Digital and scalable laser-based fabrication of reusable bismuth telluride thermoelectrics with superior performance...

Thermoelectrics (TEs) convert waste heat into electrical power while enabling on-demand heating and cooling. Those attributes make TEs particularly appealing to satisfy the heterogeneous needs of wearables and the Internet of Things (IoT). However, current TEs are limited in terms of form factor and scalability. To address these limitations, this work demonstrates a scalable, flexible, and potentially reusable thermoelectric platform produced via the laser powder bed fusion (LPBF) of optimized n-type Bi₂Te₃ and p-type Bi_0.5Sb_1.5Te₃ materials. These laser-printed materials exhibited high power factors exceeding 1200 μW m^-1 K^-2, resulting in a figure of merit (zT) greater than 0.2. When integrated into flexible planar devices, an output power of up to 70 μW was achieved at ΔT = 40 K for a footprint area of 8.3 cm². The devices maintained electrical functionality under bending radii as small as 7.5 mm and withstood over 500 bending cycles. Designed for durability and recyclability, devices damaged by extreme bending could be partially reconditioned via hot pressing. Furthermore, the devices were easily disassembled into half-device modules, enabling straightforward separation and potential recovery of the printed materials. The versatility of the devices was demonstrated through the "active cooling fins" implementation, allowing efficient through-plane thermal harvesting on curved surfaces. This configuration could harvest up to 27 μW from the hot water pipe of a real heating system in ambient conditions. Additionally, rapid and reversible Peltier-driven cooling (~3 °C below room temperature within a few seconds) was achieved. This work highlights the potential of digitally manufactured, multifunctional flexible TEs for next-generation energy harvesting and thermal management in IoT nodes and wearable electronics.