  Piezoelectric fluoropolymers convert mechanical energy to electricity and are
ideal for sustainably providing power to electronic devices. To convert
mechanical energy, a net polarization must be induced in the fluoropolymer,
which is currently achieved via an energy intensive electrical poling process.
Eliminating this process will enable the low-energy production of efficient
energy harvesters. Here, by combining molecular dynamics simulations,
piezoresponse force microscopy, and electrodynamic measurements, we reveal a
hitherto unseen polarization locking phenomena of poly(vinylidene
fluoride-$\mathit{co}$-trifluoroethylene) (PVDF-TrFE) perpendicular to the
basal plane of two-dimensional (2D) Ti$_{3}$C$_{2}$T$_{\mathit{x}}$ MXene
nanosheets. This polarization locking, driven by strong electrostatic
interactions enabled exceptional energy harvesting performance, with a measured
piezoelectric charge coefficient, $\mathit{d_{33}}$, of -52.0 picocoulombs per
newton, significantly higher than electrically poled PVDF-TrFE (approximately
-38 picocoulombs per newton). This study provides a new fundamental and low
energy input mechanism of poling fluoropolymers, which enables new levels of
performance in electromechanical technologies.
