Abstract

The increasing demand for lightweight, flexible, wearable, and self-powered electronic systems has stimulated extensive research on polymer-based energy-harvesting materials. Conventional inorganic piezoelectric ceramics exhibit high electromechanical performance but are generally rigid, brittle and unsuitable for conformal or wearable applications. Flexible electroactive polymers, particularly poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE)], provide an attractive alternative because of their flexibility, low density, chemical stability, processability and inherent piezoelectric properties. Kawai (1969), [1], established the fundamental piezoelectric behavior of PVDF, initiating extensive research into electroactive polymeric materials. Subsequent developments have focused on increasing the electroactive β-phase, controlling molecular orientation, introducing nanofillers, engineering interfaces and designing hierarchical device structures.This paper presents a focused study of flexible polymer-based energy harvesting systems, emphasising piezoelectric, triboelectric and hybrid mechanisms. It discusses the influence of polymer phase structure, fabrication technique, nanofiller incorporation, ceramic–polymer interfaces, and device architecture. Representative systems based on ZnO/PVDF, graphene/PVDF, KNN/PVDF, BaTiO?/PVDF, BaTiO?/P(VDF-TrFE) and related composites demonstrate the potential of polymer-based materials for mechanical-energy conversion. Recent approaches involving electrospinning, surface engineering, interfacial modification, nanostructuring and hybrid piezoelectric–triboelectric operation are also examined. Finally, the major challenges related to output reproducibility, standardization, long-term stability, energy-storage integration and practical scalability are identified.