WO2022114268A1

WO2022114268A1 - Solar cell including perovskite

Info

Publication number: WO2022114268A1
Application number: PCT/KR2020/016957
Authority: WO
Inventors: 장윤희; 이도권; 김인호; 이하람; 정증현
Original assignee: 한국과학기술연구원
Priority date: 2020-11-26
Filing date: 2020-11-26
Publication date: 2022-06-02
Also published as: KR20220073185A; KR102478481B1

Abstract

Disclosed is a solar cell including perovskite, the solar cell comprising: a substrate; a lower transparent conductive layer, a perovskite absorption region, and an upper metal electrode, which are sequentially formed on the substrate; and an encapsulation cap structure encapsulating at least the perovskite absorption region and bonded to the substrate by means of an adhesive material, wherein the upper metal electrode extends in a first direction to pass through an end of the encapsulation cap structure, so that the electrode protrudes to the outside, and the lower transparent conductive layer is separated as stripes by an insulating region, to pull out an electrode to the outside in a second direction intersecting the first direction.

Description

Solar cell containing perovskite

The present invention relates to an encapsulation structure in a solar cell containing perovskite.

The perovskite solar cell recorded a high photoelectric conversion efficiency of 25.5% and achieved rapid development within a short period of time. It is considered to be highly probable.

Perovskite is being used as a tandem solar cell (Si/perovskite, CIGS/perovskite, perovskite/perovskite, etc.), and these perovskite tandem solar cells are expected to be commercialized in the near future, Research and mass production for the commercialization of perovskite-based tandem solar cells are being spurred.

However, even if perovskite solar cells and tandem solar cells are close to commercially available efficiencies, it is necessary to solve the problem of low durability of perovskite solar cells for commercialization.

To this end, as well as expanding the stability of the perovskite material itself, continuous research is needed on perovskite solar cell encapsulation technology for practical application.

A technology for encapsulating perovskite solar cells according to the prior art will be described. In manufacturing a solar cell, since the upper/lower electrode contact has to be made outside the encapsulation cell, the extension of the upper electrode is unavoidable. Therefore, when the upper electrode is extended, a part of the perovskite solar cell is exposed to the outside of the encapsulation cell, and as the perovskite degradation occurs in the exposed area, the efficiency of the perovskite solar cell rapidly decreases. A problem occurred.

In order to prevent this problem, if the perovskite absorption layer exposed to the outside of the encapsulation cell is removed, the upper/lower electrodes come into direct contact and a short circuit problem may occur. There is a need for research on it.

[Prior art literature]

[Patent Literature]

Korean Patent Publication No. 10-2017-0139826

It is an object of the present invention to solve a problem in that the efficiency of a perovskite solar cell is rapidly reduced as the perovskite deteriorates in a region to which the perovskite is exposed.

As a means for solving the above-described problems, an aspect of the present invention is a solar cell comprising a perovskite, the substrate; a lower transparent conductive layer, a perovskite absorption region, and an upper metal electrode sequentially formed on the substrate; and an encapsulation cap structure bonded to the substrate through an adhesive material while encapsulating at least the perovskite absorption region, wherein the upper metal electrode extends past an end of the encapsulation cap structure in a first direction to the outside. is drawn out, and the lower transparent conductive layer is a perovskite having a structure in which the lower transparent conductive layer is separated by an insulating region so as to have a strip shape in order to withdraw the electrode to the outside in a second direction intersecting the first direction It provides a solar cell comprising a.

Preferably, the encapsulation cap structure and the substrate are adhered through an adhesive material, and in order to prevent the adhesive material from permeating into the cavity area, a groove through which the adhesive material can flow is provided at a portion where the encapsulation cap structure comes into contact with the substrate has been

The perovskite absorption region may be a single cell or a tandem cell including a perovskite absorption layer.

The perovskite absorption region may have a structure connected to a plurality of cells, and in this case, a separation region is provided in the lower transparent conductive layer.

When the perovskite absorption region is a tandem cell, the recombination layer for bonding the upper cell and the lower cell is preferably formed in a smaller area than the stacked upper layer.

Preferably, the insulating region is filled with an insulating material, and the insulating material is selectively etched on the lower transparent conductive layer to a predetermined line width, and the insulating material is transferred to the etched region using a laser transfer method.

According to the present invention, there is an effect that can solve the problem that the efficiency of the perovskite solar cell rapidly decreases as the deterioration of the perovskite occurs in the area where the perovskite is exposed.

In addition, according to the encapsulation structure of the present invention, the problem of short circuit does not occur by configuring so that the upper and lower electrodes do not directly contact.

In addition, according to the encapsulation structure of the present invention, the perovskite absorption layer deterioration due to the adhesive material is prevented by including the encapsulation cap structure provided with the groove through which the adhesive material can flow.

1 is a plan view of a solar cell including perbroskite according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA′ of FIG. 1 .

3 is a view illustrating a process of forming an insulating region and filling an insulating material in the manufacturing process of FIG. 1 .

4 is a cross-sectional view of a solar cell including perbroskite according to another embodiment of the present invention.

5 is a cross-sectional view of a solar cell including perbroskite according to another embodiment of the present invention.

Advantages and features of the invention disclosed herein, and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present specification is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only the present embodiments allow the disclosure of the present specification to be complete, and those of ordinary skill in the art to which this specification belongs. It is provided to fully inform those skilled in the art (hereinafter, 'those skilled in the art') the scope of the present specification, and the scope of the present specification is only defined by the scope of the claims.

1 is a plan view of a solar cell including a perbroskite according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along line AA′ of FIG. 1 .

The perovskite solar cell includes a lower transparent conductive layer 120 stacked on the substrate 110 , and has a perovskite absorption region 150 on the lower transparent conductive layer 120 . The perovskite absorption region 150 means a stacked structure including a perovskite absorption layer, and may be a single perovskite absorption layer, or an absorption layer other than the perovskite absorption layer is added. It is also possible

The substrate 110 may be formed of a transparent material through which light may pass. For example, the substrate 110 may be formed of glass or a transparent polymer material. The transparent polymer material is polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polycarbonate (PC), polypropylene (poly propylene, PP), polyimide (poly imide, PI), triacetyl cellulose (TAC), or a copolymer thereof, and the like.

The lower transparent conductive layer 120 is a transparent conductive oxide (Transparent Conductive Oxide, TCO), for example, indium tin oxide (Indium Tin Oxide, ITO), fluorine tin oxide (FTO), zinc oxide (Zinc oxide) ), tin oxide, and the like.

For example, FIG. 2 shows a structure in which a thin film is formed in the order of a hole transport layer 150a, a metal halide perovskite 150b, an electron transport layer 150c, and a transparent electrode 150d. As the thin film deposition process, solution processes such as spin coating and blade coating, sputtering, and vacuum deposition such as thermal evaporation can be used. However, the perovskite absorption region 150 is not limited to this structure, and may be a tandem cell in which a lower cell and an upper cell are stacked. As an example of the tandem solar cell, the lower solar cell is not particularly limited, such as a thin film solar cell or a silicon solar cell, and the upper solar cell may be a perovskite solar cell.

The hole transport layer 150a is formed between the lower transparent conductive layer 120 and the perovskite material 150b, and any hole transport material applied in the technical field of the present invention may be applied without limitation, for example, PEDOT :PSS (poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)), PTAA (poly[bis(4-phenyl)(2,4,6-trimethylphenyl), P30T (poly(3- Octylthiophene)), P3DT (poly(3-decylthiophene)), TPD (N,N'-bis(3-methylphenyl)-N,N'-diphenyl-[1,1'-biphenyl]- 4,4'-diamine), P3DDT (poly (3-dodecylthiophene), polythiophenylenevinylene), polyvinylcarbazole (polyvinylcarbazole), polyparaphenylenevinylene (poly-p-phenylenevinylene) and their derivatives, spiro substances, spiro-OMeTAD (piro-MeOTAD[2,2',7,7'-tetrakis-N,N-di-p-methoxyphenyl-mine)-9,9'-spirobifluoren ]), spiro-DPVBi(Spiro-4,4'-bis 2,2-diphenylethenyl)-1,1' biphenyl), molybdenum oxide (MoO _x ), nickel oxide (NiO _x ), vanadium oxide (eg, V ₂ O ₅ ), tungsten oxide (WO _x ), etc. may be a metal oxide semiconductor.

The perovskite material 150b is a compound having a perovskite crystal structure such as CH ₃ NH _{3 PbI 3 , CH 3 NH 3} _{PbBr 3} _, _CH ₃ _NH ₃ PbI ₂ Cl, CH ₃ NH ₃ PbI ₂ Br, etc. can be formed. A method of forming the hole transport layer and the perovskite material is not particularly limited. In one embodiment, the perovskite material may be formed by applying a precursor solution of the perovskite material to the surface of the hole transport layer. For example, when the perovskite material is CH ₃ NH ₃ PbI ₃ , a mixed solution of dimethyl sulfoxide and gamma-butyrolactone in which PbI ₂ and CH ₃ NH ₃ I are dissolved is applied to the hole transport layer to CH ₃ After forming NH ₃ PbI ₃ , the perovskite material may be formed by crystallizing it.

Electron transport layer 150c, C60, C70, C71, C76, C78, C80, C82, C84, C92 PC60BM, PC61BM, PC71BM, ICBA, BCP, PC70BM, IC70BA, PC84BM, indene C60, indene C70, endohydral fullerene , perylene, PTCDA, PTCBI, BCP (bathocuproine), Bphen (4, 7-diphenyl-1,10-phenanthroline), TpPyPB and DPPS may be formed of a material containing at least one selected from the group consisting of. A method of forming the electron transport layer 150c is not particularly limited.

A buffer layer (not shown) for minimizing damage by a transparent electrode layer may be additionally formed on the surface of the electron transport layer, and the buffer layer is zinc oxide (ZnO), tin oxide (SnO ₂ ), aluminum doped zinc oxide (Al: It may be metal oxide nanoparticles such as ZnO), or a thin film, and the method of forming the buffer layer is not particularly limited, such as spin coating, atomic layer deposition, and thermal evaporation.

The transparent electrode layer 150d may use the same material as the lower transparent conductive layer 120 , and it is also possible to use a material different from the lower transparent conductive layer 120 as the above-mentioned transparent conductive material.

On the other hand, although the perovskite absorption region 150 is shown as a single cell in FIG. 1, the present invention is not limited thereto, and the perovskite absorption region may have a structure in which a plurality of cells are connected in series or parallel. do. This will be described later.

An upper metal electrode 160 for collecting current is formed on the upper transparent electrode. The upper metal electrode 160 extends across the region where the encapsulation cap structure 170 is formed so that the electrode can be withdrawn to the outside. The encapsulation cap structure 170 is manufactured in a separate structure shape, is a structure for sealing the perovskite absorption region 150 with a material such as glass or plastic, and includes a cavity therein. The encapsulation cap structure 170 includes at least the encapsulation cap structure 170 that is bonded to the substrate 110 through the adhesive material 180 while sealing the perovskite absorption region 150 . On the other hand, the optical characteristics of the encapsulation cap structure 170 may not cause optical loss of the encapsulated perovskite solar cell because there is almost no light absorption in the visible and infrared regions. When performing the encapsulation process of attaching the encapsulation cap structure 170 to the lower substrate structure using the adhesive material 180, the process may be performed in an inert gas atmosphere such as argon or nitrogen in a closed space such as a glove box. . According to this process, an inert gas may be included in the inner cavity of the encapsulation cap structure 170 .

On the other hand, it is also possible to include an additional anti-reflection film (not shown) on the upper portion of the encapsulation cap structure 170 . In this case, the refractive index of the additional anti-reflection film (not shown) may be a single layer or a double layer composed of a material having a refractive index smaller than that of the sealing glass (about 1.5) and larger than that of air (about 1).

The lower transparent conductive layer 120 intersects the direction in which the upper metal electrode 160 is formed, for example, in order to draw the electrode out in a substantially vertical direction, the lower transparent conductive layer 120 is insulated to have a strip shape It has a structure of the lower transparent electrode 120a separated by the region 130 . As the insulating material filled in the insulating region 130 , a polymer insulating material such as polystyrene, poly(methyl methancrylate), or polydimetylsiloxane having a melting point of 150°C or higher may be used. The insulating region 130 is filled with an insulating material, and the insulating material selectively etches the lower transparent conductive layer 120 to a predetermined line width to form the lower transparent electrode 120a, a UV laser pulse in the etched region. can be used to transfer the insulating material.

In addition, the encapsulation cap structure 170 and the substrate 110 are adhered through the adhesive material 180, and the adhesive material 180 is prevented from permeating into the cavity region (the empty space between the upper metal electrode and the encapsulation cap structure). To this end, a groove 190 through which an adhesive material can flow is provided in a portion where the encapsulation cap structure 170 contacts the upper metal electrode line, the lower transparent electrode 120, and the like. The groove 190 is formed in a band shape having a predetermined width in the entire region where the encapsulation cap structure 170 contacts the substrate 110 (see FIG. 1 ).

When the upper electrode is extended, a part of the perovskite solar cell is exposed to the outside of the encapsulation cap structure 170, and the deterioration of the perovskite solar cell occurs in the exposed area. A phenomenon in which the efficiency decreases rapidly was observed. When the perovskite absorption layer exposed to the outside of the encapsulation cap structure is removed to prevent such a problem, the upper and lower electrodes come into direct contact with each other, resulting in a short circuit problem.

Therefore, it was recognized that the lower transparent conductive layer was etched to prevent the deterioration of the perovskite outside the encapsulation cap structure and the direct contact of the upper/lower electrodes. The lower transparent electrode can be etched to have a line width of several tens of μm using a chemical method or a laser scribing method. / It was confirmed that direct contact of the lower electrode can be prevented. In this case, the inventors confirmed that the distance (d in FIG. 1) between the ends of the insulating region 130 and the perovskite absorption region 150 is an important factor. If the length of d in FIG. 1 is 2000 to 5000 μm or more, deterioration of the perovskite may occur due to contact with the adhesive material. There are problems with which this can happen. Accordingly, the distance between the insulating region 130 and the end of the perovskite absorption region 150 is preferably in the range of 1000 to 2000 μm.

Even if the perovskite absorption region is formed outside the etch line (insulation region), complete insulation may not be achieved by the conductive hole transport layer or the perovskite absorption layer, and also the surface of the hole transport layer or the perovskite solution If the formation of the film is incomplete due to the wetting characteristics according to the tension and rheological characteristics, a short circuit may occur due to direct contact between the upper and lower electrodes.

In order to solve this problem, a short circuit in the etched region may be further prevented by transferring the insulating material to the etched region of the lower transparent electrode using a laser transfer method.

Referring to FIG. 3 , first, a transparent conductive layer 220 is formed on a substrate 210 . Thereafter, the transparent conductive layer 220 is selectively etched using a laser. Then, a process of transferring the insulating material using a laser is performed. The laser transfer process uses a transfer substrate in which a laser absorption layer 320 and an insulating material 330 are formed on a transparent substrate 310 . And, by using the same laser alignment coordinates as the etching, it may be implemented so that a laser alignment step for an additional transfer process is not required.

Since the insulating material should not be decomposed or peeled off by heat generated during the laser transfer process, the applicable insulating material may be a polymer insulating material such as polystyrene, poly(methyl methancrylate), or polydimetylsiloxane having a melting point of 150 degrees or more.

On the other hand, a laser energy absorbing layer (320) for absorbing the energy of the laser and reducing the laser energy to transfer the insulating material without damage may be additionally provided, which is titanium (titanium), triazene polymer (triazene) polymers), indium tin oxide, or polyimide.

1, the solar cell of FIG. 4 is a case in which the perovskite absorption region 150 of FIG. 1 has a tandem structure composed of a lower cell CIGS cell and an upper cell perovskite cell. Accordingly, a description of the overlapping region with FIG. 1 will be omitted.

The present solar cell includes a lower transparent conductive layer 320 stacked on a substrate 310 and has perovskite absorption regions 350 (350a to 350i) on the lower transparent conductive layer 320 .

The upper cell, the perovskite cell, may be a structure in which a thin film is formed in the order of a hole transport layer 350a, a metal halide perovskite 350b, an electron transport layer 350c, a buffer layer 350d, and a transparent electrode 350e. .

The lower cell CIGS cell includes a CIGS absorption layer 350f, a buffer layer 350g, a transparent window 350h, and a recombination layer 350i on the lower transparent electrode layer 320 .

The buffer layer 350g may include cadmium sulfide, zinc sulfide, indium oxide, or the like, and may alleviate a difference in interlayer bandgap energy and a lattice constant between the CIGS absorption layer 350f and the transparent window layer 350h.

The transparent window layer 350h may include a metal oxide doped with p-type or n-type impurities. The metal oxide may include at least one material selected from zinc oxide, gallium oxide, aluminum oxide, indium oxide, lead oxide, copper oxide, titanium oxide, tin oxide, iron oxide, and indium tin oxide.

The recombination layer 350i may include a transparent conductive oxide having high long-wavelength transmittance in order to minimize electrical and optical loss between the upper and lower cells. At least one oxide of indium, tin, and zinc, for example, indium tin oxide, indium zinc oxide, zinc tin oxide, or aluminum zinc oxide, including aluminum, boron, hydrogen, zirconium zinc oxide, zinc boron oxide, indium hydride It may include at least one material selected from oxide or zirconium tin oxide.

In the solar cell of FIG. 4 , the recombination layer 350i of the tandem has a smaller area than the upper hole transport layer 350a in order to prevent a short circuit due to contact with the extended upper electrode 360. It is preferable to form

Referring to the difference from FIG. 1, the solar cell of FIG. 5 is a case in which the perovskite absorption region 150 of FIG. 1 is connected to a plurality of cells. A description of the overlapping region with FIG. 1 will be omitted.

The solar cell of FIG. 5 includes a lower transparent conductive layer 420 stacked on a substrate 410, and a perovskite absorption region 450; 450a, b, c, d) on the lower transparent conductive layer 420. to provide The perovskite absorption region 450 means a stacked structure including a perovskite absorption layer, and in FIG. 5 , it consists of cells of three regions.

For example, in FIG. 5 , the hole transport layer 450a, the metal halide perovskite 450b, the electron transport layer 450c, and the buffer layer 450d are formed in this order, and the upper electrode 460 is additionally The formed structure is shown.

In FIG. 5 , the lower transparent conductive layer 420 is formed with the first isolation region P1 . The isolation region P1 is cut by a laser process after the lower transparent conductive layer 420 is formed. Then, by forming the hole transport layer 450a in the entire region where the first isolation region P1 is formed, the hole transport layer 450a is also filled in the isolation region P1. In the first isolation region P1, the lower transparent conductive layer 420 was etched to prevent a short circuit due to direct contact between the upper and lower electrodes.

In addition, after the hole transport layer 450a, the metal halide perovskite 450b, the electron transport layer 450c, and the buffer layer 450d are formed, a second isolation region P2 is formed as shown in FIG. 5 . Thereafter, an upper transparent electrode 460 is additionally formed over the entire region including the second isolation region, and a third isolation region P3 is formed to form a unit cell.

According to the structure of FIG. 5 , in the three unit cells, the lower transparent conductive layer 420 is implemented to be separated by the isolation regions P1 and the insulating region 430 , respectively.

In the structure of FIG. 5 , the lead-out terminal of the lower electrode is an external exposed region of the lower transparent conductive layer 420 , and the upper electrode contact region is a region where the upper transparent electrode 460 extends to the outside.

As mentioned above, although the embodiments of the present specification have been described with reference to the accompanying drawings, those of ordinary skill in the art to which this specification belongs can realize that the present invention may be embodied in other specific forms without changing the technical spirit or essential features thereof. you will be able to understand Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.

Claims

A solar cell comprising perovskite,

Board;

a lower transparent conductive layer, a perovskite absorption region, and an upper metal electrode sequentially formed on the substrate; and

and an encapsulation cap structure that is adhered to the substrate through an adhesive material while encapsulating at least the perovskite absorption region;

The upper electrode extends past the end of the encapsulation cap structure in the first direction, and the electrode is withdrawn to the outside;

The lower transparent conductive layer includes perovskite having a structure in which the lower transparent conductive layer is separated by an insulating region so as to have a strip shape in order to withdraw the electrode to the outside in a second direction intersecting the first direction battery.
According to claim 1,

The encapsulation cap structure and the substrate are bonded through an adhesive material,

A solar cell comprising a perovskite, characterized in that a groove through which an adhesive material can flow is installed in a portion of the encapsulation cap structure in contact with the substrate in order to prevent the adhesive material from permeating into the cavity region.
According to claim 1,

The perovskite absorption region is a solar cell comprising perovskite, characterized in that the single cell or tandem cell including the perovskite absorption layer.
According to claim 1,

The perovskite absorption region has a structure connected to a plurality of cells, and in this case, a solar cell comprising perovskite, characterized in that the lower transparent conductive layer has an additional insulating region in addition to the isolation region.
According to claim 1,

When the perovskite absorption region is a tandem cell, the recombination layer for bonding the upper cell and the lower cell is formed in a smaller area than the stacked upper layer.
According to claim 1,

The insulating region is filled with an insulating material, and the insulating material is a perovskite formed by selectively etching the lower transparent conductive layer to a predetermined line width, and transferring the insulating material to the etched region using a laser transfer method. including solar cells.
7. The method of claim 6,

The insulating material is a solar cell including a perovskite, characterized in that the polymer insulating material such as polystyrene, poly(methyl methancrylate), or polydimetylsiloxane having a melting point of 150 degrees or more.
According to claim 1,

A solar cell comprising perovskite, characterized in that the distance between the insulating region and the end of the perovskite absorption region is in the range of 1000 to 2000 μm.