2019/12/06 by Jun Peng, Ian T. Witting, Nicholas R. Geisendorfer +8 · 1 citation
Materials Science · Engineering · #Advanced Thermoelectric Materials and Devices #Innovative Energy Harvesting Technologies #Thermal properties of materials #Thermoelectric effect #Materials science #Seebeck coefficient #Energy harvesting #Thermoelectric materials #Thermoelectric generator #Thermal conductivity #Composite material #Extrusion #Percolation theory #Engineering physics #Conductivity #Optoelectronics #Power (physics) #Physics #Thermodynamics
paper · pdf · doi:10.1038/s41467-019-13461-2
openalex publication_date 2019/12/06 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
Abstract Whereas the rigid nature of standard thermoelectrics limits their use, flexible thermoelectric platforms can find much broader applications, for example, in low-power, wearable energy harvesting for internet-of-things applications. Here we realize continuous, flexible thermoelectric threads via a rapid extrusion of 3D-printable composite inks (Bi 2 Te 3 n- or p- type micrograins within a non-conducting polymer as a binder) followed by compression through a roller-pair, and we demonstrate their applications in flexible, low-power energy harvesting. The thermoelectric power factors of these threads are enhanced up to 7 orders-of-magnitude after lateral compression, principally due to improved conductivity resulting from reduced void volume fraction and partial alignment of thermoelectric micrograins. This dependence is quantified using a conductivity/Seebeck vise for pressure-controlled studies. The resulting grain-to-grain conductivity is well explained with a modified percolation theory to model a pressure-dependent conductivity. Flexible thermoelectric modules are demonstrated to utilize thermal gradients either parallel or transverse to the thread direction.