A computational study based on first-principles calculations by supercomputers for nanoelectronic devices sometimes leads to results that can rarely be obtained in experimental laboratories with measuring tolerances. In this paper, therefore, we obtained the electronic, electrical, and optoelectrical properties of silicon p-n junction nanostructures by solving Non-Equilibrium Green’s Function (NEGF) using the first-order perturbation theory. We extracted the density of states (DOS), quantum carrier transport coefficient, IV-curve, and optoelectrical behavior by calculating the photocurrent and then plotted the light absorption spectrum. In the studied silicon nanostructure, light absorption is negligible for incident photon energy below 1 eV, and peak absorption occurs at 4 eV. In this research, the developed computational model paves the way for the study of nano-opto-electronic devices. پرونده مقاله