Unlocking β-phase in electrospun PVDF: Nanofiller-induced phase engineering for TENGs

ABSTRACT Triboelectric nanogenerators (TENGs) has emerged as an effective approach for harvesting ambient mechanical energy for powering small electronic devices and self-powered sensing systems. Among various triboelectric materials, poly(vinylidene fluoride) (PVDF) has gained significant attention due to its combined piezoelectric and ferroelectric properties, which are strongly governed by its crystalline phase. In particular, the electroactive β -phase plays a crucial role in enhancing charge generation and improving device performance. However, the dominance of non-polar α -phase in conventionally processed PVDF remains a major limitation for achieving high triboelectric output. Recent efforts have focused on inducing β -phase formation through advanced processing techniques and material modifications. Among these, electrospinning have emerged as a powerful strategy for promoting dipole alignment and tailoring fiber morphology, thereby facilitating enhanced electroactive phase formation. In addition, the incorporation of functional nanofillers including metal oxides, carbon-based nanomaterials (NMs), and polymer blends have shown significant influence on phase transformation, dielectric properties, and charge trapping behavior of PVDF systems. Despite these advancements, understanding the interplay between processing methods, polymorphic phase evolution, and resulting triboelectric performance remains limited. This review addresses this gap by providing a critical analysis of electrospun PVDF-based TENGs, with a particular focus on β -phase engineering through nanofiller incorporation. Furthermore, recent developments in applications such as wearable electronics, biomedical monitoring, and self-powered sensors are summarized. Finally, key challenges and future research directions are outlined to guide the design of high-performance and scalable PVDF-based triboelectric energy harvesting systems.