Fully flexible thermoelectric and piezoelectric hybrid generator based on a self-assembled multifunctional single composite film

Abstract

Thermoelectric and piezoelectric hybrid generators (TPHGs) are attractive candidates for powering wearable body sensor networks continuously and permanently owing to their excellent access to human-generated energy. Herein, we propose a fully flexible single film-based TPHG comprising n-type Bi2Te2.7Se0.3 particles and poly(vinylidene fluoride-co-trifluoroethylene). The hybrid generator was assembled through simple drop-casting and gravitational settling effect, for the first time. The film layer sedimented with the conductive thermoelectric particles simultaneously served as an electrode and a bottom substrate for piezoelectric energy harvesting. The fabricated device generated outputs of 1 μA and 4 V at a temperature difference of 3 K and a bending displacement of 5 mm; these values indicate that the thermoelectric and piezoelectric effects were combined well without compromising the energy harvesting performance of each part. Furthermore, the fabricated device exhibited robust mechanical durability for ∼5000 bending cycles; this result was better than those of previously reported flexible TPHGs (f-TPHGs). The proposed design concept for f-TPHGs can aid in the development of high-performance multisource energy harvesting devices for wearable sensors.