Tuning of excitons in phosphorene atomic chains

Abstract

Abstract An universal scaling between the exciton binding energy and quasiparticle (QP) band gap was first discovered in two-dimensional (2D) semiconductors such as graphene derivatives, various transition materials dichalcogenides, and black phosphorus (Choi et al 2015 Phys. Rev. Lett. 115 066403; Jiang et al 2017 Phys. Rev. Lett. 118 266401), and later extended to quasi one-dimensional (1D) systems such as carbon nanotubes and graphene nanoribbons. In this work we study the excitonic states in phosphorene atomic chains by using the exact diagonalization method and show that the linear scaling between the exciton binding energy (Ex ) and QP shift ( Δ qs ) can be easily tuned by the dielectric environment. In the presence of weak screening, Ex is seen to increase with Δ qs and exhibits a similar scaling as those 2D materials. As the screening becomes stronger, however, the dependence is found to be reversed, i.e. Ex now decreases when Δ qs increases. More interestingly, we also reveal that Ex may even become nearly constant, independent on the system dimension and Δ qs when the screening reaches a certain strength. These abnormal scaling relations are attributed to the complex nature of excitons in the strongly correlated 1D system.