Synthesis and characterization of organic nonlinear optical material: urea para-nitrophenol

The organic nonlinear single crystals of urea para-nitrophenol (UPN) have been grown using slow evaporation solution growth technique. The formation of the organic product has been confirmed by CHN analysis. The structure of grown crystal was examined by single-crystal X-ray diffraction technique. The presences of functional groups were identified from FT-IR spectrum. The large transmittance properties of the crystal and its linear band gap energy of 3.18 eV inform that the material is suitable for optoelectronic applications. The TG–DTA curve confirms that the grown crystal was thermally stable up to 120 °C. Dielectric constant and dielectric loss values were also measured as a function of frequency between 5 Hz and 5 MHz and temperature from 40 to 100 °C. The second-harmonic generation efficiency of the UPN crystal is found to be 3.5 times greater than that of KDP crystal. The NLO parameters intensity dependent refractive index (n₂), nonlinear absorption coefficient (β) and third-order susceptibility |χ ³| were calculated using Z-scan techniques. The morphology of its UPN crystal was studied using SEM analysis.