Rapid, localized heat management is important for electronic devices and will have applications starting from wearable materials to burn treatment. While so-called thermoelectric materials convert temperature differences to electrical voltage and vice versa, their efficiency is usually limited, and their production is dear and wasteful. In a brand new paper published in Science, researchers from the Institute of Science and Technology Austria (ISTA) used a 3D printing technique to fabricate high-performance thermoelectric materials, reducing production costs significantly.
Thermoelectric coolers, also called solid-state fridges, can induce localized cooling by utilizing an electrical current to transfer heat from one side of the device to a different. Their long lifetimes, invulnerability to leaks, size and shape tunability, and the shortage of moving parts (corresponding to circulating liquids) make these devices ideal for diverse cooling applications, corresponding to electronics. Nevertheless, manufacturing them out of ingots is related to high costs and generates plenty of material waste. As well as, the devices’ performance stays limited.
Now, a team on the Institute of Science and Technology Austria (ISTA), led by Verbund Professor for Energy Sciences and Head of the Werner Siemens Thermoelectric Laboratory Maria Ibáñez, with first creator and ISTA postdoc Shengduo Xu, developed high-performance thermoelectric materials out of the 3D printer and used them to construct a thermoelectric cooler. “Our modern integration of 3D printing into thermoelectric cooler fabrication greatly improves manufacturing efficiency and reduces costs,” says Xu. Also, in contrast to previous attempts at 3D printing thermoelectric materials, the current method yields materials with considerably higher performance. ISTA Professor Ibáñez adds, “With commercial-level performance, our work has the potential to increase beyond academia, holding practical relevance and attracting interest from industries in search of real-world applications.”
Pushing the boundaries of thermoelectric technologies
While all materials display some thermoelectric effect, it is usually too negligible to be useful. Materials exhibiting a high enough thermoelectric effect are frequently so-called “degenerate semiconductors,” i.e., “doped” semiconductors, to which impurities are introduced intentionally in order that they behave like conductors. Current state-of-the-art thermoelectric coolers are produced using ingot-based manufacturing techniques — expensive and power-hungry procedures requiring extensive machining processes after production, where lots of material is wasted. “With our present work, we will 3D print precisely the needed shape of thermoelectric materials. As well as, the resulting devices exhibit a net cooling effect of fifty degrees within the air. Which means our 3D-printed materials perform similarly to ones which can be significantly costlier to fabricate,” says Xu. Thus, the team of ISTA material scientists proposes a scalable and cost-effective production method for thermoelectric materials, circumventing energy-intensive and time-consuming steps.
Printed materials with optimized particle bonding
Beyond applying 3D printing techniques to supply thermoelectric materials, the team designed the inks in order that, because the carrier solvent evaporates, effective and robust atomic bonds are formed between grains, creating an atomically connected material network. Because of this, the interfacial chemical bonds improve the charge transfer between grains. This explains how the team managed to boost the thermoelectric performance of their 3D-printed materials while also shedding latest light on the transport properties of porous materials. “We employed an extrusion-based 3D printing technique and designed the ink formulation to make sure the integrity of the printed structure and boost particle bonding. This allowed us to supply the primary thermoelectric coolers from printed materials with comparable performance to ingot-based devices while saving material and energy,” says Ibáñez.
Medical applications, energy harvesting, and sustainability
Beyond rapid heat management in electronics and wearable devices, thermoelectric coolers could have medical applications, including burn treatment and muscle strain relief. As well as, the ink formulation method developed by the team of ISTA scientists will be adapted for other materials to be utilized in high-temperature thermoelectric generators — devices that may generate electrical voltage from a temperature difference. In response to the team, such an approach could broaden the applicability of thermoelectric generators across various waste energy harvesting systems.
“We successfully executed a full-cycle approach, from optimizing the raw materials’ thermoelectric performance to fabricating a stable, high-performance end-product,” says Ibáñez. Xu adds, “Our work offers a transformative solution for thermoelectric device production and heralds a brand new era of efficient and sustainable thermoelectric technologies.”
