▎ 摘　　要

We investigate the low-energy electronic transport across grain boundaries in graphene ribbons and infinite flakes employing two distinct techniques. Using the recursive Green's-function method, we compute the electronic transmittance across different types of grain boundaries in graphene ribbons and flakes. We use the charge and current density spatial distributions to enhance our understanding of their electronic transport properties. We find that electronic transport depends both on the grain boundaries' microscopic details and on their orientation. In addition, we employ the transfer-matrix formalism to analytically study the electronic transport across a class of zigzag grain boundaries with periodicity 3. We find that these grain boundaries give rise to intervalley scattering.