Comparative Study of the Electrorheological Properties of Various Halide Perovskites.

Although perovskite-structured materials have primarily been widely employed in solar cell applications, limited studies have been conducted in the field of electrorheology (ER). In this study, various halide perovskite materials, including FAPbBr, FAPbI, MAPbBr, MAPbI, CsPbBr, and CsPbI were synthesized for the first time to evaluate their applicability in ER for the first time. Initially, the morphological and chemical properties of these materials were characterized to confirm the successful formation of the perovskite structures. In addition, the as-synthesized halide perovskite materials were dispersed in silicone oil (3.0 wt %) to evaluate their suitability as dispersants in ER fluids. Among these, the CsPbI-based ER fluid exhibited the optimal dielectric properties and the greatest dispersion stability of the various systems examined. In ER applications, the CsPbI-based ER fluid demonstrated the highest ER performance, achieving a shear stress of 99.4 Pa, owing to the synergistic effects of its intrinsic rod-like structure and dielectric properties, which promoted polarization. The aspect ratios of the CsPbI rods were further controlled by modifying the synthetic process, resulting in the generation of both shorter and longer rods. Notably, ER fluids based on CsPbI synthesized via a hydrothermal method yielded rod-like structures with a high aspect ratio of 20, leading to an enhanced ER activity of 128.0 Pa. These results highlight the potential of halide perovskite materials for use in ER applications.