High-performance Stretchable Organic Thermoelectric Generator via Rational Thermal Interface Design for Wearable Electronics

Compliant thermoelectric generators (TEGs) hold great promise in the field of self-powered wearable electronics. Yet, the low heat transfer efficiency arising from large thermal resistance between elastic encapsulating materials and the contacted objects severely lowers the thermopower. This issue is much more challenging for organic TEG (oTEG) due to the high parasitic heat loss in the whole polymer system. Herein, guided by finite element analyses, a polydimethylsiloxane based composite coated with Cu is developed as a thermal interface without compromising the compliance of the oTEG, which possesses the merits of high thermal conductivity and significantly reduced thermal resistance, thus maximizing the temperature difference utilization ratio to 86%, which is 75.5% higher than for a routine oTEG. As a proof-of-concept, 50 pairs of p/n porous polyurethane/single-wall carbon nanotube TE legs are integrated onto the designed substrate without further encapsulation. Both simulations and experiments on output performance under various thermal conditions are carried out, and show excellent agreement. The in situ output performance tests under various deformation conditions reveal the mechanical robustness of the oTEG. Finally, an oTEG functioning as a body heat harvester and an environment temperature sensor are demonstrated. The outstanding performances unambiguously demonstrate the success of the thermal interface design strategy for promoting oTEGs applied as wearable electronics.