Inkjet Printing Flexible Thermoelectric Devices Using Metal Chalcogenide Nanowires

Abstract Development of flexible thermoelectric devices offers exciting opportunities for wearable applications in consumer electronics, healthcare, human–machine interface, etc. Despite the increased interests and efforts in nanotechnology‐enabled flexible thermoelectrics, translating the superior properties of thermoelectric materials from nanoscale to macroscale and reducing the manufacturing costs at the device level remain a major challenge. Here, an economic and scalable inkjet printing method is reported to fabricate high‐performance flexible thermoelectric devices. A general templated‐directed chemical transformation process is employed to synthesize several types of 1D metal chalcogenide nanowires (e.g., Ag 2 Te, Cu 7 Te 4 , and Bi 2 Te 2.7 Se 0.3 ). These nanowires are made into inks suitable for inkjet printing by dispersing them in ethanol without any additives. As a showcase for thermoelectric applications, fully inkjet‐printed Ag 2 Te‐based flexible films and devices are prepared. The printed films exhibit a power factor of 493.8 µW m −1 K −2 at 400 K and the printed devices demonstrate a maximum power density of 0.9 µW cm −2 K −2 , both of which are significantly higher than those reported in state‐of‐the‐art inkjet‐printed thermoelectrics. The protocols of metal chalcogenide ink formulations, as well as printing are general and extendable to a wider range of material systems, suggesting the great potential of this printing platform for scalable manufacturing of next‐generation, high‐performance flexible thermoelectric devices.