H- and T-Li2O monolayers: Latest addition to 2D flatlands

Abstract

Recent development in two-dimensional materials is due to their exceptional performances in the field of electronics and optical devices in the nano regime. First principles investigation based on density functional theory is used to predict the existence of Li2O in two-dimensional hexagonal monolayer flatlands. Li2O is found to be in H- and T-phase honeycomb structures in monolayer regime. The structural stability was confirmed by phonon calculation which suggests their potential experimental realization. The mechanical properties of both H- and T-phases of Li2O is calculated, the in-plane stiffness of both phases are 10.56% and 15.77% of graphene whereas the Poisson ratio for both phases are more than 1.5 times that of graphene. The electronic band structure calculation reveals that H phase of Li2O is metallic in nature, while the T phase exhibits direct band gap of 2.87 eV. Further, the optical properties for both H and T phases of Li2O suggests their potential applications in optical devices. Present results enlighten that this new two-dimensional Li2O can be utilized to develop stable and efficient optoelectronic materials.