Absorption characteristics of reduced graphene oxide: Application to TCO and solar cells active region

The controlled and patterned reduction of graphene oxide offers a promising method to tune the electronic and optical properties of the material through a wide range. Using ab initio calculations in which the exact exchange energy from Hartree-Fock theory is combined with the exchange-correlation energy obtained from density functional theory (DFT), we studied the electronic, optical, and radiative recombination properties of reduced graphene oxide (rGO). Our model of rGO is based on epoxy functionalised graphene, within which small regions of pristine graphene are formed by reduction. We predict that the gap can be tuned from ~6.85 eV to ~0.25 eV in this manner and that the polarization selective absorption properties can be controlled by manipulating the symmetry of these graphene quantum dots. The optically active can therefore be tuned to ranges suitable for use either as the active medium or a transparent conducting oxide (TCO) in photovoltaic solar cells (PVSCs).