Wafer scale FeCl3 intercalated graphene electrodes for photovoltaic applications

Abstract

The alteration of graphene’s electrical properties through chemical functionalization is a necessary process in order for graphene to fulfill its potential as a transparent conducting electrode. In this work, we present a method for the transfer and intercalation of large area (wafer scale) graphene samples to produce highly doped FeCl3 intercalated Few Layer Graphene (FeCl3-FLG). Given its excellent flexibility, transmission, and a sheet resistance, comparable to that of Indium Tin Oxide, FeCl3-FLG has potential to replace alternative flexible transparent electrodes as well as compete with rigid transparent electrodes. We assess the effect of functionalization temperature on the degree of intercalation in the large area samples and comparing results to that of 1 cm2 FeCl3-FLG samples. Raman spectroscopy is then used to characterize samples, where we introduce a new figure of merit (〈PosG〉) by which to assess the degree of intercalation in a sample. This is an average G peak position, weighted by the areas of the constituent peaks, which can then be used to map the charge carrier concentration of the sample. The inhomogeneity of the graphene grown by chemical vapor deposition is found to be one of the limiting factors in producing large area, high quality FeCl3-FLG.