Fig. 1. Self-poling and outstanding macroscopic piezoelectric performance in spin-coated Pb(Zr,Ti)O₃ (PZT) films.

a The concept of self-poling, which leverages macroscopic direct piezoelectricity (d_33,d) achieved in spin-coated ferroelectric films, has the potential to revolutionize commercial materials for micro-electro-mechanical systems (MEMS) applications. b The two-step approach for inducing self-poling in ferroelectric films during fabrication involves texture construction and hierarchical heterogeneity engineering. c Simulated driving fields for self-poling (i.e., polarization alignment) induced by strain gradients, a typical form of hierarchical heterogeneity, compared to random fields and polarizations in films with strain homogeneity. The simulated component has a thickness of 100 nm, equivalent to a single spin-coated layer. d d_33,d in self-poled PZT films deposited on the 4-inch silicon wafer, employing forty repeated spin coatings. The error bars represent different measurements, and the inset is a photograph showing the as-fabricated large-area 4 μm-thick PZT films.