A boronic acid-based neutral two-component ferroelectric for piezoelectric energy harvesting and charge-storage applications

Abstract

Boronic acids, known for their nontoxicity, are environmentally friendly and are promising candidates for developing all-organic ferroelectric materials due to their capacity to form polar co-crystals. Herein, we present the first report of ferroelectricity in an amine-boronic acid co-crystal, AP·FPBA, containing 2-aminopyrimidine (AP) (acceptor) and 4-formylphenyl boronic acid (FPBA) (donor). AP·FPBA crystallizes in the polar orthorhombic Pca2₁ space group and shows a distinctive rectangular polarization vs. electric field (P–E) hysteresis loop with saturation polarization of 0.37 μC cm⁻². Piezoresponse force microscopic studies revealed the presence of the microscopic polar domain structures of AP·FPBA along with the amplitude-bias butterfly and phase-bias hysteresis loops. Furthermore, the piezoelectric energy harvesting experiments show the nanogenerator attributes of AP·FPBA with a resultant open circuit voltage of 6.8 V. The capacitance of AP·FPBA was measured to be 13.05 pF, which led to its utility for charge storage applications.