Ultrahigh Energy Density in All‐Organic Composites Synergistically Tailored by PMMA and Molecular Semiconductor

Abstract The inherent limitations (particularly low discharged energy density, U d ≈2 J∙cm −3 ) of commercially available biaxially‐oriented polypropylene (BOPP) film capacitors significantly restrict their broader application in advanced energy storage systems. This study presents a novel approach to overcome this limitation through the development of all‐organic dielectric composite films. A ternary polymer blend matrix, comprising poly(methyl methacrylate) (PMMA), poly(vinylidene fluoride) (PVDF), and poly(vinylidene fluoride‐hexafluoropropylene) (P(VDF‐HFP)), is employed, with the incorporation of 1,4,5,8‐naphthalenetetracarboxylic dianhydride (NTCDA) molecular semiconductors as nanofillers. Systematic investigation reveals that controlled modulation of the PMMA content within the blend matrix effectively suppresss leakage current by reducing crystallinity, minimizing crystallite size, and stabilizing the γ ‐phase in the ferroelectric polymer matrix. Simultaneously, the introduction of NTCDA nanofillers create a high density of deep electron traps, thereby impeding charge injection and enhancing charge carrier trapping within the composite film. The optimized composite film, incorporating 0.5 vol.% NTCDA and 40 wt.% PMMA within the PVDF/P(VDF‐HFP) matrix, demonstrates a substantial enhancement in both breakdown strength ( E b ) of 1054 MV∙m −1 and U d of 28.10 J∙cm −3 , representing a considerable improvement over conventional BOPP‐based capacitor. These findings offer a promising strategy for the design and fabrication of high‐performance all‐organic dielectric composite films for next‐generation energy storage applications.