LAUSR

Abstract This study represents a detailed investigation of the influence of post-deposition annealing on structural, morphological and optical properties of 1, 4, 5, 8-naphthalene tetracarboxylic dianhydride, NTCDA, thin films. NTCDA thin films were prepared at room temperature by the thermal evaporation technique. The prepared films were annealed at 373 K and 473 K for 2 h in a vacuum. The results of TGA proved that NTCDA is thermally stable up to 519 K. The X-ray diffraction technique (XRD) was used to investigate the crystal structure of NTCDA powder and thin films. Polycrystalline films were obtained with a preferred orientation in the [100] direction along (h00) zone axis. The negation of the decomposition of NTCDA molecular structure during preparation and/or annealing required employing Fourier transformation infrared (FTIR) technique. The topological properties characterization of as-deposited and annealed NTCDA thin films surfaces concluded that the annealing process induced an enhancement in the film smoothness. The annealing process resulted in significant variations in the optical constants of the NTCDA films. The indirect energy gap values decreased from 3.52 eV to 3.48 eV as a result of annealing up to 473 K. The nonlinear optical effects represented by the nonlinear refractive index, n2 and third-order nonlinear optical susceptibility χ (3) were determined. The nonlinear properties of NTCDA showed a magnificent switching behavior, which suggested the ability to use NTCDA in optical switching devices.