Bulk crystal growth, spectral, optical, thermal, electrical and third-order NLO properties of benzylidene malononitrile derivative single crystal: a promising material for nonlinear optical device applications

Abstract

Bulk organic intramolecular charge transfer nonlinear optical single crystal of 2-(2,4-dimethoxybenzylidene) malononitrile (DMM) with the sizes of 24 × 18 × 13 mm3 have been successfully grown by slow evaporation solution growth technique at 35 °C using acetone as the solvent. The lattice parameters of the grown DMM crystal was evaluated by single crystal X-ray diffraction analysis. The optical transmittance (T) data was taken from the well-polished crystal of DMM, and cut-off wavelength (λ = 483 nm) was identified by UV–Vis spectral studies. Thermal stability and melting point (145.78 °C) were studied with TGA–DSC analysis. The low value of the dielectric constant (er) of DMM suggests that the crystal can be used in the microelectronics industry. The laser-induced damage threshold experiment shows that the grown DMM bulk crystal possess an excellent resistance to laser radiation with a high threshold up to 1.75 GW/cm2, much larger than those of several known organic and inorganic NLO materials. The DMM crystal exhibits positive optical non-linearity and reverse saturation absorption. It also exhibited a nonlinear refractive index (n2) in the order of 10−11 m2/W, a nonlinear absorption coefficient (β) in the order of 10−5 m/W, third order non-linear susceptibility (χ(3)) in the order of 10−5 esu and a second-order molecular hyperpolarizability (γ) in the order of 10−33 esu. All the above results indicate that DMM has a potential application as a useful NLO candidate.