Superior Transverse Piezoelectricity in a Halide Perovskite Molecular Ferroelectric Thin Film

Piezoelectric
materials with inherent mechanical–electric
coupling effect are a crucial family of functional materials in high-end
information technology. For practical applications, the transverse
piezoelectric performance (d31 or d32) is mainly considered, because this parameter
is a vitally important index to characterize the performance of piezoelectric
thin films. However, the transverse piezoelectricity of the thin films
as a key figure of merit is seldom mentioned in molecular ferroelectrics.
Herein, we report that a new 1D halide perovskite ferroelectric N,N-dimethylallylammoniumCdCl3 (DMAACdCl3) exhibits an above room-temperature ferroelectric
phase transition with a saturated polarization of 1.9 μC cm–2 and a coercive field of 5.0 kV cm–1. The thin film of DMAACdCl3 is successfully fabricated
using an easy processing spinning method and maintains well ferroelectric
properties verified by piezoresponse force microscopy (PFM). More
significantly, the ferroelectric thin film offers superior transverse
piezoelectricity with an in-plane piezoelectric response of about
41 pC N–1, which is about twice that of well-known
piezoelectric polymer PVDF (21 pC N–1). Transverse
piezoelectricity has been scarcely studied in molecular ferroelectrics,
and its exploitation would play an important role in the design of
next-generation smart piezoelectric devices.