Ionic Gating of Ultrathin and Leaky Ferroelectrics

Ionic liquids are used to induce reversible large area polarization switching in ultrathin and highly defective ferroelectric films. Long range electrostatic charge control is induced by modifying the electric double layer at an ionic liquid–PbZr_0.2Ti_0.8O₃ interface with electrostatic and electrochemical control of polarization orientation in the ferroelectric layer. The localized nature of the ionic gating mechanism prohibits the presence of leakage current, which has historically limited the switching of ultrathin and/or electrically leaky ferroelectric films in solid metal‐gated capacitor devices. This is demonstrated on ultrathin films and in massively defective films with >30% coverage of direct conducting channels running from surface to ground. This approach opens new design possibilities for integrating ultrathin ferroelectric films in functional electronic devices.