Molecular spin–photovoltaic device based on a graphene nanoflake

Abstract

We generate a spin-polarized current in a hexagonal zigzag graphene nanoflake (hZGNF) by integrating the photovoltaic and spin-dependent transport effects. We consider three different hZGNF configurations and simulate their spin–photovoltaic properties using two probe models in the presence of ferromagnetic contacts as well as the magnetization of zigzag edges. Our results reveal acceptable spin-dependent quantum efficiency, full optical spin polarization, and good optically induced magnetoresistance up to 900%, which can be modified by adjusting the photon energy, by varying the configuration, and also by introducing monovacancy. Interestingly, switching the magnetization of ferromagnetic contacts can approximately invert the spin characteristic of the photocurrent, and so the sign of optical spin polarization. Our findings may provide an efficient way to enhance radiation-induced magnetoresistance in carbon-based molecular junctions.