Laser Powder Bed Fusion of Bismuth Telluride on Plastic Foil as a Simple Route for The Scalable Fabrication of Flexible and Large-Area Thermoelectric Generators

Thermoelectric generators (TEGs) are solid-state devices that convert waste heat into electrical energy. Conventional manufacturing methods struggle to meet the requirements of scalability and compatibility with unconventional form factors required for emerging applications such as wearables and large-area electronics. In contrast, additive manufacturing techniques offer scalability, reduced material waste, and the ability to conform to various shapes, expanding their potential applications. In particular, Laser Powder Bed Fusion has shown tremendous potential to manufacture high-performing pellets with laser-tunable nanostructure. However, the compatibility with flexible substrate and large-area patterning remains to be demonstrated.<br/>Our work demonstrated the additive manufacturing of high-performing inorganic flexible TEGs by laser powder bed fusion directly onto flexible polyimide foil. We achieve maskless and large-area patterning of thick films of Bi2Te3-based materials deposited from a slurry. By reusing the unexposed powder we minimize material waste. Mechanical interlocking enables simultaneous patterning, sintering, and attachment of films to the flexible substrate, enabling the creation of a highly flexible device adaptable to different shapes.<br/>Moreover, the material structure and chemical composition, and the associated performance, can be precisely tuned by the laser power and scanning speed. For instance the unique microstructure of the laser-printed material imparts remarkable flexibility to the typically brittle Bi2Te3 thick films. Samples can withstand extreme bending with a radius of curvature as small as 0.75 mm while experiencing minimal changes in performance over a 10 mm bending radius. Additionally, we can simultaneously modify the stoichiometry of the material to optimize its power factor. This innovative approach holds promise for the advancement of flexible TEGs and their diverse applications.