Photovoltaic and impedance spectroscopic characteristics of heterojunction of graphene-PEDOT:PSS composite and n-silicon prepared via solution-based process

Recent investigations involving nanoscale energy conversion using two-dimensional nanomaterials such as graphene and transition metal dichalcogenides (TMDs) hold promise to mitigate future energy challenges. The heterojunction devices designed by interfacing 2D layers with 3D bulk semiconductors (2D/3D heterojunctions) including graphene/silicon and TMDs/silicon are widely explored for the photovoltaic characteristics. Developing a thorough understanding of the interfacial chemistry via impedance spectroscopic analysis will leverage the potential of these 2D/3D junctions for large-scale integrations. Here, the non-vacuum solution-processed reduced graphene oxide (rGO), poly(3,4-ethylenedioxythiophene):polystyrene sulphonate (PEDOT:PSS) and their composite (PEDOT:PSS(rGO)) were spin coated on the silicon (n-Si) substrates for fabrication of heterojunctions, with the device construct of rGO/n-Si, PEDOT:PSS/n-Si and PEDOT:PSS(rGO)/n-Si having Ohmic metal contacts in both top and bottom. The significant effic...