The photovoltage produced by a semiconductor device can be optimized by controlling the interfacial energetics, including the surface dipole and electric field. When a positive surface dipole is introduced to a p-type semiconductor surface, the band edges shift to increase the resulting barrier height in contact with a metal, which in turn improves the photovoltage of the device. To generate a positive surface dipole, highly electronegative moieties must be attached to create a layer of negatively charged species close to the surface. While numerous methods have been developed to modify semiconductor surfaces for control over surface dipole and electric field at the interface, introducing highly electronegative moieties like fluorine atoms directly to the surface is very difficult due to the lack of appropriate synthetic methods. Most fluorinating agents that could introduce fluorine atoms directly to a silicon surface instead etch the silicon (i.e. hydrofluoric acid, xenon difluoride, fluorine plasmas). Indirect modifications are also difficult as fluorocarbon-based nucleophiles are transient and decompose quickly in solution. This work demonstrates that a positive C-F dipole can be introduced to tune the band edges of p-type silicon (p-Si) by placing a monolayer of fluorinated graphene (F–Gr) at the interface of a semiconductor and metal. The barrier heights of bare, hydride-terminated p-Si electrodes coated a layer of platinum (Pt, ~100 nm) were measured using solid-state current-voltage measurements and impedance spectroscopy. These electrodes demonstrated ohmic behavior as expected given the work function of Pt. In comparison, identical electrodes with an interstitial layer of F–Gr demonstrated rectifying behavior and improved barrier heights, controlled by the degree of fluorination of the Gr basal plane. X-ray photoelectron spectroscopy indicated that the formation of Pt silicide at the interface was attenuated by the presence of the monolayer of F–Gr even after stress testing at high temperature. Additionally, these electrodes were tested for hydrogen evolution activity to demonstrate their viability for use in a solar fuels device. F–Gr shows promise to maximize the efficiency of a solar fuels device by favorably tuning the band edges of semiconductor surfaces.