Abstract
Ferroelectric polymers for energy storage and conversions suffer from high energy losses. Despite great efforts in polymer composites with organic or inorganic fillers, limited successes are achieved with an often compromised dielectric constant (K). Here, a synthesized organic-inorganic hybrid-perfluorinated polyhedral oligomeric silsesquioxane (F-POSS) is presented for creating an ultralow-loss ferroelectric polymer composite. The incorporation of such perfluorinated organosilicons with unique "cage-arm" structure into the polymer not only modulates chain conformations but also inhibits charge transport through its wide bandgap and strong carrier-trapping capabilities. This results in a significant reduction of dielectric/conduction losses and enhanced electric breakdown strength while maintaining a high K, yielding a discharged energy density (U(e)) of 22.3 J cm(-3) with a high efficiency (η) of 82.3%. The utility of F-POSS is further demonstrated in sandwiched devices (with high-K layers comprising quantum dots) that deliver a high U(e) of over 32 J cm(-3) and a η > 80%, alongside an efficient alternating current-driven electroluminescence (luminance > 670 cd m(-2) at 10 MV m(-1)). This work presents a facile strategy for achieving high-K, low-loss ferroelectric polymers, broadening their applications toward advanced energy storage and optoelectronic technologies.