WO2025179378A1

WO2025179378A1 - Capillary casted thermoelectric p/n junction

Info

Publication number: WO2025179378A1
Application number: PCT/CA2025/050245
Authority: WO
Inventors: Michael ABDELMASEH
Original assignee: Pyrodelta Energy Inc
Current assignee: Pyrodelta Energy Inc
Priority date: 2024-02-26
Filing date: 2025-02-25
Publication date: 2025-09-04
Anticipated expiration: 2026-08-26

Abstract

A thermoelectric p/n junction, and more particularly multiple interlocking junctions, manufactured using capillary casting. A conductive substrate is sandwiched between a pair of barriers. The conductive substrate includes a mold delineated by the substrate's periphery. While the substrate is sandwiched, at least a portion of the mold is submerged into a tellurium-based molten alloy that is at a higher temperature than the substrate. This results in molten alloy being drawn into the mold by capillary action. The molten alloy is solidified by removing the sandwiched substrate from the molten alloy. The conductive substrate acts as one of a negatively or positively doped material of the p/n junction and the solidified alloy acts as the other of the negatively or positively doped material of the p/n junction. Multiple of these junctions may be designed to interlock with each other to form a thermoelectric generator.

Description

CAPILLARY CASTED THERMOELECTRIC P/N JUNCTION

TECHNICAL FIELD

[0001] The present disclosure is directed to a thermoelectric p/n junction, and more particularly to multiple interlocking junctions, manufactured using capillary casting.

BACKGROUND

[0002] The quest for efficient energy conversion technologies has long been a significant driver of innovation, particularly in the field of renewable energy sources. Photovoltaic (PV) cells, which convert sunlight directly into electricity, have become increasingly prevalent due to their improving efficiency and scalability. However, despite these advancements, PV cells possess inherent limitations, particularly in contexts where environmental conditions or spatial constraints make their viability challenging. In areas with inconsistent sunlight, high-latitude regions with extended periods of darkness, or urban environments where space is at a premium, for example, the deployment of PV cells is often not cost-effective or practical.

SUMMARY

[0003] According to a first aspect, there is provided a method for manufacturing a p/n junction for a thermoelectric generator, the method comprising: sandwiching a conductive substrate between a pair of inert barriers, wherein the conductive substrate comprises a mold delineated by a periphery of the substrate; while the substrate is sandwiched, submerging at least part of the mold into a tellurium-based molten alloy at a higher temperature than the substrate, wherein submerging the mold into the molten alloy results in the molten alloy being drawn into the mold by capillary action; and solidifying the molten alloy by removing the substrate from the molten alloy, wherein the conductive substrate acts as one of a negatively or positively doped material of the p/n junction and the solidified alloy acts as the other of the negatively or positively doped material of the p/n junction.

[0004] The conductive substrate may act as the positively doped material and the solidified alloy may act as the negatively doped material. Alternatively, the conductive substrate may act as the negatively doped material and the solidified alloy may act as the positively doped material. [0005] The conductive substrate may be copper.

[0006] The pair of barriers may be ceramic. The ceramic may be alumina ceramic.

[0007] The barriers and the conductive substrate may be coplanar with each other.

[0008] The conductive substrate and the barriers may be tubular, and the barriers may respectively extend within and outside of the conductive substrate.

[0009] The molten alloy may further comprise antimony.

[0010] The molten alloy may further comprise micron-sized or smaller glass powder.

[0011] The molten alloy may comprise 3 parts of the tellurium, 1.5 parts of the antimony, and 0.1 parts of the micron-sized glass powder.

[0012] The molten alloy may further comprise bismuth.

[0013] The molten alloy may comprise 3 parts of the tellurium, 1.5 parts of the antimony, 0.5 parts of the bismuth, and 0.1 parts of the micron-sized glass powder.

[0014] Prior to the submerging, the substrate may comprise multiple disconnected segments; during the submerging, the molten alloy may also be drawn between the segments; and the mold may be shaped such that after the solidifying, the segments are secured together by virtue of the solidified alloy interlocking the segments together.

[0015] During the submerging the molten alloy may enter the mold through a gate, and a width of the gate may be less than a maximum width of the mold.

[0016] According to another aspect, there is provided at least one p/n junction for a thermoelectric generator, the at least one junction comprising: a conductive substrate comprising multiple segments spaced apart from each other; and one or more casts of a tellurium-based alloy between respective one or more pairs of segments, wherein each of the one or more casts interlocks a respective one of the one or more pairs of segments together, and wherein the conductive substrate acts as one of a negatively or positively doped material of the p/n junction and the solidified alloy acts as the other of the negatively or positively doped material of the p/n junction.

[0017] The conductive substrate may be copper. [0018] The alloy may comprise 3 parts tellurium, 1.5 parts antimony, 0.5 parts bismuth, and 0.1 parts micron-sized glass powder.

[0019] The conductive substrate may be tubular. Alternatively, the conductive substrate may be planar.

[0020] Each of the multiple segments may comprise a mold and a gate that contain a portion of one of the one or more casts, and a width of the gate may be less than a maximum width of the mold.

[0021] According to another aspect, there is provided a thermoelectric generator that comprises multiple of the above p/n junctions electrically connected in series and/or parallel.

[0022] This summary does not necessarily describe the full scope of all aspects. Other aspects, features and advantages will become apparent to those of ordinary skill in the art upon review of the following description of specific embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In the accompanying drawings, which illustrate one or more example embodiments:

[0024] FIGS. 1A and IB are front elevation and perspective views, respectively, of a conductive substrate for use in manufacturing a series of thermoelectric p/n junctions, according to an example embodiment.

[0025] FIGS. 2A and 2B respectively show how the conductive substrate of FIGS. 1A and IB is sandwiched between two barriers as part of the process for manufacturing the series of p/n junctions, according to an example embodiment.

[0026] FIG. 3 shows how the sandwiched conductive substrate of FIG. 2B is submerged into and then removed from a molten alloy in order to cast the series of thermoelectric p/n junctions using capillary casting, according to an example embodiment.

[0027] FIGS. 4A and 4B are front elevation and perspective views, respectively, of a thermoelectric generator comprising a series of thermoelectric p/n junctions that results from the capillary casting of FIG. 3. [0028] FIG. 5A is a perspective view of a conductive substrate for use in capillary casting a tubular thermoelectric generator, according to an example embodiment.

[0029] FIG. 5B is a perspective view of a series of the conductive substrates of FIG. 5 A immediately prior to capillary casting, and of tubular barriers for use in sandwiching the series of conductive substrates during capillary casting, according to an example embodiment.

[0030] FIG. 6 shows an array of thermoelectric generators manufactured through repeatedly performing the capillary casting of FIG. 3, according to an example embodiment.

[0031] FIG. 7 shows the thermoelectric generator of FIG. 6 used to generate electricity in combination with a heat source and heat sink, according to an example embodiment.

DETAILED DESCRIPTION

[0032] Thermoelectric generators (TEGs), which generate electricity from heat differentials via the Seebeck effect, offer a compelling alternative to PV cells and are able to generate electricity from heat differentials that would otherwise be wasted. Unlike PV cells, TEGs do not rely on sunlight, allowing them to operate in a variety of conditions, including indoors or at night. This makes them suitable for applications such as waste heat recovery systems in automotive or industrial settings, for example, where they can capitalize on thermal gradients that would otherwise be unused and lost as waste heat.

[0033] Despite their potential, the widespread adoption of TEGs has been hindered by manufacturing challenges. Conventionally, TEGs are manufactured by sintering pellets made from an amalgam of thermoelectric materials, which often results in an inhomogeneous mixture and a propensity for material cracking. Additionally, sintering necessitates precise assembly and uses environmentally hazardous materials, leading to high production costs that have made TEGs less attractive compared to their photovoltaic counterparts.

[0034] The present disclosure addresses these manufacturing obstacles by applying a "capillary casting" method to manufacture TEGs. This technique significantly reduces the costs associated with TEG production relative to the conventional sintering method for TEGs, not only in terms of raw material use but also by simplifying the manufacturing process, allowing for a more homogenous material composition and improved structural integrity. Additionally, the capillary casting method does not require the extensive and expensive infrastructure associated with the production of PV cells. As such, the upfront investment and operational expenses for setting up TEG manufacturing are just a fraction of those required for PV cell facilities.

[0035] In at least some embodiments and as described further below, the present disclosure describes a method for manufacturing a p/n junction for a TEG. A conductive substrate is sandwiched between a pair of barriers prior to casting. The substrate comprises a mold delineated by a periphery of the substrate, thereby providing access to the interior of the mold through a gate in the substrate’s edge. While the substrate is sandwiched, at least part of the mold is submerged into a molten alloy that is at a higher temperature than the substrate. The molten alloy is tellurium-based (i.e., by weight, tellurium is the heaviest constituent of the alloy) and, by virtue of the temperature differential across the substrate and the molten alloy, submerging the mold results in the molten alloy being drawn into the mold by capillary action. The substrate is then removed from the molten alloy, allowing it to cool and thus solidifying the molten alloy. Depending on the material selection used, the conductive substrate acts as one of a negatively or positively doped material of the p/n junction and the solidified alloy acts as the other of the negatively or positively doped material of the p/n junction.

[0036] The conductive substrate that is submerged may comprise multiple segments that are spaced apart from each other. In this case, the molds formed in the segments may be shaped such that the resulting one or more casts are formed between respective one or more pairs of those segments, with each of those casts interlocking a respective one of the one or more pairs together. In this way, soldering to connect the segments together may be avoided, thus saving on labor and resulting in a more mechanically robust TEG.

[0037] Referring now to FIGS. 1A and IB, there are shown front elevation and perspective views, respectively, of a conductive substrate 102 for use in manufacturing a series of thermoelectric p/n junctions, according to an example embodiment. In the depicted embodiment the substrate 102 is copper, although in other embodiments the substrate 102 may be manufactured using another metal or an alloy, as described further below. The substrate 102 comprises a series of segments 103 spaced apart from each other. The segments 103 are longitudinally aligned with each other, and each of the segments 103 comprises a pair of molds 104 on opposing sides of the segment 103. Each of the molds 104 is accessible from outside of the segment 103 via respective gates 106 in the segment 103. The segment’s 103 periphery delineates the mold 104; consequently, and as described further below, liquid such as molten metal can enter the molds 104 longitudinally across the left and right ends of the segments 103 even if the front and rear sides of the segments 103 are sealed. The substrate 102 may be manufactured by precision cutting a copper sheet with the desired thickness into the desired shape, such as that depicted in FIGS. 1A and IB.

[0038] FIGS. 2A and 2B respectively show how the conductive substrate of FIGS. 1A and IB is sandwiched between first and second barriers 202a, b as part of the process for manufacturing the series of p/n junctions, according to an example embodiment. The barriers 202a, b in the depicted embodiment are pure alumina ceramic sheets, although in at least some other embodiments they may simply be ceramic sheets or sheets manufactured using another electrically non-conductive/insulative material. FIG. 2A in particular shows the barriers 202a,b being brought down to respectively cover the front and rear sides of the substrate 102 to sandwich the substrate 102, while FIG. 2B depicts an end view of the substrate 102 and barriers 202a, b when the substrate 102 is sandwiched by the barriers 202a, b. The sandwiched substrate 102 is secured together, such as by using a clamp, to ensure proper alignment and stability.

[0039] FIG. 3 shows how the sandwiched conductive substrate 102 of FIG. 2B is submerged into and then removed from a molten alloy 304 in order to cast the series of thermoelectric p/n junctions using capillary casting, according to an example embodiment. More particularly, the sandwiched substrate 102 is lowered into the molten alloy 304 at time ti to a depth corresponding to an immersion line 302 that corresponds to at least part of the gate 106 being submerged in the molten alloy 304. This puts the gates 106 in direct contact with the molten alloy 304. While submerged, and as a result of the temperature differential between the cooler sandwiched substrate 102 and the hot molten alloy 304, the molten alloy 304 is drawn into the molds 104 through their respective gates 106, and also into the space between neighboring segments 103, by capillary action.

[0040] The molten alloy 304 is tellurium-based and may comprise any one or more of several additional components. For example, the molten alloy 304 may further comprise any one or more of antimony, to provide structural stability to the molten alloy 304 once it has solidified; bismuth, which enables a slight expansion of the solidified alloy relative to the molten alloy 304 to help there be a tight fit between the solidified alloy and the substrate 102; and glass powder, such as micron-sized (or smaller) glass power, which facilitates good adhesion of the solidified alloy to the substrate 102. By “micron-sized” or smaller, it is meant a glass powder whose constituent particles have diameters of one micron or smaller. In particular, use of glass powder is counterintuitive because glass is an insulator, but experimentally it has been found that adding an appropriate amount of glass powder promotes favorable mechanical qualities (i.e., adhesion) without overly prejudicing electrical conductivity. Various combinations of the above components may be used to make the molten alloy 304. For example, bismuth in particular may be excluded from the molten alloy 304; more generally, the molten alloy 304 may comprise tellurium with any one or more of the antimony, bismuth, and glass powder. An example molten alloy 304 may comprise 3 parts of the tellurium, 1.5 parts of the antimony, and 0.1 parts of the micron-sized glass powder, for example, and optionally also comprise 0.5 parts of the bismuth.

[0041] Once the molds 104 are filled, the sandwiched substrate 102 is removed from the molten alloy 304 at time t2. Typically, the difference between times ti and t2 may be less than 1 second. The molten alloy 304 cools once the sandwiched substrate 102 is removed, following which the barriers 202a, b are removed. The barriers 202a, b are made with an inert material (i.e., a material that does not physically or chemically bond with the alloy in its molten or solidified states or with the substrate 102), and they may accordingly be removed relatively easily by simply physically pulling the barriers 202a, b away from the substrate 102. If there is some adhesion (e.g., by virtue of there being some bonding between the barriers 202a, b and the alloy 304), a releasing agent such as boron nitride spray may be used to help the barriers 202a, b release from the combined substrate 102 and solidified alloy. The resulting solidified alloy is a homogenous alloy mix, with reduced susceptibility to cracking and environmental hazards associated with conventional powder metallurgy (e.g., sintering).

[0042] FIGS. 4A and 4B are front elevation and perspective views, respectively, of a TEG 402 comprising a series of thermoelectric p/n junctions 406 that results from the capillary casting of FIG. 3. Each of the p/n junctions 406 is a “thermoelectric module” across which a voltage is generated in response to a heat differential spanning the junction 406.

[0043] More particularly, by virtue of the capillary action described above drawing the molten alloy 304 into the molds 104 and the spaces between segments 103, the disconnected segments 103 of FIGS. 1A and IB have been secured together by virtue of the now solidified alloy 404 interlocking the segments 103 together. In the depicted embodiment, the width of the gate 106 is less than a maximum width of the mold 104; more particularly, in the depicted embodiment in which the mold 104 is circular, the width of the gate 106 is less than the diameter of the mold 104. The results in a puzzle-like interlocking connection of the various segments 103. While a particular type of interlocking connection is depicted in FIGS. 4A and 4B, other interlocking shapes are possible, such as described below in respect of FIGS. 5 A and 5B. The interlocking of the segments 103 using the solidified alloy 404 promotes not only the TEG’s 402 structural stability, but also electrical continuity.

[0044] In FIGS. 4A and 4B in which the substrate 102 is copper and the solidified alloy 404 comprises 3 parts tellurium, 1.5 parts antimony, 0.5 parts bismuth, and 0. 1 parts of micronsized glass powder, the substrate 102 acts as the negatively doped material of the p/n junction 406 and the solidified alloy 404 acts as the positively doped material of the p/n junction 406. However, in at least some other embodiments, the substrate 102 may act as the positively doped material and the solidified alloy 404 may act as the negatively doped material. For example, in embodiments in which the substrate 102 is antimony telluride or bismuth telluride instead of copper, the substrate 102 may act as the positively doped material.

[0045] The TEG 402 of FIGS. 4A and 4B accordingly comprises several thermoelectric modules in the form of p/n junctions 406 electrically connected in series. In response to heat being applied across the modules, each of the modules generates a voltage, and collectively the voltages generated by the modules of the TEG 402 are summed as they are electrically connected in series. For example, for a TEG 402 comprising an approximately 100 mm x 50 mm array of series-connected p/n junctions 406 approximately 4 mm long each was able to generate approximately 5 W of power.

[0046] FIG. 6 shows an array 600 of TEGs 402 manufactured through repeatedly performing the capillary casting of FIG. 3, according to an example embodiment. Any one of the TEGs 402 may be connected in series or parallel (not shown) with any other of the TEGs 402, thereby facilitating flexibility in power generation.

[0047] As mentioned above, while the embodiments of FIGS. 1A through 4B depict a coplanar substrate 102 and barriers 202a, b, other shapes and configurations are possible. For example, FIG. 5 A is a perspective view of another embodiment of the conductive substrate 102 for use in a stacked tubular configuration as shown in the left-hand side of FIG. 5B. As with the substrate 102 of FIGS. 1A through 4B, the substrate 102 for the tubular embodiment of FIG. 5A comprises molds 104 and corresponding gates 106 delineated by the substrate’s 102 periphery 108. The substrate 102 is generally cylindrical and comprises one set of two molds 104 spaced 180 degrees apart from each other on one edge and another set of two molds 104 spaced 180 degrees apart from each other on an opposing edge, with the two sets of molds offset 90 degrees from each other. These substrates 102 may be spaced apart from each other and stacked edge-to-edge as shown in the left-hand side of FIG. 5B, in a configuration analogous to that shown in the planar embodiment of FIG. 1A.

[0048] The right-hand side of FIG. 5B shows tubular barriers 202a, b for use in sandwiching the series of conductive substrates 102 on the left-hand side of FIG. 5B as part of performing capillary casting, according to an example embodiment. In FIG. 5B, during capillary casting the first barrier 202a extends over the outside of the exterior curved surface of the stack of FIG. 5B and the second barrier 202b extends within the interior curved surface of the stack of FIG. 5B, thereby sandwiching the substrates 102. In the embodiment of FIGS. 5 A and 5B, the barriers 202a, b are also coaxial with the stack of substrates 102 when the substrates 102 are sandwiched. The first barrier 202a comprises a series of holes 502 through which the molten alloy 304 may be drawn into the substrate’ s 102 molds 106 by capillary action when the sandwiched substrate 102 is submerged in the molten alloy 304. The holes 502 are spaced interstitially between the substrate segments 103 when they are sandwiched by the barriers 202a, b; this permits the molten alloy 304 to be drawn in the spaces between the segments 103 and into the molds 106 of respective neighboring segments 103 when submerged in the molten alloy 304. While these holes 502 are shown in the first barrier 202a in FIG. 5B, in at least some other embodiments (not shown) the holes 502 may additionally or alternatively be present in the second barrier 202b. The sandwiched substrates 102 may then be submerged in the molten alloy 304 and subsequently removed as described above in respect of the coplanar embodiment to form a TEG.

Example Use Cases

[0049] Despite lower efficiency compared to photovoltaic panels, thermoelectric panels manufactured using the capillary casting method as described above are effective in scenarios with limited sunlight exposure, partial shading, or restricted installation spaces. These panels can function under a variety of environmental conditions, providing a consistent power generation solution based on heat differential that is not dependent on sunlight.

[0050] One example application for the TEG 402 is the recovery of waste heat from automotive radiator systems. Internal combustion engine (ICE) vehicles generate significant amounts of thermal energy, much of which is not utilized for propulsion and is dissipated as waste heat. By integrating the thermoelectric modules into the vehicle's radiator system, where the coolant fluid captures engine heat, this waste heat can be converted into electrical energy. An example implementation of this is depicted in FIG. 7, which shows the array 600 of TEGs 402 of FIG. 6 used to generate electricity in combination with a heat source 702 and heat sink 704. For the sake of clarity of illustration, the electrical connections to and within the array 600 are not depicted, nor is a frame that may be used to encase and protect the array 600 and ensure good thermal contact with both the heat source 702 and heat sink 704.

[0051] In FIG. 6, the array 600 is positioned such that one side interfaces with the hot coolant fluid exiting the engine, which is the heat source 702, while the opposite side is exposed to the ambient temperature or a secondary cooling mechanism, which in FIG. 6 is a heat sink 704. The temperature differential across the thermoelectric modules induces a voltage via the Seebeck effect, generating electricity that can be used to power vehicle electronics, charge batteries, or support other onboard systems. This process effectively recaptures energy that would otherwise be lost, enhancing the overall energy efficiency of the vehicle without the need for external energy inputs or increasing operational complexity.

[0052] The modular design of the TEG 402 allows for easy integration into existing vehicle designs, with the potential for retrofitting into current fleets as well as incorporation into new vehicle manufacturing. Integration into vehicles not only contributes to the reduction of fuel consumption by offloading the electrical generation duties from the alternator but also aligns with efforts to increase energy efficiency and reduce the carbon footprint of automotive transportation.

[0053] It should be understood that various modifications, alterations, and adaptations may be made to the specific elements and configurations disclosed, including but not limited to dimensions, materials, positions, and operational mechanisms, without departing from the essence and scope of the disclosure.

[0054] The terminology used herein is only for the purpose of describing particular embodiments and is not intended to be limiting. Accordingly, as used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and “comprising”, when used in this specification, specify the presence of one or more stated features, integers, steps, operations, elements, and components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and groups. Directional terms such as “top”, “bottom”, “upwards”, “downwards”, “vertically”, and “laterally” are used in the following description for the purpose of providing relative reference only, and are not intended to suggest any limitations on how any article is to be positioned during use, or to be mounted in an assembly or relative to an environment. Additionally, the term “connect” and variants of it such as “connected”, “connects”, and “connecting” as used in this description are intended to include indirect and direct connections unless otherwise indicated. For example, if a first device is connected to a second device, that coupling may be through a direct connection or through an indirect connection via other devices and connections. Similarly, if the first device is communicatively connected to the second device, communication may be through a direct connection or through an indirect connection via other devices and connections.

[0055] Directional terms such as “top,” “bottom,” “upwards,” “downwards,” “vertically,” and “laterally” are used in the following description for the purpose of providing relative reference only, and are not intended to suggest any limitations on how any article is to be positioned during use, or to be mounted in an assembly or relative to an environment.

[0056] Use of language such as “at least one of X, Y, and Z,” “at least one of X, Y, or Z,” “at least one or more of X, Y, and Z,” “at least one or more of X, Y, and/or Z,” or “at least one of X, Y, and/or Z,” is intended to be inclusive of both a single item (e.g., just X, or just Y, or just Z) and multiple items (e.g., {X and Y}, {X and Z}, {Y and Z}, or {X, Y, and Z}). The phrase “at least one of’ and similar phrases are not intended to convey a requirement that each possible item must be present, although each possible item may be present.

[0057] It is contemplated that any part of any aspect or embodiment discussed in this specification can be implemented or combined with any part of any other aspect or embodiment discussed in this specification, so long as such those parts are not mutually exclusive with each other.

[0058] While every effort has been made to provide a detailed and accurate description of the disclosure herein, it should be noted that the scope of the disclosure is not limited to the exact configurations and embodiments described. The description provided is intended to illustrate the principles of the disclosure and not to limit the disclosure to the specific embodiments illustrated. It is intended that the scope of the disclosure be defined by the appended claims, their equivalents, and their potential applications in other fields.

Claims

1. A method for manufacturing a p/n junction for a thermoelectric generator, the method comprising: sandwiching a conductive substrate between a pair of inert barriers, wherein the conductive substrate comprises a mold delineated by a periphery of the substrate; while the substrate is sandwiched, submerging at least part of the mold into a tellurium-based molten alloy at a higher temperature than the substrate, wherein submerging the mold into the molten alloy results in the molten alloy being drawn into the mold by capillary action; and solidifying the molten alloy by removing the substrate from the molten alloy, wherein the conductive substrate acts as one of a negatively or positively doped material of the p/n junction and the solidified alloy acts as the other of the negatively or positively doped material of the p/n junction.

2. The method of claim 1, wherein the conductive substrate acts as the positively doped material and the solidified alloy acts as the negatively doped material.

3. The method of claim 1, wherein the conductive substrate acts as the negatively doped material and the solidified alloy acts as the positively doped material.

4. The method of claim 3, wherein the conductive substrate is copper.

5. The method of any one of claims 1 to 4, wherein the pair of barriers is ceramic.

6. The method of claim 5, wherein the ceramic is alumina ceramic.

7. The method of any one of claims 1 to 6, wherein the barriers and the conductive substrate are coplanar with each other.

8. The method of any one of claims 1 to 6, wherein the conductive substrate and the barriers are tubular, and wherein the barriers respectively extend within and outside of the conductive substrate.

9. The method of any one of claims 1 to 8, wherein the molten alloy further comprises antimony.

10. The method of any one of claims 1 to 10, wherein the molten alloy further comprises micron-sized or smaller glass powder.

11. The method of claim 10, wherein the molten alloy comprises 3 parts of the tellurium, 1.5 parts of the antimony, and 0.1 parts of the micron-sized glass powder.

12. The method of any one of claims 1 to 10, wherein the molten alloy further comprises bismuth.

13. The method of claim 10, wherein the molten alloy comprises 3 parts of the tellurium, 1.5 parts of the antimony, 0.5 parts of the bismuth, and 0.1 parts of the micron-sized glass powder.

14. The method of any one of claims 1 to 13, wherein: prior to the submerging, the substrate comprises multiple segments that are disconnected; during the submerging, the molten alloy is also drawn between the segments; and the mold is shaped such that after the solidifying, the segments are secured together by virtue of the solidified alloy interlocking the segments together.

15. The method of claim 14, wherein during the submerging the molten alloy enters the mold through a gate, and wherein a width of the gate is less than a maximum width of the mold.

16. At least one p/n junction for a thermoelectric generator, the at least one junction comprising: a conductive substrate comprising multiple segments spaced apart from each other; and one or more casts of a tellurium-based alloy between respective one or more pairs of segments, wherein each of the one or more casts interlocks a respective one of the one or more pairs of segments together, and wherein the conductive substrate acts as one of a negatively or positively doped material of the p/n junction and the solidified alloy acts as the other of the negatively or positively doped material of the p/n junction.

17. The at least one p/n junction of claim 16, wherein the conductive substrate is copper.

18. The at least one p/n junction of claim 16 or 17, wherein the alloy comprises 3 parts tellurium, 1.5 parts antimony, 0.5 parts bismuth, and 0.1 parts micron-sized glass powder.

19. The at least one p/n junction of any one of claims 16 to 18, wherein the conductive substrate is tubular.

20. The at least one p/n junction of any one of claims 16 to 19, wherein each of the multiple segments comprises a mold and a gate that contain a portion of one of the one or more casts, wherein a width of the gate is less than a maximum width of the mold.