Embedded Direct‐Written Organic Micro‐TEGs for High‐Efficiency Skin‐Heat Harvesting

ABSTRACT Flexible thermoelectric generators (TEGs) are transforming wearable electronics by harvesting body heat as a sustainable power source, offering an alternative to conventional energy systems. However, their performance is often constrained by low thermal‐to‐electrical conversion efficiency. This work presents a detailed numerical investigation, based on finite element analysis (FEA), to optimize direct‐written organic micro‐TEGs (µ‐OTEGs) embedded in flexible substrates for enhanced skin‐heat energy harvesting. Organic semiconductors, including p ‐type poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and n ‐type poly(benzodifurandione)/benzodipyrandione (PBFDO/BPDO), were selected for their tunable electrical and mechanical properties. Key design parameters were systematically refined to maximize power density and conversion efficiency. The embedded structure effectively minimizes interfacial heat loss, ensuring stable performance across various body locations and thermal conditions. Under optimized conditions, the embedded‐leg µ‐OTEG increases the temperature gradient (ΔT) from 3.58 to 10.4°C, raises the open‐circuit voltage ( V OC ) from 10.41 to 18.4 mV, and boosts the output power from 0.83 to 2.56 µW. Remarkably, the proposed architecture achieves over a 250% enhancement in thermal efficiency compared with conventional wearable TEGs, attributed to the optimized embedded configuration. These findings highlight the potential of direct‐written organic TEGs as scalable, self‐powered platforms for next‐generation wearable and biomedical devices.