Increased effective piezoelectric response of structurally modulated P(VDF-TrFE) film devices for effective energy harvesters

The low piezoelectric response (piezoelectric coefficient d33 lower than 30 pC N−1) of PVDF-based polymers limits their practical applications. Here we report a mechanical structure which can enhance the effective piezoelectric response of P(VDF-TrFE) copolymer. The polymer films were fabricated into a circular arch structure or arrays of arch structures. When a plane force was applied to the arch films, the force is concentrated at the outer rim of the arch structure. The effective piezoelectric response can be enhanced by >70 times because of the stress concentration and the measured effective piezoelectric response can be as high as 1990 pC N−1. The arch films exhibit an enhanced energy harvesting performance when they are utilized as mechanical energy harvesting devices. The output power density was improved by >2700 times compared with that measured in the films without arch structure. An output power density of 9 mW cm−3 was achieved in the arch films under non-resonance frequency. These results indicate that the proposed polymer-based structure is promising for the practical applications in high-performance flexible piezoelectric devices.