Significant Modulation of Ferroelectric Photovoltaic Behavior by a Giant Macroscopic Flexoelectric Effect Induced by Strain‐Relaxed Epitaxy

Abstract Flexoelectricity has become an emerging tool to tailor the material properties. The flexoelectric modulation of ferroelectric photovoltaic (FEPV) properties is of particular interest, because it offers an opportunity to boost the photovoltaic efficiency. In most previous studies, the flexoelectric effect is generated by local pressing or macroscopic bending, which, however, results in a local or weak modulation of the FEPV behavior. Here, a significant modulation of the FEPV effect by the strain‐relaxed epitaxy (SRE)‐induced giant macroscopic flexoelectric effect is demonstrated. Using SRE, giant strain gradients (>10 7 m −1 ) are generated and tuned in ferroelectric Pb(Zr 0.2 Ti 0.8 )O 3 epitaxial films. Tuning the giant strain gradient can significantly modify the switchable FEPV properties. Particularly, a photovoltage enhancement as large as ≈0.5 V is achieved. It is suggested that the flexoelectric modulation of FEPV behavior may originate from the flexoelectric polarization‐induced depolarization field. This study highlights the immense application potential of the SRE‐induced flexoelectricity in the engineering of functional thin‐film devices.