Self-assembled porous ferroelectric thin films with a greatly enhanced piezoelectric response

The coupling of the electric and elastic fields in piezoelectric materials makes them indispensable in electromechanical applications such as transducers, sensors, and energy harvesters. In thin films, the piezoelectric response is obstructed by the mechanical clamping of the substrate, resulting in a deterioration of the piezoelectric coefficients. By utilizing soft-chemistry techniques we developed a simple method based on the self-assembly of organometallic precursors in a polymer matrix for the deposition of nanostructured oxide thin films. The implemented macro-porosity leads to local elastic relaxations and greatly enhances the macroscopic electromechanical response. Exceptionally large measured piezoelectric coefficients-reaching the level of bulk ceramics-are associated with the increased elastic compliance of the nanostructured films and the highly mobile ferroelastic domain walls. (C) 2019 Elsevier Ltd. All rights reserved.