Continuously controllable photoconductance in freestanding BiFeO3 by the macroscopic flexoelectric effect

Abstract

Flexoelectricity induced by the strain gradient is attracting much attention due to its potential applications in electronic devices. Here, by combining a tunable flexoelectric effect and the ferroelectric photovoltaic effect, we demonstrate the continuous tunability of photoconductance in BiFeO3 films. The BiFeO3 film epitaxially grown on SrTiO3 is transferred to a flexible substrate by dissolving a sacrificing layer. The tunable flexoelectricity is achieved by bending the flexible substrate which induces a nonuniform lattice distortion in BiFeO3 and thus influences the inversion asymmetry of the film. Multilevel conductance is thus realized through the coupling between flexoelectric and ferroelectric photovoltaic effect in freestanding BiFeO3. The strain gradient induced multilevel photoconductance shows very good reproducibility by bending the flexible BiFeO3 device. This control strategy offers an alternative degree of freedom to tailor the physical properties of flexible devices and thus provides a compelling toolbox for flexible materials in a wide range of applications.

2–2 Type PVDF‐Based Composites Interlayered by Epitaxial (111)‐Oriented BTO Films for High Energy Storage Density

“…The enhancement of E b can be explained by the fact that a depolarization electric field at the 2–2 type interfaces between BTO layers and PVDF layers inhibits the mobile charges across interfaces, which is confirmed by phase‐field simulations. In future cases, the preparation process is also applicable to develop a series of 2–2 type composites interlayered by single‐crystal perovskite films, such as SrTiO 3 , [ 64 ] BiFeO 3 , [ 65 ] etc. This kind of composite can further enhance the U further and may be applied in electronics and electrical power systems.…”

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

“…For example, Chu et al [21] observed a significant strain gradient-induced enhancement of photocurrent at the morphotropic phase boundaries (MPBs) in mixed-phase BiFeO 3 (BFO) films. In addition, Guo et al [22] demonstrated the 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.…”

Mixed Triboelectric and Flexoelectric Charge Transfer at the Nanoscale

“…In contrast, flexoelectricity, the coupling between an electric polarization and strain gradient, [ 11 , 12 , 13 , 14 , 15 ] has been demonstrated in recent studies on various material systems to modulate physical properties, for example, a photovoltaic effect, Schottky barrier, resistance, or polarization, has been reported in BiFeO 3 , [ 16 ] halide perovskite, [ 17 ] Si, [ 18 ] TiO 2 , [ 18 , 19 ] and (Nb‐)SrTiO 3 , [ 14 , 15 , 18 , 19 ] to name a few. Basically, flexoelectricity is a universal property of all dielectric materials including centrosymmetric materials, which occurs under an inhomogeneous strain field.…”