Increased Optical Absorption and Light–Matter Interaction in Silicon Thin-Film Solar Cell Nanostructure Using Graphene and 2-D Au/Ag Nanograting

Abstract

Silicon solar cells with graphene have commonly some drawbacks in assuming Schottky junction configurations, small active areas, carrier’s recombination at interface of graphene/silicon junction, high cost, and complex manufacture processes. We report a new silicon thin-film solar cell structure with graphene, gold (Au) nanograting, and back silver (Ag) contact, which has advantages of simple fabrication method, no graphene/silicon Schottky junction complexity, high absorption, and high short circuit current density. We simulate the proposed specific graphene–silicon solar cell layer assembly by using the 2-D FEM under the standard global AM1.5 spectrum conditions. The generation of strong magnetic resonance field arises due to graphene sheet covered on top of gold nanograting and specific dielectric spacer thickness and slit period and leads to increase absorption and transport of charge carriers in p-i-n silicon layer sandwiched between dielectric spacer and back contact. We report that absorption improvement can be simply tuned by adjusting few geometric parameters of proposed device and maximum absorption is achieved up to 80% in near-infrared wavelength ranges. As an outcome, maximum short circuit current density ( $J_{\mathrm {sc}}$ ) of 32 mA/cm2, open-circuit voltage ( $V_{\mathrm {oc}}$ ) of 0.45 V, and calculated power conversion efficiency of 10.5% are achieved without chemical doping of graphene. The proposed simple structure configuration of silicon thin-film solar cell with graphene on top offers flexible tuneability, high short circuit current values, and increased optical absorption that are beneficial for practical fabrication and industrial applications.