Scalable solution-processed ferroelectric polymers exhibiting markedly enhanced piezoelectricity.

Intensive efforts have been made to enhance the weak piezoelectric coefficients of ferroelectric polymers for flexible and wearable devices. However, previous approaches are highly dependent on synthesis of desired composition and complex/hash processing conditions while the scalability remains rarely addressed limiting practical applicability. Here we report large piezoelectric coefficient d33 in scalable solution-processed ferroelectric poly(vinylidene fluoride-co-trifluoroethylene) copolymers modified by C=C and C=O double bonds. We reveal that the introduction of C=C double bonds tune the energetic competition between ordered and disordered crystalline conformations. As a result, greatly enhanced d33 of -90.5 pC N-1 and dielectric constant of 22.7 are achieved, corresponding to about 3 times and 2 times as large as that of benchmark poly(vinylidene fluoride). We fabricate flexible and wearable sensors enabling detection of various signals such as pressure and sound with high sensitivity, which find promise in pressure mapping, health monitoring and acoustic sensing applications.