3t tandem solar cell, tandem solar cell module, and method for producing same
Patent Information
- Application Number
- EP2023720757
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-04-08
- Filing Date
- 2023-04-04
- Publication Date
- 2025-02-12
AI Technical Summary
The production of 3T tandem solar cells for solar cell modules is challenging, particularly with regards to the third electrode or connection, leading to reduced efficiency due to ohmic losses and limited side tapping capabilities in existing configurations.
A 3T tandem solar cell design featuring a connection layer with a one-piece electrically conductive line element that contacts multiple points on both transparent conductive layers, forming a third electrode and enabling efficient series connection and side tapping without selective doping, using an embedding agent for mechanical stability and reduced resistance.
This design enhances the production and efficiency of 3T tandem solar cells by reducing ohmic losses and allowing for reliable side tapping, enabling the quick and efficient production of 3T tandem solar cells and modules with improved mechanical stability and reduced cumulative contact resistance.
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Abstract
Description
[0001] 3T tandem solar cell, tandem solar cell module and method for manufacturing
[0002] The invention relates to a 3T tandem solar cell, in particular for interconnection in a solar cell module, a tandem solar cell module and a method for producing the 3T tandem solar cell.
[0003] Tandem solar cells are known in the art. A tandem solar cell comprises two solar cells—a first solar cell ("top cell") and a second solar cell ("bottom cell")—stacked one above the other. The first solar cell absorbs light in a different wavelength range than the second solar cell. This allows for more efficient energy harvesting in the wavelength range where sunlight can be converted into electrical energy.
[0004] Thin-film solar cells have become popular candidates for tandem solar cells because they can be manufactured using low-cost processes.
[0005] The first solar cell is usually contacted with a first electrode (“upper electrode”) and the second solar cell with a second electrode (“lower electrode”), which serve as (electrical) terminals (“T”), so that a so-called 2T tandem solar cell (2T from English: two terminals, German: two connections) is created.
[0006] Tandem solar cells are available in various configurations for interconnection or equipped with terminals for connecting or tapping current or voltage. In a so-called 2T tandem solar cell, the solar cells are connected in series, with the first and second electrodes serving as contacts that provide the electrical voltage to a terminal for tapping. In a so-called 4T tandem solar cell, each solar cell is separately contacted, and the electrical voltage and current for each cell are tapped individually, meaning each cell has a complementary electrode.
[0007] A third configuration is called a 3T tandem solar cell. This is constructed in such a way that a third electrode is provided as a connection through a connecting layer between the two solar cells, which contacts both the first and the second solar cell. 3T tandem solar cells are realized, for example, in the form of silicon perovskite tandem solar cells, in which the back contact can be divided into several contacts with selective n- or p-doping, e.g., as in so-called IBC (interdigitated back contact) interconnections. The main advantage of the 3T configuration is the ability to mechanically connect an upper and a lower solar cell, which enables lateral tapping of the current (or voltage) generated between the upper and lower solar cells (without selectively doping the lower solar cell).
[0008] However, the production of 3T tandem solar cells for a tandem solar cell module comprising a plurality of such 3T tandem solar cells, or at least two, is challenging, particularly with regard to the third electrode or terminal. Furthermore, it would be advantageous to connect several 3T tandem solar cells in series in one module.
[0009] This problem was partially addressed by Talysa R Klein et al. 2021 J. Phys. D: Appl. Phys. 54, 184002; https: / / doi.org / 10.1088 / 1361-6463 / abe2c4.
[0010] The authors of this article present a tandem solar cell comprising a first and a second solar cell with an interconnect layer arranged between the cells, wherein the interconnect layer includes a plurality of silver-coated spheres configured and arranged to contact the first and second solar cells. This type of contacting essentially enables a 3T tandem solar cell. However, each contact of a sphere with the first or second solar cell inevitably involves an ohmic resistance. In addition, since an electric current must traverse the contacts of the spheres with the contact layers of the first and second solar cells several times to reach the edge of the tandem solar cell, where the current can be tapped at a terminal, the efficiency of such a configuration is significantly reduced due to ohmic losses at the contacts of the spheres.Furthermore, this approach only allows for vertical tapping of an electrical current. Lateral tapping is not possible.
[0011] Therefore, there is a need for an improved tandem solar cell having a 3T configuration.
[0012] The problem is solved by a 3T tandem solar cell according to claim 1, a tandem solar cell module according to the inventive tandem solar cell according to claim 9, and a method for producing a tandem solar cell module according to claim 13. Advantageous embodiments are described in the dependent claims.
[0013] For the purposes of the invention and this description, the term "terminal" refers to a means for tapping a current or voltage from a tandem solar cell or a tandem solar cell module. This particularly applies to electrodes included in the 3T tandem solar cell and other means for conducting electrical current.
[0014] In the description of the invention, the term "electrode" refers to a means that is an electron conductor and interacts with a counter electrode (anode - cathode), whereby the electrodes are electrically contacted by an absorber arranged directly or indirectly between them. Electrodes can always be used as terminals ("T").
[0015] An absorber, as defined by the invention and this description, refers to a material that absorbs light and in which charge carriers are generated through absorption. To complete a solar cell, it is always considered to complete an absorber in a suitable manner for power generation, e.g., by means of a pn or pin junction, possibly by suitable doping, or, for example, by means of selective contacts.
[0016] Conductive is always used in the sense of electrically conductive and refers to an electrical conductivity of > 1 - 10 5 S / m.
[0017] The 3T tandem solar cells and tandem solar cell modules according to the invention are not limited by the following description and the patent claims to the statements made here regarding the intended layers. A design with additional functional layers is open to the person skilled in the art.
[0018] A first aspect of the invention relates to a 3T tandem solar cell comprising at least the following components: a first solar cell, at least comprising a first absorber layer arranged between a first electrode arranged on a side of the first solar cell that faces incident light during operation and a first transparent conductive layer arranged on a side of the first solar cell that faces away from the incident light during operation, a second solar cell comprising a second absorber layer arranged between a second electrode arranged on a side of the second solar cell that faces away from the incident light during operation and a second transparent conductive layer arranged on a side of the second solar cell that faces the incident light during operation,is arranged and a connecting layer arranged between the first and the second solar cell, wherein the connecting layer forms an electrically conductive connection between the first solar cell and the second solar cell in which the connecting layer comprises at least one electrically conductive, one-piece conducting element and wherein the at least one one-piece conducting element is embedded in an embedding medium while maintaining a plurality of contact points to the first and to the second transparent conductive layers, and wherein the at least one one-piece conducting element forms a third electrode of the 3T tandem solar cell or is connected thereto.
[0019] The 3T tandem solar cell according to the invention provides a robust improvement over the 3T tandem solar cells known from the prior art. The use of at least one integral conductive element embedded in the connecting layer, which on the one hand contacts the first and second solar cells via several contact points and on the other hand forms the third electrode or is connected to it, enables rapid and reliable production of the 3T tandem solar cell according to the invention.
[0020] The 3T tandem solar cell is, in particular, a thin-film tandem solar cell in which the absorber layers are implemented as thin films. Thin films are typically defined as layers in the range of a few nanometers (1 nm) to several tens of micrometers (50 pm).
[0021] The first electrode can be formed as a layer covering the first absorber layer. In this case, the first electrode, which faces the incident light during operation of the 3T tandem solar cell, is transparent. For example, the transparent first electrode can consist of or comprise indium zinc oxide (IZO) or another transparent conductive oxide (TCO).
[0022] Alternatively, the first electrode may not be transparent and consist of a metallic compound, for example, and in this case is not designed as a layer, so that light penetration into the 3T tandem solar cell is still ensured.
[0023] Similarly, the second electrode can be transparent, but can also comprise a metal or metal compound, such as molybdenum, which can also be implemented as contact fingers as an electrode. The second electrode can also be formed as a layer covering the second absorber layer on the side facing away from the incident light.
[0024] The first solar cell is configured to absorb light in a first wavelength range of the electromagnetic spectrum and to generate charge carriers in response to the absorption of the light. The second solar cell is configured to absorb light in a second wavelength range of the electromagnetic spectrum and to generate charge carriers in response to the absorption of the light. The first and second wavelength ranges are different from each other. In particular, the first wavelength range is blue-shifted relative to the second wavelength range. However, it may also be red-shifted relative to the second wavelength range.
[0025] The embedding medium is, for example, an electrically insulating polymer or, advantageously, an electrically insulating thermoplastic. All materials with a specific resistance of > 10 10 d em have.
[0026] The third electrode may be formed by a busbar connected to one or more ends of the at least one conducting element or elements, or may be formed by the at least one integral conducting element itself.
[0027] The at least one one-piece conductor element can be a metallic conductor element formed in a single piece. In particular, the conductor element can be formed as a wire, which can also be formed as a stranded wire with at least two individual wires. The arrangement of multiple wires or stranded wires is also encompassed by the invention.
[0028] The 3T tandem solar cell is interconnected in multiple versions, in particular to form a tandem solar module or is implemented directly in a tandem solar module, as also corresponds to a second aspect of the invention.
[0029] In particular, in a tandem solar cell module with more than one 3T tandem solar cell, the third electrode of the last 3T tandem solar cell in a row of tandem solar cells is accessible for external contacting and forms the third electrode there or can be contacted with such a third terminal in the solar module.
[0030] The at least one integral conduction element contacts the first and second solar cells in a 3T tandem solar cell through a plurality of (n > 2) contact points and enables an accessible third terminal. The contact points are retained when embedding the at least one integral conduction element.
[0031] The contact points can be of different sizes and, if necessary, their size and number can be optimized with regard to the resistance generated.
[0032] In the case that the third electrode of a 3T tandem solar cell is not the last third electrode in the tandem solar cell module of the series-connected 3T tandem solar cells, the third electrode may not be accessible from outside the interconnect layer or the module and thus does not form the third terminal.
[0033] Similarly, the first electrode of the first tandem solar cell may form the first terminal and the second electrode of the first tandem solar cell may form the second terminal, so that the tandem solar cell module always comprises three terminals (3T).
[0034] The 3T tandem solar cell can be formed monolithically, i.e. the first and second solar cells and the connection layer are made in one piece.
[0035] According to one embodiment of the invention, the embedding agent comprises ethylene vinyl acetate (EVA, CAS-NO: 24937-78-8) or a polyolefin elastomer (POE), wherein the embedding agent also imparts mechanical stability to the tandem solar cell.
[0036] According to another embodiment of the invention, the first absorber layer comprises a first perovskite layer or a first chalcopyrite absorber layer, in particular a CIGS layer, and / or wherein the second absorber layer comprises a second chalcopyrite absorber layer, in particular a CIGS layer, or a second perovskite layer.
[0037] The first absorber layer can in particular have a higher band gap than the second absorber layer.
[0038] Alternatively, the first or second absorber layer is or comprises amorphous or crystalline silicon.
[0039] In the context of this patent, the term "perovskite" refers in particular to a molecular structure with the general molecular formula ABX3, which is crystallized in the structure of the mineral perovskite and which, for example, has methylammonium (MA), cesium (Cs), and / or formamidinium (FA) as component A, while component B is often lead (Pb). X represents, for example, iodine (I), bromine (Br), and / or chlorine (Cl), or a mixture of these elements.
[0040] The first or second absorber layer comprising perovskite may have the molecular formula CSO,O5(FAO,83MA0,17)0,95Pb(Io,83Bro,17)3. Variations in the relative proportions of the components may also provide a functional absorber layer.
[0041] It should be noted that the absorber layer - such as chalcopyrite, CIGS or perovskite - may further comprise a plurality of layers of different materials and compounds applied to an absorber material so that the solar cell generates charge carriers.
[0042] For example, in the case that the second, ie the lower solar cell comprises chalcopyrite, e.g. CIGS, in the second absorber layer, additional layers comprising the second absorber layer may be e.g. CdS, i-ZnO and / or ZnO:Al.
[0043] In the case that the first, ie the topmost solar cell comprises perovskite in the first absorber layer, the additional layers in the first absorber layer may comprise one or more of, for example, NiO x, PTAA, C>>o, SnCE, IZO (indium zinc oxide), LiF. These additional layers can contribute to improved charge carrier extraction and conduction and / or prevent the so-called "shunting" of the solar cells of the tandem solar cell. For this purpose, for example, a NiO x -Underlayer is applied to the first solar cell.
[0044] All absorber layers can be designed as thin films.
[0045] According to another embodiment of the invention, the first absorber layer may comprise a self-assembled monolayer (SAM) as a hole-conducting layer, wherein the SAM comprises, for example, 2PACz (CAS No: 20999-38-6) and / or MeO-2PACz (Cas No: 2377770-18-6).
[0046] The absorbers in the solar cells comprised of the 3T tandem solar cell can, for example, be formed by a combination of perovskite as the first absorber layer and CIGS as the second absorber layer.
[0047] Another possible combination is chalcopyrite, such as CIGS, as the first absorber layer and perovskite as the second absorber layer.
[0048] The combination of absorber layers in the tandem solar cell is also possible as chalcopyrite, such as CIGS, as the first and second absorber layer or perovskite as the first and second absorber layer.
[0049] The at least one integral conduction element contacts the first transparent conductive layer and the second transparent conductive layer at a plurality of contact points with both conductive layers, wherein an electric current of charge carriers in the at least one integral conduction element, which is generated by the first absorber layer and the second absorber layer, can flow or flows in the direction of the third electrode without returning to the first or second transparent conductive layer, in particular such that a cumulative contact resistance of the tandem solar cell is reduced or minimized.
[0050] In the prior art (Talysa R Klein et al 2021), in which the interconnect layer comprises a plurality of silver-coated spheres, the charge carriers cannot flow towards a third electrode in the spheres without migrating back and forth along the contacts formed by the spheres with the conductive layers, which results in it having a comparatively higher resistance and ohmic losses.
[0051] According to another embodiment of the invention, the at least one one-piece conducting element extends in a plane of the connecting layer which extends substantially parallel to a surface of the at least one tandem solar cell facing the incident light.
[0052] The term "parallel" in the context of a layer refers specifically to local parallelism, since the layers of a tandem solar cell can exhibit a comparatively rough surface and layer structure when viewed microscopically. For this reason, the term "parallel" should be interpreted broadly.
[0053] According to another embodiment of the invention, the at least one one-piece conductive element extends within the connecting layer, in particular such that the at least one conductive element contacts the first and the second transparent conductive layer several times and thereby forms the plurality of contact points.
[0054] Therefore, the at least one integral conductive element can extend in a meandering manner within the connecting layer, in particular such that a plurality (multiple, n > 2) of contact points are formed. This embodiment enables fail-safe contacting of the first and second transparent conductive layers due to the redundancy provided by a plurality of contact points.
[0055] According to another embodiment of the invention, in regions within the first solar cell in which the first absorber layer is neither connected to the first conductive layer nor contacted by the first electrode, a first electrically insulating layer is arranged around the first absorber layer, so that in these regions the first absorber layer is electrically insulated from the connection layer, and / or in regions within the second solar cell in which the second absorber layer is neither connected to the second conductive layer nor contacted by the second electrode, a second electrically insulating layer is arranged around the second absorber layer, so that in these regions the second absorber layer is electrically insulated from the connection layer.This embodiment enables complete electrical isolation of the first and / or second absorber layer from the connection layer, thus minimizing the risk of a short circuit between the components of the tandem solar cell.
[0056] The first and / or second insulating layer may comprise intrinsic materials such as silicon oxide (SiO x ) or undoped ZnO.
[0057] According to another embodiment of the invention, the first insulating layer is configured such that the first electrode is electrically insulated from the at least one integral conducting element and / or wherein the second insulating layer is configured such that the second electrode is electrically insulated from the at least one conducting element.
[0058] In particular, in the tandem solar cell, the first and / or second insulating layer is configured such that at least one contacting region remains free for a third electrode from another tandem solar cell, in particular such that this third electrode can be contacted with the first and / or second electrode of the tandem solar cell. In this way, a series connection between two tandem solar cells can be created.
[0059] The 3T tandem solar cell is also embodied with a transparent upper protective layer, also referred to by those skilled in the art as a superstrate, which is arranged on the first solar cell, wherein the upper protective layer faces the incident light during operation or is configured to face it, and wherein the at least one tandem solar cell further comprises a lower substrate arranged on the second solar cell, wherein the lower substrate faces away from the incident light during operation or is configured to face away from it.
[0060] The upper and lower substrates can each be designed as a flexible layer so that the tandem solar cell or a corresponding tandem solar cell module can or is adapted to a curved or flexible surface.
[0061] For this purpose, the first and second substrates may comprise a transparent polymer layer. However, the upper and lower substrates may also be inflexible, forming a rigid tandem solar cell or a rigid tandem solar cell module.
[0062] For this purpose, the upper and lower substrates may comprise glass.
[0063] According to a second aspect of the invention, at least a first and a second 3T tandem solar cell form a tandem solar cell module, wherein the at least one first and the second tandem solar cell are electrically connected in series and wherein the electrode formed or connected to the at least one integral conducting element in the connecting layer of the first tandem solar cell is electrically connected to the first and / or the second electrode of the second tandem solar cell.
[0064] In particular, the tandem solar cell module according to the invention can be manufactured monolithically, ie the first and the second tandem solar cell are formed monolithically in one process each.
[0065] The tandem solar cell module according to this second aspect of the invention teaches an improved way of connecting the two tandem solar cells in series by exploiting the comparatively low complexity of the connecting layer with the at least one integral conducting element.
[0066] While the at least first and second 3T tandem solar cells each comprise at least one separate integral conduction element, the third electrode of the first 3T tandem solar cell contacts the second tandem solar cell, thus creating a series circuit.
[0067] In particular, the at least one integral conductive element of the at least first 3T tandem solar cell and the at least one integral conductive element of the at least second 3T tandem solar cell are not directly electrically connected to one another. In particular, the conductive elements are insulated from one another by the electrically insulating embedding medium.
[0068] According to one embodiment, the third electrode of the first 3T tandem solar cell and the at least one integral conduction element of the second 3T tandem solar cell are electrically insulated from one another, wherein the at least one conduction element and the third electrode are insulated by the embedding agent of the connection layer of the first and / or second 3T tandem solar cell, so that a charge carrier current cannot flow directly from the third electrode of the first 3T tandem solar cell to the at least one conduction element of the second 3T tandem solar cell.
[0069] This embodiment enables a series connection of at least two 3T tandem solar cells, which are formed in one piece - monolithic.
[0070] In the monolithic embodiment of a 3T tandem solar cell module according to the invention, the first electrodes of the at least first and second 3T tandem solar cells are electrically insulated from one another by means of a first insulating cut which is arranged between the first electrodes such that the first absorber layer of the first 3T tandem solar cell is electrically insulated from the first absorber layer of the second 3T tandem solar cell, and wherein the second electrodes of the first and second 3T tandem solar cells are electrically insulated from one another by means of a second insulating cut which is arranged between the second electrodes such that the second absorber layer of the first 3T tandem solar cell is electrically insulated from the second absorber layer of the second 3T tandem solar cell.
[0071] In particular, the first and / or the second electrode are physically separated from each other at the first and / or the second insulating cut, ie by means of a groove produced by a mechanical tool or an optical scribing, such as by laser ablation.
[0072] An insulating cut, also referred to as a separating joint, is designed in the sense of the invention in such a way that the layers separated by it, in particular the electrodes, are electrically insulated from one another.
[0073] This design enables the production of a large number of 3T tandem solar cells, for example, fabricated on integral substrates and layers, and which are suitably electrically insulated so that the large number can be produced relatively easily despite being formed in integral substrates and layers.
[0074] According to another embodiment of the invention, the first electrodes of the at least first and second 3T tandem solar cells are integrated into a solar cell module, e.g. formed as a first electrode substrate and separated by means of a mechanical scribing or a laser ablation process, whereby the first insulating cut is produced and in particular the at least two first electrodes are formed, and wherein the second electrodes of the at least first and second 3T tandem solar cells are integrated, e.g. formed as a second electrode substrate and separated by means of a mechanical scribing or a laser ablation process, whereby the second insulating cut is produced and in particular the second electrodes of the at least two 3T tandem solar cells are formed.
[0075] This embodiment specifies the advantages and possible manufacturing options with respect to one-piece electrode substrates.
[0076] According to an alternative embodiment of the invention, the tandem solar cell module comprises at least a first and a second 3T tandem solar cell electrically connected in parallel.
[0077] According to a third aspect of the invention, a method for producing a tandem solar cell module comprising at least two 3T tandem solar cells according to the invention is disclosed, the method essentially comprising the following steps: a) producing a plurality of first, i.e. upper, solar cells on a superstrate; b) producing a plurality of second, i.e. lower, solar cells on a substrate; c) connecting the first and second solar cells via a connecting layer, the connecting layer comprising an electrically insulating embedding agent and at least one integral conducting element for each pair of first and second solar cells of a 3T tandem solar cell, each conducting element being designed and arranged such that it forms a third electrode or is electrically contacted with such a third electrode.
[0078] Detailed steps of manufacturing are disclosed below.
[0079] It is emphasized that the upper and lower solar cells are manufactured individually and separately, e.g., by using a substrate process for the second (lower) solar cells, which may comprise GIGS, for example, and a superstrate process for the first (upper) solar cells, which may comprise perovskite, for example. Once the upper and lower solar cells are formed, the solar cells are assembled in a sandwich structure, which offers advantages over tandem solar modules, which are formed layer by layer in a monolithic process.
[0080] The steps comprised by the method in detail are the following: i) cutting a first electrode substrate to form the first electrodes of the at least first and second 3T tandem solar cell, thereby forming at least one first insulating cut between the first electrodes; ii) cutting a second electrode substrate to form the second electrodes of the at least first and second 3T tandem solar cell, thereby forming at least one second insulating cut between the second electrodes; iii) producing, e.g. by applying or growing, a first absorber layer of the at least first and second 3T tandem solar cell in one piece on the first electrodes, whereby the first insulating cut can be filled with the material of the first absorber layer;iv) producing, e.g. by applying or growing, a second absorber layer of the at least first and second 3T tandem solar cell in one piece on the second electrodes, whereby the second insulating cut can be filled by the material of the second absorber layer; v) producing a first transparent conductive layer in one piece on the first absorber layer; vi) producing a second transparent conductive layer in one piece on the second absorber layer; vii) cutting the one-piece first absorber layer and the one-piece first transparent conductive layer by means of a mechanical scribing or a laser ablation process, so that at least two first solar cells are produced; viii) cutting the one-piece second absorber layer and the one-piece second transparent conductive layer by means of a mechanical scribing or a laser ablation process, so that at least two second solar cells are produced;ix) arranging and aligning at least a first integral conducting element and a separate at least second conducting element, and embedding the conducting elements with an embedding agent between the first and the second solar cells, so that the solar cells are arranged one above the other and so that the at least first integral conducting element can form a plurality of contact points with each of the first and second transparent conductive layers of a first 3T tandem solar cell and so that the at least second integral conducting element can form a plurality of contact points with each of the first and second transparent conductive layers of the second 3T tandem solar cell;x) heating the connecting layers of encapsulant and conducting elements so that the encapsulant is adhesively bonded to the first and second solar cells and so that the at least first and at least second integral conducting elements form a plurality of contacts with the first and second transparent conductive layers, respectively;
[0081] It should be noted that, particularly in steps iii) and iv), the insulating sections are not given any electrical conductivity by the -potential- filling with the material of the absorber layers.
[0082] It should also be noted that the term "the first solar cell" is used synonymously with "the upper solar cell." Likewise, the term "the second solar cell" is used synonymously with "the lower tandem solar cell." The adjectives "upper" and "lower" refer to the light incidence, with the side of light incidence being the upper side.
[0083] The method for producing the tandem solar cell module enables rapid and large-scale production, wherein the module comprises two or more 3T tandem solar cells connected in series, which according to the invention have three terminals.
[0084] In particular, the upper and lower solar cells are manufactured individually and separately, e.g., by applying a substrate process for the second (lower) solar cells, e.g., comprising CIGS, and a superstrate process for the first (upper) solar cells, e.g., comprising perovskite. Once the upper and lower solar cells are formed, the solar cells are joined together by the interconnect layer in a sandwich construction and contacted by the integral conductive elements. For cutting the insulating cut that separates the electrodes, a scribing method, such as that commonly used for PI structuring, can be used.
[0085] According to another embodiment, the at least first and at least second one-piece conducting elements comprise a third electrode by being connected to such a third electrode or forming it integrally, wherein the third electrode of a first 3T tandem solar cell forms electrical contact with the first and / or the second electrode of a second tandem solar cell in a separation cut between the first absorber layers and the second absorber layers, in particular in the case that the third electrode is not the last of a row of tandem solar cells, i.e. is not the third connection electrode. A separation cut separates the 3T tandem solar cells from one another in a tandem solar cell module, so that they are present in the module as individual 3T tandem solar cells, which are nevertheless interconnected to form the module.The separation cuts typically extend from the upper electrode, without encompassing it, to the lower electrode, without encompassing it. These latter separation cuts can be formed during process steps vii) and viii).
[0086] The third electrode may comprise a busbar or an electrically conductive element to which the at least one integral conducting element is connected.
[0087] Similarly, the third terminal electrode may comprise or be a busbar to which the at least one integral conducting element is connected.
[0088] According to another embodiment of the invention, after step viii), a first and a second insulating layer are produced, e.g., by a printing or other deposition process, in particular after the conductive layers and the exposed electrode regions have been masked by a protective mask material.
[0089] Example
[0090] An exemplary embodiment is described below in conjunction with two figures. Fig. 1: Schematic cross-sectional view of a tandem solar cell module with two series-connected 3T tandem solar cells according to the invention.
[0091] Fig. 2: Detail from Fig. 1
[0092] Fig. 1 shows a schematic cross-sectional view of a tandem solar cell module comprising a first and a second 3T tandem solar cell 10, 10' connected in series. The first and second 3T tandem solar cells 10, 10' each comprise two solar cells 11, 11', 12, 12' arranged one above the other (tandem arrangement). The terms "one above the other," "top side," "bottom side," etc., refer in particular to a direction of the 3T tandem solar cells 10, 10' with respect to the incident light 100, e.g., sunlight. According to this term, the top side refers to a side facing the incident light 100 or at least closer to that side on which the incident light 100 strikes the 3T tandem solar cell or module when they are set up and aligned for operation.
[0093] Similarly, the term "bottom" refers to the side facing away from the light. Consequently, the term "on top" or similar terms refer to the direction, also called the z-axis, from the bottom to the top of the 3T tandem solar cell 10, 10', or module 1.
[0094] The 3T tandem solar cells 10, 10' and the tandem solar cell modules 1 comprise a first extension direction (z-axis) extending from the lower to the upper side.
[0095] Along this extension direction, the layers and electrodes 11-1, 11'-1, 12-1, 12'-1 of the 3T tandem solar cells 10, 10' are planar, parallel to the plane formed by the x- and y-axes orthogonal to the extension direction.
[0096] Fig. 1 shows a cross-section along the x- and z-axes. The illustration is not to scale and serves only as an orientation for the general arrangement of the individual components of the 3T tandem solar cells 10, 10', or the tandem solar cell module 1.
[0097] Along the y-axis, the cross-section can simply be extruded orthogonally to the xz-plane to obtain the 3D structure of the tandem solar cell module 1 / the 3T tandem solar cells 10, 10'. However, it should be noted that the x-, y-, and z-axes can only provide a local coordinate system, which can vary in orientation if the tandem solar cell module is configured curved.
[0098] The general sequence of layers in the tandem solar cell module 1 in the embodiment can be summarized as follows, starting from the top side:
[0099] (optional) a transparent protective layer 18 a first solar cell 11, 11', which comprises at least the following: a) first transparent electrode 11-1, 11'-1, b) a first absorber layer 11-2, 11'-2, c) a first transparent conductive layer 11-3, 11'-3, a connecting layer 13, which comprises at least one electrically conductive one-piece line element 13-3, 13'-3 for each tandem solar cell 10, 10' of the module 1, which is embedded in an embedding agent 13-2; a second solar cell 12, 12', comprising at least the following: a) a second transparent conductive layer 12-3, 12'-3, b) a second absorber layer 12-2, 12'-2, c) a second electrode 12-1, 2'-1, and a lower substrate 19. the transparent protective layer 18 may be made of glass or a flexible transparent layer, such as a polymer.The term “transparent” refers in particular to the property of the material to be permeable to electromagnetic radiation in the wavelength ranges in which the first and second absorber layers absorb the radiation and convert the radiation into the charge carriers of the respective solar cell.
[0100] For this purpose, the first electrode 11-1, 11'-1 can be made of indium zinc oxide (IZO) or indium tin oxide (ITO) or another transparent and electrically conductive material. The first absorber layer 11-2, 11'-2 can comprise a plurality of different layers forming the absorber layer 11-2, 11'-2. Typical compositions, layers, and layer sequences are known and not of specific importance to the invention. For example, the first absorber layer 11-2, 11'-2 can comprise a CIGS or a perovskite layer.
[0101] The first transparent conductive layer 11-3, 11-3 essentially forms an electrode of the first solar cell 11, 11'. The first transparent conductive layer 11-3, 11-3 may comprise or consist of ZnO:Al and may generally comprise a transparent conductive oxide (TCO).
[0102] Similarly, the second transparent conductive layer 12-3, 12'-3 forms an electrode of the second solar cell 12, 12'. The second transparent conductive layer 12-3, 12'-3 may comprise or consist of ZnO:Al and may generally comprise a transparent conductive oxide (TCO).
[0103] For contacting the first and the second solar cell 11, 11', 12, 12', the connecting layer 13 in each 3 T tandem solar cell comprises a one-piece conducting element 13-3, 13'-3, in particular a wire, which electrically contacts the first and the second solar cell 11, 12, 11', 12 by forming a plurality of contact points K1, K2, K3, K4, K5 on each of the transparent conducting layers 11-3, 11-3, 12-3, 12'-3. For clarity, Fig. 2 shows a section of the tandem solar cell module of Fig. 1 (a tandem solar cell 10), illustrating, by way of example, the contact points K1, K2, K3, K4, K5 of the at least one integral conduction element 13-3, 13'-3 of the at least one integral conduction element 13-3 of this tandem solar cell. This inventive type of contacting enables the charge carriers generated by the first and second solar cells 11, 11', 12, 12' to be conducted to the third electrode 13-1, 13'-1.In particular, the conduction element 13-2, 13'-2 contacts the transparent conductive layer 11-3, 11-3, 12-3, 12'-3 at a plurality of contact points K1, K2, K3, K4, K5, respectively. In the example shown, a first and second 3T tandem solar cell 10, 10' are electrically connected in series. Therefore, the third electrode 13-1 of the first 3T tandem solar cell 10 contacts the first and second electrodes 11'-1, 12'-1 of the second 3T tandem solar cell 10', wherein the third electrode 13'-1 of the second tandem solar cell 10' forms a terminal electrode, i.e., the third terminal 13'-1. Alternatively, the one-piece conductive element 13-2, 13'-2 can continuously contact the first and second solar cells 11, 12, 11', 12, so that essentially only one contact section is formed. (This embodiment is not shown.)
[0104] The tandem solar cell module 1 also provides a first and a second terminal, namely at the first and second electrodes of the first tandem solar cell or at a conductive connection attached thereto (not shown).
[0105] Of course, this concept of interconnecting 3T tandem solar cells according to the invention can extend to three or more 3T tandem solar cells 10, 10' connected in series, as long as the first tandem solar cell 10 provides the first and second terminals 13-4, 13-5 and the third electrode 13'-1 of the last 3T tandem solar cell in series forms the third terminal 13'-1. Furthermore, every third electrode 13-1, 13'-1 (except for the last one in the series) of a 3T tandem solar cell 10, 10' of such a tandem solar cell module 1 contacts the first and / or second electrode of a subsequent tandem solar cell connected in series in the module 1.
[0106] It is important that the integral conducting elements 13-3, 13 '-3 in the first and second 3T tandem solar cells 10, 10' and more generally of all 3T tandem solar cells 10, 10' of such a module 1 are not in direct electrical contact with each other, so that the conducting elements 13-3, 13 '-3 are electrically bonded by an embedding agent which is
[0107] Connection layer 13 is included, can be isolated from each other. This allows the charge carriers to move along the intended path (— OO— >) through the tandem solar cell module and prevents a short circuit.
[0108] The one-piece conduction element 13-3, 13'-3 may be formed as a wire, wherein the third electrode 13-1, 13'-1 of each or the last (e.g., second) 3T tandem solar cell 10, 10' is formed as a busbar to which the conduction element 13-3, 13'-3, e.g., the wire, is connected.
[0109] The busbar is connected to either the first and / or second electrode 11-2, 11'-2, 12-2, 12'-2 of the respective subsequent 3T tandem solar cell 10, 10', with the busbar of the last tandem solar cell 10' at least partially forming the third terminal (electrode) 13'-1. The connecting layer 13 comprises an embedding agent 13-2, which is electrically insulating and firmly connects the two solar cells 11, 11', 12, 12' of each 3T tandem solar cell 10, 10'. The assembled tandem solar cell module 1 is thus formed in one piece or monolithically.
[0110] The joining of the first and second solar cells 11, 11', 12, 12' is achieved in particular by heating the connecting layer 13 with the embedding agent 13-2 and the integral conductive element 13-3, 13'-3, so that it acts like an insulating adhesive. In the connecting layer 13, the conductive element 13-3, 13'-3 meanders, for example, between the first and second transparent conductive layers 11-3, 11'-3, 12-3, 12'-3, thus forming the contact points K1, K2, K3, K4, K5.
[0111] Each integral conductive element 13 of each 3T tandem solar cell 10, 10' is electrically insulated from each other.
[0112] The first electrodes 11-1, 11'-1 and the second electrodes 12-1, 12'-1 of the tandem solar cell module 1 are each electrically separated by an insulating cut 16, 17 (corresponding to a PI structure) between the first electrode 11-1, 11'-1 and the second electrode 12-1, 12'-1, respectively. These non-conductive insulating cuts 16, 17 can be formed by mechanical scribing or an optical process, such as laser ablation. The insulating cuts 16, 17 are arranged before, upstream of, or above the contacting sections of the third electrode 13-1, 13'-1 with the first and / or second electrode 13-1, 12'-1 of the second tandem solar cell 10'. In this way, the solar cells 11, 1T, 12, 12' and the 3T tandem solar cells 10, 10' are connected in series in a tandem solar cell module.
[0113] In order to prevent a short circuit, the first and second absorber layers 11-2, 11'-2, 12-2, 12'-2 of each tandem solar cell 10, 10' in a tandem solar cell module can be covered by a first insulating layer 14, 14' arranged around the first absorber layers 11-2, 11'-2, and a second insulating layer 15, 15' arranged around the second absorber layer 12-2, 12'-2, so that the absorber layers 11-2, 11'-2, 12-2, 12'-2 are in contact with the first, second or third electrode 11-1, 11'-1, 12-1, 12'-1, 13-1, 13'-1 and with the integral conduction element 13-3, 13'-3 are electrically insulated. These insulating layers 14, 14', 15, 15' thus provide a means of manufacturing the tandem solar cell module without short circuits.These regions are located or extend, for example, along the z-direction of the absorber layers 11-2, 11-2, 12-2, 12'-2 and the sections of the first absorber layers 11-2, 11-2 that face away from the top side of the tandem solar cell 10, 10' and that are not covered by the transparent conductive layer 11-3, 11-3.
[0114] Similarly, these regions may be arranged further away or extend along the portions of the second absorber layers 12-2, 12'-2 that face the top side of the tandem solar cell 10, 10' and that are not covered by the transparent conductive layer 12-3, 12'-3.
[0115] A first electrically insulating layer 14, 14' is arranged around the first absorber layer 11-2, 11T-2, so that in these regions the first absorber layer 11-2, 11T-2 is electrically insulated from the connecting layer 13, and / or wherein in regions inside the second solar cell 12, 12' in which the second absorber layer 12-2, 12'-2 is neither connected to or contacted by the second conductive layer 12-3, 12'-3 nor connected to or contacted by the second connection electrode 13'-1, a second electrically insulating layer 15, 15' is arranged around the second absorber layer 12-2, 12'-2, so that in these regions the second absorber layer 12-2, 12'-2 is electrically insulated from the connecting layer 13.
[0116] The absorber layers 11-2, 11'-2, 12-2, 12'-2 and the transparent, conductive layers 11-3, 11'-3, 12-3, 12'-3 are each separated from each other by a separation cut, forming the individual 3T tandem solar cells. The separation cut is not shown for reasons of clarity, but is clearly identifiable by its location and function. The separation cut is to be made using a mechanical scribing or laser ablation process.
[0117] This embodiment enables complete electrical insulation of the first and / or second absorber layer 11-2, 11'-2, 12-2, 12'-2 from the connecting layer 13, so that the risk of a short circuit between the components of the tandem solar cell 10, 10' is minimized.
Claims
Patent claims 1. 3T tandem solar cell (10, 10'), comprising at least: a first solar cell (11, 11'), comprising at least a first absorber layer (11-2, 11'-2) arranged between a first electrode (11-1, 11'-1) on one side of the first solar cell (11, 11') facing the incident light (100) and a first transparent conductive layer (11-3, 11'-3) on one side of the first solar cell (11, 11') facing away from the incident light (100); a second solar cell (12, 12'), comprising at least a second absorber layer (12-2, 12'-2) arranged between a second electrode (12-1, 12'-1) on one side of the second solar cell (12, 12') facing away from the incident light (100) (100) is turned away, and a second transparent conductive layer (12-3, 12'-3) is provided on one side of the second solar cell which is turned towards the incident light (100);a connecting layer (13) arranged between the first and the second solar cell (11, 11', 12, 12'), wherein the; The interconnection layer (13) forms an electrically conductive connection between the first and the second solar cell (11, 11', 12, 12'); characterized in that the interconnection layer (13) comprises at least one electrically conductive, one-piece conductor element (13-3, 13'-3), and wherein the at least one one-piece conductor element (13-3, 13'-3) is embedded in an embedding means (13-2) while maintaining contact points (K1, K2, K3, K4, K5) to the first and to the second transparent, conductive layer (11-3, 11'-3, 12-3, 12'-3) respectively, and the at least one one-piece conductor element (13-3, 13'-3) is connected to or forms a third electrode (13-1, 13'-1).
2. 3T tandem solar cell (1) according to claim 1, wherein the embedding agent comprises ethylene vinyl acetate (EVA) or a poly olefin elastomer (POE). 3T tandem solar cell according to claim 1 or 2, wherein the first absorber layer (11-2, 11'-2) comprises a first thin-film material layer such as a first perovskite layer or a first chalcopyrite absorber layer, and / or wherein the second absorber layer (12-2, 12'-2) comprises a second thin-film material layer such as a second chalcopyrite absorber layer or a second perovskite layer. 3T tandem solar cell (1) according to one of the preceding claims, wherein the at least one one-piece conduction element (13-3, 13'-3) contacts the first and the second transparent conductive layer (11-3, 11'-3, 12-3, 12'-3) at several contact points (K1, K2, K3, K4, K5), wherein an electric current of charge carriers can flow in the at least one one-piece conduction element (13-3, 13'-3) to the third electrode (13-1, 13'-1), in particular without to the first or second transparent conductive layer (11-3, 11'-3, 12-3, 12'-3) of the at least one tandem solar cell (10,to return to the 3T tandem solar cell (1) according to one of the preceding claims, wherein the at least one one-piece conductor element (13-3, 13'-3) extends in a plane of the interconnection layer (13) which extends substantially parallel to a surface of the at least one tandem solar cell (10, 10') which faces the incident light (100). 3T tandem solar cell (1) according to one of the preceding claims, wherein in regions within the first solar cell (11, 11') where the first absorber layer (11-2, 11'-2) is not connected to the first conductive layer (11-3, 11'-3) or to the first electrode (11-1, 11'-1), a first electrically insulating layer (14, 14') is arranged around the first absorber layer (11-2, 11'-2) such that in these regions the first absorber layer (11-2, 11'-2) is electrically insulated from the connecting layer (13), and / or wherein in regions within the second solar cell (12, 12'),in which the second absorber layer (12-2, 12'-2) is not connected to either the second conductive layer (12-3, 12'-3) or the second electrode (12-1, 12'-1), a second electrically insulating layer (15, 15') is arranged around the second absorber layer (12-2, 12'-2) so that in these areas the second absorber layer (12-2, 12'-2) is electrically isolated from the connecting layer (13). 3T tandem solar cell (1) according to claim 6, wherein the first insulating layer (14, 14') is arranged such that the first electrode (11-1, 11'-1) is electrically insulated from the at least one one-piece conducting element (13-3, 13'-3) and / or wherein the second insulating layer (15, 15') is arranged such that the second electrode (12-1, 12'-1) is electrically insulated from the one-piece conducting element (13-3, 13'-3). Tandem solar cell module (1) comprising at least two 3T tandem solar cells according to one of the preceding claims, wherein the first and the second tandem solar cell (10, 10') are electrically connected in series and wherein the third electrode (13-1) of the first tandem solar cell (10) is electrically connected to the first and / or the second electrode (11'-1, 12'-1) of the second tandem solar cell (10').Tandem solar cell module (1) according to claim 8, wherein the third electrode (13-1) of the first tandem solar cell (10) and the at least one one-piece conductor element (13'-3) of the second tandem solar cell (10') are electrically insulated from each other, so that a charge carrier current cannot flow directly from the third electrode (13-1) of the first tandem solar cell (10) to the at least one conductor element (13'-3) of the second tandem solar cell (10').Tandem solar cell module (1) according to claim 8 or 9, wherein the first electrodes (11-1, l l'-l) of the first and the second tandem solar cell (10, 10') are electrically isolated from each other by means of a first insulating section (16) which is configured such that the first absorber layer (11-2) of the first tandem solar cell (10) is electrically isolated from the first absorber layer (11'-2) of the second tandem solar cell, and wherein the second electrodes (12-1, 12'- 1) of the first and the second tandem solar cell (10, 10') are electrically isolated from each other by means of a second insulating section (17) which is configured such that the second absorber layer (12-2) of the first tandem solar cell (10) is electrically isolated from the second absorber layer (12'-2) of the second tandem solar cell (10'). Tandem solar cell module (1) according to claim 10, wherein the first electrodes (11-1, l l'-l) of the first and the second tandem solar cell are of one piece. (as a first electrode substrate) and have been formed and separated by a mechanical scribing or laser ablation process, thereby producing the first insulating cut (16), and wherein the second electrodes (12-1, 12'-1) of the first and second 3T tandem solar cell have been formed as an integrated component and separated by a mechanical scribing or laser ablation process, thereby producing the second insulating cut (17). Method for manufacturing a tandem solar cell module (1) according to any one of claims 8 to 11, comprising the following steps: i) Cutting a first electrode substrate to separate the first electrodes (11-1, 1 l'-l) to form the first and second tandem solar cell (10, 10'), thereby forming the first insulating cut (16) between the first electrodes (11-1, 1 l'-l); ii) cutting a second electrode substrate to form the second electrodes (12-1, 12'- 1) of the first and second tandem solar cell (10, 10'), thereby forming the second insulating cut (17) between the second electrodes (12-1, 12'- 1); iii) generating the first absorber layer (11-2, 11'-2) of the first and second tandem solar cell (10, 10') on the first electrodes (11-1, 1 l'-l) in one piece; iv) Producing the second absorber layer (12-2, 12'-2) of the at least first and second tandem solar cell (10, 10') on the second electrodes (12-1, 12'-1) in one piece; v) Producing the first transparent conductive layer (11-3, 11'-3) in one piece on the first absorber layer (11-2, 11'-2);vi) Creating the second transparent conductive layer in one piece on the second absorber layer (12-2, 12'-2); vii) Cutting the one-piece first absorber layer and the one-piece first transparent conductive layer of the first and second 3T tandem solar cell (10, 10') by means of a mechanical scribing or laser ablation process, so that the first absorber layers (11-2, 11'-2); and the first transparent conductive layers (11-3, 11'-3) of the first and second tandem solar cells (10, 10') are produced in the shape of the first solar cells (11, 11'); viii) cutting the one-piece second absorber layer and the one-piece second transparent conductive layer of the first and second 3T tandem solar cells (10, 10') by means of a mechanical or laser ablation process, so that the second absorber layers (12-2, 12'-2) and the second transparent conductive layers (12-3, 12'-3) of the first and second tandem solar cells (10, 10') are produced in the shape of the second solar cells (12, 12');ix) Arranging and aligning the interconnect layer (13, 13'), which comprises at least one one-piece conductor element and the embedding means (13-2), between the first and the second solar cell (11, 11', 12, 12'), such that the first and the second solar cell (11, 11', 12, 12') are superimposed and such that the at least one one-piece conductor element forms several contact points (K1, K2, K3, K4, K5) with each of the first and second transparent conductive layer (11-3, 12-3); x) Heating the bonding layer (13) so that the embedding medium (13-2) is adhesively bonded to the first and second solar cells (11, 11', 12, 12') and so that the at least one one-piece conducting element (13-3, 13'-3) forms several contact points (K1, K2, K3, K4, K5) with each of the first and second transparent conductive layers (11-3, 11'-3, 12-3, 12'-3). A method according to claim 12, wherein the at least one one-piece conductor element (13-3, 13'-3) is connected to or integrally forms the third electrode (13-1, 13'-1), wherein, upon heating, the third electrode (13-1) of the first tandem solar cell (10) is electrically contacted with the first and / or the second electrode (11'-1, 12'-1) of the second tandem solar cell (10'). A method according to claim 12 or 13, wherein, after step viii), the first and the second insulating layer (14, 14', 15, 15') are produced. 28 CORRECTED SHEET (RULE 91) ISA / EP