Anisotropic Fast Electrically Switchable Emission from Composites of CsPbBr₃ Perovskite Quantum Cuboids in a Nematic Liquid Crystal

Abstract Fast electrically switchable anisotropic photoluminescence from a nano‐soft composite comprising a nematic liquid crystal (LC) and quantum cuboids of a cesium lead halide perovskite is reported. The magnitude of the anisotropy in emission appears to be dictated by the anisotropy of the LC and the capability of the cuboids to form a linear chain, the latter being evidenced through optical and electron microscopy. Application of an ac electric field of small amplitude and its consequent coupling to the LC director is employed to continuously vary the magnitude of the green emission. By appealing to a two‐frequency protocol, the emission could be alternated between the anisotropic limits 40 times faster than with a standard protocol. These studies assume importance to obtain backlight sources having narrow full‐width‐at‐half‐maximum (FWHM) and polarized emission for achieving high‐quality low‐cost LC displays. While conventionally, the light source and the LC are separate entities, the possibility of combining the two functionalities in a single material is highly desirable from the fabrication point of view.