Ion beam irradiation of few-layer graphene and its application to liquid crystal cells

Few-layer graphene was irradiated with a low-energy Ar⁺ ion beam and applied to liquid crystal (LC) cells as both a transparent electrode and a homogeneous alignment enhancer. The optimum conditions for ion-beam-irradiated few-layer graphene (I-G) are 80 eV of beam energy and 1 s of irradiation time, which is confirmed by the decrease of the sheet resistance and increase of water contact angle with similar transmittance to pristine few-layer graphene. It is shown that the ion beam treatment of few-layer graphene under optimized conditions removes the surface contaminants and flattens the surface without damages. LC cells on I-G show similar device performance to that of LC cells based on indium tin oxide (ITO) with rubbing-treated polyimide. These results are very encouraging for replacing ITO electrodes with few-layer graphene in LC display applications.