Counteranion-directed polar packing in organic cage piezoelectrics
Year: 2026
Type: preprint
Abstract: Organic piezoelectrics are fundamentally limited by the tendency of molecular crystals toward centrosymmetric packing, which forbids a macroscopic piezoelectric response. Here we establish organic cage salts as a programmable platform for overcoming this limitation, in which counteranions direct local cage–anion electrostatic asymmetry, while crystal packing determines whether the resulting polar-shell dipoles cancel or are retained in the solid state. Multiscale dipole analysis reveals that high piezoelectric performance requires both large local cage-anion shell dipoles, arising from anisotropic cage-anion interactions, and their cooperative alignment within the crystal lattice. Across the RCC cage-salt series, RCC3-CF3SO3 gives the largest uncompensated cell dipole and the strongest measured response because its local dipoles are constructively aligned along the polar axis. Flexible RCC3-CF3SO3/PDMS composites (d33,eff = 54.1 pC N-1) generate open-circuit voltages up to 13.5 V, operate stably over 30,000 cycles, and enable self-powered wearable sensing and underwater ultrasonic detection with voltage sensitivities exceeding commercial polymer transducers while preserving frequency fidelity. Because the anion is introduced simply through the choice of acid, this counteranion-directed polar-packing strategy is synthetically modular and potentially transferable to other charged molecular scaffolds.
Source: ChemRxiv
Language: English
Subfield: Biomedical Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7204236300