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

Abstract The emerging fields of wearables and the Internet of Things introduce the need for electronics and power sources with unconventional form factors: large area, customizable shape, and flexibility. Thermoelectric (TE) generators can power those systems by converting abundant waste heat into electricity, whereas the versatility of additive manufacturing suits heterogeneous form factors. Here, additive manufacturing of high‐performing flexible TEs 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 simultaneous 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 TEs of 0.4 Ω sq −1 are achieved, leading to unprecedented potential for power generation. This versatile fabrication route enables innovative implementations, such as cuttable arrays adapting to specific applications in self‐powered sensing, and energy harvesting from unusual scenarios like human skin and curved hot surfaces.