Light‐Written Nonvolatile Polarization via Defect‐Engineered Charge Trapping

Abstract

ABSTRACT Defect engineering offers a practical route to control interfacial charge states in polymer‐inorganic composites, yet translating this control into optically writable and non‐volatile polarization in soft dielectrics remains difficult. Here, we introduce a Polydimethylsiloxane (PDMS)‐based composite that can be written by light to form an interfacial polarization state. The design relies on FeTiO 3 (FTO) nanoparticles with oxygen‐vacancy associated trap states, whose density is tuned by spark plasma sintering to create a trap‐rich polymer‐oxide interface. Under illumination, photocarriers promote interfacial charge transfer by reducing the effective barrier at the metal‐composite contact, producing a rapid rise in interfacial charge accumulation. After the light is removed, a large fraction of the photoexcited electrons becomes immobilized, leaving a residual polarization that relaxes only slowly. We quantify the write‐relax behavior using a triboelectric nanogenerator configuration as a sensitive probe of interfacial charge transfer, and we directly visualize the photo‐written electrostatic state and its retention by Kelvin probe force microscopy. These results present defect‐mediated charge trapping as a materials‐level mechanism for light‐programmable, long‐retention polarization in soft composites, enabling remotely addressable electrostatic interfaces for soft electronic systems.