Atomistic simulations of grain boundaries in CdTe

An improvement in efficiencies of polycrystalline CdTe can possibly be achieved by understanding the role of grain boundaries. Therefore, we systematically studied the atomic and electronic structures of various high angle grain boundaries including asymmetric tilt and twist grain boundaries using empirical potentials and density functional theory (DFT). The density of states analysis revealed that most grain boundaries lead to the formation of midgap states, which can drastically reduce the photovoltaic efficiency. The planar-averaged electrostatic potential analysis indicated attraction for holes around the grain boundary region.