Module stack of perovskite-silicon tandem solar cells

Abstract

Solar cell modules and methods of manufacture are described. In one embodiment, a pair of tandem solar cells are bonded together along a contact flange of a first tandem solar cell using a solid conductive bonding material.

Description

[0001] Related Applications

[0002] This application claims the benefit of priority to U.S. Provisional Application No. 63 / 378,585, filed on October 6, 2022, which is incorporated herein by reference. Background Art Technical Field

[0003] Embodiments described herein relate to solar cells, and more particularly to series connections made between overlapping series-connected solar cells.

[0004] Background Information

[0005] Photovoltaic cells, also known as solar cells, are devices that convert radiant light energy into electrical energy. Multiple solar cells can be integrated into a group to form a solar panel or module, where some or all of the solar cells are typically connected in series to produce an added voltage.

[0006] Conventional silicon solar cells are connected and placed in modules in two main ways. In the first implementation, full or half cells are connected to the front of the solar cell by wire bonds or flat busbar tapes, and specifically to screen-printed metal fingers or busbars. The attached busbars are longer than the cell and can make contact with the back of the next cell in a series connection. In another implementation, smaller cells are connected in series by the following process: the top of one cell is placed below the next cell using a conductive adhesive, and so on, which allows the positive terminal of one cell to contact the negative terminal of the next cell, or vice versa, depending on the type of solar cell used. Summary of the invention

[0007] Solar cell modules and methods of manufacture including overlapping tandem solar cells are described. In some embodiments, a contact flange is patterned into the tandem solar cell to relieve stress applied to the top subcell of the tandem solar cell. More specifically, a contact flange can be formed by an upper perovskite subcell in a tandem perovskite-silicon subcell such that when the tandem subcells in series are connected, this can be achieved by bonding the back of the tandem solar cell to the contact flange of the tandem solar cell below. More specifically, the contact flange can be above the lower silicon subcell of the overlapping tandem solar cells so that pressure is not applied directly above the perovskite subcell.

[0008] In some embodiments, a low temperature conductive adhesive material such as a solid adhesive tape can be used to bond overlapping tandem solar cells in series to each other, or to bond a busbar to the top of a tandem solar cell. Such a low temperature conductive adhesive material can mitigate the degradation of the perovskite subcell material associated with thermal exposure. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 are a schematic top view and a circuit diagram of a solar cell module according to an embodiment.

[0010] Figure 2A is an illustration of a silicon-perovskite tandem solar cell stack based on an n-type silicon substrate, according to one embodiment.

[0011] Figure 2B is an illustration of a silicon-perovskite tandem solar cell stack based on a p-type silicon substrate, according to one embodiment.

[0012] Figure 3A is a schematic top view of a pair of overlapping solar cells according to one embodiment.

[0013] Figure 3B is a schematic side view illustration of a pair of overlapping solar cells according to one embodiment.

[0014] Figure 4 is a schematic cross-sectional side view illustration of mechanical damage in a perovskite subcell.

[0015] Figure 5 is a schematic cross-sectional side view illustration of a pair of overlapping solar cells connected along patterned sub-cell flanges according to one embodiment.

[0016] Fig. 6A is a schematic top view illustration of a transconductive front-side patterned silicon subcell according to one embodiment.

[0017] Figure 6B is a schematic top view illustration of a reformed layer having patterned openings over an underlying silicon pattern according to one embodiment.

[0018] Figure 6C is a schematic top view illustration of a perovskite subcell patterned to expose contact flanges of a recombination layer according to one embodiment.

[0019] Fig.6D is a schematic top view illustration of front fingers and busbars deposited over a patterned solar cell according to one embodiment.

[0020] Figure 7 is a schematic cross-sectional side view illustration of a pair of overlapping solar cells connected along patterned sub-cell flanges according to one embodiment.

[0021] Figure 8 is a schematic cross-sectional side view illustration of a pair of overlapping solar cells according to one embodiment.

[0022] Fig. 9 is a schematic top view illustration of a bus bar on a battery according to one embodiment. DETAILED DESCRIPTION

[0023] The embodiment describes a solar cell module and a manufacturing method. In one embodiment, the solar cell module includes a first tandem solar cell, the first tandem solar cell including a first lower silicon subcell and a first upper perovskite subcell, the first upper perovskite subcell being patterned to form a contact flange above the first lower silicon subcell. The back of the second tandem solar cell is then bonded to the contact flange of the first tandem solar cell with a conductive adhesive material. In this way, the force applied by the back of the second tandem solar cell on the top surface of the first tandem solar cell during assembly, handling, etc. can be absorbed by the first lower silicon subcell instead of by the relatively weaker perovskite subcell, which can reduce the potential mechanical damage of the perovskite subcell. In addition, the second or upper tandem solar cell can be positioned so that the overlap with the first or lower tandem solar cell is minimized, so as not to block the solar cell of the first or lower tandem solar cell. Any suitable conductive adhesive material such as solder, conductive adhesive layer such as solid adhesive tape, liquid adhesive material, etc. can be used to transfer stress in this configuration.

[0024] In some embodiments, a conductive adhesive layer, such as a solid adhesive tape, is used to bond the tandem solar cells. In this way, high temperature bonding processes, such as the use of solder, which may degrade the perovskite subcell material, can be avoided. In addition, the solid adhesive tape can avoid reflow and degradation that may occur using liquid adhesive materials. In addition, the contact flange above the first lower silicon subcell can absorb the bonding pressure so that the conductive material (e.g., pins, particles, etc.) within the conductive adhesive layer is not transferred to the underlying perovskite layer, which may be more susceptible to mechanical deformation, thereby causing device degradation.

[0025] In various embodiments, the description is made with reference to the accompanying drawings. However, certain embodiments may be practiced without one or more of these specific details, or in combination with other known methods and configurations. In the following description, many specific details, such as specific configurations, dimensions, and processes, are set forth in order to provide a thorough understanding of the embodiments. In other cases, well-known semiconductor processes and manufacturing techniques are not described in particular detail in order not to unnecessarily obscure the embodiments.

[0026] References throughout this specification to "one embodiment" mean that a particular feature, structure, configuration, or characteristic described in conjunction with that embodiment is included in at least one embodiment. Thus, the phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment. Furthermore, the particular features, structures, configurations, or characteristics may be combined in any suitable manner in one or more embodiments.

[0027] As used herein, the terms "above," "over," "to," "between," "spanning," and "over" may refer to the relative position of one layer with respect to other layers. A layer that is "above," "over," "spanning," or "on" or bonded "to" or "in contact with" another layer may be in direct contact with the other layer or may have one or more intervening layers. A layer that is "between" layers may be in direct contact with the layers or may have one or more intervening layers.

[0028] Reference now Figure 1 , provides a schematic top view illustration of a solar cell module according to an embodiment. As shown, the solar cell module 100 includes a plurality of cells 115 (also referred to as solar cells) coupled in series with an interconnect 131, wherein the front of one cell is connected to the rear of the next cell so that their voltages (V1 ... V n ) are added. Multiple cells 115 can be arranged into one or more subgroups 110 (e.g., strings) coupled in parallel, which can have the effect of reducing the overall module voltage. Other arrangements are also possible, with the second row of cells offset from the center of the first row of cells by half a cell length, the third row of cells offset from the second row of cells by half a cell length, and so on. In the latter case, a whole row of cells would be connected in parallel. This layout is sometimes referred to as a "matrix" array.

[0029] Reference now FIG. 2A to FIG. 2B , Figure 2A is a silicon-perovskite tandem solar cell stack based on an n-type silicon substrate according to an embodiment; Figure 2B A silicon-perovskite tandem solar cell stack based on a p-type silicon substrate according to an embodiment. In the following description, various layers and components for a solar cell stack are described. It should be understood that each layer may include a single layer or multiple layers. In addition, references to the bottom layer or top layer herein are relative and may not reflect the actual orientation in the product.

[0030] exist FIG. 2A to FIG. 2B In the specific embodiment shown, solar cell 115 can absorb light from the top surface of the illustrated stack. Figure 2A, the tandem structure may include an upper perovskite subcell 220B formed over a lower silicon subcell 220A including a doped silicon substrate 330 (e.g., an n-doped substrate), a p-doped silicon layer 351 (e.g., p+ doped), and an optional n-doped silicon layer 350 (e.g., n+ doped). A back contact 310 may also be formed below the p-doped silicon layer 351. The back contact 310 may be formed of a suitable material such as Ag, Cr, Au, Cu, Al, etc. It should be understood that the exemplary silicon subcell 220A and contacts may include a variety of configurations according to all embodiments, including heterojunction (HJT) designs, tunnel oxide passivation contacts (TOPCon), passivated back contact solar cells (PERC), etc.

[0031] The n-doped silicon layer 350 (e.g., n+ doped) and the p+ doped silicon layer 351 can be crystalline, polycrystalline (such as with a TOPCon design), or amorphous (such as with a HJT design). In such an HJT design, an additional intrinsic layer (e.g., intrinsic silicon) can be formed between the doped silicon substrate 330 and the p-doped silicon layer 351 and the n-doped silicon layer 350. For example, the intrinsic layer can be formed by treating the doped silicon substrate 330 with a hydrogen plasma, for example. The intrinsic layer can also be crystalline or amorphous.

[0032] The recombination layer 355 may be located between the sub-cells 220. The recombination layer 355 may be formed of a transparent conductive material such as TCO or, specifically, ITO.

[0033] The perovskite subcell 220B includes an absorber layer 140 and one or more transport layers. In the illustrated embodiment, the perovskite subcell 220B includes a hole transport layer (HTL) 130 above an optional recombination layer 355, an absorber layer 140 above the HTL 130, and an electron transport layer (ETL) 150 above the absorber layer 140.

[0034] The HTL 130 may include one or more layers formed from metal oxides such as nickel oxide (NiOx) or vanadium oxide (V2O5), organic polymers such as poly(triarylamine) (PTAA), small molecules such as 2,2',7,7'-tetrakis[N,N-di(4-methoxyphenyl)amino]-9,9'-spirobifluorene (spiro-MeOTAD), or a "self-assembled monolayer" in which a hole transport moiety is attached to the underlying TCO or HTL layer via an acid binder group such as a phosphoric acid or carboxylic acid. The HTL 130 may additionally be doped to increase conductivity and may include a double layer of a metal oxide (e.g., NiOx) and an organic layer such as PTAA on top.

[0035] The absorption layer 140 according to the embodiment may be formed of a perovskite material. The perovskite material may be characterized by the formula ABX3, wherein A represents a large atomic or molecular cation (e.g., Cs, methylammonium, formamidine, etc.), B represents a positively charged cation (e.g., metal, lead, lead salt, Sn), and X represents a negatively charged anion (e.g., halide, I, Br, Cl). The perovskite material may also include A 1 m A n B n-1 X3 n-1 A mixture of 2D and 3D structures in the family, where A 1 represents a positively charged cation (eg, butylammonium, phenethylammonium, guanidinium, etc.) Alternative materials such as organic materials may also be used as the absorber layer.

[0036] The ETL 150 according to the embodiment may be formed of fullerenes, metal halides, tin oxide, titanium oxide, naphthalene diimide and related derivatives, etc. An additional buffer layer may be included as part of the ETL 150 or located thereon. For example, the buffer layer may physically separate the electrode layer or the top metal pattern from the sub-cell, more specifically from the absorption layer. In one embodiment, the buffer layer is formed of a metal oxide material such as tin oxide, titanium diode or aluminum zinc oxide (AZO) above the fullerene ETL 150. The buffer layer may be used as a blocking layer as well as a charge transport layer. In a specific embodiment, the electrode layer 170 is formed of a transparent conductive material.

[0037] Since the lower silicon subcell 220A may be opaque, the top electrode layer 170 may be formed of a transparent conductive layer such as poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), a transparent conductive oxide (TCO) such as indium tin oxide (ITO), fluorine-doped tin oxide (FTO), indium zinc oxide (IZO), aluminum-doped zinc oxide (AZO), cadmium stannate, etc. A top metal pattern 181 may then be formed over the transparent top electrode layer 170, for example, to facilitate charge transport. In one embodiment, the top metal pattern is formed of a suitable material such as Ag, Cr, Au, Cu, Al, etc. The top metal pattern 181 may be formed in the shape of a plurality of metal finger 180 electrodes and optionally a bus bar connecting the plurality of metal finger electrodes, so as to transport charge without excessively blocking light transmission.

[0038] refer to Figure 2B , the tandem structure may include an upper perovskite subcell 220B formed over a lower silicon subcell 220A including a doped silicon substrate 330 (e.g., p-doped substrate), an n-doped silicon layer 350 (e.g., n+ doped), and an optional p-doped silicon layer 351 (e.g., p+ doped). Thus, Figure 2BThe lower silicon subcell 220A may be based on a p-doped silicon substrate instead of Figure 2A In such embodiments, the p-doped silicon layer 351 may be optional, whereas the n-doped silicon layer 350 is optional.

[0039] In About FIG. 2A to FIG. 2B In each of the previous embodiments described, a specific stack having an np, pn, nip or pin orientation is described and shown. These changes in the order of layer formation can additionally change the material selection of some layers without departing from the principles of the embodiments. Thus, references to ETL or HTL and n-doped layers or p-doped layers can be reversed, depending on the embodiment.

[0040] In one aspect, it has been observed that conventional silicon solar cells are connected to each other by soldering metal busbars (typically flat metal ribbons of 0.5 mm to 2 mm) to the front of the solar cell. Specifically, the busbar ribbons are soldered to screen-printed metal fingers and busbars (e.g., busbars of the top metal pattern). The attached busbars are typically longer than the solar cell and can contact the next solar cell in a series connection. However, it has been observed that perovskite solar cells (and sub-cells) are sensitive to heat (e.g., temperatures above 150°C can cause damage, while soldering is typically performed at >200°C) as well as pin tip pressure, and therefore the soldering process can damage the perovskite-silicon tandem solar cell. In addition, the connection to the solar cell occurs at only a few solder joints, which also reduces the mechanical stability of the solar cell. It has been observed that each solder joint is one of the most common sources of failure in silicon solar cells.

[0041] According to an embodiment, these problems can be overcome or alleviated by using an electrically conductive adhesive (ECA) to fix the busbar to the solar cell and to bond the solar cells in series. Although ECA is both liquid and solid during application, it has been observed that the liquid used in most commercial ECAs may damage the perovskite solar cell or sub-cell and may therefore not be suitable for series production. It has been observed that during the curing of the ECA, which is liquid during application, the polymer binder component of the adhesive tends to "leak" out of the desired area, thereby negatively affecting the optical properties of the battery area next to the busbar. According to several embodiments, solid ECA tapes can be used. These may include polymer matrix adhesives (e.g., acrylic, silicone, butyl rubber, etc.), in which conductive particles (such as particles made of metals such as silver, copper, aluminum, nickel or particles made of carbon) and / or wires or pins (depending on whether only Z or XYZ conductivity is desired) or metal-coated particles are embedded. When laminated under pressure, the particles and / or wires or pins transmit current directly between the two materials between which the tape is placed.

[0042] Reference now FIG. 3A to FIG. 3B, schematic top view and cross-sectional side view illustrations of a pair of overlapping tandem solar cells 115 according to one embodiment are provided. As shown, the back side of the second tandem solar cell 115B (top solar cell) can be bonded to the first tandem solar cell 115A (bottom solar cell) with a conductive adhesive layer (ECA) 190. Specifically, the ECA 190 can be applied as a solid conductive tape rather than as a liquid adhesive. Such a solid tape may not need to be cured at temperatures common to liquid adhesive materials, which may include silver particles that require a curing temperature that is too high for perovskites. The solid ECA 190 tape may also provide improved mechanical properties because the mechanical connection between the cells relies on a polymer adhesive. This is particularly important for modules that may have to withstand vibration or flexing shapes. Still referring to FIG. 3A to FIG. 3B , a bus bar 185 formed on the first tandem solar cell 115A (bottom solar cell) may be optionally bonded. The bus bar 185 may be formed as part of the top metal pattern 181, which may include metal fingers 180 spanning the first tandem solar cell 115A. However, the bus bar and fingers may be omitted at locations where light transmission is preferred.

[0043] exist FIG. 3A to FIG. 3B In the specific embodiment shown, the second tandem solar cell 115B (top solar cell) can be bonded to the first tandem solar cell 115A (bottom solar cell) at multiple locations. For example, referring back to FIG. 2A to FIG. 2B , the back contacts 310 (electrodes) of the top tandem solar cell 115B can be bonded to the metal fingers 180 (or busbars 185) or electrode layer 170 of the lower tandem solar cell 115A with the ECA 190. As described in further detail herein, the top perovskite subcell 220B of the lower tandem solar cell 115A can be patterned to form a contact flange to avoid stress on the absorber layer 140 of the lower tandem solar cell 115A, which helps avoid short circuits and mechanical breakage when a threshold bonding pressure is exceeded or during installation and operation of a final module including the solar cell strings described herein.

[0044] like FIG. 3A to FIG. 3B As shown, by overlapping two single junction cells (e.g., Figure 2AIt can be straightforward to connect the two single junction cells in series using a single-junction cell (e.g., a tandem solar cell). However, it has been observed that connecting tandem cells can be challenging for several reasons. In particular, both liquid and solid ribbon ECAs typically include irregularly shaped metal particles that are >1 μm in size for liquid ECAs and >25 μm in size for solid ribbon ECAs, and the pressure used to laminate the modules together (e.g., laminating the back surface of the second tandem solar cell 115B onto the top surface of the first tandem solar cell) can cause the particles to “punch through” the <1 μm thick perovskite absorber portion of the lower perovskite subcell 220B, effectively creating a short circuit across the perovskite half of the tandem solar cell. As Figure 4 As shown, when the cell or module is placed under mechanical stresses such as experienced during manufacturing or module installation and operation, local adhesion and pressure at the ECA joint between the perovskite front side and silicon back side of two tandem solar cells can lead to mechanical breakage within the mechanically weak top subcell 220B, such as the perovskite subcell 220B.

[0045] According to some embodiments, the front side of the lower solar cell 115A (often referred to as the "front emitter") is patterned so that the conductive particles (from the ECA 190) do not pass through the front perovskite subcell 220B and negatively affect the electrical characteristics of the connection. Such patterning can be done during the doping process (e.g., for the n-doped silicon layer 350 on a P-type wafer for a Silicon Tunnel Oxide Passivated Contact (TOPCon) or Passivated Emitter and Back Contact (PERC) cell, not necessary for a heterojunction cell), by photolithography or shadow masking during deposition, or by laser patterning post-processing. The recombination layer 355 is typically laterally conductive and can therefore also be patterned in a similar manner. In the case of a heterojunction cell with low conductivity front side (n-side in the most common tandem configuration) passivation, the silicon front side does not need to be patterned, but the recombination layer (e.g., TCO) does need to be patterned. This can be done by a shadow mask or by laser patterning.

[0046] According to an embodiment, the perovskite subcell 220 within the tandem subcell may be relatively weak compared to the silicon subcell 220. According to an embodiment, the perovskite subcell, particularly the absorber layer 140, may be patterned during deposition (e.g., with a shadow mask) or by post-deposition laser ablation.

[0047] exist Figures 5 to 9 In the following description of various connected (e.g., overlapping) tandem solar cell arrangements and methods of manufacturing and assembling are described. In particular, the tandem solar cell arrangements described and illustrated are similar to those described with respect to FIG. 2A to FIG. 2B The tandem solar cell arrangement illustrated and described herein is described in detail. Therefore, specific layers or compositions may not be described separately. FIG. 2A to FIG. 2B The specific arrangements illustrated in describe embodiments, but embodiments are not limited thereto and may be employed using tandem solar cells based on other stacks or other materials that do not include silicon. Embodiments may additionally be used with any material system in which the top subcell is mechanically weaker than the bottom subcell, and are therefore also not limited to perovskite top subcells or silicon-perovskite tandem solar cells.

[0048] Reference now Figure 5 , a schematic cross-sectional side view illustration of a pair of overlapping solar cells connected along a patterned subcell flange according to one embodiment is provided. As shown, the solar cell module may include a first tandem solar cell 115A (lower solar cell) including a first lower silicon subcell 220A and a first upper perovskite subcell 220B, the first upper perovskite subcell being patterned to form a contact flange 195 above the first lower silicon subcell 220A. The second (upper) tandem solar cell 115B also includes a second lower silicon subcell 220A and a second upper perovskite subcell 220B. As shown, the back side 221 of the second lower silicon subcell 220A is bonded to the contact flange 195 with a conductive adhesive layer (ECA) 190. As previously described, the ECA 190 may include a conductive material 194 (e.g., pins, particles, etc.) within a polymer matrix 192. The contact flange 195 may intersect the lateral edge 117 of the first tandem solar cell 115A. It should be understood that other conductive adhesive materials including solder, solder paste, etc. may be used in place of the ECA 190 having this contact flange 195 arrangement while still relieving stress on the upper perovskite subcell 220B.

[0049] As shown in the illustrated specific embodiment, the lateral conductive recombination layer 355 is located between the first lower silicon subcell 220A and the first upper perovskite subcell 220B. A first transparent top electrode layer 170 may also be formed and patterned above the lower perovskite subcell 220B. In the illustrated embodiment, the first transparent top electrode layer optionally does not span the contact ridge 195. A first top metal pattern 181 spanning the first transparent top electrode layer 170 and the lateral conductive recombination layer 355 on the contact ridge 195 may then be formed to form a busbar 185 on the contact ridge. Thus, the busbars 185 and metal fingers 180 of the top metal pattern 181 may be formed simultaneously, or separately. As shown, the back side 221 (which may optionally be FIG. 2A to FIG. 2B The back contact 310) can be bonded to the busbar 185 using ECA 190.

[0050] In order to prevent short circuits between solar cells, patterned line openings of various widths can be formed. For example, a first patterned line opening (P1) can be formed through the top surface of the first lower silicon subcell 220A. In the illustrated embodiment, this can pass through the n-doped silicon layer 350. It should be understood that this is exemplary and the doping can be reversed. Such an opening may not be necessary for a heterojunction (HJT) solar cell. The first patterned line opening can be formed in an appropriate silicon subcell 220A to avoid short circuits between the highly doped layers 350. In the illustrated embodiment, a second patterned line opening (P2) is formed through the lateral conductive recombination layer 355, where P2 is directly above P1 and wider than P1. The back metallization layer and back doping layer of the silicon subcell 220A can be similarly patterned to have a back patterned line opening (Px) to prevent current from flowing in the overlapping area. Px can be directly below P1 and, for example, have a similar size. The relative widths of the openings P1 and P2 can also be reversed, provided that one overlaps the other.

[0051] Multiple overlapping tandem solar cells may be integrated into a module that includes a backsheet 210, a transparent encapsulant 212 surrounding the multiple tandem solar cells, and a transparent cover layer 214 such as glass.

[0052] exist FIG. 6A to FIG. 6D Provided for forming Figure 5 The process sequence of the exemplary solar cell 115 is shown in FIG. Fig. 6A In the example, the sequence may start with a silicon subcell wafer 101 that is patterned through the conductive front and back sides. Depending on the type of silicon subcell to be formed, the front side pattern may be through the n-doped silicon layer 350 of the exemplary embodiment. Figure 6B As shown, a reformed layer 355 may be added and patterned with a second patterned line opening (P2) (eg, a silicon cut) wider than P1. Figure 6C The perovskite subcell 220A is shown formed and patterned to expose the contact flange 195. For example, the contact flange 195 can be the exposed recombined layer 355. The processing of the top perovskite subcell 220B including the top electrode layer 170 (e.g., TCO) and the top metal pattern 181 (e.g., including the fingers 180 and the busbars 185) can then be completed.

[0053] In other embodiments, the perovskite subcell 220B is not patterned into a flange. For example, in some configurations, it may not be necessary to pattern the perovskite subcell, but it may still be necessary to pattern the front / back emitters and recombination layers.

[0054] In other embodiments, only the perovskite or silicon layer is patterned, or only the silicon layer is patterned. Solar cells according to embodiments are contemplated in which a tandem structure is formed without a lateral conductive recombination layer.

[0055] Figure 7 is a schematic cross-sectional side view illustration of a pair of overlapping tandem solar cells connected along patterned sub-cell flanges according to one embodiment. Figure 7 It can be basically similar to Figure 5 , one difference being that the recombined layer 355 is not laterally conductive. In such embodiments, there is no need to form the second patterned line opening (P2), and the recombined layer 355 can span and at least partially fill the first patterned line opening (P1). Similar to Figure 5 In an embodiment of the present invention, the perovskite subcell 220B can be removed at the mechanical connection point defining the contact flange. It should be understood that other conductive bonding materials including solder, solder paste, etc. can be used in place of the ECA 190 with such a contact flange 195 arrangement while still relieving stress on the upper perovskite subcell 220B.

[0056] Figure 8is a schematic cross-sectional side view illustration of a pair of overlapping tandem solar cells according to one embodiment. In such embodiments, the overlapping tandem solar cells 115 can be stacked from front to back without removing the top subcell 220B (e.g., perovskite). As with the previous embodiments, a busbar 185 can be optionally formed to enhance contact with the ECA 190. The busbar 185 can be formed as part of the same layer as the metal fingers 180 or as a separate layer. In one embodiment, the solar cell module includes a first transparent top electrode layer 170 above the first upper perovskite subcell 220B and a first top metal pattern 181 spanning the first transparent top electrode layer 170, the first top metal pattern including a plurality of metal fingers 180 and a busbar 185 adjacent to the lateral edge 117 of the first tandem solar cell. The back side 221 of the second tandem solar cell 115B is bonded to the busbar 185 with the ECA 190. In the illustrated embodiment, the first tandem solar cell 115A includes a first patterned line opening (P1) through the top surface of the first lower silicon subcell 220A. The busbar 185 is parallel to P1, and the busbar 185 can be positioned substantially laterally adjacent to the first lateral edge 349 of P1. For example, the first lateral edge 349 can be the edge of P1 that is closest to the lateral edge 117 of the first tandem solar cell 115A. This configuration can reduce the overlapping area of ​​the active areas of the tandem solar cells. In one embodiment, the first tandem solar cell 115 also includes a recombination layer 355 between the first lower silicon subcell 220A and the first upper perovskite subcell 220B, and a second patterned line opening (P2) through the recombination layer, so that P2 is directly above P1 and is wider than P1.

[0057] While ECA 190 has thus far been described with respect to bonding tandem solar cells to one another, ECA 190, particularly a solid ECA such as a tape, may be used to bond busbars 185 (eg, such as flat metal tape) to underlying structures. Fig. 9 is a schematic top view illustration of a cell bus bar 185 according to one embodiment. As shown, the tandem solar cells 115 may include fingers 180 formed using conventional deposition techniques for the tandem solar cells 115. This may be followed by bonding the cell bus bar 185 (e.g., a flat metal ribbon) using a solid ECA 190. In this manner, a plurality of tandem solar cells 115 may be connected to one another. In one embodiment, a solar cell module includes: a first tandem solar cell including a first plurality of metal fingers; a second tandem solar cell including a second plurality of metal fingers; and a bus bar bonded to the first plurality of metal fingers with a conductive adhesive material and bonded to the back of the second tandem solar cell with a second conductive adhesive material, and so on, for additional connections.

[0058] When utilizing various aspects of the embodiments, it will be apparent to those skilled in the art that combinations or variations of the above embodiments are possible for forming a solar cell module having overlapping tandem solar cells. Although embodiments have been described herein with respect to silicon-perovskite tandem solar cells, this is exemplary and the embodiments may be applied to alternative tandem solar cell compositions. Although embodiments have been described in language specific to structural features and / or method actions, it should be understood that the appended claims are not necessarily limited to the specific features or actions described. The specific features and actions disclosed should be understood as embodiments of the claims that can be used for illustration.

Claims

1. A solar cell module, comprising: A first series-connected solar cell, the first series-connected solar cell comprising: a first lower silicon subcell; a first upper perovskite subcell patterned to form a contact ledge over the first lower silicon subcell; A second series-connected solar cell, the second series-connected solar cell comprising: a second lower silicon subcell; second upper perovskite subcell; The back side of the second lower silicon subcell is bonded to the contact flange using a conductive adhesive material. 2 . The solar cell module according to claim 1 , wherein the conductive adhesive material is a solder material. 3 . The solar cell module of claim 1 , wherein the conductive bonding material is a conductive adhesive layer comprising a conductive material within a polymer matrix. 4 . The solar cell module of claim 1 , further comprising a recombination layer between the first lower silicon subcell and the first upper perovskite subcell. 5 . The solar cell module of claim 4 , further comprising a first transparent top electrode layer over the first upper perovskite subcell. The solar cell module of claim 5 , wherein the first transparent top electrode layer does not completely span across the contact flange. 7 . The solar cell module according to claim 5 , further comprising a first top metal pattern spanning the first transparent top electrode layer and the recombined layer on the contact flange to form a bus bar on the contact flange.

8. The solar cell module of claim 7, wherein the back surface of the second lower silicon subcell is bonded to the bus bar with the conductive bonding material, wherein the conductive bonding material is a conductive adhesive layer.

9. The solar cell module of claim 8, further comprising a first patterned line opening (P1) passing through a top surface of the first lower silicon subcell. 10 . The solar cell module according to claim 9 , further comprising a second patterned line opening ( P2 ) passing through the recombination layer, wherein the P2 is directly above the P1 and is wider than the P1 .

11. A method for assembling a solar cell module, the method comprising: The back side of the second tandem solar cell is bonded to the front side of the first tandem solar cell with a conductive adhesive tape.

12. The method according to claim 11: wherein the first tandem solar cell comprises a first lower silicon subcell and a first upper perovskite subcell, the first upper perovskite subcell being patterned to form a contact flange over the first lower silicon subcell; and Bonding the back side of the second tandem solar cell includes bonding the back side of the second tandem solar cell to the contact flange with the conductive adhesive tape.

13. A solar cell module, comprising: a first solar cell comprising a first plurality of metal fingers; and A bus bar is bonded to the first plurality of metal fingers with a conductive adhesive material.

14. The solar cell module of claim 13, further comprising a second tandem solar cell, the second tandem solar cell comprising a second plurality of fingers, wherein the bus bar is bonded to a back side of the second tandem solar cell with a second conductive adhesive material.

15. A solar cell module, comprising: A first series-connected solar cell, the first series-connected solar cell comprising: a first lower silicon subcell; The first upper perovskite subcell; a top electrode layer over the first upper perovskite subcell; a top metal pattern over the top electrode layer; A second series-connected solar cell, the second series-connected solar cell comprising: a second lower silicon subcell; second upper perovskite subcell; a back contact on a bottom surface of the second lower silicon subcell; wherein the back contact of the second tandem solar cell is bonded to the top metal pattern of the first tandem solar cell with a conductive adhesive layer.

16. The solar cell module according to claim 15, further comprising: a first transparent top electrode layer over the first upper perovskite subcell; as well as A first top metal pattern spanning the first transparent top electrode layer includes a plurality of metal fingers and busbars adjacent to lateral edges of the first tandem solar cell. 17 . The solar cell module of claim 16 , wherein the back surface of the second tandem solar cell is bonded to the bus bar with the conductive adhesive layer.

18. The solar cell module of claim 17, further comprising a first patterned line opening (P1) through the top surface of the first lower silicon subcell, wherein the busbar is parallel to the P1 and the busbar is positioned substantially laterally adjacent to a first lateral edge of the P1.

19. The solar cell module of claim 18, further comprising a recombination layer between the first lower silicon subcell and the first upper perovskite subcell. 20 . The solar cell module of claim 19 , further comprising a second patterned line opening ( P2 ) passing through the recombination layer, wherein the P2 is directly above the P1 and is wider than the P1 .

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