Structural, Optical, and Photoluminescence Studies of ZnO Dispersed p(-n-Decyloxy) Benzoic Acid Liquid Crystalline Compounds

The main theme of the paper was focussed on  the preparation, structural, optical and photoluminescence studuies of p(-n-decyloxy) benzoic acid (10OBA) liquid crystalline (LC) compounds with 1 wt% dispersed ZnO nanoparticles (NPs). The prepared samples were subsequently characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), optical polarizing microscopy (POM), differential scanning calorimetry (DSC), UV-Visible spectroscopy, and photoluminescence (PL) studies. From the XRD, the diffraction peaks observed at 36.2, 42.5, 61.3, and 73.2^o were well resolved, indicating the presence ZnO NPs and the particle size was found to be 65 nm. SEM studies revealed the uniform dispersion and the presence of ZnO NPs in the samples. The textural images of different phases (nematic, smectic) of liquid crystalline compounds of 10OBA pure and 10OBA with 1 wt% dispersed ZnO NPs were observed through the POM with reduced temperature. From the DSC thermograms, the phase transition temperatures and the correponding enthalpy values were estimated. The bandgap reduces for 10OBA LC compound with the dispersion of 1 wt% ZnO NPS and it is estimated as 3.25 eV compared with 4.25 eV for the undoped 10OBA LC compound. PL studies showed the presence of the peak at 616 nm owing to the presence of point defects within the bandgap-like vacancies and interstitials known as deep-level emission.

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