Preparation of chromatic composite hollow nanoparticles containing mixed metal oxides for full-color electrophoretic displays

Abstract

For the first time, the rather challenging full-color electrophoretic display was successfully achieved by colored hollow nanoparticles containing mixed transition metal oxides synthesized via improved emulsifier-free emulsion polymerization and the Pechini sol–gel process. The obtained nanoparticles bear a unique hollow structure with a uniform size of 250 nm and rare fragmentation, as well as bright color. They can migrate rapidly in the electrophoretic fluid, as indicated by the measured zeta potential from −58 to −80 mV and electrophoretic mobility from −3.966 × 10⁻⁶ to −5.121 × 10⁻⁶ cm² V⁻¹ s⁻¹. Electrophoretic ink prototype devices were successfully assembled by mixing these hollow nanoparticles (as colorants) and TiO₂ white particles (as contrast) in a dielectric solvent. Significantly, under an applied bias voltage of 30 V, the devices exhibited excellent performance of high contrast ratio and quick response and thus may find practical application in vivid tricolor electrophoretic displays.