Flexophotovoltaic Effect in Potassium Sodium Niobate/Poly(Vinylidene Fluoride‐Trifluoroethylene) Nanocomposite

Abstract

Flexoelectricity is an electromechanical coupling effect in which electric polarization is generated by a strain gradient. In this investigation, a potassium sodium niobite/poly(vinylidene fluoride-trifluoroethylene) (KNN/PVDF-TrFE)-based nanocomposite is fabricated, and the flexoelectric effect is used to enhance the photovoltaic current (I pv ) in the nanocomposite. It is found that both a pyroelectric current and photovoltaic current can be generated simultaneously in a light illumination process. However, the photovoltaic current (I pv ) in this process contributes ≈85% of the total current. When assessing the effect of flexoelectricity with a curvature of 1/20, the I pv of the curved KNN/PVDF-TrFE (20%) (K/P-20) composite increased by ≈13.9% compared to that of the flat K/P-20 nanocomposite. Similarly, at a curvature of 1/20, the I pv of the K/P-20 nanocomposite is 71.6% higher than that of the PVDF-TrFE film. However, the photovoltaic effect induced by flexoelectricity is much higher than the increased polarization from flexoelectricity, so this effect is called as the flexophotovoltaic effect. Furthermore, the calculated energy conversion efficiency of the K/P-20 film is 0.017%, which is comparable to the previous research result. This investigation shows great promise for PVDF-based nanocomposites in ferroelectric memory device applications.

Flexoelectricity-Enhanced Photovoltaic Effect in Self-Polarized Flexible PZT Nanowire Array Devices

“…According to the data in Figure c, there was no obvious rectification effect from the heterojunction (Schottky junctions) in the PZT-NW/PDMS-based nanocomposite, which was in accordance with the results of Guo et al. and Wang et al , …”

“…25 Recently, Wang et al in our group discovered flexoelectricity-enhanced photovoltaic (FPV) effect in a potassium sodium niobate (KNN)/PVDF-TrFE nanocomposite and found that the I pv of the composite film was enhanced by 13.9% due to the FPV effect. 26 We demonstrated that nanoparticle doping contributes to a high flexoelectric coefficient and a growing FPV effect in a nanocomposite. However, the basic principle of the high flexoelectric coefficient and flexophotovoltaic effect in the composite is not clear.…”

Polymer‐/Ceramic‐based Dielectric Composites for Energy Storage and Conversion

“…[208][209][210][211] However, these composites are out of the scope of this review, and the progress in these composites has been summarized in the recent reviews. [208][209][210] One has to note that ferroelectric composite materials have shown great potentiality for many other new applications such as ferroelectric memory devices, [212,213] flexo-photovoltages, [213] and advanced nano-/micro-electromechanical systems based on flexoelectric composites. [214,215] In addition, the ferroelectric nanocomposite may be a good platform for exploring nontrivial topology in ferroelectrics.…”

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

“…[19,25] This makes the flexoelectric modulation of FEPV behavior a local effect with limited scalability. Macroscopic flexoelectric effect can be achieved by bending a flexible film, [22,26,27] but the generated strain gradients were typically small (<10 5 m −1 ) and hence the modulation of the FEPV effect by bending was not significant (e.g., the bendinginduced photo voltage change was within ≈0.1 V [22] ). Therefore, alternative approaches are needed to obtain large macroscopic flexoelectric effect and consequent significant and scalable modulation of the FEPV effect.…”