Growth of High-Quality DSTMS Single Crystals with Enhanced Optical Properties for Photonic Applications

Highly efficient organic nonlinear optical stilbazolium crystals of 4-N,N-dimethylamino-4′-N′-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate (DSTMS) single crystal were grown by slow solvent evaporation technique using methanol as a solvent. The structure and cell parameters of the grown crystals were derived from single crystal and powder x-ray diffraction analyses, and the optical properties of the grown crystal were analyzed by a UV–Vis spectrophotometer. The band gap of the grown crystal was found to be 2.28 eV. The vibrating modes of functional groups in the grown crystal were identified by FTIR spectroscopy. The dielectric measurement was made as a function of frequency (1 Hz–1 MHz) at different temperatures (50–200°C) in steps of 50°C. The dielectric constant and dielectric loss were found to be strongly dependent on temperature and frequency of the applied electric field. The semicircle in the Cole–Cole plot showed the presence of dielectric relaxation in the crystal with its radius representing the resistance of the crystal. The resistivity and AC conductivity were calculated from the measured dielectric data.