Abstract
The linear and non-linear optical properties of pentacene films were measured at 300 K in the UV–vis-NIR region depending on the measurements of both transmission and reflection. The results of XRD pattern demonstrated the presence of polycrystalline nature as well as the nanostructure characteristics. The mean crystallite size and the microstrain parameters of pentacene were acquired to be 19.15 nm and 6.05 × 10−5, respectively. The type of the optical transition is directly allowed with optical band gaps of 1.57, 2.58 and 3.60 eV. The optical dispersion parameters were acquired and studied as a function of wavelength. The well-known spectroscopic technique is utilized to describe and evaluate the nonlinear optical susceptibilities due to its correlation with the linear refractive index. The spectral behavior of hyperpolarizability and the second order refractive index of pentacene films was achieved. The results emphasize the viability of creating photodetector devices based-pentacene films. The results utilized the studied material as nonlinear optical media because of its remarkable characteristics.