The surface plasmonic resonance (SPR) peak of the intrinsic graphene nanostructures is located at the infrared wavelength. To modify this feature, an armchair graphene nanoribbon (GNR) unit cell is doped by Au atoms with the carrier concentration of \(1.48\times {10}^{13} 1/{cm}^{2}\) . The Fermi level (Ef) of this Au-doped GNR is calculated 0.45 eV below the Dirac point by solving the Schrödinger equation through the Slater-Koster Tight-Binding method utilizing ATK software. The electrical permittivity of the Au-doped GNR is computed by numerical solution of the Kubo formalism considering Ef = 0.45 eV. A periodic array of the Au-doped GNR with the width of 50 nm, and a 100 nm center-to-center gap is deposited on a SiO2 layer. The optical response of the Au-doped GNR/SiO2 interface shows that its SPR peak is located in the wavelength of 650 nm in the visible range. This feature provides a mean to improve the performance of solar cells. The designed nano-surface is exploited at the top and bottom of the Si-based thin film solar cell resulting in an enhanced light absorption due to “hot electron transfer” and SPP effects. The short circuit current density of the cell without and with the nano surface are obtained 15.99 \(mA/{cm}^{2}\) and 23.2 \(mA/{cm}^{2}\) , respectively. The conversion efficiency of the cell increases from 6.33 to 9.48%.
