Enhanced self-polarization effect by tuning interfacial binding energy for self-powered flexible piezoelectric pressure sensors

Flexible pressure sensors based on PVDF and its copolymers have been extensively investigated due to their unique self-powered characteristics and high sensitivity. Herein, a new strategy of manipulation the interfacial binding energy between the organic and inorganic groups has been utilized to enhance the performance of the flexible piezoelectric pressure sensors. Four types of interfacial interactions of different binding energy have been designed in the polydopamine (PDA) decorated lead zirconate titanate (PZT) and P(VDF-TrFE) composites. The results based on first-principles calculations reveal that PDA acts as a binder between PZT and P(VDF-TrFE) due to the strong interaction between -NH2 and -CF2- dipoles. The strong interaction results in enhanced self-polarization effect and enhanced piezoelectric effect, and the improved sensitivity of the pressure sensors. The β-phase content of P(VDF-TrFE) increases from 17% to 87% when the content of PZT@PDA nanoparticles reaches 15wt%. PZT@PDA/P(VDF-TrFE) self-powered pressure sensor (SPPS) exhibits an output voltage of 44V and a high sensitivity of 1.38V/kPa with no significant performance degradation during 10,000 cycles of pressure application. Moreover, the SPPS shows an excellent self-powered ability with the highest short-circuit current of 8.6 μA and the peak power density of 15 μW/cm2. The SPPS demonstrates the extraordinary sensing performance in body motion sensing and hand gesture recognition.