Enhanced photophysical attributes and fast switching dynamics in xanthene dye-blended nematic liquid crystal systems: A molecular level investigation

Abstract

Incorporating fluorescent dyes into liquid crystal matrices has yielded groundbreaking advancements, preserving the exceptional properties of the mesogenic host materials, provided the dye-LC molecular compatibility is ensured. Thus, this study focuses on developing a novel stable and compatible dye-blended system through optimal dispersion of fluorescent dye in liquid crystal. Focusing on xanthene-family dye in nematic liquid crystal, we understand the molecular-level phenomena and interactions crucial for designing novel applications. Homogenously aligned cells were filled up to a concentration of 0.1 wt % of Rhodamine B dye in E7 LC to minimize the impact of dye-dye interactions, thereby facilitating a more accurate assessment of the dye's interaction with the surrounding medium. A comprehensive experimental framework was employed, including dielectric spectroscopy, thermal analysis, optical characterization and electro-optical measurements. The photophysical attributes of the system exhibit a substantial enhancement, characterized by a significant of 42.90 % increase in emission intensity and a remarkable 53.44 % reduction in fall time for dye-blended LC cells compared to pristine LC cells, enabling faster optical switching. This work provides vital insights into the synergy between dye and LC molecules, essential for optimizing performance in advanced fluorescent probes, efficient random lasers, faster optical switches and other next generation devices.