Tuning the space charge polarization of PVDF based ternary composite for piezo-tribo hybrid energy harvesting

Abstract

Enhancement in the output performance of triboelectric nanogenerators by using different suitable techniques is of tremendous interest among researchers. Here, we propose an easy and cost-effective technique to improve the output performance of the rarely explored poly(vinylidene fluoride) (PVDF) based piezo-tribo hybrid nanogenerators. The space charge polarization of the PVDF based composites has been tuned here by forming a PVDF/0.5(Ba0.7Ca0.3)TiO3-0.5Ba(Ti0.8Zr0.2)O3 (BCZT)/Multi-Walled Carbon Nanotube (MWCNT) based ternary composite. Along with the improved piezoelectricity of PVDF-BCZT based binary composites, the addition of a third MWCNT phase has helped in significantly improving the space charge polarization. The ac conductivity is increased to 5.29 × 10-12 and 1.23 × 10-11 ω-1 cm-1 for the binary and ternary composites, respectively, from a value of 7.64 × 10-13 ω-1 cm-1 (at 1 kHz) for neat PVDF. This improved conducting pathway formed by the increased space charge polarization has supported the easy transportation of mobile charge carriers within the composite film and film to the electrode, which has augmented the overall output piezo-tribo hybrid energy harvesting performance of the device. An ultrahigh output power density of ∼150 μW/cm2 has been achieved for the said ternary system, which suppresses the value of output power density of the other similar kind of devices fabricated via a similar technique. The applicability of this device has been further demonstrated by using it in powering up small electronic devices and in different sensing and energy harvesting applications. Thus, the device, after further tuning of its dimension, may be applied as a power source in various low-power-consuming portable electronic systems and self-powered sensing devices.