© 2022 Elsevier B.V.This research deals with structural, optical, dielectric, nonlinear optical and electrical properties of P3HT organic oligomer by computational and experimental procedures. Based on X-ray pattern, the P3HT film demonstrates a crystalline growth along (100) orientation. Visible transparency of as-grown layer of 87% is recorded and optical band gap is found to be 1.98 eV. Urbach energy of 365 meV is assessed. Dielectric parameters of P3HT such as refractive index and extinction coefficient are found to be 1.55 and 0.18 respectively. Electrical characterization exhibits a higher rectifying behavior and non-ideal conduct of organic device. Under illumination exposure, the photovoltaic parameters of diode are 0.08 V, 94.4 nA, and efficiency is of 1.035. The computational procedure has been pushed to its limits in order to get our value (Egtheor = 2.10 eV) as close to the experiment value (Eg = 1.98 eV) The DOS diagram is shaped showing Eg value within the 6.05–2.1 eV range. As a function of n, the bandgap declines as the second hyperpolarizability increases.