Stacked solar cell module

Abstract

Stacked solar cell module (5) comprising at least two stacked solar cells (1, 1', 1a-1d), • where each of the stacked solar cells (1, 1', 1a-1d) - a backside contact layer (10), a group of central layers (20, 30, 40) and an upper contact layer (50), wherein the group of central layers (20, 30, 40) comprises at least two partial solar cells (20, 40) with at least one absorber layer each, and at least one conductive intermediate layer (30) is arranged between each of two partial solar cells (20, 40) and - in the back contact layer (10) has an insulating segment (60) that electrically separates the back contact layer (10), so that sections (10_1, 10_1', 10_2) are formed and - has a layer insulator (70) in the conductive intermediate layer (30) and - a cross-layer conductor (90) comprising the group of central layers (20, 30, 40) and electrically connecting the upper contact layer (50) to a section (10_1, 10_1', 10_2) of the back-side contact layer (10) and • wherein the individual stacked solar cells (1, 1' 1a-1d) in the stacked solar cell module (5) are separated from each other by cell separators (80) extending from and encompassing the upper contact layer (50) to and encompassing the layer of a partial solar cell (20) nearest to and encompassing the backside contact layer (10), and wherein for a stacked solar cell (1, 1', 1a-1d) at the end of a row in the stacked solar cell module (5) the cell separator (80) is given by the end of the module (5) and • wherein in each stacked solar cell (1, 1', 1a-1d) the layer-spanning conductor (90) is arranged between the layer insulator (70) and a cell separator (80) and • Two adjacent stacked solar cells (1, 1', 1a-1d) are electrically connected via a section of the backside contact layer (10_1, 10_1', 10_2) extending from one stacked solar cell (1, 1', 1a-1d) to the next, characterized in that the stacked solar cells are designed as tandem solar cells with CIGS and perovskite as absorbers and the layer-spanning conductor (90) is formed from segments (92, 94).

Description

[0001] The invention relates to a stacked solar cell module.

[0002] A solar cell module, also called a solar module, comprises at least two solar cells, which can also be so-called stacked solar cells.

[0003] The term "in series" is used synonymously with the term "series circuit", borrowed from the English "series circuit", and refers to a circuit in which components are connected one after the other so that they form a single current path.

[0004] A solar cell is a device configured to convert light energy into electrical energy. A solar cell generally comprises at least one light-absorbing layer made of a light-absorbing material. This material absorbs incident photons, the energy of which converts the charge carriers in the material into an excited state. Such a material can be a semiconductor. To convert the resulting charge carriers into an electric current, an electric field is generally required, which can be generated, for example, by a pn junction. The pn junction is usually implemented by at least one additional layer or by steps within the material. In organic solar cells, the generation of so-called excitons in the organic absorber material also makes it possible to implement a single layer without a spatially separated pn junction.In addition, each solar cell requires at least functional electrical contacts (electrodes), usually implemented as layers. Further functional layers, e.g., to prevent recombination, buffer layers, and those to improve reflection properties, may be added.

[0005] A solar cell thus converts light energy into free charge carriers, i.e., an electric current.

[0006] A critical property of a solar cell is its efficiency, particularly its energy conversion efficiency. Solar cell efficiency is defined as the fraction of incident sunlight that is converted into electrical energy, which can then be used to perform work. Energy conversion efficiency is the ratio of energy input to electrical energy output. The energy conversion efficiency of a solar cell depends strongly on the light-absorbing material used in the cell or its overall composition.

[0007] In recent years, various approaches to increasing the energy conversion efficiency of a solar cell have been described. The development of solar cell technologies and the improvement in energy conversion efficiency can be tracked in "Solar cell efficiency tables" (published twice a year in "Progress in Photovoltaics" since 1993; latest publication: "Solar cell efficiency tables (version 55)," Green, MA et al. (2019); Prog. Photovolt. 28, 3-15).

[0008] One approach to increasing energy conversion efficiency involves so-called "multijunction" solar cells, also known as stacked solar cells, which consist of at least two sub-solar cells. Accordingly, a stacked solar cell comprises at least two sub-solar cells arranged one above the other, each containing light-absorbing layers, also called absorber layers, and any additional layers required to create pn junctions and electrodes. The materials of these at least two absorber layers in a stacked solar cell are usually different from each other.Advantageously, each material of an absorber layer is selected to absorb light in a specific wavelength range that complements the absorption range of the materials in the other absorber layers, so that overall, compared to a single solar cell, a larger portion of the incident light spectrum is utilized. In stacked solar cells, individual layers, e.g., conductive interlayers arranged between individual sub-solar cells, can be functionally attributed to two sub-solar cells each, and in the case of lower and upper contact layers, also functionally to the entire stacked solar cell.

[0009] In US patent 2018 / 0166504A1, among other things, a tandem solar cell is disclosed in which the upper sub-solar cell has a perovskite absorber with composition A 1-x A' x BX 3-y X' y comprising, where A is a formamidinium cation (HC(NH) z ) 2+), A' a cesium cation (Cs + ), B is at least one bivalent inorganic cation, X is iodide and X' is bromide, and where 0 < x ≤ 0.4 and 0 < y ≤ 3. The lower subcell comprises a copper indium gallium (di)selenide (CIGS) absorber.

[0010] In the case of stacked solar cell modules known from the prior art, and especially the common tandem solar cell modules, a problem arises when connecting several stacked solar cells: due to the stacking and the resulting electrical layout, the solar cells in a solar cell module cannot be connected in series via a monolithic electrical connection, as reported, for example, in the review article by Z. Li et al. (Scalable fabrication of perovskite solar cells, Nature Reviews | Materials, Vol. 3, 2018, 18017_1-20) for simple solar cells. Instead, a separate electrical connection must be installed. Series connection is preferable because otherwise high electrical currents occur, as the electrical currents of the connected individual solar cells add up, while the total voltage of a parallel-connected solar module remains constant.These relatively high electrical currents in the solar modules lead to dissipative heat losses, which should be avoided.

[0011] For the purposes of the invention, monolithic electrical connection means that the electrical connection is processed in one piece, i.e. from a block or wafer or piece.

[0012] The object of the invention is to provide a monolithic electrically series-connected stacked solar cell module that can be manufactured in a simple and cost-effective manner, and the associated method.

[0013] The problem is solved by the stacked solar cell module according to claim 1. Advantageous embodiments are specified in the dependent subclaims.

[0014] A stacked solar cell in a stacked solar cell module according to the invention comprises several layers, each layer having a lateral direction of extension (i.e., extension in the plane of the layer). The following layers are provided as a minimum: - a backside contact layer, - a group of central strata, and - an upper contact layer.

[0015] The group of central layers comprises at least two partial solar cells, each with at least one absorber layer and any additional functional layers required, wherein at least one conductive intermediate layer is arranged between each pair of partial solar cells.

[0016] The upper contact layer determines the side of the stacked solar cell facing the incidence of light, which also determines the side to be referred to as the upper side of the stacked solar cell - and also of a stacked solar cell module.

[0017] According to the invention, in a stacked solar cell of the stacked solar cell module, the back contact layer is divided into two sections, distinguishable from each other in a stacked solar cell, by an insulating segment, wherein the electrical conductivity of the insulating segment is lower than the conductivity of the back contact layer, so that the insulating segment electrically isolates the sections of the back contact layer from each other.

[0018] According to the invention, a conductor extending across layers is arranged in the group of central layers of each stacked solar cell of the stacked solar cell module. This conductor extends through or encompasses the individual layers of the group of central layers and electrically connects the upper contact layer and one of the two sections – per stacked solar cell – of the backside contact layer, thus forming a current path from the upper contact layer to this section of the backside contact layer. The conductivity of the conductor extending across layers is at least as high as that of the individual conductive intermediate layers and higher than that of the other layers through which it extends.

[0019] In addition, according to the invention, each conductive intermediate layer of a stacked solar cell of the stacked solar cell module is divided into two subsections by a layer insulator, which are consequently electrically isolated from each other. The electrical conductivity of the layer insulator is lower than that of the conductive intermediate layer, so that the conductive intermediate layer is separated into two electrically isolated subsections.

[0020] Furthermore, according to the invention, two adjacent stacked solar cells are electrically connected to each other via a section of the back contact layer extending from one stacked solar cell to the next, so that the stacked solar cells in the stacked solar cell module are connected in series via a monolithic electrical connection. The electrical connection is formed in one piece or monolithically.

[0021] The individual stacked solar cells of the stacked solar cell module are separated from each other by cell separators. These separators extend through the upper contact layers to the lowest layer of a sub-solar cell, i.e., the layer closest to the back contact layer, and terminate before reaching the back contact layer. The cell separators are arranged regularly, such that an insulating segment of the back contact layer, a conductor spanning multiple layers, and a layer insulator for each conductive intermediate layer of the stacked solar cells are completely located between two cell separators. Consequently, the area between each pair of cell separators forms a stacked solar cell. In the limiting case where a stacked solar cell is located at the edge, i.e., at the end of a series of stacked solar cells in a stacked solar cell module, the cell separator is omitted on the end side or is formed by the end of the module.Each stacked solar cell is assigned a cell separator, and for a terminal stacked solar cell in a row of stacked solar cells, the end of the module serves as a cell separator instead of a cell separator.

[0022] The insulating segments, the layer insulators, the cross-layer conductors and the cell separators are regularly spaced apart from each other at a first distance.

[0023] Within the stacked solar cells thus formed in the stacked solar cell module, the arrangement of the insulating segment in the back contact layer, the layer insulators or the layer insulator and the cross-layer conductor to each other is as follows for each stacked solar cell.

[0024] An insulating segment in the backside contact layer of a stacked solar cell divides the backside contact layer into two distinct sections within the stacked solar cell. The cross-layer conductor of a stacked solar cell is positioned to connect the upper contact layer to one of the two sections of the backside contact layer of the stacked solar cell within the module. This cross-layer conductor is located between the layer insulator and a cell separator associated with the respective stacked solar cell. The area between the cross-layer conductor and this cell separator must be minimized, as it is largely uninvolved in the current flow within the stacked solar cell and therefore also in its efficiency. This means, in the same sense, that the distance between the cross-layer conductor and the cell separator, and vice versa, must be minimized.The layer insulators in the conductive intermediate layers prevent a short circuit between the conductor across the layers and the part of the stacked solar cell that actively contributes to the current flow within the stacked solar cell. The distances between the layer insulators and the conductor across the layers must therefore also be minimized to reduce losses. The position of the layer insulators is determined by their function, with the layer insulators located on the side of the conductor facing away from the cell separator. In other words, according to the invention, the layer insulators prevent the flow of free charge carriers between the subsections of the conductive intermediate layer formed by the layer insulators, thus forcing the charge carriers to first flow into a contact layer belonging to the stacked solar cell, from where they are directed via the conductor across the layers.The cross-layer conductor, in conjunction with the layer insulator, thus causes a current or charge carrier flow in a stacked solar cell that is perpendicular to the layers and especially to the conductive intermediate layers.

[0025] This arrangement within a stacked solar cell in the stacked solar cell module ensures that the flow of generated charge carriers in the stacked solar cell is channeled, with the flow predominantly and preferentially passing through the upper contact layer and the interlayer conductor to the second section of the backside contact layer. The direction of the flow depends on the design of the stacked solar cell. This channeling of the charge carrier flow provides the output voltage in the backside contact layer of the stacked solar cells. The potential difference between the sections of the backside contact layer essentially constitutes the output voltage of such a stacked solar cell in operating mode, i.e., when charge carriers are generated in the absorber layers.In the stacked solar cell module according to the invention, the individual stacked solar cells can be manufactured monolithically and electrically connected in series, so that a resulting total voltage is provided or can be tapped at a backside contact layer, in particular at a respective marginal section of the backside contact layer in the stacked solar cell module.

[0026] A solar cell is a three-dimensional object. By definition, it has a horizontal (lateral) direction of extension, defined by an x-axis and a y-axis. Perpendicular to this (vertically), the solar module extends along the z-axis, which corresponds to the stacking direction of the layers.

[0027] The insulating segments in the backside contact layers, the layer insulators of the conductive intermediate layers, the cell separators and the cross-layer conductors, in addition to extending along the stacking direction of the layers, the z-axis, also have an extension in the direction of the x-axis, with a comparatively small extension in the direction of the y-axis.

[0028] The x-axis is defined by the regular extent of the insulating segments in the backside contact layers, which form ribs in the backside contact layers.

[0029] Each layer has a layer thickness that extends along the z-axis (vertically),

[0030] The term "layer" refers specifically to a three-dimensional body that is essentially defined and bounded by two opposite sides (surfaces) and extends in a plane (laterally, here the x, y-plane). A layer is formed from at least one material. It is obvious that due to manufacturing tolerances, a layer can exhibit waviness and surface roughness and is not necessarily perfectly planar or flat.

[0031] It is noted that further layers may be arranged between some of the disclosed layers, comprising different or identical materials; this list is not exhaustive. Examples of further possible layer sequences are detailed below.

[0032] Electrical conductivity is a property of a material relating to its ability to conduct an electric current, i.e., its capacity to possess free charge carriers such as electrons or holes. The greater (or higher) the electrical conductivity of the material, the better it can conduct electric current. The electrical conductivity, or lack thereof, also determines the specific resistance of a material.

[0033] The term "electrically isolated" from another section or subsection means, in particular, that the electrical conductivity of the corresponding insulation or insulating segment is significantly lower (resistance > 10 Ω). 8 Ω·cm) as the electrical conductivity of the adjacent sections of the layers and especially also with respect to the layers adjacent in the z-direction.

[0034] According to the invention, the group of central layers, as already introduced above, comprises a cross-layer conductor that extends through the layers of the group of central layers and through the second subsection of the conductive intermediate layer. According to the invention, the cross-layer conductor is divided into segments. This is achieved, for example, by each individual sub-solar cell comprising a conductive segment and by each conductive intermediate layer comprising a conductive segment. The conductive segments are arranged one above the other in the layer stack formed from the central layers in the direction of the z-axis. The segments are not necessarily limited to a single layer each, but can, for example, also extend over the layers of a sub-solar cell and a conductive intermediate layer, i.e., they can partially cross layers. The conductive segments, orThe cross-layer conductor formed from them extends along the x-axis in addition to its extension perpendicular to the stacking direction and has a width that extends along the y-axis.

[0035] The cross-layer conductor or conductive segments are arranged such that the upper contact layer is electrically connected to a section of the backside contact layer.

[0036] The resulting current flow, which, as described above, provides the output voltage of the stacked solar cells in the back contact layer, allows for the monolithic series connection of several stacked solar cells within the module. This leads to an increase in voltage rather than an increase in electric current, which is an advantage of the invention. Furthermore, the current flow in the individual sub-solar cells of the stacked solar cells is not divided; in other words, the sub-solar cells of the stacked solar cells are also connected in series. This, in turn, enables the inventive series connection of several stacked solar cells according to the invention within a single module, thereby increasing efficiency by reducing losses.

[0037] The electrical conductivity of the cross-layer conductor or conductive segments is, in particular, greater than the electrical conductivity of the layers in the group of central layers, except for the conductivity of the conductive intermediate layer, which is at least equal to or greater than the cross-layer conductor. The cross-layer conductor, optionally composed of the conductive segments in the layers, ensures that the charge carrier flow from the upper contact layer to the back-side contact layer occurs predominantly through the conductor and is thus channeled.

[0038] The upper contact layer is at least translucent and, in particular, transparent to sunlight.

[0039] The conductive intermediate layer is also at least translucent and, in particular, transparent to sunlight.

[0040] The following layers, as known from the prior art, can be arranged in individual sub-solar cells to complete them: buffer layers between the absorber layers and the conductive intermediate layers, as well as intrinsic layers between the absorber layers and the conductive intermediate layers.

[0041] The buffer layers can include an n-buffer and, in the case of perovskite tandem solar cells, consist of, for example, cadmium sulfide (CdS), zinc oxide (ZnO) or zinc sulfide (ZnS).

[0042] The intrinsic layers can comprise or consist of intrinsic zinc oxide (i-ZnO). Other materials with comparable conductivity and transparency properties are also possible for the formation of intrinsic layers.

[0043] These additional layers are also captured by the cross-layer conductor and the cell separator.

[0044] The stacked solar cells of the stacked solar cell module according to the invention are tandem solar cells.

[0045] In a first embodiment, the lower layer of each sub-solar cell of the tandem solar cells, i.e., the layer closest to the backside contact layer, is locally integrally connected to the backside contact layer. This means that the backside contact layer, which is in particular a metal layer, is directly bonded to the surface of the lower layer facing it. In other words, the connection is made without the intermediate placement of any additional materials, such as low-melting-point solder. In this embodiment of the tandem solar cell, this also applies to the connection of the conductive intermediate layer to the lowermost layer of the upper sub-solar cell and of the upper contact layer to the upper layer of this sub-solar cell. This form of integral connection is also referred to as a positive contact within the meaning of the invention.This embodiment can also be referred to as a monolithic tandem solar cell (made from a single block).

[0046] According to a second embodiment, the backside contact layer comprises a metal, in particular a transition metal, specifically a metal from the group consisting of molybdenum, tungsten, chromium, tantalum, niobium, vanadium, titanium, and manganese. The backside contact layer is advantageously arranged on glass substrates.

[0047] Absorber layers or an absorber material comprising them for a partial solar cell of a stacked solar cell advantageously consist of a semiconductor material, which is in particular one from the group of compounds of copper, indium, gallium, and selenium or of copper, indium, gallium, and sulfur or copper indium gallium (di)selenide or copper indium gallium (di)sulfide (Cu(In,Ga)(S,Se)2) or CdTe.

[0048] In the context of this application, copper indium gallium (di)selenide is also referred to as CIGS.

[0049] The conductive intermediate layers can comprise a first transparent conductive oxide, wherein this comprises or consists of, for example, one of the materials from the group aluminum-doped zinc oxide, CuO2, ZnMgO:Al, Zn(S,O):Al, Zn:B, ZnO:B, indium oxide (ITO), tin-doped indium oxide or hydrogenated indium oxide (IOH), and in particular is aluminum-doped zinc oxide.

[0050] The upper absorber layer of the upper partial solar cell in tandem solar cell design is made of perovskite.

[0051] The upper contact layers are formed from or comprise a second transparent conductive oxide, which is in particular indium zinc oxide.

[0052] The lower solar cell component in a tandem solar cell configuration can include an n-buffer positioned on the side of the absorber layer facing away from the backside contact layer. The n-buffer can be composed of cadmium sulfide (CdS) ZnO or ZnS. Alternatively, the lower solar cell component can also include an intrinsic zinc oxide (i-ZnO) layer positioned on the side of the absorber layer facing away from the backside contact layer. The intrinsic zinc oxide layer can also be positioned on top of the n-buffer, on the side facing away from the backside contact layer.

[0053] Advantageously, the cross-layer conductors each comprise an upper and a lower boundary layer, the upper boundary layers bordering the upper contact layers and the lower boundary layers bordering the backside contact layers. The upper boundary layers comprise a first conductive material and the lower boundary layers a second conductive material. The first conductive material is, in particular, a transparent conductive oxide, e.g., indium zinc oxide or a related material. The second conductive material is, in particular, a laser-transformed copper chalcogenide or copper indium gallium (di)sulfide or a related material. The upper and lower boundary layers are electrically connected to each other via the cross-layer conductor. The first conductive material is advantageously formed from the material of the upper contact layer.

[0054] The insulating segments in the backside contact layers are formed in particular from the material of the absorber layer initially arranged on them. The layer insulators are formed in particular from the material of the absorber layers deposited on them.

[0055] The stacked solar cell module according to the invention is formed from at least two stacked solar cells according to the invention, as described above. According to the invention, each stacked solar cell is electrically connected to an adjacent stacked solar cell via a section of its backside contact layer, and the electrical connection is thus formed integrally. It must be ensured that the currents of the stacked solar cells and the individual solar cells are matched to each other according to the series connection.

[0056] This interconnection of the tandem solar cells according to the invention into a module results in the tandem solar cells being monolithically connected in series within the module, meaning there is only one current path in the module. This is advantageously implemented here, so that the currents of the individual cells do not add up and heat losses are reduced, which in turn increases efficiency. Furthermore, the possibility of monolithic design of the cell connections is advantageous, as it simplifies manufacturing. The design of the current flow in the tandem solar cells according to the invention is a prerequisite for the series connection of the tandem solar cells in the module according to the invention.

[0057] Due to the series connection, the current in each tandem solar cell of the module is the same, while the total voltage of the module results from the sum of the partial voltages of the individual tandem solar cells in the module.

[0058] A method for manufacturing a stacked solar cell module or a module according to the invention is given below.

[0059] The procedure includes at least the following steps: 1. Providing a backside contact layer or depositing a backside contact layer on a substrate; 2. Generating insulating segments in the backside contact layer, which extend along a first direction in the backside contact layer which forms the x-axis and which are arranged at regular first intervals perpendicular to the x-axis; 3. Deposition of the layers of a partial solar cell, which includes at least one absorber layer; 4. Deposition of a conductive intermediate layer; 5. Producing layer insulators in the conductive intermediate layer extending along the x-axis, in particular by a selective laser ablation process or by a photolithography process, and arranged regularly at intervals corresponding to the first intervals, perpendicular to the x-axis; 6. Repeat steps 3 to 5 until the layers of a final partial solar cell are deposited, after which steps 4 and 5 are omitted; 7. Generating cross-layer conductors encompassing the last deposited layer and extending from it to the backside contact layer, in particular by a laser ablation process, extending along the x-axis and at regular intervals perpendicular to the x-axis corresponding to the first intervals, wherein the cross-layer conductor is formed from segments that can be introduced per layer after their respective deposition in steps 3, 4 and 5, or also cross-layer after the deposition of at least two of the layers in question, and wherein the segments are arranged one above the other along a stacking direction of the layers, and wherein each segment or each entire cross-layer conductor is filled with a material having a conductivity greater than or equal to the highest conductivity in the layers; 8. Deposition of an upper contact layer; 9. Generating cell separators extending along the x-axis from the upper contact layer including the layer of a partial solar cell first arranged in the back contact layer, in particular by mechanical scoring and at regular intervals perpendicular to the x-axis corresponding to the first intervals, such that an insulating segment, a layer insulator and a cross-layer conductor are arranged between the cell separators in each stacked solar cell formed in this way, and wherein the cross-layer conductor is arranged between the layer insulators and the cell separators or, in the case of a stacked solar cell terminal in a row of the module, at the end of the stacked solar cell module.

[0060] The insulating segments, layer insulators, and cell separators are created by producing trenches or incisions in the layers using laser ablation or other methods. Advantageously, these areas are further enhanced in their insulating function by filling them with an electrically insulating material following the respective production steps. This insulating material has an electrical conductivity lower than the conductivity of the layers themselves, and in particular, such a low conductivity that the material can be classified as an electrical insulator (resistance > 10 Ω). 8 Ω·cm). In particular, this material consists of the materials of the absorbers.

[0061] The back contact layer can be deposited onto a substrate. In particular, the back contact layer can be applied to the substrate by, for example, sputtering, vapor deposition, or electroplating.

[0062] An absorber layer can be deposited, for example, by the processes of so-called "In-Line RTP" (Rapid Thermal Annealing) and co-evaporation.

[0063] The conductive intermediate layers can be deposited onto absorber layers, for example, by sputtering (cathode sputtering).

[0064] An absorber layer can, for example, be a perovskite layer and be deposited onto a conductive intermediate layer using a spin-coating process.

[0065] The upper contact layers can be deposited, for example, by sputtering on a perovskite layer.

[0066] The procedure can be advantageously designed by the following combinable additional steps: - Deposition of absorber material into the insulating segment in the backside contact layers in step 3. - Creating a lower boundary layer for contact of the cross-layer conductors with the backside contact layers on the same after step 3 by depositing the absorber layer and by transforming the absorber layer with a light, in particular using a laser. - Deposition of the material from absorber layers in the layer insulators in step 6. - Deposition of the upper contact layer, step 8, and thereby filling the conductors or their segments across the layers with the conductive material of the upper contact layer.

[0067] The invention is explained in more detail below with reference to two figures and exemplary embodiments.

[0068] The figures show: Fig. 1 Schematic cross-sectional view of a section of a stacked solar cell module according to the invention; Fig. 2 Schematic cross-sectional view of a stacked solar cell module according to the invention in detail with two tandem solar cells.

[0069] A section of a stacked solar cell module according to the invention, comprising a complete stacked solar cell 1 and an adjacent, only partially shown, further stacked solar cell 1', is shown in Fig. 1 shown. The stacked solar cell module of the Fig. 1 and Fig. Figure 2 corresponds to the embodiment of a tandem solar cell module. In the Fig. The tandem solar cells 1, 1' in module 1 comprise several layers or layer sequences of the sub-solar cells (10, 20, 30, 40, 50). The layer planes are spanned by or parallel to the x- and y-axes (the axis system is shown in the lower right). Perpendicular to this, in the stacking direction of the layers, lies the z-axis. The x-axis is shown in the view of the Fig. 1 is oriented perpendicular to the plane of the drawing and is characterized by the fact that the insulating segment 60 in the backside contact layer 10 and the layer insulator 70 in the conductive intermediate layer 30, the cell separator 80 and the cross-layer conductor 90 extend along the direction of the x-axis through the entire extent in the direction of the x-axis of the respective layer.

[0070] The tandem solar cell 1 of the Fig. 1 has a backside contact layer 10, a partial solar cell 20, a conductive intermediate layer 30, a second partial solar cell 40 and an upper contact layer 50.

[0071] The insulating segment 60 is arranged in the backside contact layer 10, and the layer insulator 70 is arranged in the conductive intermediate layer. The insulating segment 60 divides the backside contact layer 10 into two sections, which are designated as a first section 10_1 and a second section 10_2 within a stacked solar cell. In the exemplary embodiment, the cross-layer conductor 90 is formed from two segments 92 and 94, wherein a lower segment (facing the backside contact layer) is arranged across the sub-solar cell 20 and the conductive intermediate layer 30, and an upper segment 94 is arranged in the direction of the z-axis directly above the lower segment in the upper sub-solar cell 40.Between the upper segment 94 of the cross-layer conductor 90 and the upper contact layer 50, an upper interface 98 made of a conductive material is formed, and between the lower segment 92 and the backside contact layer 10, a lower interface 96 is formed. The cell separator 80 is arranged such that the upper contact layer 50, the upper sub-solar cell 40, the conductive intermediate layer 30, and the lower sub-solar cell 20 are separated and electrically insulated from the layers of the adjacent tandem solar cell 1', thus forming two tandem solar cells 1, 1' (second cell 1' shown only partially).The current flow according to the invention is realized in the stacked solar cell, here in this example a tandem solar cell, by arranging the cross-layer conductor 90 between the cell separator 80 and the layer insulator 70 and by connecting the cross-layer conductor 90 of the upper contact layer 50 with one of the sections formed by the insulating segment 60 in the backside contact layer. Due to the interaction of the insulating segment 60 with the layer insulator 70, the cell separator 80, and the cross-layer conductor 90, and their arrangement relative to each other, a voltage is present between the first 10_1 and second section 10_2 of the backside contact layer via the current path formed thereby.

[0072] In the Fig. Figure 1 also shows the current path in the stacked solar cell according to the invention, in this example a tandem solar cell, indicated by the arrows, and additionally, in the lower 20 and upper 40 sub-solar cells, the free charge carriers generated by light absorption, shown as circles flowing along the current path. The two sub-solar cells in the tandem solar cell are themselves also connected in series.

[0073] Fig. Figure 2 shows a larger section of the tandem solar cell module 5 according to the invention. The section of the tandem solar cell module 5 shown comprises a first 1a, only partially shown, two further tandem solar cells 1b, 1c, and, at the outer right edge, a further tandem solar cell 1d, also only partially shown. The cell separators 80a, 80b, and 80c are each assigned to the tandem solar cells 1a, 1b, and 1c, respectively. The tandem solar cells 1a, 1b, 1c, and 1d shown here according to the first embodiment of the Fig. 1 executed. In the Fig. Figure 2 illustrates the principle of the series connection of the stacked solar cells in the stacked solar cell module and, in particular, the monolithic design of the electrical connection of the stacked solar cells. Each stacked solar cell 1a, 1b, 1c, 1d shares a section of the two sections of the backside contact layer 10 with the adjacent stacked solar cell, which can be distinguished as the first 10_1, 10_1' and second 10_2.

[0074] As from the Fig. As can also be seen in Figure 2, the voltages V1, V2 applied in the stacked solar cells 1a, 1b connected in series in the module, between their sections 10_1 and 10_1' in the back contact layer 10 add up to a total voltage Vt, while the generated electric current is essentially independent of the number of stacked solar cells, which gives rise to the advantage of the invention.

[0075] The explanatory procedure comprises the following steps: 1. Providing a molybdenum layer on a glass substrate as a backside contact layer 10 by sputtering the molybdenum onto the glass substrate. 2. Generating the insulating segments 60 in the backside contact layer 10, along a first extent which forms the x-axis, and at regular first intervals perpendicular to the x-axis by laser ablation (referred to as P1 in laboratory jargon). 3. Deposition of a CIGS layer as an absorber layer 20 on the backside contact layer 10, followed by the deposition of a CdS buffer layer as an additional layer and an i-ZnO intrinsic layer as a further additional layer. 4. Deposition of a ZnO:Al layer as a conductive intermediate layer 30. 4.a Generating cross-layer segments 92 of the cross-layer conductor 90 according to step 7 of the explanatory procedure, by laser transformation of the materials along the x-axis and at regular intervals corresponding to the first distance perpendicular to the x-axis in the layers previously deposited in steps 3 and 4 (referred to in laboratory jargon as P2(ns)). 5. Production of layer insulators 70 in the conductive intermediate layer 30 along the x-axis and at regular intervals corresponding to the first distance perpendicular to the x-axis by selective laser ablation (referred to as P3 in laboratory jargon). 6. Deposition of a perovskite layer and other functional layers to form a perovskite sub-solar cell 40. 7. Creation of a segment 94 of the cross-layer conductor 90 by mechanical scribing along the x-axis and at regular intervals perpendicular to the x-axis exactly above and along the cross-layer segments 92 of the cross-layer conductor 90 created in step 4a in the layers deposited in steps 5 and 6 (referred to in laboratory jargon as P2(ns)). 8. Deposition of an indium tin oxide layer as the upper contact layer 50 while simultaneously filling the segments 94 of the cross-layer conductor 90 created in step 7. 9. Generating cell separators 80 extending from the upper contact layer 50 inclusive to the lower layer, i.e., the backside contact layer 10, the layer closest to it, here the CIGS layer as absorber layer inclusive, along the x-axis, in particular by mechanical scribing (referred to as P4 in laboratory jargon) and at regular intervals corresponding to the first distance perpendicular to the x-axis, such that an insulating segment, a layer insulator and a cross-layer conductor are arranged between each of the cell separators and wherein the cross-layer conductor 90 is arranged between one of the cell separators 80 to be assigned to the solar cell in question and the layer insulator 70.

[0076] Accordingly, CIGSe perovskite tandem solar cells are a concrete example of the implementation of the stacked solar cells in the stacked solar cell module.

Claims

[1] Stacked solar cell module (5) comprising at least two stacked solar cells (1, 1', 1a-1d), • where each of the stacked solar cells (1, 1', 1a-1d) - a backside contact layer (10), a group of central layers (20, 30, 40) and an upper contact layer (50), wherein the group of central layers (20, 30, 40) comprises at least two partial solar cells (20, 40) with at least one absorber layer each, and at least one conductive intermediate layer (30) is arranged between each of two partial solar cells (20, 40) and - in the back contact layer (10) has an insulating segment (60) that electrically separates the back contact layer (10), so that sections (10_1, 10_1', 10_2) are formed and - has a layer insulator (70) in the conductive intermediate layer (30) and - a cross-layer conductor (90) comprising the group of central layers (20, 30, 40) and electrically connecting the upper contact layer (50) to a section (10_1, 10_1', 10_2) of the back-side contact layer (10) and • wherein the individual stacked solar cells (1, 1' 1a-1d) in the stacked solar cell module (5) are separated from each other by cell separators (80) extending from and encompassing the upper contact layer (50) to and encompassing the layer of a partial solar cell (20) nearest to and encompassing the backside contact layer (10), and wherein for a stacked solar cell (1, 1', 1a-1d) at the end of a row in the stacked solar cell module (5) the cell separator (80) is given by the end of the module (5) and • wherein in each stacked solar cell (1, 1', 1a-1d) the layer-spanning conductor (90) is arranged between the layer insulator (70) and a cell separator (80) and • each pair of adjacent stacked solar cells (1, 1', 1a-1d) are electrically connected via a section of the backside contact layer (10_1, 10_1', 10_2) extending from one stacked solar cell (1, 1', 1a-1d) to the next, characterized by , that the stacked solar cells are designed as tandem solar cells with CIGS and perovskite as absorber and the layer-spanning conductor (90) is formed from segments (92, 94). [2] Stacked solar cell module (5) according to claim 1, characterized by , that the tandem solar cells (1, 1', 1a-1d) are monolithic. [3] Stacked solar cell module (5) according to claim 1 or 2, characterized by , that the backside contact layer (10) comprises a metal, in particular a transition metal, in particular a metal from the group consisting of molybdenum, tungsten, chromium, tantalum, niobium, vanadium, titanium and manganese.

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