A Robust Densification Strategy Toward Ultrahigh Energy Density in All‐Organic Dielectric Polymer Films

Dielectric capacitors are pivotal components in advanced electronic systems, yet their practical applications are hindered by the low volumetric energy density of commercial dielectric materials. Herein, a facile and scalable densification strategy is proposed to fabricate high‐performance all‐organic composite films by incorporating sucrose, a cost‐effective and hydroxyl‐rich disaccharide, into a poly(vinylidene fluoride‐co‐hexafluoropropylene) [P(VDF‐HFP)] matrix. Benefitting from its abundant hydrogen‐bonding sites, sucrose forms robust hydrogen‐bonded crosslinking networks with P(VDF‐HFP) chains. Those networks untangle and rearrange molecular chains, prompting the transformation from the non‐polar α phase to the polar β / γ phases, while simultaneously elevating crystallinity and constricting amorphous chain spacing to diminish free volume for film densification. By integrating density functional theory calculations, molecular dynamics simulations, and comprehensive experimental characterizations, this study elucidates a novel “Hydrogen‐bond Crosslinking‐Densification” synergistic regulation mechanism at the molecular and mesoscopic scales. Consequently, the optimized P(VDF‐HFP) composite film with 0.8 wt% sucrose achieves a significant breakdown strength of 627.84 MV m ⁻¹ and an ultrahigh discharged energy density of 31.86 J cm ⁻³ , exhibiting a competitive discharged energy density among all‐organic counterparts. This work bridges the gap between molecular‐scale interactions and macroscopic dielectric performance via free volume theory, offering a scalable and cost‐effective pathway for designing high‐performance dielectric materials.