Experimental Observation of Induced Thermoluminescence Nematic Liquid Crystals for Optoelectronic Applications

A new class of intermolecular hydrogen bonded liquid-crystal complex (HBLC) was designed and synthesized from non-mesogenic benzylmalonic acid (BMA) and mesogenic 4n-pentyloxybenzoic acid (5OBA). Intermolecular hydrogen bonds (H-bond) and vibrational functional groups were characterized by using Fourier transform-infrared spectroscopy (FTIR). Textural characterizations and the corresponding transition temperature along with enthalpy values were observed using polarizing optical microscopy (POM) and differential scanning calorimetry (DSC). The optical absorption and emission bandgap energies were calculated by using ultraviolet-visible (UV-vis) and photoluminescence (PL) spectra. The phase transition temperature, thermal stability factor, and thermal span width were calculated and their impact on the liquid crystal properties are discussed. An interesting feature of the BMA+5OBA HBLC complex was the observation of schlieren textures, and the induced thermoluminescence with parachromic variation in the nematic phase is an alternative tool for the manufacture of opto-electronic devices.