second charge transport layer, wherein a portion of the lower surface of the upper absorption layer is aligned with the upper first charge transport layer through the through portion. can be reached

The upper cell of the second solar cell may further include an upper electrode disposed adjacent to the upper second charge transport layer on the upper surface of the electrode.

An upper absorption layer of an upper cell of the first solar cell may be spaced apart from the second solar cell.

According to an embodiment of the present invention, light absorption in the upper cell can be maximized, parasitic absorption in which light is absorbed by other component layers other than the light absorbing layer can be minimized, and light transmission of the upper cell can be maximized to maximize the rear sun. Light absorption of the battery can be maximized, and photocurrent matching between the upper cell and the lower cell can be optimized and maximized.

In addition, according to an embodiment of the present invention, photocurrent and photoelectric conversion efficiency of a multi-junction solar cell can be maximized, and single solar cells can be formed by changing the electrode structure of one solar cell instead of the uppermost surface of the upper cell. A multi-junction solar cell module can be manufactured without exposing the upper cell to the high temperature of 200 to 300 °C, which is essential for the module process that needs to be electrically interconnected.

On the other hand, the effects obtainable in the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description below. There will be.

1 is a perspective view showing a solar cell according to an embodiment of the present invention;

2 is an exemplary view showing a movement path of light according to wavelength in a solar cell according to an embodiment of the present invention;

3 is a perspective view in which an upper absorber layer is removed from a solar cell according to an embodiment of the present invention;

4 is a top view of a solar cell according to an embodiment of the present invention in which an upper absorption layer is removed;

5 is a cross-sectional view taken along line A-A' of FIG. 1, in which the upper absorption layer is removed;

6 is a cross-sectional view along the line A-A' of FIG. 1;

7 is a cross-sectional view showing a solar cell module according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in more detail with reference to the accompanying drawings. Embodiments of the present invention may be modified in various forms, and the scope of the present invention should not be construed as being limited to the following examples. This embodiment is provided to more completely explain the present invention to those skilled in the art. Accordingly, the shapes of elements in the figures are exaggerated to emphasize clearer description.

The composition of the present invention for clarifying the solution to the problem to be solved by the present invention will be described in detail with reference to the accompanying drawings based on a preferred embodiment of the present invention, but the same reference numerals are assigned to the components of the drawings. For components, even if they are on other drawings, the same reference numerals have been given, and it is made clear in advance that components of other drawings can be cited if necessary in the description of the drawings.

1 is a perspective view showing a solar cell according to an embodiment of the present invention, FIG. 2 is an exemplary view showing a movement path of light according to wavelength in a solar cell according to an embodiment of the present invention, and FIG. A perspective view of a solar cell according to an embodiment of which the upper absorption layer is removed, FIG. 4 is a top view of a solar cell according to an embodiment of the present invention in which the upper absorption layer is removed, and FIG. In , the upper absorption layer is removed, and FIG. 6 is a cross-sectional view taken along the line AA' of FIG. 1 .

1 to 6 together, a solar cell according to an embodiment of the present invention may include a lower cell 100, a functional layer 200, and an upper cell 300.

Here, the solar cell according to an embodiment of the present invention includes a silicon solar cell 100 including an absorption layer having a relatively small band gap and a perovskite solar cell including an absorption layer having a relatively large band gap ( 300) has a structure of a two-terminal tandem solar cell directly tunnel-junctioned through the functional layer 200.

Accordingly, light in the short wavelength region among light incident to the solar cell according to an embodiment of the present invention is absorbed by the perovskite solar cell 300 disposed thereon to generate charge, and the perovskite solar cell 300 generates electric charge. Light in the long-wavelength region passing through the battery cell 300 is absorbed by the silicon solar cell or other organic, inorganic, or mixed organic and inorganic solar cell 100 disposed below to generate charge.

The solar cell according to an embodiment of the present invention having the above-described structure absorbs light in the medium and short wavelength regions in the perovskite solar cell 300 disposed on the upper portion to generate power, and the silicon solar cell disposed on the lower portion By absorbing and generating light in the medium and long wavelength regions in the battery cell 100, the threshold wavelength can be moved to the long wavelength side, and as a result, there is an advantage in that the wavelength band absorbed by the entire solar cell can be widened.

Meanwhile, the lower cell 100 may be implemented as a heterojunction silicon solar cell, a homojunction silicon solar cell, or a solar cell in which organic materials, inorganic materials, or organic and inorganic materials are mixed.

The lower cell 100 may include a lower electrode 110 , a reflective layer 120 , a lower passivation layer 130 , a lower functional layer 140 and a lower absorption layer 150 .

Meanwhile, although not shown, at least one of the lower electrode 110, the reflective layer 120, the lower passivation layer 130, the lower functional layer 140, and the lower absorption layer 150 may have a texture having a concavo-convex structure. .

The lower electrode 110 may be a metal or a metal alloy. The lower electrode 110 is at least one selected from molybdenum (Mo), aluminum (Al), silver (Ag), gold (Au), platinum (Pt), copper (Cu), nickel (Ni), and carbon (C). may contain substances.

Meanwhile, the lower electrode 110 may perform a function of reflecting light incident thereon so that it does not escape to the outside.

Also, the lower electrode 110 may collect holes or electrons.

The reflective layer 120 may be directly disposed on the upper surface of the lower electrode 110 and serves to increase photoelectric conversion efficiency by increasing the path of light incident thereon.

The lower passivation layer 130 may be formed of a light-transmitting insulating film, and an insulating film based on an oxide film or a nitride film may be used.

The lower functional layer 140 may serve to return specific charges to the absorption layer or function as an electron transport layer or a hole transport layer according to the semiconductor type of the lower absorption layer 150 .

When the lower functional layer 140 is a hole transport layer, the hole transport layer is PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)), polythiophenylenevinylene, It may be polyvinylcarbazole, poly-p-phenylenevinylene, and derivatives thereof. However, it is not limited thereto, and various types of organic materials may be used. Also, p-type doped metal oxide semiconductors such as molybdenum oxide, vanadium oxide, or tungsten oxide may be used.

In addition, when the lower functional layer 140 is an electron transport layer, this electron transport layer is fullerene (C60, C70, C80) or fullerene derivative PCBM ([6,6]-phenyl-C61 butyric acid methyl ester) (PCBM (C60 ), PCBM (C70), PCBM (C80)). However, it is not limited thereto, and various types of organic materials may be used. In addition, n-type doped metal oxide semiconductors such as titanium oxide (TiOx) or zinc oxide (ZnO) may be used.

Meanwhile, when the lower cell 100 is a silicon-based solar cell, the lower functional layer 140 serves as a back surface field (BSF) that increases the charge collection probability by forming an electric field on the rear surface of the lower absorption layer 150. can be done

The lower absorption layer 150 may include, for example, amorphous silicon, microcrystalline silicon, amorphous silicon germanium, microcrystalline silicon germanium, an organic material, or a mixture of an organic material and an inorganic material.

The lower absorbing layer 150 may have a smaller energy bandgap than the upper absorbing layer 360 of the upper cell 300 and may absorb medium and long wavelength light.

Here, the wavelength band of the medium wavelength may be 500 nm to 900 nm, and the wavelength band of the long wavelength may be 700 nm to 1,200 nm.

The lower absorption layer 150 absorbs long-wavelength light irradiated onto the solar cell and may form electron-hole pairs in an excited state, that is, excitons.

The functional layer 200 is disposed on the lower cell 100 and may be disposed on the upper surface of the lower absorption layer 150 .

That is, the functional layer 200 may be disposed between the lower cell 100 and the upper cell 300 .

The functional layer 200 may function as a recombination layer in which electrons (holes) transferred from the lower absorption layer 150 and holes (electrons) transferred from the upper absorption layer 360 meet and recombine.

That is, in the functional layer 200, electrons of the lower absorption layer 150 and holes of the upper absorption layer 360 or holes of the lower absorption layer 150 and electrons of the upper absorption layer 360 may meet and recombine.

When a transparent electrode is used for the functional layer 200, it may be indium tin oxide (ITO). However, it is not limited thereto, and may be formed as a transparent conductive layer using a material such as aluminum-doped zinc oxide (AZO).

The upper cell 300 is disposed on the functional layer 200 and may be implemented as a perovskite solar cell.

The upper cell 300 may include an upper first charge transport layer 310, an insulating layer 320, an electrode 330, an upper second charge transport layer 340, an upper electrode 350, and an upper absorption layer 360. there is.

Preferably, the upper first charge transport layer 310 is disposed on the entire upper surface of the functional layer 200 . Here, the upper first charge transport layer 310 is preferably formed such that its top and bottom surfaces have the same shape and width as those of the functional layer 200 .

The upper first charge transport layer 310 may function as an electron transport layer or a hole transport layer according to the semiconductor type of the upper absorption layer 360 .

When the upper first charge transport layer 310 is a hole transport layer, the hole transport layer is PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)), polythiophenylenevinylene ), polyvinylcarbazole, poly-p-phenylenevinylene, Poly(3-hexylthiophene-2,5-diyl) (P3HT), Poly[bis(4-phenyl)(2 ,4,6-trimethylphenyl)amine] (PTAA), 9′-spirobi[9H-fluorene]-2,2′,7,7′′-tetramine (Spiro-MeOTAD), and derivatives thereof. However, it is not limited thereto, and various types of organic materials may be used. Also, p-type doped metal oxide semiconductors such as molybdenum oxide, vanadium oxide, tungsten oxide and nickel oxide may be used.

In addition, when the upper first charge transport layer 310 is an electron transport layer, this electron transport layer is fullerene (C60, C70, C80) or fullerene derivative PCBM ([6,6]-phenyl-C61 butyric acid methyl ester) (PCBM) (C60), PCBM (C70), PCBM (C80)). However, it is not limited thereto, and various types of organic materials may be used. In addition, n-type doped metal oxide semiconductors such as titanium oxide (TiOx), zinc oxide (ZnO), or tin oxide (SnOx) may be used.

The insulating layer 320 may be disposed on the entire upper surface of the upper first charge transport layer 310 to cover the upper first charge transport layer 310 . The insulating layer 320 may be formed of a light-transmitting insulating film, and an insulating film based on an oxide film or a nitride film may be used.

Here, the upper first charge transport layer 310 is preferably formed on the functional layer using an organic or inorganic material having conductivity by spin coating, dip coating, drop casting, inkjet printing, screen printing, sputtering, or thermal evaporation. do.

Meanwhile, organic or inorganic materials that may be used for the upper first charge transport layer 310 may include conductive metals such as gold or silver, metal nanoparticles, metal oxides, or conductive polymers. The conductive polymer is preferably at least one selected from the group consisting of poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS), polyaniline, and polypyrrole.

Meanwhile, the insulating layer 320 may include a plurality of first through holes 321 disposed to penetrate upper and lower surfaces.

For uniform charge collection, the first through holes 321 are preferably arranged while maintaining the same size and spacing. Therefore, the cross section of the first through hole 321 is preferably formed in a hexagonal shape.

However, the cross section of the first through hole 321 may be formed in a circle or polygon as well as a hexagon.

The electrode 330 is preferably disposed on the entire surface of the insulating layer 320, and may include a plurality of second through holes 331 disposed to penetrate the upper and lower surfaces.

Here, the electrode 330 is preferably formed to have the same shape and width as the insulating layer 320 .

In addition, each of the plurality of second through holes 331 may correspond to each of the plurality of first through holes 321 and communicate with each other.

Here, 'corresponding' means that the positions and sizes of the first through holes 321 and the second through holes 331 are the same or similar to each other.

Meanwhile, the area of the third through hole 341 to the area of the second upper charge transport layer 340 located at the topmost position on the same surface except for the upper absorption layer 360 preferably has a range of 0.33:1 to 3:1. do.

Here, the area of the upper second charge transport layer 340 may be defined as the area of the area where the third through hole 341 is not formed.

Meanwhile, since the upper first charge transport layer 310 is exposed with the same size as the through portions 321, 331, and 341, the area ratio of the upper second charge transport layer 340 and the area of the third through hole 341 Means the ratio of the area in which holes (electrons) and electrons (holes) can be collected, respectively.

Here, when the area of the third through hole 341 to the area of the upper second charge transport layer 340 is less than 0.33:1, the ratio of the area where holes (electrons) can be collected is excessively small compared to the area of electrons (holes), resulting in device performance. When the area of the third through hole 341 to the area of the upper second charge transport layer 340 exceeds 3:1, the ratio of the area where electrons (holes) can be collected is the hole (electron) It is excessively small compared to , and similarly, there is a problem of causing deterioration in device performance.

Meanwhile, the electrode 330 may be a metal or a metal alloy. The electrode 330 is at least one material selected from molybdenum (Mo), aluminum (Al), silver (Ag), gold (Au), platinum (Pt), copper (Cu), carbon (C), and nickel (Ni). can include The electrode 330 may also be formed as a transparent conductive layer using materials such as indium tin oxide (ITO) and aluminum-doped zinc oxide (AZO).

Here, the upper electrode 350 may be disposed on the electrode 330 in a region where the second upper charge transport layer 340 is not disposed.

The upper second charge transport layer 340 is preferably disposed on the other side of the upper surface of the electrode 330 and may include a plurality of third through holes 341 disposed to penetrate the upper and lower surfaces.

In addition, each of the plurality of third through holes 341 may correspond to each of the plurality of second through holes 331 and communicate with each other.

That is, the first through hole 321 , the second through hole 331 , and the third through hole 341 correspond to each other and form one through part 321 , 331 , and 341 .

The upper second charge transport layer 340 may function as an electron transport layer or a hole transport layer according to the semiconductor type of the upper absorption layer 360 .

When the upper second charge transport layer 340 is a hole transport layer, the hole transport layer is PEDOT:PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)), polythiophenylenevinylene ), polyvinylcarbazole, poly-p-phenylenevinylene, Poly(3-hexylthiophene-2,5-diyl) (P3HT), Poly[bis(4-phenyl)(2 ,4,6-trimethylphenyl)amine] (PTAA), 9′-spirobi[9H-fluorene]-2,2′,7,7′′-tetramine (Spiro-MeOTAD), and derivatives thereof. However, it is not limited thereto, and various types of organic materials may be used. In addition, p-type doped metal oxide semiconductors such as molybdenum oxide, vanadium oxide, tungsten oxide, or nickel oxide may be used.

In addition, when the upper second charge transport layer 340 is an electron transport layer, this electron transport layer is fullerene (C60, C70, C80) or fullerene derivative PCBM ([6,6]-phenyl-C61 butyric acid methyl ester) (PCBM) (C60), PCBM (C70), PCBM (C80)). However, it is not limited thereto, and various types of organic materials may be used. In addition, n-type doped metal oxide semiconductors such as titanium oxide (TiOx), tin oxide (SnOx), or zinc oxide (ZnO) may be used.

As described above, the upper electrode 350 may be disposed on one side of the electrode 330 .

Here, the upper electrode 350 is not covered by the upper absorption layer 360 and may be exposed to the outside to provide an electrical connection path.

That is, by disposing the upper electrode 350 on one side of the solar cell rather than on the uppermost surface of the upper cell, the upper cell is not exposed to the high temperature of 200 to 300 °C, which is essential for a module process that requires electrical interconnection of single solar cells. It is possible to manufacture a multi-junction solar cell module without the need for heat damage to the upper cell.

The upper electrode 350 may be a metal or a metal alloy. The upper electrode 350 is at least one selected from molybdenum (Mo), aluminum (Al), silver (Ag), gold (Au), platinum (Pt), copper (Cu), carbon (C), and nickel (Ni). may contain substances.

The upper absorption layer 360 is disposed on top of the upper second charge transport layer 340, and a part of the lower end may pass through the through portions 321, 331, and 341 to directly contact the upper first charge transport layer 310. there is.

Meanwhile, the upper absorption layer 360 may have a larger energy bandgap than the lower absorption layer 150 of the lower cell 100 and may absorb medium and short wavelength light.

Here, the wavelength band of the medium wavelength may be 500 nm to 900 nm, and the wavelength band of the short wavelength may be 300 nm to 700 nm.

The upper absorption layer 360 absorbs short-wavelength light irradiated onto the solar cell and may form electron-hole pairs in an excited state, that is, excitons.

Here, the upper absorption layer 360 may be formed of a perovskite compound as an optically active material. Perovskite has the advantage of having a direct bandgap, an optical absorption coefficient as high as 1.5Х10 ⁴ cm ^-1 at 550 nm, excellent charge transfer characteristics, and excellent resistance to defects.

In addition, the perovskite compound has the advantage of being able to form the light absorber constituting the photoactive layer through an extremely simple, easy, and low-cost simple process of applying and drying the solution, and crystallizes spontaneously by drying the applied solution. , it is possible to form a light absorber of coarse crystal grains, and in particular, the conductivity for both electrons and holes is excellent.

This perovskite compound is ABX ₃ (A is a C1-C20 alkyl group, a monovalent metal (eg, Li, Na, Cs, Rb, etc.), a monovalent organic ammonium ion or formamidinium having a resonance structure (formamidinium, FA) or methylammonium (MA), B is a divalent metal ion, and X is a halogen ion).

That is, in the above-described solar cell structure, in manufacturing a multi-junction solar cell, the electrode 330 is placed in the form of an intermediate electrode between the upper cell and the lower cell instead of the uppermost side of the upper cell 300, The light absorption of the cell can be maximized.

In addition, it is possible to minimize parasitic absorption in which light is absorbed by other constituent layers of the solar cell other than the light absorption layer, and to maximize the light absorption of the rear solar cell by maximizing the light transmission of the upper cell, and to maximize the light absorption of the upper cell and the lower cell. It is possible to optimize and maximize the photocurrent matching of

In addition, hexagonal penetrating parts are regularly arranged for effective charge collection, and the effect of electron/hole transport layer and electrode disconnection that may occur during the process can be minimized by using a surface electrode removed from the penetrating part, and additionally, the upper cell An electrical shunt between the upper electrode 330 and the upper second charge transport layer 340 may be prevented by inserting an insulating film between the two rear electrodes.

Specifically, electrons (holes) are collected in the upper first charge transport layer 310 and holes (electrons) are collected in the upper electrode 330 and the upper second charge transport layer 340, and direct contact occurs between the two. If so, electron-space recombination and shunting may occur, resulting in deterioration in device performance. Therefore, direct contact between the two is prevented by inserting an insulating layer therebetween, thereby preventing electric shunt.

By not placing them on the same plane, electrical shunts between the two can be prevented. As a result, it is possible to maximize the photoelectric conversion efficiency by maximizing not only the photocurrent but also the open-circuit voltage of the multi-junction solar cell.

In addition, by placing the electrode of the upper cell between the upper cell and the lower cell, not the uppermost surface of the upper cell, the upper cell can be operated at a high temperature of 200 ~ 300 °C, which is essential for the module process that requires electrical interconnection of single solar cells. It is possible to manufacture a multi-junction solar cell module without exposing it.

Meanwhile, the solar cell according to the embodiment of the present invention describes a double junction solar cell in which two types of solar cells are stacked, but it can be applied to a triple or more multi-junction solar cell as well.

Hereinafter, a solar cell module according to another embodiment of the present invention will be described with reference to FIG. 7 .

7 is a cross-sectional view showing a solar cell module according to another embodiment of the present invention.

Referring to FIG. 7 , since a solar cell module according to another embodiment of the present invention has a structure in which solar cell pairs 1000 and 2000 according to an embodiment of the present invention shown in FIGS. 1 to 6 are electrically connected, the following In , a detailed description of the configuration of each solar cell 1000 or 2000 is omitted.

A solar cell module according to another embodiment of the present invention may be configured by electrically connecting the first solar cell 1000 and the second solar cell 2000 .

Meanwhile, as shown in FIG. 7 , the first solar cell 1000 and the second solar cell 2000 may be stacked with each other offset from each other. Through this, since light incident from the top can reach the first solar cell 1000 without being refracted or disturbed by the second solar cell 2000, photoelectric conversion efficiency can be maximized.

Here, the first solar cell 1000 may include a lower cell 1100 , a functional layer 1200 and an upper cell 1300 .

In addition, the lower cell 1100 may include a lower electrode 1110, a reflective layer 1120, a lower passivation layer 1130, a lower functional layer 1140, and a lower absorption layer 1150.

In addition, the upper cell 1300 may include an upper first charge transport layer 1310, an insulating layer 1320, an electrode 1330, an upper second charge transport layer 1340, and an upper absorption layer 1360.

In addition, the second solar cell 2000 may include a lower cell 2100 , a functional layer 2200 and an upper cell 2300 .

In addition, the lower cell 2100 may include a lower electrode 2110, a reflective layer 2120, a lower passivation layer 2130, a lower functional layer 2140, and a lower absorption layer 2150.

In addition, the upper cell 2300 may include an upper first charge transport layer 2310, an insulating layer 2320, an electrode 2330, an upper second charge transport layer 2340, and an upper absorption layer 2360.

Meanwhile, the lower electrode 2110 of the second solar cell 2000 may be electrically and physically connected to the electrode 1330 of the first solar cell 1000 .

Meanwhile, although not shown, an upper electrode (not shown) may be disposed on the electrode 1330, and the lower electrode 2110 of the second solar cell 2000 is electrically and electrically connected to the upper electrode of the first solar cell 1000. can be physically connected.

Here, the lower electrode 2110 of the second solar cell 2000 is physically different from the upper first charge transport layer 1310, the upper second charge transport layer 1340, and the upper absorption layer 1360 of the first solar cell 1000. It is preferable to arrange them so that they are spaced apart from each other.

Meanwhile, although not shown, the upper electrode 2340 may be removed from the second solar cell 2000, and a third solar cell (not shown) electrically and physically connected to the electrode 2330 may be disposed.

The above detailed description is illustrative of the present invention. In addition, the foregoing is intended to illustrate and describe preferred embodiments of the present invention, and the present invention can be used in various other combinations, modifications, and environments. That is, changes or modifications are possible within the scope of the concept of the invention disclosed in this specification, within the scope equivalent to the written disclosure and / or within the scope of skill or knowledge in the art. The written embodiment describes the best state for implementing the technical idea of the present invention, and various changes required in the specific application field and use of the present invention are also possible. Therefore, the above detailed description of the invention is not intended to limit the invention to the disclosed embodiments. Also, the appended claims should be construed to cover other embodiments as well.

[Description of code]

100: lower cell

200: functional layer

300: upper cell

Claims (13)

1. lower cell;

   a functional layer disposed on the lower cell; and

   an upper cell disposed on the functional layer; including,

   The upper cell is

   An upper first charge transport layer disposed on the upper surface of the functional layer;

   An insulating layer disposed on the upper surface of the first charge transport layer,

   an electrode disposed on the upper surface of the insulating layer;

   An upper second charge transport layer disposed on the upper surface of the electrode;

   An upper electrode disposed adjacent to the upper second charge transport layer on the upper surface of the electrode;

   an upper absorption layer disposed on the upper second charge transport layer; and

   A plurality of through portions penetrating the insulating layer, the electrode, and the upper second charge transport layer,

   A portion of the lower surface of the upper absorption layer contacts the upper first charge transport layer through the through-hole.
2. According to claim 1,

   the penetrating part

   a plurality of first through holes disposed in the insulating layer;

   a plurality of second through holes disposed on the electrode to communicate with each of the plurality of first through holes; and

   A solar cell comprising a plurality of third through holes disposed in the upper second charge transport layer to communicate with each of the plurality of second through holes.
3. According to claim 1,

   The solar cell wherein the upper electrode is exposed to the outside of the upper absorption layer.
4. According to claim 1,

   The upper electrode is disposed on one side on the functional layer,

   The upper second charge transport layer and the upper absorption layer are disposed on the other side of the functional layer.
5. According to claim 2,

   The solar cell of claim 1 , wherein each of the first through hole, the second through hole, and the third through hole has a circular or polygonal cross section.
6. According to claim 2,

   On the same surface, the area of the third through hole compared to the area of the upper second charge transport layer has a range of 0.33:1 to 3:1.
7. According to claim 1,

   the lower cell

   lower electrode,

   A reflective layer disposed on the upper surface of the lower electrode;

   a lower passivation layer disposed on the upper surface of the reflective layer;

   A lower functional layer disposed on the upper surface of the lower passivation layer, and

   A solar cell including a lower absorption layer disposed on an upper surface of the lower functional layer.
8. According to claim 7,

   The lower absorption layer is a p-type semiconductor or an n-type semiconductor,

   The solar cell of claim 1 , wherein the functional layer is an n-type semiconductor or a p-type semiconductor corresponding to the lower absorption layer.
9. According to claim 8,

   The lower absorption layer is a silicon semiconductor,

   The functional layer is a p-n junction layer,

   The solar cell wherein the lower functional layer is a field forming layer (BSF).
10. According to claim 7,

    the upper absorption layer absorbs medium and short wavelengths to generate electron-hole pairs;

    The lower absorption layer absorbs medium and long wavelengths to generate electron-hole pairs.
11. a first solar cell; and

    a second solar cell electrically connected to the first solar cell; including,

    Each of the first solar cell and the second solar cell,

    lower cell,

    A functional layer disposed on the lower cell, and

    Including an upper cell disposed on the functional layer,

    The upper cell is

    An upper first charge transport layer disposed on the upper surface of the functional layer;

    An insulating layer disposed on the upper surface of the first charge transport layer,

    an electrode disposed on the upper surface of the insulating layer;

    An upper second charge transport layer disposed on the upper surface of the electrode;

    an upper absorption layer disposed on the upper second charge transport layer; and

    A plurality of through portions penetrating the insulating layer, the electrode, and the upper second charge transport layer,

    A portion of the lower surface of the upper absorption layer is in contact with the upper first charge transport layer through the through-hole.
12. According to claim 11,

    The upper cell of the second solar cell,

    The solar cell module further comprises an upper electrode disposed adjacent to the upper second charge transport layer on the upper surface of the electrode.
13. According to claim 12,

    The upper absorption layer of the upper cell of the first solar cell is spaced apart from the second solar cell.

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