Facile Fabrication of Flexible and High-Performing Thermoelectrics by Direct Laser Printing on Plastic Foil.

The emerging fields of wearables and the Internet of Things introduce the need for electronics and power sources with unconventional form factor: large area, customizable shape and flexibility. Thermoelectric generators can power those systems by converting abundant waste heat into electricity, whereas the versatility of additive manufacturing suits heterogenous form factors. Here, additive manufacturing of high-performing flexible thermoelectrics is proposed. Maskless and large-area patterning of Bi 2 Te 3 -based films is performed by laser powder bed fusion directly on plastic foil. Mechanical interlocking allows simultaneously patterning, sintering and attachment of the films to the substrate without using organic binders that jeopardize the final performance. Material waste could be minimized by recycling the unexposed powder. The particular microstructure of the laser-printed material renders the -otherwise brittle- Bi 2 Te 3 films highly flexible despite their high thickness. The films survive 500 extreme-bending cycles to a 0.76 mm radius. Power factors above 1500 μW m -1 K -2 and a record-low sheet resistance for flexible thermoelectrics of 0.4 Ω/sq are achieved, leading to unprecedented potential for power generation. Our versatile fabrication route enables innovative implementations such as cuttable arrays to adapt device layout to specific applications like self-powered sensing and energy harvesting from unusual scenarios like human skin and curved hot surfaces. This article is protected by copyright. All rights reserved.