Li interaction-induced phase transition from black to blue phosphorene

Abstract

A comprehensive first-principles calculation has been carried out revealing that at sufficiently high Li concentration and certain well-defined configurations a phase transition from black to blue phosphorene can take place. Blue phosphorene, a newly predicted allotrope of phosphorus, possesses unique crystalline and electronic structure and is a promising candidate, not only for fundamental research but also for electronic and optoelectronic applications. Methods of growing high-quality blue phosphorene layers are highly desirable but challenging. Here, a kinetic pathway to grow blue phosphorene layers from black phosphorene layers via Li intercalation is proposed based on first-principles study. This study pointed out that Li atoms intercalated in black phosphorene could act as a ``catalyst'' in the ``reactive region'' of the lone pair of P atoms, leading to a P-P bond breaking and, subsequently, a local structural transformation from an orthorhombic lattice to an assembly of parallel narrow nanoribbons with rhombohedra-like symmetry. During Li deintercalation, these nanoribbons are self-mended and form blue phosphorene layers. The interlayer distance was found to be 4.60 \AA{} for a double layer with AA stacking and 4.13 \AA{} for a multilayer with ABC stacking, indicating monolayer blue phosphorene can be mechanically exfoliated. This study also points out the possibility of new phases in other systems, where intercalation can lead to an unexpected structural phase transition and even a discovery of novel materials.