Improved piezoelectric and conductive properties of bent-core liquid crystal-polymer composites for sustainable energy harvesting

Organic piezoelectric polymer materials have recently garnered substantial interest owing to their potential applications in sustainable as well as renewable energy sources for small-power electronics. In the present work, a novel bent-core liquid crystal (BCLC) (6-F-OH) is infused with the polyvinylidene fluoride (PVDF) host that demonstrates an augmented piezoelectric performance with an elevated electrical conductivity. A simple yet cost-effective fabrication process is employed to achieve high-efficiency piezoelectric polymer composite free-standing films with improved flexibility for future-ready wearable device applications. A comprehensive investigation of the role of BCLCs in promoting the electroactive polar β-phase within the host polymer is conducted. The energy harvesting performances were evaluated at varying frequencies for the optimization of the BCLC-infused composite-based piezoelectric devices. The result reveals a maximum piezoelectric performance at 3 wt.% concentration of BCLC producing an output open-circuit voltage (V_OC) of ≈ 25 V_PP and short circuit current (I_SC) of ≈ 700 nA, a multi-fold enhancement as compared to pristine PVDF-based devices. Moreover, the composite film with 3 wt.% BCLC/PVDF demonstrates the highest remnant polarization and dielectric constant value among all the samples. The effective rise in the electrical conductivity of the BCLC-infused composite at an optimized weight fraction over its pristine PVDF counterpart is also discussed based on the percolative pathways produced by the BCLCs at the interfaces of the composite domains. Finally, some of the applications of the devised organic energy harvesters are demonstrated. The proposed integration of such LCs with the PVDF opens a unique pathway towards an all-organic polymer composite-based energy harvesting device for self-powered device applications.