Tuning the Structural, Thermal, and Optical Properties of 7BA+7OBA Liquid Crystal with Dysprosium-Doped Lithium Zinc Phosphate Phosphor Nanoparticles for Advanced Optoelectronic Applications

Abstract

This research investigates the synergistic effects of incorporating dysprosium-doped lithium zinc phosphate (Li₄Zn(PO₄)₂:Dy³⁺) nanoparticles into a binary liquid crystal system composed of p-n-heptylbenzoic acid (7BA) and p-n-heptyl oxybenzoic acid (7OBA). By dispersing the phosphor nanoparticles at varying concentrations (1.5 wt%, 2.5 wt%, and 3.5 wt%), the study explores the resulting changes in the structural, thermal, and optical characteristics of the liquid crystal matrix. The Li₄Zn(PO₄)₂:Dy³⁺ nanoparticles were synthesized via a combustion technique and verified through X-ray diffraction (XRD), confirming their successful integration into the LC mixture. Scanning electron microscopy (SEM) alongside energy-dispersive X-ray spectroscopy (EDS) revealed a uniform nanoparticle dispersion, ensuring consistent interaction with the host material. Optical studies using UV-VIS spectroscopy indicated a progressive reduction in the optical bandgap from 4.04 eV to 3.99 eV as nanoparticle concentration increased, highlighting the tunable optoelectronic potential of the system. Differential scanning calorimetry (DSC) and polarized optical microscopy (POM) were employed to track phase transitions and texture evolutions, offering insight into mesophase behavior modifications. Furthermore, FTIR analysis identified subtle spectral shifts in C=O, C=C, and C-H stretching regions, reflective of molecular interactions between the liquid crystals and nanoparticles. Overall, the integration of Li₄Zn(PO₄)₂:Dy³⁺ phosphor nanoparticles into the 7BA+7OBA matrix offers a promising approach to tailoring liquid crystal performance, paving the way for next-generation display systems and optoelectronic innovations.