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

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 (>107 m−1) are generated and tuned in ferroelectric Pb(Zr0.2Ti0.8)O3 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.

[1]  M. Guo,et al.  Flexoelectric Thin-Film Photodetectors. , 2021, Nano letters.

[2]  Zhong Lin Wang,et al.  Flexophotovoltaic Effect in Potassium Sodium Niobate/Poly(Vinylidene Fluoride‐Trifluoroethylene) Nanocomposite , 2021, Advanced science.

[3]  Guofu Zhou,et al.  Highly Controllable and Silicon-Compatible Ferroelectric Photovoltaic Synapses for Neuromorphic Computing , 2020, iScience.

[4]  L. You,et al.  Continuously controllable photoconductance in freestanding BiFeO3 by the macroscopic flexoelectric effect , 2020, Nature Communications.

[5]  Zhong Lin Wang,et al.  Boosting the Solar Cell Efficiency by Flexo-photovoltaic Effect? , 2019, ACS nano.

[6]  Di Wu,et al.  Ferroelectric Tunnel Junctions: Modulations on the Potential Barrier , 2019, Advanced materials.

[7]  G. Yuan,et al.  Photovoltaic, photo-impedance, and photo-capacitance effects of the flexible (111) BiFeO3 film , 2019, Applied Physics Letters.

[8]  Junling Wang,et al.  Transparent, flexible, fatigue-free, optical-read and non-volatile ferroelectric memories. , 2019, ACS applied materials & interfaces.

[9]  M. Alexe,et al.  Strain-gradient mediated local conduction in strained bismuth ferrite films , 2019, Nature Communications.

[10]  Guofu Zhou,et al.  Thinning ferroelectric films for high-efficiency photovoltaics based on the Schottky barrier effect , 2019, NPG Asia Materials.

[11]  E. Tsymbal,et al.  Enhanced flexoelectricity at reduced dimensions revealed by mechanically tunable quantum tunnelling , 2019, Nature Communications.

[12]  Yun Liu,et al.  Anomalous Photovoltaic Effect in Centrosymmetric Ferroelastic BiVO4 , 2018, Advanced materials.

[13]  M. Alexe,et al.  Flexo-photovoltaic effect , 2018, Science.

[14]  F. Rosei,et al.  Highly Sensitive Switchable Heterojunction Photodiode Based on Epitaxial Bi2FeCrO6 Multiferroic Thin Films. , 2018, ACS applied materials & interfaces.

[15]  Jia-shu Yao,et al.  Touching is believing: interrogating halide perovskite solar cells at the nanoscale via scanning probe microscopy , 2017, npj Quantum Materials.

[16]  K. Jin,et al.  Self-driven visible-blind photodetector based on ferroelectric perovskite oxides , 2017 .

[17]  D. Paparo,et al.  Switchable electric polarization and ferroelectric domains in a metal-organic-framework , 2016, npj Quantum Materials.

[18]  Alessia Polemi,et al.  Erratum: Power conversion efficiency exceeding the Shockley–Queisser limit in a ferroelectric insulator , 2016, Nature Photonics.

[19]  Seung Jin Kim,et al.  Enhancement of the anisotropic photocurrent in ferroelectric oxides by strain gradients. , 2015, Nature nanotechnology.

[20]  E. Guo,et al.  High-sensitive switchable photodetector based on BiFeO3 film with in-plane polarization , 2015 .

[21]  L. You,et al.  Photovoltaic property of domain engineered epitaxial BiFeO3 films , 2014 .

[22]  Wei Huang,et al.  Bandgap tuning of multiferroic oxide solar cells , 2014, Nature Photonics.

[23]  S. Bu,et al.  Flexoelectric Control of Defect Formation in Ferroelectric Epitaxial Thin Films , 2014, Advanced materials.

[24]  R. Sinclair,et al.  Erratum: Codoping titanium dioxide nanowires with tungsten and carbon for enhanced photoelectrochemical performance , 2013, Nature Communications.

[25]  Sang Mo Yang,et al.  Flexoelectric Effect in the Reversal of Self‐Polarization and Associated Changes in the Electronic Functional Properties of BiFeO3 Thin Films , 2013, Advanced materials.

[26]  Pavlo Zubko,et al.  Flexoelectric Effect in Solids , 2013 .

[27]  Kui Yao,et al.  Bulk Photovoltaic Effect at Visible Wavelength in Epitaxial Ferroelectric BiFeO3 Thin Films , 2010, Advanced materials.

[28]  P Shafer,et al.  Above-bandgap voltages from ferroelectric photovoltaic devices. , 2010, Nature nanotechnology.

[29]  S.-W. Cheong,et al.  Switchable Ferroelectric Diode and Photovoltaic Effect in BiFeO3 , 2009, Science.

[30]  C. Mitterer,et al.  Epitaxial growth of Al-Cr-N thin films on MgO(111) , 2008 .

[31]  Gustau Catalan,et al.  The effect of flexoelectricity on the dielectric properties of inhomogeneously strained ferroelectric thin films , 2004 .

[32]  Alastair M. Glass,et al.  High‐voltage bulk photovoltaic effect and the photorefractive process in LiNbO3 , 1974 .