Highly Efficient 3D‐Printed PVDF‐Based Triboelectric Nanogenerators Featuring Polymorphic Perovskite Nanofillers

Abstract The realization of optimal performance in polyvinylidene fluoride (PVDF)‐based triboelectric nanogenerators (TENGs) is fundamentally linked to the enhancement of the β ‐phase content of PVDF ( β ‐PVDF), which is crucial for improving dielectric properties and surface charge density. Among various strategies, the incorporation of semiconducting perovskite nanofillers has been particularly effective in achieving the desired β ‐PVDF phase for TENG applications. Herein, PVDF dielectric films are embedded with polymorphic formamidinium lead triiodide (FAPbI 3 ) perovskite nanofillers and fabricated using a cost‐effective 3D direct‐ink writing setup. The phase transformation of FAPbI 3 nanofillers within the PVDF matrix, in response to varying annealing temperatures, resulted in the formation of PVDF‐FAPbI 3 ( δ ) and PVDF‐FAPbI 3 ( α ) composite films, each exhibiting distinct morphology and dielectric characteristics. The incorporation of δ ‐FAPbI 3 nanofillers rendered the composite film porous and increased the β ‐PVDF content from ≈45% to ≈83%. By converting the δ ‐FAPbI 3 into the α ‐FAPbI 3 through post‐annealing, the composite film transitioned into a mesoporous structure with enhanced tribo‐positive properties. This modification substantially improved the output performance of the TENG, achieving a peak‐to‐peak voltage ( V p‐p ) of 392 Vand a power density of 2587 µW cm − 2 . This work highlights the significant impact of perovskite polymorphism on the performance of TENG devices.