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

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 Bi₂Te_2.7Se_0.3 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.