Growth, structural, third order nonlinear optical properties, dielectric properties, conductivity mechanisms and spectroscopic characterization of a luminescent material trans-diaqua-bis(pyridine-2-carboxylato)-cobalt(ii) dihydrate for optoelectronic applications

Abstract

Single crystals of trans-diaqua-bis(pyridine-2-carboxylato)-cobalt(ii) dihydrate (PCOH) have been successfully grown by slow evaporation technique. The formation of crystalline structure and cell parameters were confirmed by single crystal and powder X-ray diffraction techniques respectively. The structural and optical characterization of the PCOH were analyzed experimentally by FT-IR, FT-Raman and UV–visible spectroscopic technique and theoretical studies by density functional theory method. The charge transfer interactions leading to nonlinear properties taking place in the molecule can be studied by HOMO-LUMO analysis and natural bond orbital analysis. DFT computations using CAM-B3LYP/GenECP and B3LYP/GenECP were performed to determine the linear as well as NLO properties. Open aperture Z-Scan results confirm the competence of these materials as optical limiters (NLO). Furthermore, the PCOH exhibits a blue luminescence emission, as can be seen from the (CIE) chromaticity diagram, and hence the complex may be a promising blue organic light-emitting diode (OLED) in the development of electroluminescent materials for flat-panel-display applications. The electrical properties such as dielectric constant, dielectric loss and ac conductivity of the sample were carried out at different temperatures. The Cole-Cole plot shows the presence of grain and grain boundary, it is found that single relaxation is observed in the crystal. These attractive luminescence emission and third-order nonlinear results indicated that PCOH appear to be promising candidates for optoelectronic applications.