Tandem solar cell and method for manufacturing same

Abstract

The present invention relates to a method for manufacturing a solar cell comprising the steps of: preparing a perovskite solar cell including a first conductive charge transfer layer, a light absorbing layer, and a second conductive charge transfer layer on a substrate; forming a separation portion in the perovskite solar cell to form a first perovskite unit solar cell and a second perovskite unit solar cell; forming a contact portion in the first perovskite unit solar cell to expose a predetermined region of the first perovskite unit solar cell; the buffer layer; preparing a plurality of second solar cells; bonding the plurality of second solar cells onto the buffer layer to form a first unit tandem solar cell in which the first perovskite unit solar cell, the buffer layer, and the second solar cell are stacked in that order; and a second unit tandem solar cell in which the second perovskite unit solar cell, the buffer layer, and the second solar cell are stacked in that order; and electrically connecting the first unit tandem solar cell and the second unit tandem solar cell.

Description

[Technical field]

[0001] The present invention relates to tandem solar cells, and more particularly to tandem solar cells including perovskite solar cells. [Background technology]

[0002] A tandem solar cell is a solar cell that improves cell efficiency by stacking two solar cells one on top of the other.

[0003] Previously, there have been attempts to apply solar cells using perovskite compounds to tandem solar cells, and one idea has been proposed to manufacture a tandem solar cell by manufacturing a substrate-type solar cell and stacking a solar cell using a perovskite compound on the substrate-type solar cell by a deposition process or a coating process.

[0004] However, such a conventional method for manufacturing a tandem solar cell has problems in that the manufacturing process is complicated and it is difficult to achieve current matching between the substrate type solar cell and the solar cell using a perovskite compound. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been devised to solve the above-mentioned problems in the conventional technology, and an object of the present invention is to provide a tandem solar cell that has a simple manufacturing process and facilitates current matching between a substrate-type solar cell and a solar cell using a perovskite compound, and a manufacturing method thereof. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention provides a method for manufacturing a perovskite solar cell, comprising the steps of: preparing a perovskite solar cell including a first conductive charge transfer layer, a light absorbing layer, and a second conductive charge transfer layer on a substrate; forming a separation portion in the perovskite solar cell to form a first perovskite unit solar cell and a second perovskite unit solar cell; forming a contact portion in the first perovskite unit solar cell to expose a predetermined region of the first perovskite unit solar cell; the first perovskite unit solar cell, the buffer layer, and the second solar cell stacked in order to form a first unit tandem solar cell, and the second perovskite unit solar cell, the buffer layer, and the second solar cell stacked in order to form a second unit tandem solar cell, and the second perovskite unit solar cell, the buffer layer, and the second solar cell stacked in order to form a first unit tandem solar cell, and the second unit tandem solar cell, and the first unit tandem solar cell and the second unit tandem solar cell stacked in order to form a second unit tandem solar cell.

[0007] Preparing the perovskite solar cell may include sequentially forming the first conductive charge transfer layer, the light absorbing layer, and the second conductive charge transfer layer on the substrate.

[0008] Forming the isolation portion can include removing predetermined regions of the first conductive charge transfer layer, the light absorbing layer, and the second conductive charge transfer layer to expose the top surface of the substrate.

[0009] Forming the contact portion may include removing predetermined regions of the light absorbing layer and the second conductive charge transfer layer to expose an upper surface of the first conductive charge transfer layer.

[0010] The step of forming the buffer layer may include the steps of forming a film having a plurality of holes on an upper surface of each of the first perovskite unit solar cell and the second perovskite unit solar cell, and filling the insides of the plurality of holes in the film with a conductive layer.

[0011] The step of forming the film having the plurality of holes may include forming the film in a semi-dry state, and the step of forming the first unit tandem solar cell and the second unit tandem solar cell may include disposing the second solar cell on the buffer layer and then curing the film in the semi-dry state.

[0012] The plurality of holes provided in the film may include a plurality of first holes extending through the film in a first direction, and a plurality of second holes extending through the film in a second direction intersecting the first direction, and the conductive layer may be in contact with upper surfaces of the first and second perovskite unit solar cells and a lower surface of the second solar cell.

[0013] The film does not overlap the contact portion, and the contact portion can be exposed without being covered by the film.

[0014] The process of electrically connecting the first unit tandem solar cell and the second unit tandem solar cell may include electrically connecting an electrode pattern provided on an upper surface of the second solar cell of the second unit tandem solar cell and the first conductive charge transfer layer of the first perovskite unit solar cell exposed at the contact portion of the first unit tandem solar cell via a connection line.

[0015] The connection line may extend along a side surface of the second solar cell of the second unit tandem solar cell and a side surface of the buffer layer thereunder, cross the separator, extend along an upper surface and a side surface of the second conductive charge transfer layer of the first perovskite unit solar cell provided on one side of the contact portion and a side surface of the light absorbing layer, and extend to an upper surface of the first conductive charge transfer layer of the first perovskite unit solar cell exposed to the contact portion.

[0016] The step of preparing the plurality of second solar cells may include a step of forming an electrode pattern having the same pattern as the conductive layer, and the step of bonding the plurality of second solar cells may include a step of overlapping the conductive layer and the electrode pattern.

[0017] The present invention also provides a tandem solar cell including: a first unit tandem solar cell formed on a substrate and stacked in that order on a first perovskite unit solar cell, a buffer layer, and a second solar cell; a second unit tandem solar cell formed on the substrate and separated from the first unit tandem solar cell by a separator and stacked in that order on a second perovskite unit solar cell, a buffer layer, and a second solar cell; and a connection line connecting the first unit tandem solar cell and the second unit tandem solar cell.

[0018] The first perovskite unit solar cell may include a first conductive charge transfer layer provided on the substrate, a light absorbing layer formed on the first conductive charge transfer layer, a second conductive charge transfer layer formed on the light absorbing layer, and a contact portion removing predetermined regions of the light absorbing layer and the second conductive charge transfer layer to expose an upper surface of the first conductive charge transfer layer, and an electrode pattern may be provided on an upper surface of the second solar cell, and the connection line may connect between the electrode pattern provided on an upper surface of the second solar cell of the second unit tandem solar cell and the first conductive charge transfer layer exposed in the contact portion of the first perovskite unit solar cell.

[0019] The contact portion may not overlap the buffer layer.

[0020] The connection line may extend along a side surface of the second solar cell of the second unit tandem solar cell and a side surface of the buffer layer thereunder, cross the separator, extend along an upper surface and a side surface of the second conductive charge transfer layer of the first perovskite unit solar cell provided on one side of the contact portion and a side surface of the light absorbing layer, and extend to an upper surface of the first conductive charge transfer layer of the first perovskite unit solar cell exposed to the contact portion.

[0021] The buffer layer may comprise a film having a plurality of holes, including a plurality of first holes extending in a first direction and a plurality of second holes extending in a second direction intersecting the first direction, and a conductive layer filled inside the plurality of holes, and the conductive layer may be in contact with upper surfaces of the first and second perovskite unit solar cells and a lower surface of the second solar cell.

[0022] An electrode pattern having the same pattern as the conductive layer is provided on an upper surface of the second solar cell, and the electrode pattern can overlap the conductive layer. Effect of the Invention

[0023] According to the present invention as described above, the following effects are obtained.

[0024] According to one embodiment of the present invention, a tandem solar cell is manufactured by forming a buffer layer on a plurality of perovskite unit solar cells and stacking a separately prepared second solar cell on the buffer layer, which simplifies the manufacturing process and facilitates current matching between the perovskite unit solar cells and the second solar cell. [Brief description of the drawings]

[0025] [Figure 1A] FIG. 1A is a cross-sectional view showing steps of a method for manufacturing a tandem solar cell according to an embodiment of the present invention. [Figure 1B] FIG. 1B is a cross-sectional view showing steps of a method for manufacturing a tandem solar cell according to an embodiment of the present invention. [Figure 1C] FIG. 1C is a cross-sectional view showing a process of a method for manufacturing a tandem solar cell according to an embodiment of the present invention. [Figure 1D] FIG. 1D is a cross-sectional view showing steps of a method for manufacturing a tandem solar cell according to an embodiment of the present invention. [Figure 1E] FIG. 1E is a cross-sectional view showing steps of a method for manufacturing a tandem solar cell according to an embodiment of the present invention. [Figure 1F] FIG. 1F is a cross-sectional view showing steps of a method for manufacturing a tandem solar cell according to an embodiment of the present invention. [Figure 1G] FIG. 1G is a cross-sectional view showing steps of a method for manufacturing a tandem solar cell according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic plan view of a buffer layer according to one embodiment of the present invention. [Diagram 3] 4 is a schematic cross-sectional view of a second solar cell according to an embodiment of the present invention. [Figure 4] 6 is a schematic cross-sectional view of a second solar cell according to another embodiment of the present invention. [Diagram 5] 1 is a plan view of a tandem solar cell according to an embodiment of the present invention; [Figure 6] FIG. 4 is a schematic plan view of a second solar cell according to an embodiment of the present invention. [Figure 7] 1 is a schematic cross-sectional view of a tandem solar cell according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The advantages and features of the present invention, as well as the methods for achieving them, will become apparent from the following detailed description of the embodiments in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and may be embodied in various different forms. The embodiments are provided solely to complete the disclosure of the present invention, and to fully convey the scope of the invention to those skilled in the art to which the present invention pertains. The present invention is defined only by the claims.

[0027] The shapes, sizes, ratios, angles, numbers, etc. disclosed in the drawings for explaining the embodiments of the present invention are illustrative, and the present invention is not limited to the matters shown in the drawings. The same reference numerals refer to the same components throughout the specification. In addition, in the description of the present invention, if a specific description of related known technology is deemed to unnecessarily obscure the gist of the present invention, the detailed description will be omitted. When "including," "having," "consisting of," etc. are used in the present invention, other parts may be added unless "only" is used. When a component is expressed in the singular, it includes the case where it includes a plural, unless otherwise expressly stated.

[0028] When interpreting elements, they are interpreted as including a margin of error unless otherwise expressly stated.

[0029] When describing a positional relationship, for example when the positional relationship of two parts is described using "above", "at the top", "below", "beside", etc., one or more other parts may be located between the two parts, unless "immediately" or "directly" is used.

[0030] When describing a temporal relationship, for example, when the temporal precedence / subsequence relationship is described using "after," "following," "next to," "before," etc., non-consecutive cases can also be included, unless "immediately" or "directly" is used.

[0031] Although the terms "first", "second" and the like are used to describe various components, these components are not limited by these terms. These terms are merely used to distinguish one component from another. Therefore, the first component referred to below may also be the second component within the technical spirit of the present invention.

[0032] The features of the various embodiments of the present invention may be partially or fully combined or combined with each other, and may be technically linked and driven in various ways, and each embodiment may be implemented independently of the others, or may be implemented together in a linked relationship.

[0033] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0034] 1A to 1G are cross-sectional views illustrating process steps of a method for manufacturing a tandem solar cell according to one embodiment of the present invention.

[0035] First, as can be seen from FIG. 1A, a perovskite solar cell layer 200 is formed on a substrate 100.

[0036] The substrate 100 may be made of a semiconductor material, such as a silicon wafer, or may be made of glass or plastic.

[0037] The perovskite solar cell layer 200 may be formed by forming a first conductive charge transfer layer 210 on the substrate 100, forming a light absorbing layer 220 on the first conductive charge transfer layer 210, and forming a second conductive charge transfer layer 230 on the light absorbing layer 220.

[0038] When the first conductive charge transport layer 210 is an electron transport layer, the second conductive charge transport layer 230 is a hole transport layer, and when the first conductive charge transport layer 210 is a hole transport layer, the second conductive charge transport layer 230 is an electron transport layer.

[0039] The electron transport layer may include various N-type organic materials known in the art, such as BCP (Bathocuproine), C60, or PCBM (Phenyl-C61-butyric acid methyl ester), various N-type metal oxides known in the art, such as ZnO, c-TiO2 / mp-TiO2, SnO2, or IZO, and various other N-type organic or inorganic materials known in the art.

[0040] The hole transport layer may include various P-type organic materials known in the art, such as Spiro-MeO-TAD, Spiro-TTB, polyaniline, polypinol, poly-3,4-ethylenedioxythiophene-polystyrenesulfonate (PEDOT-PSS), poly-[bis(4-phenyl)(2,4,6-trimethylphenyl)amine] (PTAA), Poly(3-hexylthiophene-2,5-diyl) (P3HT), etc., various P-type metal oxides known in the art, such as Ni oxide, Mo oxide, V oxide, W oxide, Cu oxide, etc., and other P-type organic or inorganic materials known in the art.

[0041] The light absorbing layer 220 is made of a perovskite compound.

[0042] Next, as can be seen from FIG. 1B, a separation portion (P) is formed in the perovskite solar cell layer 200 to form a plurality of perovskite unit solar cells (UC1, UC2, UC3).

[0043] The separation portion (P) is formed by removing predetermined regions of the first conductive charge transfer layer 210, the light absorbing layer 220, and the second conductive charge transfer layer 230 constituting the perovskite solar cell layer 200. The separation portion (P) may be formed through a primary scribing process, particularly a laser scribing process. In the region where the separation portion (P) is formed, the upper surface of the substrate 100 is exposed.

[0044] The first to third perovskite unit solar cells (UC1, UC2, UC3) are obtained in a state separated from one another by the separating portion (P). Here, each of the first to third perovskite unit solar cells (UC1, UC2, UC3) includes the first conductive charge transfer layer 210, the light absorbing layer 220, and the second conductive charge transfer layer 230.

[0045] The separating portion (P) may be formed to have a first width (W1).

[0046] Next, as shown in FIG. 1C, a contact portion (C) is formed in each of the first and second perovskite unit solar cells (UC1, UC2). The contact portion (C) is separated from the separation portion (P). The contact portion (C) is formed by removing predetermined regions of the light absorbing layer 220 and the second conductive charge transfer layer 230.

[0047] The contact portion (C) is for connecting the first to third perovskite unit solar cells (UC1, UC2, UC3) in series. The contact portion (C) may be formed through a secondary scribing process, particularly a laser scribing process. In the region where the contact portion (C) is formed, the upper surface of the first conductive charge transfer layer 210 is exposed. The formation of the contact portion (C) may be omitted for the third unit solar cell (UC3) located at one end, for example, the right end, of the plurality of perovskite unit solar cells (UC1, UC2, UC3).

[0048] The contact portion (C) may be formed to have a second width (W2). Here, by forming the second width (W2) of the contact portion (C) to be larger than the first width (W1) of the separation portion (P), the process of FIG. 1G described later can be easily performed.

[0049] Next, as can be seen from FIG. 1D, a film 310 having a plurality of holes (H) is formed on the upper surface of each of the first to third perovskite unit solar cells (UC1, UC2, UC3).

[0050] That is, one film 310 having a plurality of holes (H) is formed on the upper surface of a first perovskite unit solar cell (UC1), a different film 310 having a plurality of holes (H) is formed on the upper surface of a second perovskite unit solar cell (UC2), and another different film 310 having a plurality of holes (H) is formed on the upper surface of a third perovskite unit solar cell (UC3). Here, the one film 310 formed on the upper surface of the first perovskite unit solar cell (UC1), the different film 310 formed on the upper surface of the second perovskite unit solar cell (UC2), and the different film 310 formed on the upper surface of the third perovskite unit solar cell (UC3) are spaced apart without being in contact with each other.

[0051] The film 310 may be made of an organic polymer compound, but is not necessarily limited thereto. Here, the film 310 made of the organic polymer compound may be formed in a semi-dry state. The semi-dry state refers to a state before being completely cured, and refers to a state in which it can be bonded to other components without a separate adhesive layer through a subsequent curing process.

[0052] The plurality of holes (H) are formed to penetrate the film 310, thereby exposing an upper surface of the second conductive charge transfer layer 230 of each of the first to third perovskite unit solar cells (UC1, UC2, UC3) through the plurality of holes (H).

[0053] The film 310 is formed so as not to overlap the contact portion (C), so that the contact portion (C) is exposed without being blocked by the film 310, thereby facilitating the process of FIG. 1G described below.

[0054] Meanwhile, the film 310 may be formed so as not to overlap with the separation portion (P), but this is not necessarily limited thereto, and it may also be formed so as to overlap with the separation portion (P), in which case the connecting line 500 can be shortened in the process of FIG. 1G described later.

[0055] 1E, the insides of the holes (H) of the film 310 provided on the upper surface of each of the first to third perovskite unit solar cells (UC1, UC2, UC3) are filled with a conductive layer 320. As a result, the buffer layer 300 consisting of the film 310 and the conductive layer 320 is formed on the upper surface of each of the first to third perovskite unit solar cells (UC1, UC2, UC3).

[0056] The conductive layer 320 may be made of, but is not limited to, a metal material, and may be filled into the holes (H) of the film 310 through a printing process, but is not limited to this.

[0057] The conductive layer 320 contacts the upper surface of the second conductive charge transfer layer 230 at the bottom of the holes (H).

[0058] Even with the conductive layer 320 formed, the film 310 can maintain a semi-dry state.

[0059] The buffer layer 300 will be described below with reference to FIG.

[0060] FIG. 2 is a schematic plan view of the buffer layer 300 according to one embodiment of the present invention. As can be seen from FIG. 2, the buffer layer 300 according to one embodiment of the present invention may include a film 310 having a plurality of holes (H1, H2), and a conductive layer 320 filled in the plurality of holes (H1, H2).

[0061] The plurality of holes (H1, H2) includes a plurality of first holes (H1) arranged in a first direction, e.g., a horizontal direction, and a plurality of second holes (H2) arranged in a second direction, e.g., a vertical direction. The plurality of first holes (H1) and the plurality of second holes (H2) are formed to intersect with each other, thereby forming a hole (H1, H2) pattern having a lattice structure as a whole.

[0062] The conductive layer 320 is provided to fill the entire interior of the holes H1 and H2, so that the conductive layer 320 may be formed in a lattice structure pattern as a whole.

[0063] 1F, the second solar cell 400 is placed on the buffer layer 300, and then the film 310 constituting the buffer layer 300 is cured through a curing process to bond the film 310 to the second solar cell 400. In this way, a plurality of unit tandem solar cells (UTC1, UTC2, UTC3) are formed.

[0064] That is, a first unit tandem solar cell (UTC1) in which a first perovskite unit solar cell (UC1), a buffer layer 300, and a second solar cell 400 are stacked in sequence, a second unit tandem solar cell (UTC2) in which a second perovskite unit solar cell (UC2), a buffer layer 300, and a second solar cell 400 are stacked in sequence, and a third unit tandem solar cell (UTC3) in which a third perovskite unit solar cell (UC3), a buffer layer 300, and a second solar cell 400 are stacked in sequence are formed spaced apart from each other.

[0065] Here, the second solar cell 400 is attached to the buffer layer 300 while being fabricated as an individual solar cell.

[0066] The second solar cells 400 are individually formed on the upper surface of each of the first to third perovskite unit solar cells (UC1, UC2, UC3), and the individually formed second solar cells 400 are spaced apart from each other.

[0067] As a result, first to third perovskite unit solar cells (UC1, UC2, UC3) are formed below the buffer layer 300, and the second solar cell 400 is formed above them.

[0068] Here, the first to third perovskite unit solar cells (UC1, UC2, UC3) and the second solar cell 400 may be electrically connected to each other by a conductive layer 320 in the buffer layer 300. The conductive layer 320 contacts an upper surface of the second conductive charge transfer layer 230 of the first to third perovskite unit solar cells (UC1, UC2, UC3) and a lower surface of the second solar cell 400, respectively.

[0069] The second solar cell 400 may be a substrate type solar cell, which will be described below with reference to FIGS.

[0070] FIG. 3 is a schematic cross-sectional view of a second solar cell 400 according to an embodiment of the present invention.

[0071] As can be seen from FIG. 3, the second solar cell 400 according to an embodiment of the present invention includes a semiconductor substrate 410 , a first semiconductor layer 420 , a second semiconductor layer 430 , and an electrode pattern 470 .

[0072] The semiconductor substrate 410 may be an N-type or P-type semiconductor wafer. Although not specifically shown in the drawings, at least one of the upper and lower surfaces of the semiconductor substrate 410 may have a concave-convex structure, and in this case, the first semiconductor layer 420 and the second semiconductor layer 430 may also have a concave-convex structure corresponding to the concave-convex structure of the semiconductor substrate 410.

[0073] The first semiconductor layer 420 is formed on the upper surface of the semiconductor substrate 410 and is formed to have a predetermined polarity, and the second semiconductor layer 430 is formed on the lower surface of the semiconductor substrate 410 and is formed to have a polarity different from that of the first semiconductor layer 420.

[0074] In particular, the second semiconductor layer 430 constituting the lower surface of the second solar cell 400 is in contact with the conductive layer 320 in the buffer layer 300 and is formed to have a polarity different from that of the second conductive charge transfer layer 230. For example, when the second conductive charge transfer layer 230 is an electron transfer layer, the second semiconductor layer 430 may be formed to have a P-type polarity and the first semiconductor layer 420 may be formed to have an N-type polarity, and when the second conductive charge transfer layer 230 is a hole transfer layer, the second semiconductor layer 430 may be formed to have an N-type polarity and the first semiconductor layer 420 may be formed to have a P-type polarity.

[0075] The first semiconductor layer 420 and the second semiconductor layer 430 may be formed by doping a predetermined dopant into the upper and lower surfaces of the semiconductor substrate 410, respectively. In this case, the first semiconductor layer 420 and the second semiconductor layer 430 may be made of a semiconductor wafer, similar to the semiconductor substrate 410.

[0076] The electrode pattern 470 is patterned on the upper surface of the first semiconductor layer 420. The electrode pattern 470 may be formed through a process known in the art, such as screen printing.

[0077] FIG. 4 is a schematic cross-sectional view of a second solar cell 400 according to another embodiment of the invention.

[0078] As can be seen from FIG. 4, a second solar cell 400 according to another embodiment of the present invention includes a semiconductor substrate 410 , a first semiconductor layer 420 , a second semiconductor layer 430 , a third semiconductor layer 440 , a fourth semiconductor layer 450 , and an electrode pattern 470 .

[0079] The semiconductor substrate 410 may be an N-type or P-type semiconductor wafer. Although not specifically shown in the drawings, at least one of the upper and lower surfaces of the semiconductor substrate 410 may have an uneven structure. In this case, the first to fourth semiconductor layers 420, 430, 440, and 450 may also have an uneven structure corresponding to the uneven structure of the semiconductor substrate 410.

[0080] The first semiconductor layer 420 may be formed on the upper surface of the semiconductor substrate 410 through a thin film deposition process such as chemical vapor deposition (CVD) or atomic layer deposition (ALD), and may be an intrinsic semiconductor layer, although in some cases, the first semiconductor layer 420 may be a semiconductor layer doped with a small amount of dopant.

[0081] The second semiconductor layer 430 is formed on the upper surface of the first semiconductor layer 420. The second semiconductor layer 430 may be formed through a thin film deposition process and may be a semiconductor layer doped with a large amount of dopant. The first semiconductor layer 420 may be formed by doping a small amount of dopant having the same polarity as the semiconductor substrate 410, and then the second semiconductor layer 430 may be formed by doping the dopant with a large amount.

[0082] The third semiconductor layer 440 is formed on the lower surface of the semiconductor substrate 410. The third semiconductor layer 440 is formed through a thin film deposition process and may be an intrinsic semiconductor layer. However, in some cases, the third semiconductor layer 440 may be a semiconductor layer doped with a small amount of dopant. Here, the polarity of the dopant doped in the third semiconductor layer 440 is opposite to that of the dopant doped in the first semiconductor layer 420.

[0083] The fourth semiconductor layer 450 is formed on the lower surface of the third semiconductor layer 440. The fourth semiconductor layer 450 may be formed through a thin film deposition process and may be a semiconductor layer doped with a large amount of dopant. Here, the polarity of the dopant doped in the fourth semiconductor layer 450 is opposite to the polarity of the dopant doped in the second semiconductor layer 430. The third semiconductor layer 440 may be formed by doping a small amount of a dopant having a polarity different from that of the semiconductor substrate 410, and then the fourth semiconductor layer 450 may be formed by doping the dopant with a large amount.

[0084] The fourth semiconductor layer 450 constituting the lower surface of the second solar cell 400 is in contact with the conductive layer 320 in the buffer layer 300 and is formed to have a polarity different from that of the second conductive charge transfer layer 230. For example, when the second conductive charge transfer layer 230 is an electron transfer layer, the fourth semiconductor layer 450 may be formed to have a P-type polarity, and when the second conductive charge transfer layer 230 is a hole transfer layer, the fourth semiconductor layer 450 may be formed to have an N-type polarity.

[0085] The electrode pattern 470 is patterned on the upper surface of the second semiconductor layer 430. The electrode pattern 470 may be formed through a process known in the art, such as screen printing.

[0086] Next, as can be seen from FIG. 1G, the plurality of unit tandem solar cells (UTC1, UTC2, UTC3) are electrically connected to each other via connection lines 500.

[0087] Specifically, the first unit tandem solar cell (UTC1) and the second unit tandem solar cell (UTC2) can be connected in series through one connection line 500, and the second unit tandem solar cell (UTC2) and the third unit tandem solar cell (UTC3) can be connected in series through another connection line 500.

[0088] The one connection line 500 electrically connects the first conductive charge transfer layer 210 exposed at the contact portion (C) of the first unit tandem solar cell (UTC1) and the upper surface of the second solar cell 400 of the second unit tandem solar cell (UTC2). Here, the upper surface of the second solar cell 400 of the second unit tandem solar cell (UTC2) connected to the one connection line 500 may be formed with the electrode pattern 470 of FIG. 3 and FIG. 4 described above. Here, the polarity of the first semiconductor layer 420 of FIG. 3 or the second semiconductor layer 430 of FIG. 4 provided under the electrode pattern 470 is opposite to the polarity of the first conductive charge transfer layer 210, so that the first unit tandem solar cell (UTC1) and the second unit tandem solar cell (UTC2) are connected in series.

[0089] The one connection line 500 extends along the upper surface and side of the second solar cell 400 of the second unit tandem solar cell (UTC2) and the side of the buffer layer 300 thereunder, crosses the separation portion (P) between the first unit tandem solar cell (UTC1) and the second unit tandem solar cell (UTC2), extends along the upper surface and side of the second conductive charge transfer layer 230 and the side of the light absorbing layer 220 provided on one side, specifically the right side, of the contact portion (C) of the first unit tandem solar cell (UTC1) without overlapping with the buffer layer 300, and extends to the upper surface of the first conductive charge transfer layer 210 exposed to the contact portion (C) of the first unit tandem solar cell (UTC1). Here, an end of the one connection line 500 does not contact the other side, specifically the light absorbing layer 220 provided on the left side of the contact portion (C) of the first unit tandem solar cell (UTC1).

[0090] FIG 5 is a plan view of a tandem solar cell according to an embodiment of the present invention, which relates to a tandem solar cell manufactured by the manufacturing method according to the above-mentioned FIG 1A to FIG 1G. Therefore, the same reference numerals are given to the same components.

[0091] 5, the tandem solar cell according to an embodiment of the present invention includes a first unit tandem solar cell (UTC1), a second unit tandem solar cell (UTC2), and a third unit tandem solar cell (UTC3). The number and arrangement of the unit tandem solar cells (UTC1, UTC2, UTC3) can be variously changed.

[0092] A separation portion (P) is formed between the first unit tandem solar cell (UTC1) and the second unit tandem solar cell (UTC2), and between the second unit tandem solar cell (UTC2) and the third unit tandem solar cell (UTC3). Thus, the unit tandem solar cells (UTC1, UTC2, UTC3) are separated from each other by the separation portion (P). The separation portion (P) may be formed in a first direction, for example, in a vertical direction.

[0093] Also, each of the first unit tandem solar cell (UTC1) and the second unit tandem solar cell (UTC2) has a contact portion (C). The contact portion (C) of the first unit tandem solar cell (UTC1) is formed in the same first direction as the separation portion (P) near the separation portion (P) between the first unit tandem solar cell (UTC1) and the second unit tandem solar cell (UTC2). Similarly, the contact portion (C) of the second unit tandem solar cell (UTC2) is formed in the same first direction as the separation portion (P) near the separation portion (P) between the second unit tandem solar cell (UTC2) and the third unit tandem solar cell (UTC3).

[0094] Electrode patterns 470a, 470b are formed on the upper surface of each of the first to third unit tandem solar cells (UTC1, UTC2, UTC3). The electrode patterns 470a, 470b may include a plurality of first electrode patterns 470a extending in the first direction, and a second electrode pattern 470b extending in a second direction different from the first direction, for example, in the left-right direction. The second electrode pattern 470b crosses the plurality of first electrode patterns 470a to electrically connect the plurality of first electrode patterns 470a.

[0095] The first unit tandem solar cell (UTC1) and the second unit tandem solar cell (UTC2) are electrically connected via one connection line 500, and the second unit tandem solar cell (UTC2) and the third unit tandem solar cell (UTC3) are electrically connected via another connection line 500. In particular, the first unit tandem solar cell (UTC1) and the second unit tandem solar cell (UTC2) are connected in series via one connection line 500, and the second unit tandem solar cell (UTC2) and the third unit tandem solar cell (UTC3) are connected in series via another connection line 500.

[0096] One of the connection lines 500 extends from the electrode patterns 470a, 470b of the second unit tandem solar cell (UTC2) to the contact portion (C) of the first unit tandem solar cell (UTC1), and the other of the connection lines 500 extends from the electrode patterns 470a, 470b of the third unit tandem solar cell (UTC3) to the contact portion (C) of the second unit tandem solar cell (UTC2).

[0097] Here, the one connection line 500 may overlap with at least one of the plurality of first electrode patterns 470a and the second electrode pattern 470b of the second unit tandem solar cell (UTC2) and be directly connected to the overlapping at least one first electrode pattern 470a and the second electrode pattern 470b, and extend in a second direction that is the same as the extension direction of the second electrode pattern 470b, and the other one connection line 500 may overlap with at least one of the plurality of first electrode patterns 470a and the second electrode pattern 470b of the third unit tandem solar cell (UTC3) and be directly connected to the overlapping at least one first electrode pattern 470a and the second electrode pattern 470b, and extend in a second direction that is the same as the extension direction of the second electrode pattern 470b.

[0098] Also, the one connecting line 500 passes over one end (C1), for example the right end, of the contact portion (C) of the first unit tandem solar cell (UTC1), but does not extend to the other end (C2), for example the left end, of the contact portion (C), and does not contact the other end (C2) of the contact portion (C). Similarly, the other one connecting line 500 passes over one end (C1), for example the right end, of the contact portion (C) of the second unit tandem solar cell (UTC2), but does not extend to the other end (C2), for example the left end, of the contact portion (C), and does not contact the other end (C2) of the contact portion (C).

[0099] FIG. 6 is a schematic plan view of a second solar cell 400 according to an embodiment of the present invention, illustrating a structure of an electrode pattern 470 of the second solar cell 400 according to an embodiment of the present invention.

[0100] As can be seen from FIG. 6, the electrode pattern 470 is provided on the top of the second solar cell 400, and a plurality of electrode patterns 470 are arranged in a first direction, e.g., a horizontal direction, and in a second direction, e.g., a vertical direction, so that the electrode patterns 470 as a whole can be formed as a lattice structure pattern.

[0101] The electrode pattern 470 may be formed in the same manner as the pattern of the conductive layer 320 in Fig. 2. That is, the lattice structure of the electrode pattern 470 may be formed in the same structure as the lattice structure of the conductive layer 320 in Fig. 2, so that the electrode pattern 470 and the conductive layer 320 may be formed to overlap each other during the bonding process of the second solar cell 400, which will be described below with reference to Fig. 7.

[0102] FIG. 7 is a schematic cross-sectional view of a tandem solar cell according to another embodiment of the present invention.

[0103] As can be seen from FIG. 7, a perovskite solar cell layer 200 is formed on a substrate 100, a buffer layer 300 is formed on the perovskite solar cell layer 200, and a second solar cell 400 is formed on the buffer layer 300.

[0104] The perovskite solar cell layer 200 comprises a first conductive charge transfer layer 210, a light absorbing layer 220, and a second conductive charge transfer layer 230, the configurations of which are the same as those described above, so repeated description will be omitted.

[0105] The buffer layer 300 includes a film 310 and a conductive layer 320, the configurations of which are similar to those described above, so repeated description will be omitted.

[0106] An electrode pattern 470 is formed on the upper part of the second solar cell 400, and although not specifically shown in the figure, under the electrode pattern 470, a semiconductor substrate 410, a first semiconductor layer 420, and a second semiconductor layer 430 may be provided as shown in FIG. 3 above, or a semiconductor substrate 410, a first semiconductor layer 420, a second semiconductor layer 430, a third semiconductor layer 440, and a fourth semiconductor layer 450 may be provided as shown in FIG. 4 above.

[0107] Here, the electrode pattern 470 of the second solar cell 400 is formed to overlap the conductive layer 320 of the buffer layer 300. By forming the electrode pattern 470 and the conductive layer 320 to overlap each other in this manner, it is possible to minimize the loss of light intensity of sunlight entering the solar cell.

[0108] Although the embodiments of the present invention have been described in detail above with reference to the accompanying drawings, the present invention is not necessarily limited to these embodiments, and can be modified in various ways without departing from the scope of the technical idea of ​​the present invention. Therefore, the embodiments disclosed in the present invention are for illustration purposes, not for limiting the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by these embodiments. Therefore, it should be understood that the above-described embodiments are illustrative and not limiting in all respects. The scope of protection of the present invention should be interpreted according to the claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention. [Explanation of symbols]

[0109] 100: Substrate 200: Perovskite solar cell layer 210: First conductive charge transfer layer 220: Absorption layer 230: second conductive charge transfer layer 300: Buffer layer 310:Film 320: Conductive layer 400:Second solar cell 410: Semiconductor substrate 420, 430, 440, 450: first, second, third, fourth semiconductor layers 470: Electrode pattern 500: Connecting line

Claims

1. providing a perovskite solar cell comprising a first conductive charge transfer layer, a light absorbing layer, and a second conductive charge transfer layer over a substrate; forming a separation portion in the perovskite solar cell to form a first perovskite unit solar cell and a second perovskite unit solar cell; forming a contact portion on the first perovskite unit solar cell to expose a predetermined region of the first perovskite unit solar cell; forming a buffer layer on an upper surface of each of the first perovskite unit solar cell and the second perovskite unit solar cell; providing a plurality of second solar cells; bonding the plurality of second solar cells onto the buffer layer to form a first unit tandem solar cell in which the first perovskite unit solar cell, the buffer layer, and the second solar cell are stacked in order, and a second unit tandem solar cell in which the second perovskite unit solar cell, the buffer layer, and the second solar cell are stacked in order; and A method for manufacturing a tandem solar cell, comprising: electrically connecting the first unit tandem solar cell and the second unit tandem solar cell, the step of forming the buffer layer includes the steps of forming a film having a plurality of holes on an upper surface of each of the first perovskite unit solar cell and the second perovskite unit solar cell, and filling the insides of the plurality of holes in the film with a conductive layer; the film does not overlap the contact portion, and the contact portion is exposed without being blocked by the film; A method for manufacturing tandem solar cells.

2. 2. The method of claim 1, wherein the step of preparing the perovskite solar cell comprises the steps of forming, in order, the first conductive charge transfer layer, the light absorbing layer, and the second conductive charge transfer layer on the substrate.

3. 2. The method of claim 1, wherein the step of forming the isolation portion comprises removing predetermined regions of the first conductive charge transfer layer, the light absorbing layer, and the second conductive charge transfer layer to expose an upper surface of the substrate.

4. 2. The method of claim 1, wherein the step of forming the contact portion includes removing predetermined regions of the light absorbing layer and the second conductive charge transfer layer to expose an upper surface of the first conductive charge transfer layer.

5. forming the film having a plurality of holes includes forming the film in a semi-dry state; forming the first unit tandem solar cell and the second unit tandem solar cell includes positioning the second solar cell on the buffer layer and then curing the semi-dry film; The semi-dry state refers to a state before being completely cured, and refers to a state in which the film can be adhered to the second solar cell by the curing without a separate adhesive layer. A method for producing the tandem solar cell according to claim 1 .

6. the plurality of holes provided in the film include a plurality of first holes extending through the film in a first direction, and a plurality of second holes extending through the film in a second direction intersecting the first direction, 2. The method for manufacturing a tandem solar cell according to claim 1, wherein the conductive layer contacts upper surfaces of the first and second perovskite unit solar cells and a lower surface of the second solar cell.

7. 2. The method for manufacturing a tandem solar cell according to claim 1, wherein the step of electrically connecting the first unit tandem solar cell and the second unit tandem solar cell comprises electrically connecting an electrode pattern provided on an upper surface of the second solar cell of the second unit tandem solar cell and the first conductive charge transfer layer of the first perovskite unit solar cell exposed at the contact portion of the first unit tandem solar cell through a connection line.

8. 8. The method for manufacturing a tandem solar cell of claim 7, wherein the connecting line extends along a side surface of the second solar cell of the second unit tandem solar cell and a side surface of the buffer layer below the second solar cell, crosses the separator, extends along an upper surface and a side surface of the second conductive charge transfer layer of the first perovskite unit solar cell provided on one side of the contact portion and a side surface of the light absorbing layer, and extends to an upper surface of the first conductive charge transfer layer of the first perovskite unit solar cell exposed to the contact portion.

9. the step of preparing the plurality of second solar cells includes a step of forming an electrode pattern having the same pattern as the conductive layer; The method for manufacturing a tandem solar cell according to claim 1 , wherein the step of bonding the plurality of second solar cells includes a step of overlapping the conductive layer and the electrode pattern.

10. a first unit tandem solar cell in which a first perovskite unit solar cell, a buffer layer, and a second solar cell are sequentially stacked on a substrate; a second unit tandem solar cell provided on the substrate and separated from the first unit tandem solar cell by a separator, the second unit tandem solar cell being formed by sequentially stacking a second perovskite unit solar cell, a buffer layer, and a second solar cell; and A tandem solar cell including a connection line connecting the first unit tandem solar cell and the second unit tandem solar cell, the first perovskite unit solar cell includes a first conductive charge transfer layer provided on the substrate, a light absorbing layer formed on the first conductive charge transfer layer, a second conductive charge transfer layer formed on the light absorbing layer, and a contact portion in which predetermined regions of the light absorbing layer and the second conductive charge transfer layer are removed to expose an upper surface of the first conductive charge transfer layer; an electrode pattern is provided on an upper surface of the second solar cell; the connection line connects the electrode pattern provided on the upper surface of the second solar cell of the second unit tandem solar cell and the first conductive charge transfer layer exposed at the contact portion of the first perovskite unit solar cell; The contact portion does not overlap the buffer layer. Tandem solar cells.

11. 11. The tandem solar cell of claim 10, wherein the connecting line extends along a side surface of the second solar cell of the second unit tandem solar cell and a side surface of the buffer layer below the second solar cell, crosses the separator, extends along an upper surface and a side surface of the second conductive charge transfer layer of the first perovskite unit solar cell provided on one side of the contact portion and a side surface of the light absorbing layer, and extends to an upper surface of the first conductive charge transfer layer of the first perovskite unit solar cell exposed at the contact portion.

12. the buffer layer includes a film having a plurality of holes, the first holes extending in a first direction and a second hole extending in a second direction intersecting the first direction, and a conductive layer filled in the holes; 11. The tandem solar cell of claim 10, wherein the conductive layer contacts top surfaces of the first and second perovskite unit solar cells and a bottom surface of the second solar cell.

13. The second solar cell is provided on its upper surface with the electrode pattern having the same pattern as the conductive layer, The tandem solar cell of claim 12 , wherein the electrode pattern overlaps the conductive layer.

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