Organic–Inorganic Rare‐Earth Double Perovskite Ferroelectric with Large Piezoelectric Response and Ferroelasticity for Flexible Composite Energy Harvesters

Hybrid organic-inorganic perovskite (HOIP) ferroelectric materials have great potential for developing self-powered electronic transducers owing to their impressive piezoelectric performance, structural tunability and low processing temperatures. Nevertheless, their inherent brittle and low elastic moduli limit their application in electromechanical conversion. Integration of HOIP ferroelectrics and soft polymers is a promising solution. In this work, a hybrid organic-inorganic rare-earth double perovskite ferroelectric, [RM3HQ]₂RbPr(NO₃)₆ (RM₃HQ = (R)-N-methyl-3-hydroxylquinuclidinium) is presented, which possesses multiaxial nature, ferroelasticity and satisfactory piezoelectric properties, including piezoelectric charge coefficient (d₃₃) of 102.3 pC N^-1 and piezoelectric voltage coefficient (g₃₃) of 680 × 10^-3 V m N^-1. The piezoelectric generators (PEG) based on composite films of [RM3HQ]₂RbPr(NO₃)₆@polyurethane (PU) can generate an open-circuit voltage (V_oc) of 30 V and short-circuit current (I_sc) of 18 µA, representing one of the state-of-the-art PEGs to date. This work has promoted the exploration of new HOIP ferroelectrics and their development of applications in electromechanical conversion devices.