Solution Synthesis and Additive Manufacturing of Bismuth Telluride Nanoflakes for Flexible Energy Harvesting

Flexible thermoelectric generators (TEGs) are energy harvesting devices which convert temperature differences into electrical power. These devices require no moving parts and offer silent and autonomous operation. The variety of suitable materials covering a broad range of operating temperatures positions TEGs as a promising renewable energy source using waste heat recovery, especially for space and microgravity applications. Conventional manufacturing of flexible electronic and thermoelectric devices requires complicated and relatively expensive processing, which limits the capabilities of in-space manufacturing. Additive manufacturing (AM) expands the use of flexible electronics to new surfaces, applications, and recently, low gravity conditions. Plasma jet printing (PJP) is a new AM modality in which material is deposited via a gravity- independent plasma. This thesis demonstrates solution processing, ink synthesis, and PJP of bismuth telluride (Bi2Te3) nanoflakes for low temperature energy harvesting. Synthesis conditions were tailored to control nanoflake morphology and ink processing was optimized for direct printing on flexible polyimide substrates. The thermoelectric films demonstrate promising thermoelectric properties, material adhesion, and flexibility, with only a 7.2% variation in performance after 10,000 bending cycles over a 16 mm radius of curvature. This advancement of Bi2Te3 solution processing and demonstration of PJP of thermoelectric films marks a significant contribution to in space manufacturing of flexible thermoelectric devices for wearable technology and low temperature energy harvesting