PN Junction Thermoelectric Module

Abstract

pn junction thermoelectric module. Thermoelectric module (10), comprising a substrate (20), at least two adjacent thermoelectric elements (11, 12) made of two materials doped with different types of doping extending over the substrate and electrically connected to each other on the side of the substrate (20) and / or opposite the substrate (20) by a mixture electrical junction formed by a layer of a mixture of the two materials doped with different types of doping composing the two thermoelectric elements (11, 12). Figure for the abbreviation: Fig. 1

Description

Title of the invention: PN junction thermoelectric module technical field

[0001] The present invention relates to a thermoelectric module. Previous technique

[0002] Thermoelectric modules are generally made of p-type and n-type doped materials and comprise pads arranged on a substrate. The pads are electrically connected in series by metallic junctions and thermally connected in parallel.

[0003] The electrical performance of a thermoelectric device in generator mode is given by: a. An internal electrical resistance Rint at the junction between p-type and n-type doped materials determined as follows:

[0004] Rint = N x pnp x H / A + Rc + Rmet

[0005] With N the number of junctions between the p-type and n-type doped materials of the structure, pnp is the charge density at the pn junctions, H the length of a line or pad, A the cross-section of a line or pad, Rc the total resistance of the contacts and Rmet the total resistance of the metallic junctions, a. A useful electrical power Pu = V2 / 4Rint.

[0006] To have a high useful electrical power, it is therefore necessary to have in particular a low electrical resistance Rint and therefore limit the contribution to the resistance of the total resistances of the contacts Rc and the total resistance of the metallic junctions.

[0007] The fabrication of thermoelectric modules is generally carried out in several stages: the fabrication of thermoelectric materials, notably by sintering, the shaping of the pads, their metallization, and their assembly with the substrate. The junctions between the different pads with varying doping are conventionally made by electrical connections in the form of ribbon or metallic deposits between the pads.

[0008] EP3985745 is known for a method of manufacturing a thermoelectric device. The method includes several steps, among which are the fabrication of comb-shaped parts, their mechanical and electrical assembly, followed by cutting to form the thermoelectric junctions.

[0009] FR3140994 relates to a method for manufacturing thermoelectric structures using additive manufacturing techniques such as laser powder bed fusion or selective laser sintering and may include a substrate removal step to obtain the final structure.

[0010] FR3140993 also describes a method for manufacturing thermoelectric structures using additive manufacturing techniques, preferably laser powder bed fusion or selective laser sintering. These manufacturing processes require assembly steps and do not allow for the fabrication of thermoelectric devices on complex-shaped surfaces.

[0011] The article J. Lee, S. Choo, H. Ju, J. Hong, SE Yang, F. Kim, DH Gu, J. Jang, G. Kim, S. Ahn, JE Lee, SY Kim, HG Chae, JS Son, Doping-Induced Viscoelasticity in PbTe Thermoelectric Inks for 3D Printing of Power-Generating Tubes. Adv. Energy Mater. 2021, 11, 2100190. describes thermoelectric modules manufactured by an additive manufacturing method, specifically solution printing, a 3D printing method. PbTe particles are synthesized, and colloidal inks are then produced from these particles. The inks are then extruded using a 3D printer, then dried and heat-treated. The resulting objects are then assembled to form thermoelectric modules.

[0012] The article Hue et al. ACS Applied Materials and Interfaces 2023, Vol 15 / Issue 32, 3D Printing of Bi2Te3-Based Thermoelectric Materials with High Performance and Shape Controllability also describes thermoelectric modules manufactured by an additive manufacturing method, in particular by selective laser melting, to obtain thermoelectric modules in the shape of half-rings.

[0013] In all these prior arts, the thermoelectric elements in the form of different doping pads are electrically connected to each other by metallic ribbon-type connections.

[0014] There is therefore a need to develop a new thermoelectric module with satisfactory thermoelectric performance, easy to manufacture and allowing great versatility of application and use. Description of the invention

[0015] The present invention meets this need by means of a thermoelectric module comprising, - a substrate, - at least two adjacent thermoelectric elements in two materials doped according to different types of doping extending over the substrate and electrically connected to each other on the side of the substrate and / or opposite the substrate by an electrical mixture junction formed by a layer of a mixture of the two materials doped according to different types of doping composing the two thermoelectric elements.

[0016] The invention also relates to a method for manufacturing a thermoelectric module as mentioned above.

[0017] Such a mixing electrical junction allows for a high-performance electrical connection between the two thermoelectric elements without the need for additional metallic connecting elements. This therefore simplifies module manufacturing and provides satisfactory thermoelectric performance.

[0018] Preferably the thermoelectric elements and the electrical mixing junction are formed by deposition under concentrated energy.

[0019] The use of a concentrated energy deposition method makes it possible to deposit materials onto a wide variety of substrate shapes, including cylindrical substrates, which is not possible or is complex with other additive manufacturing processes such as laser powder bed fusion. This allows modules to be built directly onto substrates adapted to the shape of the heat source, whether hot or cold, thus facilitating the manufacture of such modules and improving yields.

[0020] Thus, deposition under concentrated energy allows the manufacture of modules of complex shapes, such as cylindrical modules, which may be more suitable for certain heat sources to be dissipated.

[0021] Furthermore, the concentrated energy deposition technique can be performed with a plurality of nozzles emitting powder of the materials to be deposited towards the melting zone, as we will see later. The presence of multiple nozzles allows for the deposition of different materials using different nozzles. In particular, this makes it possible to form p-doped and n-doped thermoelectric elements without having to change the powder in the device, using different nozzles. This simplifies manufacturing and improves the accuracy of both the fabrication and the junction between the two materials. This can improve the energy performance of the thermoelectric module, notably by reducing electrical resistance at the junctions.

[0022] Concentrated energy deposition also allows for a wide variety of thermoelectric unit shapes. This enables greater versatility in the configuration and performance of thermoelectric modules, making it possible to manufacture a custom thermoelectric module based on the desired performance, shape, and available space. Certain thermoelectric element shapes, in particular, can improve the size of the thermoelectric elements within a module, allowing for better optimization of space within the thermoelectric module and thus improving module performance for the same footprint.

[0023] It is therefore possible, depending on the situation, in particular the specifications and the environment, to have varied modules whose shape and dimensions are adapted to each situation.

[0024] Concentrated energy deposition also allows for great versatility in the electrical configuration between the thermoelectric elements, in particular connecting the thermoelectric elements in series or in parallel to adapt the performance. Electrical junction

[0025] The module may include a thermoelectric circuit comprising a plurality of adjacent thermoelectric elements electrically connected to each other by electrical junctions, at least one of which is a mixing junction, the interconnected thermoelectric elements being made of different doped materials. Preferably, all electrical junctions on the substrate side and / or the side opposite the substrate are mixing junctions. In one embodiment, all electrical junctions are mixing junctions. Alternatively, all electrical junctions on one side of the substrate and the side opposite the substrate are mixing junctions, and all electrical junctions on the other side of the substrate and the side opposite the substrate are formed by metallic junctions, in particular metallic strips.

[0026] The electrical mixing junction(s) may extend between two lateral surfaces of the opposing thermoelectric elements.

[0027] The surface of the electrical mixing junction along a median plane to the two thermoelectric elements connected to each other by said electrical mixing junction may have an area greater than or equal to 50%, or better, greater than or equal to 70%, of the area of ​​a cross-section of a thermoelectric element. Thermoelectric elements

[0028] Preferably, the adjacent thermoelectric elements connected by a mixing electrical junction have substantially identical structures except for the doping. Preferably, the thermoelectric elements connected by a mixing electrical junction are made of identical materials doped differently. Preferably, all the thermoelectric elements are made of identical materials doped differently.

[0029] Alternatively, the thermoelectric elements connected by a mixing electrical junction are made of different thermoelectric materials doped differently. In this case, the electrical elements of the different doped thermoelectric materials can alternate along the thermoelectric circuit.

[0030] Preferably, the adjacent thermoelectric elements are connected to separate thermoelectric elements at their ends. In this case, the elements Thermoelectric elements are connected together in series. Thermoelectric elements can be electrically connected in series with each other only on one side of the substrate and on the opposite side of the substrate.

[0031] Alternatively, at least two thermoelectric elements can be electrically connected to each other on the substrate side and on the opposite side of the substrate. In this case, the circuit comprises elements electrically connected to each other in parallel.

[0032] At least one, better, the thermoelectric elements, can each be monolayer.

[0033] Alternatively, at least one, or better yet, the thermoelectric elements are multilayered. They can comprise several layers of different materials doped with the same type of doping. This can allow for broader mechanical properties, particularly thermal compatibility, by having a combination of thermoelectric materials adapted to different temperature ranges.

[0034] Preferably, the layers of different doped materials can be separated from each other by one or more interface structures.

[0035] The interface structure(s) may include at least one layer of a diffusion barrier material, in particular copper or nickel. Such interface materials limit diffusion between the two thermoelectric elements, ensure good electrical contact, particularly low resistance, and limit thermal expansion problems between the two thermoelectric elements.

[0036] The interface structure can be multilayered and comprise the layer in a material forming a diffusion barrier sandwiched between two layers in a thermoelectric material different from the thermoelectric materials it separates.

[0037] Preferably, in this case, the thermoelectric elements are identical.

[0038] Thermoelectric elements may be composed of one or more pads of the same doping. Preferably, the thermoelectric elements consist of a single pad. Alternatively, the thermoelectric elements consist of several pads, these being of the same doping and electrically connected both on the substrate side and on the side opposite the substrate, the pads then being connected in parallel with each other. Material

[0039] The thermoelectric elements may be made of silicon (Si), of a silicon and germanium alloy (SiGe), bismuth telluride (Bi2Te3), skutterudites, of a Half Heusler alloy or of lead telluride.

[0040] Arrangement of the thermoelectric elements with respect to each other

[0041] The thermoelectric elements can be inclined on the substrate with respect to the axis perpendicular to the substrate at their base.

[0042] Preferably, the thermoelectric elements connected by a mixing electrical junction are inclined on the substrate with respect to the axis perpendicular to the substrate at their base in opposite directions. They may be inclined with respect to the axis perpendicular to the substrate at their base by the same angle α, in particular between 5° and 70°. The angle may depend, in particular, on the expected thermoelectric performance, the required mechanical strength, the materials, and / or the height of the elements. In the case of a cylindrical substrate with a circular cross-section, the angle α may be approximately equal to 720 / n, where n is the number of thermoelectric elements arranged around a cross-section of the substrate. Shape of thermoelectric elements

[0043] The thermoelectric elements are each preferably elongated along a longitudinal axis.

[0044] Preferably, the thermoelectric elements are each symmetrical with respect to their longitudinal axis.

[0045] The thermoelectric elements may each be symmetrical with respect to their median axis perpendicular to the longitudinal axis. Alternatively, the thermoelectric elements may each be asymmetrical with respect to said median axis.

[0046] Thermoelectric elements can all be substantially the same shape.

[0047] In the case of thermoelectric elements that are asymmetric with respect to their median axis. The thermoelectric elements connected by a mixing electrical junction can have complementary shapes, in particular, substantially interlocking shapes. This allows, in particular, for the thermoelectric elements to be brought closer together, which reduces their size and allows for a greater number of thermoelectric elements per unit area. Alternatively, the thermoelectric elements connected by a mixing electrical junction can be arranged in the same orientation.

[0048] Alternatively, at least two thermoelectric elements are of different shapes, in particular the thermoelectric elements connected together by an electrical mixing junction are of different shapes, in particular complementary.

[0049] Thermoelectric elements may be cylindrical in shape with any base and a lateral surface extending onto the substrate. The base of the cylinder may be in the shape of a quadrilateral, in particular a rectangle or an isosceles trapezoid, an hourglass symmetrical or asymmetrical with respect to the median plane, a circular sector in the form of blocks of substantially parallelepiped shape, or have a surface at their base that is less than or equal to

[0050] Thermoelectric elements may have, between the base and the apex, a localized narrowing having a lateral width less than the width of the apex and / or the base.

[0051] Thermoelectric elements may have a surface at their base that is different from the surface at their top, in particular one of the two surfaces may be larger than the other for a substantially identical contour or vice versa.

[0052] Thermoelectric elements may have branches extending towards the base and / or the apex. The branches may be inclined relative to each other. The branches may join at their base. Thermoelectric elements may be Y-shaped or X-shaped. Alternatively, the branches may be spaced apart along their entire height.

[0053] Thermoelectric elements can be hollow or solid.

[0054] Thermoelectric elements may have recesses, in particular lateral notches along their height or a recess at their base or top. This makes it possible, in particular, to lighten the thermoelectric module, reduce the amount of material used, and increase the temperature difference between the top and the base of the thermoelectric elements under operating conditions.

[0055] The base of the thermoelectric elements may be of complementary shape to the substrate, in particular be a curved surface in the case of a cylindrical substrate with a circular base having the same radius of curvature as the substrate.

[0056] The apex of the thermoelectric elements can be a flat or curved surface. The curved surface of the apex can have the same radius of curvature as the substrate. Concentrated energy deposition method

[0057] Concentrated energy deposition can be performed using a device comprising a single nozzle for projecting the material to be deposited or a plurality of nozzles for projecting the material to be deposited. As mentioned previously, the presence of multiple nozzles allows for the deposition of different materials by different nozzles. In particular, this makes it possible to form p-doped and n-doped thermoelectric elements without having to change the powder in the device, using different nozzles. This simplifies manufacturing and improves manufacturing and junction accuracy. This can improve the energy performance of the thermoelectric module, notably by reducing electrical resistance at internal and / or external electrical junctions. Simultaneous filing

[0058] In the case of a plurality of projection nozzles, at least two nozzles may be connected to separate reservoirs, in particular each nozzle being connected to its own reservoir. In this case, the nozzles connected to separate reservoirs may be supplied with material from the reservoir independently.

[0059] Preferably, in this case, at least one or more first nozzles are connected to one or more reservoirs containing an n-type doped material to form one of the thermoelectric elements connected to each other by an electrical mixing junction. at least in part and at least one or more other second nozzles are connected to one or more tanks containing a p-type doped material to form the other of the thermoelectric elements connected together by an electrical mixing junction at least in part.

[0060] The first and second nozzles can be controlled independently or synchronously to deposit only one of the two materials or a mixture of the two materials. This limits the handling of the deposition device for the formation of the thermoelectric module, as the differently doped materials for the thermoelectric elements can be introduced upstream into the deposition device, and the deposition can be performed by programming without external intervention. This also improves the positioning accuracy of the thermoelectric elements and, in particular, enables more precise electrical mixing junctions and therefore better connection quality.

[0061] It is thus possible to deposit only the p-type material, in particular to form at least part of one thermoelectric element, or only the n-type material, in particular to form at least part of the other thermoelectric element, or to deposit a mixture of the n- and p-type materials to form the electrical mixing junction between the thermoelectric elements. Thus, the deposition of the two thermoelectric elements can be carried out at least partially by projecting two materials doped with different types of doping through different nozzles of the concentrated energy deposition device. Therefore, the electrical mixing junction(s) can be formed between two thermoelectric elements by the simultaneous deposition of the two different doped materials through the first and second nozzle(s).

[0062] The thermoelectric elements can be formed, at least in part, by the alternating deposition of a p-type doped material and an n-type doped material by alternating the material being sprayed through the first nozzle(s) and the second nozzle(s). This makes it possible, in particular, to manufacture the module, at least partially, without having to manipulate the deposition device, and it allows for better identification of the thermoelectric elements relative to each other.

[0063] The alternating projections by the first nozzle(s) and the second nozzle(s) as described above may include overlapping areas of material projection by the first and second nozzle(s) to form the electrical mixing junctions as described above. This allows, in particular, for electrical connections to be formed during the deposition process of the thermoelectric elements, at least partially through material continuity, and specifically eliminates the need for connections via additional metallic tracks.

[0064] In the case of multilayer thermoelectric elements, the process may comprise a. the deposition under concentrated energy of the base of the thermoelectric elements in a first material with optionally the electrical mixing junctions at the base on the support or on conductive tracks as described previously, b. the deposition, by any suitable method, of the interface structure onto the parts of the thermoelectric elements formed, then, c. deposition by concentrated energy deposition of the top of the thermoelectric elements in a second material different from the first with optionally the mixing electrical junctions at the top of the thermoelectric elements as described previously.

[0065] In the case of additional intermediate layers in a thermoelectric material, the process may additionally include, between steps b) and c), as many times as there are intermediate layers, the deposition under concentrated energy of the layer of thermoelectric elements in an additional material on the interface structure deposited previously as described above, and then the deposition by any suitable method of an interface structure on the parts of the thermoelectric elements formed previously.

[0066] The process may include changing the material in the reservoirs of the concentrated energy deposition device for each deposition step. Alternatively, the device may include at least as many reservoirs as there are materials required for concentrated energy deposition, and the various deposition steps described above are carried out using different nozzles. Successive deposit

[0067] Alternatively, all the nozzles can be connected to the same reservoir of material to be deposited. It is then necessary to change the material for each new material and each type of doping. The process may include at least one step of changing the material to be deposited in the concentrated energy deposition device.

[0068] Alternatively, the thermoelectric elements can be formed by depositing different materials and different dopings one after the other, depending on the structure of the thermoelectric elements. In the case of thermoelectric elements made of a single material, the process can involve, in a first step, the deposition of all the p-type doped thermoelectric elements, followed by the deposition of all the n-type doped thermoelectric elements in a second step. The deposition of the mixing electrical junction can be carried out independently in one or more additional steps, each before or after the first step and before or after the second step. This can be done by changing the material to be deposited in The concentrated energy deposition device, particularly in the case of a single reservoir for all nozzles, and / or by controlling the deposition via different nozzles. Formation of electrical tracks

[0069] The process may include a step of depositing metallic tracks on the substrate and / or on the thermoelectric elements to form part of the internal and / or external electrical junctions.

[0070] The process may include depositing on the substrate, prior to the deposition of the thermoelectric elements, a discontinuous metallic layer to form at least part of the electrical junctions on the substrate side in the form of conductive tracks.

[0071] The method may include depositing on the thermoelectric elements, after the deposition of the thermoelectric elements, a discontinuous metallic layer to form at least part of the electrical junctions on the side opposite the substrate in the form of conductive tracks. Substrate

[0072] The substrate is preferably made of an insulating material. It can be made of ceramic, in particular AIN, mullite, CN.

[0073] The substrate may be cylindrical in shape with a polygonal base, in particular rectangular, square, pentagonal or hexagonal, circular or elliptical.

[0074] Alternatively, the substrate may be of another shape, in particular forming a flat or convex surface or a more complex surface. Thermoelectric circuit

[0075] The module may comprise a plurality of adjacent thermoelectric elements electrically connected to each other to form a thermoelectric circuit, each thermoelectric element being electrically connected on the substrate side and / or opposite the substrate to another thermoelectric element by an electrical junction formed by a layer of a mixture of the two materials doped according to different types of doping composing the two thermoelectric elements.

[0076] Preferably, the module forms a thermoelectric circuit between a first thermoelectric element and a last thermoelectric element, the first and last thermoelectric elements being electrically connected by one of their ends to an electrical connector and the thermoelectric elements between the first and last thermoelectric elements being all electrically connected to at least two adjacent thermoelectric elements to form the thermoelectric circuit between them by electrical junctions formed by a layer of a mixture of the two materials doped according to different types of doping composing the two thermoelectric elements.

[0077] Alternatively, the module forms a thermoelectric circuit between a first thermoelectric element and a last thermoelectric element, the first and last thermoelectric elements being electrically connected by one of their ends to an electrical connector and the thermoelectric elements between the first and last thermoelectric element being all electrically connected to at least two adjacent thermoelectric elements to form the thermoelectric circuit between them by an electrical connector on one side of the substrate or on the side opposite the substrate and by an electrical junction formed by a layer of a mixture of the two materials doped according to different types of doping composing the two thermoelectric elements on the other side of the substrate or on the side opposite the substrate.

[0078] In the case of a cylindrical substrate, the thermoelectric elements can be arranged in circumferential rows in which the thermoelectric elements are electrically connected to each other, two thermoelectric elements of each circumferential row being electrically connected to a thermoelectric element nearest to a front row and a back row along the longitudinal axis of the substrate respectively, with the exception of the first and last circumferential rows which are each connected to an electrical connector.

[0079] Alternatively, the thermoelectric elements can be arranged in longitudinal rows in which the thermoelectric elements are electrically connected to each other, the first and last thermoelectric element of each longitudinal row being electrically connected to the nearest thermoelectric elements of the adjacent longitudinal rows except for two adjacent longitudinal rows each connected to an electrical connector. Support structure

[0080] The process may include depositing a support structure onto the substrate, the support structure comprising support elements configured to extend between the thermoelectric elements, forming a bridge between them and serving as a support for the deposition of the thermoelectric elements during their deposition under concentrated energy. This deposition is preferably carried out prior to the deposition of the thermoelectric elements under concentrated energy.

[0081] The support elements may include an electrically insulating material and / or a sacrificial material.

[0082] In the case of thermoelectric elements inclined with respect to the axis perpendicular to the substrate at their base, the support elements can extend beneath the thermoelectric elements. This facilitates the deposition of the thermoelectric elements by deposition under concentrated energy.

[0083] In the case of thermoelectric elements in contact with each other, the support elements can extend between the TE elements in contact with each other at their apex.

[0084] Preferably, the support elements are all identical and made of the same material.

[0085] They can be deposited on the substrate by any suitable method, in particular by 3D printing, particularly using the concentrated energy deposition method. At least one of the nozzles of the concentrated energy deposition device can be connected to a reservoir containing the material constituting the support elements.

[0086] The support elements may have a thermal conductivity less than or equal to that of the thermoelectric elements.

[0087] The support elements may be made of an electrically insulating material. The electrically insulating material may be a ceramic, in particular silica, mica or Macor®. The ceramic may be solid or porous.

[0088] Alternatively, the support elements are made of a sacrificial material, the process further comprising a step of removing the sacrificial material by a suitable method, in particular by chemical means or by heating. The sacrificial material may be ceramic or metal, in particular silica or aluminum nitride. Thus, it is possible to have support elements that are only visible during the manufacturing process but are no longer visible on the thermoelectric module and form hollow areas.

[0089] Alternatively, the support elements may have a more complex structure, in particular comprising a skin layer and a core layer. The skin layer may be made of an electrically insulating material and the core layer of a sacrificial material. Additional steps

[0090] The process may include, after the formation of the thermoelectric elements and the electrical mixing junctions, an annealing step. The annealing step may involve heating the formed module to a temperature greater than or equal to 100°C in a furnace under an inert atmosphere, in particular an argon atmosphere. Such annealing makes it possible, in particular, to modify the microstructure of the thermoelectric elements and the electrical mixing junction to improve the microstructure of the formed module. This can also make it possible to reduce the mechanical stresses accumulated in the module during manufacturing and thus improve the mechanical and thermoelectric properties of the thermoelectric module. Brief description of the drawings

[0091] [Fig. 1] schematically represents in cross-section an example of a cylindrical thermoelectric module,

[0092] [Fig.2] schematically represents in cross-section a variant of a thermoelectric module,

[0093] [Fig.3] schematically represents a variant of a thermoelectric module,

[0094] [Fig.4] schematically represents different variants of thermoelectric pad shapes,

[0095] [Fig.5] schematically represents in cross-section a variant of a thermoelectric module,

[0096] [Fig.6] schematically represents in cross-section a variant of a thermoelectric module,

[0097] [Fig.7] schematically represents in cross-section a variant of a thermoelectric unit,

[0098] [Fig.8] schematically represents an example of a process,

[0099] [Fig.9] schematically represents a variant of the process.

[0100] [Fig. 10] schematically represents a variant of the process,

[0101] [Fig. 11] schematically represents an example of a support structure, and

[0102] [Fig. 12] schematically represents a variant of the process. Detailed description

[0103] In the following description, identical elements or elements with identical functions 10 bear the same reference numeral. For the sake of brevity in this description, they are not described opposite each of the figures; only the differences between the embodiments are described.

[0104] Figure 1 illustrates a thermoelectric module (10) comprising a cylindrical substrate (20) with a circular base, carrying thermoelectric elements (11, 12) electrically connected to each other by electrical junctions (32, 31). The substrate is preferably made of an insulating material. It may be ceramic, in particular AIN, mullite, or CN.

[0105] The thermoelectric elements (11, 12) electrically connected to each other are of different dopings so that the thermoelectric elements (11, 12) are of alternating dopings on the substrate (20).

[0106] In the embodiment of [Fig. 1], the thermoelectric elements (11, 12) are identical in shape. The invention is not limited to thermoelectric elements (11, 12) of identical shape. These could have different shapes or be identical but arranged head-to-tail, as will be seen later.

[0107] The thermoelectric elements (11, 12) are each in the form of elongated pads along an elongation axis. At least one of the electrical junctions of the base (32) or the apex (31) is a mixing electrical junction formed by a mixture of the two materials of the thermoelectric elements that it connects. Preferably, all electrical junctions of the base of the thermoelectric elements (32) and / or all electrical junctions of the top of the thermoelectric elements (31) are mixing electrical junctions.

[0108] All electrical junctions of the base of the thermoelectric elements (32) and of all electrical junctions of the top of the thermoelectric elements (31) may be mixing electrical junctions. Alternatively, one of all the electrical junctions of the base of the thermoelectric elements (32) and of all the electrical junctions of the top of the thermoelectric elements (31) are mixing electrical junctions and the other of all the electrical junctions of the base of the thermoelectric elements (32) and of all the electrical junctions of the top of the thermoelectric elements (31) are metallic tracks formed by a discontinuous metallic layer deposited on the thermoelectric elements (11, 12) or on the substrate (20).

[0109] In the illustrated example, the thermoelectric elements (11, 12) have elongation axes different from a radial axis, forming an angle α between them of between 5° and 70°. The angle α is approximately equal to 720 / n, where n is the number of thermoelectric elements arranged around a cross-section of the substrate, here approximately equal to 45°. In this case, the contact surface (17) between the thermoelectric elements is preferably greater than or equal to 50% of the cross-section of a thermoelectric element. Each thermoelectric element can form an angle θ with the radial axis at its base that is approximately equal to the angle α. In the illustrated example, all the thermoelectric elements form the same angle with the radial axis.However, it could be otherwise; in particular, the thermoelectric elements of one doping could form a first angle, and the thermoelectric elements of the other doping could form a second angle different from the first with their radial axis. In this embodiment, the thermoelectric elements are connected to each other by contact at their base and by a mixture of the materials composing the two thermoelectric elements (11, 12) at their apex, as can be seen in more detail in [Fig. 2], shown in plan view. This junction (40) can be formed by using a concentrated energy deposition device comprising several nozzles connected to different reservoirs containing the p-doped material and the n-doped material, respectively, and by simultaneously spraying the two materials onto the junction between the two thermoelectric elements (11, 12).The manufacturing process can then include a sequence of projections coordinated with the movement of the nozzles on the substrate comprising a first projection of a material of a first doping to form a first thermoelectric element (11) by the first nozzle(s), then a second projection of a material of a second doping to. to form a second thermoelectric element (12) by the second nozzle(s), the first and second projection being simultaneous at the junction between the two thermoelectric elements (11, 12) to form the junction (40) by mixing the two materials. Preferably, the materials forming the thermoelectric elements are identical. Only their doping differs.

[0110] The thermoelectric elements may be made of thermoelectric materials, such as silicon (Si), a silicon-germanium alloy (SiGe), bismuth telluride (Bi2Te3), skutterudites, a Half Heusler alloy, or lead telluride. Each thermoelectric element (11, 12) is connected at its apex by an electrical junction (31) to an adjacent thermoelectric element (11, 12) and at its base by an electrical junction (32) to another adjacent thermoelectric element (11, 12), so as to form a thermoelectric circuit around and on the substrate (20).

[0111] In this embodiment, the thermoelectric elements (11, 12) are connected in series, each thermoelectric element (11, 12), with the exception of the first and last thermoelectric elements in the series, being connected at its base to an adjacent thermoelectric element by one of the electrical junctions (32) and at its apex to another adjacent thermoelectric element by one of the electrical junctions (31). The first and last thermoelectric elements in the series are each connected to an adjacent thermoelectric element by one of their bases and apexes and to an external electrical connector, not shown, by the other of their bases and apexes.The thermoelectric elements (11, 12) can be arranged in circumferential rows in which the thermoelectric elements are electrically connected to each other by electrical junctions (31, 32), two thermoelectric elements (11a, 12a) of each circumferential row being electrically connected to a thermoelectric element nearest to a front row and a back row along the longitudinal axis of the substrate respectively, with the exception of the first and last circumferential rows which are each connected to an electrical connector.

[0112] The thermoelectric module (10) of [Fig.3] differs from the previous modules illustrated in that the thermoelectric elements are no longer inclined with respect to the support and the support is flat and the junction at the base or top is a mixture of the two materials to make a planar connection.

[0113] The invention is not limited to a particular shape of the thermoelectric elements (11, 12). Many different shapes can be considered. Figure 4 shows some of them. On the upper line, from a to i, the shapes correspond to thermoelectric elements deposited on a flat surface of the substrate (20), and on the lower line, from j to q, to ​​thermoelectric elements deposited on a curved surface of the substrate (20). Nevertheless, the shapes of the line The upper sections are suitable for deposition on a curved surface with adjustments to the base, and the lower sections are suitable for deposition on a flat surface with minor adjustments within the capabilities of a person skilled in the art. The thermoelectric elements preferably extend along a longitudinal axis (X). Thermoelectric elements a, b, e, and i are symmetrical about their median plane perpendicular to their longitudinal axis (X). Thermoelectric elements c, d, f, and g are not symmetrical about their median plane (Y) perpendicular to the longitudinal axis X. Thermoelectric element b has lateral recesses of thickness v and depth w. Thermoelectric elements c and d each have different surfaces at their base and apex. Thermoelectric elements c and d have complementary shapes and can be alternately aligned to bring the thermoelectric elements closer together.The thermoelectric element e has a lateral width between its apex and base that is less than the combined width of its apex and base, thus being hourglass-shaped. The thermoelectric elements f, g, and i have branches that extend towards the base for element f, towards the apex for element g, and towards both the apex and the base for element i, in an X shape.

[0114] The thermoelectric elements i, j, k, l, m, n, o, p, q correspond to the elements a, b, c, d, e, f, g, h, adapted to a contact surface of the curved substrate on which they are deposited. In this case, the substrate has a curved surface and the thermoelectric elements preferably have the same radius of curvature at their base and apex as the substrate.

[0115] Figure 5 illustrates a thermoelectric module (10) with a flat substrate surface (20). The differently doped thermoelectric elements (11, 12) have different shapes. Two adjacent thermoelectric elements comprise a trapezoidal thermoelectric element (11) with its longer side forming the base and a trapezoidal thermoelectric element (11) with its longer side forming the apex. The thermoelectric elements (11, 12) have complementary lateral surfaces.

[0116] In the variant illustrated in [Fig.6], the thermoelectric elements (11, 12) are here each in the form of an elongated pad along a longitudinal axis, corresponding to a radial axis of the substrate (20) and are symmetrical with respect to this longitudinal axis. The thermoelectric elements (11, 12) increase in width along the longitudinal axis from their base to their apex. In cross-section with the substrate, they have straight lateral walls (34) extending radially from the substrate (20). This helps to limit the gaps between the thermoelectric elements (31, 32).

[0117] Figure 7 illustrates a variant of a thermoelectric module (10) in which the first thermoelectric element (11) and the second thermoelectric element (12) are each formed from two pads (11a, 11b; 12a, 12b) of the same doping, preferably made of the same material. The two pads of each element are electrically connected to each other in parallel on the substrate side and on the opposite side. These junctions can be formed by continuity of material or by metallic electrical connectors. The thermoelectric elements (11, 12) of different dopings are, for their part, connected alternately around the substrate to each other on the opposite side (31) and on the substrate side (32). At least one of the electrical junctions between thermoelectric elements on the substrate side and on the opposite side is formed by a mixture of the material of the two adjacent thermoelectric elements.The invention is not limited to one or two pads per thermoelectric element. The thermoelectric elements may have more than two pads depending on the required performance and specifications. The invention is also not limited to the same number of pads for both thermoelectric elements. The first element could, for example, have a single pad and the second element could have two pads.

[0118] Figure 8 illustrates a method for manufacturing a variant of a thermoelectric module (10). The thermoelectric module (10) formed is similar to that of Figure 7. The only differences are that the substrate (20) is hexagonal in cross-section and not circular as in Figure 7, and that the thermoelectric elements (11, 12) are parallelepiped-shaped and therefore of constant width along their entire height. Each face (22) of the substrate carries one or more pairs of adjacent thermoelectric elements (11, 12), here two pairs of adjacent thermoelectric elements (11, 12). The pairs of adjacent thermoelectric elements (11, 12) with different bases are connected to each other by junctions (32) at their base extending between the two corresponding faces. In this embodiment, the pairs of adjacent thermoelectric elements are each located on one face.Nevertheless, it is possible, without departing from the scope of this invention, to have one or more pairs of adjacent thermoelectric elements (11, 12) straddling two adjacent faces.

[0119] In this manufacturing process, the first step (100) consists of providing the substrate (20) onto which the electrical junctions (32) are deposited in a second step (110). The deposition of the electrical junctions can be carried out in one or more layers by any deposition method.

[0120] The thermoelectric elements (11, 12) are then deposited in step (120) onto the electrical connections (32). The deposition of the thermoelectric elements (11, 12) is achieved by a concentrated energy deposition method using a suitable device.

[0121] The concentrated energy deposition device may comprise a plurality of nozzles, at least one or more of the first nozzles being connected to a reservoir of powder in a p-doped material and one or more second nozzles being connected to a reservoir of n-doped powder. The deposition of the thermoelectric elements (11, 12) can then be carried out by successive deposition of adjacent thermoelectric elements (11, 12) onto the electrical junctions (32). The first nozzle(s) can then project the p-doped material to form a thermoelectric element (11), then the second first nozzle(s) can project the n-doped material to form an adjacent thermoelectric element (12), and so on until all the thermoelectric elements (11, 12) have been formed. Alternatively, the deposition step comprises the deposition of all the thermoelectric elements of one doping and then the deposition of all the thermoelectric elements of the other doping.

[0122] Alternatively, the concentrated energy deposition device comprises a single nozzle or all of its nozzles are connected to one or more reservoirs containing a doped material. The deposition process is then similar to that described above, except that the reservoir(s) and / or the contents of the reservoir(s) must be changed in order to depose the thermoelectric elements of both dopings.

[0123] Finally in step 130, the electrical junctions (31) are formed by mixing the materials of the two adjacent thermoelectric elements on the thermoelectric elements (11,12) to connect the thermoelectric elements to each other at their vertices, in the present case to connect the adjacent thermoelectric elements (11, 12) to each other.

[0124] The process may include, after the formation of the adjacent thermoelectric elements (11, 12), an additional annealing step not shown. The annealing step may include heating the formed module to a temperature greater than or equal to 100°C under an inert atmosphere, in particular Argon.

[0125] Figure 9 illustrates a method for manufacturing a module (10), comprising supplying a substrate (20) according to step 100, then in step 105 depositing a support structure (25) onto the substrate (20), followed by the deposition of the thermoelectric elements (11, 12) by concentrated energy deposition in the same form as in Figure 1, i.e., by mixing junction. The support structure (25) comprises support elements deposited at regular intervals on the substrate (20) which facilitate the fabrication of the thermoelectric elements inclined with respect to the radial axis by allowing their formation directly on the surface of these support structures (25). Preferably, the support structures (25) have a shape complementary to the spaces under the thermoelectric elements, in particular triangular. The deposition of the support structure can be made by any known means. Preferably, such support elements can have a thermal conductivity less than or equal to that of the thermoelectric elements (11, 12), in particular made of an insulating material, for example ceramic or silica, solid or porous.

[0126] Figure 10 illustrates a method for manufacturing a thermoelectric module (10) similar to that shown in Figure 9. In this embodiment, the support structure is formed of sacrificial elements (28) made of a sacrificial material. The method may then include a step 135 of removing the sacrificial material by a suitable method, in particular by chemical means or by heating. The sacrificial material may be ceramic or metal, in particular silica or aluminum nitride.

[0127] In the variant illustrated in [Fig. 11], the support structure comprises an inner part (28a) made of a sacrificial material and an outer part (28b) made of a non-sacrificial material. In step 105, the inner part (28a) made of sacrificial material is deposited onto the substrate (20), followed by a second deposit of a second material covering the sacrificial material (28b). In a subsequent step, the inner part (28a) of the support structure (25) is removed, leaving only the outer part (28b) of the support structure. The removal step may occur after the formation of the thermoelectric elements or afterward.

[0128] Figure 12 illustrates another method for manufacturing a variant of a thermoelectric module. The thermoelectric module (10) differs from that of Figure 1 in that each thermoelectric element (11, 12) is formed of a multilayer structure comprising, from base to top, a first layer (11i, 12i) of a first material deposited in step 120a by concentrated energy deposition as described previously, an interface (70) of a layer of one or more materials forming a diffusion barrier deposited by any means in step 125, in particular of copper or nickel, and a second layer (11ii, 12ii) of a second material deposited in step 120b by concentrated energy deposition as described previously. The invention is not limited to a multilayer structure comprising only two layers. A more complex structure is possible by successive depositions.

[0129] The invention is not limited to the examples just described. A person skilled in the art will be able to combine the lessons learned from the different embodiments to produce undescribed variants.

[0130] For example, the thermoelectric elements in Figures 1 and 2 can each be of a multilayer structure as described in relation to [Fig. 12].

Claims

Demands

1. Thermoelectric module (10), comprising, - a substrate (20), - at least two adjacent thermoelectric elements (11, 12) made of two materials doped with different types of doping extending over the substrate and electrically connected to each other on the side of the substrate (20) and / or opposite the substrate (20) by a mixing electrical junction formed by a layer of a mixture of the two materials doped with different types of doping composing the two thermoelectric elements (11, 12).

2. Thermoelectric module (10) according to claim 1, the two thermoelectric elements (11, 12) being made of the same material doped with different types of doping, in particular doped respectively p and n.

3. Thermoelectric module (10) according to any one of the preceding claims, the two thermoelectric elements (10) being elongated along a longitudinal axis (X).

4. Thermoelectric module (10) according to any one of the preceding claims, the thermoelectric elements (11, 12) being inclined on the substrate (20) with respect to the axis perpendicular to the substrate (20) at their base in opposite directions, in particular at an angle [3] between 5° and 70°, the angle being able to depend on the expected thermoelectric performance, the required mechanical strength, the materials and / or the height of the elements.

5. Thermoelectric module (10) according to any one of the preceding claims, the electrical junction of mixing the two materials composing the two thermoelectric elements extending between two lateral surfaces of the thermoelectric elements (11, 12) opposite each other.

6. Thermoelectric module (10) according to any one of the preceding claims, the area of ​​the electrical mixing junction along a median plane to the two thermoelectric elements (11, 12) being greater than or equal to 50%, or better, greater than or equal to 70%, of the area of ​​a cross-section of a thermoelectric element.

7. A module according to any one of the preceding claims, comprising a plurality of adjacent thermoelectric elements (11, 12) electrically connected to each other to form a circuit thermoelectric, each thermoelectric element being electrically connected on the substrate side (20) and / or opposite the substrate (20) to another thermoelectric element (11, 12) by an electrical junction formed by a layer of a mixture of the two materials doped according to different types of doping component the two thermoelectric elements (11, 12).

8. Module according to claim 7, wherein the first and last thermoelectric elements of the thermoelectric circuit are electrically connected by one of their ends to an electrical connector and the thermoelectric elements between the first and last thermoelectric element are all electrically connected to at least two adjacent thermoelectric elements to form the thermoelectric circuit between them by electrical junctions formed by a layer of a mixture of the two materials doped according to different types of doping component the two thermoelectric elements (11,12).

9. Module according to claim 8, wherein the first and last thermoelectric elements of the thermoelectric circuit are electrically connected by one of their ends to an electrical connector and each thermoelectric element between the first and last thermoelectric element is electrically connected to at least two adjacent thermoelectric elements to form the thermoelectric circuit between them by an electrical connector on one side of the substrate or the side opposite the substrate and by electrical junctions formed by a layer of a mixture of the two materials doped according to different types of doping components the two thermoelectric elements (11, 12) on the other side of the substrate or the side opposite the substrate.

10. Thermoelectric module (10) according to any one of the preceding claims, the thermoelectric elements (11, 12) being electrically connected in series with each other on one side of the substrate (20) and on the opposite side of the substrate (20) only.

11. Thermoelectric module (10) according to any one of the preceding claims, the thermoelectric elements (11, 12) comprising several layers of different materials doped with the same type of doping, in particular separated from each other by interface structures (70).

12. Thermoelectric module (10) according to any one of claims 1 to 10, at least two of the thermoelectric elements being electrically connected to each other on the substrate side and on the side opposite the substrate.

13. Thermoelectric module (10) according to any one of the preceding claims, the substrate (20) being cylindrical in shape with a polygonal base, in particular rectangular, square, pentagonal or hexagonal, circular or elliptical.

14. Thermoelectric module (10) according to any one of the preceding claims, comprising a support structure on the substrate, the support structure comprising support elements, in particular made of an electrically insulating material, extending between the thermoelectric elements forming a bridge between them.

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